998 resultados para 61.198
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Contents: UNCSD: Rio+20. Shrimp Aquaculture in Central America. Sovereign Rights of Indigenous Fishers. Access to Fisheries Information. Harmonizing Fishworkers’ Rights. The Delhi MPA Workshop.
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There is apparently great scope for improvement of the design and operational aspects of the gear particularly for the effective exploitation of seasonal fisheries like that of seer, tuna, barracuda etc. In order to evolve improved, yet cheap trolling gear regular investigations were undertaken by the Craft & Gear Wing of the Central Institute of Fisheries Technology, off Cochin for five fishing seasons and the results of these studies are incorporated in this paper.
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光敏核不育水稻农垦58S是石明松于1973年在晚粳农垦58的大田中发现的雄性不育突变体,它在长日照下雄性不育可被用于与恢复系杂交生产杂种,而在短日照下雄性可育能用于自交繁殖,它的恢复系来源广泛。基于这些特性,育种学家用光敏核不育水稻建立的二系杂交水稻制种技术有很大的应用潜力。近十几年来,育种学家用农垦58S作基因供体转育了许多新的不育系,研究结果表明育成的粳型不育系均为光敏不育系,但在育成的籼型不育系中,绝大多数丧失光敏核不育特性,变成温敏不育系。目前因不知光敏核不育的分子遗传机制,尚不能解释这些问题。 本文用双向电泳技术分析了农垦58S和农垦58苗期和育性转换光敏感期叶绿体蛋白质的差异,在农垦58S中发现三个蛋白质(Pl,P2和P3),其中Pl和P2在苗期和光敏感期叶片内均存在,P3仅在光敏感期的叶片中存在,它们不受长日照或短日照处理的影响。农垦58没有这三个蛋白质。 用制备型双向电泳纯化后,得到SDS - PAGE和IEF纯的Pl和P2。经SDS-PAGE和IEF测定,Pl的等电点是6.2,分子量是41 kDa;P2的等电点是5.8,分子量是61 kDa。现称Pl为P41,P2为P61。氨基酸序列分析和同源性检索发现P41与水稻叶绿体ATP合成酶p亚基和酵母转录因子CAD1有同源性,此外,P41的N-端序列中有一个与蛋白激酶催化核心中的多功能motif Y-G-X-G-X- (P/T)-G-V相似的序列;P61的14个氨基酸长的N-端序列与水稻叶绿体ATP合成酶β亚基的一致。P41和P61 N-端前12个氨基酸的序列也完全一致。 PCR扩增和Southern杂交分析没有发现农垦58S和农垦58之间ATP合成酶β亚基基因(atpB)的多态性。Nothern杂交分析表明农垦58S中仅有一种、与农垦58 atpB mRNA分子量相同的atpB转录产物,但它的atpB mRNA丰度明显低于农垦58的。没有检测到突变的atpB和其它形式的atpB转录产物。 分析P41和P61在其它水稻材料中的分布特点发现它们在粳型光敏不育系7001S、5088S、31301S、C407S和1647S,籼型光敏不育系W7415S和W9451S以及温(光)敏不育系培矮64S中存在,而在对照材料三系水稻马协A、珍汕97A、马协B、珍汕97B和明恢63以及常规粳稻C94153中不存在。根据这些不育系的系谱和它们与农垦58S之间基因的等位性研究结果,讨论了P41和P61与光敏核不育性的可能联系。
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Zhikong scallop (Chlamys farreri Jones et Preston 1904) is one of the most important aquaculture species in China. The development of a genetic linkage map would provide a powerful tool for the genetic improvement of this species. Amplified fragment length polymorphism (AFLP) is a PCR-based technique that has proven to be powerful in genome fingerprinting and mapping, and population analysis. Genetic maps of C. farreri were constructed using AFLP markers and a full-sib family with 60 progeny. A total of 503 segregating AFLP markers were obtained, with 472 following the Mendelian segregation ratio of 1:1 and 31 markers showing significant (P< 0.05) segregation distortion. The male map contained 166 informative AFLP markers in 23 linkage groups covering 2468 cM. The average distance between markers was 14.9 cM. The female genetic map consisted of 198 markers in 25 linkage groups spanning 3130 cM with an average inter-marker spacing of 15.8 cM. DNA polymorphisms that segregated in a 3:1 ratio as well as the AFLP markers that were heterozygous in both parents were included to construct combined linkage genetic map. Five shared linkage groups, ranging from 61.1 to 162.5 cM, were identified between the male and female maps, covering 431 cM. Amplified fragment length polymorphism markers appeared to be evenly distributed within the linkage groups. Although preliminary, these maps provide a starting point for the mapping of the functional genes and quantitative trait loci in C. farreri.
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于2000---2002年的鸟类繁殖期在中国科学院海北高寒草甸生态系统定位站,测定了27窝角百灵(Eremophtla alpestns)和43窝小云雀(Alauda gulgula)的巢址特征,观察了两者在繁殖期巢数的季节变化,并运用稳定性同位素技术测定了育雏食物,对两种百灵的巢址特征和食物重叠度进行了比较。结果表明两者的巢址特征存在着显著的不同:角百灵的巢开放度为92.16%,小云雀的为34.61%,前者的巢开放度显著大于后者(P<0.01);角百灵距巢100 em范围内遮蔽物的数量为0.070.26,小云雀的为2.571.19,前者显著少于后者(P<0.01);角百灵巢址植被的高度和盖度也显著小于小云雀的(P<0.01)。角百灵和小云雀均以小型昆虫育雏,育雏食物的资源重叠程度很高,为O.8957;而且两者的繁殖季节和繁殖强度也是相互重叠的。这两种百灵鸟类在巢址的选择上存在着一种代价和利益的权衡关系,巢址选择是捕食压和热条件共同作用的结果。二者共存的机制是巢址上的分化。
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Polyploidization plays an important role in generating the current high diversity of plants. Studies of distributional patterns of diploids and derivative autopolyploids have provided important insights into evolutionary processes and cryptic speciation of polyploidization within species defined on the basis of their morphology. However, few studies have been designed to examine distributions of infrageneric diploids and polyploids on the Asian Qinghai-Tibetan Plateau (QTP). Allium przewalskianum occurs widely on the QTP and in adjacent regions, at altitudes ranging from 2000m to 4500m. We collected a total of 844 individuals from 62 populations and determined their cytotypes over the entire distribution range of this species. Tetraploids tend to occur at high altitudes; however, the positive relationship between the ploidy and altitude was only marginally significant (P < 0.05). Contact zones between diploids and tetraploids were recorded on the eastern QTP from north to south. Four populations were found to harbor both cytotypes, but no triploid individuals. The wider distribution of tetraploids may be mainly due to their greater colonization ability in the new niches created by the Quaternary climatic oscillations in the QTP region. Our results offer a fundamental framework for studying evolutionary origins, adaptations and cryptic divergences of polyploids within this species complex based on molecular and/or ecological examinations in the future.
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11 fotografías a color.