孕激素暴露致食蚊鱼形态雄性化的生物学效应

目的：研究不同浓度孕酮（ PRO）暴露对雌性食蚊鱼（ Gambusia affinis）的形态雄性化生物学效应。方法将性未成熟的雌性食蚊鱼个体分别静水暴露于0.5、5、50和500 nmol/L不同浓度的PRO实验组中,并设置对照组和平行组。持续暴露42 d后观察与测定食蚊鱼的体长、体重、臀鳍第3鳍条和第14,15,16椎肋骨形态雄性化变化等指标,同时观察卵巢发育状况。结果食蚊鱼暴露42 d后,与对照组相比,50和500 nmol/L实验组食蚊鱼的体长（ BL）有极显著减少（分别P＜0.01）;无论是低浓度组还是高浓度组,暴露实验后体重（ BW）都有显著性或极显著下降（P＜0.05或P＜0.01）;PRO暴露对食蚊鱼身体健康指数（CF）的影响,只有在5 nmol/L浓度时差异有显著性（P＜0.05）;500 nmol/L浓度处理后,第3臀鳍条分节数（FJ）、长度（FL）和最宽处宽度（FW）差异有显著性（P＜0.05）,表明形态雄性化变化明显;其他浓度组则无明显区别（P＞0.05）;500 nmol/L PRO实验组中,雌性食蚊鱼的第14,15,16椎肋骨的L值、D值和L：D值都出现极显著性差异（分别P＜0.01）,表明形态雄性化变化明显;组织切片观察揭示,暴露组食蚊鱼卵巢中的卵母细胞发育受到不同程度的抑制,II、III时相卵母细胞胞核发生肿胀现象。结论孕激素暴露诱导雌性食蚊鱼形态雄性化的生物效应十分明显。     

放养食蚊鱼

放养食蚊鱼高书堂（湖北教育学院武汉４３００６０）刘灼见,邓青（武汉大学生命科学院４３００７２）从研究食蚊鱼的性腺发育及性周期规律中,认识到食蚊鱼不仅对环境治理、保障人体健康,而且作为中学、大学生物学实验材料都有着重要意义,因此,在全国较大范围内放养食...     

广东从化地区不同生境食蚊鱼种群的繁殖生物学特征

本文从繁殖群体的环境条件、形体特征、卵巢发育与繁殖力方面对广东从化地区溪流、池塘、农田3种不同生境的食蚊鱼(Gambusia affinis)种群展开比较研究。结果发现,无论流动水体溪流还是静水水体池塘和农田,食蚊鱼的繁殖期均在3~12月份,繁殖群体中雌鱼占比明显高于雄鱼(Chi-Square test,P0.01)。雌鱼周年平均体长及体重,池塘生境的显著大于农田和溪流生境。农田生境中雌鱼的个体怀卵量(24.1±12.1)粒,体重相对繁殖力(57.5±31.0)粒/g,二者均明显高于溪流生境[(16.6±11.6)粒,(40.8±15.5)粒/g]与池塘生境[(18.9±16.3)粒,(35.7±19.1)粒/g],但农田生境雌鱼成熟卵子的卵径显著小于溪流和池塘生境。结果表明,在环境稳定的池塘生境中,食蚊鱼的繁殖策略偏向k-对策特性;在人为干扰较大的农田生境中,食蚊鱼的繁殖策略偏向r-对策特性。不同类型生境中食蚊鱼的繁殖特性存在一定差异,主要与其栖息环境的稳定性和饵料生物的丰富度有关。     

乳白花黄耆(豆科)的一些新异名

通过对模式标本和模式产地标本以及大量腊叶标本的研究,结合野外居群生物学观察,认为科布尔黄耆(Astragalus koburensis Bunge)、宁夏黄耆(A.ningxiaensis Podlech et L.R.Xu)、河套盐生黄耆(Astragalus salsugineus Kar.et Kir.var.hetaoensis H.C.Fu)、德令哈黄耆(Astragalus acceptus Podlech et L.R.Xu)均为乳白花黄耆(Astragalus galactites Pall.)的异名,该文对其进行了订正。     

广州河涌污水暴露致食蚊鱼骨骼形态雄性化的影响

食蚊鱼(Gambusia affinis)骨骼发育具有性别二态性,雄鱼臀鳍与第14、15和16椎体脉棘的形态特化受雄激素所调控,因此可以作为生物标志物监测水环境中的雄激素污染。本文利用食蚊鱼臀鳍和椎体脉棘形态变化为指标,调查了生活在受城市废水严重污染的广州市河涌中的食蚊鱼受内分泌干扰物影响的现状。根据食蚊鱼生长情况和捕鱼的便利性,选择广州市海珠涌中下游宝岗大道段(BG)、洪德路段(HD)和黄埔涌中下游赤岗路段(CG)、苗艺路段(MY)4个采样点,同时设置不受城市废水污染的华南师范大学校区内的中心湖作对照点(REF)。测量了雌、雄食蚊鱼第4臀鳍条长度和第4与第6臀鳍条长度的比值,并采用食蚊鱼第14、15和16椎体脉棘的总长(L,μm)、投影长度(P,μm)、尾部尖端到脊柱的高度(D,μm),以及L︰D、P︰D和P︰L的比值来评价食蚊鱼骨骼形态变化。结果,与对照点相比,夏冬两季海珠涌和黄埔涌4个采样点成年雌性食蚊鱼的第4臀鳍条长度显著延长(P0.05或P0.01),第4与第6臀鳍条长度的比值明显增大(P0.05或P0.01),成年雌性食蚊鱼臀鳍显现形态雄性化的特征;尽管4个采样点成年雄性食蚊鱼第4臀鳍条长度均显著小于对照点(P0.01),但是所有采样点的成年雄性食蚊鱼第4与第6臀鳍条长度的比值则无明显差异(P0.05)。与对照点(REF)相比,夏冬两季海珠涌宝岗大道段(BG)、洪德路段(HD)和黄埔涌苗艺路段(MY)采样点成年雌性食蚊鱼第14、15、16椎体脉棘的投影长度(P)显著增加(P0.05或P0.01);海珠涌宝岗大道段(BG),黄埔涌赤岗路段(CG)和苗艺路段(MY)采样点成年雌性食蚊鱼的P︰D比值显著增加(P0.05或P0.01);海珠涌宝岗大道段(BG)和洪德路段(HD),黄埔涌苗艺路段(MY)采样点成年雌性食蚊鱼的P︰L比值也显著增加(P0.05或P0.01);成年雌性食蚊鱼的第14、15、16椎体脉棘出现了骨质增生,增长,并向前倾斜,显示不同程度的形态雄性化特征。可是,各采样点成年雄性食蚊鱼第14、15、16椎体脉棘的投影长度(P)、P︰D和P︰L比值则没有明显变化(P0.05)。结果表明,广州河涌水体中的环境内分泌干扰物对食蚊鱼产生明显的形态雄性化效应。     

库恩菇属一新组合种(国内新记录)

本文报导了A.H.Smith和L.R.Hesler1968年命名的Pholiota conica A.H.Smith et L.R.Hesler在我国的新记录, 并根据R.Singer1975年的分类系统进行了新组合Kuehneromyces conicus(A.H.Smith et L.R.Hesler)J.B.Wang et Z.B.Chen comb.nov.     

食蚊鱼（Gambusia spp.）入侵生态学研究进展

食蚊鱼(Gambusia spp.)是原产于北美洲的著名入侵物种,它对蚊类幼虫具有很强的捕食压力,被作为疟疾防治生物工具而在全世界温带和热带地区扩散.近20多年来的研究认为,食蚊鱼通过食物竞争和捕食等机制威胁引入地的无脊椎动物、鱼类、两栖类的生存,显著影响引入地的生物多样性.它们具有广泛的生境适应性、生长迅速、卵胎生、高生殖率、对生殖生态条件无特殊要求等特点.另外,它们的个体野外寿命不超过2a,种群更新速度快,种群内形成春季和夏季两个繁殖群体,并具有不同的繁殖生物学特点,因而形成复杂的世代结构.遗传上,雌鱼具有混交及能长期贮存精子的特点,能快速建立种群并克服奠基效应.这些种群通过快速适应性进化而形成一定规模的地理群体.当前,由于食蚊鱼在预防疟疾的工作中仍具有不可替代的作用,它会借助于人力的作用而继续扩散.为减轻它对非目标地区和非目标生物的影响,应进一步深入开展其入侵生态学研究.     

四川都江堰东方草鸮的繁殖记录

<正>东方草鸮(Tyto longimembris)隶属于鸮形目草鸮科,共有6个亚种的分化,我国分布的2个亚种为T.l.chinensis和T.l.pithecops。东方草鸮在我国主要分布于西南和华南(chinensis)以及台湾(pithecops),国外分布于印度次大陆、东南亚、菲律宾、新几内亚岛和澳大利亚(del Hoyo et al.1999,郑光美2011)。在《中国鸟类分类与分布名录》(第二版)中,东方草鸮的分布区并不包括四川省。实际上,早在2000年时就曾有报道称在四川省南充市高坪区发现草鸮的分布(胡锦矗2000),一直未能引起关注。有关东方草鸮繁殖生物学的资料,大多来自国外的     

广州地区人工湖食蚊鱼的种群特征

为调查广州地区人工湖泊食蚊鱼的分布以及探究不同生境要素下食蚊鱼的生长繁殖特点和种群特征,于2012 年5 月-7月份对广州地区6 区19 个人工湖进行实地考察,发现所考察的人工湖均有食蚊鱼的分布。利用捕捞量比较其中4 个人工湖食蚊鱼种群数量,结果显示水体相对富营养化的月湖食蚊鱼数量比其余3 个人工湖高出39.5-43.1 倍。比较4 个人工湖食蚊鱼的形态、摄食、相对怀卵量以及种群结构等指标,结果显示月湖食蚊鱼肥满指数显著低于其余3 个人工湖,而肝体指数和消化道饱满指数却显著高于其余3 个人工湖。同时,月湖雌鱼的相对怀卵量也显著高于其余3 个人工湖,其种群中幼鱼所占比例最大,成鱼中雄鱼所占比例大于雌鱼。反映了水体饵料生物丰富条件下,更有利于食蚊鱼的摄食和繁殖,种群结构低龄化,呈快速增长型。     

卵胎生入侵种食蚊鱼的两性异形和雌性繁殖输出

检测了卵胎生入侵种食蚊鱼(Gambusia affinis)繁殖期个体大小和形态特征的两性异形以及雌性繁殖输出。结果表明,繁殖期,雌性个体的数量显著大于雄性个体,雌性个体的体长显著大于雄性个体,食蚊鱼属于偏向雌性的两性异形。以体长为协变量的One-way ANCOVA及后续的Tukey's检验显示,特定体长食蚊鱼的雌性个体的头宽、眼间距、体宽和体重均显著大于雄性个体;头长和尾鳍长的两性间差异不显著。6个形态特征变量的主成分分析(Eigenvalue≥1)发现,前2个主成分共解释65.1%的变异。头宽、眼间距、体宽和体重在第一主成分有较高的正负载系数(解释45.4%变异),头长在第二主成分有较高的负负载系数(解释19.7%变异)。食蚊鱼的繁殖输出与母体个体大小的线性回归显示,窝仔数和窝仔重均与母体体长、体重呈显著的正相关;食蚊鱼的繁殖输出与母体局部特征的线性回归显示,窝仔数和窝仔重均与母体头宽、眼间距和体宽呈显著的正相关。窝仔数与后代个体的平均体长呈显著的正相关、与后代个体的平均体重相关不显著,后代个体大小与数量不发生权衡。食蚊鱼繁殖期的性别比例、个体大小和局部形态特征的两性异形受生育力选择、性选择、生态位分化、食物竞争等多种选择压力的作用,也有利于该物种种群扩张和快速入侵。     

Effects of broad band electromagnetic fields on HSP70 expression and ischemia-reperfusion in rat hearts

Although exposure to broad band (0.2-20 MHz) electromagnetic fields (EMF) is part of the treatment of several diseases, little is known as to their effects on myocardial protein expression and resistance to ischemia-reperfusion (I/R). We exposed Sprague-Dawley rats to either high (H, 10 min/day at 200 V/m, 36.1 microT) or low (L, 2 min/day at 30 V/m, 11.4 microT) intensity broad band EMF for 15 days. At the end of the treatment, myocardial HSP70 was 32 +/- 8% (mean +/- SEM) higher in L (P = 0.01) than in control (C), whereas in H it remained the same as in C. Electron microscopy revealed sporadic ruptures of mitochondrial cristae in H hearts, with no differences in other parameters. Malondialdehyde was increased in treated hearts (P < 0.05), but especially in H (P = 0.008). To assess the protective role of HSP70 during I/R, hearts were Langendorff-perfused with Krebs-Henseleit. After I/R, C hearts displayed depressed rate. pressure (-13 +/- 7%) and increased end-diastolic (+9.2 +/- 2.8 mmHg) and perfusion pressures (+30 +/- 10 mmHg). In H and L, rate. pressure recovery was similar to C (-2 +/- 21% and -12 +/- 16%, respectively, P = NS). In contrast, both end-diastolic and perfusion pressures were higher in L than in H (30.8 +/- 5.4 vs 18.2 +/- 3.5, P = 0.01, and 54 +/- 8 vs 21 +/- 8 mmHg, P = 0.01, respectively) indicating diastolic derangement in L. In conclusion, the effects of broad band EMF on HSP70 appear to be biphasic, and HSP70 overexpression might not be directly related to improved protection against I/R.     

Effect of substrate concentration on dry mesophilic anaerobic digestion of organic fraction of municipal solid waste (OFMSW)

The influence of total solid contents during anaerobic mesophilic treatment of the organic fraction of municipal solid waste (MSW) has been studied in this work. The work was performed in batch reactors of 1.7L capacity, during a period of 85-95 days. Two different organic substrate concentrations were studied: 931.1 mgDOC/L (20% TS) and 1423.4 mgDOC/L (30% TS). Experimental results showed that the reactor with 20% total solids content had significantly higher performance. Thus, the startup phase ended at 14 days and the total DOC removal was 67.53%. The startup in reactor R30 ended at 28 days obtaining 49.18% DOC removal. Also, the initial substrate concentration contributed substantially to the amount of methane in the biogas. Hence, the total methane production in the methanogenic phase was 7.01 L and 5.53 L at the end of the experiments for R20 and R30, respectively.     

The effect of various Aeromonas bestiarum vaccines on non-specific immune parameters and protection of carp (Cyprinus carpio L.)

Aeromonas bestiarum is one of the causal agents of motile aeromonad infection/motile aeromonad septicemia (MAI/MAS) in fish. Infections of the bacterium is an increasing problem in commercial carp (Cyprinus carpio L.) farmed in Poland. Non-specific immune response of the fish, vaccinated with oil-emulsified experimental vaccines containing formalin killed whole cells (WCs), formalin killed whole culture (WCt) or crude LPS (50 or 1250 microg per fish) were studied on days 7 and 30 after vaccination. Fish vaccinated for 30 days were challenged with the pathogen and mortalities recorded over 14 days. The cumulative mortalities were 10%, 0%, 20% and 20% in WCs, WCt, LPS-1250 and LPS-50 groups, respectively, whereas 70% fish died in the control group. Vaccinated fish showed significant increase of phagocytic activity (PA) and phagocytic index (PI). The total serum Ig (TSIg) level was significantly higher in most vaccinated fish groups than in control. Moreover, WCs and WCt induced significant increase of mucus lysozyme level in vaccinated fish.     

Brood mixing and reduced polyandry in a maternally mouthbrooding cichlid with elevated among-breeder relatedness

Uniparental maternal brood care often coincides with multiple paternity and single maternity of broods, possibly reflecting benefits of polyandry and costs of uniparental care. Genetic data from the maternally mouthbrooding cichlid fish Simochromis pleurospilus revealed the opposite pattern--low polyandry and allomaternal care. More than 70% of the investigated females had mated with a single male, and 14% of the females had unrelated fry in their broods. Broods with foreign fry were in the late stage of brood care, in which females guard free-swimming fry and recall the broods into their mouths for protection. With one exception, fostering females were related to their adopted fry at the level of first cousins (R(QG) > 0.12), but relatedness between fosters and adopted fry was not significantly higher than between fosters and fry tended by other females. Relatedness among breeders extended to the level of first-order relatives. Mean relatedness among contemporaneously breeding dams (R(QG) = 0.08) was significantly higher than among dams breeding in different seasons (R(QG) = -0.04), which suggests a temporal or spatial concentration of mouthbrooding relatives. Indeed, females sometimes brood in small groups. This behaviour may reduce brood predation but will increase the risk of brood mixing, which is possibly mitigated by low costs of brood care and indirect benefits accrued by relatedness among the breeders in the group. Remarkably, the apparent inbreeding potential did not give rise to bet-hedging polyandry or active avoidance of relatives, as half of the mated individuals were related at R(QG) > 0.13 and polyandry did not coincide with high within-pair relatedness.     

Temperature effects on immune response and hematological parameters of channel catfish Ictalurus punctatus vaccinated with live theronts of Ichthyophthirius multifiliis

This study evaluated the influence of temperature on the immune responses and hematological parameters in channel catfish Ictalurus punctatus immunized via intraperitoneal injection with live theronts of Ichthyophthirius multifiliis. Fish were distributed in 18 aquaria and received 9 treatments: 4 groups of fish were vaccinated with live theronts and maintained at constant temperature 15 °C, 20 °C, 25 °C and 30 °C; 3 groups of fish vaccinated and subjected to cycling temperature regime from 15-25 °C, 20-25 °C and 20-30 °C, changed 5 °C each day; 2 groups of fish were not vaccinated and served as controls at 25 °C, one with Ich challenge and the other without challenge. Non vaccinated fish and those vaccinated at 15 °C or 15-25 °C did not show anti-Ich antibodies in the serum 14 and 21 days post-immunization. The antibody levels were significantly higher from fish vaccinated at 25 °C, 30 °C, 20-25 °C and 20-30 °C compared to fish at 15 °C, 20 °C and 15-25 °C both 14 and 21 days post-immunization. At constant water temperature, fish vaccinated at 15 °C showed significantly higher mortality rate (67.8%, P < 0.05) than those vaccinated at 20 °C, 25 °C, and 30 °C (0-10.7% mortalities). At cycling water temperature, fish vaccinated at 15-25 °C showed significantly higher mortality rate (67.8%) than those vaccinated at 20-25 °C and 20-30 °C (P < 0.05). Twenty days after immunization fish vaccinated at 30 °C and 20-30 °C showed significant increase in the red blood cells, white blood cells, thrombocytes and monocytes. Six days after challenge with I. multifiliis theronts the fish showed decreased white blood cells, thrombocytes and monocytes. This study suggests that vaccinated catfish were severely impacted by low temperature, either at 15 °C constant temperature or at 15-25 °C cycling temperature. The fish showed no anti-Ich antibodies and suffered high mortality similar to non vaccinated control fish.     

Life history of hawthorn spider mite Amphitetranychus viennensis (Acarina: Tetranychidae) on various apple cultivars and at different temperatures

Development duration and reproduction rate of hawthorn spider mite Amphitetranychus viennensis (Zacher) were carried out on five different apple cultivars (Amasya (local cultivar), Golden Delicious, Granny Smith, Starking Delicious and Starkrimson Delicious) at 25 degrees C, 65 +/- 10% RH and 16:8 L:D. In addition, the same parameters were determined on Golden Delicious leaves at three constant temperatures (20, 30 and 35 degrees C, 65 +/- 10% RH and 16:8 L:D) in the laboratory. A. viennensis showed a better performance on Golden Delicious than on the other apple cultivars. This was mainly due to a short development time (10.7 days), high daily egg production (5.2 eggs/female/day) and early reproduction peak. The highest intrinsic rate of natural increase (rm) was determined on the variety Golden Delicious (rm = 0.247/day), while the lowest one was observed on the variety Starking Delicious (rm = 0.215/day). The developmental periods of A. viennensis varied from 7.4 to 18.8 days at 35 and 20 degrees C for females, while it varied from 7.9 to 17.2 days at 30 and 20 degrees C for males. The development threshold of the eggs and pre-adult stages were 9.72 and 9.07 degrees C, total effective temperature was 72.99 and 185.18 degree-days, respectively. The mean generation time (To) of the population ranged from 16.13 days at 30 degrees C to 29.15 days at 20 degrees C. The net reproductive rate (R0) increased from 54.33 female/female at 20 degrees C to 78.34 female/female at 25 degrees C, and decreased to 75.71 female/female at 30 degrees C. The highest intrinsic rate of increase (rm) was reached at 30 C (rm = 0.268/day), the lowest one at 20 degrees C (rm = 0.136/day).     

T-maze behaviour in broiler chicks is not sensitive to right-left preferences, test order or time-of-day

There is substantial individual variation in the time taken by broiler chicks to traverse a T-maze and thereby reinstate visual contact with their companions. Chicks completing this task quickly (high performance, HP) subsequently grew faster in the laboratory and on farm, exhibited greater sociality, and showed less pronounced adrenocortical responses to a partial water immersion stressor than did their slower (low performance, LP) counterparts [Marin, R.H., Jones, R.B., 1999. Latency to traverse a T-maze at 2 days of age and later adrenocortical responses to an acute stressor in domestic chicks. Physiol. Behav. 66, 809-813.; Marin, R.H., Arce, A., Martijena, I.D., 1997. T-maze performance and body weight relationship in broiler chicks. Appl. Anim. Behav. Sci. 54, 197-205.; Jones, R.B., Marín, R.H., García, D.A., Arce, A., 1999. T-maze behaviour in domestic chicks: a search for underlying variables. Anim. Behav. 58, 211-217.]. Given its simplicity, rapidity and non-invasiveness, the T-maze test might represent a commercially attractive selection criterion for future breeding programmes if this behavioural trait exhibits sufficient genetic variability. However, it is first necessary to ensure that performance in the T-maze is not sensitive to potentially confounding variables, such as existing preferences to turn right or left at the junction of the maze, the order of testing, or the time of day. In the present study, 240 newly hatched, mixed-sex broiler chicks (Cobb) were randomly allocated to 12 groups of 20 upon receipt. When they were 2 days of age a group of 20 chicks was placed in the brood area of each of two T-mazes at 0830 h; the brood areas were positioned on either the right or the left sides of the mazes. After acclimatisation, one chick from each group was placed in the isolation chamber of the T-maze and we recorded the time it took to traverse the maze. This procedure was repeated until all 20 chicks and all 12 groups had been tested. The locations of the brood areas were rotated after each block of 20 tests. Testing was completed in the same day and two groups were tested at each of the following times: 0900, 1030, 1200, 1330. 1500, and 1630 h. Analyses of variance (ANOVA) revealed no detectable effects of: positioning the brood area on the right or the left side of the T-maze (F(1,200)=0.06, P<0.80), test order (F(19,200)=0.48; P<0.96), or time-of-day (F(5,234)=0.44; P<0.81). These findings strongly suggest that the future classification and possible selection of broiler chicks according to their T-maze responses are unlikely to be confounded by right-left preferences, test order, or the time of day.     

Reproductive cycle in female Waigieu seaperch (Psammoperca waigiensis) reared under different salinity levels and the effects of dopamine antagonist on steroid hormone levels

Waigieu seaperch (Psammoperca waigiensis) is a tropical marine finfish species, which may inhabit wide range of salinity during the entire life cycle. Regardless of the wide salinity tolerance, little is known about how salinity may influence the reproductive endocrinology of this important tropical species. In the present study, we investigated the seasonal variations in steroid hormone levels, oocyte maturation (OM) and ovulation in fish reared under different salinity levels. In addition, we investigated the effects a dopamine antagonist (domperidone: DOM) during the peak spawning period. Mature brood fish at 3 years old were cultured in four different salinities of 5, 10, 20 and 30‰ (part per thousand, ppt) from March to December 2007. Blood samples were collected monthly and key steroid hormones (testosterone (T), 11-ketotestosterone (11-KT), 17β-estradiol (E2) and progesterone (P)) levels in female fish plasma were analyzed using enzyme immunoassay method. OM, ovulation and several reproductive performance indexes were evaluated twice per month during the breeding season. Plasma hormone analysis showed significant differences in fish groups cultured in different salinities during the seasonal cycle. The gonadosomatic index (GSI) gradually increased from March, peaking in July at 10 and 30‰, and then decreased thereafter until December. Plasma steroid levels (E2, T, 11-KT and P) were observed in variable concentrations during the spawning period and showed monthly fluctuations that were apparently salinity dependent during on and off-seasons. Interestingly, 11-KT levels were found in small amounts in female fish and peaked in September at salinities of 10 and 20‰. DOM exposure produced significant differences in steroid hormone levels that were apparently dependent on dose, exposure time and the individual hormone. The present study indicated that holding Waigieu seaperch brood fish in different salinities during the breeding season produced significant effects on gonadal development and spawning incidences. The first spawning was observed on 8th of April for all groups after 100% water exchange at night. No significant differences of absolute and relative fecundity were observed between groups. Fish held at 10 ppt salinity during the breeding season spawned naturally, but maturity and spawning rates were reduced and no hatching was observed at the same salinity. Fish holding at 5‰ resulted to 100% mortality in brood fish. This indicated that salinity limits for oocyte maturation or ovulation and subsequent reduction in spawning, but embryonic development requires a higher salinity. The effect of salinity on embryo development and hatching rate suggests that in breeding season the brood fish spawned in areas where the salinity and other parameters are favorable.     

Stability of interleukin 6, soluble interleukin 6 receptor,interleukin 10 and CC16 in human serum

The stability of interleukin 6 (IL-6), its soluble receptor (sIL-6R), IL-10 and CC16 or uteroglobin (an endogenous cytokine inhibitor) in human serum was examined using an accelerated stability testing protocol according to the Arrhenius equation. Further, the effect of time delay between blood sampling and sample processing, clotting temperature and repeated freeze-thaw cycles on serum levels of these proteins were determined. Paired serum samples were stored at 4 degrees C, 20 degrees C, 30 degrees C and 40 degrees C for 1 to 21 days. We found that IL-6 and CC16 concentrations did not change at 4 degrees C, 20 degrees C and 30 degrees C. Interleukin-6 concentrations significantly declined after 11 days at 40 degrees C. The concentrations of sIL-6R and IL-10 did not change at 4 degrees C but significantly decreased at 20 degrees C (after 21 and 14 days respectively), 30 degrees C and 40 degrees C (after 1 day at both temperatures for both cytokines). Arrhenius-plots indicated that sIL-6R and IL-10 are stable for at least several years at -20 degrees C and -70 degrees C, respectively. Since their relative stability, no Arrhenius-plot could be calculated for IL-6 and CC16. The concentrations of the proteins examined were not significantly altered by repeated freeze-thaw cycles, nor by extended clotting times at 4 degrees C or 20 degrees C. We conclude that serum samples for the determination of IL-6, sIL-6R and CC16 can be stored at -20 degrees C for several years, but for IL-10 determinations, storage at -70 degrees C is recommended.