Bacteria

When penicillin became widely available during the second world war, it was a medical miracle, rapidly vanquishing the biggest wartime killer infected wounds. Discovered initially by a French medical student, Ernest Duchesne, in 1896, and then rediscovered by Scottish physician Alexander Fleming in 1928, the product of the soil mold Penicillium crippled many types of disease-causing bacteria. But just four years after drug companies began mass-producing penicillin in 1943, microbes began appearing that could resist it.

The first bug to battle penicillin was Staphylococcus aureus. This bacterium is often a harmless passenger in the human body, but it can cause illness, such as pneumonia or toxic shock syndrome, when it overgrows or produces a toxin. In 1967, another type of penicillin-resistant pneumonia, caused by Streptococcus pneumoniae and called pneumococcus, surfaced in a remote village in Papua New Guinea. At about the same time, American military personnel in southeast Asia were acquiring penicillin-resistant gonorrhea from prostitutes.

By 1976, when the soldiers had come home, they brought the new strain of gonorrhea with them, and physicians had to find new drugs to treat it. In 1983, a hospital-acquired intestinal infection caused by the bacterium Enterococcus faecium joined the list of bugs that outwit penicillin. Antibiotic resistance spreads fast. Between 1979 and 1987, for example, only 0. 02 percent of pneumococcus strains infecting a large number of patients surveyed by the national Centers for Disease Control and Prevention were penicillin-resistant.

CDC’s survey included 13 hospitals in 12 states. Today, 6. 6 percent of pneumococcus strains are resistant, according to a report in the June 15, 1994, Journal of the American Medical Association by Robert F. Breiman, M. D. , and colleagues at CDC. The agency also reports that in 1992, 13,300 hospital patients died of bacterial infections that were resistant to antibiotic treatment. Why has this happened? “There was complacency in the 1980s. The perception was that we had licked the bacterial infection problem. Drug companies weren’t working on new agents.

They were concentrating on other areas, such as viral infections,” says Michael Blum, M. D. , medical officer in the Food and Drug Administration’s division of anti-infective drug products. “In the meantime, resistance increased to a number of commonly used antibiotics, possibly related to overuse of antibiotics. In the 1990s, we’ve come to a point for certain infections that we don’t have agents available. ” According to a report in the April 28, 1994, New England Journal of Medicine, researchers have identified bacteria in patient samples that resist all currently available antibiotic drugs.

Survival of the Fittest The increased prevalence of antibiotic resistance is an outcome of evolution. Any population of organisms, bacteria included, naturally includes variants with unusual traits in this case, the ability to withstand an antibiotic’s attack on a microbe. When a person takes an antibiotic, the drug kills the defenseless bacteria, leaving behind or “selecting,” in biological terms those that can resist it. These renegade bacteria then multiply, increasing their numbers a millionfold in a day, becoming the predominant microorganism.

The antibiotic does not technically cause the resistance, but allows it to happen by creating a situation where an already existing variant can flourish. “Whenever antibiotics are used, there is selective pressure for resistance to occur. It builds upon itself. More and more organisms develop resistance to more and more drugs,” says Joe Cranston, Ph. D. , director of the department of drug policy and standards at the American Medical Association in Chicago. A patient can develop a drug-resistant infection either by contracting a resistant bug to begin with, or by having a resistant microbe emerge in the body once antibiotic treatment begins.

Drug-resistant infections increase risk of death, and are often associated with prolonged hospital stays, and sometimes complications. These might necessitate removing part of a ravaged lung, or replacing a damaged heart valve. Bacterial Weaponry Disease-causing microbes thwart antibiotics by interfering with their mechanism of action. For example, penicillin kills bacteria by attaching to their cell walls, then destroying a key part of the wall. The wall falls apart, and the bacterium dies.

Resistant microbes, however, either alter their cell walls so penicillin can’t bind or produce enzymes that dismantle the antibiotic. In another scenario, erythromycin attacks ribosomes, structures within a cell that enable it to make proteins. Resistant bacteria have slightly altered ribosomes to which the drug cannot bind. The ribosomal route is also how bacteria become resistant to the antibiotics tetracycline, streptomycin and gentamicin. How Antibiotic Resistance Happens Antibiotic resistance results from gene action. Bacteria acquire genes conferring resistance in any of three ways.

In spontaneous DNA mutation, bacterial DNA (genetic material) may mutate (change) spontaneously (indicated by starburst). Drug-resistant tuberculosis arises this way. In a form of microbial sex called transformation, one bacterium may take up DNA from another bacterium. Pencillin-resistant gonorrhea results from transformation. Most frightening, however, is resistance acquired from a small circle of DNA called a plasmid, that can flit from one type of bacterium to another. A single plasmid can provide a slew of different resistances.

In 1968, 12,500 people in Guatemala died in an epidemic of Shigella diarrhea. The microbe harbored a plasmid carrying resistances to four antibiotics! A Vicious Cycle: More Infections and Antibiotic Overuse Though bacterial antibiotic resistance is a natural phenomenon, societal factors also contribute to the problem. These factors include increased infection transmission, coupled with inappropriate antibiotic use. More people are contracting infections. Sinusitis among adults is on the rise, as are ear infections in children. A report by CDC’s Linda F. McCaig and James M. Hughes, M. D. , in the Jan. 18, 1995, Journal of the American Medical Association, tracks antibiotic use in treating common illnesses. The report cites nearly 6 million antibiotic prescriptions for sinusitis in 1985, and nearly 13 million in 1992. Similarly, for middle ear infections, the numbers are 15 million prescriptions in 1985, and 23. 6 million in 1992. Causes for the increase in reported infections are diverse. Some studies correlate the doubling in doctor’s office visits for ear infections for preschoolers between 1975 and 1990 to increased use of day-care facilities.

Homelessness contributes to the spread of infection. Ironically, advances in modern medicine have made more people predisposed to infection. People on chemotherapy and transplant recipients taking drugs to suppress their immune function are at greater risk of infection. “There are the number of immunocompromised patients, who wouldn’t have survived in earlier times,” says Cranston. “Radical procedures produce patients who are in difficult shape in the hospital, and are prone to nosocomial hospital-acquired infections.

Also, the general aging of patients who live longer, get sicker, and die slower contributes to the problem,” he adds. Though some people clearly need to be treated with antibiotics, many experts are concerned about the inappropriate use of these powerful drugs. “Many consumers have an expectation that when they’re ill, antibiotics are the answer. They put pressure on the physician to prescribe them. Most of the time the illness is viral, and antibiotics are not the answer. This large burden of antibiotics is certainly selecting resistant bacteria,” says Blum.

Another much-publicized concern is use of antibiotics in livestock, where the drugs are used in well animals to prevent disease, and the animals are later slaughtered for food. “If an animal gets a bacterial infection, growth is slowed and it doesn’t put on weight as fast,” says Joe Madden, Ph. D. , strategic manager of microbiology at FDA’s Center for Food Safety and Applied Nutrition. In addition, antibiotics are sometimes administered at low levels in feed for long durations to increase the rate of weight gain and improve the efficiency of converting animal feed to units of animal production.

FDA’s Center for Veterinary Medicine limits the amount of antibiotic residue in poultry and other meats, and the U. S. Department of Agriculture monitors meats for drug residues. According to Margaret Miller, Ph. D. , deputy division director at the Center for Veterinary Medicine, the residue limits for antimicrobial animal drugs are set low enough to ensure that the residues themselves do not select resistant bacteria in (human) gut flora. FDA is investigating whether bacteria resistant to quinolone antibiotics can emerge in food animals and cause disease in humans.

Although thorough cooking sharply reduces the likelihood of antibiotic-resistant bacteria surviving in a meat meal to infect a human, it could happen. Pathogens resistant to drugs other than fluoroquinolones have sporadically been reported to survive in a meat meal to infect a human. In 1983, for example, 18 people in four midwestern states developed multi-drug-resistant Salmonella food poisoning after eating beef from cows fed antibiotics. Eleven of the people were hospitalized, and one died. A study conducted by Alain Cometta, M. D. , and his colleagues at the Centre Hospitalier Universitaire Vaudois in Lausanne, Switzerland, and reported in the April 28, 1994, New England Journal of Medicine, showed that increase in antibiotic resistance parallels increase in antibiotic use in humans. They examined a large group of cancer patients given antibiotics called fluoroquinolones to prevent infection. The patients’ white blood cell counts were very low as a result of their cancer treatment, leaving them open to infection. Between 1983 and 1993, the percentage of such patients receiving antibiotics rose from 1. 4 to 45.

During those years, the researchers isolated Escherichia coli bacteria annually from the patients, and tested the microbes for resistance to five types of fluoroquinolones. Between 1983 and 1990, all 92 E. coli strains tested were easily killed by the antibiotics. But from 1991 to 1993, 11 of 40 tested strains (28 percent) were resistant to all five drugs. Towards Solving the Problem Antibiotic resistance is inevitable, say scientists, but there are measures we can take to slow it. Efforts are under way on several fronts improving infection control, developing new antibiotics, and using drugs more appropriately.

Barbara E. Murray, M. D. , of the University of Texas Medical School at Houston writes in the April 28, 1994, New England Journal of Medicine that simple improvements in public health measures can go a long way towards preventing infection. Such approaches include more frequent hand washing by health-care workers, quick identification and isolation of patients with drug-resistant infections, and improving sewage systems and water purity in developing nations. Drug manufacturers are once again becoming interested in developing new antibiotics.

These efforts have been spurred both by the appearance of new bacterial illnesses, such as Lyme disease and Legionnaire’s disease, and resurgences of old foes, such as tuberculosis, due to drug resistance. FDA is doing all it can to speed development and availability of new antibiotic drugs. “We can’t identify new agents that’s the job of the pharmaceutical industry. But once they have identified a promising new drug for resistant infections, what we can do is to meet with the company very early and help design the development plan and clinical trials,” says Blum.

In addition, drugs in development can be used for patients with multi-drug-resistant infections on an “emergency IND (compassionate use)” basis, if the physician requests this of FDA, Blum adds. This is done for people with AIDS or cancer, for example. No one really has a good idea of the extent of antibiotic resistance, because it hasn’t been monitored in a coordinated fashion. “Each hospital monitors its own resistance, but there is no good national system to test for antibiotic resistance,” says Blum. This may soon change.

CDC is encouraging local health officials to track resistance data, and the World Health Organization has initiated a global computer database for physicians to report outbreaks of drug-resistant bacterial infections. Experts agree that antibiotics should be restricted to patients who can truly benefit from them that is, people with bacterial infections. Already this is being done in the hospital setting, where the routine use of antibiotics to prevent infection in certain surgical patients is being reexamined. We have known since way back in the antibiotic era that these drugs have been used inappropriately in surgical prophylaxis preventing infections in surgical patients. But there is more success in limiting antibiotic use in hospital settings, where guidelines are established, than in the more typical outpatient settings,” says Cranston. Murray points out an example of antibiotic prophylaxis in the outpatient setting children with recurrent ear infections given extended antibiotic prescriptions to prevent future infections. Another problem with antibiotic use is that patients often stop taking the drug too soon, because symptoms improve. However, this merely encourages resistant microbes to proliferate. The infection returns a few weeks later, and this time a different drug must be used to treat it. Targeting TB Stephen Weis and colleagues at the University of North Texas Health Science Center in Fort Worth reported in the April 28, 1994, New England Journal of Medicine on research they conducted in Tarrant County, Texas, that vividly illustrates how helping patients to take the full course of their medication can actually lower resistance rates.

The subject tuberculosis. TB is an infection that has experienced spectacular ups and downs. Drugs were developed to treat it, complacency set in that it was beaten, and the disease resurged because patients stopped their medication too soon and infected others. Today, one in seven new TB cases is resistant to the two drugs most commonly used to treat it (isoniazid and rifampin), and 5 percent of these patients die. In the Texas study, 407 patients from 1980 to 1986 were allowed to take their medication on their own.

From 1986 until the end of 1992, 581 patients were closely followed, with nurses observing them take their pills. By the end of the study, the relapse rate which reflects antibiotic resistance- fell from 20. 9 to 5. 5 percent. This trend is especially significant, the researchers note, because it occurred as risk factors for spreading TB including AIDS, intravenous drug use, and homelessness were increasing. The conclusion: Resistance can be slowed if patients take medications correctly.

Narrowing the Spectrum Appropriate prescribing also means that physicians use “narrow spectrum” antibiotics those that target only a few bacterial types whenever possible, so that resistances can be restricted. The only national survey of antibiotic prescribing practices of office physicians, conducted by the National Center for Health Statistics, finds that the number of prescriptions has not risen appreciably from 1980 to 1992, but there has been a shift to using costlier, broader spectrum agents.

This prescribing trend heightens the resistance problem, write McCaig and Hughes, because more diverse bacteria are being exposed to antibiotics. One way FDA can help physicians choose narrower spectrum antibiotics is to ensure that labeling keeps up with evolving bacterial resistances. Blum hopes that the surveillance information on emerging antibiotic resistances from CDC will enable FDA to require that product labels be updated with the most current surveillance information. Many of us have come to take antibiotics for granted.

A child develops strep throat or an ear infection, and soon a bottle of “pink medicine” makes everything better. An adult suffers a sinus headache, and antibiotic pills quickly control it. But infections can and do still kill. Because of a complex combination of factors, serious infections may be on the rise. While awaiting the next “wonder drug,” we must appreciate, and use correctly, the ones that we already have. If this bacterium could be shown four times bigger, it would be the right relative size to the virus beneath it. Both are microscopic and are shown many times larger than life. ) Although bacteria are single-celled organisms, viruses are far simpler, consisting of one type of biochemical (a nucleic acid, such as DNA or RNA) wrapped in another (protein). Most biologists do not consider viruses to be living things, but instead, infectious particles. Antibiotic drugs attack bacteria, not viruses.  When microbes began resisting penicillin, medical researchers fought back with chemical cousins, such as methicillin and oxacillin.

By 1953, the antibiotic armamentarium included chloramphenicol, neomycin, terramycin, tetracycline, and cephalosporins. But today, researchers fear that we may be nearing an end to the seemingly endless flow of antimicrobial drugs. At the center of current concern is the antibiotic vancomycin, which for many infections is literally the drug of “last resort,” says Michael Blum, M. D. , medical officer in FDA’s division of anti-infective drug products. Some hospital-acquired staph infections are resistant to all antibiotics except vancomycin. Now vancomycin resistance has turned up in another common hospital bug, enterococcus.

And since bacteria swap resistance genes like teenagers swap T-shirts, it is only a matter of time, many microbiologists believe, until vancomycin-resistant staph infections appear. “Staph aureus may pick up vancomycin resistance from enterococci, which are found in the normal human gut,” says Madden. And the speed with which vancomycin resistance has spread through enterococci has prompted researchers to use the word “crisis” when discussing the possibility of vancomycin-resistant staph. Vancomycin-resistant enterococci were first reported in England and France in 1987, and appeared in one New York City hospital in 1989.

By 1991, 38 hospitals in the United States reported the bug. By 1993, 14 percent of patients with enterococcus in intensive-care units in some hospitals had vancomycin-resistant strains, a 20-fold increase from 1987. A frightening report came in 1992, when a British researcher observed a transfer of a vancomycin-resistant gene from enterococcus to Staph aureus in the laboratory. Alarmed, the researcher immediately destroyed the bacteria.

We are surrounded by billions of bacteria and viruses. To many of them, a human being is like a walking smorgasbord, offering nearly limitless resources that they can use for energy and reproduction. Luckily for us, getting into the human body is not an easy task! From the point of view of these tiny organisms, a human is a bit like a fortress. The skin is thick and very hard to penetrate. In addition, the skin also produces a variety of substances that are harmful to invaders. Openings such as the eyes, nose, and mouth are protected by fluids or sticky mucus that capture harmful attackers.

The respiratory tract also has mechanical defenses in the form of cilia, tiny hairs that remove particles. Intruders that get as far as the stomach are up against a sea of stomach acid that kills most of them. But in spite of our fantastic defenses, hostile invaders still manage to get through. Some enter along with our food, while others may sneak in via the nose. And, as we all know, many things can break through our skin. In everyday life we often receive cuts or scrapes, and every time this happens we face the risk of a full-scale invasion from bacteria or viruses.

What is the magic, then, that keeps us healthy most of the time? When we receive a cut, and when invaders enter the body, cells are destroyed. The dying cells trigger an automatic response called inflammation, which includes dilated blood vessels and increased blood flow. An inflammation is the body’s equivalent to a burglar alarm. Once it goes off, it draws defensive cells to the damaged area in great numbers. Increased blood flow helps defensive cells reach the place where they’re needed. It also accounts for the redness and swelling that occur.

Immune Cells: The Defense The defensive cells are more commonly known as immune cells. They are part of a highly effective defense force called the immune system. The cells of the immune system work together with different proteins to seek out and destroy anything foreign or dangerous that enters our body. It takes some time for the immune cells to be activated – but once they’re operating at full strength, there are very few hostile organisms that stand a chance. Immune cells are white blood cells produced in huge quantities in the bone marrow.

There are a wide variety of immune cells, each with its own strengths and weaknesses. Some seek out and devour invading organisms, while others destroy infected or mutated body cells. Yet another type has the ability to release special proteins called antibodies that mark intruders for destruction by other cells. But the really cool thing about the immune system is that it has the ability to “remember” enemies that it has fought in the past. If the immune system detects a “registered” invader, it will strike much more quickly and more fiercely against it.

As a result, an invader that tries to attack the body a second time will most likely be wiped out before there are any symptoms of disease. When this happens, we say that the body has become immune. Bacteria and Viruses: Our Main Enemies | A virus needs a host cell to reproduce. | Now that you know a bit about our defenses, let’s take a closer look at our primary enemies. Bacteria and viruses are the organisms most often responsible for attacking our bodies. Most bacteria are free living, while others live in or on other organisms, including humans.

Unfortunately, many bacteria that have human hosts produce toxins (poisons) that damage the body. Not all bacteria are harmful, though. Some are neutral and many are even desirable as they fulfill important functions in the body. Bacteria are complete organisms that reproduce by cell division. Viruses, on the other hand, cannot reproduce on their own. They need a host cell. They hijack body cells of humans or other species, and trick them into producing new viruses that can then invade other cells. Frequently, the host cell is destroyed during the process. Pathogens and Antigens

In daily life we might speak of viruses, bacteria, and toxins. However, when reading about the immune system you’ll often come across the words antigen and pathogen. An antigen is a foreign substance that triggers a reaction from the immune system. Antigens are often found on the surfaces of bacteria and viruses. A pathogen is a microscopic organism that causes sickness. Hostile bacteria and viruses are examples of pathogens The Immune System – in More Detail The immune system is one of nature’s more fascinating inventions. With ease, it protects us against billions of bacteria, viruses, and other parasites.

Most of us never reflect upon the fact that while we hang out with our friends, watch TV, or go to school, inside our bodies, our immune system is constantly on the alert, attacking at the first sign of an invasion by harmful organisms. The immune system is very complex. It’s made up of several types of cells and proteins that have different jobs to do in fighting foreign invaders. In this section, we’ll take a look at the parts of the immune system in some detail. If you’re reading about the immune system for the first time, we recommend that you take a look at the Immune System Overview first (see link below).

The Complement System The first part of the immune system that meets invaders such as bacteria is a group of proteins called the complement system. These proteins flow freely in the blood and can quickly reach the site of an invasion where they can react directly with antigens – molecules that the body recognizes as foreign substances. When activated, the complement proteins can | -| | trigger inflammation| | -| | attract eater cells such as macrophages to the area| | -| | coat intruders so that eater cells are more likely to devour them| | -| | kill intruders|

Phagocytes This is a group of immune cells specialized in finding and “eating” bacteria, viruses, and dead or injured body cells. There are three main types, the granulocyte, the macrophage, and the dendritic cell. | The granulocytes often take the first stand during an infection. They attack any invaders in large numbers, and “eat” until they die. The pus in an infected wound consists chiefly of dead granulocytes. A small part of the granulocyte community is specialized in attacking larger parasites such as worms. | The macrophages (“big eaters”) are slower to respond to invaders than the granulocytes, but they are larger, live longer, and have far greater capacities. Macrophages also play a key part in alerting the rest of the immune system of invaders. Macrophages start out as white blood cells called monocytes. Monocytes that leave the blood stream turn into macrophages. | | The dendritic cells are “eater” cells and devour intruders, like the granulocytes and the macrophages. And like the macrophages, the dendritic cells help with the activation of the rest of the immune system.

They are also capable of filtering body fluids to clear them of foreign organisms and particles. | Lymphocytes – T cells and B cells | | The lymphatic system| The receptors match only one specific antigen. | White blood cells called lymphocytes originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes, spleen, and thymus. There are two main types of lymphatic cells, T cells and B cells. The lymphatic system also involves a transportation system – lymph vessels – for transportation and storage of lymphocyte cells within the body.

The lymphatic system feeds cells into the body and filters out dead cells and invading organisms such as bacteria. On the surface of each lymphatic cell are receptors that enable them to recognize foreign substances. These receptors are very specialized – each can match only one specific antigen. To understand the receptors, think of a hand that can only grab one specific item. Imagine that your hands could only pick up apples. You would be a true apple-picking champion – but you wouldn’t be able to pick up anything else. In your body, each single receptor equals a hand in search of its “apple. The lymphocyte cells travel through your body until they find an antigen of the right size and shape to match their specific receptors. It might seem limiting that the receptors of each lymphocyte cell can only match one specific type of antigen, but the body makes up for this by producing so many different lymphocyte cells that the immune system can recognize nearly all invaders.

T cells T cells come in two different types, helper cells and killer cells. They are named T cells after the thymus, an organ situated under the breastbone. T cells are produced in the bone marrow and later move to the thymus where they mature. Helper T cells are the major driving force and the main regulators of the immune defense. Their primary task is to activate B cells and killer T cells. However, the helper T cells themselves must be activated. This happens when a macrophage or dendritic cell, which has eaten an invader, travels to the nearest lymph node to present information about the captured pathogen. The phagocyte displays an antigen fragment from the invader on its own surface, a process called antigen presentation. When the receptor of a helper T cell recognizes the antigen, the T cell is activated.

Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells. | PARTS AND FUNCTIONS White Blood Cells * The smallest parts of the immune system are the myriad types of white blood cells that are responsible for demolishing malicious bacterial, viral and tumor cells. T cells serve as both managers and infection killers. They are responsible for activating and communicating with other types of white blood cells before destroying malignant cells like parasites and tumors. Natural killer cells directly attack virus cells and tumor cells such as lymphoma, melanoma and herpes.

They work alone without communicating with other parts of the immune system. B cells work to produce antibodies that attach themselves to foreign cells as a sign to natural killer cells and T cells to attack and destroy. Bone Marrow * An essential aspect of the immune system–and the origin of all types of immune system cells–is red bone marrow. Bone marrow is a specific type of tissue that grows in the empty centers of bones. This tissue uses the process of hematopoiesis to manipulate its own stem cells into B cells and natural killer cells, as well as the foundational pieces of other immune ells like T cells. Once they are created, these cells migrate out of the marrow tissue and circulate through the blood stream to infection sites, other glands or around the body as general patrol entities. Thymus Gland

* The foundations of T cells produced in the bone marrow, called thymocytes, leave the tissue and travel to the thymus gland for completion. The thymus is a small gland located near the lungs in the upper torso. Thymocytes complete their maturation in the thymus through the process of thymic education, where each cell is developed and examined for maximum efficiency.

Cells that are not strong enough to provide immune support are destroyed and absorbed by the thymus, while the successfully matured cells are excreted from the gland into the blood stream. Spleen The spleen, which is located on the left side of the abdomen just under the lung, is a blood filter that works to remove malignant cells from the blood stream. To assist in this function, it holds a significant store of B cells, T cells and natural killer cells to help eliminate any contaminants that are caught.

The spleen also assists in immune function by holding a store of red blood cells and platelets that can be deployed as support for the immune cells in the event of an infection or wound. Lymph Nodes * Lymph nodes, found throughout the body, are also integral parts of the immune system that filter tissue fluid for bacteria cells, tumor cells and viral particles. Like the spleen, lymph nodes are full of the various types of white blood cells that clean the lymph fluid before returning it to various areas of the body.

Lymph nodes are located in the head, neck, arms, legs, abdomen and genital area of the human body and are connected through a network of afferent lymphatic vessels. In the event of an infection, white blood cells can use these lymphatic vessels to quickly communicate with other parts of the immune system. SKIN The skin is the largest organ in area. With the Langerhans cells in the lowest epidermal layers, it is equipped with specialized immunologically competent cells. The Langerhans cells play a central role in the skin’s immune system and are an integral part of the body’s total defence system.

The body’s own defence against microorganisms begins directly at the skin surface. Special fatty acids from the sebaceous glands (i) and the secretions of certain bacteria belonging to the physiological skin flora inhibit the growth of fungi and bacteria. Certain enzymes present in sweat (lysozymes) can destroy the cell walls of invading bacteria. If a foreign body passes this first line of defence – for example, due to skin damage – the skin’s immune system responds. Many cells help fend off foreign bodies. Among these are cells – like the Langerhans cells – that are specific to the skin’s immune system.

Natural cod stocks going down.

There has been much press coverage of the decline in natural cod stocks due to over fishing in the North Sea.

I like my cod and chips and so was quite concerned about this. It may be too late to get the numbers back up to 1970’s levels but less documented by the press, is the rapid growth of mariculture, the cultivation of marine organisms for food, which retailers say could ‘revolutionise the fishing industry’ (2).

I visited the Manx Mariculture fish hatchery to investigate the principles behind fish farming and soon discovered that it was not without its problems. As my guide, Rick Fullerton, explained, a bacterial problem in the live feed meant that the hatchery faced a crisis in the year 2006 when only a few hundred cod were produced instead of the target 1 million. This is a common problem in mariculture and there is the potential for exciting new developments in the production of live feed which could eliminate this problem in the future.

Use of live feed as an answer

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In order to kill bacteria, live feed may be disinfected or treated with UV rays (6). A recent study (Cutts, Sherwood and Treasurer) showed that bacterial numbers were lower in tanks of live feed treated with Pyceze, often used as a disinfectant of water and a preservative in cosmetic products, and the survival of larvae was 6.1% higher (6). Other future developments in the production of live feed may include using rotifers which match the nutritional requirements of the larvae. This could be achieved by finding new methods of enrichment. Research in collaboration with Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has been carried out into developing enrichment methods using vitamin C, bacteria and fungi (7).

Rotifers: These multicellular animals are 200-300�m in length and are kept at a density of around 1500 per ml (3). They supply the nutritional requirements of fish larvae by retaining nutrients which are then passed on to the larvae (5), ensuring rapid growth.

As I go round, a putrid smell laces the air. Dark and bitter, it hangs heavily in the small room. The humidity makes it difficult to breath. Four tanks prevail to one side, overbearing. This is the live feed room of the Manx Mariculture fish hatchery. I peer closer to make out the reptilian green contents of the tanks. Here, rotifers, used as live feed, are grown in aerated tanks on a diet of yeast and algae at 25�C (3), optimum conditions for growth.

The cod and turbot larvae farmed at the site are reared on these for up to 20 days during which time it is not possible to produce food pellets small enough for their consumption. To small to be seen with the naked eye, rotifers are an excellent replacement of the fish’s natural diet, zooplankton (copepods) and they are enriched to supply the nutritional requirements of the larvae. Nutrition in the diet is essential in ensuring optimum growth.

Brine shrimps: With my knowledge of cod limited to its appearance in a plastic take-out box, the sight of the fish at 20 days, with their dark silken bodies deftly navigating the water, surprises me.

At this age, they are around 7-8 mm in length and are fed for a further 20 days on brine shrimp, or Artemia, 500-700 �m in length (3). By using a specially formulated diet for the Artemia, their nutritional content is increased to maximise the growth of the larvae. This also reduces pigmentation problems in the turbot, a species of fish I had not previously heard of. My first impression of them is that they bear a certain resemblance to the shape of a stingray. They line the bottom of the holding tanks, their slender bodies overlapping, producing a carpet of shimmering grey.

A tight ship: Nevertheless, live feed production is extremely expensive. To improve efficiency at Manx Mariculture, rotifer production is carried out as a continuous process. Future developments are needed in the production and reliability of rotifer and Artemia whilst reducing the cost of the feeds. Recent studies (Lubzens E, Zmora O, Barr Y, 2001) have shown that the rotifers, B. plicatilis and B. rotundiformis, are two species of rotifer most suited to mariculture.

Fish and chips – a change of diet

As cod are cannibalistic, grading is carried out at 2 to 4 months using filters of increasing width to separate out different sizes into different tanks. This increases the survival rate of smaller, weaker cod which may not have survived in the wild.

As it is not economically viable to produce live feed in large amounts as the fish mature, they are weaned off this and onto a diet of hard fishmeal pellets. This is achieved by gradually increasing the ratio of hard pellets to live food, fed once a day using automated feeders suspended above the tanks.

Made from smaller species of fish and crustaceans unfit for human consumption, standard fishmeal has a content of 65-67% protein and 12% fat (8). There may be some dispute over the validity of this data as it is from an internet site and the source is not clear, therefore it cannot be guaranteed that the information is entirely accurate. Fishmeal contains proteins, lipids, minerals and vitamins but very little carbohydrate. Its close composition to that of the fish’s natural diet makes it an excellent alternative (8).

Fishmeal increases feed efficiency and growth due to a greater nutrient uptake and absorption. It also provides a high amount of energy per unit weight (8). Lipids in the diet provide phospholipids and fatty acids required for optimum growth and development. They are also important in the structure and function of cell membranes. They can be easily digested and have a high energy content which is important as the diet contains little carbohydrate. This is most likely because there is limited availability of carbohydrates in marine environments (9). If the diet does not provide enough energy, protein needed for growth will be broken down instead which increases the costs of fish farming.

Protein is needed in the diet as it provides the 10 essential amino acids which the fish cannot synthesis. Fishmeal also contains minerals such as calcium, phosphorus and magnesium and vitamins including the B-complex (8). There are, however, ethical concerns over the use of fishmeal as some argue that for every tonne of farmed fish produced, 5 tonnes of fishmeal are used in the process. On the other hand, fishmeal can be seen to reduce pollution to the environment as there is increased nutrient uptake by the fish (8).

Green issues

Further environmental concerns which surround fish farming include the pollution caused by waste being discharged into the sea. However, made up of fish waste and undigested food, this is natural and it does not cause major problems or damage to marine environments (3). This likely to be accurate and precise information as Nick Fullerton is a professional with a degree in biology and has had many years experience in mariculture.

The energy cost of running the hatchery which includes pumping water 24 hours day and the continuous monitoring probes must also be taken into account when considering the environmental implications of fish farming.

A breath of fresh air

Continuing my tour, I am shown the large round tanks where the fish are held. A strange looking square device sits on the surface of the water. Consisting of a flimsy plastic frame, it looks unimportant, however, it has the potential to raise the survival of the fish by 90% (3). This is a surface skimmer which cleans the surface of the water by blowing air over it to remove the oily film which would otherwise build up.

When the surface is clear, young fish are able to gulp air in order to inflate the swim bladder, an organ in bony fish used for buoyancy. As the fish rely on the water in order to breathe and grow, the water quality can have a huge impact on the success of fish farming (10). The seawater in the hatchery is filtered through filters only 1 �m thick in order to remove most harmful bacteria and parasites and the continuous flow maintains the water quality (3). Bacteria such as Pseudomonas, Oceanospirillum, Marinobactera and Paracoccus are common in marine environments (11).

Much more impressive are the electronic probes which measure oxygen, carbon dioxide and ammonia levels and pH. However, water is not recirculated otherwise very strict controls would have to be enforced on water quality (3). Oxygen, required for aerobic respiration, is kept at a concentration of 8 mg per litre, or almost 100% saturation (At 20 �C, normal pressure and in freshwater, 9.1 mg/L = 100% saturation (12)). Fish require a high concentration of oxygen because they are very active and have a high metabolism. The oxygen concentration is increased when stress levels are elevated such as during transport. This causes the heart rate to increase and so the fish to take in more oxygen. Carbon dioxide levels are kept below 5 parts per million (ppm) and ammonia which is excreted by the fish is kept below 0.02 ppm. PH is ideally kept between 6.5 and 9.0 (10).

More advanced probes are being developed but these advancements are limited by cost. Temperature is kept around 7-8�C for cod and slightly warmer for turbot. These temperatures are maintained by 3 water inlets to each tank of cold, heated and ambient water. Hot water is not used due to the high cost, especially as the water is not recirculated.

Food for thought

The ethics of keeping the fish at high stocking densities needs to be considered, however, it can also be seen that their survival is much higher than in the wild. At 50 days, this is 20-30% compared with less than 1% in the wild (3). Turbot even appear to thrive at high densities (13) as this is natural to them in a marine environment on the ocean floor. This is likely to be valid information as it comes from an educational source although, published in 1992, it is not up-to-date.

Another concern is that if farmed fish escape and breed with wild stock, the genetic strain may be weakened as farmed cod have lost much of their natural awareness (3).

Help or hindrance?

Mariculture is growing worldwide at a rate of 5% annually (14) but is it actually accomplishing its aim of increasing fish stock? The use of fishmeal in fish farming means that it relieves pressure on one species only to transfer it to others. It can be argued that the numbers of other species of fish removed from the ocean in order to feed farmed fish mean that the problem is not solved. Furthermore, depleted stocks of other species may disrupt complex food webs in marine ecosystems as ‘population dynamics, competition for food and patterns of predation’ are changed (15).

Bacteriophages are actually viruses highly specialized to attack bacterial cells while doing no harm to animal cells. When a phage discovers a bacterium to which it possesses the correct key—that is, suitable receptors on the bacterial cell to which the phage can attach its tentacle-like extensions—then the phage will inject its hereditary DNA into the bacteria cell. Taking over the bacterial cell’s biochemical apparatus, the phage produces hundreds of phage copies, rupturing the cell. As the victim cell dies, the released phage copies attack any remaining bacterial cells like a pack of hungry wolves (Reidel).

Advantages The advantages of the therapy are obvious. Bacteriophages are very specific parasites and, unlike antibiotics, do not damage the useful bacteria that live in and on the body. Phages are “intelligent” medicine: They increase just where they are needed, while antibiotics often do not get to where they are needed. Once all phage-susceptible bacteria have been killed, phages are eliminated from the body. The most apparent benefit of phage therapy is that although bacteria are able to develop resistance to phages the resistance is much easier to overcome.

The reason behind this is that phages replicate and undergo natural selection and have probably been infecting bacteria since the beginning of life on this planet. Although bacteria evolve at a fast rate, so too will phages. Bacteria are most likely to modify the molecule that the phage targets, which is usually a bacterial receptor. In response to this modification phages will evolve in such a way that counteracts this change, thus allowing them to continue targeting bacteria and causing cell lysis.

As a consequence phage therapy is likely to be devoid of the problems similar to antibiotic resistance. Increasing evidence shows the ability of phages to travel to a required site — including the brain, where the blood brain barrier can be crossed — and multiply in the presence of an appropriate bacterial host, to combat problems such as meningitis. However the patient’s immune system can, in some cases mount an immune response to the phage (2 out of 44 patients in a Polish trial (Carson)).

Development and production is faster than antibiotics, on condition that the required recognition molecules are known. Disadvantages According to Reidel, the phages’ high specificity, with which they look for their bacterial victims, is at the same time also their therapeutic Achilles’ heel. Therefore, either a cocktail containing many different types of phages must be developed by the infection control specialist, or a phage effective against the specific pathogen of each patient must be custom-made through detailed microbiological analytical work.

Western regulatory authorities tend to loathe recognizing such manually manufactured anti-infective agents as medicines, which explains why currently phage therapy is routinely only available at phage therapy centers in Georgia (part of former Russia), Europe and Poland. However, the Wound Care Center in Lubbock, Texas, has started to treat patients. For chronic infections due to multi-resistant pathogens, phage therapy could become a kind of miracle medicine. Wikipedia condends that Bacteriophage therapy is generally very safe; however fevers can occur with phage treatment.

This is thought to be caused by endotoxins released by the bacteria within the patient after they have been lysed by the phage (Herxheimer Reaction), of course this can happen with antibiotics also. Additionally care has to be performed in manufacture that the phage medium isn’t contaminated with bacterial fragments and endotoxins from the production process. It is beneficial if testing on animals is performed to ensure safety. Lysogenic bacteriophages are also thought to be risky, and are now seldom used therapeutically.

These viruses can act as a way for bacteria to exchange DNA, and this can help spread antibiotic resistance or even, theoretically, can make the bacteria pathogenic. To work, the virus has to reach the site of the bacteria, and unlike antibiotics, viruses do not necessarily reach the same places that bacteria can reach. Finally, some non therapeutic (lysogenic) phages transfer genes between bacteria that code for pathogenicity, notable in cholera. This makes it important to identify the phages being used to show that they are not harmful ones. What are ANTIBIOTICS?

An antibiotic, according to Wikipedia, is a drug that kills or prevents the growth of bacteria. They have no effect against viruses or fungal infections. Antibiotics are one class of antimicrobials, a larger group which also includes anti-viral, anti-fungal, and anti-parasitic drugs. They are relatively harmless to the host, and therefore can be used to treat infections. The term, coined by Selman Waksman, originally described only those formulations derived from living organisms, in contrast to “chemotherapeutic agents”, which are purely synthetic.

Nowadays the term “antibiotic” is also applied to synthetic antimicrobials, such as the sulfa drugs. Antibiotics are generally small molecules with a molecular weight less than 2000 Da. They are not enzymes. Some antibiotics have been derived from mold, for example the penicillin class. Volume 4 of How Products Are Made says that antibiotics differ chemically so it is understandable that they also differ in the types of infections they cure and the ways in which they cure them. Certain antibiotics destroy bacteria by affecting the structure of their cells. This can occur in one of two ways.

First, the antibiotic can weaken the cell walls of the infectious bacteria, which causes them to burst. Second, antibiotics can cause the contents of the bacterial cells to leak out by damaging the cell membranes. One other way in which antibiotics function is to interfere with the bacteria’s metabolism. Some antibiotics such as tetracycline and erythromycin interfere with protein synthesis. Antibiotics like rifampicin inhibit nucleic acid biosynthesis. Still other antibiotics, such as sulfonamide or trimethoprim have a general blocking effect on cell metabolism. Advantages

It is estimated that the average duration of many infectious diseases and the severity of certain others have decreased significantly since the introduction of antibiotic therapy. The dramatic drop in mortality rates for such dreaded diseases as meningitis, tuberculosis, and septicemia offers striking evidence of the effectiveness of these agents. Bacterial pneumonia, bacterial endocarditis, typhoid fever, and certain sexually transmitted diseases are also amenable to treatment with antibiotics. So are infections that often follow viral or neoplastic diseases, even though the original illness may not respond to antibiotic therapy.

Antibiotics in small amounts are widely used as feed supplements to stimulate growth of livestock and poultry. They probably act by inhibiting organisms responsible for low-grade infections and by reducing intestinal epithelial inflammation. In cattle, sheep, and swine, antibiotics are effective against economically important diseases. The use of antibiotics in dogs and cats closely resembles their use in human medical practice. In fish farms, antibiotics are usually added to the food or applied to the fish by bathing.

The incidence of infections in fish, and animals in general, may be reduced by the use of disease-resistant stock, better hygiene, and better diet. Although effective against many microorganisms causing disease in plants, antibiotics are not widely used to control crop and plant diseases. Some of the limiting factors are instability of the antibiotic under field conditions, the possibility of harmful residues, and expense. Nevertheless, antibiotic control of some crop pathogens is being practiced, as is true of the rice blast in Japan, for example (Science and Tech). Disadvantages

Some individuals may have allergic reactions to antibiotics. If symptoms of an allergic reaction (such as rash, shortness of breath, swelling of the face and neck), severe diarrhea, or abdominal cramping occur, the antibiotic should be stopped and the individual should seek medical advice. Because antibiotics can affect bacteria that are beneficial, as well as those that are harmful, women may become susceptible to infections by fungi when taking antibiotics. Vaginal itching or discharge may be symptoms of such infections. All patients may develop oral fungal infections of the mouth, indicated by white plaques in the mouth.

Injected antibiotics may result in irritation, pain, tenderness, or swelling in the vein used for injection. It is a common assertion that some antibiotics can interfere with the efficiency of birth control pills. Although there remain few known cases of complication, the majority of antibiotics do not interfere with contraception, despite widespread misinformation to the contrary (Gale). And there’s also what is known as Antibiotic Resistance. Wikipedia says that Antibiotic Resistance is the ability of a micro-organism to withstand the effects of an antibiotic. It is a specific type of drug resistance.

Antibiotic resistance evolves naturally via natural selection through random mutation, but it could also be engineered for the purpose of creating bio-weapons. SOS response of low-fidelity polymerases can also cause mutation via a process known as programmed evolution. Once such a gene is generated, bacteria can then transfer the genetic information in a horizontal fashion (between individuals) by plasmid exchange. If a bacterium carries several resistance genes, it is called multiresistant or, informally, a superbug. Antibiotic resistance can also be introduced artificially into a micro-organism through transformation protocols.

This can be a useful way of implanting artificial genes into the micro-organism. Phages Vs Antibiotics (A Summary) Bacteriophages are great because: • Bacteria evolve at a fast rate, but so do phages. This makes Bacteriophages devoid of problems similar to antibiotic resistance. • Bacteriophages are very specific parasites and, unlike antibiotics, do not damage the useful bacteria that live in and on the body. Phages are “intelligent” medicine: They increase just where they are needed, while antibiotics often do not get to where they are needed.

• Development and production is faster than antibiotics. • The recovery rate was discovered to be faster in some cases—a tribute to the speed with which the phage multiplied and overcame its host bacteria. • Incidents of misuse are relatively unknown. Antibiotics are great because: • The use of antibiotics on domesticated animals, closely resemble its use in human medicine thus greatly benefiting them. • Phages work best when in direct contact with the infection, so they are best applied directly to an open wound.

This is rarely applicable in the current clinical setting where infections occur systemically. • Unlike Phages, which are hardly ever used for therapeutic reasons, antibiotics reduce the incidence of both suppurative and non-suppurative complications of sore throat. A new study from Holland has confirmed that antibiotics protect against quinsy. • Lysogenic bacteriophages are thought to be risky. These viruses can act as a way for bacteria to exchange DNA, and this can help spread antibiotic resistance or even, theoretically, can make the bacteria pathogenic.

To work, the virus has to reach the site of the bacteria, and unlike antibiotics, viruses do not necessarily reach the same places that bacteria can reach. • Antibiotics are more readily available because phages have high specifity and require detailed microbiological analytical work. Conclusion The research is still ongoing. Though the odds are in favor of Bacteriophages becoming more common, there have been no large clinical trials to test their efficacy. This therapy today essentially exists only in some Eastern European countries, including Georgia and Poland.

But largely because of the growing concern over antibiotic resistance, a lot more people in the medical field are interested in pursuing bacteriophages as an alternative to antibiotics on a large scale. W O R K S C I T E D 1. Reidel, William. “Book Review: Viruses vs. Superbugs: A Solution to the Antibiotics Crisis? ” Epoch Times. (6 May, 2006). 14 April, 2007. http://en. epochtimes. com/news/6-5-6/41280. html 2. Carson, Christine, and Thomas Riley. “Non-Antibiotic Therapies for Infectious Diseases. ” Communicable Diseases Intelligence Supplement on Antimicrobial Resistance 27 (2003): pages not given

3. “Phage therapy. ” Wikipedia, The Free Encyclopedia. 4 Apr 2007, 00:38 UTC. Wikimedia Foundation, Inc. 14 Apr 2007 <http://en. wikipedia. org/w/index. php? title=Phage_therapy&oldid=120112914>. 4. “Antibiotic. ” How Products Are Made. 2006. 14 April 2007 http://www. madehow. com/Volume-4/Antibiotic. html 5. Science and Technology Encyclopedia. New York: McGraw-Hill, 2007 6. Gale Encyclopedia of Cancer. Michigan: Thomson Gale, 2005 7. “Antibiotic Resistance. ” Wikipedia. Wikipedia, 2007. Answers. com 14 Apr. 2007. http://www. answers. com/topic/antibiotic-resistance

Mahogany used in multistory systems in the Philippines, boat and ship building and patternmaking. Logs are used for the manufacture of veneers and for paneling. It is also used as shade for coffee and cacao. Mahogany is regarded as the worlds finest timber for high-class furniture and cabinetwork. Its popularity is especially due to its attractive appearance in combination with ease of working,excellent finishing qualities and dimensional stability. Mahogany is also often used for interior trim suchas paneling, doors and decorative borders.

It is used for boat building, often as a decorative wood for luxury yatch and ocean liners, although it is also used when a medium-weight timber with other goodqualities is required. It is sometimes applied make it particularly suitable for precision woodwork suchas models and patterns, instrument cases, clocks, printer’s block and parts of musical instruments; for these purposes, uniform straight-grained material is used. Other minor uses include burial caskets, woodcarvings, novelties, toys and turnery.

BACKGROUND OF THE STUDY

Mahogany a large tropical tree with a symmetrical appearance, best-known for its valuableheartwood. The tree is also appreciated as a beautiful and useful street tree. A fast-growing, graceful,straight-trunked, semi-deciduous tree growing to 30-70ft. Most trees, particularly planted street treesgrow to 30-40ft. It looses its leaves just as new leafs sprout, so while deciduous, the tree is not withoutleaves for long. Tiny flowers are followed by 4-5″, woody fruits that burst open to expel the seeds. Mahogany is a valuable hardwood and this tree was once extensively harvested for its wood.

A relatedtree, S. macrophylla, now provides most commercial mahogany. The tree also makes an excellent streettree specimen in warmer climates as is popular for this purpose. Miami, Florida has numerousmahogany trees planted throughout the city for this purpose. The termites are a group of eusocial insects usually classified at the taxonomic rank of order Isoptera (but see also taxonomy below). Along with ants and some bees and wasps which are all placedin the separate order Hymenoptera, termites divide labour among gender lines, produce overlappinggenerations and take care of young collectively.

Termites mostly feed on dead plant material, generallyin the form of wood, leaf litter, soil, or animal dung, and about 10% of the estimated 4,000 species(about 2,600 taxonomically known) are economically significant as pests that can cause seriousstructural damage to buildings, crops or plantation forests. Termites are major detritivores, particularlyin the subtropical and tropical regions, and their recycling of wood and other plant matter is of considerable ecological importance. Their role in bioturbation on the Khorat Plateau is under investigation.

SIGNIFICANCE OF THE STUDY

Nowadays, people usually choose new innovations (features) to kill termites or any other pests. Pesticides are usually used to kill a particular target pest, many will also kill or harm species that thefarmer or other user is not targeting. For example, pesticides applied to crops might be washed intostreams or lakes and harm fish, beneficial insects, birds, or even find their way into drinking water sources. With this regard topic it includes improvement in human quality of life and lower food costs. Contributed significantly to improving the quality of life and safeguarding the environment.

STATEMENT OF THE PROBLEM

It should be only used and tested in termites.

B. CONCEPTUAL FRAMEWORKHYPOTHESIS

Mahoganyseed extract Used a stermiticide tokill termites

OBSERVATORY;

On Savanna, Termites Are a Force for Good By SINDYA N. BHANOO

Published: June 1, 2010

The African savanna has a cornucopia of majestic creatures — lions, elephants and giraffes amongthem. But behind the scenes, it is the tiny termite that fuels much of this diversity, a new study reports. Researchers studying termites in Kenya’s central highlands found that the abundance of flora andfauna is markedly higher atop termite mounds.

”We noticed these circular green patches,” said Todd Palmer, a co-author of the study and a professorof biology at the University of Florida. ”They had a lot of vegetation and plant material on top of them,and the grass was greener than in other areas. ”The patches were 30 feet in diameter and spaced several hundred feet apart. Dr. Palmer and his colleagues did some digging, and underneath each patch they found millions of termites in subterranean mounds. Quantitatively, they found that plants grow about 60 percent largeron the patches compared with other areas.

The nitrogen content of the plants on the mound is about20 percent higher, and trees on mounds bear 120 percent more fruit. Animal populations also droppedoff significantly the farther they were located from a patch. Termite mounds are rich in nutrients like nitrogen and phosphorus, and termites also help loosen soilto promote water absorption, Dr. Palmer said. Other animals visit the lush patches to eat and end updefecating and urinating there, adding their own nutrients and triggering more plant growth. In the human world, termites are seen as pests for their remarkable ability to eat into dead wood.

Butin the animal kingdom, Dr. Palmer said, this is what makes them so desirable. ”They are basically consuming dead wood and plant materials,” he said. ”In their absence, that would just lie there and there would be no way to break down the organic material and convert it to nitrogenand phosphorus. ”How Termites Live on a Diet of Wood By NNIICCHHOOLLAASSWWAADDEE Published: November 14, 2008 If only wood could be converted tobbiioof f uueellss, there would be no need to wait a million years for thetrees to be buried and become oil. Wood is

indeed convertible to useful chemicals, because termitesdo it every day, causing $1 billion of damage every year in the United States. But to live on a diet of wood is challenging, not least because wood contains so little nitrogen. So how do termites do it? Visual ScienceScientists rely on graphics and other visuals to present their findings to the world. This feature takesraw graphics from various scientific journals and unpacks the stories they tell. The trick lies in a cunning triple symbiosis, a team of Japanese scientists report in Fridays issue of Science.

In the termites gut lives an amoeba-like microbe called a protist, and inside each protist livesome 10,000 members of an obscure bacterium. The microbes in the termites gut are very hard to cultivate outside their termite host and so cannot bestudied in the lab. The Japanese scientists, led by Yuichi Hongoh and Moriya Ohkuma at the RIKENAdvanced Science Institute in Saitama, have cut through this problem. They extracted the protistsbacteria directly from a termites gut, collected enough to analyze their DNA, and then decoded the1,114,206 units of DNA in the bacteriums genome. WEDNESDAY, FEBRUARY 28, 2007

Entomologists discover cellulase genes in termite gutS As scientists search for alternatives to fossil fuel, producing chemical energy from wood fiber has become a big challenge. Several research organisations and biotech companies are trying to discover enzymes that break down cellulose into glucose in an efficient way (earlier post). However, termites have been working this alchemy for millions of years. A University of Florida (UF) study published last month in the journal Gene sheds new light on the mysterious and complex process that enables the insects to eat the cellulose, the main structural component of plant cells.

For people and most animals, cellulose is indigestible, but termites break it down easily into glucose, a form of sugar most organisms need. These sugars can be fermented into bio-products, such as ethanol or bioplastics. The study identifies four genes that produce enzymes responsible for taking cellulose molecules apart in a process called cellulase (picture, click to enlarge) insight that could lead to breakthroughs in energy production and pest control, said Michael Scharf, an assistant research scientist with UF’s entomology department and a co-author of the paper.

The scientists looked at the dominant termite species in the U. S. but they are sure they haven’t identified all the genes involved in producing these enzymes yet. Only one of the genes actually belongs to the insect researchers studied, the eastern subterranean termite. The other three belong to microscopic organisms known as symbionts that live inside the termite’s digestive system: “The termites provide the symbionts with a home, and the symbionts pay the rent by producing enzymes,” says Sharf. Altogether, there may be hundreds of cellulose-digesting enzymes produced by the termites and their tiny tenants, Scharf said.

One potential payoff from the research is that scientists may be able to transfer specific enzyme-producing genes into bacteria, then culture them to produce large quantities of enzymes to make ethanol from wood scraps and other fibrous materials, he said. Known as cellulosic ethanol, this fuel has gained worldwide attention because it doesn’t require edible material such as corn, used in conventional ethanol production. The interaction of multiple genes makes cellulose digestion an efficient process in termites, but scientists want to pin down enzyme combinations that will digest cellulose affordably, Scharf said.

Many genes remain undiscovered, and UF researchers have applied for funding to support a massive effort to identify all cellulose-digesting genes in the eastern subterranean termite and its common symbionts. Greater genetic knowledge could also aid in termite control, an important issue in Florida, which accounts for about one-third of control efforts in the United States, said Phil Koehler, a UF entomology professor and co-author of the paper. By identifying enzymes most crucial to termite digestion, scientists may be able to kill the insects by shutting down selected genes, he said.

Termite-control strategies, such as bait systems or treated lumber, would be environmentally friendly because they would have no effect on organisms that don’t eat cellulose, he said. “Anything we do with this kind of work will reduce the need for conventional pesticides,” Koehler said. Development of enzyme-blocking products could happen but will require attention to termite behavior, said Brian Forschler, an entomology professor at the University of Georgia in Athens. Recent research shows that termites, which live in colonies that can number 1 million, often consume partially digested material excreted by their compatriots, he said.

So it would be important that bait products not disrupt termites’ feeding behavior. If it did, termites might avoid an enzyme-stopping bait and instead share more partially digested food. “You just have to remember that you’re dealing with an entire termite colony,” Forschler said. “This research holds a great deal of promise. ” Further termite genetics research could reveal effective methods of disrupting termite social behavior, perhaps in ways that cause the insects to die, said Faith Oi, an assistant extension scientist with UF’s entomology and nematology department.

“The model for exploiting the termite’s social behavior for control is not new,” said Oi, another co-author of the paper. “In terms of pest control, we can look to this area of science enhancing existing methods. ” Bed Bug Herbal Remedies Work Well With Traps July 15, 2013 THE NEEM TREE (Azadirachta indica), a medicinal mahogany tree (Meliaceae) native to arid broadleaf and scrub forests in Asia (e. g. India), has been used for over 4,000 years in Vedic medicine and has a heavy, durable wood useful for furniture and buildings because it is resistant to termites and fungi.

Nonetheless, despite US EPA registration as a pesticide for crop and home use and a long legacy of neem seed oil use for cosmetics, shampoos, toothpastes and medicines in India, Ohio State University researcher Susan Jones could not find any households near her Columbus, Ohio, home willing to try neem in her bed bug control experiments. “We had no study takers because of the regulatory requirements,” which scared off people, Jones told the Entomological Society of America (ESA) Annual Meeting.

“You have to read page after page to residents about toxicity without being able to talk about the toxicity of alternative products” not as safe as neem. In October 2012, an empty house with bed bugs became available for research when its occupant opted to escape a bad bed bug infestation by leaving the infested home; and inadvertently transferred the infestation to their new home. Jones monitored the empty house by placing in each room four (4)Verifi(TM) CO2 (carbon dioxide) traps and four (4) Climbup(R) Interceptor traps. Visual inspections revealed few bed bugs.

On October 24, 2012, prior to neem treatments, 38 bed bugs were captured in Climbup(R) traps, indicating bed bug infestations only in the master bedroom and bed of the empty house. Eight Verifi(TM) traps captured 48 bed bugs in the dining room, guest room and master bedroom. As part of an IPM (integrated pest management) approach using multiple treatment tools: Electrical sockets were treated with MotherEarth(R) D diatomaceous earth; 3. 67 gal (13. 9 l) at a rate of 1 gal/250 ft2 (3. 9 l/23 m2). Gorilla Tape(R) was used to seal around the doors and exclude bed bug movement from other rooms.

The neem seed oil product, Cirkil (TM) RTU, was sprayed in various places, including on books, backs of picture frames and cardboard boxes. Vials of the insecticide-susceptible Harlan bed bug strain were placed around the house for on-site neem seed oil vapor toxicity assays. Two days after spraying, bed bug mortality from neem seed oil vapors was highest in confined spaces; with 48% mortality in vials placed between the mattress and box spring, versus 28% mortality in open spaces. On Nov. 6, two weeks post-treatment, 123 dead bed bugs were vacuumed up and live bed bugs were detected in a second bedroom.

Bed bug numbers were low because the monitoring traps were doing double duty, also providing population suppression by removing many bed bugs. Herbal oils can also be combined with heat chambers at 50 C (122 F) or carbon dioxide (CO2) fumigation chambers to combat bed bugs. However, heat chambers are expensive, and CO2 fumigation with dry ice can pose handling difficulties and room air circulation issues, Dong-Hwan Choe of the University of California, Riverside, told the Entomological Society of America (ESA).

Herbal essential oils are useful against head lice, and in Choe’s native Korea clove oil from from the leaves and flower buds of clove plants (Syzygium aromaticum) is used in aromatherapy and as a medicine. Clove oil is rich in GRAS (Generally Recognized as Safe) compounds such as eugenol, beta-caryophyllene and methyl salicylate (sometimes called wintergreen oil), which are useful as vapors in control of insects and microbes. In dentistry, clove oil (eugenol) is widely used as an antiseptic and pain reliever.

Clove essential oils work faster in closed spaces or fumigation chambers (e. g. vials, Mason jars) than in open spaces. Essential oils are even slower to kill bed bugs when orally ingested. In experiments at varied temperatures, Choe placed 10 bed bugs in plastic vials with mesh tops. The vials were placed inside 900 ml (1. 9 pint) Mason jars; filter paper treated with essential oils was placed on the underside of the Mason jar tops. Herbal essential oils worked faster at higher temperatures.

For example, methyl salicylate fumigant vapors provided 100% bed bug mortality in 30 hours at 26 C (79 F); 10 hours at 35 C (95 F); and 8 hours at 40 C (104 F). Eugenol vapors produced similar results; there were no synergistic or additive effects from combining eugenol and methyl salicylate. Choe told the ESA that his future trials will include: botanical oil granules; exposing bed bug-infested items to essential oil vapors; and checking for sublethal essential oil effects on parameters such as female bed bug reproduction.

Narinderpal Singh of Rutgers placed bed bugs on cotton fabric squares treated (half left untreated) with synthetic pesticide and herbal essential oil products: 1) Temprid(TM) SC, a mixture of imidacloprid and cyfluthrin (neonicotinoid and pyrethroid insecticides); 2) Ecoraider(TM) (Reneotech, North Bergen, NJ) contains FDA GRAS ingredients labeled as “made from extracts of multiple traditional herbs that have been used in Asia for hundreds of years for therapy and to repel insects;” 3) Demand(R) CS, which contains lambda-cyhalothrin (a pyrethroid insecticide); 4) Bed Bug Patrol(R) (Nature’s Innovation, Buford, FL), a mixture with the active ingredients listed as clove oil, peppermint oil and sodium lauryl sulfate. && Temprid(TM) SC and Demand(R) CS proved best on the cotton fabric test. In arena bioassays with Climbup(R)Interceptor traps, none of the four insecticides were repellent to bed bugs (i. e. repellency was less than 30%). Ecoraider(TM) was equal to Temprid(TM) SC and Demand(R) CS against the tough to kill bed bug eggs. Singh concluded that field tests of Ecoraider(TM) as a biopesticide were warranted.

Changlu Wang of Rutgers told the ESA that travelers might be protected from bed bug bites and bring home fewer bed bugs if protected by essential oil repellents, as well as by more traditional mosquito and tick repellents like DEET, permethrin and picaridin. Repellents are more convenient and less expensive than non-chemical alternatives such as sleeping under bed bug tents and bandaging yourself in a protective suit. Isolongifolenone, an odorless sesquiterpene found in the South American Tauroniro tree (Humiria balsamifera), is among the botanicals being studied, as it can also be synthesized from turpentine oil and is as effective as DEET against mosquito and tick species.

Bed bug arena tests involve putting a band of repellent around a table leg, with a Climbup(R)Interceptor trap below. If the bed bug falls into the trap, it is deemed to have been repelled from the surface above. In actual practice, the bed bug climbs up the surface and goes horizontal onto the treated surface and drops or falls off if the surface is repellent. Isolongifolenone starts losing its repellency after 3 hours; 5%-10% DEET works for about 9 hours. In arena tests with host cues, 25% DEET keeps surfaces repellent to bed bugs for 2 weeks. But isolongifolenone is considered safer, and Wang is testing higher rates in hopes of gettting a full day’s protection. How to Kill Termites: Treatment Options for Homeowners

Don’t let their size fool you, termites are far from harmless. These small white insects feed on untreated wood piles around homes and can even start up a colony within the structure of your home–where wood is abundant. When termites find their way into homes, they can cause serious structural damage that requires costly repairs. If you’re wondering how to kill termites, contacting a professional to address the problem is the best treatment method you can choose to maintain the integrity of your home. There are different methods you can use to kill termites around your home, but remember that your safest option is to contact a professional to treat your home and property.

If you’re waiting for your exterminator to come and inspect your home and you want to be proactive, there are a couple of different treatment options you can try. 1. Boric acid- This white powder is commonly used to kill roaches, but it works with termites as well. You can sprinkle it around the foundation of your home to keep termites from coming in. You’ll need to repeat this treatment every few days for at least two weeks before you notice a decline in the number of termites in your home. 2. Bait blocks-You can also place bait blocks around your home. You can find these in most grocery or hardware stores. These traps contain wood that’s been treated with pesticide.

Once the termites find these traps, they’ll carry the poisoned wood back to the queen. Once the queen dies, the termites will be unable to reproduce. 3. Termiticide- If you know the location of the infestation, you can spray the area with a non-repellant termiticide, or you can sprinkle the area with Bio-Blast. Termites that come into contact with pest control products will infect other termites until that infection reaches the queen. However, it may take up to three months before your termite problem is under control. Home treatments can be less expensive than hiring a professional exterminator, but if you don’t treat the problem properly, termite damage can be costly.

Your safest option is to contact a professional if you have any suspicion that termites are present. Contacting a professional to treat your termite problem as soon as possible can help you prevent much of this damage and save you from costly repairs. If you have a termite problem, contact one of the pest control experts at Landscaper. org to take care of the problem before it becomes worse. Research Article Termiticidal Activity of Parkia biglobosa (Jacq) Benth Seed Extracts on the Termite Coptotermes intermediusSilvestri (Isoptera: Rhinotermitidae) Bolarinwa Olugbemi Division of Termite Control and Ecology, Termite Research Laboratory, P. M.

B. 656, Akure 340001, Nigeria Received 5 October 2011; Revised 14 November 2011; Accepted 28 November 2011 Academic Editor: Arthur G. Appel Copyright © 2012 Bolarinwa Olugbemi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract The chemical and mineral composition of raw and boiled seeds of the African locust bean, Parkia biglobosa (Jacq) Benth, was determined while the termiticidal action of the aqueous, alcoholic, and acetone extracts of the bean seeds were investigated.

Variations in the proximate and mineral composition of the raw and boiled seeds were obtained while heavy minerals such as cadmium, cobalt, lead, nickel, and copper had been leached out of the seed during the process of boiling. Extracts from the raw seeds exhibited varying degree of termiticidal activity, while extracts from the boiled seed had no effect on the workers of Coptotermes intermedius Silvestri. Alcoholic extracts were more active than the aqueous and acetone extracts. Termites die within 30?min, 40?min, and 110?min when exposed to concentration of 4?g?mL?1 treatments of alcoholic, aqueous, and acetone extracts, respectively. 1. Introduction Termites cause the most serious damage of all wood-feeding insects.

In addition to timber and wood products, they attack growing trees, leather, rubber, and wool as well as agricultural crops [1]. Significant damage is caused by termites to man-made fabrics, polythene, plastics, metal foils, books, furniture, wooden telephone poles, wooden railway sweepers, and insulators of electric cables [2]. Damage caused by termites to wooden structures in the United States of America is estimated to be over 3 billion Dollars annually, with subterranean termites accounting for at least 80% of these damages [3]. Costs attributable to Coptotermes formosanus in the Hawaiian Islands alone are greater than 60 million Dollars per annum [4].

Termites are so destructive in that they derive their nutrition from wood and other cellulotic materials. In Africa and elsewhere in the developing countries, there is hardly any data on either the quantum of damage done by termites to agricultural crops, construction timbers, paper, and paper products, or the cost of control or repairing the damage done by these insect pests. The damage done by various termite species in Nigeria [2] ranged from scavenging on tree barks and dead branches, to eating out grooves in the roots and stems of plants. Past research efforts had focused more on chemical methods of control, with an obvious lack of attention placed on understanding the behavior and history of these termites.

In view of mounting concerns over the side effect caused by the use of these toxic and environmentally unfriendly chemicals, direction of research is now focusing on alternative nontoxic, biological, and environmentally friendly methods of control. These methods include baiting systems, use of asphyxiant gases, application of extreme temperatures, barriers of various types, as well as biological control organisms [3, 5]. Extractives with insecticidal properties from naturally resistant wood and plant species in form of phenolic, terpenoid, and flavonoid compounds, show great promise for prevention of termite attack [6–9]. Some of these substances may also act as feeding deterrent [10–12].

The termite Coptotermes formosanus was found to be attracted and preferentially feed upon the amino acids, glutamic and aspartic acids [13]. These could be used to improve the effectiveness of baiting systems. Many of the chemicals causing attraction and avoidance in several tree species are polar molecules [14]. Investigation has shown that steaming of the heartwood of the Japanese larch, degraded or removed the chemicals responsible for the inhibition of termite attack [15]. A number of tree species such as the Alaska cedar, redwood, and teak [16] are resistant to termite attack. Neem was found to be a strong repellent to Coptotermes formosanus and was suggested as a barrier tree to protect more vulnerable plants [17].

The use of high levels of carbon dioxide, for extended period of time has been successfully used to control termites in contained spaces [4]. The application of heated air to kill termites has shown to be successful in laboratory bioassays [18]. Liquid nitrogen has also been shown to be effective in eliminating termites in the laboratory [3]. These temperature-based control methods are showing great promise, but need more field studies on their effectiveness in natural settings. In other studies [19] Inundation with water was shown to cause a decline in foraging worker population. This could indicate possible applications to control, for example, the controlled flooding of the territories of specific termite colonies to reduce damage by foragers.

Barriers to foraging termites that are being tested include sand, crushed granite, glass splinters, and metal shields. These methods have had mixed successes, thereby pointing to the need for more research in this area [3]. The African locust bean, Parkia biglobosa (Jacq) Benth, is a perennial leguminous tree, found growing wildly in forested and savanna belts in Nigeria. Fermented Parkia seeds are locally used in traditional soup seasoning, medicinal preparations and food additives [20]. In addition, boiled water obtained during fermentation process of P. biglobosa seeds is used in controlling termite infestation at the local level. In spite of this practice, few reports exist on the termiticidal properties of aqueous solution of P. biglobosa seeds.