首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 406 毫秒
1.
Boron is an essential nutrient for plants, but it is toxic in excess. Transgenic rice plants expressing an Arabidopsis thaliana borate efflux transporter gene, AtBOR4, at a low level exhibited increased tolerance to excess boron. Those lines with high levels of expression exhibited reduced growth. These findings suggest a potential of the borate transporter BOR4 for the generation of high-boron tolerant rice.  相似文献   

2.
Hall(1977)首次在新西兰的土壤中发现GlomusinjtequensHall。Ames和Schneider(979)在美国的加利福尼亚再次发现了这个种。他们认为该种与无梗囊霉(Acauloryora)有相似之处,抱子都是从泡囊发育而成,但无梗囊霉的抱于是在产抱囊的侧面形成,而该种的抱子则是在产抱囊柄的内部发育而成的。为此,Ames和Schneider(197)为这个种建立起一个新属——内养囊霉属(Entrophospora),把这个种改名为稀有内养囊霉Entrophoworam斤equens(HallAmesetSchnelder。SChellGk和Spain(1984)报道了这个属的另一个种哥伦比亚内养囊霉(Entro…  相似文献   

3.
庄巧生男1916年生现任中国农业科学院作物育种栽培研究所研究员,中国作物学会理事长。从事小麦科研事业50余年。在植物遗传育种领域,带领几代科技人员选育出“北京8号”、“北京10号”、“丰抗号”系列冬小麦新品种,种植面积分别达2000,900、1400万亩以上,累计增产45亿斤。在育种中他倡用复合杂交,重视新抗病源,强调不同基因源的聚合以丰富遗传背景。1981年主持全国小麦育种攻关以来,成效卓著,获国家、部级奖励7项。小麦和作物育种著作、论文40余篇。其中自花授粉作物遗传力估算和配合力分析推动了数量遗传学在国内的应用研究;《中国小麦品种及其系谱》一  相似文献   

4.
发生消长规律 关于小地老虎的发生数量消长,在前面发生特点中已略述及,即无论它是发生几代的地区,其猖獗为害的世代均为第一世代幼虫,其后各代幼虫群体数量骤减,对作物基本不会造成生产上的损失。为什么出现这种数量骤减现象  相似文献   

5.
中国的(亻莫)鼠(Mimomys)化石   总被引:8,自引:6,他引:2  
本文详细综述了中国的 Mimomys 属材料.分布青海共和、甘肃合水、河北阳原及辽宁林西的 M. (Villanyia) chinensis Kormos、在甘肃合水与 M. gansunicus Zheng 共生,其时代为泥河湾期(或晚维拉方期,相当于 MN 18); 分布陕西渭南、山西平陆、榆社及河北阳原的 M. orientalis Young 和欧洲种 M. stehlini Kormos、分布渭南的 M. youhenicus 和欧洲种 M. kretzoii Fejfar 分别处于大致相同的进化阶段并和一个与 M. banchiaonicus 相似的种类共生, 其时代均为游河期(或早维拉方期,相当于 MN 16); 山西襄汾的 M. peii sp. nov. 的时代为大柴期(或中维拉方期,相当于 MN 17); 山西离石的 M. cf. intermedius (Newton) 的时代为泥河湾期;山西屯留的 Mimomys sp. 的时代可能偏早,为西村期(可能相当于路西南期或 MN 15).  相似文献   

6.
首次报道了乐昌含笑(Michelia chapensis)的染色体数目和核型。核型公式为2n=38=28m+6sm+4st(2SAT)。与前人认为整个含笑属都为单一的2A型不同,乐昌含笑的核型属于Stebbins的2B型,具有2对近端着丝粒染色体。而且发现在第9对染色体上有小随体的存在。这些表明在含笑属内含有不同的核型。乐昌含笑在细胞学意义上可能是属内比较进化的类群。对染色体结构的细微改变在木兰科植物的种属进化上的作用进行了简要讨论。  相似文献   

7.
阎隆飞男 69岁北京农业大学生物学院植物生理及生物化学教授阎隆飞于1947年在菠菜叶绿体中首次发现碳酸酐酶,得到国外证实和公认。1963年他首次发现高等植物中存在收缩蛋白(肌动球蛋白),得到国外科学家证实,被广泛引用。1982年以后阎隆飞等证明:花粉、卷须、鳞茎中普遍存在肌动蛋白和肌球蛋白,肌动蛋白与肌球蛋白相互作用是细胞运动的动力,并在叶细胞的质膜上证明红膜肽(spectrin)等膜骨颦成分的存在,阎隆飞等从高粱叶绿体分离出系统Ⅰ、光系统Ⅱ基因,并将光系统Ⅱ psbD基因在大肠杆菌中表达。阎隆飞于1982年获得国家自然科学二等奖,1987年获国家教委科技进步二等奖。  相似文献   

8.
谢联辉植物病理学家。1935年3月生,福建龙岩人.现任福建农学院教授、博士导师。他长期从事植物病理学的教学科研工作,自1973年以来,在他主持下建立起一个颇具特色的植物病毒研究体系,系统研究了中国水稻、甘薯甘蔗、水仙以及福建烟草、蕃茄等植物病毒的种类、分布、测报和治理。先后发现、分离和鉴定的植物病毒有1个世界新记录。11个中国新记录和5个大陆新记录、并弄清其病原性质与传播途径,提出相应的防治措施,对发展我国植物病毒病学做出了突出贡献。他发现命名了一种新的病  相似文献   

9.
第五节大脑皮层的机能——高级神經活动本节是本章也是本書的高峯,是把过去学习过有关反射作用的知識进行总結和提高,使学生能从理論上理解神经对人的意义——保持內部各器官的协調,同外界环境的统一。  相似文献   

10.
第三节祖国在防治疾病上的伟大成就这节课是在学生已掌握了传染病的基本知識的基础上来进行講授的,首先在教材里提出以血吸虫病、天花、瘧疾、黑热病、痳疯等传染病說明了新旧社会的对比;同时也说明了社会主义社会制度的优越性。我們的党和政府对于人民健康的关怀是无微不至的,并且对于各种疾病的积极防治工作加强了党的领导,及时提出了一系列的方針、政策和措施;建立了专业防治机构,培养了专业干部;結合生产发动了广大羣众来参加防治。因此在防治各种传染病的工作中取得了很大的成績。  相似文献   

11.
大黄鱼精子的超微结构   总被引:44,自引:1,他引:43  
尤永隆  林丹军 《动物学报》1997,43(2):119-126
大黄鱼的精子由头产和尾部两部分组成。头部结构较为独特,其腹侧有一较大的细胞核,背部有中心粒复合体。头部的后端是袖套。细胞核的腹面稍向外突出背面则稍向内凹。细胞核中的染以质浓缩成致密的团块状。团块状的染色质之间分布着松散的纤维状染色质。植入窝位于细胞核的背部表面,由细胞核背面向内凹陷而成,呈一沟状,其走向与精子的长轴平行。  相似文献   

12.
本文详细描述了菱臼齿兽耳区各个部分的基本结构;并指出了耳区结构与某些啮齿类的相似性,以及中耳鼓泡组成成份与戈壁(犭亚)兽(Anagale gobiensis)的区别。  相似文献   

13.
1. After defining social wasps, an outline is given of their classification and possible evolution. The Vespidae probably arose in the Malayan region at about the beginning of the Tertiary period and spread from there all over the world. They are now highly developed in South America and it is suggested that they may have reached that country over the Behring Straits, probably in two waves, the first of an ancestral Polybiine, the second perhaps of Polistes only. 2. A biief account is given of the architecture of wasps' nests which is often specific to the genus. Nevertheless, there are examples of very similar wasps making very different nests and there does not seem any case for putting an overriding value on nest-architecture in classification. While we know sufficiently well what we have to explain, only a very small beginning has been made in describing and analysing the behaviour which produces the elaborate constructions we find. 3. In the familiar Vespinae the concepts of queen and worker are well defined and the two castes are discontinuous. In genera such as Polistes the position is much more fluid, particularly in the tropical species in which it is not necessary to have a queen specialized for hibernation. Some time after nest-production, however, a queen becomes recognizable, though often more by her behaviour than by her structure. In the Polybiini, queens and workers are sometimes well differentiated and sometimes not; but in most genera and species there is more than one queen in a nest. Other types of females not so well defined and of uncertain significance also occur. In temperate climates new colonies are founded by one or a few queens; in the tropics most colonies are founded by swarms of queens and workers. 4. The main differences between queens and workers seem to be determined in the larval stage, perhaps by some secretion administered by the adults, but clearly influenced by other factors as well. The full behavioural differences between the castes are often finally established by social interactions between the adults. 5. Males tend to be produced towards the end of the life of short-lived colonies or towards the end of the reproductive cycles of longer-lived colonies. There is need for more information about in- or out-breeding patterns, particularly in relation to specific differences in the degree of sexual dimorphism. 6. Very few pheromones are recognized with certainty and only one, the queen-substance of Vespa orientalis, has been identified chemically. However, some species produce a substance from the female sixth gastral sternite (Van der Vecht's organ) which at least in one genus is an ant-repellent. Some genera of Polybiines have a somewhat similar gland on the fifth sternite which may be connected with caste-differentiation. Some wasps (Vespula) produce a footstep pheromone concerned with the recognition of the nest entrance and there is less good evidence for the existence of significant substances in the saliva of workers and in their poison glands (alarm substance). 7. Trophallaxis, or the supply of salivary secretion by the larvae to adults more or less in exchange for the food provided from outside by the foragers, seems to be essential to the colonies of Vespa since the adults have no proteases. Trophallaxis also occurs in some Polistinae but its significance there is not known. 8. Social hierarchies of ‘peck orders’ are always established amongst the adults of Polistes and play a part in determining which of several potential queens becomes the acting one. They are also important in establishing the relations of the queen to the workers and of the latter amongst themselves. A similar hierarchy occurs in Belono-gaster. Some sort of hierarchy also exists amongst adult Vespula and is probably important in relation to trophallaxis, but the hierarchies must become less definite in large colonies with hundreds of individuals, especially if there is more than one queen. 9. The principal hurdle in the evolution of social behaviour is the establishment of genes which determine that some females lay most or effectively all of the eggs while others nurse, build and forage. This evolution may only be possible amongst females which are so closely related that their genomes are almost identical. In this connexion we need much more direct field evidence on the dispersal of queens, on mating systems and the incidence of multiple insemination. It appears that, once true social life is established, considerable diversification in nest architecture and social organization may happen relatively rapidly, probably much influenced by various ecological pressures, especially predation. 10. A number of species of Vespula, Vespa and Polistes have become social parasites, in the first and the last cases without a worker caste. This seems like a wrong turning taken in the course of the normal evolution of the queen-worker relationship. 11. A brief account is given of the attempts to provide a theoretical framework for the population dynamics of wasp-colonies. 12. An account is given of the relations of wasps, chiefly as foragers, with plants and with other animals.  相似文献   

14.
15.
16.
Abstract— Males of Idea tambusisiana , previously unstudied, lack the only known unequivocal synapomorphy associating the constituent members of Idea . Further cladistic analyses were performed on an expanded data matrix containing two characters alternatively coded in binary and multistate form. Two topologies were obtained of which one, in which I. tambusisiana remains internal to the genus, is accepted following consideration of information content and assessment of the supporting character states. A character analysis is also performed in which the problem of ambiguous charater state assignments to the internal nodes of the cladogram is examined. Biogeographic implications of the results are discussed with respect to areas of endemism in southeast Asia, the origin of Sulawesi (Celebes), and vicariance/dispersal models intended to explain the distribution of Idea species in relation to the Makassar Strait.  相似文献   

17.
18.
三峡水库秀丽白虾生长与繁殖生物学特征研究   总被引:1,自引:0,他引:1  
&#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &#  &# 《水生生物学报》2015,39(5):989-996
2012 年11 月至2013 年10 月逐月对三峡水库木洞江段秀丽白虾的生长和繁殖生物学特征进行了研究。结果显示秀丽白虾是一年生的虾类, 寿命为1214 个月。雌性个体的平均体长(37.727.92) mm 显著大于雄性(37.086.59) mm, 具有明显的雌雄异形现象。秀丽白虾的渐近体长(L)为59.33 mm, 生长系数(K)是1.6/年, 生长方程为:Lt=59.33-e-1.6(t+0.081)。雌虾繁殖季节从4 月上旬持续至9 月下旬, 繁殖高峰期为4 月中旬至6 月中旬, 由越冬虾和当年虾两个世代的繁殖群体组成。抱卵雌虾的体长为27.0753.71 mm, 平均体长(L50)为37.06 mm。雌雄性比月变化为1.112.36, 平均为1.46, 群体中雌性个体数量显著多于雄性(P 0.001)。绝对繁殖力(FA)为31294 粒, 相对繁殖力(FR)为(11522)粒/g。绝对繁殖力与体长呈幂函数关系(FA=0.0031L2.8632, r=0.72, n=106), 而与体重呈直线关系(FA=104.63W+9.9534, r=0.79, n=106)。卵径(D)平均值为(1215102) m。为合理保护和利用三峡水库秀丽白虾种群资源, 建议加强虾类捕捞管理, 繁殖期间(49 月)禁止捕捞虾类或限制捕捞强度。    相似文献   

19.
20.
丹江口水库马口鱼肠道寄生蠕虫群落结构   总被引:4,自引:1,他引:3  
从2004年8月到2005年11月在丹江口水库调查的847尾马口鱼(Opsariichthys bidens)肠道内共获得寄生蠕虫14种,其中线虫7种,复殖吸虫4种,棘头虫2种,绦虫1种。该寄生蠕虫群落以广谱性寄生虫为主。杜父鱼驼形线虫(Camallanus cotti)、鱊头槽绦虫(Bothriocephalus acheilognathi)、卡斯杆咽线虫(Rhabdochona cascadilla)和木村小棘吻虫(Micracanthorhynchina motomurai)为群落的核心种。研究结果表明,寄生蠕虫群落随着马口鱼的体长和食性的改变而发生显著的变化。群落核心种的感染强度与马口鱼体长呈显著相关关系。种间相关性分析表明群落结构呈非随机组合,种间感染强度存在显著的相关性。同时群落种间关系受到马口鱼的体长和食性以及季节变化的显著影响。马口鱼肠道寄生蠕虫群落在宿主较大个体或夏秋季节中更容易形成显著的种间相关性。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号