TRH and TRH-OH in the pancreas of adult and newborn rats

TRH and its metabolite TRH-OH have been measured by specific radioimmunoassays in acid extracts of pancreas in adults and developing rats. TRH and TRH-OH immunoreactivity had the same ontogenic pattern with a maximal concentration on day 4 followed by a progressive return towards adult levels on day 20. A significant linear correlation was found between TRH levels and the TRH/TRH-OH ratio. The range of TRH/TRH-OH ratio varied from 136 +/- 1.6, at the peak of concentrations of both peptides, to 18 +/- 3.9 on day 20. Pancreatic TRH and TRH-OH had the same elution pattern as corresponding synthetic peptides both on Biogel P2 and high-pressure liquid chromatography. The origin of TRH-OH as well as its potential function need further investigations.     

Interaction of Opiates with Opioid Binding Sites in the Bovine Adrenal Medulla: I. Interaction with δ and μ Sites

In the present study we examined the interaction of opiates with the delta and mu opioid binding sites in the bovine adrenal medulla. [3H][D-Ala2, D-Leu5]-enkephalin ( [3H]DADLE) in the presence of saturating concentrations of morphiceptin was used to analyze delta site interactions, whereas either [3H]DADLE in the presence of saturation concentrations of [D-Ser2, Leu5]-enkephalin-Thr6 (DSLET) or [3H][D-Ala2, Me-Phe4, Gly5-ol]-enkephalin ( [3H]DAGO) was used for the determination of mu sites. Both binding sites were found to interact stereoselectively with opiates. The binding was affected differentially by proteolytic enzymes (trypsin, alpha-chymotrypsin, pepsin), N-ethylmaleimide, and A2-phospholipase. Kinetic and equilibrium binding studies revealed that in each case radiolabeled opiates interact with one class of binding sites, following simple second-order bimolecular kinetics. Competition for binding by opiates and opioid peptides confirmed the delta and mu selectivity of these sites. Monovalent (Na+, Li+, K+) and divalent (Mg2+, Mn2+, Ca2+) ions interacted differentially with these two binding sites: In general, monovalent cations affected preferentially the apparent number of binding sites, whereas divalent ions modified the equilibrium dissociation constant. Furthermore, positive or negative cooperativity and an apparent heterogeneity of binding sites were detected under some ionic conditions.     

The presence and photoregulation of protochlorophyllide reductase in green tissues

Summary The enzyme protochlorophyllide (pchlide) reductase has been identified amongst the peptides, resolved by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), of chloroplast membranes from oat and barley plants. In support of this identification the enzymic activity associated with the enzyme has also been measured in the same preparations. A higher level of enzyme was found in plants which had been darkened prior to extraction. Based on this data, mechanisms for the light regulated diurnal variation of the reductase are discussed.     

Isolation and characterization of Pediococcus halophilus from salted anchovies (Engraulis anchoita)

The presence of bacteria in salted anchovies during and at the end of the curing process was investigated. Attempts to isolate bacteria under aerobic or anaerobic conditions led to the isolation of only bacteria of the genus Pediococcus which were identified as Pediococcus halophilus. The isolates correspond to a rather heterogeneous group in which some of the members differ in some biochemical tests from the types described in the literature.     

Variants within the yeast Ty sequence family encode a class of structurally conserved proteins.

The Ty transposable elements of Saccharomyces cerevisiae form a heterogeneous family within which two broad structural classes (I and II) exist. The two classes differ by two large substitutions and many restriction sites. We show that, like class I elements a class II element, Tyl-17, also appears to contain at least two major protein coding regions, designated TYA and TYB, and the organisational relationship of these regions has been conserved. The TYA genes of both classes encode proteins, designated p1 proteins, with an approximate molecular weight of 50 Kd and, despite considerable variation between the TYA regions at the DNA level, the structures of these proteins are remarkably similar. These observations strongly suggest that the p1 proteins of Ty elements are functionally significant and that they have been subject to selection.     

Nucleotide sequence characterization of Ty 1-17, a class II transposon from yeast

We have determined the nucleotide sequence of a class II yeast transposon (Ty 1-17) which is found just centromere-distal to the LEU2 structural gene on chromosome III of Saccharomyces cerevisiae. The complete element is 5961 bp long and is bounded by two identical, directly repeated, delta sequences of 332 bp each. The sequence organization indicates that Ty 1-17 is a retrotransposon, like the class I elements characterized previously. It contains two long open reading-frames, TyA (439 amino acids) and TyB (1349 amino acids). In this paper, the sequences of the two classes of yeast transposon are compared with one another and with analogous elements, such as retroviral proviruses, cauliflower mosaic virus and copia sequences. Features of the Ty 1-17 sequence which may be important to its mechanism of transposition and its genetic action are discussed.     

β-D-galactosidase ofLactobacillus species

The activity of β-D-galactosidase was studied in 13 strains of lactobacilli (groupsStreptobacterium, Thermobacterium andBetabacterium). Using 2-nitrophenyl galactopyranoside as substrate, the enzyme activity varied with the strain. The values found in theThermobacterium group were superior to those in theStreptobacterium group. The optimum pH for the species belonging to theThermobacterium group was uniform, in contrast to the ph for those from theStreptobacterium which varied according to the species. The optimum temperature was quite uniform within each group and higher in theStreptobacterium. Lactose acted as a competitive inhibitor. MgCl₂ protected the enzyme from thermal denaturation. The calcium ions inhibited the activity in all cases. The behaviour of the protectors of the SH groups varied according to the strain. 6-Phospho-β-D-galactosidase activity was also determined, levels lower than β-D-galactosidase were found, except inLactobacillus plantarum ATCC 8014 and 14917.     

Cyclic AMP levels during induction and repression of cellulase biosynthesis in Thermomonospora curvata.

Specific cellulase production rates (SCPR) were compared with intracellular cyclic AMP (cAMP) levels in the thermophilic actinomycete, Thermomonospora curvata, during growth on several carbon sources in a chemically defined medium. SCPR and cAMP levels were 0.03 U (endoglucanase [EG] units) and 2 pmol per mg of dry cells, respectively, during exponential growth on glucose. These values increased to about 6 and 25, respectively, during growth on cellulose. Detectable EG production ceased when cAMP levels dropped below 10. Cellobiose (usually considered to be a cellulase inducer) caused a sharp decrease in cAMP levels and repressed EG production when added to cellulose-grown cultures. 2-deoxy-D-glucose, although nonmetabolizable in T. curvata, depressed cAMP to levels observed with glucose, but unlike glucose, the 2DG effect persisted until cells were washed and transferred to fresh medium. SCPR values and cAMP levels in cells grown in continuous culture under conditions of cellobiose limitation were markedly influenced by dilution rate (D). The maxima for both occurred at D = 0.085 (culture generation time of 11.8 h). When D was held constant and cellobiose concentration was increased over a 14-fold range to support higher steady state population levels, SCPR values decreased about fivefold, indicating that extracellular catabolite accumulation may be a factor in EG repression. The role of cAMP in the mechanism of this repression appears to be neither simple nor direct, since large changes (up to 200-fold) in SCPR accompany relatively small changes (10-fold) in cellular cAMP levels.     

Binding of human lymphocyte-specific monoclonal antibodies to common marmoset lymphoid cells

Commercially available monoclonal antibodies which bind to human lymphocyte subsets were screened for their ability to bind to lymphoid cells from the common marmoset Callithrix jacchus. Anti-Leu-5 and T11 were the only pan T-cell antibodies which reacted strongly. None of the antibodies which bind human lymphocytes of the helper/inducer subpopulation reacted with C. jacchus cells and only one antibody, T8, specific for the cytotoxic/suppressor subset, bound to the marmoset cells. The two antibodies tested which bind human B cells, B1 and anti-HLA-DR, were also reactive with marmoset cells. The cellular specificity of the T11, T8, and B1 antibodies was determined by dual binding studies on the fluorescence-activated cell sorter. The B1 antibody bound only Ig+ cells and all Ig+ cells were B1+. The T11 and T8 antibodies bound only to Ig- marmoset lymphoid cells and, as in the human, all T8+ marmoset cells were also T11+. Thus, using these monoclonal antibodies in the common marmoset one can identify three populations of lymphoid cells: (1) T11+, T8+ cells; (2) T11+, T8- cells; (3) B1+ cells.