Genetic variability of Channa punctatus populations using randomly amplified polymorphic DNA

Genetic variations between Channa punctatus populations collected from three rivers of south India were examined using randomly amplified polymorphic DNA (RAPD). Sixty samples from each population were collected. Genomic DNA was isolated from the blood samples. Out of the 20 primers tested, six primers were used for genetic variation studies. A total of 42 RAPD bands were amplified in C. punctatus by the six primers. The total number of bands observed ranged from 34 in the Quilon population to 37 in the Thirunelveli population. Among the three populations, the highest genetic identity (0.9231) was found between Thirunelveli and Quilon populations. The results of the present study demonstrated that Thirunelveli and Quilon populations are more related to each other than to the Coimbatore population.     

A New High-Temperature Superconductor: Bi2Sr3-x Cax Cu2O8+y

A new superconductor that displays onset behavior near 120 K has been identified as Bi(2)Sr(3-x)Ca(x)Cu(2)O(8+y), with x ranging from about 0.4 to 0.9. Single crystal x-ray diffraction data were used to determine a pseudo-tetragonal structure based on an A-centered orthorhombic subcell with a = 5.399 A, b= 5.414A, and c = 30.904 A. The structure contains copper-oxygen sheets as in La(2)CuO(4) and YBa(2)Cu(3)O(7), but the copper-oxygen chains present in YBa(2)Cu(3)O(7) do not occur in Bi(2)Sr(3-x)Ca(x)Cu(2)O(8+y). The structure is made up of alternating double copper-oxygen sheets and double bismuth-oxygen sheets. There are Ca(2+) and Sr(2+) cations between the adjacent Cu-O sheets; Sr(2+) cations are also found between the Cu-O and Bi-O sheets. Electron microscopy studies show an incommensurate superstructure along the a axis that can be approximated by an increase of a factor of 5 over the subcell dimension. This superstructure is also observed by x-ray diffraction on single crystals, but twinning can make it appear that the superstructure is along both a and b axes. Flux exclusion begins in our samples at about 116 K and is very strong by 95 K. Electrical measurements on a single crystal of Bi(2)Sr(3-x)Ca(x)Cu(2)O(8+y) show a resistivity drop at about 116 K and apparent zero resistivity at 91 K.     

Anti-inflammatory and antinociceptive activities of Trewia polycarpa roots

The alcoholic extract of Trewia polycarpa roots, when administered orally to rats at doses of 50-400 mg/kg, exhibited a dose-dependent anti-inflammatory activity in both acute and chronic models. It also showed a significant antinociceptive action mice in the dose range of 25-200 mg/kg. The extract did not reveal any toxicity in rats up to a dose of 3.2 g/kg (p.o.). It showed the presence of terpenoids, alkaloids, flavonoids, quinones and glycosides on phytochemical screening.     

Dynamic heat flux measurement for advanced insulation materials

Odour formation in the textile is a serious and embarrassing problem for an individual. The axilla born bacterial species are noted as the main reason for odour formation in axilla. In this research an attempt has been made to identify the odour generating compounds on the textile material after wear trial using gas chromatography and mass spectrum (GC-MS). The result indicates that the worn textile material consisted steroidal fractions of 5a-androst-16-ene-3-one and cholesterol, the major odour forming source from axilla. The results also identified the other important odour forming fatty acids and alcohols like lauric acids, diethyl esters of 1,2-benzenedicarboxylic acid, methyl esters of tetradecanoic acid, 3- methylhexanoic acid, Tetradecanol and acetic acid in axilla worn textile. These components were the derivatives of axilla specific odourous components like phthalic acid, myristic acid, isobutric acid and alcohols. The effect of Terminalia chebula extract finish on the odour formation also analysed and the results shows a considerable reduction in odour causing short chain volatile fatty acids (VFAs) in the worn textile compare to the untreated textile. The analysis also identified more amounts of active components of Terminalia chebula on the fabric surface instead of the odourous components from axilla.     

Host-delivered RNAi-mediated root-knot nematode resistance in <Emphasis Type="Italic">Arabidopsis</Emphasis> by targeting <Emphasis Type="Italic">splicing factor</Emphasis> and <Emphasis Type="Italic">integrase</Emphasis> genes

Root-knot nematodes (RKNs) are one of the most important biotic factors limiting crop productivity in many crop plants. The major RKN control strategies include development of resistant cultivars, application of nematicides and crop rotation, but each has its own limitations. In recent years, RNA interference (RNAi) has become a powerful approach for developing nematode resistance. The two housekeeping genes, splicing factor and integrase, of Meloidogyne incognita were targeted for engineering nematode resistance using a host-delivered RNAi (HD-RNAi) approach. Splicing factor and integrase genes are essential for nematode development as they are involved in RNA metabolism. Stable homozygous transgenic Arabidopsis lines expressing dsRNA for both genes were generated. In RNAi lines of splicing factor gene, the number of galls, females and egg masses was reduced by 71.4, 74.5 and 86.6%, respectively, as compared with the empty vector controls. Similarly, in RNAi lines of the integrase gene, the number of galls, females and egg masses was reduced up to 59.5, 66.8 and 63.4%, respectively, compared with the empty vector controls. Expression analysis revealed a reduction in mRNA abundance of both targeted genes in female nematodes feeding on transgenic plants expressing dsRNA constructs. The silencing of housekeeping genes in the nematodes through HD-RNAi significantly reduced root-knot nematode infectivity and suggests that they will be useful in developing RKN resistance in crop plants.     

Nerve insensitivity resistance to pyrethroids in Heliothine Lepidoptera

A neurophysiological assay developed previously was used to assess the incidence of nerve insensitivity resistance to synthetic pyrethroids in field strains of Helicoverpa armigera. Almost 70% of individuals from a sample of a highly pyrethroid-resistant population from Jiangsu Province, China were nerve-insensitive. Subsequent selection resulted in a strain homogeneous for expression of this mechanism. Likewise, over 95% of a sample from a strain of the insects from Andhra Pradesh, India were nerve-insensitive and a homogeneous strain was developed. Development of a nerve-insensitive laboratory strain of Heliothis virescens was undertaken but homozygosity could not be obtained. It is suggested that high fitness costs may be associated with this mechanism. The incidence of nerve insensitivity in Heliothine pests is reviewed and the role of phenotypic expression assays in molecular studies highlighted. ©1997 SCI