explorer blog

Welcome: April 2007

Friday, April 27, 2007




Soil:



Superficial covering that overlies the bedrock of most of the land area of the Earth; an aggregation of unconsolidated mineral and organic particles produced by physical, chemical, and biological processes; and the medium that supports the growth of most plants. The primary components of soil are inorganic materials that are mostly produced by the weathering of bedrock; soluble nutrients, or chemical elements and compounds used by plants for growth; various forms of organic matter; and gases (notably oxygen, nitrogen, and carbon dioxide) and water required by plants and soil organisms.


Soil is an important natural resource and is the medium within which most agriculture takes place. The specific properties of soil are of great concern to farmers. Knowledge of the mineral and organic components of soils, of the amount of air they contain (aeration), and of their water-holding capacity, as well as of many other aspects of soil structure, is necessary for the successful production of crops. The characteristics required for successful crop growth are not necessarily inherent in the soil itself; some are created by successful soil management. The cultivation of land, however, often depletes soil of essential nutrients, notably nitrogen, potassium, and calcium, and deprives it of its natural vegetational covering, and thus much of its protection against erosion by water and wind. Agriculturalists have had to develop methods both of preventing the harmful alteration of soils that can result from cultivation and of rebuilding soil that has already been detrimentally altered.


Sunday, April 22, 2007




Biotechnology :



The use of living organisms to manufacture pharmaceuticals and other products and to promote industrial processes. Microbes, such as bacteria, and fungi were first harnessed in this way, followed by plants and most recently by animals. “Old” biotechnology includes well-established microbial processes such as brewing, sewage disposal, and the production of antibiotics. However, the term has become particularly familiar since the development of genetic engineering during the 1970s. Much “new” biotechnology uses organisms genetically altered to work more effectively than before, or to function in entirely new ways.

Friday, April 20, 2007




Boxing Day :



popular term applied to December 26 in England, Wales, parts of Canada, and in some other countries of the Commonwealth of Nations. Traditionally, on that day the employers would give presents, generally of money, to servants, tradespeople, and itinerants. These presents came to be known as Christmas boxes. In rural parts of England and Wales, it was traditional for small boys to capture a robin and take it in a box from house to house, asking for alms. Boxing Day is a legal bank holiday.





Aardwolf (Afrikaans, “earth wolf”) :



carnivorous mammal of southern and eastern Africa, closely related to the hyena. The aardwolf stands 45 to 50 cm (18 to 20 in) high at the shoulder, has a body length of 50 to 80 cm (27 to 31 in), and is covered with long, coarse hair and soft underfur. It is light buff in colour, with black bands. At night it leaves its burrow, travelling singly or in a group, to forage for insects, especially termites. When attacked, the aardwolf erects its mane, achieving a formidable appearance, and ejects a foul-smelling fluid from its anal glands. It has weak jaws and small teeth, but is able to use its sharp canine teeth to fight off such enemies as the dog. Towards December, the female aardwolf finds a burrow and bears a litter of one to five young.


Scientific classification:

The aardwolf is classified as Proteles cristatus. It is usually placed in the hyena family, Hyaenidae. Some experts, however, place the aardwolf in a separate family, Protelidae, because of certain anatomical differences between the aardwolf and the hyena. For example, the aardwolf has five toes on its forefeet, whereas the hyena has only four.

Monday, April 02, 2007




Useful Proteins from Bacteria :



A living cell is a protein factory. It synthesizes the enzymes and other proteins that maintain its own integrity and physiological processes, and (in multicelled organisms) it often synthesizes and secretes other proteins that perform some specialized function contributing to the life of the organism as a whole. Different kinds of cells make different proteins, following instructions encoded in the DNA of their genes. Recent advances in molecular biology make it possible to alter those instructions in bacterial cells, thereby designing bacteria that can synthesize nonbacterial proteins. The bacteria are "recombinants." They contain, along with their own genes, part or all of a gene from a human cell or other animal cell. If the inserted gene is one for a protein with an important biomedical application, a culture of the recombinant bacteria, which can be grown easily and at low cost, will serve as an efficient factory for producing that protein.

Many laboratories in universities and in an emerging "applied genetics" industry are working to design bacteria able to synthesize such nonbacterial proteins. A growing tool kit of "genetic engineering" techniques makes it possible to isolate one of the million-odd genes of an animal cell, to fuse that gene with part of a bacterial gene and to insert the combination into bacteria. As those bacteria multiply they make millions of copies of their own genes and of the animal gene inserted among them. If the animal gene is fused to a bacterial gene in such a way that a bacterium can treat the gene as one of its own, the bacteria will produce the protein specified by the animal gene. New ways of rapidly and easily determining the exact sequence of the chemical groups that constitute a molecule of DNA make it possible to learn the detailed structure of such "cloned" genes. After the structure is known it can be manipulated to produce DNA structures that function more efficiently in the bacterial cell.

In this article we shall first describe some of these techniques in a general way and then tell how we and our colleagues Argiris Efstratiadis, Stephanie Broome, Peter Lomedico and Richard Tizard applied them in our laboratory at Harvard University to copy a rat gene that specifies the hormone insulin, to insert the gene into bacteria and to get the bacteria to manufacture a precursor of insulin. In an exciting application of this technology Charles Weissmann and his colleagues at the University of Zurich recently constructed bacteria that produce human interferon, a potentially useful antiviral protein.

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