Putative candidate genes for blood pressure control in the SHR.BN-RNO8 congenic substrains

The SHR-Lx congenic strain carrying a differential segment of chromosome 8 of BN and PD origin was recently shown to exhibit a significant decrease in blood pressure as compared to the SHR strain. There were two positional candidate genes for blood pressure control mapped to the differential segment: the rat kidney epithelial potassium channel gene (Kcnj1) and brain dopamine receptor 2 gene (Drd2). Bot these genes were separated into SHR.BN-RNO8 congenic substrains. In this communication, we are presenting the assignment of two further putative candidate genes, which might be involved in blood pressure control to the BN/PD differential segment of the SHR-Lx congenic strain. These are: the gene coding for smooth muscle cell specific protein 22 (Sm22) defined by the D8Mcw1 marker and neuronal nicotinic acetylcholine receptor gene cluster, defined by the D8Bord1 marker. Moreover, the glutamate receptor gene Grik4 which also maps to the differential segment of the SHR-Lx should be taken into account. The genetic separation of all these putative candidate genes of blood pressure control is being performed by recombinations and subsequent selection using (SHR×SHR-Lx) intercross population.     

Sodium-Dependent Proline Uptake in the Rat Hippocampal Formation: Association with Ipsilateral-Commissural Projections of CA3 Pyramidal

Na+-dependent uptake of L-[3H]proline was measured in a crude synaptosomal preparation from the entire rat hippocampal formation or from isolated hippocampal regions. Among hippocampal regions, Na+-dependent proline uptake was significantly greater in areas CA1 and CA2-CA3-CA4 than in the fascia dentata, whereas there was no marked regional difference in the distribution of Na+-dependent gamma-[14C]aminobutyric acid ([14C]GABA) uptake. A bilateral kainic acid lesion, which destroyed most of the CA3 hippocampal pyramidal cells, reduced Na+-dependent proline uptake by an average of 41% in area CA1 and 52% in area CA2-CA3-CA4, without affecting the Na+-dependent uptake of GABA. In the fascia dentata, neither proline nor GABA uptake was significantly altered. Kinetic studies suggested that hippocampal synaptosomes take up proline by both a high-affinity (KT = 6.7 microM) and a low-affinity (KT = 290 microM) Na+-dependent process, whereas L-[14C]glutamate is taken up predominantly by a high-affinity (KT = 6.1 microM) process. A bilateral kainic acid lesion reduced the Vmax of high-affinity proline uptake by an average of 72%, the Vmax of low-affinity proline uptake by 44%, and the Vmax of high affinity glutamate uptake by 43%, without significantly changing the affinity of the transport carriers for substrate. Ipsilateral-commissural projections of CA3 hippocampal pyramidal cells appear to possess nearly as great a capacity for taking up proline as for taking up glutamate, a probable transmitter of these pathways. Therefore proline may play an important role in transmission at synapses made by the CA3-derived Schaffer collateral, commissural, and ipsilateral associational fibers.     

Maturation of locust corpora allata during the reproductive cycle: Effect of reserpine on allatotropic activity,juvenile hormone-III biosynthesis,and oocyte development

Reserpine, at doses of 20–175 μg per g body weight, severely retards oogenesis in newly emerged adult female migratory locusts (Locusta migratoria migratorioides) but does not increase mortality during the first 9 days and only slightly delays somatic growth. Total protein, and hemolymph vitellogenin content particularly, are significantly reduced in reserpine-treated locusts. The synthesis of juvenile hormone III (JH-III) following adult emergence, essential for induction of vitellogenesis and subsequent oogenesis, is dependent on the maturation and activation of the corpora allata (CA). CA of 7- to 8-day-old female locusts, treated with reserpine at day 1 after adult emergence, are only marginally active in vitro and are only slightly stimulated by an allatotropic factor. The basal activity and response of CA from the reserpine-treated locusts resembles that of newly emerged locusts, suggesting that reserpine specifically retards the initial maturation of the locust CA. Recovery of basal CA activity is evident on days 12–13 in reserpine-treated locusts, but responsiveness to the allatotropic factor is not recovered. Starvation of newly emerged females for 3 days and subsequent feeding did not effect ooctye development or CA activity. Cerebral content of the allatotropic factor, assayed on days 7–8, is not reduced by the reserpine treatment.     

Partial purification and characterization of locust allatotropin I

Methanol extracts of locust brains, corpora cardiaca (CC), and suboesophageal ganglia (SOG) were separated by gradient and/or isocratic reverse-phase high-performance liquid chromatography (HPLC) and allatotropic activity monitored in the eluted fractions. A major peak of activity, separated by isocratic separation with 12% 2-propanol, designated allatotropin I, exhibited identical retention times in the three tissue extracts. Doseresponse curves of allatotropin I indicate similar content in brain and CC-equivalents, whereas optic lobes, similarly separated by isocratic HPLC, contain only one-tenth of this amount of allatotropin. Allatotropin I is resistant to boiling and is susceptible to tryptic and chymotryptic digestion. Methanol extracts of thoracic muscle, Malpighian tubules, fat body or ovaries, similarly prepared and boiled, did not exhibit allatotropic activity at high doses of tissue equivalents.     

Formamidines interact withDrosophila octopamine receptors,alter the flies' behavior and reduce their learning ability

Summary We have studied the effect of formamidines onDrosophila melanogaster. Low concentrations of formamidines are toxic to adultDrosophila. A mutant with reduced cAMP synthesis displays increased resistance to the toxin. Formamidines also reduce viability ofDrosophila eggs and retard imago eclosion. At sublethal concentrations, formamidines markedly affect the flies' behavior. Upon injection, the compounds increase muscle activity. Upon feeding, formamidines induce motor excitation, reduce phototaxis and impair olfactory learning without affecting the ability to recognize an olfactory cue. In vitro, two formamidines were found to inhibit octopamine-stimulated adenylate cyclase without affecting the basal activity of the enzyme, while a third one was found to stimulate adenylate cyclase; this stimulation was blocked by phentolamine and to a lesser degree by propranolol, thus resembling the effect of octopamine. The binding of [³H]octopamine toDrosophila head membranes was also inhibited. Taken together, our results indicate that formamidines interact with octopaminergic systems inDrosophila, exert both peripheral and central effects in the fly, and could be used to dissect the roles of octopamine in development and behavior, including behavioral plasticity. The results also suggest that formamidines could be used to select mutants in aminergic transmission and in the cAMP cascade.Abbreviations CDMF chlordimeform - DMPF N,N-dimethyl-N2-(2,4-dimethylphenyl) formamidine     

Genetic differentiation and biochemical polymorphism among trichomonads

Isoenzyme electrophoresis was used to study levels of genetic differentiation among strains and clones of Trichomonas gallinae, Trichomonas vaginalis, Tritrichomonas foetus, Tetratrichomonas gallinarum, and Pentatrichomonas hominis. Strain variation was found within T. gallinae, T. vaginalis, and T. foetus, however, levels of enzyme polymorphism were greater in T. gallinae than in T. vaginalis or T. foetus. Isoenzyme genotypes were not a stable property of T. gallinae clones cultivated in vitro. Retrospective studies of T. gallinae SG and JB6 clones revealed that mutation occurred during in vitro cultivation. Heterozygotes of hexokinase-1 and phosphoglucomutase displayed 2 allomorphs in equal dosage, indicating that trichomonads are diploid for these protein loci. Phenetic clustering of the biochemical data suggests that levels of genetic divergence among the species studied are extensive.