白颊长臂猿染色体的研究

用各种染色体显带技术对云南南部的白颊长臂猿核型进行了详细研究, 并探讨了与其它长臂猿间的亲缘关系及核型进化的可能途径。它的2n=52, 核型公式为44(M或SM)+6(A), xy(M,A)。C带表明一些染色体着丝点C带弱化; 有的染色体出现插入的和端位的C带; X染色体两臂有端位C带, Y染色体是C带阳性和晚复制的。Ag-NORs的数目, 雌体有4个, 雄体有5个, Y染色体上具NOR。对白颊长臂猿与其它长臂猿间的亲缘关系和核型进化的可能途径进行了讨论。

倪氏复口吸虫的寄生对鲢及其耳石生长的影响

采用人工感染的方法研究倪氏复口吸虫的寄生对鲢幼鱼生长的影响,并观察和分析了鲢耳石的相关变化。结果表明,随着倪氏复口吸虫后囊蚴在鲢幼鱼眼球中发育成熟,鲢幼鱼的体重与体长,耳石质量与长径依然呈指数比例生长关系,但耳石质量与日龄之间则没有线性相关关系;另外倪氏复口吸虫后囊蚴的寄生不仅严重影响了鲢的生长,而且还致使鲢的大部分耳石上产生了标记轮。

利用抑制差减杂交技术分离三角褐指藻在缺氮条件下上调表达的基因

为了阐明硅藻利用氮源的分子机制,以三角褐指藻为材料,利用抑制差减杂交技术,分离鉴定了16个在缺氮诱导条件下上调表达的基因片段。其中,与已知功能基因具有较高相似性的有7种,都是跟氮源的吸收利用相关的。Northern blotting验证其中5个基因,包括硝酸盐转运蛋白基因、铁氧化还原蛋白亚硝酸还原酶基因、铵盐转运蛋白基因、结合ATP盒的转运蛋白基因和嘌呤透过酶基因,在缺氮诱导条件下转录水平有明显上调。

扁担塘螺类生产力的研究Ⅰ.铜锈环棱螺的周年生产量

１９９６—１９９７年对扁担塘螺类优势种之一铜锈环棱螺进行了周年研究，结果表明其种群含四个年龄组，其中１９９６年组生长最快，其带壳湿重瞬时生长率为４．１５，去壳干重瞬时生长率为３．４０。采用瞬时生长率法测算其周年生产量为：带壳湿重，１５．７７ｇ·ｍ－２·ａ－１；去壳干重，０．８６２４ｇ·ｍ－２·ａ－１。Ｐ／Ｂ系数基本一致，分别为０．５０，０．５１。铜锈环棱螺的生产量的去壳干重（Ｗｄ，ｇ·ｍ－２·ａ－１）和带壳湿重（Ｗｗ，ｇ·ｍ－２·ａ－１）满足下列关系：Ｗｗ＝１７．２０Ｗｄ。

Numerical analysis of shallow foundations under combined horizontal and torsional loading

Foundations of subsea infrastructure in deep water subjected to asymmetric environmental loads have underscored the importance of combined torsional and horizontal loading effects on the bearing capacity of rectangular shallow foundations. The purpose of this study is to investigate the undrained sliding and torsional bearing capacity of rectangular and square shallow foundations together with the interaction response under combined loading using three-dimensional finite element (3D-FE) analysis. Upper bound plastic limit analysis is employed to establish a reference value for horizontal and torsional bearing capacity, and an interaction relationship for the combined loading condition. Satisfactory agreement of plastic limit analysis (PLA) and 3D-FE results for ultimate capacity and interaction curves ensures that simple PLA solution could be used to evaluate the bearing capacity problem of foundation under combined sliding and torsion.

Distinct Evolutionary Patterns Between Two Duplicated Color Vision Genes Within Cyprinid Fishes

We investigated the molecular evolution of duplicated color vision genes (LWS-1 and SWS2) within cyprinid fish, focusing on the most cavefish-rich genus-Sinocyclocheilus. Maximum likelihood-based codon substitution approaches were used to analyze the evolution of vision genes. We found that the duplicated color vision genes had unequal evolutionary rates, which may lead to a related function divergence. Divergence of LWS-1 was strongly influenced by positive selection causing an accelerated rate of substitution in the proportion of pocket-forming residues. The SWS2 pigment experienced divergent selection between lineages, and no positively selected site was found. A duplicate copy of LWS-1 of some cyprinine species had become a pseudogene, but all SWS2 sequences remained intact in the regions examined in the cyprinid fishes examined in this study. The pseudogenization events did not occur randomly in the two copies of LWS-1 within Sinocyclocheilus species. Some cave species of Sinocyclocheilus with numerous morphological specializations that seem to be highly adapted for caves, retain both intact copies of color vision genes in their genome. We found some novel amino acid substitutions at key sites, which might represent interesting target sites for future mutagenesis experiments. Our data add to the increasing evidence that duplicate genes experience lower selective constraints and in some cases positive selection following gene duplication. Some of these observations are unexpected and may provide insights into the effect of caves on the evolution of color vision genes in fishes.

Use of the aquatic protozoa to formulate a community biotic index for an urban water system

Protozoan were collected from 16 stations in water system of Changde City (China) using the PFU method. Sampling programs were conduced on a yearly basis, with seasonal frequency at diverse sites in the water system and 488 species of protozoa was identified. At the same time, Water sampling from these stations was conducted and various water chemical parameters, including DO, COD, BOD5, NH3, TP, and Volatile Phenol, were analyzed. The aim of the research was, on one hand, using chemical method to take an investigation to the water pollution status of Changde City; on the other hand, using protozoan to make an evaluation to the water quality. With the chemical water parameters and protozoa data, a biotic index was derived for the investigated region. The species pollution value (SPV) of 469 protozoa species was established, and the community pollution value (CPV) calculated from SPV was used to evaluate water quality. The method of the biotic index was tested and the result showed that CPV calculated from SPV had a close correlation with the degree of water pollution (p < 0.00001). This indicated that the method of the biotic index is reliable. The water quality degrees divided by CPV were suggested. (c) 2004 Elsevier B.V. All rights reserved.

New data on the morphology and systematic status of Spinitectus petrowi and Spinitectus gigi (Nematoda : Cystidicolidae) parasitic in catfishes in central China

Two little-known nematode species of the genus Spinitectus Fourment, 1883, S. petrowi Belous, 1965 (prevalence 25%, intensity 1-8) and S. gigi Fujita, 1927 (prevalence 10%, intensity 2-3), were collected from the gastrointestinal tract of the yellow catfish, Pelteobagrus fulvidraco (Richardson), from Liangzihu Lake, Hubei Province, central China, in September of 2002. The light and scanning electron microscopical examination of this material, supplemented by a few museum specimens of S. gigi collected from the catfish Clarias fuscus (Lacepede) in southern China, made it possible to study in detail the morphology of these parasite species and to redescribe them. The first species, whose correct name is S. petrowi Belous, 1965, exhibits some morphological features (e.g., unusually short vestibule, shape of pseudolabia and of the left spicule) not found in most other congeners; a unique feature is the presence of peculiar pairs of transversely oriented peg-like cuticular spines with rounded ends on the ventral surface of the female tail. Spinitectus gigi was found to have 28-31 cuticular spines in the first ring, relatively long distances between the 2nd-7th rings of spines, and anterior rings divided into 2 sectors; the excretory pore is located at the level of the 4th ring of cuticular spines; males posses 4 pairs of preanal- and 6 pairs of postanal caudal papillae and a pair of small phasmids. Spinitectus bagri Wang, Wu et Yu, 1993 and S. wulingensis Yu et Wang, 1997 are considered junior synonyms of S. petrowi, whereas S. clariasi Ky, 1971, S. ophicephali Ky, 1971 and S. yuanjiangensis Wang, Wit et Yu, 1997 are regarded to be junior synonyms of S. gigi. Spinitectus petrowi was not previously reported from China.

Elasticity, band structure, and piezoelectricity of BexZn1-xO alloys

Lattice constants, elasticity, band structure and piezoelectricity of hexagonal wideband gap BexZn1-xO ternary alloys are calculatedusing firstprinciples methods. The alloys' lattice constants obey Vegard's law well. As Be concentration increases, the bulk modulus and Young's modulus of the alloys increase, whereas the piezoelectricity decreases. We predict that BexZn1-xO/GaN/substrate (x = 0.022) multilayer structure can be suitable for high-frequency surface acoustic wave device applications. Our calculated results are in good agreement with experimental data and other theoretical calculations. (c) 2008 Elsevier B.V. All rights reserved.

The effect of the AlxGa1-xN/AIN buffer layer on the properties of GaN/Si(111) film grown by NH3-MBE

We describe the growth of GaN on Si(111) substrates with AlxGa1-xN/AlN buffer layer by ammonia gas source molecular beam epitaxy (NH3-GSMBE). The influence of the AlN and AlxGa1-xN buffer layer thickness and the Al composition on the crack density of GaN has been investigated. It is found that the optimum thickness is 120 and 250 nm for AlN and AlxGa1-xN layers, respectively. The optimum Al composition is between 0.3 < x < 0.6. (c) 2005 Elsevier B.V. All rights reserved.