Insulin sensitivity of liver glycogen synthase b into a conversion

Summary Liver glycogen synthase b phosphatase, chromatographically separable from phosphorylase a phosphatase, is decreased in 48-hour alloxan diabetic rats. The phosphatase activities are measured in an in vitro system using exogenous isolated phospho-enzyme as substrates with added phosphatases. Synthase and phosphorylase phosphatases were shown to have differential catalytic properties by their reactivity in the presence of Pi, the heat-stable inhibitor of phosphorylase phosphatase and after incubation with added cAMP-dependent protein kinase.Supported by NIH Grants HD-07788, AM-21149 and, in part, by grants from the Greater St. Louis Diabetic Childrens Welfare Association and the American Diabetes Association, N.Y.     

Enhanced level and metabolic regulation of methionyl-transfer ribonucleic acid synthetase in different strains of Escherichia coli K-12.

The methionyl-transfer ribonucleic acid (tRNA) synthetase of Escherichia coli K-12 eductants carrying P2-mediated deletions in the region of the structural gene of this enzyme was investigated. No structural alteration of this enzyme was observed in three eductants examined. These were isolated from strain AB311, which had a threefold higher level of methionyl-tRNA synthetase than most haploid strains examined. In two of the three eductants studied, the level of this enzyme was twofold higher than in their parental strain regardless of growth conditions used. In contrast, isoleucyl-, leucyl-, and valyl-tRNA synthetases had similar levels in all strains examined. Like valyl-tRNA synthetase, but to a lesser extent, methionyl-tRNA synthetase was subject to metabolic regulation. Coupling between the level of methionyl-tRNA synthetase and growth rate was observed even in strains that had an enhanced level of methionyl-tRNA synthetase. These results suggest that the formation of methionyl-tRNA synthetase remains subject to metabolic regulation even when the repression-like mechanism that controls the synthesis of this enzyme is altered. In addition, we report that in the merodiploid strain EM20031, which was haploid for the valyl-tRNA synthetase structural gene and diploid for the structural genes of methionyl-tRNA synthetase and D-serine deaminase, the levels of these latter two enzymes varied to a minor yet significant extent with the phosphate concentration of the culture medium; under the same conditions, the level of valyl-tRNA synthetase remained unchanged. Moreover, no variation of the levels of these three enzymes in response to phosphate was observed in the haploid strain HfrH. These results indicate that in the merodiploid strain EM20031, which carries the episome F32, the number of episomes per chromosome varies to some extent according to the phosphate concentration of the culture medium.     

Nomenclatural adjustments in some European monocotyledons

New nomenclatural combinations are validated for fifteen taxa belonging to the generaDanthonia, Stipa, Lolium, Phippsia, Elymus, Schoenoplectus andAllium.     

Transparency improves concealment in cryptically coloured moths

Predation is a ubiquitous and strong selective pressure on living organisms. Transparency is a predation defence widespread in water but rare on land. Some Lepidoptera display transparent patches combined with already cryptic opaque patches. A recent study showed that transparency reduced detectability of aposematic prey with conspicuous patches. However, whether transparency has any effect at reducing detectability of already cryptic prey is still unknown. We conducted field predation experiments with free avian predators where we monitored and compared survival of a fully opaque grey artificial form (cryptic), a form including transparent windows and a wingless artificial butterfly body. Survival of the transparent forms was similar to that of wingless bodies and higher than that of fully opaque forms, suggesting a reduction of detectability conferred by transparency. This is the first evidence that transparency decreases detectability in cryptic terrestrial prey. Future studies should explore the organization of transparent and opaque patches in animals and their interplay on survival, as well as the costs and other potential benefits associated with transparency on land.     

Altered expression of the PTR/NRT1 homologue OsPTR9 affects nitrogen utilization efficiency,growth and grain yield in rice

The plant PTR/NRT1 (peptide transporter/nitrate transporter 1) gene family comprises di/tripeptide and low‐affinity nitrate transporters; some members also recognize other substrates such as carboxylates, phytohormones (auxin and abscisic acid), or defence compounds (glucosinolates). Little is known about the members of this gene family in rice (Oryza sativa L.). Here, we report the influence of altered OsPTR9 expression on nitrogen utilization efficiency, growth, and grain yield. OsPTR9 expression is regulated by exogenous nitrogen and by the day‐night cycle. Elevated expression of OsPTR9 in transgenic rice plants resulted in enhanced ammonium uptake, promotion of lateral root formation and increased grain yield. On the other hand, down‐regulation of OsPTR9 in a T‐DNA insertion line (osptr9) and in OsPTR9‐RNAi rice plants had the opposite effect. These results suggest that OsPTR9 might hold potential for improving nitrogen utilization efficiency and grain yield in rice breeding.