Aging and cerebral aminopeptidase activity

A comparative study of brain aminopeptidase activity between 18 month old male rats and young adults of 3 months has been carried out utilizing the arylamides Leu-, Arg-, Lys-, Tyr- and Asp-beta-naphthylamide as substrates. Statistical analysis of results showed no significant differences either in areas studied or for enzymatic activities detected when both ages were compared. Two different patterns of regional distribution of enzymatic activity were observed: One came to be as a result of the use of Lys-, Arg-, Leu- or Tyr-beta-naphthylamide and the other as a result of the use of Asp-beta-naphthylamide.     

Effects of cloprostenol, human chorionic gonadotropin and estradiol benzoate treatment on estrus synchronization in dairy cows

Two consecutive experiments were conducted. In Experiment 1, 24 Friesian lactating cows were randomly assigned to two groups. Cows in Group I received intramuscularly (i.m.) 500 mcg of cloprostenol, 1250 IU of human chorionic gonadotropin (hCG) and 5 mg of estradiol benzoate 12 h after cloprostenol treatment. Cows in Group II received 750 IU i.m. of hCG and 3 mg of estradiol benzoate 12 h after cloprostenol treatment. Treatment was given on Day 16 after estrus in both groups. All animals showed estrus within 24 to 48 h after cloprostenol treatment. The average interval from cloprostenol injection to the onset of estrus was not influenced by treatments. Four cows in Group I failed to ovulate and became cystic. In Experiment 2, 71 Friesian lactating cows were randomly assigned to two groups. Cows in Group I received 500 mcg i.m. of cloprostenol after corpus luteum detection by palpation per rectum. Cows in Group II received 500 mcg of cloprostenol plus 750 IU of hCG and 3 mg of estradiol benzoate 12 h after. When estrus ready for service was confirmed by rectal examination, cows were inseminated. The percentage of cows ready for service tended to be lower (P < 0.06) between cows in Group I (88%) and those in Group II (100%). The average interval from cloprostenol treatment to service was longest (P < 0.001) in Group I (78.7 h +/- 14.9, X +/- SD) vs Group II (48 h +/- 2.9). The degree of readiness for service synchrony was lowest (P < 0.001) in Group I (59.3%) vs Group II (94.2%). The pregnancy rates of cows synchronized or treated were not altered by hCG-estradiol benzoate treatment (P > 0.25). These results suggest that in dairy cows treated with cloprostenol following palpation per rectum of a corpus luteum and then with 750 IU of hCG and 3 mg of estradiol benzoate 12 h later, a single fixed-time insemination at 48 h after cloprostenol treatment should be performed.     

Comparative effects of tumour necrosis factor-alpha (cachectin), interleukin-1-beta and tumour growth on amino acid metabolism in the rat in vivo. Absorption and tissue uptake of alpha-amino[1-14C]isobutyrate.

Incubation of a membrane preparation enriched in Photosystem Two (PSII) at alkaline pH inhibited the water-splitting reactions in two distinct steps. Up to pH 8.5 the inhibition was reversible, whereas at higher alkalinities it was irreversible. It was shown that the reversible phase correlated with loss and rebinding of the 23 kDa extrinsic polypeptide. However, after mild alkaline treatments a partial recovery was possible without the binding of the 23 kDa polypeptide when the assay was at the optimal pH of 6.5 and in a medium containing excess Cl-. The irreversible phase was found to be closely linked with the removal of the 33 kDa extrinsic protein of PSII. Treatments with pH values above 8.5 not only caused the 33 kDa protein to be displaced from the PSII-enriched membranes, but also resulted in an irreversible modification of the binding sites such that the extrinsic 33 kDa protein could not reassociate with PSII when the pH was lowered to 6.5. The results obtained with these more extreme alkaline pH treatments support the notion that the 23 kDa protein cannot bind to PSII unless the 33 kDa protein is already bound. The differential effect of pH on the removal of the 23 kDa and 33 kDa proteins contrasted with the data of Kuwabara & Murata [(1983) Plant Cell Physiol. 24, 741-747], but this discrepancy was accounted for by the use of glycerol in the incubation media.     

Development of an enzymatic procedure to produce high-protein amaranth flour

Summary A basic procedure was developed to produce high-protein amaranth flour (HPAF) using a commercial preparation of heat-stable alpha-amylase. Slurries (20%, w/v) of gelatinized whole flour were liquefied at 70 and 90°C, pH 6.5, 0.1% (w/v) enzyme concentration and 30 min hydrolysis time. Protein content of raw flour was increased from 15 to 29.6 or 39.3% at liquefaction temperatures of 70 or 90°C, respectively. Some physicochemical and functional properties of HPAF were assessed. HPAF might be used as a dry milk extender.     

The effect of glucose and ammonium sulfate on kinetic acidification by heterogeneous mixed culture

Summary The effect of glucose and ammonium sulfate concentration on the kinetics of lactic acid formation by a heterogeneous mixed culture was evaluated by the sole product formation using the Gompertz model, which can be used to define culture media composition taking into account product accumulation and acidification rate constant. A compromise between ionic inhibition and nitrogen limitation was found by using ammonium sulfate as nitrogen source. The sugar tolerance was similar to that in exenic cultures.     

Discrepancy in hormone binding and information transfer between sister cells of Tetrahymena clones

Tetrahymena cells treated with insulin in mass cultures were separated to single-cell clones or one of the "sister-cells" of dividing Tetrahymena (in single-cell culture) was treated with insulin. In both cases the FITC-insulin binding of sister-cells were compared. The insulin imprinting significantly increased the insulin binding of cells. There was also a significant difference between the imprinted and not imprinted sisters as well as between the not imprinted sisters. This demonstrates the existence of a difference (in hormone binding) between sister-cells and justifies that the information of the first hormone treatment (imprinting) is not equally divided between the sister-cells.     

Cooperative binding of primycin and gramicidin on erythrocyte membranes. A cation transport study

In this paper the authors present a comparative study of the actions of the antibiotics primycin and gramicidin on the erythrocyte membrane permeability. It has been found that both antibiotics have a nonlinear effect on the membrane permeability. Above a threshold antibiotic concentration, which is characteristic of the type of the antibiotic, the cation permeability of the erythrocyte membranes increases sharply. In the range of nonlinearity the transport-kinetic curves level off before achieving the equilibrium radioactive ion distribution between the extra- and intracellular spaces. A stochastic model of the cooperative and aspecific incorporation of antibiotic molecules into the membrane explains the experimental findings. The authors conclude that membrane permeability increases at the places where two or more antibiotic molecules form aggregates in the membrane.     

Fatty acids bound to vitamin D-binding protein (DBP) from human and bovine sera

Human and bovine vitamin D-binding protein (DBP) have been isolated from serum by a method that does not involve denaturing steps. This method includes Cibacron Blue-Sepharose chromatography, gel filtration, DEAE-Sephadex chromatography and albumin immunoadsorption. Analysis of fatty acids bound to the isolated human and bovine DBP showed molar ratios of fatty acid to protein of 0.4 and 1.3 respectively meanwhile human and bovine albumin have bound 1.8 and 1.5 moles per mol respectively. Most of fatty acids bound to human and bovine DBP are monounsaturated and saturated, mainly oleic and palmitic acids, which together account for 50% of the total of fatty acids in both species. By contrast, polyunsaturated fatty acids represented a minor component, less than 5%.     

Aliphatic hydrocarbons obtained from iron carbides: Possible stellar and meteoritic implications

Origins of Life and Evolution of Biospheres -     

Fluorescent staphylococci as microbeads

Fixed bacteria of the protein A-rich Cowan I Staphylococcus strain were labelled with fluorescein isothiocyanate and used as the second-step reagent in an indirect immunofluorescent assay of specific cell-surface antigen expression. The results are documented with fluorescence microscopy and flow cytometry.