Physiology of intracellular symbiotes ofStegobium paniceum L. with special reference to amino acid requirements of the host

Résumé Les auteurs ont soumis des larves deStegobium paniceum L. à un régime contenant seulement des acides aminés. Ils ont aussi constaté expérimentalement que la levure, de même que les symbiontes intracellulaires fournissent des acides aminés en quantités variables selon l'hôte.     

Abrupt changes in the Asian southwest monsoon during the Holocene and their links to the North Atlantic Ocean

During the last ice age, the Indian Ocean southwest monsoon exhibited abrupt changes that were closely correlated with millennial-scale climate events in the North Atlantic region, suggesting a mechanistic link. In the Holocene epoch, which had a more stable climate, the amplitude of abrupt changes in North Atlantic climate was much smaller, and it has been unclear whether these changes are related to monsoon variability. Here we present a continuous record of centennial-scale monsoon variability throughout the Holocene from rapidly accumulating and minimally bioturbated sediments in the anoxic Arabian Sea. Our monsoon proxy record reveals several intervals of weak summer monsoon that coincide with cold periods documented in the North Atlantic region--including the most recent climate changes from the Medieval Warm Period to the Little Ice Age and then to the present. We therefore suggest that the link between North Atlantic climate and the Asian monsoon is a persistent aspect of global climate.     

Purification and properties of heat-resistant exotoxin produced by Macrophomina phaseolina (Tassi) Goid in culture.

A partially purified preparation of a water-soluble, heat-resistant, nonspecific exotoxin produced by a strain of Macrophomina phaseolina, isolated from Phaseolus mungo L. could reduce Cu++ ions and produced a red colour with 2,4-dinitrophenyl hydrazine reagent. It caused inhibition of seed germination, wilting of cult seedlings, stunted growth of young seedlings and loss of permeability of the cell membrane. Seedlings of P. mungo, grown in presence of the toxin showed a slight increase in the contents of protein and total RNA over control, but a significant increase in the specific activities of F-1, 6-BP aldolase and G-6-P isomerase.     

Similarity of the Cin1 repetitive family of Zea mays to eukaryotic transposable elements

It has been suggested that the middle repetitive class of sequences that make up a large proportion of the eukaryotic genome have been amplified and dispersed by DNA transposition. Transposition is a phenomenon first postulated by Barbara McClintock on the basis of her genetic analysis of mutants in Zea mays. Since then, DNA transposition has been studied genetically in various plant systems and is well documented on the molecular level in both prokaryotes and eukaryotes. This has included the isolation of DNA inserts at various loci in several plants; however, the prevalence of transposition in plants is not established. We report here DNA nucleotide sequence data which show that some members of the Cin1 middle repetitive family of maize have features characteristic of known transposable elements. One cloned Cin1 repeat has a 6-base pair (bp) perfect inverted repeat sequence at its ends. The terminal five base pairs (5' TGTTG . . . CAACA 3') are identical to the termini of Drosophila copia transposable elements. Two other Cin1 alleles are flanked by 5-bp direct repeats. A comparison is made with the long terminal repeat (LTR) of the copia-Ty1-retrovirus families of moveable genetic elements.     

Comparative studies of male genital structures of hybrids and their parental species

Zusammenfassung Körperfarbe und Strukturen des Genitalapparates sowie der Geschlechtskämme des 1. Beinpaares männlicher Hybriden aus reziproken Kreuzungen vonDrosophila bipectinata x D. malerkotliana werden beschrieben. Die Hybriden zeigen intermediäre Merkmale, wobei vergleichend die Körperfarbe mehrD. malerkotliana, die Geschlechtskämme mehrD. bipectinata ähnlich sind.

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Acknowledgments. The author is thankful to the U.G.C. for extending financial assistance and to Prof.J. P. Thapliyal, Head of the Department for facilities.