Jawaharlal Nehru University

About: Jawaharlal Nehru University is a education organization based out in New Delhi, India. It is known for research contribution in the topics: Population & Candida albicans. The organization has 6082 authors who have published 13455 publications receiving 245407 citations. The organization is also known as: JNU.

Temperature-stress-induced impairment of chlorophyll biosynthetic reactions in cucumber and wheat

Abstract: Chlorophyll (Chl) biosynthesis in chill (7°C)- and heat (42°C)-stressed cucumber (Cucumis sativus L. cv poinsette) seedlings was affected by 90 and 60%, respectively. Inhibition of Chl biosynthesis was partly due to impairment of 5-aminolevulinic acid biosynthesis both in chill- (78%) and heat-stress (70%) conditions. Protochlorophyllide (Pchlide) synthesis in chill- and heat-stressed seedlings was inhibited by 90 and 70%, respectively. Severe inhibition of Pchlide biosynthesis in chill-stressed seedlings was caused by inactivations of all of the enzymes involved in protoporphyrin IX (Proto IX) synthesis, Mg-chelatase, and Mg-protoporphyrin IX monoester cyclase. In heat-stressed seedlings, although 5-aminolevulinic acid dehydratase and porphobilinogen deaminase were partially inhibited, one of the porphyrinogen-oxidizing enzymes, uroporphyrinogen decarboxylase, was stimulated and coproporphyrinogen oxidase and protoporphyrinogen oxidase were not substantially affected, which demonstrated that protoporphyrin IX synthesis was relatively more resistant to heat stress. Pchlide oxidoreductase, which is responsible for phototransformation of Pchlide to chlorophyllide, increased in heat-stress conditions by 46% over that of the control seedlings, whereas it was not affected in chill-stressed seedlings. In wheat (Triticum aestivum L. cv HD2329) seedlings porphobilinogen deaminase, Pchlide synthesis, and Pchlide oxidoreductase were affected in a manner similar to that of cucumber, suggesting that temperature stress has a broadly similar effect on Chl biosynthetic enzymes in both cucumber and wheat.

Grain size and geochemical partitioning of heavy metals in sediments of the Damodar River – a tributary of the lower Ganga, India

Abstract: The distribution of Si, Al, Fe, Mn, Cu, Zn, Ni and Cr in different grain-size fractions and geochemical association of Fe, Mn, Cu and Zn with Cu>Mn>Fe. The exchangeable fraction of the Damodar sediments contains very low amounts of heavy metals suggesting poor bioavailability of metals.