Mellifluous matures to malodorous in musth

Male Asian elephants in musth--an annual period of heightened sexual activity and intensified aggression--broadcast odoriferous, behaviourally influential messages from secretions of the temporal gland. From our observations in the wild, together with instantaneous chemical sampling and captive-elephant playback experiments, we have discovered that young, socially immature males in musth signal their naivety by releasing honey-like odours to avoid conflict with adult males, whereas older musth males broadcast malodorous combinations to deter young males, facilitating the smooth functioning of male society. As elephant--human conflicts can upset this equilibrium, chemically modulating male behaviour may be one way to help the conservation of wild elephants.     

植物的第二性征

本文综述了雌雄异株植物的第二性征，列举了大量例子证明这种生命现象的客观存在及其在雌雄异株营养体上生长习性、形态特征、生态位、种群中雌雄比率的不同表现。根据植物第二性征的运动规律，可有目的地在种群中雌株和雄株间进行定向选择，控制种群的性比率。     

Testis determination requires insulin receptor family function in mice

In mice, gonads are formed shortly before embryonic day 10.5 by the thickening of the mesonephros and consist of somatic cells and migratory primordial germ cells. The male sex-determining process is set in motion by the sex-determining region of the Y chromosome (Sry), which triggers differentiation of the Sertoli cell lineage. In turn, Sertoli cells function as organizing centres and direct differentiation of the testis. In the absence of Sry expression, neither XX nor XY gonads develop testes, and alterations in Sry expression are often associated with abnormal sexual differentiation. The molecular signalling mechanisms by which Sry specifies the male pathway and models the undifferentiated gonad are unknown. Here we show that the insulin receptor tyrosine kinase family, comprising Ir, Igf1r and Irr, is required for the appearance of male gonads and thus for male sexual differentiation. XY mice that are mutant for all three receptors develop ovaries and show a completely female phenotype. Reduced expression of both Sry and the early testis-specific marker Sox9 indicates that the insulin signalling pathway is required for male sex determination.     

Molecular regulation of sexual preference revealed by genetic studies of 5-HT in the brains of male mice

Although the question of to whom a male directs his mating attempts is a critical one in social interactions, little is known about the molecular and cellular mechanisms controlling mammalian sexual preference. Here we report that the neurotransmitter 5-hydroxytryptamine (5-HT) is required for male sexual preference. Wild-type male mice preferred females over males, but males lacking central serotonergic neurons lost sexual preference although they were not generally defective in olfaction or in pheromone sensing. A role for 5-HT was demonstrated by the phenotype of mice lacking tryptophan hydroxylase 2 (Tph2), which is required for the first step of 5-HT synthesis in the brain. Thirty-five minutes after the injection of the intermediate 5-hydroxytryptophan (5-HTP), which circumvented Tph2 to restore 5-HT to the wild-type level, adult Tph2 knockout mice also preferred females over males. These results indicate that 5-HT and serotonergic neurons in the adult brain regulate mammalian sexual preference.     

雌雄异型异熟植物的开花机制研究进展

雌雄异型异熟是植物从雌雄同花向雌雄异株进化过程中的一种过渡类型,目前发现存在于13个科20个属植物中。其群体中包括雌先型和雄先型两种交配类型,两种交配类型植株的同步性和互不干扰性可有效地避免自交。一般认为雌雄异型异熟植株的交配类型是固定不变的,但也在一些植物中发现了彼此间的转化; 植株内雌雄花开放时间有的完全错开,有的部分重叠。经典遗传学认为交配类型受1对显/隐性的等位基因控制,且当群体达到平衡时两种交配类型的比例可达平衡状态(1:1),这在胡桃属和山核桃属上得到了验证,但在其他同类植物分子生物学方面的研究还是空白。雌雄异型异熟植物的性别决定为饰变型,其性别分化不仅受性别决定基因的遗传控制,而且还受植物激素的诱导调控,但不同植物上激素诱导性别分化的作用存在差异。解剖学研究表明同一交配类型上的雌雄花发育和成熟时间均存在差异。     

分子对接研究手性共价有机框架材料的对映体识别能力

基于分子对接方法,使用AutoDock软件计算手性共价有机框架材料CCOF5与手性对映体相互作用的结合能.计算结果表明:CCOF5与对映体的结合能差大小与对映体分离度大小相一致;CCOF5与对映体的结合能大小与对映体出峰时间顺序基本一致.采用Avogadro软件对AutoDock分子对接构象进行分析,并对手性识别机理进...     

中国林蛙南移养殖雌性诱变技术研究

当前中国林蛙的全人工养殖已经在我国各地兴起,中国林蛙南移养殖技术已取得重大突破,但性别比例失调问题严重,雌蛙和雄蛙的比例只有3:7,严重影响养殖效益,制约养蛙业的发展.为调整林蛙性别比例,分别在实验室内和浙江省新昌县新益生物科技有限公司中国林蛙养殖中心采用控温及在蝌蚪饵料中添加性激素双重调控方法,诱导性腺分化,达到了调整林蛙性别的目的,并对激素诱导的合适浓度和最佳时期进行了研究,使中国林蛙雌雄比例达到7:3.为促进中国林蛙南移养殖的发展提供了切实可行的雌性诱变技术.     

南京地区簸箕柳雌、雄花序建成动态观察

【目的】 柳树雌株性成熟后会产生严重的飞絮污染,阐明其性别分化的分子机制是控制飞絮污染的关键。研究柳树雌、雄花芽分化以及花序建成的关键时期,为性别分化分子调控机理研究奠定基础。【方法】 以木本植物簸箕柳(Salix suchowensis)雌株和雄株花芽及花序为材料,从当年6月至翌年2月分别在17个时间点采集样品,利用石蜡切片技术对其雌、雄花芽分化及花序建成过程进行观察,分析不同发育阶段的相关特征。【结果】 簸箕柳花序建成初期为6月中旬至7月初,小花原基分化期在7月中旬至8月下旬,雌、雄蕊分化期在9月上旬至11月初,11月中旬至翌年2月初雌雄花序进入休眠期,翌年2月中旬至3月为大小孢子发生及雌雄配子体发育期,随后雌雄花序开放。研究表明,花序外观形态变化与内部解剖结构变化之间具有一定的相关性。【结论】 簸箕柳雌、雄花均为单性花。花序生长趋势总体呈“S”形上升趋势,在整个发育过程中,雄花序比雌花序外形稍大。簸箕柳花序外观形态可以用于判断花发育的关键时期。研究结果为全面了解簸箕柳花芽分化以及花序建成的完整过程提供了详细信息,为进一步阐明不同关键发育阶段的分子调控机制奠定了基础。     

Evidence from mosaic analysis of the masculinizing gene her-1 for cell interactions in C. elegans sex determination.

Sex in Caenorhabditis elegans is determined by a regulatory cascade of seven interacting autosomal genes controlled by three X-linked genes in response to the X chromosome-to-autosome (X/A) ratio. XX animals (high X/A) develop as self-fertile hermaphrodites, and XO animals (low X/A) develop as males. The activity of the first gene in the sex-determining cascade, her-1, is required for male sexual development. XO her-1 loss-of-function mutants develop as self-fertile hermaphrodites, whereas XX her-1 gain-of-function mutants develop as masculinized intersexes. By genetic mosaic analysis using a fused free duplication linking her-1 to a cell-autonomous marker gene, we show here that her-1 expression in a sexually dimorphic cell is neither necessary nor sufficient for that cell to adopt a male fate. Our results suggest that her-1 is expressed in many, possibly all, cells and that its gene product can function non-autonomously through cell interactions to determine male sexual development.     

Amplification of chirality in two-dimensional enantiomorphous lattices

The concept of chirality dates back to 1848, when Pasteur manually separated left-handed from right-handed sodium ammonium tartrate crystals. Crystallization is still an important means for separating chiral molecules into their two different mirror-image isomers (enantiomers), yet remains poorly understood. For example, there are no firm rules to predict whether a particular pair of chiral partners will follow the behaviour of the vast majority of chiral molecules and crystallize together as racemic crystals, or as separate enantiomers. A somewhat simpler and more tractable version of this phenomenon is crystallization in two dimensions, such as the formation of surface structures by adsorbed molecules. The relatively simple spatial molecular arrangement of these systems makes it easier to study the effects of specific chiral interactions; moreover, chiral assembly and recognition processes can be observed directly and with molecular resolution using scanning tunnelling microscopy. The enantioseparation of chiral molecules in two dimensions is expected to occur more readily because planar confinement excludes some bulk crystal symmetry elements and enhances chiral interactions; however, many surface structures have been found to be racemic. Here we show that the chiral hydrocarbon heptahelicene on a Cu111 surface does not undergo two-dimensional spontaneous resolution into enantiomers, but still shows enantiomorphism on a mesoscopic length scale that is readily amplified. That is, we observe formation of racemic heptahelicene domains with non-superimposable mirror-like lattice structures, with a small excess of one of the heptahelicene enantiomers suppressing the formation of one domain type. Similar to the induction of homochirality in achiral enantiomorphous monolayers by a chiral modifier, a small enantiomeric excess suffices to ensure that the entire molecular monolayer consists of domains having only one of two possible, non-superimposable, mirror-like lattice structures.     

Molecular verification of the integration of Tripsacum dactyloides DNA into wheat genome through wide hybridization

RAPD and RFLP analyses of double haploid lines which derived from hybridization between hexaploid wheat (Triticum aestivum L.2n=42) and eastern gamagrass (Tripsacum dactyloides L.2n=4x=72) are reported.Two of the 340 Operon primers have been screened,which stably amplified Tripsacum dactyloides (male parent) specific bands in the double haploid lines.These results confirm the fact that Tripsacum dactyloides DNA has been integrated into wheat genome by sexual hybridization at molecular level.This idea has been further testified by RFLP analysis.Application and potentials of transferring Tripsacum dactyloides DNA into wheat genome by sexual hybridization in wheat breeding are discussed.     

具有两性的捕食者-食饵模型的渐近性态

研究具有Holling Ⅱ功能反应的捕食者食饵模型. 得到了食饵两性具有不同的出生率和死亡率时, 边界平衡点全局稳定的条件及食饵和捕食者一致持续生存的条件. 数值模拟表明, 捕食者的存在最终不会改变食饵的性别比例.     

Unusually dynamic sex roles in a fish

Sex roles are typically thought of as being fixed for a given species. In most animals males compete for females, whereas the females are more reluctant to mate. Therefore sexual selection usually acts most strongly on males. This is explained by males having a higher potential reproductive rate than females, leading to more males being sexually active (a male-biased operational sex ratio). However, what determines sex roles and the strength of sexual selection is a controversial and much debated question. In this large-scale field study, we show a striking temporal plasticity in the mating competition of a fish (two-spotted goby, Gobiusculus flavescens). Over the short breeding season fierce male-male competition and intensive courtship behaviour in males were replaced by female-female competition and actively courting females. Hence, sex role reversal occurred rapidly. This is the first time that a shift in sex roles has been shown in a vertebrate. The shift might be explained by a large decline in male abundance, strongly skewing the sex ratio towards females. Notably, the sex role reversal did not occur at an equal operational sex ratio, contrary to established sex role theory.     

噁唑硼烷催化还原二苯基已二酮的反应机理研究

本文用量子化学AM1方法研究了二苯基已二酮在唑硼烷催化还原下的对映体选择性反应机理 ,结果表明 ,在此硼催化剂的作用下 ,二苯基已二酮的还原对映体产物主要是R构型 ,其主要原因是两种对映体的催化过渡态的活化能相差较大所致 .用过渡态活化理论计算所得光学产率 %e .e .=99.7,研究结果与实验测定一致     

Condition-dependent signalling of genetic variation in stalk-eyed flies

Handicap models of sexual selection predict that male sexual ornaments have strong condition-dependent expression and this allows females to evaluate male genetic quality. A number of previous experiments have demonstrated heightened condition-dependence of sexual ornaments in response to environmental stress. Here we show that genetic variation underlies the response to environmental stress (variable food quality) of a sexual ornament (male eye span) in the stalk-eyed fly Cyrtodiopsis dalmanni. Some male genotypes develop large eye span under all conditions, whereas other genotypes progressively reduce eye span as conditions deteriorate. Several non-sexual traits (female eye span, male and female wing length) also show genetic variation in condition-dependent expression, but their genetic response is entirely explained by scaling with body size. In contrast, the male sexual ornament still reveals genetic variation in the response to environmental stress after accounting for differences in body size. These results strongly support the hypothesis that female mate choice yields genetic benefits for offspring.     

Rapid evolution of male reproductive genes in the descent of man

A diverse body of morphological and genetic evidence has suggested that traits pertaining to male reproduction may have evolved much more rapidly than other types of character. Recently, DNA sequence comparisons have also shown a very high level of divergence in male reproductive proteins between closely related Drosophila species, among marine invertebrates and between mouse and rat. Here we show that rapid evolution of male reproductive genes is observable in primates and is quite notable in the lineages to human and chimpanzee. Nevertheless, rapid evolution by itself is not necessarily an indication of positive darwinian selection; relaxation of negative selection is often equally compatible with the DNA sequence data. By taking three statistical approaches, we show that positive darwinian selection is often the driving force behind this rapid evolution. These results open up opportunities to test the hypothesis that sexual selection plays some role in the molecular evolution of higher primates.     

亚洲象野外及圈养条件下食物成分分析

分析了采自云南思茅野生亚洲象在野外主要取食的37种野生植物材料,取自北京动物园象馆圈养亚洲象的5种植物饲料样品及1种颗粒饲料样品.用凯氏定氮法测定蛋白质质量分数,用乙醚浸提法测定粗脂肪质量分数,用酸碱水解法测定粗纤维质量分数,高温烘干至恒重法测定干物质的质量分数,煅烧法测灰分质量分数,以分析亚洲象主要食物成分,并对比圈养条件下亚洲象食物与野外食物营养成分的差别.研究发现:亚洲象的野生食物与动物园饲喂食物的主要营养成分没有显著性差异,但野生食物中的钙元素的质量分数普遍高于饲料食物.饲料食物中钙的含量不足可能是导致圈养亚洲象低血钙症的主要原因.     

共振瑞利散射光谱法同时测定手性对映体的研究进展

自然界广泛存在具有手性的有机对映异构体,还有很多人工合成的手性化合物.这些手性化合物的物理化学性能相似相近,但其旋光性、生物活性和环境行为迥然各异.对这些有机对映体的手性识别和分离分析则是分析化学中很有吸引力的课题.人类对手性化合物的认识和手性识别经历了感性和理性的飞跃,尤其是对其手性识别从操作到理论分析,产生了许多手段和方法.但是适应不同要求的分离分析仍然在快速发展,尤其是不经分离而同时测定手性对映体的方法还在不断探索中.笔者拟用高灵敏度的共振瑞利散射光谱法为主的分子光谱分析方法进行深入研究,拟建立一种快速简捷高效的同时测定手性对映体的现代分析方法.     

房室不节对雄性小鼠生殖机能影响的初步研究

目的　通过比较不同造模方法对雄性小鼠生殖机能的影响 ,研究房室不节是否能影响雄性小鼠的生殖机能。方法　利用房室不节建立肾阳虚证雄性小鼠模型 ,同时以脾虚证、恐伤肾致肾虚证、氢化可的松致肾虚证为对照因素 ,比较造模小鼠的睾丸乳酸脱氢酶—同工酶 (LDH X)、母鼠怀孕活胎数、精子密度、精子活力、精子畸形数。结果　房室不节对雄性小鼠生殖机能的影响与对照组、脾虚组比较 ,有一定的统计学意义。结论　房室不节能影响肾阳虚雄性小鼠的生殖机能。     

Rapid evolution of reproductive barriers driven by sexual conflict

A growing amount of experimental data indicates extremely rapid evolution of traits and proteins related to fertilization in many diverging taxa. These data come from studies of sperm or pollen competition between closely related species, and from molecular studies of fertilization proteins. The positive selection for evolutionary novelty that appears to be acting on fertilization systems seems paradoxical because successful reproduction requires the close matching of female and male traits. It has been suggested that perpetual coevolution between the sexes can result from sexual conflict in mating. Sexual conflict occurs when characteristics that enhance the reproductive success of one sex reduce the fitness of the other sex. Numerous examples of sexual conflict resulting from sensory exploitation, polyspermy and the cost of mating have been discussed in detail. The potential for coevolution due to such conflict has been evaluated experimentally. Here I develop a simple mathematical model describing coevolutionary dynamics of male and female traits involved in reproduction. The model shows that continual change in such traits at a constant speed is expected whenever females (or eggs) experience fitness loss from having too many compatible males (or sperms). The plausibility of runaway coevolution increases with increasing population size. Rapid evolution of reproductive barriers driven by sexual conflict may explain increased speciation rates after colonization of new habitats ('adaptive radiation') and high species richness in resource-rich environments.