B.Sc., M.Sc. University of Allahabad
Ph.D. University of California, Davis
Room P8474, (778) 782-4850
srivasta@sfu.ca

Current Research Program

Our work has established the presence of soluble protein receptors in several plants which bind [³ H]GA₁ and [³ H]GA₄ with high affinity. The binding is exchangeable and biologically specific; the affinity constants of different GAs bear a relationship to their activities in the respective bioassays. From competition studies we have deduced certain features of the Ga-binding site of the receptor. We are now trying to get pure preparations of these receptors both by biochemical and molecular biological techniques in order to sequence them and to study the details of molecular interaction between the hormone and the receptor on the one hand and the hormone-receptor complex and the regulatory sequences of the responsive genes on the other. GA-insensitive mutants such as Rht3 wheat are being used in the study.

Physiology, chemistry and biochemistry of seaweeds. Our work has included carbon fixation, nitrogen nutrition, photoassimilate transport, and iodine uptake and transport in kelps. As well, the chemical constituents including minerals, mannitol, yield and quality of alginate, fucoidan, fatty acids have been measured year round and related to age of plants and environmental parameters. More recent work deals with purification and characterization of floridoside phosphate synthase, a key enzyme in the synthesis of floridoside and seasonal changes in chemical constituents of Porphyra (Nori) a commercially important seaweed.

Selected Publications

Srivastava, L.M. and K.A. Sechley. 1991. In search of a gibberellin receptor. Proc. Iowa Acad. Sci. 98: 51-62.

Meng, J., K.G. Rosell and L.M. Srivastava. 1987. Chemical characterization of floridosides from Porphyra perforata. Carbohyd. Res. 161: 171-189.

Yalpani, N. and L.M. Srivastava. 1985. Competition for in vitro [3 H]-gibberellin A4 binding in cucumber by gibberellins and their derivatives. Plant Physiol. 79: 963-967.

Wheeler, W.N., R.G. Smith and L.M. Srivastava. 1984. Seasonal photosynthetic performance of Nereocystis luetkeana. Can. J. Bot. 62: 664-670.

Keith, B., S. Brown and L.M. Srivastava. 1982. In vitro binding of gibberellin A4 to extracts of cucumber using DEAE-cellulose filters. Proc. Natl. Acad. Sci. U.S.A. 79: 1515-1519.

[³H] GA₄ binding by isolated nuclei. Different concentrations of nuclei from 40 to 60% Percoll interface were incubated in 10 nM [³H] GA₄ with or without 1 uM GA₄ to dermine total and specific binding. The DEAE-filter assay was used to separate [³H] GA₄ bound from free.