Distribution of gamma-glutamyl transpeptidase in the mouse epididymis and its response to acivicin

gamma-Glutamyl transpeptidase (gamma-GT), its substrate (GSH) and hydrolytic product (L-glutamic acid) were measured biochemically in mouse reproductive tissues. The epididymal caput and seminal vesicles showed the highest specific activities of gamma-GT, while GSH and L-glutamic acid were widely distributed in all tissues. Histochemically, gamma-GT displayed a strong apical and supranuclear reaction and a moderate basal activity in the ductuli efferents, a weak luminal reaction in the first, a moderate apical reaction in the second and a strong apical and supranuclear reaction in the third segment of the epididymal caput. In the epididymal corpus and cauda, the gamma-GT reaction was confined to the tubular lumina but an apical reaction was also present in the cauda. The daily administration of acivicin (12 mg/kg body weight), an irreversible inhibitor of gamma-GT, for 14 days resulted in a 60% suppression of the enzyme activity in the epididymal caput, while the gamma-GT inhibition in the kidney was greater than 95%. The treatment caused no change in the activity of alanyl aminopeptidase. Histochemically, the basal and supranuclear gamma-GT activities in the ductuli efferents and the third epididymal segment were suppressed, but the apical reactions were maintained. The in-vivo suppression of epididymal gamma-GT activity may have implications in the control of post-testicular sperm maturation.     

Mobility and cooperation among nomadic shepherds: The case of theRaikas

This paper describes and then analyzes the decision-making arrangements that prevail among the Raikas—nomadic shepherds from Western India. The paper suggests, using a simple analytical framework, that the existing distribution of decision-making during migration helps the Raikasto utilize available economies of scale, represent the different interest groups in their collectives, and control their decision-makers. At the same time, the ordinary shepherds in the camp are able to extract a comfortable subsistence from a complex and harsh environment by delegating much of their decision-making responsibilities to the leaders in the camp. To the extent shepherds in other parts of the world migrate over long distances and must confront similar issues of delegation of responsibilities and control over decision-makers, the analysis holds general relevance.     

Enzymatic labeling of nucleic acids

Enzymatic labeling of nucleic acids is a fundamental tool in molecular biology with virtually every aspect of nucleic acid hybridization technique involving the use of labeled probes. Different methods for enzymatic labeling of DNA, RNA and oligonucleotide probes are available today. In this review, we will describe both radioactive and nonradioactive labeling methods, yet the choice of system for labeling the probe depends on the application under study.     

Demonstration of five major glycoproteins in myelin and myelin subfractions.

Myelin was found to contain five major glycoproteins with molecular weights of 120000, 95000, 88000, 43000 and 38000. Light myelin contained only 5-7% of the amount of these glycoproteins in whole myelin, whereas heavy myelin and the membrane fraction contained amounts nearly identical with whole myelin. Since all the major and minor glycoproteins, with the exception of 120000-mol-wt. glycoprotein, were detected only after treating the myelin membrane with neuraminidase, N-acetylneuraminic acid is a terminal sugar residue in these glycoproteins.     

Effect of 7-azatryptophan on heterocyst differentiation inAnabaena doliolum Bharadwaja

The effect of DL-7-azatryptophan, an analogue of tryptophan, has been studied on the heterocyst spacing pattern and the probability of proheterocyst regression inAnabaena doliolum. 7-azatryptophan suppressed growth and induced heterocyst differentiation in nitrogen-free medium. In ammonium (1 mM), nitrite (2 mM) and nitrate (2 mM) supplemented media, it caused proheterocyst regression with a frequency of 100%, 35% and 10% respectively. The role of azatryptophan in nitrogen metabolism has been discussed in relation to ammonia-uptake study.     

Studies on some enzymes relevant to citric acid accumulation by Aspergillus niger

Enzymatic studies have been performed on a local strain of Aspergillus niger to find a correlation with citric acid accumulation. The activity of aconitase [aconitate hydratase, citrate(isocitrate) hydrolyase, EC 4.2.1.3] and isocitrate dehydrogenase (NADP⁺) [threo-d_s-isocitrate:NADP⁺ oxidoreductase (decarboxylating) EC 1.1.1.42] decreased after 4 days whereas that of citrate synthase [citrate oxaloacetate-lyase (pro-3S-CH₂COO^?→acetylCoA), EC 4.1.3.7] did so after 8 days, when citric acid accumulation in the medium reached a maximum (45.9 mg ml^?1). In vitro studies with mycelial cell-free extracts demonstrated inhibition of citrate synthase activity by sodium azide and potassium ferricyanide on both the 4th and 8th days. Aconitase was inhibited by sodium arsenate, sodium fluoride, iodoacetic acid and potassium ferricyanide only on the 4th day. Isocitrate dehydrogenase (NADP⁺) activity on the 4th and 8th days was inhibited by iodoacetic acid but was stimulated by potassium ferricyanide. The possible existence of isozyme species of these enzymes is discussed.     

NMR spectroscopy in the structural elucidation of oligosaccharides and glycosides.

The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group, in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.