Transmission Studies with Cucumber Green Mottle Mosaic Virus

Cucumber green mottle mosaic virus may spread in bottlegourd under field conditions through soil contaminated with infected plant debris followed by contact. No seed transmission was noticed in bottlegourd (Lagenaria siceraria) or vegetable marrow (Cucurbita pepo) although pollen grains and cotyledons from infected bottlegourd flowers or seeds, respectively, contained negliginle amounts of virus. Cucumber leaf beerles (Raphidopalpa fevicollis) are probable vectors since their regurgitated fluid and excretes contained infective virus particles. No vector fungi were found in the soil around infected bottlegourd plants.     

An ecological study of three freshwater ponds of hyderabad-India IV. the phytoplankton (diatoms,euglenineae and myxophyceae)

Data on the ecology of Diatoms, Euglenineae and Myxophyceae in three freshwater ponds, differing in chemical composition and algal flora, situated in the vicinity of Hyderabad-India are presented. An attempt has been made to isolate various genera into groups, as their multiplication depended on particular ranges of a single chemical factor or set of factors. Several species could be separated into seasonal forms as they occur in particular periods of the year. Others could be grouped under indifferent forms as these are neither influenced by fluctuations in chemical factors nor by seasonal changes.     

Factor analysis in clusterbean (Cyamopsis tetragonoloba (L.) Taub)

Summary The pattern of diversity in forty genotypes of clusterbean (Cyamopsis tetragonoloba (L.) Taub) was analysed using the centroid method of factor analysis based on nine characters. Three factors were found to adequately account for most of the intercorrelations in the four environments. Branches, clusters, pods and seed yield/plant could be grouped as productivity factors; days to flowering, maturity and plant height as growth factors; seeds/pod and gum content as economic factor. Interestingly, the constitution of the factors were the same in all the environments. The loadings on the economic factors were relatively unstable, whereas the loadings on productivity and growth factors were stable. It is concluded that productivity and growth factors play a pivotal role towards diversity in clusterbean. The results of factor analysis provides confirmatory evidence of diversity in clusterbean, which was earlier studied by using generalized distance, and thus proves the adequacy of the centroid method in biological investigations.     

Biological and cultural determinants of immunoglobulin levels in a Brazilian population with Chagas' disease

Summary Under a general model the genetic heritability is 0.33 for IgA, 0.34 for IgG and 0.12 for IgM, in a Brazilian population with Chagas' disease. Cultural heritability is much smaller. The analyses suggest that, with respect to family resemblance for immunoglobulins, there is no discrepancy between this sample and those from healthy populations reanalyzed recently (Barbosa et al. 1981).This work was supported by Grants 79/0482 FAPESP (Brazil), 77/2222.1392 CNPq (Brazil) and GM 17173 (Hawaii) with collaboration of the Fundação Instituto Osvaldo Cruz (Bambui, MG). Partly supported by NIH Grants GM 24941 and GM 28719.     

Immobilization of hydrogenases for biophotolytic hydrogen production; stability and kinetics

Summary Hydrogenases from Clostridium pasteurianum and Desulfovibrio desulfuricans were immobilized on solid supports with retention of 50% activity. The immobilized enzymes were more stable than the free enzymes and were active in the biophotolytic hydrogen production from water.     

Spectrophotometric assay of immobilized tannase

A procedure for the assay of immobilized tannase with Polyacrylamide gel, collagen and Duolite-S-762 as matrices is described. It is based on the spectrophotometric determination of gallic acid formed by the enzymatic hydrolysis of tannic acid. The kinetic parameters of the enzymatic reaction have been studied and an assay procedure has been formulated. This method appears to be much more accurate than those reported earlier.     

Synthesis of lysine-containing fragments of the Proteus mirabilis O27 O-specific polysaccharide and neoglycoconjugates therefrom.

Amide-linked lysine mono- and di-uronic acid fragments of the O-specific polysaccharide from P. mirabilis O27 have been synthesised. N epsilon-Boc-L-lysine tert-butyl ester was condensed with 2-azidoethyl glycosides of glucuronic acid and beta-D-GlcpNAc-(1----3)-beta-D-GlcpA. Transformation of the products into 2-acrylamidoethyl glycosides, followed by deprotection using trifluoroacetic acid, gave the target monomers that were converted into high-molecular-weight copolymer-type neoglycoconjugates.     

Identification of a new group-specific determinant on hepatitis B surface antigen with a synthetic peptide.

In a recent study we demonstrated that a synthetic peptide representing residues 124-147 of the major protein of hepatitis B surface Ag (HBsAg) undergoes spontaneous oligomerization to reconstruct one or more conformational group-specific determinants on HBsAg. The present study was undertaken to identify and characterize the HBsAg-related antigenic determinants on this oligomeric peptide (peptide OS[124-147]). A panel of nine analogs of this peptide was generated by either deleting, substituting, or chemical side chain modification of specific amino acid residues. With HBsAg subtype-specific antisera a single "a" epitope was identified as one that includes Met133 and Lys141. In addition a "d" epitope toward the amino-terminal end of the sequence was also observed. Perturbation of certain amino acid residues was found to enhance a antigenicity and subsequent experiments indicated that maximal expression of this a antigenicity is dependent in part on accessibility of the Lys141 side chain and in part on the primary sequence. With a total of 50 human anti-HBsAg serum samples obtained from individuals vaccinated against hepatitis B, it was demonstrated that these sera recognize the Met133-Lys141-dependent a epitope as the dominant, and in many cases the only, determinant on peptide OS[124-147]. Finally, on immunization, peptide OS[124-147] elicits an anti-HBsAg response that is predominantly anti-a though a lesser contribution from an anti-d response was also obtained.     

DNA damage and repair in brain: relationship to aging.

The usefulness of conducting DNA damage and repair studies in a postmitotic tissue like brain is emphasized. We review studies that use brain as a tissue to test the validity of the DNA damage and repair hypothesis of aging. As far as the accumulation of age dependent DNA damage is concerned, the data appear to overwhelmingly support the hypothesis. However, attempts to demonstrate a decline in DNA repair capacity as a function of age are conflicting and equally divided. Possible reasons for this discrepancy are discussed. It is suggested that assessment of the repair capacity of neurons with respect to a specific type of damage in a specific gene might yield more definitive answers regarding the role of DNA repair potential in the aging process and as a longevity assurance system.