Changes in Some Enzyme Activities during Growth and Organogenesis in Dark-Grown Tobacco Callus Cultures

Enzymes involved in malate metabolism, viz., glutamic-oxalacetictransaminase, malate dehydrogenase, malic enzyme and phosphoenolpyruvatecarboxylase, had severalfold higher specific activities in organ-formingcallus cultures of tobacco compared to non-organ-forming cultures.These activities increased considerably during the days precedingshoot and root differentiation. While malate accumulated untilday 15 in non-organ-forming callus, it accumulated up to day6 in shoot-and root-forming callus. Total and reducing sugarsaccumulated until day 3 and declined thereafter in all the cultures.Thus, tobacco callus may utilize this pathway for deriving reducingpower which is required for organogenetic processes. (Received April 30, 1987; Accepted December 1, 1987)     

Study of Circadian Variation in the Efficacy of Aspirin as an Analgesic Agent in Experimental Animals

Circadian rhythmicity is present in almost every aspect of the living world and effects of drugs on various life forms are no exception. This study was undertaken to find out the circadian variation in the analgesic activity of aspirin and to correlate the variations with the blood levels of salicylate at that time. The model used was the application of radiant heat to the tail of rats for analgesic activity. Aspirin exhibited maximum activity when administered at 12:00 h, although this difference was not statistically significant. Also, there was no correlation between the levels of salicylate in the blood and the activity of aspirin. Due to the presence of this trend towards increased activity at 12:00 h, it may thus be worthwhile to conduct similar studies, in patients of chronic arthritis, in order to find out the time(s) at which, aspirin if administered will be most useful.     

Aromatic amino acid metabolism during organogenesis in rice callus cultures

The activity during root and shoot initiation of key enzymes involved in aromatic amino acid metabolism was examined in rice ( Oryza sativa L. cv. Bala) callus cultures. Increased activities of the enzymes quinate:NAD⁺ oxidoreductase (EC 1.1.1.24), shikimate kinase (EC 2.7.1.71), chorismate mutase (EC 5.4.99.5), anthranilate synthase (EC 4.1.3.27) and tryptophan synthetase (EC 4.2.1.20) were noticed in organ-forming callus compared to proliferating callus of rice, especially prior to the visible manifestation of form. These results suggest a correlation between organogenesis and the aromatic amino acid pathway.     

Callus induction and high frequency plant regeneration in Italian millet (Setaria italica)

Callus was induced from mature seeds of two cultivars of Setaria italica (L.) on Murashige and Skoog's medium (1962) supplemented with 2mg/l 2,4-D and 0.5 mg/l KN. Regenerating ability of the callus was better in the cultivar 315 compared to 212. Organogenesis was influenced not only by cytokinin, but also by the sucrose concentration in the medium. High frequency (80%) plant regeneration was achieved and quantified on the basis of callus fresh weight. The ability of the callus (cultivar 212) to regenerate whole plants was retained until the 5th passage, but during the 6th passage it declined considerably.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - KN Kinetin - BAP 6-benzylaminopurine - MS Murashige and Skoog basal medium