白鲫(♀)×红鲫(♂)异源四倍体鱼的倍性操作及其生殖力的研究

采用热休克调控技术诱导出103尾第一代白鲫（♀）×红鲫（）异源四倍体鱼，并对其生殖力进行了研究。1或2龄的四倍体雄鱼能产生精子，而雌鱼不能产生正常的卵。将异源四倍体雄鱼与二倍体白鲫雌鱼交配产生倍间三倍体鱼，染色体检查证明是整三倍体（3N＝150），但其受精率很低（11．4—51．3％，平均32．4％）．网箱养殖结果表明，倍间三倍体白鲫的生长速度比白鲫快30％以上，雌雄均不育．并用冷休克处理回收异源四倍体4N（）×白鲫2N（♀）受精卵的第二极体产生了新的四倍体鱼．文中还对第一代异源四倍体鱼的批量生产、生殖能

武汉东湖颗粒悬浮物的结构与元素组成

本研究于１９８９－１９９０对武汉东湖营养水平不同的二个湖区的颗粒悬浮物的干物质结构和元素组成进行了分析．综合平均值表明，浮游动物的现存量约为浮游植物的１／４，浮游动物群落以小型的原生动物和轮虫占优势．从年平均值来看，浮游生物的干重占颗粒悬浮物干物质的２．５—７．６％，浮游生物碳量占颗粒悬浮物碳量的４．０—９．８％；颗粒悬浮物的碳／氮比与一般浮游植物的比值相似，但明显大于多数浮游动物；颗粒悬浮物的碳与干物重之比约为一般浮游生物的３／４；颗粒悬浮物的灰分含量约为４５％，显著高于除硅藻以外的其它浮游生物。从数量

生活周期毒性试验动物─—方形网纹溞的生物学

在实验室条件下研究方形网纹的生物学。试验时水温２５±１℃，饲以斜生栅藻。初生幼体平均体长０．４０ｍｍ，第１成龄０．９６ｍｍ，最大体长可达１．４５ｍｍ，体长增长（１＿ｔ，单位ｍｍ）与年龄（ｔ，ｄ）的关系可以表达为１＿ｔ＝１．４３－ｅ￣（－０．２６８ｔ），平均寿命２２．７３（１７．１０－２５．００）ｄ，其中包括３个幼龄和１３个成龄。在３．９１ｄ达到性成熟。７ｄ内生殖３胎，产仔４０（１９－４７）个。一生生殖２２２．０个幼体，平均每胎１８．５（４．８－２３．６）个。生殖量最大出现在第６成龄。这时的年龄１１．０５ｄ

淡水生态系统中的若干生物多样性问题

<正> 淡水生态系统,包括河流和湖泊等内陆水体,较陆地生态系统和海洋生态系统更具封闭性,自我反馈能力较弱,稳定性较低,显得特别脆弱。然而淡水资源又是人类赖以生存的最为重要的资源之一,它关系到饮水、灌溉、航运、发电、渔业、旅游和工业、生活用水等重大问题。近几十年来。由于森林砍伐造成的水土流失,由于围湖造田造成的水域面积缩减,

中华鲟、白鲟组织生化成分分析初报

<正> 中华鲟(Acipenser sinensis Cray)隶属鲟形目、鲟科,在生态类群中属河海洄游鱼类,主要分布于我国长江,也见于渤海(烟台)、黄河下游、钱塘江、闽江及珠江等水域。白鲟(Psephurus gladius Martens)隶属鲟形目、白鲟科,也是一种河海洄游性鱼类,主要分布在长江水系中,自四川宜宾至江苏崇明,有时见于大型湖泊(如洞庭湖)。对于这两种我国特有、珍稀、大型的经济鱼类的形态,解剖、地理分布及生态等方面许多研究者曾作过大量的工作,积累了系统的资料(张春霖1928、伍献文192

ChESS - Quick and robust detection of chess-board features

Localization of chess-board vertices is a common task in computer vision, underpinning many applications, but relatively little work focusses on designing a specific feature detector that is fast, accurate and robust. In this paper the 'Chess-board Extraction by Subtraction and Summation' (ChESS) feature detector, designed to exclusively respond to chess-board vertices, is presented. The method proposed is robust against noise, poor lighting and poor contrast, requires no prior knowledge of the extent of the chess-board pattern, is computationally very efficient, and provides a strength measure of detected features. Such a detector has significant application both in the key field of camera calibration, as well as in structured light 3D reconstruction. Evidence is presented showing its superior robustness, accuracy, and efficiency in comparison to other commonly used detectors, including Harris & Stephens and SUSAN, both under simulation and in experimental 3D reconstruction of flat plate and cylindrical objects. © 2013 Elsevier Inc. All rights reserved.

多子小瓜虫的形态、生活史及其防治方法和一新种的描述

<正> 一、绪言小瓜虫是一种身体比较大,肉眼能见的原生动物,寄生在各种淡水鱼的上皮组织和鳃丝组织中,剥取寄主的上皮细胞和红血球为生。同时,由于它在组织中不停的活动和钻营的结果,上皮组织引起病态的浮肿,形成白色突出的小点,故有“白点”病之称。这种病,目前在我国淡水养鱼事业中已成为主要的危险病害之一。它的爆发流行,往往使成千成万的鱼种在几天之内死亡;用作春季产卵孵化的亲鲤,由于它的侵袭,以致不能完成鲤鱼苗的生产计划。金鱼和热带鱼的饲养者对小瓜虫的威胁体会更深,多年很费

Performance of joints in reinforced concrete slabs for two-way spanning action

A series of tests on filigree slab joints was performed with the aim of assessing whether such joints can be reliably used in the construction of two-way spanning reinforced concrete slabs. The test results were compared with code requirements. Adequate joint performance is shown to be achievable when the joints are appropriately detailed. Further research is recommended for the formulation of a more generic understanding when the design parameters are varied from those studied in this work.

Localization and tracking of phonating finless porpoises using towed stereo acoustic data-loggers

Cetaceans produce sound signals frequently. Usually, acoustic localization of cetaceans was made by cable hydrophone arrays and multichannel recording systems. In this study, a simple and relatively inexpensive towed acoustic system consisting of two miniature stereo acoustic data-loggers is described for localization and tracking of finless porpoises in a mobile survey. Among 204 porpoises detected acoustically, 34 individuals (similar to 17%) were localized, and 4 of the 34 localized individuals were tracked. The accuracy of the localization is considered to be fairly high, as the upper bounds of relative distance errors were less than 41% within 173 m. With the location information, source levels of finless porpoise clicks were estimated to range from 180 to 209 dB re 1 mu Pa pp at 1 m with an average of 197 dB (N=34), which is over 20 dB higher than that estimated previously from animals in enclosed waters. For the four tracked porpoises, two-dimensional swimming trajectories relative to the moving survey boat, absolute swimming speed, and absolute heading direction are deduced by assuming the animal movements are straight and at constant speed in the segment between two consecutive locations.

Structure, organization and expression of common carp (Cyprinus carpio L.) NKEF-B gene

Natural killer (NK) cell enhancing factor (NKEF) belongs to the newly defined peroxiredoxin (Prx) family. Its functions are to enhance NK cell cytotoxicity and to protect DNA and proteins from oxidative damage. In this study, a partial cDNA sequence of carp NKEF-B was isolated from thymus cDNA library. Subsequently, the full-length cDNA of carp NKEF-B was obtained by means of 3' and 5' RACE, respectively. The full-length cDNA of carp NKEF-B was 1022 bp, consisting of a 73 bp 5'-terminal untranslated region (UTR), a 355 bp T-terminal UTR, and a 594 bp open reading frame coding for a protein of 197 amino acids. Carp NKEF-B contained two consensus Val-Cys-Pro (VCP) motifs and three consensus cysteine (Cys-51, Cys-70 and Cys-172) residues. Sequence comparison showed that the deduced amino acid sequence of carp NKEF-B had an overall similarity of 74-96% to that of other species homologues. Phylogenetic analysis revealed that carp NKEF-B forms a cluster with other known teleost NKEF-Bs. Then, by PCR we obtained a 5.1 -k long genomic DNA of carp NKEF-B containing six exons and five introns. Realtime RT-PCR results showed that carp NKEF-B gene was predominantly detected in kidney and head kidney under un-infected conditions. Whereas under SVCV-infection condition, the expression of NKEF-B gene was significantly increased in blood cells, gill, intestine and spleen, but maintained in liver, and decreased significantly in kidney and head kidney. Finally, the rNKEF-B was constructed and expressed in Escherichia coli. By using an antibody against carp rNKEF-B, immunohistochemical study further indicated that NKEF-B positive cells are mainly some RBCs and a few epithelial cells in gill and intestine, and that under SVCV-infection condition, these positive cells or positive products in their cytoplasm were mainly increased in gill and spleen sections of carp. The results obtained in the present study will help to understand the function of NKEF-B in teleost innate immunity. (C) 2008 Elsevier Ltd. All rights reserved.

Reduced swimming abilities in fast-growing transgenic common carp Cyprinus carpio associated with their morphological variations

Critical swimming speeds (U-crit) and morphological characters were compared between the F-4 generation of GH-transgenic common carp Cyprinus carpio and the non-transgenic controls. Transgenic fish displayed a mean absolute U-crit value 22.3% lower than the controls. Principal component analysis identified variations in body shape, with transgenic fish having significantly deeper head, longer caudal length of the dorsal region, longer standard length (L-S) and shallower body and caudal region, and shorter caudal length of the ventral region. Swimming speeds were related to the combination of deeper body and caudal region, longer caudal length of the ventral region, shallower head depth, shorter caudal length of dorsal region and L-S. These findings suggest that morphological variations which are poorly suited to produce maximum thrust and minimum drag in GH-transgenic C. carpio may be responsible for their lower swimming abilities in comparison with non-transgenic controls.

Diel isotopic fluctuation in surface seston and its physiological and ecological implications

We reported diet fluctuation in isotopic composition of surface seston from two connected lakes in China, oligotrophic Lake Fuxian and eutrophic Lake Xingyun. The decrease in nighttime and the increase in daytime of isotope signatures of seston might be attributed to the light-dependent balance between the photosynthesis and the respiration of phytoplankton and to the changes in the species composition and the relative abundance of phytoplankton functional groups at the water's surface in diel growth. The relatively high isotopic signatures and the large-extent diel fluctuation of phytoplankton in the eutrophic lake could be due to utilization of heavy-isotope-enriched inorganic sources and the high primary productivity. Extent of diel fluctuation in delta C-13 and delta N-15 of phytoplankton were relatively small compared with the isotopic enrichment per trophic transfer and thus might have negligible effect on the source identification and the trophic evaluation of consumers.

Non-destructive optical characterization of phase separation in bulk heterojunction organic photovoltaic cells

The dithiophene donor-acceptor copolymers that are bridged either with carbon (C-PCPDTBT) or silicon atoms (Si-PCPDTBT) belong to a promising family of materials for use in photoactive layers for organic photovoltaic cells (OPVs). In this work, we implement the non-destructive Spectroscopic Ellipsometry technique in the near infrared to the far ultraviolet spectral region in combination with advanced theoretical modeling to investigate the vertical distribution of the C-PCPDTBT and Si-PCPDTBT polymer and fullerene ([6,6]-phenyl C71-butyric acid methyl ester - PC70BM) phases in the blend, as well as the effect of the polymer-to-fullerene ratio on the distribution mechanism. It was found that the C-PCPDTBT:PC70BM blends have donor-enriched top regions and acceptor-enriched bottom regions, whereas the donor and acceptor phases are more homogeneously intermixed in the Si-PCPDTBT:PC70BM blends. We suggest that the chemical incompatibility of the two phases as expressed by the difference in their surface energy, may be a key element in promoting the segregation of the lower surface phase to the top region of the photoactive layer. We found that the increase of the photoactive layer thickness reduces the polymer enrichment at the cathode, producing a more homogeneous phase distribution of donor and acceptor in the bulk that leads to the increase of the OPV efficiency. © 2014 Elsevier B.V.