Intracerebroventricular infusion of neuropeptide Y up-regulates synthesis and accumulation of luteinizing hormone but not follicle stimulating hormone in the pituitary cells of prepubertal female lambs

Neuropeptide Y (NPY) is a putative neuroregulator of the reproductive axis in the central nervous system. In this study we evaluated the effects of central infusion of exogenous NPY on the secretory activity of pituitary gonadotrophic cells in prepubertal lambs. Immature female Merino sheep (n=12) were infused of Ringer solution (control) or 50 microg of NPY to the third ventricle for 5 min and then slaughtered 3 h later. Immunoreactive luteinizing hormone (LH) and follicle stimulating hormone (FSH) cells were localised by immunohistochemistry using antibody raised against LHbeta and FSHbeta. Messenger RNA analyses were performed by in situ hybridisation using sense and antisense riboprobes produced from beta subunits of LH and FSH cDNA clones. The results were generated by computer image analysis to determine the area fraction occupied by immunoreactive and/or hybridising cells and optical density for immunostaining and hybridisation signal. LH in the blood plasma was determined by radioimmunoassay. It was found, that in the lambs infused with NPY the area fraction and optical density for immunoreactive LH cells and mRNA LHbeta-expressing cells increased significantly (P<0.001), compared to the vehicle-infused animals. The concentration of LH in the blood plasma did not differ between control and treated groups. The NPY infusions had no effect on the immunoreactivity of FSH cells or on expression of mRNA for FSHbeta. In conclusion we suggest that NPY may be an important component of mechanisms stimulating the synthesis and storage but not the release of LH in the pituitary gonadotrophs from prepubertal female sheep. In addition, this effect is specific for LH, no such effect was apparent on FSH.     

Factors that affect genetic interaction during mixed infection with temperature-sensitive mutants of simian rotavirus SA11

A number of factors that affect genetic interaction during mixed infection with temperature-sensitive mutants of simian rotavirus SA11 have been examined. (1) Statistical analyses of recombination frequency (RF) indicated that (a) the variability noted in RF was not related to variations in experimental conditions and (b) a linear map of the mutations could not be drawn. (2) The wild phenotype of recombinant progeny was stable on passage. (3) Aggregates of progeny virus or heterozygous progeny virus particles did not contribute significantly to the observed RF. (4) RF increased in parallel with multiplicity of infection. (5) A maximal, or near maximal, RF was obtained at the earliest time significant recombinants could be detected. (6) Recombination was efficient at nonpermissive temperature. (7) Complementation did not occur or was inefficient. (8) Mutants from all recombination groups interfered with the growth of wild-type virus at both permissive and nonpermissive temperatures.     

Occurrence of neuropeptide Y (NPY)-like immunoreactivity in catecholamine neurons in the human medulla oblongata

We report here the coexistence of a neuropeptide and catecholamines in neurons of the human brain. Using indirect immunofluorescence histochemistry, combined with elution and restaining experiments, neurons in the medulla oblongata of man were demonstrated to contain both a neuropeptide Y-like peptide and the catecholamine synthesizing enzyme tyrosine hydroxylase.     

Is there an effect of monocular deprivation on the proportions of X and Y cells in the cat lateral geniculate nucleus?

Summary The proportions and receptive field properties of X and Y cells in the A and A1 layers of the lateral geniculate nucleus (LGN) were studied in monocularly deprived cats. Contrary to previous reports, we found that there was no change in the relative number of Y cells in the geniculate layers driven by the deprived eye. There was also no marked change in the spatial resolution of X or Y cells driven from the deprived eye as compared to the cells driven from the normally experienced eye. In these same cats, the visual evoked potential from stimulation of the deprived eye with grating patterns was markedly reduced in amplitude. Furthermore, the cell bodies of the cells in the LGN driven by the deprived eye had shrunk. Therefore, these usual consequences of monocular deprivation are not necessarily associated with a loss of geniculate Y cells.     

Complex evolution of X and Y autosomal translocations in the giant mole-rat, Cryptomys mechowi (Bathyergidae)

Cross-species chromosome painting was used to determine homologous chromosomal regions between two species of mole-rat, the naked mole-rat, Heterocephalus glaber (2n = 60), and the giant mole-rat, Cryptomys mechowi (2n = 40), using flow-sorted painting probes representative of all but two of the H. glaber chromosomal complement. In total 43 homologous regions were identified in the C. mechowi genome. Eight H. glaber chromosomes are retained in toto in C. mechowi, and 13 produce two or more signals in this species. The most striking difference in the karyotypes of the two taxa concerns their sex chromosomes. The H. glaber painting probes identified a complex series of translocations that involved the fractionation of four autosomes and the subsequent translocation of segments to the sex chromosomes and to autosomal partners in the C. mechowi genome. An intercalary heterochromatic block (IHB) was detected in sex chromosomes of C. mechowi at the boundary with the translocated autosomal segment. We discuss the likely sequence of evolutionary events that has led to the contemporary composition of the C. mechowi sex chromosomes, and consider these in the light of prevailing views on the genesis of sex chromosomes in mammals.     

In situ fluorescence hybridization of Y translations: cytogenetic analysis using probes Y190 and Y431

Two moderately repetitive DNA probes (Y190 and Y431) and a fluorescent in situ hybridization technique, using a biotin, avidin, anti-avidin system, were employed to investigate a group of patients with Y chromosome abnormalities. In normal male subjects, a bright fluorescent spot could be detected in cells in interphase and on the short arm of the Y chromosome in metaphase spreads. Translocations of DNA fragments of the short arm of the Y chromosome to autosomes 10, 13 and 15 were observed in five patients. In a 45,XX male subject the translocation involved one of the X chromosomes. With this in situ hybridization procedure, bright fluorescent spots were also noticed in uncultured amniotic cells and chorionic cellular elements from male fetuses, thus allowing a rapid and reproducible approach to prenatal fetal sexing.     

河北汉族人群四个Y短串联重复序列基因座遗传多态性

目的调查Y染色体特异基因座DYS438、DYS439、GATAA7.1、GATAA7.2的遗传多态性在河北汉族人群中的分布。方法应用聚合酶链反应及8%变性聚丙烯酰胺凝胶电泳分离扩增产物结合银染显带技术,对DYS438、DYS439、GATAA7.1、GATAA7.2基因座进行调查。结果DYS438、DYS439、GATAA7.1、GATAA7.2基因座分别检出4、5、5、4种等位基因,基因频率分布分别为0.0359～0.6587、0.0179～0.4107、0.0122～0.4146、0.0476～0.5238,个人识别率分别为0.5121、0.6811、0.6679和0.6327;上述4个基因座组成的单倍型在164名无关男性中共观察到70种,其中有36种仅出现一次,单倍型的个人识别机率达0.9480,家系调查符合单倍型父系遗传方式。结论DYS438、DYS439、GATAA7.1、GATAA7.2基因座个人识别机率高,属较高鉴别能力的遗传标记系统,且具有明显的人群分布差异,在法医学及人类遗传学研究中具有重要的应用价值。     

Mechanisms of the ATP potentiation of hyposmotic taurine release in Swiss 3T3 fibroblasts

Reducing osmolarity by 35% increased ³H-taurine efflux from Swiss 3T3 fibroblasts from 0.5% to a peak of 5.7%. The presence of ATP (10–100 µM; EC₅₀ 1.5 µM) increased taurine efflux up to 10%, and decreased the set point for hyposmotically stimulated taurine release (HTR). ATP potentiation was mimicked by UTP, reduced by addition of suramin and pyridoxal phosphate-6-azophenyl-2,4-disulphonic acid (PPADS) and unaffected by ADP, ,-methylene-ATP (,-ATP) or 2-methylthio-ATP (Me-ATP), suggesting its mediation by purinergic P2Y₂ and P2Y₄ metabotropic receptors. Under isosmotic conditions ATP increased the cytosolic [Ca²⁺] ([Ca²⁺]_i) markedly, but did not increase taurine release. HTR was independent of external Ca²⁺ but was reduced (by 56–59%) by BAPTA-AM, thapsigargin-induced depletion of intracellular Ca²⁺ stores, or phospholipase C (PLC) inhibition. Blockade of calmodulin (CaM) or calmodulin kinase II (CaMKII) reduced HTR by 54% and 76%, respectively. The ATP-mediated potentiation was prevented fully by all these treatments. HTR was reduced by 30–50% by blockers of protein tyrosine kinases (AG18), phosphoinositide 3-kinase (PI3K) (wortmannin), p21rho (toxin B), p21rho-kinase (Y27632) and the stress-activated kinase p38 (PD169316). ATP-mediated potentiation was reduced similarly by these blockers. Simultaneous inhibition of PI3K and CaMKII abolished HTR. Altogether, these results suggest a modulatory effect of ATP, probably exerted by a potentiation of the Ca²⁺-dependent fraction of HTR. This fraction has as signalling elements a PLC-dependent [Ca²⁺]_i increase, resulting from Ca²⁺ released from thapsigargin-sensitive internal stores, followed by activation of CaM/CaMKII reactions. The Ca²⁺/ATP effect operates only when the Ca²⁺-independent, tyrosine kinase-mediated pathway is already activated. Suggested elements of cross-talk between the two pathways are PLC, PI3K and CaMKII.     

Desensitization of acetylcholine induced inositol 1,4,5-trisphosphate formation in neuroblastoma SH-SY5Y cells following repetitive acetylcholine stimulations

In this study, the desensitization of acetylcholine-induced inositol 1,4,5-trisphosphate [I(1,4,5)P₃] formation, upon short-time prestimulations, was investigated in cultures of human neuroblastoma SH-SY5Y cells. Four repeated stimulations for 10 seconds with 10 μM acetylcholine were necessary to induce a desensitization of the I(1,4,5)P₃ formation. The desensitization was observed 4 hours after the initiation of repetitive stimulations. The same effect was obtained by a single prestimulation with 1 mM acetylcholine. Preincubation of the cells with phorbol 12-myristate 13-acetate (PMA) markedly down-regulated the acetylcholine-induced I(1,4,5)P₃ formation. However, the protein kinase C (PKC) inhibitors H7 and staurosporine did not influence the desensitization induced by four repeated stimulations with 20 μM acetylcholine. These results indicate that the signal transduction can be desensitized following repeated stimulations with sub-maximal concentrations of receptor agonist and although activation of PKC can induce the same down-regulation, PKC is most likely not involved in the desensitization induced by repetitive acetylcholine-stimulations.