Habitat range of two alpine medicinal plants in a trans-Himalayan dry valley, Central Nepal

Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotechnologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare （Bruehl） Stapf and Neopicrorhiza scrophulariiflora （Pennel） Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. scrophulariiflora is exclusively found on cool and moist north facing slope between 4000 and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon （OC）, organic matter （OM）, total nitrogen （N） and carbon to nitrogen （C/N） ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil OC is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The C/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soil can be suitable for cultivation ofA. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaeiers may be a new threat in future to its habitat. The information about habitat conditions, together with the information from other areas, ean be useful to identify potential habitats and plan for cultivation or domestication of the two medieinal plants.     

人工育珠对三角帆蚌(Hyriopsis cumingii)遗传基因影响的初步研究

采用酚-氯仿和试剂盒两种提取法对三角帆蚌怀珠群与非怀珠群各6个个体进行基因组DNA的提取,然后在优化RAPD(随机扩增多态性DNA)检测条件基础上,从80个随机引物中筛选出12个扩增较好且多态性强的引物进行RAPD扩增,产物通过水平板琼脂糖凝胶电泳和垂直板聚丙烯酰胺凝胶电泳两种方法进行检验并对DNA的多态性进行分析。结果显示在怀珠群和非怀珠群检测到的位点数、多态位点比例、平均Shannon多态性信息指数、平均Nei's基因多样性指数、群体内个体间平均遗传相似率和平均遗传距离分别为100、33%、0.1927、0.1324、0.904、0.096,95、47.37%、0.2711、0.1879、0.861、0.139,群体间的平均遗传距离为0.821,非怀珠群的变异性大于怀珠群;本研究还获得了两群体各自的特异扩增谱带及两群体间表达差异较大谱带,这些位点很可能是由人工育珠所引起。根据MEGA4.0软件的UPGMA和NJ程序构建的分子系统树可直观地将两群体分开。     

Effects of vegetation and sewage load on mangrove crab condition using experimental mesocosms

Constructed wetlands, especially mangroves, have been studied for their usefulness in sewage treatment but the effects of mangrove vegetation and a sewage load on mangrove macrofauna have been given little attention. Ocypodid crabs are important components of mangrove forests and constitute good bioindicators of the functioning of the ecosystem as a whole. In constructed mangrove mesocosms, three vegetation treatments (bare substratum, and Avicennia marina and Rhizophora mucronata seedlings) were subjected to 0, 20, 60 and 100% sewage loads from a nearby hotel. The physiological condition of introduced Uca annulipes and Uca inversa was evaluated in terms of their RNA/DNA ratio after one, five and twelve months, and used as an indicator of ecological function in the system. Crab condition in 0% sewage load was similar to that of wild crabs throughout, suggesting no significant effects of the mesocosms on their RNA/DNA ratio. Overall, both species coped well with the administered sewage loads, suggesting good ecological function in the system. Both species manifested similar patterns in RNA/DNA ratio, being more affected by seasonal fluctuations than by sewage load and vegetation presence and type. Higher RNA/DNA ratios were recorded in the long compared to the short rainy season. Sewage enhanced crab condition in the bare substratum and R. mucronata treatments, especially after one year, probably as a result of enhanced food availability. Uca inversa may be more sensitive to sewage pollution than U. annulipes. In A. marina, no difference in crab condition was observed between sewage loads, and this mangrove yielded the best reduction in sewage impacts. Our results support the usefulness of constructed mangrove areas in sewage treatment, especially if planted with A. marina and inhabited by physiologically healthy ocypodid crabs to enhance the system's performance.     

Molecular ecological study of <Emphasis Type="Italic">Siganus spinus</Emphasis> and <Emphasis Type="Italic">S. guttatus</Emphasis> from Okinawan waters based on mitochondrial DNA control region sequences

The mitochondrial DNA (mtDNA) control region was sequenced to examine the genetic variability and gene flow of juvenile Siganus spinus and S. guttatus. In total, 461 nucleotide sequences were obtained from 69 specimens of juvenile S. spinus from Okinawa Island and Ishigaki Island, in which 17 variable sites and 22 haplotypes were identified. Haplotype diversity (h) was high (0.9244 in Okinawa and 0.8984 in Ishigaki), whereas nucleotide diversity (π) was low (0.0063 in Okinawa and 0.0059 in Ishigaki). The two populations were not genetically distinct. Siganus guttatus, which do not form large schools at recruitment, in contrast S. spinus, were also analyzed by studying 152 individuals collected off Okinawa Island, Miyako Island, and Ishigaki Island. Of 476 nucleotide sequences, 50 were variable, and 42 haplotypes were identified. Genetic variability values were high (h = 0.8766 and π = 0.0151 in Okinawa; h = 0.9640 and π = 0.0192 in Miyako; h = 0.9161 and π = 0.0199 in Ishigaki). The Okinawa population was genetically isolated from the Miyako and Ishigaki populations. As a result, genetic diversity was high for each of these siganid populations despite their being target species for fisheries; however, the degree of inter-population gene flow was higher for S. spinus than S. guttatus, suggesting that these species exhibit different dispersal strategies.     

用于养殖环境调控的微生物制剂评价方法的研究

为尝试建立对不同微生物制剂产品的客观评价方法体系,选择5种商品化复合微生物制剂,进行了菌数和主要组成种类等测定,并利用天然或人工模拟的养殖污水进行了不同微生物制剂对氨氮、亚硝酸态氮、COD等降解效果的比较,以及微生物制剂活化增效后的效果比较等.结果表明,不同的商业化复合微生物制剂在有益菌含量和水质污染降解效果方面存在较大差异.另外,微生物制剂在海水和淡水中以及是否经过活化,效果也存在较大差异.     

虾类遗传多样性的研究现状

同工酶技术已经被广泛应用于虾类群体遗传学及标记辅助选择育种等研究方面.同工酶电泳显示对虾有相应的亚群差异,暖水性虾类的遗传多样性水平高于冷温性种类;连续分布的且在不同生活史阶段所处的栖息地环境变化幅度大的种类往往表现出较低的遗传多态性,虾类群体的多态位点比例和杂合度都较低,养殖群体比野生群体更低.但同工酶电泳技术往往检测不出一些"隐性"或"中性"变异而低估了遗传多样性水平.随着分子生物学技术的发展,从20世纪90年代开始,虾类遗传多样性的研究逐渐向线粒体DNA和核DNA的多态性方向发展.限制性片断长度多态性(RFLP)在虾类线粒体多倍型、物种标记以及比较野生和养殖群体线粒体COI 基因的多态性比较等方面应用普遍.随机扩增多态性(RAPD)技术主要应用于虾类不同地理群体遗传多态性调查,养殖群体与野生群体之间、养殖群体世代之间的遗传多态性比较,该技术得到的虾类遗传多样性水平高于同工酶电泳技术.扩增片断长度多态性(AFLP)技术在虾类中主要应用于遗传连锁图谱的构建,有关虾类的AFLP遗传多样性分析的报道不多.利用AFLP技术对连续选育群体的遗传多样性研究显示,随着选育世代的增加,选育群体的遗传多样性呈现下降趋势,但随着选育时间的延长,群体之间的分化逐渐降低,群体的遗传结构开始趋于稳定,成为一个品系.单一重复序列(SSR)技术主要用于标记种群遗传特异性、不同地理群体间以及野生和养殖群体间的遗传多样性差异.DNA序列分析技术特别是线粒体序列分析技术近年来在虾类遗传多样性研究中的应用逐渐增多.mtDNACOI、mtDNA12S rRNA和mtDNA16S rRNA的基因序列差异被应用于形态相近物种的鉴别、亚属分类、确定个体间亲缘关系和野生与养殖群体间的遗传多样性差异等.为了实现对虾类种群遗传差异的更深入了解,人们把种群遗传结构的研究和系统地理学相结合,即用分子系统地理学的方法来研究遗传谱系空间分布的历史特征,通过种群遗传结构的分析来探讨种内系统地理格局的形成机制、系统发育关系以及现有分布特征,并结合种群的地理分布状况来发现和验证与其相关的地质事件,追溯和揭示种群的进化历程.从育种、养殖以及资源保护的角度出发,人们开始研究野生群体的种质基因库,希望根据群体遗传结构确定合理的增殖策略,制定科学的保护措施,确保虾类养殖业的持续发展.     

Degradation of rock fracture asperities in unloading,reloading, and reversal

Among the constitutive models for rock fractures developed over the years, Barton's empirical model has been widely used. Although Barton's failure criterion predicts peak shear strength of rock fractures with acceptable precision, it has some limitations in estimating the peak shear displacement, post‐peak shear strength, dilation, and surface degradation. The first author modified Barton's original model in order to address these limitations. Barton proposed his model for degradation of fracture asperities in unloading, reloading, and shear displacement reversal based on just one cyclic direct shear test. In this study, a database of results of 18 cyclic direct shear tests available in the literature was collected and analyzed. Modifications were made to Barton's original model (in terms of fracture cyclic shearing) to make it consistent with the modified model proposed by the first author. Copyright © 2010 John Wiley & Sons, Ltd.     

重视和加强中国东部地区土地退化整治研究

根据《２１世纪议程》土地荒漠化定义，从全球环境研究角度，论述了中国东部湿润、半湿润地区土地退化及其危害和开展中国东部地区土地退化研究的必要性和可行性，并提出了点面结合的初步研究设想。     

云南元谋干热河谷土地退化及其防治对策*

本文探讨了云南元谋干热河谷土地退化的特点、分布及其危害,提出了加强基础教育、控制人口增长、改革耕作制度、继续农业基础设施建设、因地制宜发展林业和农业等于热河谷土地退化防治对策。