家蚕隐性灰色卵（gr—r）基因作用与卵壳构造

用扫描电镜观察比较了隐性灰色卵（ｇｒ－ｒ）和正常型卵的卵壳表面及断面构造，探讨了ｇｒ－ｒ基因对卵壳形成的影响。结果表明，隐性灰我以卵的卵壳表面构造与正常型卵相似，但其断面中层构造与正常卵迥异。正常为平行排列多层状结构，而ｇｒ－ｒ则可分为内，外两个亚层，外亚层与正常卵相似，内亚屋为混乱无序状结构，这表明ｇｒ－ｒ基因对巢滤泡形状的影响较小，对分泌机能的影响较大。ｇｒ－ｒ基因作用的强度远不如其他灰色...     

Early assessment of gilthead sea bream (Sparus aurata) spawning dynamics by mini‐broodstocks

The implementation of any sustainable breeding program requires a maximization of effective size (Ne) to maintain inbreeding rate at minimum levels. However, the control of Ne remains a major challenge for those species whose reproduction in captivity is based on a spawning strategy where there is no control over the established matings. The present study aims to assess the spawning dynamic of gilthead sea bream (Sparus aurata) at different dates from two mini‐broodstocks (4 ♀ and 4 ♂). Here we report the use of a simple protocol based on the genotyping of fertilized eggs from a reduced set of microsatellite loci which provides a quick evaluation of daily spawning in terms of family structuring (number of active breeders and number and family size). According to our results, the daily spawning dynamics is characterized by a fluctuation in the number of active breeders, reaching maximum values (until 100%) during peak production phase. However, the proportion of possible mating (families) in a single daily spawning never exceeded more than 81%. Unbalanced parental contributions were highly frequent, with extreme cases involving the assignment of 50%–90% of the offspring to a single family. Therefore, the use of mini‐broodstocks and the grouping of spawning harvested at different dates are proposed as strategies to minimize the inbreeding risk by providing a more optimal pattern of family structuring (increase in the number of families obtained and a more balanced parental contributions) that entails a more conservative Ne/N ratio.     

Colonizing Islands of water on dry land—on the passive dispersal of fish eggs by birds

The vast majority of global freshwater ecosystems are small lakes with less than 100 m² surface area. These lakes are often unconnected to other water bodies but frequently host fish populations. Existing explanations for how fish colonize such remote habitats often involve birds as vectors transporting fish eggs as propagules. In this study, we aim to quantify the prevalence of these explanations among relevant societal groups as well as their scientific knowledge basis. We analyzed entries in online blogs and forums and surveyed the opinions of local stakeholders and decision makers using a questionnaire. To collect published scientific knowledge, we conducted a structured literature review. Our results reveal a discrepancy between commonly found beliefs and the empirical knowledge supporting those beliefs: Dispersal of fish eggs by water birds was overall the most frequent explanation online and in the questionnaire. In the scientific literature, however, we found hardly any empirical research on passive fish egg dispersal. We propose research directions for how to close this gap of knowledge and suggest that future empirical studies on passive fish egg dispersal may be inspired by existing work on passive dispersal in aquatic invertebrates. Mitigating the belief‐evidence discrepancy on fish dispersal will be essential to better understand the patterns of fish biodiversity across landscapes, to counteract its losses, and inform management strategies for invasive fish species.     

基于DNA条形码技术对江门沿岸海域夏季鱼卵的鉴定

以江门沿岸海域夏季采集到的鱼卵研究对象,利用DNA条形码技术分析鉴定鱼卵种类。本研究获得鱼卵个体有效线粒体COI序列信息217个,测序成功率为68.5%。经BOLD数据库比对分析,成功鉴定鱼卵5目14科19属20种(未知种2种);种内遗传距离为0~0.006,平均遗传距离为0.002,种间遗传距离为0.149~0.325,平均遗传距离为0.255,种间遗传距离为种内遗传的128倍;鱼卵样品以鲈形目数量最多,占51.8%;鲱形目次之,占24.8%;其中鱼卵优势种为黄斑鲾(Photopectoralis bindus)、日本鳀(Engraulis japonicus)、大甲鲹(Megalaspis cordyla)、粗鳞鮻(Chelon subviridis)、金钱鱼(Scatophagus argus)、龙头鱼(Harpadon nehereus)、亚洲(Sillago asiatica)。本次调查川山群岛东部海域获得鱼卵数量、鱼卵种类数均最多,是江门沿岸海域日本鳀、龙头鱼的主要产卵场;黄茅海、镇海湾西部水域均未获得鱼卵,可能与水域环境变化及陆源污染导致产卵环境破坏、亲体量减少有关。该研究结果揭示了江门沿岸海域夏季鱼卵分布格局,为其制定有效的产卵场保护措施提供依据,同时表明DNA条形码技术能有效地对鱼卵进行种类鉴定,可被广泛地应用于我国沿海海域鱼卵鉴定工作。     

Studies on occurrence,characterisation and decontamination of emerging pathogenic Escherichia coli (STEC,ETEC and EIEC) in table eggs

1. Escherichia coli is one of the most common facultative anaerobic species present in the gastrointestinal tract of animals and human beings. Usually they occur as commensals, but some serotypes can cause significant illnesses in humans as well as mammals and birds.

2. The occurrence of E. coli in different categories of table eggs collected from markets was evaluated. Isolates were analysed for the presence of virulence genes, antibiotic susceptibility pattern and efficacy of peracetic acid and chlorine for the purpose of decontaminating table eggs.

3. Significant differences were observed in the occurrence of E. coli between different groups viz. processed (cleaned, washed, sanitised and packed eggs), unprocessed (un-cleaned, un-sanitised and loose eggs) and free range (eggs obtained from backyard poultry) table eggs. Overall, E. coli occurred in table eggs at 28.6% with 22.9, 29.2 and 50.0% occurrence in processed, unprocessed and free-range table eggs, respectively.

4. A total of 24 isolates of E. coli were obtained and screened for virulence genes viz. STH, SLT1/2 and INVE genes. Of the 24 isolates recovered, 10 typeable isolates belonged to O141, O119, O9, O120 and O101 serotypes, while the remaining 14 were untypeable. Antibiograms of the isolates showed multiple antimicrobial resistance (MAR) index in the range of 0.13–0.40.

5. Peracetic acid (PAA) and chlorine (CL) were studied for their sanitisation efficacy; concentrations of 100 mg/kg of PAA and 200 mg/kg of CL completely inactivated E. coli over the egg surface and also resulted in 2.58 and 2.38 log reduction in total viable counts (TVC), respectively.

6. The presence of virulence-associated shiga-like toxin (SLT1/2) and invasion E (INVE) genes and antimicrobial resistance among the emerging serotypes of pathogenic E. coli isolated from table eggs has public health implications. It underscores the need to implement better management practices across the production systems and marketing channels to produce E. coli-free wholesome eggs for consumers.     

漂流性鱼卵的孵化特性及水动力需求研究进展

鱼卵运动规律研究是鱼类产卵场位置推算、水库生态调度和鱼类资源保护的基础。对于产漂流性卵鱼类,当流水环境不足以维持鱼卵漂流时,鱼卵便下沉死亡而无法孵化成幼鱼。通过对照中国内陆鱼类名录,查阅国内重要流域及地方鱼类志中有关产漂流性卵鱼类的繁殖条件,梳理了典型鱼类的产卵水温、产卵时间和孵化时长等相关信息。针对现有鱼类志中对于鱼卵基本物理性质及鱼卵孵化所需水动力条件信息缺失的情况,补充查阅了国内外相关文献,归纳总结了漂流性鱼卵安全漂流的水动力条件。一种观点认为鱼卵在水体中是否能安全漂流取决于水体的流速,另一种观点认为控制漂流性鱼卵悬浮或下沉的关键参数是湍流状态或剪切速度,而不是水流的线速度,现有漂流性鱼卵孵化的关键水动力条件和阈值尚有争议,仍需加强鱼卵运动规律的相关试验研究。目前国内外对鱼卵的漂流输移研究方法和手段,主要采用野外监测、室内实验和模型模拟。已有研究大多只是针对鱼卵运动规律本身进行单一试验或模型验证,如何通过水库调度最大程度保障漂流性鱼卵的漂流孵化条件是未来鱼类保护的重要方向。     

Anti-Obesity and Gut Microbiota Regulation Effects of Phospholipids from the Eggs of Crab,Portunus Trituberculatus,in High Fat Diet-Fed Mice

There are resourceful phospholipids in the eggs of the crab, Portunus trituberculatus (Pt-PL). However, their components and bioactivities regarding obesity were unclear. Here, we investigated the composition of Pt-PL and their fatty acids. Moreover, its effects on obesity and gut microbiota were also evaluated in high fat diet (HFD)-fed mice. The results showed that Pt-PL contained 12 kinds of phospholipids, mainly including phosphatidylcholine (PC, 32.28%), phosphatidylserine (PS, 26.51%), phosphatidic acid (PA, 19.61%), phosphatidylethanolamine (PE, 8.81%), and phosphatidylinositol (PI, 7.96%). Polyunsaturated fatty acids (PUFAs) predominated in the fatty acids components of Pt-PL, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Animal experiments demonstrated that Pt-PL significantly alleviated body weight gain, adipose gain, hepatic gain, fasting blood glucose, serum insulin, lipid levels in serum and the liver, and systematic inflammation in HFD-fed mice. Furthermore, Pt-PL regulated gut microbiota, especially in a dramatic reduction in the ratio of Firmicutes to Bacteroidetes at phylum level, as well as significant amelioration in their subordinate categories. Pt-PL reduced fecal lipopolysaccharide and total bile acids, and elevated fecal short chain fatty acid (SCFA) concentrations, particularly acetate and butyrate. These findings suggest that Pt-PL possesses anti-obesity effects and can alter gut microbiota owing to the abundance of PUFAs. Therefore, Pt-PL may be developed as an effective food supplement for anti-obesity and regulation of human gut health.     

硝基苯代谢物在鸡蛋中的残留与消除

将120只罗曼褐蛋鸡随机分为三个处理组和一个对照组,每组30只,三个处理组的蛋鸡分别饮水投予25、50、100 mg.L-1三种剂量的硝基苯,对照组自由饮用自来水。连续染毒10 d,停止后继续观察8 d,每天收集蛋样,采用HPLC法测定鸡蛋中硝基苯代谢物。结果显示,连续给药10 d及停止染毒后蛋中只检测到氨基酚和硝基苯胺两种代谢物,停染后第8 d未检出。建议蛋鸡在误饮用含硝基苯水后应立即更换为洁净水,经过至少10 d的废弃期,鸡蛋方可食用。     

基于图像边缘识别的鸡蛋曲率测量

利用机器视觉获取鸡蛋截面图像,进行相应的图像处理后提取其边缘点坐标,用最小二乘法进行数据拟合,求取以三次多项式表示的曲线拟合方程,并将求得的拟合方程生成的曲线与原图像边缘进行了比较,其匹配度达99.22%,说明该曲线能反映鸡蛋的边缘曲线变化规律.通过拟合曲线的曲率图的变化,对鸡蛋的形状结构进行了分析,为进一步研究鸡蛋的特性提供了理论依据.     

植源性蜕皮激素对家蚕结扎蛹卵巢发育的诱导

探讨了植源性蜕皮激素对家蚕结扎蛹卵巢发育的诱导作用。结果表明:植源性昆虫蜕皮激素可以诱导结扎蛹卵巢发育形成成熟卵;其成熟卵,经人工单性生殖处理表明,具有和正常卵相同的生理活性。在蜕皮激素诱导结扎蛹卵巢发育的过程中,保幼激素类似物具有拮抗作用,影响卵巢的增重。在苏5、苏6、苏5×苏6、苏3×苏4的不同蚕品种间,诱导结扎蛹卵巢发育所需的蜕皮激素剂量无明显差异。