Acidic and basic protein contents in Gastrocnemii and pectoralis muscles of chick under denervation and work-induced stress conditions.

Biochemical estimation of acidic and basic proteins of chick gastrocnemii (G. externus, G. medius and G. internus) and pectoralis muscles has been done under normal, denervated and work stress conditions from 1-56 days of postnatal growth. The reciprocal relationship of the two protein groups is clearly established. It is evident that muscle denervation acts as a stimulant for proteosynthetic activities and probably may also be an inhibitory factor for protein degradative reactions. During work overload stress, the rapid growth of muscles has been related to high rate of contractile activity.     

Variability in T cell receptor V beta gene usage in human peripheral blood lymphocytes. Studies of identical twins, siblings, and insulin-dependent diabetes mellitus patients.

Recent studies focused on the diversity and molecular organization of the human TCR-beta complex have begun to establish the genetic basis for the potential repertoire of V beta specificities in T cells. The scope and variability of the actual repertoire derived from this potential repertoire, however, remains to be clarified. In this study, V beta usage by human peripheral T cells derived from serial samples of the same individual, identical twins, and the members of three nuclear families that include four members with insulin-dependent diabetes mellitus (IDDM) was assessed by both quantitative polymerase chain reaction and Northern blotting with V beta subfamily-specific probes. Samples taken from the same individual over a period of 21 months and analyzed in separate experiments indicated stability in the peripheral repertoire, whereas the similarity in peripheral V beta usage in a pair of identical twins suggested a strong role for genetics in shaping the peripheral T cell repertoire. In contrast, V beta usage in siblings and in unrelated individuals was observed to differ substantially. In particular, peripheral expression of V beta 3 and V beta 20 differed by more than sixfold among members of two different families. Segregation analysis of TCR and HLA haplotypes in these families suggested that variation in V beta 20 expression was TCR haplotype specific. Subsequent nucleotide sequence analysis of the V beta 20 gene segment in multiple members of these families revealed the presence of a null allele for V beta 20 expression. No consistent significant differences in V beta usage were observed in IDDM patients relative to their siblings or between identical twins discordant for IDDM. These results suggest that the repertoire of peripheral T cell specificities present in different individuals in human populations varies dramatically because of the effects of multiple factors, including TCR germ-line polymorphism.     

Substrate-Induced Stability of Glyceraldehyde 3-Phosphate Dehydrogenase from Mung Beans (Vigna radiata L.)

Time-dependent thermal inactivation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) present in the extract of mung beans at different periods of germination showed biphasic kinetics in the 12-h germinated seeds but single exponential decay at 24 h of germination. The glyceraldehyde 3-phosphate (G-3-P) concentration in the deproteinated extracts was found to increase with period of germination up to 36 h, parallel to that of GAPDH activity. G-3-P was found to offer protection of the enzyme against thermal inactivation and trypsin digestion. It is suggested that accumulation of G-3-P in germinating mung beans may be of physiological significance and it might offer protection to the enzyme in vivo against thermal inactivation and proteolysis.     

Exendin-4, a new peptide from Heloderma suspectum venom, potentiates cholecystokinin-induced amylase release from rat pancreatic acini.

We examined the actions of exendin-4, a new peptide isolated from Heloderma suspectum venom, on dispersed acini from rat pancreas. Exendin-4 caused a 3-fold increase in cAMP but did not alter cellular calcium concentration. Exendin-4-induced increases in cAMP were inhibited by an exendin-receptor antagonist, exendin (9-39)NH2, but not by VIP-receptor antagonists. Whereas up to 1 microM exendin-4 alone did not alter amylase release, potentiation of enzyme release was observed when the peptide (greater than 30 pM) was combined with cholecystokinin. Potentiation of amylase release was also observed when exendin-4 was combined with carbamylcholine, bombesin or a calcium ionophore, A23187. These results indicate that stimulation of exendin receptors on rat pancreatic acini causes an increase in cellular cAMP. Although this increase in cAMP alone does not result in amylase release, combination of exendin-4 with agents that increase cell calcium results in potentiation of amylase release.     

Conformational flexibility of dinucleoside dimers during unwinding from the B-form to an intercalation structure.

Intra-dinucleoside dimer conformational energy calculations were performed on a series of conformations corresponding to the unwinding of a dinucleoside dimer from the B-form type structure. Conformational states were characterized in terms of the distance, d, between parallel bases. All 16 possible sequences for (G) and (C) and/or (A) and (T) bases were considered. Both free space, and free space plus aqueous solvation energies were computed. It was found that the B-form like conformer is the most stable structures in free space and in an aqueous medium. However, the energy as function of d is base pair sequence dependent. This sequence dependence suggests a possible inherent specificity for intercalation of the dinucleoside dimer with a drug molecule.     

Selenium availability in berseem (Trifolium alexandrinum) as affected by selenium and phosphorus application

Summary The effect of selenium and phosphorus application on Berseem (Trifolium alexandrium) was studied in the green house. Each dose of selenium from O to 16 ppm decreased the dry matter yield of Berseem significantly at all the levels of applied phosphorus. Phosphorus stimulated the dry matter yield at all levels of selenium. Yields in the second cutting were of a higher order than in the first cut. Selenium application increased selenium and phosphorus content in Berseem, but at 8 and 16 ppm of selenium the phosphorus content decreased significantly. Sulphur concentration decreased with selenium application but application of phosphorus increased sulphur concentration showing synergetic effect.Studies on residual effect of selenium revealed that the application of 50 ppm of phosphorus increased the yield while that of 100 ppm decreased it. Selenium concentration which increased with increasing phosphorus was many fold higher in the first cutting than in the second cutting and similar was the trend with phosphorus and sulphur.     

Functional characterization of types of plasma membranes in cerebral cortex.

The cerebral cortex of normal oxygenated and of asphyxiated mice has been studied by freeze-fracturing technique with a twofold purpose. First, to investigate changes, if any, in the molecular organization of the plasma membrane of any specific cell type(s) that could be correlated with permeability changes thought to take place as a consequence of asphyxiation. Secondly, to attempt characterization of plasma membranes on the basis of the organization of their fractured faces. The decrease in the extracellular material in asphyxiated cerebral cortex seen in electron micrographs of thin sections could not be correlated with change(s), if any, in the molecular organization of the plasma membrane of any particular cell type. Plasma membranes of various types could be characterized on the basis of the arrangement of particles on the fractured faces. Some of these types correspond to identifiable cell processes, while others have not yet been identified with certainty. Fusion of synaptic vesicles with the presynaptic membrane is mediated through clustering of 100-150 A membrane-associated particles.