Constraint to adaptive evolution in response to global warming

We characterized the genetic architecture of three populations of a native North American prairie plant in field conditions that simulate the warmer and more arid climates predicted by global climate models. Despite genetic variance for traits under selection, among-trait genetic correlations that are antagonistic to the direction of selection limit adaptive evolution within these populations. Predicted rates of evolutionary response are much slower than the predicted rate of climate change.     

嘎拉苹果高温处理与果实日灼的关系

 高温处理对诱导果实增强对日灼的抗性有一定的作用 ,可降低日灼率。苹果果实在 4 5℃下处理 2h ,在3d后将处理果和对照果同时暴露在阳光下 ,结果发现 :热处理能够在一定程度上增强果实对日灼的抗性。在 4 5℃下处理 2、4和 6h后立即取样或室温下放置 2 4h后取样 ,对热激蛋白的分析表明 ,大分子量热激蛋白量变化不大 ,而小分子量热激蛋白可能在诱导果实抗热性方面起重要作用。随着处理时间延长 ,在一定时间范围内 ,热激蛋白抗热性水平增加。经测定 ,树冠外围充分曝光果和树冠内膛遮荫果对比 ,二者热激蛋白含量有显著差异 ,这可能是遮荫果对日灼更为敏感的原因。     

水稻育秧阶段应注意的问题

俗话说:"壮秧八成粮".多年的生产实践证明:培育壮苗既是高产的基础,又是优质的前提.下面就水稻育秧阶段应注意的问题,谈一些粗浅的看法.     

基础化学教学中如何突出学生主体地位

从目前的教学模式来看 ,基础化学的教学仍然在采用传统的“传授知识———接受知识”的模式。这种模式 ,实际上就是“以教师为中心 ,以课堂为中心 ,以课本为中心”的“三中心”教学制度。它的保守性在于 ,以教师为中心 ,也就是以教师为主体 ,把学生当作被动的客体 ,维护教师的绝对权威 ,这与当代教育自由平等的原则是相悖的 ,限制了学生的思维 ;以课堂为中心 ,易形成满堂灌 ,使教学脱离实际 ,脱离社会 ,教师的课讲得很好 ,学生实际理解的东西也比教师认为他们能够理解的东西要少 ,使教学效果不尽如人意 ,必须进行较大力度的改造 ;以课本为中…     

农业院校水生生物学教学中学生学习主动性的培养

从激发学生学习兴趣、加强学生参与、注重实验教学和优化考试制度等4个方面入手,达到提高水生生物学教学效果的目的。     

Histopathology in Swines Exposed to

用质量分数为10%的狗舌草饲料喂猪144 d,病理组织学特征变化为,肝脏出现巨肝细胞;肾脏近曲小管上皮细胞肿大,胞浆内陷;大脑神经细胞出现卫星化和噬神经现象,小脑浦肯野氏细胞肿胀,尼氏小体不清;心肌纤维颗粒变性,有的核变圆,淡染。透射电镜检查可见肝细胞核常染色质数量增加,异染色质边集,胞质内充满嵴溶解的线粒体,内质网及高尔基体消失;Ⅰ型肺泡上皮细胞核膜破裂;Ⅱ型肺泡上皮细胞游离端微绒毛增多,嗜锇性板层小体减少。     

Coming in to the foodshed

Bioregionalists have championed the utility of the concept of the watershed as an organizing framework for thought and action directed to understanding and implementing appropriate and respectful human interaction with particular pieces of land. In a creative analogue to the watershed, permaculturist Arthur Getz has recently introduced the term “foodshed” to facilitate critical thought about where our food is coming from and how it is getting to us. We find the “foodshed” to be a particularly rich and evocative metaphor; but it is much more than metaphor. Like its analogue the watershed, the foodshed can serve us as a conceptual and methodological unit of analysis that provides a frame for action as well as thought. Food comes to most of us now through a global food system that is destructive of both natural and social communities. In this article we explore a variety of routes for the conceptual and practical elaboration of the foodshed. While corporations that are the principal beneficiaries of a global food system now dominate the production, processing, distribution, and consumption of food, alternatives are emerging that together could form the basis for foodshed development. Just as many farmers are recognizing the social and environmental advantages to sustainable agriculture, so are many consumers coming to appreciate the benefits of fresh and sustainably produced food. Such producers and consumers are being linked through such innovative arrangements as community supported agriculture and farmers markets. Alternative producers, alternative consumers, and alternative small entrepreneurs are rediscovering community and finding common ground in municipal and community food councils. Recognition of one's residence within a foodshed can confer a sense of connection and responsibility to a particular locality. The foodshed can provide a place for us to ground ourselves in the biological and social realities of living on the land and from the land in a place that we can call home, a place to which we are or can become native.     

展望未来几年--我们应该做些什么

现中国计算机学会常务理事,计算机专家,中国工程院院士汪成为,长期从事模拟计算机、数字计算机、系统仿真、人工智能的研究,主持或参与了导弹、计算机、大型软件、智能化决策、国防、武器战略等课题。曾任国家“863”智能计算机专家组组长、国家专家顾问组成员、信息化咨询委员等职。最近在《计算机世界》发表文章指出:“信息技术虽然发展迅速,但它却不很合理,离实际需求还有很大的差距,……展望未来几年,我们应该做些什么?”现摘录要点,供《计算机与农业》读者思考。     

哲学原理课教学如何指导学生读点原著

“马克思主义哲学原理”课在我国高等教育中占有特殊地位, 是对青年大学生进行科学的世界观、人生观、价值观教育的主渠道。近年来, 为了激发大学生对哲学原理课的兴趣, 塑造大学生“ 求真明善审美”的理想人格, 我们在教学内容和方法上做了大量有益的探索, 尤其在指导学生读点马列原著方面, 我们形成了一套行之有效的教学方法, 即“四步法”: 原著的精选、讲授、辅导、考核, 大大提高了哲学原理课教学的实效。     

Adipose tissue: ability to respond to nerve stimulation in vitro

Electrical stimulation of nerves to isolated rat and rabbit adipose tissue in vitro causes production of free fatty acids. Starvation increases the response. The response of white (epididymal) fat is prevented by sympathetic denervation. Direct evidence is provided showing that adipose tissue has the capacity to be an effector organ responsive to the nervous system.     

Bioassay to Forecast Cereal Cyst Nematode Damage to Wheat in Fields

Several simple agronomic practices such as crop rotation, timing of sowing, no-till management, and resistant cultivars can reduce damage by the cereal cyst nematode (CCN), (Heterodera avenae), but the damage levels are unpredictable. The objective of the present study was to develop a fast assay that would forecast the potential damage to wheat by CCN in the fields. Our forecast procedure was based on the SIRONEM bioassay with several modifications in the sampling and incubation of field soil samples and cultivation in them of wheat seedlings. For CCN disease assessment, a damage model that takes account of CCN infection and its damage to roots was developed. Field experiments were established to validate the resulting damage model, and showed a correlation between the forecast damage and field rating of CCN infection. This assay has advantages over other CCN estimation methods because it directly forecasts the potential crop damage in the field and it requires a relatively short period to obtain the data. According to the forecast damage and weather conditions, the most appropriate crop management regime, especially of sowing, can be chosen for each field assayed.     

小麦幼苗根系形态对镉胁迫的响应

为了研究镉(Cd)在小麦体内的吸收、转运过程,以及Cd对小麦根系形态的影响,本文通过水培试验分析了小麦在5种Cd水平下(0、0.5、5、50、200μmol·L~(-1))处理3、6、11、17 d和23 d后各项生长指标的变化,并用荧光显微镜观察了Cd处理17 d后小麦根系形态的变化情况。结果表明,小麦幼苗对Cd的吸收能力与Cd浓度成反比关系,且在Cd0.5处理下,小麦对Cd的吸收和转运的能力显著高于其他处理。随着Cd处理浓度的增加,小麦幼苗的生物量、株高、总根长、根体积、总根尖数目逐渐减小,根系平均直径逐渐增加。相关性分析结果表明,小麦幼苗对Cd的吸收能力与平均直径呈显著正相关,对Cd的转运能力仅与平均直径呈显著负相关。进一步通过荧光显微镜观察,结果显示Cd处理可诱导小麦幼苗根系皮层细胞增多、薄壁细胞增大以及内皮层细胞壁木质素的沉积。Cd诱导的根系直径增粗对小麦Cd的吸收及转运都起着非常重要的作用。     

抗病育种相关基因的研究进展

对肾小管发育不良、Chondrodysplastic矮小症、普鲁氏菌病和CARD15等一些与疾病相关基因的研究状况进行简单的回顾。     

改善动物福利 重视养羊驱虫

养羊是畜牧业发展的重要组成部分,又是国家提倡发展节粮型草食家畜的重点,为满足人民的肉食需求及繁荣"三农"经济作出了很大的贡献。然而由于羊寄生虫病的为害,造成了重大的环境污染与经济损失。针对羊寄生虫病的预防、治疗和病原灭绝3个环节,提出了相应的防制措施。     

进入《SCI》的海洋与水产学科期刊投稿指引

通过分析SCI的评价功能、选刊原则和期刊收录情况,为海洋与水产学科的科研人员提供向SCI源期刊投稿的指引。     

今后粮食生产的重点是增加饲料粮——以陕西省农牧业发展为例的探讨

预计到本世纪末,由于人口和粮食几乎是同步增长,按人平均占有的饲料粮恐难于有很大提高,今后粮食生产的发展除保证人口增长所需的口粮外,主要是努力增加饲料粮生产。尽快改变粮、饲不分的传统习惯,因地制宜改革种植业结构,发展能蛋比适宜的优质饲料作物生产,提高饲料转化效率,是发展动物性食物生产,改善人民食物构成的关键所在。对陕西来说,汉中水田区在越冬作物中发展饲料大麦;关中平原灌区推行玉米间作大豆;渭北旱原适当发展苜蓿,实行草粮轮作,均是强化农牧结合的有效途径。     

Female feathering in sebright cocks is due to conversion of testosterone to estradiol in skin

Sebright cocks develop a female feathering pattern but revert to normal male feathering after castration. Administration of testosterone to castrated cocks causes male comb development and reappearance of female feathering. Dihydrotes-tosterone treatment supports development of a male comb but does not induce female feathering. Since testosterone but not dihydrotestosterone is converted to estradiol in the skin of the Sebright, the female feathering appears to be the result of increased conversion of testosterone to estradiol.