HUNTINGTON'S DISEASE

Huntington's disease, also known as Huntington's chorea is a genetic disorder that usually shows up in someone in their thirties and forties, destroys the mind and body and leads to insanity and death within ten to twenty years. The disease works by degenerating the ganglia (a pair of nerve clusters deep in the brain that controls movement, thought, perception, and memory) and cortex by using energy incorrectly. The brain will starve the neurons (brain cells), and sometimes make them work harder than usual, causing extreme mental stress. The result is jerky, random, uncontrollable, rapid movement such as grimacing of the face, flailing of arms and legs, and other such movement. This is known as chorea. Huntington's chorea is hereditary and is caused by a recently discovered abnormal gene, IT15. IT stands for "interesting transcript" because of the fact that researchers have no idea what the gene does in the body. Huntington's disease is an inherited mutation that produces extra copies of a gene sequence (IT15) on the short arm of chromosome 4. A genetic base that exists in triplicate, CAG for short, is effected by Huntington's disease. In normal people, the gene has eleven to thirty-four of these, but, in a victim of Huntington's disease the gene exists from anywhere between thirty-five to one-hundred or more. The gene for the disease is dominant, giving children of victims of Huntington's disease a 50% chance of obtaining the disease. Several other symptoms of the disease exist other than chorea. High levels of lactic acid have been detected in patients of Huntington's disease as a bi-product of the brain cells working too hard. Also, up to six times above the normal level of an important brain brain protein, bFGF (or basic fibroblast growth factor) in areas of the brain effected by the chorea. This occurs from the problems on chromosome 4, where the gene for control of bFGF is also located. As of yet, there is no treatment for Huntington's disease. But with the discovery of the mutated genes that cause it, there is now a way of diagnosing if you will get it. This technique was discovered only recently and reported in the Journal of American Medical Association in April, 1993. Something that many people do not want to know. Because it can go two ways. Either you are extremely relieved because the test shows up negative, and a great burdon is lifted off of your mind, or you show up positive, and know how and a little bit about when you will die, increasing the burdun very greatly. And living the rest of your life in depression. Some 30,000 Americans are currently suffering for this genetic disorder. Named in 1872 for George Huntington the New York Doctor who first wrote down it's devestating symtoms, Huntingtons disease up to now was a silent time bomb. 13,000 people, the largest known concentration of sufferers from Huntington's Disease, live in the Lake Maracaibo region of Venezuela. The origins of this gene pool has been traced back to the 1800's to a woman named Maria Concepcion. It was from blood samples of these people that scientists became extraordinarily lucky and isolated the genetic marker that shows the presence of this disorder. Today, it is believed that Maria obtained the disease when she was birthed by a european sailor. Since it was first recorded by George Huntington, a Long Island doctor, Huntington's disease had remained fairly low key. No one heard about it until it infected Woodie Guthrie, A famous folk singer from the 1920's who showed symptoms of the disease. In 1967, he died. This put Huntington's Disease on the map, but it still was not well known. But, before Woodie guthrie died, he had a son, Arlo Guthrie. He, too became a famous folk singer, this time from the Seventies. He became extremely famous, but had to live with the fact that he has a 50% chance of having the disorder. That aroused huge public interest and made the disease well-known. Now that you know about Huntington's disease, you can imagine how it works, and the probability of getting it. But, can you imagine how it feels to have the disorder? What would it be like to know that you have a 50% chance of not reaching your sixtieth birthday? Now, enter the life of Nancy Wexler, a woman who knows how it feels for both of these. She watched as her mother died from the disease, and has to live with the fact that she may be next. When Wexler was young, three of her uncles died of the killer disease. "Men only got Huntington's disease" went the myth. Then it happened; her sister was told by her doctor that her unusual walk was an early symptom. She too had the disease. Since then, she and her sister Alice, swore never to have children. Years later, Wexler joined up with her husband Milton Wexler, and Marjorie Guthrie, wife of Woodie Guthrie, and formed the Los Angeles chapter of the Commitee to combat Huntington's Disease. Guthrie wanted to focus the organization on patient care, but Wexler was intent on finding a cure. So, she began to invite biologists to help study the disease while she worked to get her Ph.D. In 1976 she moved to Washington to become executive director of the Congressional Commission for the control of Huntington's disease and it's Consequences. Once there, they discovered that Huntington's disease works by distroying the Ganglia. Then they decided that the best way to research Huntington's disease was at the level of the gene. They decided to loook for a "marker" (small identifiable piece of DNA) of where the faulty gene is located. This normally would yave taken 50 to 75 years to find. But, on a freak chance, they found it. it was the 12th marker that they tested. The discovery of the marker led to the discovery of the gene which won Wexler the Albert Lasker Public Service Award. The highest honor in American medicine. She also developed a test to accurately determine whether or not someone will get Huntington's disease. Wexler will not reveal if she, herself has taken the test because she does a multitude of genetic counciling, and does not want to sway her patients' decisions on whether or not to take the test. But, whether she tests positive or negative, Huntington's disease will live on. Unless scientists like Wexler can find a cure.

Homo Aquaticus

I. Introduction When the human brain is compared with the brains of apes there are several obvious differences; the centers for the sense of smell and foot control are larger in apes than in humans, but the centers for hand control, airway control, vocalization, language and thought are larger in humans. In my paper, I will describe the most defined differences of brain size and centers between humans and their closest relatives, chimpanzees, to compare them with other mammals and to draw conclusions about the evolution history of humans. II. Brain Evolution Humans and chimpanzees are biochemically (DNA) and therefore probably phylogenetically (evolution relationships), more alike than chimps and gorillas. But the brains of chimps and humans differ in size and anatomy more than gorillas and chimps. The brains of chimps and gorillas probably didn't go through many evolutionary innovations, because they generally resemble other ape and monkey brains. This implies that the human brain changed a lot after the human/chimp evolution. With the exception of the olferactory bulb (scent), all brain structures are larger in humans than in apes. The neocortex (part of the cerebral cortex), for instance is over three times larger than in chimps, even though chimps and humans are pretty close to equal in body weight. Each side of the brain is diveded by the central sulces into independant halves. Just before the central sulcus lies the post-central cortex, where the opposite body half (right side for left brain, left side for right brain). Just in front of the central sulcus lies the pre-central cortex where the information for the voluntary movements leave tthe brain. The pre-central area is called primary motor cortex, and also "Area 4" in primates. III. Human and Chimp Cortex Differences In humans Area 4 is almost twice as large as it is in chimpanzees. The part of Area 4 that commands the movement of the leg, foot and toes is smaller in humans than apes. This leaves more room for the part that controls the hand, fingers and thumb. Even bigger is the lower part of human Area 4, related to the mouth and brething and vocal cords. The post central cortex is enlarged the same as Area 4. In front of the primate Area 4 lie the cortex areas (pre-motor) that tell Area 4 what to do. In front of the enlarged part of human Area 4 is the Area of Broca, the motor-speech center which controls the breathing muscles. Above Area Broca is Wernicke's Area, the speech center, a uniquely human brain center along with Area of Broca. Wernicke's Area has direct connections to Broca's Area through arcuate fasciculus, a neural pathway that apes don't have anywhere in their brain. The major difference between the human and ape cortex's is the enlargement of the hand and mouth integration areas. These areas occupy a large part of the human brain.ý In the motor half of the cerebral cortex, enlarged areas are in the pre-motor area and Broca's Area. In the sensory half, the enlarged ares are Wernicke's Area and the visual area as well as the auditory cortex.ý IV. Explanations Many anthropologists believe that the differences between human and ape brains are shown through man's ability to use tools and language. This traditional view cannot explain why only human ancestors developed these motor skills and language abilities, that is, why nonhuman primates and other savannah mammals didn't develop these abilities. The solution may lie in the aquatic theory of human evolution, the theory that explains why humans don't have fur, and why we have excess fat, and many other human features.(4) There are indications that the early hominoids (ancestors to man and ape) lived in mangrove or gallery forests(5), where they adapted to a behavior like proboscis monkeys, climbing and hanging in mangrove trees, wading into water and swimming on the surface. In my opinion human ancestors, split from chimpazees and other apes and, instead of staying in forests like chimps, progressed with their water skills, like diving and collecting seaweed, then adapted to waders in shallow water and finally to bipedal walkers on land. The fact that human olfactory bulbs are only 44% of the chimpanzee bulbý, is not compatible with African savanah life. All savanah animals have a good olfaction. But an aquatic evolutionary phase would explain why humans have a poor sense of smell. Water animals typically have a reduced or even non-existent sense of smell.(4) The human Area 4 for the legs, feet and toes are reduced, because human left the trees and lost the grasping hind limbs of apes. Area 4 for the hands and fingers are larger than apes. The human hand is much more mobile than an apes, the thumb and index finger in particular, the human fingertips are more sensetive, we have faster-growing fingernails. All of these enhancements point towards the enhanced hand mobility and sensitivity of raccoons and sea otters, which suggests that human ancestors groped for crayfish and shellfish underwater, also the mobility was needed to remove the shells of the food. Raccoons are good climbers but seek most of their prey in shallow water. They have human like forelimbs and fingersý. And their brain cortex shows the same types of enlargements as humans. Sea-otters, humans, and mongrove monkeys all use tools, unlike savannah mammals.(5) Like humans, all diving mammals have excellent airway control, to keep the water out of their lungs. This voluntary control of breathing is necessary because they have to inhale strongly before they dive, and under water they have to hold their breath until they surface. In land mammals, however, exhaling and inhaling breathing rythms change involuntarily. with lower oxygen and higher carbondioxide. An aquatic mammal with that mechanism would inhale strongly when its need for oxygen was the highest, in other words, it would inhale involuntarily while underwater. That's why the human ancestor tripled the part of Area 4 for the mouth and airways, and why he evolved the Broca area which coordinates the muscles of the mouth airways. This refined airway control was a preadaptation for human speech.(4) V. Speech and Association Areas The arcuate fasciculus in humans directly connects the coordination center of the muscles needed for breathing (Broca) with the cortex behind the sensory areas for the mouth and throat (where we feel the movements our breathing, singing, talking etc. make) and the audio areas (where we hear and register the sounds we hear)(5). This connection of airway sensation with hearing was the beginning of learning to make voluntary sounds. In the primitive' part of Wernicke, the first interpretations of sound are made possible through connections to the visual and paretial areas, so that the sounds were associated with what we were seeing and feeling when we heard the sound. Once the connection of Wernicke and Broca was made, we got a device that could both make sound and interperet it. Using that apparatus we learned to communicate with the others living in our group. We bettered our communication abilities by evolving larger areas for the use of our new mechanism. Apes lack the association ares. Any ape could have evolved a greater amount of brain tissue and developed the larger association areas, if the ape had found a need for the extra brain. But, the larger association areas were useless without the improved sound making/interpereting areas found in humans. Voluntary and variable sound production seen in aquatic animals like otters, seals, sea lions, and toothed whales. Large brains are a feature of many aquatic animals, seals and toothed whales. The relation between aquatic life, brain size and vocal control is not clear. But even the small-brained sea mammals have fairly well-developed vocalization skills. VI. Brain Lateralization An important difference between a human brain and an ape's brain is the larger amount of asymmetry in human brains. Like humans being right-handed, is more pronounced than dexterity of monkeys or apes.(4) Most mammals and birds show small signs of asymmetry in certain brain functions. The left part of the brain, in most people, is larger than the right half. (Remember that the left half of the brain controls the right half of the body and vice versa.) In 65% of people, the left planum template, where the hearing centers are, is much larger than the right one. Musical learning that occurs before the age of seven seems to induce strong enlargement of the left planum temporale. In more than 80% of people the same hemishpere controls the dominant hand (right). Why is that? The right hand is usually the hand that does things with an object while the other hand holds the object steady. The left hand holds the shield, holds the billiard cue, and holds the paper when writing. This fits with the spatial and geometricality of the right hemishpere. The right hand is not completely dominant, there is a small division of tasks between the left and right brain centers for the hands, especially with jobs that two hands have to be used in. Some people say that our dexterity came from an ancestor that picked fruit with one hand while stabalizing himself by holding onto a branch with the other hand. Although apes are sometimes right or left-handed for certain tasks, systemetic handedness in the human sense has hardly been demonstrated so far in nonhuman primates. One explanation for humans having more refined dexterity than apes is that diving homonids used the right hand to get shellfish from the bottom of waters while the left grasping something to keep them on the bottom. Or they used a rock to open the shell while the left held the mussel or oyster etc. That could be the beginning of human tool use. Hands are paired organs. Each hand needs its own control center in the brain. The two centers can be symmetrical -- like apes or, like humans when each hand has a different function -- more or less asymmetrical. However, an unpaired organ works better if it has one brain center dominating over the other, so that fine movements would not be messed up by commands from the other brain center. A good coordination of the breathing muscles would be essential, the need for dominant brain centers made dominant brain centers. Song production in birds is strongly asymmetrical. In adult finches, section of the left nerve for the syrinx leads to the loss of most of the song, but the right section has only minor effects of song loss. If the left nerve is cut before song develops, the right takes over completely. Human speech centers, too, show a great deal of plasticity. The localization of Braca's and Wernicke's Area in the left hemishpere is more constant than human dexterity: not only right- handers, but also most left-handers, have their speech centers in the left hemisphere of their brain. Is there any relation between right/left-handedness and the location of the sound- interpereting/making device? The fact that the control of our dominant hand is usually situated on the hemisphere of speech centers could mean that the earliest language use in human ancestors were the naming of objects that were manipulated or pointed at with the right hand. Or is it simply cooincidence. VII. Conclusions The changes in human brain anatomy, compared with the brain anatomy of apes and monkeys, fits with the aquatic theory of human evolution and have relationships with aquatic and semiaquatic mammals. Reduced olfaction is typically seen in aquatic mammals. Diminished foot control is a feature of nonarboreal (not living in trees) mammals. Very refined finger control is a feature of shallow-water feeders. Perfect control of the airway entrances is essential in diving mammals. Elaborated vocal ability is seen in aquatic mammals. A large brain is seen in aquatic mammals such as seals and toothed whales. Brain asymmetry leads to an aquatic ancestor in human evolution history. Result: Homo Aquaticus? I think so. And I thik I have proved to myself well enough to believe in the theory.

Becoming an Ecologist is an Exciting Venture

Because of the increasing changes in the environment, a career as an ecologist is an important venture, especially for an earth-science oriented person with a love for nature and animals. With the number of ecological disasters escalating every year there is an ever increasing need for ecologists and people trained in ecology. Along with these disasters there are hundreds of animals and plants that are disappearing off the planet everyday. There is also an increasing demand for a person with the training to take care for, rehabilitate and then return to the wild injure animals, which is the prime responsibility of an ecologist. Ecologists mainly study the ways in which mankind is destroying the natural ecosystems of the earth and how people can help to revive them. Louise Miller once said that,". . . the ecologist is the one that brings together the study of all natural systems- earth, air, water, plants, and animals. Connections between living organisms and effects of their interactions are ecologists' concerns. . . . .The balance of nature, wherever it occurs, is what you will investigate and analyze"(17). Since a career as an ecologist is usually long term, there are certain characteristics a person should have in order to maintain a successful career. One of these characteristics that is the most important is patience. Patience is important because as an ecologist a person will have to at some point in their career talk to another person who knows nothing of or about ecology. Another reason why patience is important is because through the first years of being an ecologist finding and possibly attempting to tag an animals or gathering research material will be the main Hawkins 2 jobs of that person and will take a very long time to accomplish. For a person who is just starting out as an ecologist, manual dexterity is just as important as patience. However, later on in a career as an ecologist, many traits will have to surface . Some of these traits include a sense of professionalism, enthusiasm for the work at hand, deep concern for the world, curiosity and dedication. However, skills that are common to most of the ecologists in the world today are creativity and problem solving which are just as important and probably even more important than the rest. A deep love for the environment around a person is one of the best and most desirable characteristics that a person who wants a job as an ecologist could have. Pre-training occurs when a person volunteers their services to any organization so that they can get the much needed information that they need to perform their job more efficiently. This information would include how to conduct research, how to track animals, and how to clean up disasters in new ways. Getting to see what the animals and nature that a person will most likely be working with or around or would be like is also one of the job details that they must become fluent in. Many organizations, from scouts to the World Wildlife Foundation, can use the services of a ready and able bodied and able minded people to help them out in their conduction of research and concluding hypothesis. Through these organizations a person can make valuable contacts that can help that person get a job in the environmental field or to get a promotion later on in their career. Because of the changes in the world around us, a person in the field of ecology must stay focused on all of the upcoming and new technologies in the world today. A person needs to have a formal education of at least a bachelor's degree. A person will also need at least some experience in conducting research so they will be able to take advantage of certain opportunities in the future. While a person is still living at home, they can find new and inventive ways to Hawkins 3 apply their knowledge of the environmental sciences. Planting and raising a garden, designing a garbage disposable system that will gather the different recyclables are some of the things a person can do. A person can leave high school at the age of sixteen and get a job in some practical part of ecology such as a green house attendant or a tour guild at a local natural reserve. However, if a person further educates themselves they will have a better chance of getting a job that they would want much more. These are all reasons why Fanning says, "While still in high school take a well rounded program including biology, mathematics, physics, geology, chemistry, social sciences and humanities"(30). A college education is mandatory, with an emphasis on biology. Yet that person should also round out their education with all of the other science classes that they can take. Also, taking social sciences and many mathematics classes will round out their schedule. To become an ecologist it is mandatory to have at least a bachelor's degree in an environmental scientist. However, if that person gets a master's or even a doctorate's degree, he or she will be hired before a person with only the bachelor's degree. While combining the pre-training and a college education a person will be building a solid basis for their future career. Ecologists mainly focus their attention on the ecosystems of the world and the impacts that man has on the environment and energy developments on the environment. They also try to understand the links between organisms and their environments. It is just like what the Encyclopedia of Vocational Guidance says about ecologists, "...a primary concern of ecologists today is to study and attempt to find solutions for disruption in various ecosystems. Increasingly, an area of expertise is the reconstruction of ecosystems"(687). Many of the duties which a person in the field of ecology has are of so much importance that many things in this world could not be done without them. Most of the working conditions for a person who goes into Hawkins 4 the field of ecology will mainly be in the outdoor with Mother Nature. Peter Newman once said that, ". . .you will be pioneering what has become on of the most dynamic of the new career opportunities today"(18). Many of the state and federal agencies hire technicians to gather data from backwoods city landfills or even lake and ocean bottoms. As an entry-level ecologist a person will usually be concentrating on hands on work, going out and cleaning up and caring for an area. However, through the seasons an entry-level ecologist may be forced to transfer frequently. After many years as an ecologist working outdoors, he or she may be stuck behind a desk for some time. Over a couple of years as an ecologist a person will possibly be responsible for taking care of an entire woodland. Some of the main job duties of an ecologist are the ability to care for and raise an animal, tag animals, and collect research materials. There are many different jobs available for an ecologist. Some of these jobs are in the private, federal, and public sectors. Because salaries range from state to state and sector to sector it is hard to get an exact amount per year. A salary for a person working for the federal government is dependent on a person's GS level. A GS-5 level person is what a person will probably start at, which is a person with at least a bachelor's degree in biology or a related subject. A GS-5 person salary ranges from $16,973-$22,067. However a person with the highest level GS was last paid $97,317. The federal government's pay scale is slightly better than that of many of the states yet lower than that in the private sector. In the state sector the starting pay in about $12,000 up to $34,000 and usually end up with a job paying about $60,000. All of this information came from the following three books: Careers for Nature Lovers and Other Outdoor Types, Opportunities in Environmental Careers, and The Encyclopedia of Careers and Vocational Guidance.

Bacterial Growth

The Effects of Antibiotics on Bacterial Growth Bacteria are the most common and ancient microorganisms on earth. Most bacteria are microscopic, measuring 1 micron in length. However, colonies of bacteria grown in a laboratory petri dish can be seen with the unaided eye. There are many divisions and classifications of bacteria that assist in identifying them. The first two types of bacteria are archaebacteria and eubacteria. Both groups have common ancestors dating to more than 3 billion years ago. Archaebacteria live in environments where, because of the high temperature, no other life can grow. These environments include hot springs and areas of volcanic activity. They contain lipids but lack certain chemicals in their cell wall. Eubacteria are all other bacteria. Most of them are phototrophic, i.e. they use the sun's energy as food through the process of photosynthesis. Another classification of bacteria is according to their need of oxygen to live. Those who do require oxygen to live are considered aerobes. The bacteria who don't use oxygen to live are known as anaerobes. The shape of specific bacteria provides for the next step in the identification process. Spherical bacteria are called cocci; the bacteria that have a rodlike shape are known as bacilli; corkscrew shaped bacteria are spirilla; and filamentous is the term for bacteria with a threadlike appearance. Hans Christian Joachim Gram, a Danish microbiologist, developed a method for distinguishing bacteria by their different reaction to a stain. The process of applying Gram's stain is as follows: the bacteria are stained with a violet dye and treated with Gram's solution (1 part iodine, 2 parts potassium iodide, and 300 parts water). Ethyl alcohol is then applied to the medium; the bacteria will either preserve the blue color of the original dye or they will obtain a red hue. The blue colored bacteria are gram-positive; the red bacteria are identified as gram-negative. Bacteria contain DNA (deoxyribonucleic acid) just like all cells. However, in bacteria the DNA is arranged in a circular fashion rather than in strands. Bacteria also contain ribosomes which, like in eukaryotic cells, provide for protein synthesis. In order for a bacterium to attach itself to a surface, it requires the aid of pili, or hairlike growths. Bacteria, just like sperm cells, have flagella which assist in movement. But, sperm cells only have one flagellum, whereas bacteria contain flagella at several locations throughout their body surface. Although most bacteria are not harmful, a small fraction of them are responsible for many diseases. These bacterial pathogens have affected humans throughout history. The "plague", an infamous disease caused by bacteria, has killed millions of people. Also, such a disease as tuberculosis, a disease responsible for the lives of many, is caused by bacterial pathogens ingested into the body. Bacteria affect everyone in their daily life because they are found nearly everywhere. They are found in the air, in food, in living things, in non-living things, and on every imaginable surface. Escherichia coli is a disease causing gram-negative bacillus. These bacteria are commonly found within the intestines of humans as well as other vertebrates. This widely spread bacteria is known to cause urinary tract infections as well as diarrhea. Microcococcus Luteus are gram-positive parasitic spherical bacteria which usually grows in grapelike clusters. This species is commonly found in milk and dairy products as well as on dust particles. Bacillus Cereus are a spore forming type of bacteria. They are gram-positive and contain rods. Due to the fact that this bacteria is known to survive cooking, it is a common cause of food poisoning and diarrhea. Seratia Marscens a usually anaerobic bacteria which contains gram-negative rods. This bacteria feeds on decaying plant and animal material. S. marscens are found in water, soil, milk, foods, and certain insects. In spite of the fact that bacteria are harmful to the body, certain measures can be taken in order to inhibit their growth and reproduction. The most common form of bacteria fighting medicines are antibiotics. Antibiotics carry out the action which their Greek origin suggests: anti meaning against, and bios meaning life. In the early parts of the 20th century, a German chemist, Paul Ehrlich began experimentation using organic compounds to combat harmful organisms without causing damage to the host. The results of his experimentation began the study and use of antibiotics to fight bacteria. Antibiotics are classified in various ways. They can be arranged according to the specific action it has on the cell. For example, certain antibiotics attack the cell wall, others concentrate on the cell membrane, but most obstruct protein synthesis. Another form of indexing antibiotics is by their actual chemical structure. Practically all antibiotics deal with the obstruction of synthesis of the cell wall, proteins, or nucleic acids. Some antibacterials interfere with the messenger RNA, consequently mixing up the bacterial genetic code. Penicillins act by inhibiting the formation of a cell wall. This antibiotic works most effectively against gram-positive streptococci, staphylococci (e.g. Micrococcus Luteus) as well as certain gram-negative bacteria. Penicillin is usually prescribed to treat syphilis, gonorrhea, meningitis, and anthrax. Tetracycline inhibits protein synthesis in pathogenic organism. This antibiotic is obtained from the culture of Streptomyces. Streptomycin an antibiotic agent which is obtained from Streptomyces griseus. This antibiotic acts by limiting normal protein synthesis. Streptomycin is effective against E. Coli, gram-negative bacilli, as well as many cocci. Neomycin an antibiotic derived from a strain of Streptomyces fradiae. Neomycin effectively destroys a wide range of bacteria. Kanamycin an antibiotic substance derived from Streptomyces kanamycetius. Its antibacterial action is very similar to that of neomycin. Kanamycin works against many aerobic gram-positive and gram-negative bacteria, especially E. coli. Protracted use may result in auditory as well as other damages. Erythromycin is an antibiotic produced by a strain of Streptomyces erythreaus. This antibiotic works by inhibiting protein synthesis but not nucleic synthesis. Erythromycin has inhibitory effects on gram-negative cocci as well as some gram-positive bacteria. Chloramphenicol is a clinically useful antibiotic in combating serious infections caused by certain bacteria in place of potentially hazardous means of solving the problem. In lab tests, it has been shown that this medicine stopped bacterial reproduction in a wide range of both gram-positive and gram-negative bacteria. The inhibition of cell reproduction caused by Chloramphenicol takes place through interference with protein synthesis. An experiment was conducted in order to determine which antibiotics are most effective in inhibiting bacterial growth. First, the different bacteria were placed on agar inside petri dishes. Then, antibiotic discs were placed into the dishes. Each bacteria was exposed to every one of the antibiotics listed above. The bacteria used in the experiment were: Bacillus Cerus, Escerichia Coli, Seratia Marscens, and Micrococcus Luteus. After a 24 hour incubation period, the results were measured. In order to determine which antibiotic had the most effect their zones of inhibition were recorded. The zone of inhibition refers to the distance from the disc to the outermost section around the disc where no bacterial growth was present. The results can be seen on the graph and data chart. The following is a table showing the different zones of inhibition of each antibiotic in the bacteria culture: Tetracycline Chloramphenicol Kanamycin Neomycin Penicillin Streptomycin Erythromycin B. Cerus 5.5 9 5 6.6 1 7 13 E. Coli 7 4.2 5.5 4.5 no effect 4.6 no effect S. Marscens no effect no effect 4.5 4 no effect 3 no effect M. Luteus 23 22 10 11 23.5 11.5 19 After analysis of the data obtained it is obvious that each antibiotic had a distinct effect on the growth of the different bacteria. The results of this experiment are very important, since they teach of how each bacteria reacts to different antibiotics. This is very valuable because it is the information which assists physicians in prescribing certain medications to cure diseases caused by bacteria.

Bacteria

Antibiotic Resistance in Bacteria For about 50 years, antibiotics have been the answer to many bacterial infections. Antibiotics are chemical substances that are secreted by living things. Doctors prescribed these medicines to cure many diseases. During World War II, it treated one of the biggest killers during wartime - infected wounds. It was the beginning of the antibiotic era. But just when antibiotics were being mass produced, bacteria started to evolve and became resistant to these medicines. Antibiotic resistance can be the result of different things. One cause of resistance could be drug abuse. There are people who believe that when they get sick, antibiotics are the answer. The more times you use a drug, the more it will decrease the effect it has on you. That is because the bacteria has found a way to avoid the effects of that antibiotic. Another cause of resistance is the improper use of drugs. When patients feel that the symptoms of their disease have improved, they often stop taking the drug. Just because the symptoms have disappeared it does not mean the disease has gone away. Prescribed drugs should be taken until all the medicine is gone so the disease is completely finished. If it is not, then this will just give the bacteria some time to find a way to avoid the effects of the drug. One antibiotic that will always have a long lasting effect in history is penicillin. This was the first antibiotic ever to be discovered. Alexander Fleming was the person responsible for the discovery in 1928. In his laboratory, he noticed that in some of his bacteria colonies, that he was growing, were some clear spots. He realized that something had killed the bacteria in these clear spots, which ended up to be a fungus growth. He then discovered that inside this mold was a substance that killed bacteria. It was the antibiotic, penicillin. Penicillin became the most powerful germ-killer known at that time. Antibiotics kill disease-causing bacteria by interfering with their processes. Penicillin kills bacteria by attaching to their cell walls. Then it destroys part of the wall. The cell wall breaks apart and bacteria dies. After four years, when drug companies started to mass produce penicillin, in 1943, the first signs of penicillin-resistant bacteria started to show up. The first bacteria that fought penicillin was called Staphylococcus aureus. This bug is usually harmless but can cause an illness such as pneumonia. In 1967, another penicillin-resistant bacteria formed. It was called pneumococcus and it broke out in a small village in Papua New Guinea. Other penicillin resistant bacteria that formed are Enterococcus faecium and a new strain of gonorrhea. Antibiotic resistance can occur by a mutation of DNA in bacteria or DNA acquired from another bacteria that is drug-resistant through transformation. Penicillin-resistant bacteria can alter their cell walls so penicillin can not attach to it. The bacteria can also produce different enzymes that can take apart the antibiotic. Since antibiotics became so prosperous, all other strategies to fight bacterial diseases were put aside. Now since the effects of antibiotics are decreasing and antibiotic resistance is increasing, new research on how to battle bacteria is starting. Antibiotic resistance spreads fast but efforts are being made to slow it. Improving infection control, discovering new antibiotics, and taking drugs more appropriately are ways to prevent resistant bacteria from spreading. In developing nations, approaches are being made to control infections such as hand washing by health care people, and identifying drug resistant infections quickly to keep them away from others. The World Health Organization has began a global computer program that reports any outbreaks of drug-resistant bacterial infections. In the early 1900's, the discovery of penicillin began the antibiotic era. People thought they have finally won the battle with bacteria. But now since antibiotic resistance is increasing rapidly, new strategies must be developed to destroy these microbes. To many scientists the antibiotic era is over.