杨圆蚧利它信息素和小蜂阻止产卵信息素对小蜂控制力的影响

寄主对寄生性天敌具有引诱作用和寄生小蜂分泌产卵信息素．是保证小蜂对寄主有较高的控制力的必要条件，研究发现杨圆蚧中存在着有利于长棒四节蚜小蜂和黄胸扑虱蚜小蜂寻找寄主和产卵的一类化学物质——利它信息素．主要存在于杨田蚧的介壳中．是一类具有水溶性特征的化台物．可帮助长棒四节蚜小蜂和黄胸扑虱蚜小蜂进行寄主的定位和辨识。因此可以保证在寄主低密度条件下．成功地进行寄主定位．对寄主进行有效的控制。长棒四节蚜小蜂和黄胸扑虱蚜小蜂在寄主杨圆蚧一龄固定若虫体上产卵后．留下可以阻止同种的其它个体或异种的个体进行寄主检查和产卵的物质．即产卵标速信息素。这样便极大地减少了杨田蚧之间复寄生现采的发生．确保了杨圆蚧若虫体内的小蜂有充足的营养．也使小蜂利用有限的卵．控制尽可能多的寄主．使杨圃蚧和小蜂保持在一定的种群水平。     

大瓶螺胚胎发育的初步观察

本文对大瓶螺（Ａｍｐｕｌｌａｒｉａｇｉｇａｓ）的胚胎发育进行了研究。由于大瓶螺卵具钙质卵壳，故采用定时取样，破壳取胚，间断观察的方法。在２５±１℃气温中，胚胎发育从卵产出母体后至孵化需２７４小时，长度增长２２倍。全过程可分为７个时期：卵裂期、囊胚期、原肠期、担轮幼虫期、面盘幼虫期、幼螺形成期和孵化期。对各期的外部形态特征进行了描述，并绘制了各期形态图，还对卵的结构，各期发育时间及胚胎大小变化作了描述。     

三倍体长牡蛎(Crassostrea gigas)不育性研究

三倍体长牡蛎(Crassostrea gigas)雌性怀卵量在0～2000万,雄性精量在0～1亿,大大低于正常二倍体。三倍体生殖腺发育受阻,大部分停留在增殖期和休止期,一部分虽发育至生长期和成熟期,但与同期的二倍体比较,生殖腺发育差。部分三倍体配子能完成受精作用,并发育至D形幼虫,但不能继续正常发育。卵子减数分裂后为含14～16条染色体的非整倍体。因此,三倍体长牡蛎是不育的。     

Short-term physiological response of the Pacific oyster, Crassostrea gigas, on exposure to varying levels of polycyclic aromatic hydrocarbon

In the present study, we investigate the short‐term adaptive physiological strategies to polycyclic aromatic hydrocarbon (PAH) of Pacific oysters, Crassostrea gigas, by exposing the oysters to varying levels of PAH (0, 50, 100 and 200 μg L⁻¹) for 7 days with a 3‐day acclimation period under laboratory conditions. The filtration rate (FR) and respiration rate (R) increased significantly at 50 μg L⁻¹ PAH and decreased at 100 and 200 μg L⁻¹ compared with the control. The absorption efficiency (Abs. eff.) was significantly impaired at 200 μg L⁻¹ PAH. Ammonia excretion (E) increased with increasing PAH levels, with a significant elevation at 200 μg L⁻¹. Although a significantly elevated FR was observed, oysters exposed to 50 μg L⁻¹ PAH showed scope for growth (SFG) similar to the control. This indicates that even at nominal levels, PAH contamination is a possible cause of reduced oyster production because of increased food demand. The oysters exposed to 200 μg L⁻¹ PAH showed negative SFG values, which could be a possible cause of growth stagnation or even mortality when the exposure is chronic.     

Reproduction, condition and mortality of the Pacific oyster Crassostrea gigas (Thunberg) in Sonora, México

Starting in 1997, mortality outbreaks in cultured oysters Crassostrea gigas have been reported in northwestern México. Previous studies have shown that massive die‐offs result from multi‐factor processes related to reproduction of the species. We studied the reproductive cycle and the condition index of cultured oysters in the coastal lagoon of El Soldado, Sonora, as well as the relationship of the life cycle with environmental parameters. We used oocyte diameter to determine reproductive stages and the condition index to describe the physiological state of oysters. Additionally, the temperature, salinity, seston and chlorophyll a were recorded at the study site. The results showed that C. gigas began accelerated reproductive activity in March under the influence of high temperature and increased concentrations of food. No spawning events were recorded and gametes were reabsorbed within the gonad in September and October. The results showed a period of nutrient storage during autumn–winter and another period of gamete production in spring–summer. A mortality event occurred at the end of winter, tied to significant increases in temperature and availability of food and in accelerated reproductive activity and high condition index. These conditions were very similar to those reported in other countries during summer die‐offs of C. gigas.     

cDNA cloning of Japanese oyster stress protein homologous to the mammalian 78-kDa glucose regulated protein and its induction by heatshock

ABSTRACT:    The 78-kDa glucose regulated protein (GRP78), a member of stress proteins, was cloned from a cDNA library of Japanese oyster Crassostrea gigas . The analysis on Japanese oyster GRP78 clone of approximately 2.6 kb revealed that the entire open reading frame was 1983 bp long and encoded 661 amino acid residues. At the DNA sequence level, the coding region of Japanese oyster GRP78 gene was 72, 62, and 62% identical to those of chicken GRP78, Japanese flounder HSP70, and Japanese flounder HSC71 genes, respectively. Deduced amino acid sequence of Japanese oyster GRP78 was 84, 62, and 62% identical to those of chicken GRP78, Japanese flounder HSP70, and Japanese flounder HSC71, respectively. Japanese oyster GRP78 contained an 18-residue sequence at the N-terminus that exhibits characteristics of a cleavable signal sequence. It also contained an ATPase domain, and a peptide-binding domain in addition to a Lys-Asp-Glu-Leu (KDEL) peptide motif that is involved in determining endoplasmic reticulum localization. Northern blot analysis showed that GRP78 mRNA was induced with heatshock treatment in the oyster tissues.     

El Niño–Southern Oscillation impacts on jumbo squid habitat: Implication for fisheries management

1. Dosidicus gigas is an ecologically and economically important squid species extensively distributed in the eastern Pacific Ocean. Its habitat is extremely sensitive to climatic and environmental variability.
2. The relationship between habitat pattern of D. gigas and El Niño–Southern Oscillation (ENSO, divided into the El Niño, ENSO-neutral, and La Niña events) was assessed from 1950 to 2015, using a habitat suitability index (HSI) modelling approach including two crucial environmental variables: sea surface temperature (SST) and sea surface height anomaly (SSHA).
3. On the basis of cross-correlation analysis, it showed that both SST anomaly and SSHA were significantly positively related to the ENSO index. Moreover, a significantly negative association was found between the HSI values and the ENSO index.
4. Due to the El Niño events, SST off Peru became higher and sea level rose, resulting in contracted areas of suitable SST and SSHA; consequently, suitable habitats for D. gigas dramatically decreased. In contrast, during the ENSO-neutral and La Niña years, the extent of suitable SST and SSHA increased due to the colder water and lower sea level, and suitable habitat for D. gigas expanded.
5. Moreover, the latitudinal gravity centre of HSI was significantly positively associated with the ENSO index. Relative to the ENSO-neutral and La Niña years, a southward movement of the monthly preferred SST isotherm for D. gigas during the El Niño years could explain the occurrence of more suitable habitats in southern waters off Peru.
6. These findings suggested that the ENSO event plays an important role in regulating environmental conditions off Peru and further affected the spatio-temporal distribution of D. gigas habitat.

     

长牡蛎壳金性状遗传参数评估及与生长性状的关联分析

采用家系选育与群体选育相结合的方法,以壳金性状和生长性状为主要选育指标,经过连续4代的选育获得了长牡蛎第4代壳金选育品系(F4)。本实验以F4代为亲本,采用巢式设计方法和人工授精技术,成功构建了25个长牡蛎壳金全同胞家系,分别测定了每个家系生长到9月龄时30个个体壳金性状颜色参数和生长性状,分析了2类性状的表型变异,并对壳金性状的遗传参数及与生长性状的相关性进行了分析。结果显示,壳金性状颜色参数L*、a*、b*、ΔE的遗传力分别为0.13±0.09、0.69±0.19、0.30±0.13、0.38±0.15;L*、a*、b*和ΔE之间的遗传相关和表型相关范围分别为–0.25~0.37、–0.1 9~0.8 0;颜色参数与各生长性状的遗传相关和表型相关均较低,分别为–0.04~0.26、–0.10~0.13。本研究表明长牡蛎壳金性状颜色参数的遗传力多为中高等水平,对其颜色继续进行选择改良,预期能达到良好的效果。此外,壳金性状与生长性状的相关性较低,不能利用二者之间的关系进行相互选择,只能将壳金性状和生长性状均作为目标性状进行协同选择,以实现同步改良2个性状的目的。     

长牡蛎出肉率与壳形性状的 QTL 定位分析

本研究以长牡蛎(Crassostrea gigas)F1全同胞家系为作图群体,在已构建的基于120个微卫星和66个SNP标记的长牡蛎性别平均连锁图谱上,利用PROC QTL 2.0软件对出肉率和壳形(壳宽和壳深)性状进行QTL定位分析。结果表明,共检测到13个相关的QTL,分布在3个连锁群上;其中,与出肉率相关的4个QTL定位在1号和3号连锁群上(LG1和LG3),表型解释率为0.25%~47.53%;与壳宽相关的3个QTL定位在10号连锁群上(LG10),表型解释率为0.71%~45.39%;与壳深相关的6个QTL也定位在LG10,表型解释率为3.37%~24.78%。根据QTL连锁群分析和性状相关性分析结果可以推测,出肉率与糖原含量性状以及壳宽与壳深性状分别具有相近的遗传特征,利用与相关性状共同关联的分子标记可以同时对出肉率与糖原含量性状、壳宽与壳深性状进行遗传改良。本研究结果为今后长牡蛎相关性状候选基因克隆和分子标记辅助育种提供了参考。     

秘鲁鱿鱼皮明胶-壳聚糖复合膜的性能与结构表征

为考察壳聚糖对鱿鱼皮明胶膜的改性效果,将壳聚糖添加到明胶溶液中,考察壳聚糖的添加量对鱿鱼皮明胶复合膜机械性能、水蒸气透过率、透光性及其结构的影响。结果表明,壳聚糖能有效改善鱿鱼皮明胶膜的有关性能指标,当鱿鱼皮明胶溶液与壳聚糖溶液以60∶40(v/v)比例混合,制得复合膜的断裂伸长率相比单一明胶膜下降,但其抗拉伸强度、透光率和水蒸气阻隔能力分别比单一明胶膜提高了652%、11%和48%;差示扫描量热仪、红外及扫描电镜分析结果显示,壳聚糖能与鱿鱼皮明胶相互作用,形成结构致密的均相体系,提高复合膜的热变性温度。综上可知,鱿鱼皮明胶与壳聚糖之间具有良好的相容性,壳聚糖是一种较理想的明胶膜改性材料。本试验结果为鱿鱼皮明胶作为食品保鲜膜的应用提了供依据。