Kinetics of tert-[35S]Butylbicyclophosphorothionate Binding in the Cerebral Cortex of Newborn and Adult Rats: Effects of GABA and Receptor Desensitization

Abstract: The effects of GABA on the kinetics of tert -[³⁵S]butylbicyclophosphorothionate ([³⁵S]TBPS) binding to the convulsant site of GABA_A receptors were studied in membrane suspensions from the cerebral cortex of newborn (1-day-old) and adult (90-day-old) rats. TBPS dissociation was biphasic in neonates and adults, indicating that more than one interconvertible state of [³⁵S]TBPS binding sites may be present in the cerebral cortex. In the absence of GABA, the fast ( t _1/2, 11 min) and slow ( t _1/2, 77 min) components of TBPS dissociation in newborn rats were approximately fourfold slower than in adults. The acceleration of the dissociation rates caused by 2 µ M GABA, however, was more robust in neonates than in adults (six- to ninefold vs. twofold increase, respectively). Moreover, the dissociation rates of TBPS in membranes preincubated with 2 µ M GABA (dissociation started by adding 40 µ M picrotoxin) were two- to fourfold slower than in membranes preincubated without GABA (dissociation started by adding 40 µ M picrotoxin plus 2 µ M GABA). Taken together, these results suggest that (1) the closed state of GABA_A receptors is associated with a more effective steric barrier for the binding of TBPS in neonates compared with adults, (2) GABA produces a larger acceleration of the binding kinetics of TBPS in neonates than in adults, and (3) long incubations with GABA may cause receptor desensitization, which in turn slows down the dissociation rates of TBPS.     

Virtual resource development in the glycosciences

The development of Internet-based virtual resources is a relatively new area of scientific and technical activity that is currently undergoing rapid expansion. Major factors fuelling recent growth include the emergence of multimedia capabilities through the rapid evolution of the World Wide Web, the reduction in cost of high quality personal computers and graphics workstations and the provision of mass-marketed provider services. Prior to 1995 the presence of Internet resources in the glycosciences was virtually non-existent. Existing scientific knowledge was primarily made available on the Net through the provision of databases from gopher and ftp sites. A particular example in the glycosciences is the Carbbank database of biological carbohydrate sequences. We will describe here our efforts in 1994–95 in establishing The Glycoscience Network (TGN, http://bellatrix.pcl.ox.ac.uk/TGN/). These activities included the establishment of a newsgroup, mailing lists, Web resources and the running of the First Electronic Glycoscience Conference (EGC-1, http://bellatrix.pcl.ox.ac.uk/egc/). EGC-1 included many novel initiatives in the glycosciences including electronic posters and papers, a Virtual Conference Centre, a Web-based hyperglossary, Virtual Trade and Employment Centres, refereed electronic publishing, and the creation of a Virtual Reality Gallery. We would like to look towards the near future and discuss several initiatives in virtual resource creation that we believe will have significant scientific impact on the glycosciences including the development of bioinformatics-based servers, sophisticated interactive databases, and videoconferencing. Furthermore, we cherish the belief that these resources will foster international scientific collaboration and progress of an extent never previously possible. Finally, we indulge in speculation and make some suggestions on the form and long-term impact of Glycoscience Virtual Resources. We predict that their development may completely reconstruct the scientific environment that we work in as scientists and we reflect on the probable benefits and pitfalls to be encountered.This paper was presented at the First Electronic Glycoscience Conference (EGCI) on the World Wide Web, September 1995.     

Diurnal variation of corticotropin-releasing factor binding sites in the rat brain and pituitary

Summary 1. Corticotropin-releasing factor (CRF) is thought to be involved in the regulation of the diurnal activity of the hypothalamus-pituitary-adrenal (HPA) axis and to act as a neurotransmitter in the brain. To date it is unknown whether the binding sites of the central CRF system are subject to diurnal variations. 2. We measured the number of CRF binding sites over the course of a complete 24-hr light-dark cycle in the pituitary, amygdala, bed nucleus of the stria terminalis (BNST), cingulate cortex, visceral cortex, paraventricular nucleus of the hypothalamus, hippocampus, and locus ceruleus of rats byin vitro receptor autoradiography with iodinated ovine CRF. A 24-hr time course was also established for plasma CRF and corticosterone. 3. The diurnal pattern of plasma CRF does not correlate with the pattern of plasma corticosterone. Within the brain, CRF binding in the basolateral nucleus of the amygdala showed a U-shaped curve with maximum levels in the morning and a wide hallow between 1500 and 0100. A biphasic profile with a small depression in the afternoon and a more pronounced depression in the second half of the activity period is characteristic for the other brain areas and the pituitary. The profile for the pituitary correlates with those for the BNST and the area of the locus ceruleus. Furthermore, the diurnal pattern of CRF binding sites in the BNST correlates with that of the hippocampus, and the daytime pattern of the visceral cortex is similar to that of both the hippocampus and the BNST. 4. Since the CRF-binding profiles in the brain and the pituitary clearly differ from the profiles of both plasma CRF and corticosterone, one may assume that the diurnal pattern of central CRF binding sites is not directly coupled to the activity of the HPA axis.     

Synthesis of 6-deoxy-5-thio-d-glucose

Three routes were investigated for the conversion of d-glucose into the title compound. In the first approach, reduction of the 5,6-thürane ring of 5,6-dideoxy-5,6-epithio-1,2-O-isopropylidene α-d-glucofuranose (17) as well as that of its 3-O-allyl derivative (13) with lithium aluminium hydride was investigated; 17 afforded the corresponding 6-deoxy derivative besides di-, tri-, and poly-mers, whereas only polymers were formed from 13. In the second approach, the oxirane ring of the MathML source" title="View the MathML source" src="http://binary-services.sciencedirect.com/content/image/1-s2.0-0008621596001437-si1.gif"> was reduced by sodium borohydride and the resulting 6-deoxy derivative was converted into the 5-thiobenzoate; the corresponding hex-4-enofuranose was formed as a byproduct. In the third approach partial mesylation of methyl 5-thio-α-d-glucopyranoside was attempted, but the 6-mesylate 27 could be isolated only in modest yield (28%) together with rearranged 2,5-thioanhydromannofuranoside derivatives. The mechanism of this rearrangement is discussed in detail. The 6-mesylate 27 was converted via the 6-iodo derivative into the title compound.     

A direct comparison of the masculinizing effects of testosterone,androstenedione, estrogen,and progesterone on the development of the zebra finch song system

To assess which hormones are capable of masculinizing the neural song system of zebra finch hatchlings, we implanted female hatchlings with estrogen (estradiol [E2], 75 μg, n = 9), testosterone (T, 75–88 μg, n = 13), androstenedione (AE, 75 μg, n = 7), progesterone (P, 117 μg, n = 10), or nothing (Blanks, n = 10) and compared these to unimplanted males (n = 7). Implants, consisting of a hormone and Silastic mixture encased in polyethylene tubing, were placed under the skin of the breast on the day of hatching. Birds were killed when they were subadult (58 to 68 days old). We measured volumes of area X, the higher vocal center (HVC), and the robust nucleus of the archistriatum (RA); measured soma sizes in the lateral magnocellular nucleus of the neostriatum (IMAN), HVC, and RA: and counted RA neurons. E2 masculinized all measures in the song system and nearly sex-reversed the size of RA neurons. T masculinized volumes of nuclei and soma sizes but not the number or spacing of RA neurons. E2 was always at least as effective as T in masculinizing measures of the song system and was usually more effective. AE and P did not significantly masculinize any measure. These data suggest that E2 is more potent than aromatizable androgens or P in masculinizing the female song system in development and that the action of E2 alone may be sufficient to masculinize the volume of song control nuclei and the size and number of neurons. © 1995 John Wiley & Sons, Inc.     

大豆籽粒蓝脐性状及其分离规律

控制大豆白花亲本籽粒脐色的基因有带Ｒ与ｒ之分,带Ｒ基因的白花产本与紫花亲本杂交,Ｆ１代籽料出现蓝脐性状,其基因型为Ｉ－Ｒ－Ｗ１－ｔｔ。当控制脐色的基因有两对相差时（Ｒ、ｒ;Ｗ１、ｗ１）Ｆ２代籽粒脐色分离蓝脐与无色脐之比为９∶７。     

棉铃虫致病菌BT—931菌株的应用研究

１９９２－１９９３年,作者从菏泽、聊城棉田采集的自然罹病死亡棉铃虫幼虫体内,分离到２个较高毒效的Ｂｔ菌株,编号为ＢＴ—９３１和ＢＴ—０２１,经室内毒力测定和田间药效试验表明,防效及保蕾效果接近或超过化学农药,菌药混剂３—５天平均防治效果达８７．０－９１．６％,增效作用显著。经１９９４年大田防治示范表明,利用ＢＴ—９３１菌剂。配合化学农药防治棉铃虫,具有成本低、保护天敌、持效期长、增产效益高等优点。本研究对菌剂的田间应用技术进行了试验示范。     

东方次睾吸虫电镜研究(吸虫纲:后睾科)V.雌性生殖器官

东方次睾吸虫雌性生殖器官（卵巢、输卵管、卵黄－输卵管、卵模、梅氏腺和子宫）透射电镜 观察。卵巢内有不同成熟期的生殖细胞,成熟初级卵母细胞有几个靠近核的核仁样小聚体和许多沿 质膜的皮质颗粒。首次发现并描述卵巢和输卵管接合处（卵巢壶腹）的超微结构。输卵管上皮为纤 毛状。梅氏腺仅一种类型膜状小体细胞,经有微管支持的细小管道穿过卵模将膜状小体排入卵模腔 内。在卵黄－输卵管和卵模中有精子,卵模和子宫中有受精卵、虫卵（扫描电镜）：大小 ２６. ０５× １１．４６－１３．５５μｍ,卵盖直径６．２６－６. ８９μｐ,卵壳表面布满膜状隆起。文中对卵巢和梅氏腺的超微 结构特点进行了讨论。     

Taxonomy, biology and abundance of icefishes, or noodlefishes (Salangidae), in the Yellow River estuary of the Bohai Sea, China

Four species of icefishes were sampled in the Yellow River estuary of the Bohai Sea from April 1984 to April 1985 and from February 1988 to June 1989. Morphological analysis showed that they belonged to three subfamilies of Salangidae: one species from Protosalangicae, Protosalanx chinensis ; two species from Salanginae, Salanx ariakensis and Salanx prognathus ; and one species, Neosalanx andersoni , from Salangichthyinae, a new subfamily. External morphological characteristics, population composition, growth, maturity, food habits, longevity, fecundity, abundance and distribution of these icefishes are described. Based on these analyses, a clear outline of taxonomy, zoogeography aod biology of icefishes in the Yellow River estuary of the Bohai Sea was established.     

Implications of the variance effective population size on the genetic conservation of monoecious species

The concept of variance effective population size [Ne_(v)] and other expressions are reviewed and described for specific sampling steps in germplasm collection and regeneration of monoecious species. Special attention is given to procedures for computing the variance of the number of contributed gametes [V(k)] to the next generation. Drift, as it occurs between generations, was considered to contain a component due to the sampling of parents and a subsequent component due to the sampling of gametes. This demonstrates that drift, caused by reduction of seed viability, damages the genetic integrity of accessions stored in germplasm banks. The study shows how mating designs, such as plant-to-plant or chain crossings with additional female gametic control, can partially alleviate this problem. Optimal procedures for increasing Ne_(v) when collecting germplasm in the field are also discussed. The effect of different female and male gametic control strategies on Ne_(v) is considered under several situations. Practical examples illustrating the use of V(k) and Ne_(v) expressions are given.