Dual action of hydroxylated diphenylethylene estrogens on protein kinase C1

Protein kinase C (PKC) I (gamma), II (beta) and III (alpha) subspecies are all activated by 1,1-di-(p-hydroxyphenyl)ethylene derivatives (DPE) at micromolar concentrations. This PKC activation depends on the presence of both Ca2+ and phosphatidylserine (PS) but does not require diacylglycerol (DG). DPEs enhance PKC activity at low PS concentrations, but not at saturating PS concentrations. Like DG, DPEs increase the apparent affinity of PKC for PS as well as for Ca2+, but lead to a decrease in the catalytic activity (Vmax). In the presence of saturating DG concentrations, DPEs exhibit an inhibitory action. The derivatives also inhibit the activity of the proteolytic fragment of PKC, protein kinase M. It is concluded that DPEs are mixed-type inhibitors, probably interacting with the catalytic domain of the enzyme.     

Prenatal development of monoamine neurons in the rat]

The histofluorescence method allows the study of the prenatal development of monoamines neurons in the foetal rat brain. Certain patterns of this development can be defined: the locus niger and the raphe appears fluorescent on the 14th day, the locus coeruleus on the 15th day. These systems differentiate independently in various areas of the neural axis. Their maturation are progressive: first for the DA system, then for the NA and the 5 HT systems. The mechanisms for synthesis and storage of amines precede the complete development of the effector structures.     

Significance of temperature fluctuation and oxygen concentration for germination of the rice field weeds Fimbristylis littoralis and Scirpus juncoides

Summary A diurnally fluctuating temperature was found to be almost an absolute requirement for the germination of Fimbristylis littoralis and Scirpus juncoides. It is demonstrated that in f. littoralis sensitivity to the amplitude of temperature fluctuation can functuation as a depth sensing mechanism under water. This species did not germinate at all in the absence of oxygen. S. juncoides germinated best in anaerobic conditions and at low oxygen concentrations, but normal atmospheric concentrations inhibited germination. It is shown that this requirement for little or no oxygen together with the requirement for a fluctuating temperature cause the germination of S. juncoides to be restricted to the upper layers of waterlogged soil.     

Metabolism of glycerate-2,3-P2--II. Enzymes involved in the glycerate-2,3-P2 metabolism in chicken skeletal muscle

1. Four enzyme fractions which may be involved in the synthesis and breakdown of glycerate-2,3-P2 have been isolated from extracted skeletal muscle by gel-filtration and ion-exchange chromatography. 2. One of the fractions, corresponding to the glycerate-2,3-P2 dependent phosphoglycerate mutase, has been purified to homogeneity. In addition to the main enzymatic activity, it shows intrinsic glycerate-2,3-P2 synthase activity and glycerate-2,3-P2 phosphatase activity stimulable by glycolate-2-P. Its synthase activity represents about 10% of the total synthase activity of the tissue, and its phosphatase activity corresponds to about 60% of the total phosphatase activity. 3. Two of the fractions have glycerate-2,3-P2 synthase, glycerate-2,3-P2 phosphatase and phosphoglycerate mutase activities in a ratio similar to that of the glycerate-2,3-P2 synthase described in mammalian skeletal muscle. Their synthase activity corresponds to about 90% of the total synthase activity, and their phosphatase activity represents about 1% of the total phosphatase activity of the tissue. 4. The fourth fraction shows only glycerate-2,3-P2 phosphatase activity and represents about 40% of the total activity of the tissue. 5. It is suggested that in chicken skeletal muscle the metabolism of the glycerate-2,3-P2 is regulated in a way similar to that described in mammalian skeletal muscle.     

Formation of pure and mixed clones of c mutants in serratiaphage sigma after treatment of the free virion with UV or hydroxylamine

The clone composition of c mutants of phage σ induced by UV irradiation of the free virion was studied, using Hcr⁺, Hcr^? and UV-irradiated Hcr⁺ cells as hosts and 2, 3 and 4 different UV doses, respectively. Most of the c plaques contained only mutant phages, and the distribution of mosaics was asymmetrical, i.e. most mixed clones contained >80% mutant type. The frequency of mosaics decreased with increasing UV dose in all three host systems; however, the decrease was significant only with the UV-irradiated Hcr⁺ host. Propagation of UV-irradiated σ in Hcr⁺ and Hcr^? hosts, respectively, did not lead to a significant difference in the frequency of mosaics, but, using UV-irradiated Hcr⁺ host significantly increased the percentage of mixed clones.The composition of plaques containing c mutants, after UV irradiation and treatment with hydroxylamine, was also studied by picking and testing all plaques (mutant and wild-type) of the survivors of a single UV dose and a single incubation time, respectively. In both experiments, besides pure and nearly pure (visible) c mutant plaques, many cryptic mutants containing predominantly >20% mutant type were found. The distribution of mosaics was of an almost “inverse symmetrical” type, the class of clones with about 50% mutant and 50% wild-type being the rarest.From these results incomplete recombinational repair is suggested to be responsible for the formation of pure mutant clones in mutation induction.