Growth-independent effects of a fluctuating thermal regime on the life-history traits of the Japanese medaka (Oryzias latipes)

Abstract –  Temperature fluctuation has been shown to affect somatic growth rates and metabolic functions of fish, but little is known about the effects of fluctuating temperatures on life-history traits. We examined these effects on female Japanese medaka ( Oryzias latipes ) reared from hatch to maturity at two mean temperatures (27 and 30 °C) with diel temperatures either held constant or allowed to fluctuate ±5 °C. Feeding regimes were manipulated to equilibrate medaka growth rates in all treatments. Age and length at maturity decreased as a result of thermal fluctuation, whereas there was no effect of temperature fluctuation on the proportion of fish attaining maturity or on the number of eggs produced by a mature female. We hypothesise that short-term high temperatures associated with temperature fluctuation decreases development time, whereas reduced energy conversion efficiency at higher temperatures does not allow for increased egg production.     

病毒感染过程中青鳉irf2基因过表达的双面性

为了探究干扰素调节因子2 (interferon regulatory factor,IRF2)如何通过调控干扰素(IFN)表达影响鱼类的免疫,实验从青鳉中克隆了irf2 (Olirf2),发现该基因在青鳉各个组织中均有表达;将构建的真核表达载体pTol2/CMV-IRF2/IE1-pr转染到胖头鱥肌肉细胞系(FHM)后,发现瞬时过表达Olirf2能够显著促进鲤春病毒血症病毒(spring viremia of carp virus,SVCV)的复制,并抑制抗病毒相关基因mx1、ifn和irf3的表达。进一步通过双荧光素报告系统发现,Olirf2能够显著抑制NF-κB和ISRE的活性,说明Olirf2可能通过抑制细胞的天然免疫应答进而促进病毒的增殖。然而持续过表达Olirf2则增强了细胞的抗病毒能力,同时促进干扰素相关基因mx1、ifn和irf3的表达。因此,Olirf2基于表达的持续时间不同而具有抗病毒或者促病毒的双面效果。实验通过研究Olirf2在抗病毒信号通路中发挥的作用,为通过基因编辑或者转基因手段来构建抗病毒的鱼类提供了理论基础。     

Embryonic stem cells in fish: current status and perspectives

Totipotent embryonic stem (ES) cells represent a bridge that links in vitro and in vivo manipulations of animal genomes and have enormous potential for genetic engineering of livestock. We have recently established feeder cell-free conditions for culturing cells of midblastula embryos (MBE) of the medaka (Oryzias latipes) and obtained several stable cell lines that show all features of mouse ES cells in vitro. One of these lines, MES1, has been demonstrated to retain a diploid karyotype and can be induced to differentiate into various cell types in vitro. Upon microinjection into albino host blastulae, MES1 cells are able to form pigmented chimeras. Genotype-specific PCR analysis revealed that 90% of host blastulae transplanted with MES1 cells developed into chimeric fry. This high frequency was not compromised by cryostorage or DNA transfection of the donor cells. Transplantation of genetically labelled MES1 cells revealed a wide contribution to numerous organs derived from all three germ layers and differentiation into various types of functional cells. These ES properties of MES1 line was not abolished by stable gene transfer and long-term selection. Thus MES1 cells may represent a first promising cellular vehicle for the production of genetically modified fish. The genetic background has been found to have a profound effect on the efficacy of ES cell derivation and of chimera formation.     

Fuzzy neural network model for habitat prediction and HEP for habitat quality estimation focusing on Japanese medaka (Oryzias latipes) in agricultural canals

In the field of agriculture, development of evaluation techniques for environmental changes is urgently required for the purpose of finding a balance between growth in agricultural productivity and environmental considerations. The habitat evaluation procedures (HEP) constitute one technique for habitat assessment. While HEP is widely applied to estimate both habitat quality and quantity in an environment, it appears to be necessary to develop an accurate habitat prediction model in order to evaluate environments precisely. In fact, habitat selection by fish is affected by complicated interaction between multiple environmental factors, which makes it difficult to relate physical environments to habitat preference. In the present study, we utilize artificial neural networks (ANNs), which are commonly applied to model complex systems, to predict the habitat selection of Japanese medaka (Oryzias latipes) in agricultural canals. Considering the essential vagueness of fish behavior, fuzzy membership functions are introduced into the input layer, which advances ANN to fuzzy neural network (FNN). In addition, symmetric triangular fuzzy numbers are employed to account for uncertainty in measurement errors and dispersions of physical environment. The FNN model precisely predicts the habitat preference of Japanese medaka in an agricultural canal, and the results show a good agreement between the calculated and observed habitat suitability indices (HSI). Finally, the habitat quality of two different reaches at the same point in time is compared using HEP, with a view of suitable habitat for Japanese medaka.     

Levels of Vitellogenin in Male Japanese Medaka (Oryzias latipes) Exposed to the Chemotherapeutics: Oxytetracycline,Romet-30®, and Copper Sulfate

ABSTRACT

Japanese medaka (Oryzias latipes) were exposed to oxytetracycline and Romet-30^® at daily doses via feed of 0.06 mg, 0.11 mg, and 0.28 mg per gram body weight for 11 days, and at daily doses of 0.05 mg, 0.10 mg, and 0.15 mg per gram body weight for 5 days, respectively. In addition, fish were exposed to copper sulfate in their aquaria water at 1.85 mg/L for 1 h each day (over a span of 1 day, 7 consecutive days, or 1 day in every 3 to 5 days for a total of seven doses). Vitellogenin levels were measured in fish using a sandwich enzyme-linked immunosorbent assay (ELISA). Vitellogenin levels were not induced from exposure to either oxytetracycline or Romet-30® (P > 0.05); however, copper sulfate for 1 h on 1 day showed a decrease in vitellogenin from the control fish and other treatment groups (P = 0.007). Under these test conditions, oxytetracycline, Romet-30, and copper sulfate were not found to act in medaka as estrogenic compounds by inducing vitellogenin.     

外圆柱沟槽对环隙内波动涡流的影响

采用CFD数值计算方法对同心圆柱环隙内的波动涡流进行了数值模拟,根据PIV试验结果验证了数值计算方法的可靠性.重点研究了光壁模型和沟槽数量为9的2个模型环隙内的流场分布以及波动涡流的波动特性,对比分析了2种模型周向的流场分布,计算了泰勒涡的轴向尺寸及其轴向振幅,通过对比2种模型在R-Z平面上的径向速度分布,讨论了沟槽对环隙内流体的外射流作用的影响,分析了沟槽区域的流动特征以及出现的二次流现象.研究结果表明:沟槽的存在显著改变了环隙内的流场分布以及波动涡流的波动特性,沟槽区域形成的旋涡流动促进了沟槽内流体与环隙内流体的相互作用,加剧了环隙内的流动不稳定性.     

波式潜流人工湿地基质与污水磷素去除关系研究

通过分析测试研究了波式潜流人工湿地(WavySubsurfaceFlowConstructedWetland,简称W-SFCW)运行期间基质的磷素沉积量,以便解析不同人工湿地基质对于污水磷素去除的关系。试验污水为经短时厌氧预处理的化粪池污水,并在相同试验条件下与水平潜流人工湿地(HorizontalSubsurfaceflowConstructedWetland,简称SFCW)进行了对比分析。在近2年的人工湿地连续试验期间,分别于2003年11月、2004年5月和2004年11月测定了两种人工湿地基质的磷素沉积量。结果表明,随着人工湿地运行时间的延续,污水中的磷从以人工湿地基质吸附为主,逐渐变成以难溶性磷酸盐的沉积为主;为了人工湿地持续高效地去除TP,用释放Ca2 等金属离子的基质能够促进不溶磷酸盐的沉积;W-SFCW由于使所有水流不断与土壤层、砾石层和豆石层反复接触,生成难溶性磷酸盐的几率大大高于SFCW,能够比SFCW更加显著地促进磷沉积。     

波式潜流人工湿地处理生活污水的试验研究

提出了一种新型潜流构造湿地—波式潜流人工湿地(WavySubsurfaceFlowConstructedWetland,简称W-SFCW)并进行了在相同试验条件下与水平潜流人工湿地(HorizontalSubsurfaceflowConstructedWetland,简称SFCW)进行对比试验。结果表明,W-SFCW在污染物去除方面明显优于SFCW,在相同试验条件下W-SFCW出水COD、NH4+-N和TP分别为47.1、10.4和0.42mg·L-1,去除率分别比SFCW提高8.2%、13.1%和6.6%;但W-SFCW系统水流阻力大于SFCW系统,在本试验条件下W-SFCW的湿地床体的水头损失220mm,而SFCW水头损失70mm;W-SFCW及SFCW在冬季运行期间COD、NH4+-N去除率受环境温度影响明显,但未出现恶化现象;磷去除在低温期间几乎不受影响。     

钒对日本青鳉的急性毒性及与镍·镉的毒性比较

[目的]研究钒对水生生物毒性强弱,为制定含钒废水排放标准提供科学依据。[方法]以日本青鳉为受试生物,采用半静止生物测试法,比较研究了V（Ⅴ）和Ni2＋、Cd2＋对日本青鳉的急性毒性。[结果]V（Ⅴ）、Ni2＋和Cd2＋对日本青鳉的96 hLC50分别为2.73、6.02和0.22 mg/L;3种重金属毒性强度依次为Cd2＋〉V（Ⅴ）〉Ni2＋。[结论]Cd对日本青鳉是高毒物质,V和Ni是中毒物质,可见V与Cd和Ni一样应属于第1类污染物,建议参照Cd和Ni排放标准,将废水中V的排放浓度定为0.1～1.0 mg/L。     

1年生文冠果苗高生长规律

为了解文冠果苗的生长规律,提出从局部到整体的波形曲线模拟方法,用实际数据拟合参数,与Logistic,Richards以及二次多项式进行比较,探讨水分、施肥等经营措施对文冠果第1个生命活动周期各生长时段的影响。结果表明：基于波形曲线分析生命运动本质的做法是可行的：Logistic方程模拟1年生文冠果苗累计高生长的精度高于Richards方程;对于1年生文冠果苗的高生长,磷酸二铵底肥对其影响很小,氮肥能够增加高生长量,而土壤水分对其影响较大,较高含水量的土壤不利于苗木高生长。