Effect of α-Methylphenylalanine and Phenylalanine on Brain Polyribosomes and Protein Synthesis

Abstract: A chronic hyperphenylalanemia was effectively produced in developing mice by daily administrations of phenylalanine (2 mg/g body wt) and a phenylalanine hydroxylase inhibitor α-methyl-D, L-phenylalanine (0.43 mg/g body wt). The presence of α-methylphenylalanine in newborn mice inhibited 65–70% of hepatic phenylalanine hydroxylase activity within 12 h. Since this maximum inhibition persisted for 24 h or longer, decreased enzyme activity was maintained by daily administrations. Whereas concentrations of phenylalanine increased approximately 40-fold in both plasma and brain following injection of α-methylphenylalanine and phenylalanine, plasma levels of tyrosine were not altered significantly. Concomitant with changes in phenylalanine concentrations we observed the brain polyribosomes' disaggregation, which reached a maximum 3 h after injection and persisted as long as 18 h. Polyribosomes did not become refractory to as many as 10 daily injections of α-methylphenylalanine and phenylalanine. In addition to polyribosome disaggregation, chronic hyperphenylalanemia reduced the rates of polypeptide chain elongation on polyribosomes isolated from brain homogenates.     

Isolation of 2'',3''-Cyclic Nucleotide 3''-Phosphodiesterase from Human Brain

Abstract: The enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (EC 3.1.4.37) has been isolated from an acetone powder of human subcortical white matter. The yield was about 11 mg from 28 g of powder and a specific activity of 213 unitdmg protein was obtained using 2',3'-cyclic CMP as the substrate. A major protein band of molecular weight approx. 96,000 was found by gel electrophoresis under nonreducing conditions. However, two distinct protein bands of molecular weight 46,000 ± 1400 and 48,000 ± 1400 were observed when the protein sample was reduced with 10 mM-dithiothreitol and subjected to electrophoresis in more restrictive 12-15% polyacrylamide-SDS gels. This molecular weight is lower than that previously reported for the bovine enzyme. Antibodies against the purified human enzyme have been raised in New Zealand white rabbits.     

Survival of cohorts in a fluctuating population of the vole Microtus townsendii

Survival patterns of cohorts are described during a population cycle of the vole Microtus townsendii near Vancouver, British Columbia, Canada. A two–year live–trapping study on both enclosed and unfenced populations showed that cohorts during the increase phase of growth lived longest and had the best survival. Smaller voles in the peak density spring cohort had poor survival, but survival increased during the peak density summer. Survival of cohorts in the decline phase breeding season was very poor. The suggestions are made that changes in spacing behaviour may cause changes in cohort survival and that the causes of rapid changes in survival need to be determined.     

Ecology ofAeromonas hydrophila in a South Carolina cooling reservoir

Densities ofAeromonas hydrophila were determined monthly from December 1975 to December 1977 in a South Carolina cooling reservoir which receives heated effluent from a single nuclear production reactor. Selected water quality parameters and prevalence of red-sore disease among largemouth bass were monitored simultaneously.Higher densities ofA. hydrophila were observed in areas of the reservoir receiving effluent from the reactor. Densities ofA. hydrophila generally were heterogeneous in the water column. The sediments had lower densities ofA. hydrophila than water immediately above.A. hydrophila could not be isolated from sediments greater than 1 cm from the water interface. Temperature, redox potential, pH, and conductivity were all significantly correlated with densities ofA. hydrophila in the water column. The temporal and spatial distribution and abundance ofA. hydrophila in water were not related to total organic carbon, dissolved organic carbon, particulate organic carbon, inorganic carbon, or dissolved oxygen. High densities ofA. hydrophila were observed in mats of decomposingMyriophyllum spicatum and, enterically, in largemouth bass, several other species of fish, turtles, alligators, and snails. The greatest densities ofA. hydrophila in water occurred during March and June with a second peak in October. The mean monthly densities ofA. hydrophila were positively correlated with the incidence of infection in largemouth bass. Largemouth bass from thermally altered parts of the reservoir had a significantly higher incidence of infection. It is concluded that thermal effluent significantly affects the ecology ofA. hydrophila and the epizootiology of red-sore disease within Par Pond.     

Characterization of surface alloantigens of murine neutrophils

Serological analysis of highly purified (>97%) mouse peritoneal exudate neutrophils using a protein-A rosetting technique, showed that these cells possessed the surface phenotype: Ig^–, Thy-1^–, Ly-1^–, Ly-2^–, Ly-3^–, Ly-4⁺, Ly-5⁺, Ly-6⁺, Ly-7^–, Ia^–, FcR⁺ and C3R⁺.