Temperature and food‐level effects on reproductive investment and egg mass in vendace,Coregonus albula

Abstract Individual variation in reproductive investment is important for recruitment and population dynamics in fish populations. Thus, it is crucial to understand how these decisions are influenced by environmental conditions. Here, the influence of growth variation during gonadogenesis or early life on reproductive investment in vendace, Coregonus albula (L.) was investigated. A set of cohorts of mature females were sampled over two different years with contrasting climate conditions and food levels, using total length at age 1 year as a proxy for juvenile growth. Relative reproductive investment and individual egg mass were lower in the favourable year (elevated temperatures and zooplankton densities) when the females were in better condition compared with a less favourable year (lower temperatures and zooplankton densities). Female vendace demonstrated plasticity in their allocation to relative reproductive investment and egg mass, probably induced by diverging environmental conditions. This phenotypic response to growth may have strong effects on recruitment and population growth rate.     

Changes in ovary and testis and breeding fitness of the climbing perch,Anabas testudineus (Bloch, 1792), exposed to sub‐lethal concentrations of monocrotophos

Monocrotophos (MCP) is one of the organophosphate pesticides extensively used in agriculture and animal husbandry. The present study reports the effects of sub‐lethal concentrations of MCP on gonadosomatic index (GSI), gonadal histology and breeding fitness of the fish Anabas testudineus. The fish were exposed to three sub‐lethal concentrations of monocrotophos (T1: 3.5 mg/L, T2: 5.3 mg/L and T3: 10.6 mg/L) for 45 days with 12 fish (males and females in equal numbers) in each tank, and one group was kept as control (C) without any treatment. GSI decreased in all treatment groups in comparison with control. Significant decrease in fertilization and hatching rate was observed at all concentrations in comparison with control on 15, 30 and 45 days of monocrotophos exposure. The decreased vitellogenesis, disruption of follicular wall and oocyte atresia were observed in all the treated females at 30 and 45 days of exposure. Rupture of seminiferous tubules was noticed in all the treated males irrespective of exposure periods. The results thus indicated that monocrotophos could deleteriously impact the gonadal structure and function in A. testudineus, which could seriously impact the reproductive success of the animal.     

Estimation of the spawning grounds of chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis> and spotted mackerel <Emphasis Type="Italic">Scomber australasicus</Emphasis> in the East China Sea based on catch statistics and biometric data

The spawning grounds of the chub mackerel (Scomber japonicus) and spotted mackerel (Scomber australasicus) in the East China Sea were estimated based on catch statistics of the Japanese large- and medium-type purse seine fishery from 1992 to 2006. Biometric data were obtained from specimens caught by purse seiners in the East China Sea from 1998 to 2006. Gonadosomatic index (GSI) at 50% sexual maturity of chub mackerel and spotted mackerel females was 2.5 and 2.6, respectively. Using this criterion for GSI, chub mackerel larger than 275 mm and spotted mackerel larger than 310 mm in fork length were considered to be mature. Mature chub mackerel was observed in the area of 15–22°C sea surface temperature (SST), and mature spotted mackerel was observed in the area of 17–25°C SST. The spawning period of chub mackerel ranged from February to June, and that of spotted mackerel ranged from February to May in the East China Sea. The spawning grounds were estimated from the distributions of catch per unit effort (CPUE) of spawners and SST. As a result, the spawning ground of chub mackerel was estimated to be in the central and southern part of the East China Sea and the area west of Kyushu in February, March, and April, and in the central part of the East China Sea, the area west of Kyushu and Tsushima Straight in May, and in Tsushima Straight and western part of the Sea of Japan in June. The spawning ground of spotted mackerel was estimated to be in the central and southern part of the East China Sea and southern coastal area of Kyushu in February, March, and April, and the central and southern part of the East China Sea and the area west of Kyushu in May.     

Assessing sexual maturity of feminized Japanese eel Anguilla japonica by measuring eye size

For efficient production of Japanese eel Anguilla japonica eggs, knowledge of the status of the sexual maturity of potential broodstock females is important because this status directly influences the time required to produce mature eggs by successive hormone doses. Here we apply an eye index (relative eye size) to evaluate the gonadal status of feminized A. japonica, which were induced by administration of estradiol-17β. Examination of gonad somatic and eye indexes of 267 feminized eels, cultivated for 12–56 months, revealed a significant correlation between these two indexes. Artificial maturation of 35 feminized eels showed that the number of hormone injections administered before ovulation was significantly lower as the eye index score increased, indicating availability of this noninvasive method of predicting sexual maturity of feminized eel. There was no correlation between eye index and fertilization rate, hatching rate, or larval survival rate, suggesting that sexual maturity before hormonal treatment does not affect egg quality.     

雪花梨S16-RNase基因全长cDNA克隆及序列分析（英文）

    通过逆转录PCR(RT-PCR及快速扩增cDNA末端(RACE)技术从中国白梨品种'雪花'梨中克隆到S16-RNase基因的全长cDNA序列(GenBank接受号为DQ991388)该cDNA克隆总长1101 bp,包含1个完整的开放阅读框,编码228个氨基酸S16-RNase表现出梨S-RNase基因的基本结构特征,即其具有5个保守区(C1,C2,C3,RC4及C5)和1个高变区在推导氨基酸水平上,S16-RNase与梨其他S-RNase基因的相似性为63%至74%,但与苹果S9-RNase的相似性高达95%通过多序列比对构建进化树,分析梨S16-RNase与蔷薇科植物其他S-RNase基因的遗传进化关系结果表明,S16-RNase与苹果亚科S-RNase基因形成一个亚科特异而非种特异的S-RNase基因类群;且不同S-RNase基因间存在属内种间遗传距离远于属间种问遗传距离现象     

Evidence of density-dependent effects on population variation of Japanese sardine (Sardinops melanosticta) off Korea

Interannual variation of some biological parameters for the Japanese sardine, Sardinops melanosticta, population in Korean waters was investigated using scientific surveys and fisheries information since the late 1970s. The abundance and geographical coverage of sardine eggs were high (peak in 1986) and broad when spawning biomasses were high in the mid 1980s, and vice versa in the late 1970s and the early 1990s. Also, feeding and spawning areas based on fisheries information exhibited the same pattern of expansion/contraction as seen in ichthyoplankton surveys. Annual Gonadal Somatic Index (GSI) in spawning season (February to April) and the size at age 1 of sardine were reduced during the high abundance period. It is suggested that density‐dependent effects on the reproduction and growth of the sardine population in Korean waters existed.     

苜蓿自交不亲和性研究

实验中探讨了苜蓿自交不亲和性和遗传特征。结果得出:1.苜蓿自交结荚百分率为0～92％,平均为27.6％。苜蓿自交不亲和性在群体中呈连续、偏态分布。2.苜蓿自交不亲和性反应主要发生在雌蕊组织下部(子房及子房腔)。3.确定自交不亲和或自交亲和性的判别函数方程为Y=-0.0804x_1—0.5228x_2+0.6117_3。4.苜蓿自交不亲和性受单位点、复等位基因控制,并具有CSI遗传特点。5.S基因与过氧化物同工酶基因(Prxl)为连锁,两者间重组值为27％。6.PSC的遗传力h~2=62％,选择无论对亲和性和不亲和性均为有效。根据本试验结果讨论了苜蓿SI的测度指标、授粉方式及不亲和性的数量差异问题,并探讨了紫花苜蓿与黄花苜蓿种的分类差异,认为两者理应属同一种或种内不同生态型。     

黄海北部日本鲭繁殖生物学特征的年代际变化

根据1986年和2010年在黄海北部取样测定的日本鲭(Scomber japonicus)产卵群体基础生物学数据以及怀卵量计数结果, 对其繁殖生物学特征的年代际变化进行了研究。结果表明, 在日本鲭产卵群体基础生物学特征方面, 1986年的叉长、体质量、纯体质量和性腺重这4项基本生物学指标的范围和平均值均明显大于2010年, 年龄结构从1986年由1⁺~7⁺龄组成, 2⁺龄和3⁺龄为优势组, 改变为2010年由1⁺~3⁺龄组成, 2⁺龄为优势组。在性腺成熟度组成和性腺指数(GSI)方面, 2次采样均发现日本鲭雌鱼性腺成熟度以Ⅳ期和Ⅴ期为主; 开始排卵前, GSI随性腺成熟度的增加而增加; 相同叉长组而言, 2010年平均GSI较1986年呈现增加趋势。相同叉长组的繁殖力分析表明, 相对于1986年, 2010年体质量相对繁殖力升高了11.93%, 而绝对繁殖力则下降了18.45%。这些繁殖生物学特征的变化可能是由于日本鲭群体年龄结构简单化、个体小型化、生长速度加快等原因造成的。为了今后更好地保护并可持续利用日本鲭资源, 在现有的围网休渔制度的基础上, 建议在东黄海日本鲭各主要产卵场及其产卵期制定其他相应的保护措施, 以限制其他捕捞网具对该物种产卵群体的过度捕捞。

     

北太平洋长鳍金枪鱼卵巢的发育特征

根据2013年10月–2014年2月在北太平洋海域(29°08′~41°08′N,163°50′~144°19′W)采集的364尾长鳍金枪鱼的卵巢样本,利用组织学分析,详细描述了长鳍金枪鱼卵巢、卵细胞的发育阶段。结果显示,北太平洋长鳍金枪鱼卵巢内同时存在不同时相的卵细胞,为分批产卵类型;组织学上,长鳍金枪鱼的卵细胞发育过程分为6个时相,卵巢发育过程分为6个时期;卵巢成熟指数在成熟期为Ⅰ~Ⅴ期时逐渐增大,在Ⅵ期时减小;北太平洋长鳍金枪鱼产卵高峰为12月中旬和1月初,其卵巢成熟指数随纬度的升高呈递减趋势,随经度变化规律不明显。研究表明,通过对北太平洋长鳍金枪鱼卵巢的发育特征的分析与探讨,可为北太平洋长鳍金枪鱼的资源状况评估及渔业可持续发展提供生物学信息。     

红笛鲷（Lutjanus sanguineus）性腺发育初步研究

用组织学方法对1．5～2．5龄红笛鲷的性腺发育进行研究。结果表明：雌性红笛鲷GSI在3—5月处于较高水平,5月达到最高值（0．14％）,6-7月呈下降趋势,8月略有回升,而后一直处于较低水平;雄性红笛鲷GSI的周年变化趋势与雌性红笛鲷基本相似;雌雄红笛鲷HIS的周年变化趋势基本一致,即3月最高（雄性红笛鲷为1．73％,雌性红笛鲷为1．71％）;雌性红笛鲷除6-8月外,其GSI与HSI均呈负相关,而雄性红笛鲷在5～12月GSI与HSI呈正相关,其他月份呈负相关。另外还发现精巢中精原细胞与卵巢第Ⅱ、Ⅲ时相细胞的出现几率与雌雄红笛鲷的GSI周年变化一致。精巢的发育经历了精原细胞、初级精母细胞、次级精母细胞、精子细胞、精子整个发育过程,但结合解剖学特征总体判断,精巢仅发育到Ⅳ期早期;在雌鱼只观察到卵原细胞、第Ⅱ时相卵母细胞、第Ⅲ时相卵母细胞,结合解剖学特征判断卵巢只发育到Ⅱ期。