Incipient Speciation by Sexual Isolation in Drosophila Melanogaster: Extensive Genetic Divergence without Reinforcement

The collection of Drosophila melanogaster from Zimbabwe and nearby regions (the Z-type) yield females who would not mate with the cosmopolitan D. melanogaster males (the M-type). To dissect the genetic basis of this sexual isolation, we constructed 16 whole-chromosome substitution lines between two standard Z-and M-lines. The results were as follows: (1) All substitution lines appear normal in viability and fertility in both sexes, indicating no strong postmating isolation. (2) The genes for the behaviors are mapped to all three major chromosomes with the same ranking and comparable magnitude of effects for both sexes: III > II >> X >/= 0 (III, II and X designate the effects of the three chromosomes). The results suggest less evolution on the X than on autosomes at loci of sexual behavior. (3) The genes for ``Z-maleness' are many and somewhat redundant. Whole-chromosome effects for Z-maleness appear nearly additive and show little dominance. (4) In contrast, ``Z-femaleness' has less redundancy as partial genotypes never exhibit full phenotypic effects. Epistatic interactions and incomplete dominance can sometimes be detected. (5) The extensive genetic divergence underlying sexual isolation has evolved in the absence of detectable reduction in hybrid fitnesses. Sexual selection has apparently been a driving force of multiple facets of speciation at the nascent stage without reinforcement.     

The Mammalian Protein (rbet1) Homologous to Yeast Bet1p Is Primarily Associated with the Pre-Golgi Intermediate Compartment and Is Involved in Vesicular Transport from the Endoplasmic Reticulum to the Golgi Apparatus

Yeast Bet1p participates in vesicular transport from the endoplasmic reticulum to the Golgi apparatus and functions as a soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) associated with ER-derived vesicles. A mammalian protein (rbet1) homologous to Bet1p was recently identified, and it was concluded that rbet1 is associated with the Golgi apparatus based on the subcellular localization of transiently expressed epitope-tagged rbet1. In the present study using rabbit antibodies raised against the cytoplasmic domain of rbet1, we found that the majority of rbet1 is not associated with the Golgi apparatus as marked by the Golgi mannosidase II in normal rat kidney cells. Rather, rbet1 is predominantly associated with vesicular spotty structures that concentrate in the peri-Golgi region but are also present throughout the cytoplasm. These structures colocalize with the KDEL receptor and ERGIC-53, which are known to be enriched in the intermediate compartment. When the Golgi apparatus is fragmented by nocodazole treatment, a significant portion of rbet1 is not colocalized with structures marked by Golgi mannosidase II or the KDEL receptor. Association of rbet1 in cytoplasmic spotty structures is apparently not altered by preincubation of cells at 15°C. However, upon warming up from 15 to 37°C, rbet1 concentrates into the peri-Golgi region. Furthermore, rbet1 colocalizes with vesicular stomatitis virus G-protein en route from the ER to the Golgi. Antibodies against rbet1 inhibit in vitro transport of G-protein from the ER to the Golgi apparatus in a dose-dependent manner. This inhibition can be neutralized by preincubation of antibodies with recombinant rbet1. EGTA is known to inhibit ER-Golgi transport at a stage after vesicle docking but before the actual fusion event. Antibodies against rbet1 inhibit ER-Golgi transport only when they are added before the EGTA-sensitive stage. These results suggest that rbet1 may be involved in the docking process of ER- derived vesicles with the cis-Golgi membrane.     

Physiologic regulation of mixtalol in rape senescence and its yield effects

Physiologic and yield effects of mixtalol at various concentrations sprayed on rape at the anthesis stage were examined. Foliar sprays of 4 and 2 ppm mixtalol significantly increased the chlorophyll content of rape leaves and pods, reduced the accumulation of malondialdehyde and ethylene production, and delayed the degradation of superoxide dismutase and catalase activities of the rape plant. Mixtalol also increased root oxidizability. Meanwhile, the number of branches and pods per plant was increased, and a 10.7% and 8.2% increase of seed yield over the controls was observed with treatments of 4 and 2 ppm mixtalol, respectively. No significant effects from mixtalol were observed on the maturation of plants or on the seed oil content or the erucic acid and glucosinolate content. Total rape oil production increased with 4 and 2 ppm mixtalol significantly by 12.4% and 10.5%, respectively, over the controls.Abbreviations MTL mixtalol - MDA malondialdehyde - TBA thiobarbituric acid - SOD Superoxide dismutase - CAT catalase - TTC tetrazolium     

南岭植物区系地理学研究──Ⅲ．植物区系地理亲缘与区划

南岭山地与相邻地区植物区系具有明显的过渡或替代关系,主要通过亚热带及亚热带亚热带亚洲分布成分与华南南亚热带及亚洲热带地区联系;与华中和华东地区植物区系的联系以亚热带及亚热带至温带分布和中国—日本间断分布成分来沟通;与西南地区植物区系的联系则表现为两地共有的古老和与遗成分区及石灰岩山地区系成分．华夏植物区系,是从古老的华夏植物群逐步发展起来的统一体,在区系分区上应划归为统一的华夏植物界,下分东亚植物区、马来西亚植物区和印度—喜马拉雅植物区。南岭山地植物区系拥有其自身的标志种、特有属和丰富的特有种,在区系分区上可划为完整的南岭植物亚省,下分东南岭植物县、中南岭植物县和西南岭植物县。     

三尖杉叶精油化学成分的研究

三尖杉叶精油化学成分的研究苏应娟,王艇,张宏达（中国科学院武汉植物研究所武汉４３００７４）（中山大学生命科学学院广州５１０２７５）关键词三尖杉,精油,化学分类ＡＳＴＵＤＹＯＮＣＨＥＭＩＣＡＬＣＯＮＳＴＩＴＵＥＮＴＳＯＦＥＳＳＥＮＴＩＡＬＯＩＬＦＲＯＭ...     

镁离子对阿霉素线粒体毒性的防护作用

利用ＥＳＲ技术研究了阿霉素与心肌线粒体的相互作用及Ｍｇ＾２＋的防护作用。结果表明：在线粒体及亚线粒体体系,Ｍｇ＾２＋可有效地抑制阿霉素半醌自由基产生,在一定浓度范围内抑制效果依赖于Ｍｇ＾２＋的浓度。另外,Ｍｇ＾２＋显著抑制阿霉素诱导产生的线粒体脂质过氧化。在亚线粒体体系,我们观察到阿霉素半醌自由基的固定化信号,并发现Ｍｇ＾２＋能明显延缓固定化信号出现。     

Effects of prostaglandin E2, 16,16-dimethyl prostaglandin E2 and a prostaglandin endoperoxide analogue (U-46619) on gastric secretory volume, [H] and mucus synthesis and secretion in the rat

The effects of orally administered prostaglandin E₂, 16,16-dimethyl prostaglandin E₂ and U-46619, an analogue of the prostaglandin endoperoxide PGH₂, on gastric secretory volume, acid and mucus were studied in the rat. All of the compounds significantly increased the volume of gastric secretion, mucus secretion, measured as N-acetylneuraminic acid and mucus synthesis measured as the incorporation of [³H]-glucosamine into mucosal glycoprotein; however, only PGE₂ and 16,16-dimethyl PGE₂ inhibited acid secretion. U-46619, 1.5 mg/kg provided significant protection against ethanol-induced gastric ulcers, an effect that has been previously shown for the other two compounds. These studies provide additional evidence that prostaglandin induced mucosal protection may by related to an effect on mucus and on stimulation of nonparietal cell gastric secretion. Further study of these parameters may be important in the development of antiulcer drugs for long term clinical use.     

Functional groups at the catalytic site of F1 adenosine triphosphatase

The protection of F1 ATPase by inorganic phosphate, ADP, ATP, and magnesium ion against inactivation by 1-fluoro-2,4-dinitrobenzene, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, and 1-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline, respectively, has been investigated. Dissociation equilibrium constants and rate constants for the labeling reactions have been deduced from a quantitative treatment of the kinetic data. Comparison of these dissociation constants with each other and with the corresponding literature values indicates that the essential Tyr, Arg, Lys, and Glu or Asp residues are indeed located at the catalytic site of the enzyme. Examination of the rate constants for the labeling reactions in the presence of excess inorganic phosphate, ADP, ATP, or magnesium ion, respectively, suggests that the essential phenol and amino groups are located nearer to the bound inorganic phosphate or the gamma-phosphate group than to the alpha- or beta-phosphate group of the bound ATP, that the essential guanidinium group is located nearer to the alpha- or beta-phosphate group than to the gamma-phosphate group of the bound ATP or the bound inorganic phosphate, and that the essential carboxylate group is located slightly farther away but complexed with magnesium ion which it shares with the bound inorganic phosphate. A mechanism consistent with these topographical relationships is proposed for the catalytic hydrolysis and synthesis of ATP.     

Altered surface glycoproteins in melanoma cell variants with reduced metastasizing capacity selected for resistance to wheat germ agglutinin

Variants of B 16-F 1 mouse melanoma cells selected for resistance to wheat germ agglutinin (WGA) toxicity $\text{in}\text{vitro}$ were found to have undergone a stable surface change correlated both to lectin resistance and reduced metastasizing potential. The surface alteration, as indicated by the increased electrophoretic mobilities of several lactoperoxidase-iodinated cell surface proteins in SDS-PAGE, was restricted to polypeptides able to interact with WGA. The availability of lectin-resistant melanoma cell variants having altered metastasizing behavior provides a promising approach to studies of the role of specific cell surface components in the metastasizing process.