Louis Pasteur(1822-1895)-The scientist I adore most!!!

LOUIS PASTEUR(1822-1895)

Louis Pasteur (December 27 1822 – September 28, 1895) was a French chemist and microbiologist best known for his remarkable breakthroughs in the causes and prevention of disease. His experiments supported the germ theory of disease, also reducing mortality from puerperal fever (childbed), and he created the first vaccine for rabies. He was best known to the general public for inventing a method to stop milk and wine from causing sickness - this process came to be called pasteurization. He is regarded as one of the three main founders of microbiology, together with Ferdinand Cohn and Robert Koch. He also made many discoveries in the field of chemistry, most notably the asymmetry of crystals.[1] He is buried beneath the Institut Pasteur, an incredibly rare honor in France, where being buried in a cemetery is mandatory save for the fewer than 300 "Great Men" who are entombed in the Panthéon.

Pasteur's achievements seem wildly diverse at first glance, but a more in-depth look at the evolution of his career indicates that there is a logical order to his discoveries. He is revered for possessing the most important qualities of a scientist: the ability to survey all the known data and link the data for all possible hypotheses, the patience and drive to conduct experiments under strictly controlled conditions, and the brilliance to uncover the road to the solution from the results.
On the discipline of rigid and strict experimental tests he commented, "Imagination should give wings to our thoughts but we always need decisive experimental proof, and when the moment comes to draw conclusions and to interpret the gathered observations, imagination must be checked and documented by the factual results of the experiment."


In 1854 Pasteur was appointed professor of chemistry at the University of Lille. Part of the remit of the faculty of sciences was to find solutions to the practical problems of local industries, particularly the manufacture of alcoholic drinks. He was able to demonstrate that organisms such as bacteria were responsible for souring wine and beer (he later extended his studies to prove that milk was the same), and that the bacteria could be removed by boiling and then cooling the liquid. This process is now called pasteurisation.


Louis Pasteur - experimented on animals to prove theory thatgermscause disease and developed an anthrax vaccine

Pasteur then undertook experiments to find where these bacteria came from, and was able to prove that they were introduced from the environment. This was disputed by scientists who believed they could spontaneously generate. In 1864, the French Academy of Sciences accepted Pasteur's results. By 1865, Pasteur was director of scientific studies at the École Normale, where he had studied. He was asked to help the silk industry in southern France, where there was an epidemic amongst the silkworms. With no experience of the subject, Pasteur identified parasitic infections as the cause and advocated that only disease-free eggs should be selected. The industry was saved.
Pasteur's various investigations convinced him of the rightness of the germ theory of disease, which holds that germs attack the body from outside. Many felt that such tiny organisms as germs could not possibly kill larger ones such as humans. Pasteur now extended this theory to explain the causes of many diseases - including anthrax, cholera, TB and smallpox - and their prevention by vaccination. He is best known for his work on the development of vaccines for rabies.
In 1888, a special institute was founded in Paris for the treatment of diseases. It became known as the Institut Pasteur. Pasteur was its director until his death on 28 September 1895. He was a national hero and was given a state funeral.
references:
www.britannica.com/eb/article-9108485/Louis-Pasteur - 60k
www.bbc.co.uk/history/historic_figures/pasteur_louis.shtml

what is biotechnology???

(Pamela Peters, from Biotechnology: A Guide To Genetic Engineering. Wm. C. Brown Publishers, Inc., 1993. )
Biotechnology in one form or another has flourished since prehistoric times. When the first human beings realized that they could plant their own crops and breed their own animals, they learned to use biotechnology. The discovery that fruit juices fermented into wine, or that milk could be converted into cheese or yogurt, or that beer could be made by fermenting solutions of malt and hops began the study of biotechnology. When the first bakers found that they could make a soft, spongy bread rather than a firm, thin cracker, they were acting as fledgling biotechnologists. The first animal breeders, realizing that different physical traits could be either magnified or lost by mating appropriate pairs of animals, engaged in the manipulations of biotechnology.
What then is biotechnology? The term brings to mind many different things. Some think of developing new types of animals. Others dream of almost unlimited sources of human therapeutic drugs. Still others envision the possibility of growing crops that are more nutritious and naturally pest-resistant to feed a rapidly growing world population. This question elicits almost as many first-thought responses as there are people to whom the question can be posed.
In its purest form, the term "biotechnology" refers to the use of living organisms or their products to modify human health and the human environment. Prehistoric biotechnologists did this as they used yeast cells to raise bread dough and to ferment alcoholic beverages, and bacterial cells to make cheeses and yogurts and as they bred their strong, productive animals to make even stronger and more productive offspring.
Throughout human history, we have learned a great deal about the different organisms that our ancestors used so effectively. The marked increase in our understanding of these organisms and their cell products gains us the ability to control the many functions of various cells and organisms. Using the techniques of gene splicing and recombinant DNA technology, we can now actually combine the genetic elements of two or more living cells. Functioning lengths of DNA can be taken from one organism and placed into the cells of another organism. As a result, for example, we can cause bacterial cells to produce human molecules. Cows can produce more milk for the same amount of feed. And we can synthesize therapeutic molecules that have never before existed...

plant tissue culture

What is Plant Tissue Culture?

Plant cells can be grown in isolation from intact plants in tissue culture systems. The cells have the characteristics of callus cells, rather than other plant cell types. These are the cells that appear on cut surfaces when a plant is wounded and which gradually cover and seal the damaged area.
Pieces of plant tissue will slowly divide and grow into a colourless mass of cells if they are kept in special conditions. These are:
initiated from the most appropriate plant tissue for the particular plant variety
presence of a high concentration of auxin and cytokinin growth regulators in the growth media
a growth medium containing organic and inorganic compounds to sustain the cells
aseptic conditions during culture to exclude competition from microorganisms
The plant cells can grow on a solid surface as friable, pale-brown lumps (called callus), or as individual or small clusters of cells in a liquid medium called a suspension culture. These cells can be maintained indefinitely provided they are sub-cultured regularly into fresh growth medium.
Tissue culture cells generally lack the distinctive features of most plant cells. They have a small vacuole, lack chloroplasts and photosynthetic pathways and the structural or chemical features that distinguish so many cell types within the intact plant are absent. They are most similar to the undifferentiated cells found in meristematic regions which become fated to develop into each cell type as the plant grows. Tissue cultured cells can also be induced to re-differentiate into whole plants by alterations to the growth media.
Plant tissue cultures can be initiated from almost any part of a plant. The physiological state of the plant does have an influence on its response to attempts to initiate tissue culture. The parent plant must be healthy and free from obvious signs of disease or decay. The source, termed explant, may be dictated by the reason for carrying out the tissue culture. Younger tissue contains a higher proportion of actively dividing cells and is more responsive to a callus initiation programme. The plants themselves must be actively growing, and not about to enter a period of dormancy.
The exact conditions required to initiate and sustain plant cells in culture, or to regenerate intact plants from cultured cells, are different for each plant species. Each variety of a species will often have a particular set of cultural requirements. Despite all the knowledge that has been obtained about plant tissue culture during the twentieth century, these conditions have to be identified for each variety through experimentation.

Demonstration of tissue culture for teaching

IntroductionThe starting point for all tissue cultures is plant tissue, called an explant. It can be initiated from any part of a plant - root, stem, petiole, leaf or flower - although the success of any one of these varies between species. It is essential that the surface of the explant is sterilised to remove all microbial contamination. Plant cell division is slow compared to the growth of bacteria and fungi, and even minor contaminants will easily over-grow the plant tissue culture. The explant is then incubated on a sterile nutrient medium to initiate the tissue culture. The composition of the growth medium is designed to both sustain the plant cells, encourage cell division, and control development of either an undifferentiated cell mass, or particular plant organs.
The concentration of the growth regulators in the medium, namely auxin and cytokinin, seems to be the critical factor for determining whether a tissue culture is initiated, and how it subsequently develops. The explant should initially form a callus, from which it is possible to generate multiple embryos and then shoots, forming the basis for plant regeneration and thus the technology of micropropagation. The first stage of tissue culture initiation is vital for information on what combination of media components will give a friable, fast-growing callus, or a green chlorophyllous callus, or embryo, root or shoot formation.
There is at present no way to predict the exact growth medium, and growth protocol, to generate a particular type of callus. These characteristics have to be determined through a carefully designed and observed experiment for each new plant species, and frequently also for each new variety of the species which is taken into tissue culture. The basis of the experiment will be media and protocols that give the desired effect in other plant species, and experience.
The demonstrationThe strategy for designing a medium to initiate tissue culture, showing how growth regulators and other factors modulate development, can be demonstrated using the African Violet, a popular house plant. Leaf sections are the source of explants. This demonstration is regularly carried out by a student class, and gives reliable results. Sterile supplies are provided from central facilities, and provision of sterile working areas (for example, in laminar flow hoods) is an advantage, although cultures can be initiated in an open laboratory with careful aseptic technique. The standard precautions used during any laboratory work involving chemicals or microbes should be adopted. If you are in any doubt about safety hazards associated with this demonstration, you should consult your local safety adviser.
Step 1 - selection of the leavesLeaves are cut from healthy plants, leaving a short length of petiole attached. They should be selected to each yield several explants of leaf squares with approximately 1 cm sides. The youngest and oldest leaves should be avoided.
Wash the dust off the leaves in a beaker of distilled water, holding the leaf stalk with forceps.
Step 2 - surface sterilisation and preparation of the explantsThis part of the procedure should be carried out in a sterile working area, or with meticulous aseptic technique.
The leaf, with the petiole still attached, should be immersed in 70% ethanol for 30 seconds, then transferred to a sterile petri dish. Sterile scissors and forceps are then used to cut squares from the leaf as explants, each with approximately 1 cm sides.
The explants are transferred into a 10% hypochlorite bleach solution for 5 minutes, gently agitating once or twice during this time. They are then washed free of bleach by immersing in four successive beakers of sterile distilled water, leaving them for 2-3 minutes in each.
Three explants are placed on each petri dish of growth medium (see table and below), with the upper epidermis pressed gently against the surface of the agar to make good contact.
The petri dishes are sealed with plastic film to prevent moisture loss, and incubated at 25oC in 16h light/8h dark.
Step 3 - assessment of tissue culture developmentThe explants are incubated for 4 - 6 weeks, and inspected at weekly or fortnightly intervals. The growth of obvious bacterial or fungal colonies indicates contamination, and data from such cultures is obviously suspect. The development of dark brown tissue cultures can also be a consequence of contamination.
The media used in the demonstration are designed to show the effects of auxin, cytokinin, sucrose and mineral salts on development. The media were based on the well-known Murashige and Skoog inorganic medium, with additions as shown in this table.
Typical results
After about 8 weeks on each medium they show the results. To summarise, multiple adventitious buds form on the control medium, leading to many small shoots on the upper surface where the leaf is not in contact with the medium.
Absence of sucrose inhibits this production. Shoot production is also limited on the low sucrose concentration, but comparable with the control at high sucrose.
At zero and low levels of cytokinin, callus forms where the leaf surface is in contact with the medium, while at high levels, shoot formation is stimulated.
At zero and low levels of auxins there is a stimulus to shoot formation, but at high concentrations, large numbers of roots are formed.
At low and zero levels of MS salts, there is no growth at all.
These very obvious variations demonstrate the importance of a carbon and inorganic salt source for plant growth, as well as the effect of the auxin:cytokinin ratio on the control of plant development....

For publications describing this work, follow this link...

Stem Cells for the Future Treatment

Parkinson's disease (PD) is a very common neurodegenerative disorder that affects more than 2% of the population over 65 years of age. PD is caused by a progressive degeneration and loss of dopamine (DA)-producing neurons, which leads to tremor, rigidity, and hypokinesia (abnormally decreased mobility). It is thought that PD may be the first disease to be amenable to treatment using stem cell transplantation. Factors that support this notion include the knowledge of the specific cell type (DA neurons) needed to relieve the symptoms of the disease. In addition, several laboratories have been successful in developing methods to induce embryonic stem cells to differentiate into cells with many of the functions of DA neurons.
In a recent study, scientists directed mouse embryonic stem cells to differentiate into DA neurons by introducing the gene Nurr1. When transplanted into the brains of a rat model of PD, these stem cell-derived DA neurons reinnervated the brains of the rat Parkinson model, released dopamine and improved motor function.
Regarding human stem cell therapy, scientists are developing a number of strategies for producing dopamine neurons from human stem cells in the laboratory for transplantation into humans with Parkinson's disease. The successful generation of an unlimited supply of dopamine neurons could make neurotransplantation widely available for Parkinson's patients at some point in the future...

STEM CELLS: a new promise of biotechnology researches

Stem cells have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
I. Introduction
Research on stem cells is advancing knowledge about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. This promising area of science is also leading scientists to investigate the possibility of cell-based therapies to treat disease, which is often referred to as regenerative or reparative medicine.
Stem cells are one of the most fascinating areas of biology today. But like many expanding fields of scientific inquiry, research on stem cells raises scientific questions as rapidly as it generates new discoveries.
The NIH developed this primer to help readers understand the answers to questions such as: What are stem cells? What different types of stem cells are there and where do they come from? What is the potential for new medical treatments using stem cells? What research is needed to make such treatments a reality?
What are stem cells and why are they important?
Stem cells have two important characteristics that distinguish them from other types of cells. First, they are unspecialized cells that renew themselves for long periods through cell division. The second is that under certain physiologic or experimental conditions, they can be induced to become cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas.
Scientists primarily work with two kinds of stem cells from animals and humans: embryonic stem cells and adult stem cells, which have different functions and characteristics that will be explained in this document. Scientists discovered ways to obtain or derive stem cells from early mouse embryos more than 20 years ago. Many years of detailed study of the biology of mouse stem cells led to the discovery, in 1998, of how to isolate stem cells from human embryos and grow the cells in the laboratory. These are called human embryonic stem cells. The embryos used in these studies were created for infertility purposes through in vitro fertilization procedures and when they were no longer needed for that purpose, they were donated for research with the informed consent of the donor.
Stem cells are important for living organisms for many reasons. In the 3- to 5-day-old embryo, called a blastocyst, stem cells in developing tissues give rise to the multiple specialized cell types that make up the heart, lung, skin, and other tissues. In some adult tissues, such as bone marrow, muscle, and brain, discrete populations of adult stem cells generate replacements for cells that are lost through normal wear and tear, injury, or disease.
It has been hypothesized by scientists that stem cells may, at some point in the future, become the basis for treating diseases such as Parkinson's disease, diabetes, and heart disease.
Scientists want to study stem cells in the laboratory so they can learn about their essential properties and what makes them different from specialized cell types. As scientists learn more about stem cells, it may become possible to use the cells not just in cell-based therapies, but also for screening new drugs and toxins and understanding birth defects. However, as mentioned above, human embryonic stem cells have only been studied since 1998. Therefore, in order to develop such treatments scientists are intensively studying the fundamental properties of stem cells, which include:
determining precisely how stem cells remain unspecialized and self renewing for many years; and
identifying the signals that cause stem cells to become specialized cells.

Where did biotechnology begin??

With the Basics
Certain practices that we would now classify as applications of biotechnology have been in use since man's earliest days. Nearly 10,000 years ago, our ancestors were producing wine, beer, and bread by using fermentation, a natural process in which the biological activity of one-celled organisms plays a critical role.
In fermentation, microorganisms such as bacteria, yeasts, and molds are mixed with ingredients that provide them with food. As they digest this food, the organisms produce two critical by-products, carbon dioxide gas and alcohol.
In beer making, yeast cells break down starch and sugar (present in cereal grains) to form alcohol; the froth, or head, of the beer results from the carbon dioxide gas that the cells produce. In simple terms, the living cells rearrange chemical elements to form new products that they need to live and reproduce. By happy coincidence, in the process of doing so they help make a popular beverage.
Bread baking is also dependent on the action of yeast cells. The bread dough contains nutrients that these cells digest for their own sustenance. The digestion process generates alcohol (which contributes to that wonderful aroma of baking bread) and carbon dioxide gas (which makes the dough rise and forms the honeycomb texture of the baked loaf).
Discovery of the fermentation process allowed early peoples to produce foods by allowing live organisms to act on other ingredients. But our ancestors also found that, by manipulating the conditions under which the fermentation took place, they could improve both the quality and the yield of the ingredients themselves.
Crop Improvement
Although plant science is a relatively modern discipline, its fundamental techniques have been applied throughout human history. When early man went through the crucial transition from nomadic hunter to settled farmer, cultivated crops became vital for survival. These primitive farmers, although ignorant of the natural principles at work, found that they could increase the yield and improve the taste of crops by selecting seeds from particularly desirable plants.
Farmers long ago noted that they could improve each succeeding year's harvest by using seed from only the best plants of the current crop. Plants that, for example, gave the highest yield, stayed the healthiest during periods of drought or disease, or were easiest to harvest tended to produce future generations with these same characteristics. Through several years of careful seed selection, farmers could maintain and strengthen such desirable traits.
The possibilities for improving plants expanded as a result of Gregor Mendel's investigations in the mid-1860s of hereditary traits in peas. Once the genetic basis of heredity was understood, the benefits of cross-breeding, or hybridization, became apparent: plants with different desirable traits could be used to cultivate a later generation that combined these characteristics.
An understanding of the scientific principles behind fermentation and crop improvement practices has come only in the last hundred years. But the early, crude techniques, even without the benefit of sophisticated laboratories and automated equipment, were a true practice of biotechnology guiding natural processes to improve man's physical and economic well-being.
Harnessing Microbes for Health
Every student of chemistry knows the shape of a Buchner funnel, but they may be unaware that the distinguished German scientist it was named after made the vital discovery (in 1897) that enzymes extracted from yeast are effective in converting sugar into alcohol. Major outbreaks of disease in overcrowded industrial cities led eventually to the introduction, in the early years of the present century, of large-scale sewage purification systems based on microbial activity. By this time it had proved possible to generate certain key industrial chemicals (glycerol, acetone, and butanol) using bacteria.
Another major beneficial legacy of early 20th century biotechnology was the discovery by Alexander Fleming (in 1928) of penicillin, an antibiotic derived from the mold Penicillium. Large-scale production of penicillin was achieved in the 1940s. However, the revolution in understanding the chemical basis of cell function that stemmed from the post-war emergence of molecular biology was still to come. It was this exciting phase of bioscience that led to the recent explosive development of biotechnology.