大鳞副泥鳅雄核发育单倍体胚胎发育的研究

雄核发育（ａｎｄｒｏｇｅｎｅｓｉｓ）系指卵子只依靠雄性原核进行发育的生殖方式。尽管已有川鲽（Ｐｌａｔｉｃｈｔｈｙｓｆｌｅｓｕｓ）（Ｐｕｒｄｏｍ，１９６９）、马苏大麻哈鱼（Ｏｎｃｏｈｙｃｈｕｓｍａｓｏｕ）（Ａｒａｉ等，１９７９）、虹鳟（Ｓａｌｍｏｇａ...

野鲮亚科口前室鱼类口唇及其相关结构形态学研究

口唇及其相关结构是野鲮亚科鱼类属级单元的主要分类依据。对我国野鲮亚科中具口前室鱼类类群的口唇及其相关结构形态学进行比较研究，结果显示：吻皮和下唇的形态差异以及吻皮与下唇、上颌与下唇、吻皮与上颌和下唇与下颌之间相互联结的差异，构成了口前室鱼类各类群的主要分类特征；口前室鱼类的口型可区分出４种基本式样。根据口前室鱼类口唇及其相关结构形态学特征，对口前室鱼类口型式样相似性以及其属级类群间的进化关系进行了讨论；进而对我国特有类群华缨鱼属Ｓｉｎｏｃｒｏｓｏｃｈｅｉｌｕｓ和盘唇鱼属Ｄｉｓｃｏｃｈｅｉｌｕｓ的系统分类地

中华双腔吸虫精子发生的超微结构研究

应用透射电镜技术，研究中华双腔吸虫（Ｄｉｃｒｏｃｏｅｌｉｕｍ ｃｈｉｎｅｓｉｓ Ｔａｎｇ ｅｔ Ｔａｎｇ １９７８）的精子发生， 并与其它复殖吸虫进行比较，提出了复殖吸虫精子发生的一般过程，结果显示它与大多数复殖吸虫 精子发生的超微结构相似，原始的精原细胞经过三次有丝分裂，两次减数分裂成为精细胞，它经过 分化、形态变化后成为成熟精子，精子形成共分为六个阶段，其中有以下首次报道的特征：（１）中 央胞质区的生长速度在开始时比鞭毛要快；（２）在鞭毛与中央胞质区融合前，线粒体的前端在中央 胞质区中有段时间比核更接

网湖似刺鳊鮈种群生长和死亡率研究

本文根据６６９尾标本，研究长江中游网湖小型经济鱼类似刺鳊的种群生长和死亡率，从理论推导证明，鱼类的生长拐点与其临界年龄是一致的，并据以对网湖似刺鳊等小型经济鱼类的合理渔业对策问题进行了初步分析讨论。

Development of predictive models for cement stabilized soils

Factors that affect the engineering properties of cement stabilized soils such as strength are discussed in this paper using data on these factors. The selected factors studied in this paper are initial soil water content, grain size distribution, organic matter content, binder dosage, age and curing temperature, which has been collated from a number of international deep mixing projects. Some resulting correlations from this data are discussed and presented. The concept of Artificial Neural Networks and its applicability in developing predictive models for deep mixed soils is presented and discussed using a subset of the collated data. The results from the neural network model were found to emulate the known trends and reasonable estimates of strength as a function of the selected variables were obtained. © 2012 American Society of Civil Engineers.

丝藻目的一新属——骈丝藻属

<正> 1976年6月至8月,中国科学院青藏高原综合科学考察队藏北分队对冈底斯山,念青唐古拉山以北,昆仑山以南的广大藏北地区进行了多学科的综合考察。我所陈宜瑜同志参加了这次考察,对该地区各种水体的水生生物进行了广泛地采集,在采得的标本中,藻类是十分丰富的。我们在鉴定该区振泉湖藻类标本时,发现一特殊类型的藻类。通过对液浸标本和固定染色标本的研究,确定它是绿藻门丝藻目的一新属。

Compression and tensile properties of self-reinforced poly(ethylene terephthalate)-composites

Tensile and compression properties of self-reinforced poly(ethylene terephthalate) (SrPET) composites has been investigated. SrPET composites or all-polymer composites have improved mechanical properties compared to the bulk polymer but with maintained recyclability. In contrast to traditional carbon/glass fibre reinforced composites, SrPET composites are very ductile, resulting in high failure strains without softening or catastrophic failure. In tension, the SrPET composites behave linear elastically until the fibre-matrix interface fails, at which point the stiffness starts decreasing. As the material is further strained, strain hardening occurs and the specimen finally fails at a global strain above 10%. In compression, the composite initially fails through fibre yielding, and at higher strains through fibre bending. The stress-strain response is reminiscent of an elastic-perfectly plastic material with a high strain to failure (typically over 10%). This indicates that SrPET composites are not only candidates as semi-structural composites but also as highly efficient energy absorbing materials. © 2012 Elsevier Ltd. All rights reserved.

Feeding rates affect heat shock protein levels in liver of larval white sturgeon (Acipenser transmontanus)

A two-week trial was conducted to study the effect of feeding rates on heat shock protein levels in larval white sturgeon. The larvae (30 day post hatch, 230 mg initial body weight) were fed a commercial feed (12.6% moisture, 49.5% crude protein. 20.7% Crude fat, and 8.6% ash) at 5, 15. or 25% body weight per clay (BW d(-1)). Liver heat shock proteins (Hsp) were measured before and after the larvae were subjected to a heat shock from 18 to 26 degrees C at 1 degrees C/15 min and maintained at 26 degrees C for 4 h thereafter. Before heat shock, larvae fed 5% BW d(-1) had significantly (P<0.05) lower final body weight, RNA/DNA ratio, whole body lipid and protein content, and Hsp60 and Hsp70 levels but higher protein efficiency ratio, and whole body moisture content than larvae fed the two higher feeding rates. Heat shock significantly induced Hsp60 and Hsp70 levels in the liver of all fish but they were lower in larvae fed the 5% than those fed 15 and 25% BW d(-1). Hsp70 level increased much more than Hsp60 after the heat shock Suggesting that Hsp70 is a more sensitive biomarker under our experimental conditions. (c) 2008 Elsevier B.V. All rights reserved.

Developmental toxicity and alteration of gene expression in zebrafish embryos exposed to PFOS

Perfluorooetanesulfonate (PFOS) is a persistent organic pollutant, the potential toxicity of which is causing great concern. In the present study, we employed zebrafish embryos to investigate the developmental toxicity of this compound. Four-hour post-fertilization (hpf) zebrafish embryos were exposed to 0.1, 0.5, 1, 3 and 5 mg/L PFOS. Hatching was delayed and hatching rates as well as larval survivorship, were significantly reduced after the embryos were exposed to 1, 3 and 5 mg/L PFOS until 132 hpf. The fry displayed gross developmental malformations, including epiboly deformities, hypopigmentation, yolk sac edema, tail and heart malformations and spinal curvature upon exposure to PFOS concentrations of I mg/L or greater. Growth (body length) was significantly reduced in the 3 and 5 mg/L PFOS-treated groups. To test whether developmental malformation was mediated via apoptosis, flow cytometry analysis of DNA content, acridine orange staining and TUNEL assay was used. These techniques indicated that more apoptotic cells were present in the PFOS-treated embryos than in the control embryos. Certain genes related to cell apoptosis, p53 and Bax, were both significantly up-regulated upon exposure to all the concentrations tested. In addition, we investigated the effects of PFOS on marker genes related to early thyroid development (hhex and pax8) and genes regulating the balance of androgens and estrogens (cyp19a and cyp19b). For thyroid development, the expression of hhex was significantly up-regulated at all concentrations tested, whereas pax8 expression was significantly up-regulated only upon exposure to lower concentrations of PFOS (0.1, 0.5, 1 mg/L). The expression of cyp19a and of cyp19b was significantly down-regulated at all exposure concentrations. The overall results indicated that zebrafish embryos constitute a reliable model for testing the developmental toxicity of PFOS, and the gene expression patterns in the embryos were able to reveal some potential mechanisms of developmental toxicity. (C) 2008 Elsevier Inc. All rights reserved.

Isolation and characterization of polymorphic microsatellites in a sex-reversal fish, rice field eel (Monopterus albus)

The rice field eel (Monopterus albus) is a fish of economic importance in China and some Asian countries. From a (GT)(n)-enriched genomic library, 30 microsatellites were developed by employing the fast isolation by AFLP of sequences containing repeats (FIASCO) protocol. Thirteen loci exhibited polymorphism with two to 13 alleles (mean 7.9 alleles/locus) in a test population and observed heterozygosity ranged from 0.3125 to 0.9688 (mean 0.7140). These loci should provide sufficient level of genetic variation to study the fine-scale population structure and reproductive ecology of the species.

Identification of one intron loss and phylogenetic evolution of Dfak gene in the Drosophila melanogaster species group

Intron loss and its evolutionary significance have been noted in Drosophila. The current study provides another example of intron loss within a single-copy Dfak gene in Drosophila. By using polymerase chain reaction (PCR), we amplified about 1.3 kb fragment spanning intron 5-10, located in the position of Tyr kinase (TyK) domain of Dfak gene from Drosophila melanogaster species group, and observed size difference among the amplified DNA fragments from different species. Further sequencing analysis revealed that D. melanogaster and D. simulans deleted an about 60 bp of DNA fragment relative to other 7 Drosophila species, such as D. elegans, D. ficusphila, D. biarmipes, D. takahashii, D. jambulina, D. prostipennis and D. pseudoobscura, and the deleted fragment located precisely in the position of one intron. The data suggested that intron loss might have occurred in the Dfak gene evolutionary process of D. melanogaster and D. simulans of Drosophila melanogaster species group. In addition, the constructed phylogenetic tree based on the Dfak TyK domains clearly revealed the evolutionary relationships between subgroups of Drosophila melanogaster species group, and the intron loss identified from D. melanogaster and D. simulans provides a unique diagnostic tool for taxonomic classification of the melanogaster subgroup from other group of genus Drosophila.

Some nematodes of fishes from central China, with the redescription of Procamallanus (Spirocamallanus)fulvidraconis (Camallanidae)

The present paper comprises a systematic survey of nematodes based on helminthological examinations of 176 specimens of freshwater fishes, belonging to 22 species, from central China (mostly lakes in Hubei Province) collected during the autumn of 2001. The following six species were recorded: Procamallanus (Spirocamallanus) fulvidraconis Li, 1935, Camallanus cotti Fujita, 1927, Dentiphilometra monopteri Moravec et Wang, 2002, Pingus sinensis Hsu, 1933, Proleptinae gen. sp. larv., and Eustrongylides sp. larv. Data on their morphology, morphological variability, host range, prevalence, intensity and distribution are provided. SEM studies of P. fulvidraconis and larval Physalopterinae, used for the first time in these species, revealed some additional morphological details and made it possible to redescribe the former. In contrast to the existing description of P. fulvidraconis, this species was found to possess two spicules and a V-shaped gubernaculum with unequal arms (originally mistaken for the left spicule), as well as deirids, whose location can be considered an important taxonomic feature. Larvae of the Physalopterinae have not previously been reported from fishes in China. The finding of larval Eustrongylides in Paramisgurnus dabryanus represents a new host record. All but one nematode species from this zoogeographically interesting region are briefly described and illustrated.

Structure-function analysis of the inverted terminal repeats of the Sleeping Beauty transposon

Translocation of Sleeping Beauty (SB) transposon requires specific binding of SB transposase to inverted terminal repeats (ITRs) of about 230 bp at each end of the transposon, which is followed by a cut-and-paste transfer of the transposon into a target DNA sequence. The ITRs contain two imperfect direct repeats (DRs) of about 32 bp. The outer DRs are at the extreme ends of the transposon whereas the inner DRs are located inside the transposon, 165-166 bp from the outer DRs. Here we investigated the roles of the DR elements in transposition. Although there is a core transposase-binding sequence common to all of the DRs, additional adjacent sequences are required for transposition and these sequences vary in the different DRs. As a result, SB transposase binds less tightly to the outer DRs than to the inner DRs. Two DRs are required in each ITR for transposition but they are not interchangeable for efficient transposition. Each DR appears to have a distinctive role in transposition. The spacing and sequence between the DR elements in an ITR affect transposition rates, suggesting a constrained geometry is involved in the interactions of SB transposase molecules in order to achieve precise mobilization. Transposons are flanked by TA dinucleotide base-pairs that are important for excision; elimination of the TA motif on one side of the transposon significantly reduces transposition while loss of TAs on both flanks of the transposon abolishes transposition. These findings have led to the construction of a more advanced transposon that should be useful in gene transfer and insertional mutagenesis in vertebrates. (C) 2002 Elsevier Science Ltd. All rights reserved.