Extracts from cells of rhodospirillum
rubrum cultured photohetero-
trophically under anaerobic conditions exhibits an NAD+-dependent , soluble aldehyde dehydrogenase which catalyses the dehydrogenation of acetaldehyde to acetate (aldehyde: NAD+ oxidoreductase . EC 1.2, 1.3 ) the enzyme is NAD+ specific with thw aldehydes tested, no activity is observed with NADP+ or in the absence of NAD+. Sulfhydryl reagents markedly increase the aldehyde dehydrogenase activity. For initial reaction rates of acetaldehyde dehydrogenation the optimum activity of the enzyme is between pH 9.0 to 9.5 , with an apparent michaelis constant for acetaldehyde of
10-5 M. no requirements for potassium or
orthophosphate are apparent . extracts from cells cultured anaerobically on ethanol, as the sole carbon, source, exhibit five to ten times the specific aldehyde dehydrogenase activity compard to cell cultured on malate plus glutamate . this increase in the specific activity of aldehyde dehydrogenase preparations from cells cultured on ethanol is inhibited by proflavin or chloramphenicol . the evidence suggests that the aldehyde dehydrogenase in R. rubrum ia sn inducible enzyme.
The Libyan material of pennisetum
divisum sensu lato and P. setaceum (Forssk.) chiov was studied embryologically , both the species demonstratd facultative apomixes. The frequency of apomictic and multiple embryo-sacs in P. divisum was found to be much higher than in P. setaceum . however, polyembryony was observed in P.setaceum only.
Fossil dicotyledonous wood belonging to
genus cynometra of family leguminosate and genus Pterocarya of family juglandaceae are described. Two new species cynometroxylon ranikotensis sp. Nov., pterocaryoxylon ranikotensis sp. Nov. are established.
Residual toxicity of prometryne and fluometuron was assayed in six different soils after three months of herbicidal treatment . the persistence of herbcides varied in different soils, fluometuron was more persistent than prometryne .
residual toxicity of prometryne was completely lost in heavy soil. In general, residual toxicity of the herbicides was inversely related to the amount of colloidal material in soil. Degradation of herbicides was also associated with soil pH. Formulate for the estimation of
Nitrogen concentration increased in the shoot of young rice seedlings fed with N15 and 14CO2 but it decreased in N-starved roots . the assimilation of 14CO2 was
limited in N-starved plants compared to N-
fertilized plants.
