Sex differences in learning in chimpanzees

The wild chimpanzees in Gombe National Park, Tanzania, fish for termites with flexible tools that they make out of vegetation, inserting them into the termite mound and then extracting and eating the termites that cling to the tool. Tools may be used in different ways by different chimpanzee communities according to the local chimpanzee culture. Here we describe the results of a four-year longitudinal field study in which we investigated how this cultural behaviour is learned by the community's offspring. We find that there are distinct sex-based differences, akin to those found in human children, in the way in which young chimpanzees develop their termite-fishing skills.     

Sex differences in emigration and mortality affect optimal management of deer populations

Populations of red deer that are limited by food, like those of many other ungulates, commonly include more females than males. We assessed the contribution of variation in sex- and age-specific rates of mortality and emigration to density-dependent changes in the adult sex ratio, using long-term observations and demographic experiments involving the red deer population on Rum, Scotland. We incorporated these effects in a stochastic model of local populations under different management regimes to show here that, when female numbers are allowed to increase to more than 60% of the ecological carrying capacity, the sustainable annual harvest of males from local deer populations will fall. Because males are typically culled by fee-paying hunters and generate more income than females, income will decrease as the male harvest falls. Because numbers of female deer throughout much of the Highlands probably exceed the threshold at which male density starts to be affected, many managers might be able to raise income from local deer populations by reducing female numbers, with potential benefits to the vegetation of Scottish Highland environments.     

Maternal control of resting-egg production in Daphnia.

Many planktonic organisms produce 'resting' stages when the environmental conditions deteriorate. Like seeds, resting stages can survive unfavourable conditions. The crustacean Daphnia normally reproduces by means of parthenogenetically produced normal, not resting, eggs-but occasionally switches to bisexual reproduction, which results in two resting eggs encased in a robust structure carried on the back of the female. This 'ephippium' is shed with the next moult, and can survive dormant for many years. The induction of resting-egg production requires multiple environmental stimuli, one of them being photoperiod. The switch from production of parthenogenetic eggs to resting eggs in Daphnia has recently been shown to be influenced by a maternal food effect. Here we present evidence that female Daphnia transmit information not only about food but also on photoperiod to their offspring, and influence the production of resting eggs in the next generation. The combined maternal effects can be relevant for the correct timing of resting-egg production-for example, in discriminating between spring and autumn conditions.     

劳伦斯的性伦理在《查泰莱夫人的情人》中的体现

劳伦斯的性伦理——男人与女人之间的“灵”与“肉”的完美统一,在小说《查泰莱夫人的情人》中淋漓尽致地体现出来。在小说《查泰莱夫人的情人》中作者不惜花费大量的篇幅描写“性”,旨在揭露工业革命对男女两性关系的异化。劳伦斯渴求通过建立新的、和谐的、完美的男女关系以改造社会,从而实现人性的复归。     

饲粮锌对蛋鸡生产性能及生殖激素的影响

试验选用66只18周龄商品代伊莎褐育成母鸡。随机分为3组,每组22只,对照组饲喂基础饲粮,试验1、2组在基础饲粮中分别添加601、80 mg/kg的锌,研究不同锌添加水平对蛋鸡生产性能和血清中生殖激素的影响。结果表明,在蛋鸡饲粮中添加锌对产蛋量、耗料量和料蛋比无显著影响（P〉0.05）,但破蛋率略下降,蛋重显著降低（P〈0.05）;试验1组血清中E2含量显著高于对照组（P〈0.05）,与试验2组无显著差异（P〉0.05）;试验2组与对照组亦无明显差异（P〉0.05）;而血清中P4含量3组间无显著差异（P〉0.05）。     

劳伦斯的性伦理在《查泰菜夫人的情人》中的体现

劳伦斯的性伦理——男人与女人之间的“灵”与“肉”的完美统一，在小说《查泰莱夫人的情人》中淋漓尽致地体现出来。在小说《查泰莱夫人的情人》中作者不惜花费大量的篇幅描写“性”，旨在揭露工业革命对男女两性关系的异化。劳伦斯渴求通过建立新的、和谐的、完美的男女关系以改造社会，从而实现人性的复归。     

Evolution of ecological differences in the Old World leaf warblers.

Sympatric species that belong to the same ecological guild usually differ in their behaviour and morphology, and these differences are often interpreted as adaptations to having to make use of different resources. Evidence supporting this interpretation comes from association between ecology and morphology among species, in which an a priori functional relationship is reasonable. But one problem with such comparisons is that members of a guild may be closely related, so the more closely related species can share a greater similarity in their morphology and ecology simply as a result of the lingering legacy of a common ancestor. In principle, the importance of historical legacy can be evaluated from phylogenetic relationships and times since divergence for all species, but this is rarely possible because these data are not available. Here we use a phylogeny for eight sympatric species of warbler in the genus Phylloscopus, based on their mitochondrial DNA sequences, to remove the effects of historical legacy. Without these effects, we find strong support for adaptive interpretations of among-species variation in habitat selection, prey-size choice and feeding method. Ecological variation along any of these three niche axes is associated with predictable morphological variation. We also find evidence for historical legacy in that more closely related species are often more similar behaviourally and morphologically. This paradoxical result can be reconciled because the most closely related species tend to differ along only one niche axis, habitat choice. In contrast, the evolution of prey-size choice and feeding method occurred rapidly and early in the diversification of this group. Once a new ecological zone was occupied, subsequent morphological change along these niche axes was limited, accounting for the similarity of closely related species.     

罗汉果性别相关的RAPD标记

应用随机扩增多态性DNA(RAPD)技术寻找与罗汉果性别相关的分子标记,筛选了130个10 bp的随机引物,发现有4个引物(S60、S90、S100、S343)能在雌、雄株DNA间扩增出5条差异性片段,大小在300~1 300 bp之间,表明这些特异带可被用来作为性别鉴别的特异性分子遗传标记。     

垂柳(Salix babylonica L.)雌雄植株的早期鉴别

用聚丙烯酰胺凝胶电泳法对已经开花的垂柳植株和经扦插由营养枝转变为幼苗状态的不同性别植株进行了过氧化物酶同工酶的测定,发现在每月份内成年雄株的过氧化物酶同工酶带均多于雌株,而幼苗状态的植株在该种的开花季节同工酶谱带的状况与成年株相似,雄株明显多于雌株,在其余月份里差别不显著,只在A区内,雄株有一条活性很弱的酶带,而雌株中缺失。实验表明过氧化物酶同工酶可以作为鉴别垂柳苗木雌雄性别的生化指标,但在该种的开花季节内较明显。     

不同种源苦楝种子生物学特性差异

对不同物候区10个产地的苦楝(Melia azedarach L.)种子采样分析,分别测定种子的纵径、横径、纵横径比、千粒质量、含水量、发芽率、发芽指数、活力指数、呼吸速率等种子生物学参数。结果表明:不同种源苦楝种子的形态存在显著差异,但与各地的地理、环境因子无显著相关;种子的大小具有一定的纬度变异,种子形状随纬度变化有分异,分布纬度越高,种子越接近圆球形。根据种子形态特征,将10个种源种子性状自然分布划分为5个类群。不同种源苦楝种子发芽率、发芽指数、活力指数和呼吸速率也存在显著差异;发芽率、发芽指数、活力指数与呼吸速率显著相关,而与种子形态无相关性,表明苦楝种子活力更多受种子生理生化状况的影响。     

Direct expression in Escherichia coli of a DNA sequence coding for human growth hormone.

DNA coding for human growth hormone was constructed by using chemically synthesised DNA in conjunction with enzymatically prepared cDNA. This 'hybrid' gene was expressed in Escherichia coli under the control of the lac promoter. A polypeptide was produced having the size and immunological properties characteristic of mature human growth hormone.     

Activation of latent Ca2+ channels in renal epithelial cells by parathyroid hormone.

Calcium has an important role in regulating epithelial cell ion transport and is itself transported by tissues involved in the maintenance of extracellular Ca2+ homeostasis. Although the mechanism of Ca2+ entry in electrically excitable cells is well-documented little is known about it in epithelial cells. Calcium absorption in polarized epithelial cells is a two-step process in which Ca2+ enters cells across apical plasma membranes and is extruded across basolateral membranes. Efflux may be mediated by an energy-dependent Ca2(+)-ATPase or by Na+/Ca2+ exchange. We examined Ca2+ influx in single cultured cells from distal renal tubules sensitive to parathyroid hormone by measuring intracellular Ca2+. Our results demonstrate that parathyroid hormone activates dihydropyridine-sensitive channels responsible for Ca2+ entry. We also show that microtubule-dependent exocytosis stimulated by parathyroid hormone may be necessary for the insertion or activation of Ca2+ channels in these cells. Once inserted or activated, dihydropyridine-sensitive channels mediate Ca2+ entry into these Ca2(+)-transporting epithelial cells. Our results support the view that agonist-induced exocytosis may represent a general paradigm for modulation of transport in epithelial cells by delivery and incorporation of transport proteins to plasma membranes or by delivery to plasma membranes of factors regulating these proteins.