Measurement of the Membrane Potential of Isolated Nerve Terminals by the Lipophilic Cation [3H]Triphenylmethylphosphonium Bromide

Abstract: The lipophilic cation [³H]triphenylrnethylphosphonium bromide ([³H]TPMP⁺) was investigated as a measure of the membrane potential of synaptosomes. Conditions under which [³H]TPMP⁺ achieved an equilibrium distribution were tested. The toxicity of TPMP has been studied relative to its inhibitory effects on [³H]y-aminobutyric acid ([³H]GABA) transport. In some experiments the distribution of ⁸⁶RbZ⁺ and [³H]TPMP⁺ was changed upon incubation in the presence of elevated levels of K⁺, ouabain, or KCN, or at 0°C in a way that would be expected from the membrane potential. In normal incubation conditions a membrane potential of ∼−60 mv was calculated.     

Metabolism of palmitate in cultured rat Sertoli cells

Isolated rat Sertoli cells were incubated in the presence of [1-14C]palmitate at a cell concentration of 1.54 +/- 0.31 mg protein/flask (n = 7). The oxidation of palmitate was concentration dependent and maximal oxidation was obtained at 0.35 mM-palmitate. At a saturating concentration of palmitate the oxidation was linear for at least 6 h. About 65% of the total amount of palmitate oxidized during 5 h at 0.52 mM-palmitate (109 +/- 44 nmol/flask, n = 5) was recovered as CO2 and the rest as acid-soluble compounds. Almost all radioactive acid-soluble compounds which were secreted by the Sertoli cells were shown to be 3-hydroxybutyrate and acetoacetate. The palmitate recovery in cellular lipids and triacylglycerols was 9.4 +/- 5.1 nmol/flask (n = 5) and 3.5 +/- 2.8 nmol/flask (n = 5) respectively. Addition of glucose had no significant effect on palmitate oxidation but caused a 9-fold increase in esterification of palmitate into triacylglycerols. We conclude that cultured rat Sertoli cells can oxidize palmitate to CO2 and ketone bodies and that fatty acids appear to be a major energy substrate for these cells.     

福建冬青属二新种

本文描述了发现于福建的冬青科冬青属2新种——泰宁冬青Ilex tainingensis G. S. He和南平冬青I. nanpingensis G. S. He，并分别说明两者与其他近缘种的区别要点。泰宁冬青与太平山冬青I. sugerokii Maxim.的区别在于前种小枝被毛，无棱槽，叶片宽卵圆形，花淡紫色，分核表面具细条纹，背后中部有一凹槽。南平冬青与拟榕叶冬青I. subficoidea S. Y. Hu区别在于前种果为椭圆形，较大，表面光滑无腺点，果梗长于1 cm，每分核上端有2尖角，均可以区别。     

重庆市生态风险预警等级划分及演化趋势模拟

生态风险预警等级评估和演化趋势模拟，可为生态风险管理提供可靠的辅助决策。以重庆市为研究对象，基于驱动力-压力-状态-影响-响应模型，构建重庆市生态风险预警指标体系，采用正态云模型和集对分析法，定量分析重庆市生态风险时空分异特征和演化趋势。研究结果表明：（1）2013-2019年，重庆市生态风险值呈"上升-下降"的波动趋势，综合生态风险隶属于重警等级，生态风险综合值从0.295下降到0.278，生态环境逐年好转；（2）重庆市生态风险有下降、不变、先上升后降低、先降低后上升以及一直升高5种演化趋势，分别占比39%、16%、5%、21%、24%；（3）重庆市生态风险转移分为两个方向，2013-2016年生态风险空间分异性增大，中警、轻警和无警风险等级不断向东北、东南和西部四周分散转移；2016-2019年生态风险分布格局变化较小，重警风险区在东部聚集；（4）演化趋势模拟结果表明，未来重庆市生态风险降低的区县有13个，占比34%，生态环境有向好发展的趋势；生态风险上升的区县有25个，占比66%，生态环境会有所恶化，但是恶化程度较低。将生态风险等级划分与预警演化趋势相结合，能为城市生态风险管理提供科学依据。     

Effects of cultivation techniques and media on yields and morphology of the basidiomycete Armillaria mellea

Summary The yield of cell mass and the morphology of Armillaria mellea, strain ATCC 11114, was studied using a variety of cultivation methods: solid media, standing liquid culture, shake flasks, tower reactors and impeller-stirred reactors. Two different media, malt extract broth and a glucose/asparagine/peptone-medium, and the corresponding agar media, were used. Yields were higher in the malt extract media than in the glucose media. Generally the highest yields were obtained on solid media while agitated cultures gave the lowest yields. Morphological characteristics such as pellet formation, adhesion to surfaces and pigment production were significantly affected by culture conditions.     

Effects of lactation and removal of pups on the rate of triacyglycerol/fatty acid substrate cycling in white adipose tissue of the rat.

The rate of the triacylglycerol/fatty acid substrate cycle was measured in vivo in adipose tissue of virgin and lactating rats with pups removed. The rate decreased by 70% in adipose tissue of lactating rats and increased 9-fold on removal of the pups. Similar differences in cycling rate were seen in adipose tissue incubated in vitro in the presence of isoprenaline.     

白纹伊蚊幼虫龄期的发育历期

在实验室内20±1℃, 23±1℃, 25±1℃, 28±1℃和30±1℃恒温条件下, 观察了白纹伊蚊(Aedes albopictus)幼虫(广州株)的发育历期.幼虫的总发育历期和各龄幼虫的发育历期随温度的上升而缩短, 各龄幼虫历期在总发育历期中占有恒定的百分比, 据此计算出其捕获机率.各龄幼虫的发育历期与温度呈直线回归关系.通过积温公式, 求出各龄幼虫的积温常数.此外还探索了营养对幼虫发育历期的影响, 从而影响各龄幼虫捕获机率的计算.     

Molecular cloning, cDNA structure and deduced amino acid sequence for a type I regulatory subunit of cAMP-dependent protein kinase from human testis

A 1.5 kilobase (kb) cDNA clone containing the entire coding region for a regulatory subunit of type I cAMP-dependent protein kinase (RI) was isolated from a human testis cDNA library. The cDNA clone encodes a protein of 381 amino acids that shows 98% and 97% homology to the bovine skeletal muscle RI and rat brain RI, respectively. Northern blot analysis demonstrates two major mRNA-species (1.5 and 3.0 kb) in human testis and one mRNA-species (3.0 kb) in human T-lymphocytes.     

Cellular localization and age-dependent changes in mRNA for cyclic adenosine 3',5'-monophosphate-dependent protein kinases in rat testis

Gonadotropin activation of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinases plays an important role in the regulation of testicular function. This study was undertaken to establish the expression of various subunits of cAMP-dependent protein kinases in different testicular cell types as well as during sexual maturation. RNA was extracted from cultured Sertoli cells, cultured peritubular cells, germ cells (pachytene spermatocytes, round spermatids), tumor Leydig cells, as well as whole testis from rats of various ages. Messenger RNA levels were studied by Northern analysis using available cDNA probes. The regulatory subunit (R) designated RII51 was found to be predominantly expressed in cAMP-stimulated Sertoli cells and tumor Leydig cells. Much lower levels were found in cultured peritubular cells and germ cells. A 2.9- and 3.2-kb mRNA for the RI subunit were found at about similar levels in all cell types, whereas the smaller 1.7-kb mRNA was expressed in high levels in germ cells. Also, the catalytic subunit (C) of cAMP-dependent protein kinase, designated C alpha, was expressed in all cell types; the highest mRNA levels for this subunit were found in germ cells and in tumor Leydig cells. The 1.7-kb mRNA for androgen-binding protein (ABP) was abundant in cAMP-stimulated Sertoli cells and was not present in other cell types of the testis. Furthermore, the cellular localization of the cAMP-dependent protein kinase subunits was also supported by developmental studies. The mRNA level of the RII51 3.2-kb species was relatively constant until Day 30, after which there was a tendency to decrease. A 1.6-kb message first appeared at greater ages. The mRNA for the smaller 1.7-kb species of RI, as well as the C alpha, showed a significant increase during development, supporting an enrichment of these mRNAs in germ cells. Messenger RNA levels for ABP were not detected in testis from 5- to 10-day-old rats but increased up to Day 30. After this age, mRNA for ABP revealed an age-dependent decrease, which parallels the relative increase of germ cells in the testis. In summary, these results demonstrate a clear pattern of cellular localization of the various mRNA species for subunits of the cAMP-dependent protein kinase in the rat testis.