The effect of serum,EGF, PGF2α and insulin on S6 phosphorylation and the initiation of protein and DNA synthesis

To test the connection between S6 phosphorylation and the activation of protein and DNA synthesis, we compared the effects of serum, epidermal growth factor (EGF), prostaglandin F_2α (PGF_2α) and insulin (which is not mitogenic in these cells). Increasing concentrations of serum or EGF produced roughly parallel effects on all three processes, though the maximum response elicited by EGF (10^?9 M) was only a portion of that caused by saturating levels of serum (7.5% to 10%). PGF_2α (8.5 × 10^?7 M) alone acted similarly to EGF (10^?9 M) and with EGF produced a synergistic effect on all three processes. Insulin (10^?9 M) alone stimulated both S6 phosphorylation and protein synthesis to approximately the same level as EGF or PGF_2α, but had no effect on initiation of DNA synthesis. Thus neither stimulation of S6 phosphorylation nor activation of protein synthesis is sufficient for initiation of DNA synthesis. The requirement for S6 phosphorylation could not be dissociated from the activation of protein synthesis. Ribosomes containing the most highly phosphorylated forms of S6 appear to have a selective advantage in entering polysomes.     

Digoxin-like immunoreactivity of 19-NOR and 19-OH-androst-4-ene-3,17-dione

Digoxin-like immunoreactivity of 19-OH-androst-4-ene-3,17-dione and 19-NOR-androst-4-ene-3,17-dione estimated by radioimmunoassay was by about four orders of magnitude lower than that of digoxin.     

Within-tree spatial variation in the leaf monoterpenes of Sequoia sempervirens

Location within a tree was analyzed as a source of variation in Sequoia sempervirens leaf monoterpenes. No differences were found for quantitative composition or total yield/dry wt among lower, middle and upper canopy positions. The awlshaped, spirally arranged leaves of vigorous upper shoots showed small quantitative compositional differences, but not differences in total yield. The intermediate leaf form of young sprouts had the most different monoterpene quantitative composition and about three times the total yield of the above two leaf forms. Analysis of a clonal ring of 17 adult trees resulted in coefficients of variation similar to those for samples collected from different canopy levels of the same shoot. Results revealed the sources and magnitudes of experimental error in comparative studies of this species' leaf monoterpenes, and did not support the concept that somatic mutation provides an important source of variation in a large, long-lived organism such as coast redwood.     

Block by phencyclidine of acetylcholine and barium induced adrenal catecholamine secretion

Activation of the sympathetic system by phencyclidine (PCP) should result in catecholamine release from the adrenals. However, adrenalectomy does not reduce PCP-induced hypertension. In an attempt to rectify this inconsistency, the direct effects of PCP on the bovine adrenal medulla were examined. At (3×10^?6M), PCP reduced the acetylcholine-(ACh)-induced catecholamine release by 50%. Surprisingly, barium-induced secretion of catecholamines was also reduced by PCP. ACh-induced catecholamine release was not altered by 10^?3M 4-aminopyridine (4 AP), the potassium channel blocker. Thus, calcium antagonist actions of PCP and consequent block of catecholamine secretion from adrenal medulla may explain the lack of effect of adrenalectomy on PCP-induced hypertension. Possible contributions of calcium and/or potassium channel blockade to other manifestations of PCP overdosage are discussed.     

Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) parasitizing terrestrial isopods (Isopoda: Oniscoidea)

Summary A new mermithid nematode, Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) was found parasitizing two terrestrial isopods (Isopoda: Oniscoidea) in California. The hosts, Armadillidium vulgare (Latr.) (a pillbug) and Porcellio scaber (Latr.) (a sowbug) represent the first cases of isopods attacked by mermithid nematodes. The genus Thaumamermis can be distinguished from all previously described mermithids by the extremely dimorphic spicules, one being short and broad and the other long and filiform. It has been discovered that the nematodes are infected with an iridiovirus which commonly destroys the isopod hosts. ac]19800917     

Porphyrogenic effects and induction of heme oxygenase in vivo by δ-aminolevulinic acid

The effects of single large doses of the porphyrin-heme precursor ?d-aminolevulinic acid on tissue porphyrins and on δ-aminolevulinate synthase and heme oxygenase, the rate-living enzymes of liver heme synthesis and degradation respectively, were studied in the chick embryo in ovo, in the mouse and in the rat. δ-Aminolevulinic acid treatment produced a distinctive pattern characterized by extensive tissue porphyrin accumulation and alterations in these rate-limiting enzymes in the liver. Repression of basal or allylisopropylacetamide-induced liver δ-aminolevulinate synthase was observed and, in the mouse and the rat, induction of liver heme oxygenase after δ-aminolevulinic acid treatment, in a manner similar to the known effects of hemin on these enzymes. In the chick embryo liver in ovo heme oxygenase was substantially higher than in rat and mouse liver, and was not significantly induced by δ-aminolevulinic acid or other compounds, including hemin, CS₂ and CoCl₂. Levulinic acid, an analogue of δ-aminolevulinic acid, did not induce heme oxygenase in mouse liver. δ-Aminolevunilic acid treatment did not impair ferrochelatase activity but was associated with slight and variable decreases in liver cytochrome P-450. Treatment of chick embryos with a small ‘priming’ dose of 1,4-dihydro-3,5-dicarbethoxycollidine, which impairs liver ferrochelatase activity, accentuated porphyrin accumulation after δ-aminolevulinic acid in the liver. These observations indicate that exogenous δ-aminolevulinic acid is metabolized to porphyrins in a number of tissues and, at least in the liver, to a physiologically significant amount of heme, thereby producing an increase in the size of one or more of the heme pools that regulate both heme systhesis and degradation. It is also possible than when δ-aminolevulinic acid is markedly overproduced in vivo it may be transported to many tissues and re-enter the heme pathway and alter porphyrin-heme metabolism in cells and tissues other than those in which its overproduction primarily occurs.     

Alkaliphilic anaerobic community at pH 10

Relict or ancient microbial communities in extreme environment might be analogous to the centers of origin of bacterial diversity. A bacterial community of an alkaline lake was investigated, and the diversity of bacteria found there indicates that both conditions of autonomy and phylogenetic variety are fulfilled for anaerobic bacteria developing at pH 10±0.2. Major functional groups in the trophic network were present. Representatives of proteolytic, bacteriolytic, cellulolytic, saccharolytic, dissipotrophic, acetogenic, sulfate-reducing, methanogenic bacteria were isolated.