鲤科鱼类结缔组织生长因子基因变异和分子进化

结缔组织生长因子(CTGF)在细胞生长、分化和凋亡及个体生长发育中具有重要的调控作用.研究CTGF基因在不同鱼类中的变异及进化,对于理解物种分化和基因差异具有重要意义.文中通过PCR扩增、克隆和测序,获得了19种鲤科鱼类(Cyprinidae)CTGF基因序列,并重建了鲤科鱼类系统发育关系,用于估计各分支的进化速率.以鳉科(Cyprinodontidae)的青鳉(Oryzias latipes)作为外类群,系统树均以较高的节点支持率支持鲤科鱼类中雅罗鱼系(Leuciscini)和鲃系(Barbini)的划

Janibacter sp.对活性污泥反应器中二苯并呋喃降解的强化作用及其遗传学分析

二苯并呋喃(DF)是研究二英类化合物生物降解的模式化合物之一。本文报道了一种降解菌Janibacter sp.对活性污泥降解二苯并呋喃的强化作用,以及对其降解基因的分析结果。向反应器中添加5%的降解菌,与活性污泥共同作用,可在48h内将约56mg/L剂量的DF几乎完全降解,提高降解率28%以上。利用PCR方法,克隆和测序分析证明有DF降解基因丛的存在,并且发现以丰富培养基在高温下培养可去除该基因丛;丢失该基因丛的突变株同时失去利用DF作为唯一碳源进行生长的能力,显示其很可能位于一个大质粒上。

月湖底栖动物的空间格局及其对水草可恢复区的指示

底质适宜是富营养湖泊恢复沉水植物(水草)的重要前提。大型底栖动物可综合指示底质的污染程度,于2002~2003年在武汉月湖开展了底栖动物水平分布对水草可恢复区指示作用的研究。首先通过月湖底栖动物与环境的相关分析,选择颤蚓科寡毛类作为底质营养状况的指示类群,然后利用同类湖泊群颤蚓与水草数据分析阈值,初步确定颤蚓密度≤100 ind/m2的底质适合水草生长,最后绘制月湖颤蚓分布的水平等值线,显示水草恢复的合适区域。在此基础上构建了应用底栖动物空间格局指示水草恢复区的技术原理框架。

武汉城市湖泊水环境现状及综合整治途径

近十几年来 ,随着人口的增长 ,现代工业和农业的发展 ,湖泊的老化过程受到人类活动的影响而大大加速。过量营养物质的富集 ,使水体产生了一系列的变化。结合武汉市湖泊水环境现状分析 ,指出了武汉市湖泊当前存在的三个突出的问题 ,即污染严重、湖泊萎缩和水量锐减、湖泊生态系统遭破坏。在此基础上 ,提出了一套适合武汉湖泊整治的综合途径 ,具体包括以下四个方面的内容 :①管理组织模式与政策法规 ;②提高工程的科技含量 ,重点实施湖泊生态修复工程 ;③发展水经济 ,形成新的产业增长点 ;④加强水文化建设 ,提高市民的环

岱海水质咸化过程中若干生态因子的变化

在1996年夏季对岱海的综合调查基础上，结合自50年代以来关于岱海的地理学、水文学和水生生物学资料，对岱海水质咸化中的若干生态因子进行了比较分析，结果表明：目前岱海pH值为933，这已经接近生物适应范围的最上限；总碱度也逐年增长，而且增长极为明显；氯离子的含量也已经远远超过了1000mg/L的极限指标。上述变化清晰地说明，岱海的水质咸化过程正在加强。同时，钙镁比率越来越失调，水的硬度也不断增加，这些变化对渔业生产十分不利。

Serum concentrations of gonadotropins and steroid hormones of Neophocaena phocaenoides asiaeorientalis in middle and lower regions of the Yangtze River

As a relatively isolated and unique freshwater population, the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is the most endangered subpopulation of this species. The objective of this study was to improve our understanding of their reproductive endocrinology by measuring (radioimmunoassay) serum concentrations of FSH, LH, estradiol (E-2), progesterone (P-4) and testosterone (T-2) in free-ranging animals. Blood samples were collected from 66 Yangtze finless porpoises (41 males and 25 females) captured in the middle and lower reaches of the Yangtze River. Based on significant variation of serum T-2 concentrations in males with body length (BL) > 138 cm, we inferred that they were mature; in these animals, there were significant seasonal variations in serum T-2 concentrations, with the highest concentrations in March and April (502.0 +/- 319.8 ng/dL, mean +/- S.D.) and the lowest in December (79.4 +/- 83.2 ng/dL). Serum T-2 concentrations positively correlated with serum concentrations of LH and weakly correlated with serum concentrations of E-2, whereas there was a significant negative correlation between serum LH and FSH concentrations in males > 138 cm. The smallest apparently pregnant female porpoise had a BL of 130 cm. Serum P-4 concentrations ranged from 13.2 to 112.4 ng/mL (43.9 +/- 28.3 ng/mL) in pregnant females, and fluctuated under 1.0 ng/mL in non-pregnant females with BL > 130 cm. Serum LH concentrations were significantly higher in non-pregnant females > 130 cm versus those females < 130 cm. To our knowledge, this is the first study of endocrine-related maturity and seasonal breeding characteristics of the Yangtze finless porpoise. (c) 2006 Elsevier Inc. All rights reserved.

Early ontogeny of Ancherythroculter nigrocauda and effects of delayed first feeding on larvae

Development of embryos and larvae in Ancherythroculter nigrocauda Yih et Woo (1964) and effects of delayed first feeding on larvae were observed after artificial fertilization. The fertilized eggs were incubated at an average temperature of 26.5 degrees C (range: 25.7-27) and the larvae reared at temperatures ranging from 21.8 to 28 degrees C. First cleavage was at 50 min, epiboly began at 7 h 5 min, heartbeat reached 72 per min at 24 h 40 min and hatching occurred at 43 h 15 min after insemination. Mean total length of newly hatched larvae was 4.04 +/- 0.03 mm (n = 15). A one-chambered gas bladder was observed at 70 h 50 min, two chambers occurred at 15 days, and scales appeared approximately 30 days after hatching. Larvae began to feed exogenously at day 4 post-hatch at an average temperature of 24 degrees C. Food deprivation resulted in a progressive atrophy of skeletal muscle fibres, deterioration of the larval digestive system and cessation of organ differentiation. Larval growth under food deprivation was significantly affected by the time of first exogenous feeding. Starved larvae began to shrink, with negative growth from day 6 post-hatch. The point of no return (PNR) was reached at day 11 after hatching. Mortality of starved larvae increased sharply from day 12 after hatching.

Studies on the biology of Chaoborus flavicans (Meigen) (Diptera : Chaoboridae) in a fish-free eutrophic pond, Japan

Population dynamics of Chaoborus flavicans larvae of various instars was studied from November 1986 to December 1987 in a eutrophic, fish-free pond, Japan. First and 2nd instar larvae were observed from late April to late October, indicating a reproductive period of about half a year. C. flavicans overwintered in the 4th instar larvae. In water column samples, total density of all instars was 680-23 680 m(-2), and pupal density 0-2 600 m(-2); larvae of the Ist, 2nd, and 3rd instars showed 5-6 density peaks in 1987, suggesting that 5-6 generations occur during a year (peaks of the 4th instar larvae were not clear, probably due to their longer development than those of younger instars). In sediment samples, no Ist and 2nd instar larvae were found, 3rd instar larvae were found occasionally but density of the 4th instar larvae was 280-18 600 m(-2), and pupal density varied between 0-502 m(-2). Fouth instar larvae accumulated in sediment in the cold season and in the water column in the warm season; high temperature and low oxygen concentration were the most important factors limiting the distribution of larvae in the sediment in summer in the NIES pond. The dry weight of total C. flavicans larvae was 0.08-4.2 g m(-2) in sediment samples and 24-599 mu g l(-1) (0.10-2.40 g m(-2)) in water column samples. Comparisons of maximum densities in the NIES pond in different years and in waters of different trophic status show that density is generally higher in eutrophic than in oligotrophic habitats.

Investigation of mode radiation loss for microdisk resonators with pedestals by FDTD technique

Mode radiation loss for microdisk resonators with pedestals is investigated by three-dimensional (3D) finite-difference time-domain (FDTD) technique. For the microdisk with a radius of 1 mu m, a thickness of 0.2 mu m, and a refractive index of 3.4, on a pedestal with a refractive index of 3.17, the mode quality (Q) factor of the whispering-gallery mode (WGM) quasi-TE7,1 first increases with the increase of the radius of the pedestal, and then quickly decreases as the radius is larger than 0.75 mu m. The mode radiation loss is mainly the vertical radiation loss induced by the mode coupling between the WGM and vertical radiation mode in the pedestal, instead of the scattering loss around the perimeter of the round pedestal. The WG M can keep the high Q factor when the mode coupling is forbidden.

Mode analysis and Q-factor enhancement due to mode coupling in rectangular resonators

Modes in rectangular resonators are analyzed and classified according to symmetry properties, and quality factor (Q-factor) enhancement due to mode coupling is observed. In the analysis, mode numbers p and q are used to denote the number of wave nodes in the direction of two orthogonal sides. The even and odd mode numbers correspond to symmetric and antisymmetric field distribution relative to the midlines of sides, respectively. Thus, the modes in a rectangle resonator can be divided into four classes according to the parity of p and q. Mode coupling between modes of different classes is forbidden; however, anti-crossing mode coupling between the modes in the same class exists and results in new modes due to the combination of the coupled modes. One of the combined modes has very low power loss and high Q-factor based on far-field emission of the analytical field distribution, which agrees well with the numerical results of the finite-difference time-domain (FDTD) simulation. Both the analytical and FDTD results show that the Q-factors of the high Q-factor combined modes are over one order larger than those of the original modes. Furthermore, the general condition required to achieve high-Q modes in the rectangular resonator is given based on the analytical solution.

Electrolyte electroreflectance spectroscopy studies on the interfacial behavior of the near-surface In0.15Ga0.85As/GaAs quantum well electrode vertical bar non-aqueous electrolyte

Electrolyte electroreflectance spectra of the near-surface strained-layer In0.15Ga0.85As/GaAs double single-quantum-well electrode have been studied at different biases in non-aqueous solutions of ferrocene and acetylferrocene. The optical transitions, the Franz-Keldysh oscillations (FKOs) and the quantum confined Stark effects (QCSE) of In0.15Ga0.85As/GaAs quantum well electrodes are analyzed. Electric field strengths at the In0.15Ga0.85As/GaAs interface are calculated in both solutions by a fast Fourier transform analysis of FKOs. A dip is exhibited in the electric field strength versus bias (from 0 to 1.2 V) curve in ferrocene solution. A model concerning the interfacial tunneling transfer of electrons is used to explain the behavior of the electric field. (C) 2001 Elsevier Science B.V. All rights reserved.