WHERE IS GOLD FOUND?

Rocks: Gold is present in tiny quantities in all igneous rocks. Some patches of rocks contain a high enough concentration of gold to make it worthwhile for companies to mine, crush, and chemically leach the metal from the ore. High -quality ore contains only about 30 grams of gold per ton of rock.

Reefs: On rare occasions gold is found in sheets or veins wedged between layers of quartz. This is known as reef gold.

Rivers: Over time, gold - bearing reefs that become exposed to sun, rain, and wind break down, releasing trapped gold, which then accumulates in creeks and rivers as tiny speaks, or flakes. In this form it is known as alluvial gold.

Earth's Surface: Odd -shaped clumps of gold that seem to form at random in the earth's surface are known as nuggets. These clumps can sometimes reach spectacular sizes. The largest gold nugget ever found in Australia was called The Welcome Stranger, and it weighed about 70 kilograms! It was discovered in 1869 in the Australia state of Victoria. Australia is the home of big nuggets, having yielded 23 of the 25 biggest nuggets ever discovered. Today gold nuggets, which can be as small as a match head, are more rare than gem -quality diamonds.

Collected from "Awake, September 22, 2005"

Dactylorhiza

Dactylorhiza is a genus of terresterial (ground-dwelling) plants from the orchid family (Orchidaceae). The name Dactylorhiza is derived from Greek words daktylos" (finger) and "rhiza" (root). This is because of the shape of the genus' two underground tubers. Dactylorhiza were previously classified under Orchis.

These orchids are distributed throughout the subarctic and temperate northern hemisphere : in Europe, from Scandinavia to North Africa; also on Madeira, Iceland, West Asia, North Asia, the Humalayas, North America and even in Alask.

These terrestrial orchids grow in basic soils in wet meadows, bogs, heathland and in areas sparsely populated by trees. They are tuberous geophytes. In a thickened underground stem, they can store a large amount of water to survive arid conditions.

The long leaves are lanceolate and, in most species, also speckled. They grow along a rather long stem which reaches a height of 70-90 cm. Leaves higher on the stem are shorter than leaves lower on the stem.The inflorescence, compared to the length of the plant, is rather short. It consists of a compact raceme with 25-50 flowers. These develop from axillary buds. The dominant colors are all shades of pink to red, sprinkled with darker speckles.

UTILITY OF RANDOM AMPLIFICATION OF POLYMORPHIC DNA -POLYMERASE CHAIN REACTION (RAPD-PCR) IN BIOLOGICAL SCIENCES

Seminar Presentation Abstract

Mahendra Chaudhary

22nd Dec ,2006

This presentation focuses on random amplification of polymorphic DNA (RAPD)-polymerase chain reaction (PCR) technique and its utility in biological research .PCR, an in vitro replication of DNA, is used to amplify specific DNA fragments by a repeating cycle of denaturation, annealing and extension in an automated thermal cycler [1]. RAPD-PCR, a variation of general PCR where forward and reverse primers are used to amplify specific DNA segment, is used to amplify an unknown segment of DNA flanked by a single arbitrary primer [2] that is able to anneal and prime at multiple locations throughout the genome. Thus, a spectrum of amplified products is obtained on agarose gel electrophoresis characteristic to the chromosome of the organism. RAPD-PCR can be used to develop genome fingerprinting and, thus, high- resolution genetic maps for those organisms whose genetic markers are not known [3]. Hence, the technique can be used in forensic analysis. A series of RAPD primers can be used to develop RAPD markers useful to further categorize a given species. RAPD -PCR has been successfully used to detect genetic variation among Bacillus thuriengiensis serovars [4] and has been used to assay genetic diseases[5].

References:
1. Padmalatha k and Prasad MNV, (2006).Optimization of DNA isolation and PCR protocol for RAPD analysis of selected medicinal and aromatic plants of conservation concern from Peninsular India. African Journal of Biotechnology, 5(3), 230-234.

2. Singh BD, (1998). Recombinant DNA Technology In: Biotechnology, Kalyani Publishers, 28-36.

3. Mitchelson KR, Drenth J, Doung H, et al, (1999). Direct Sequencing of RAPD fragments Using 3' - extended oligonucleotide primers dye terminator cycle -sequencing. Nucleic Acid Research, 27(19), e28.

4. Adelaida M, Gaviri R and Priest FG, (2003). Molecular Typing of Bacillus thuringiensis Serovars by RAPD-PCR. System. Appl. Microbiol. 26, 254-261.

5. Olivier M, Meehi MA, and Lust G, (1999). RAPD Sequences as Markers for CanineGenetic Studies. The Amecian Genetic Association, 90, 78-82.