Food and feeding habits of Oreochromis mossambicus (Peters) in hypertrophic Hartbeespoort Dam,South Africa

The diet of 745 Oreochromis mossambicus (Peters) of less than 0,5 up to 2000 g wet mass, in Hartbeespoort Dam, was determined from stomach content analysis. Samples of fish were selected to cover a whole annual cycle. Small fish fed initially on zoobenthos and zooplankton, but fish with a mass of over 4 g fed increasingly on Microcystis aeruginosa Kutzing and detritus until these food items formed the dominant food source in O. mossambicus over 8 g. Some cannibalism was encountered in fish up to 64 g in the summer months. The ratio of intestinal length to total length of fish ranged from 0,58 in the smaller fish to 11,02 in larger fish and this indicated that there was an ontogenetic adaptation from a carnivorous to a phytoplanktivorous/detritivorous diet. Feeding in juvenile fish studied over 24 h was found to be most intense in the early morning and late afternoon but remained high throughout daylight hours decreasing considerably at night. The daily ingestion rate of food in O. mossambicus in Hartbeespoort Dam was estimated at 453 mg/g of fish. This comprised 45% M. aeruginosa and 55% detritus. It was apparent that of this matter ingested only a small percentage would be assimilated. Oreochromis mossambicus shows feeding and breeding preadaptations which enable it to successfully exploit a lacustrine environment. These adaptations enable it to maintain a large population in Hartbeespoort Dam despite frequent winter mortalities caused by water temperatures below their tolerance limits.     

Ontogenetic variation and craniometric sexual dimorphism in the social giant mole-rat,Fukomys mechowii (Rodentia: Bathyergidae), from Zambia

The degree of maxillary molar tooth-row eruption and wear were used to assign samples of the social giant mole-rat, Fukomys mechowii, from Zambia, into nine relative age classes in order to assess ontogenetic (age) variation and craniometric sexual dimorphism, with reference to body mass. Univariate and multivariate statistical analyses showed craniometric differences between age classes 1–3 and age classes 5–9, with age class 4 being intermediate between these two age class groupings. This suggests that age class 4 lies at a point on a hypothetical growth curve where growth begins to stabilize. The intermediate placement of age class 4 in multivariate space broadly coincided with body mass categorizations into juveniles (age classes 1–3; <100 g), subadults (age class 4; c. 100–150 g), and adults (age classes 5–9; >150 g). The analyses also revealed the absence of sexual dimorphism in the relatively younger age classes 1–4 but its presence in the relatively older age classes 5–9, and these results are supported by data on body mass. These results may have implications in our understanding of the population and social structures, and reproductive strategies in this little-studied giant mole-rat.     

2017年冬季斯科舍海南极磷虾种群结构变动研究

斯科舍海蕴含着丰富的南极磷虾资源,是重要的南极磷虾渔场,该海域南极磷虾种群结构存在显著的时空差异。为了解该海域冬季南极磷虾的种群结构变动,以明晰渔场的变化,并探究南极磷虾的越冬机制,利用2017年5—8月渔业资源调查随机收集的样本,对冬季布兰斯菲尔德海峡和南乔治亚岛东北水域南极磷虾种群结构差异进行分析。结果显示,2017年冬季各月南极磷虾性比差异不大,均为雌性占比稍高于雄性,且各月性成熟度分布不存在显著差异。总体而言,雌性磷虾在整个冬季月份,除个例外均为未成熟个体。对于雄性磷虾,5月未成熟个体少于成熟个体;6月未成熟个体多于成熟个体;7月未成熟个体显著多于成熟个体;8月均为未成熟个体。对于布兰斯菲尔德海峡和南乔治亚岛两区域,整体来说,随月份增加,磷虾雌、雄个体的成熟个体数量减少,而未成熟个体数量逐渐增加。通过历史资料对比可知,斯科舍海冬季磷虾种群结构存在较为显著的年际和年间变化。     

益肾活血汤联合缬沙坦治疗2型糖尿病合并男性性功能障碍的临床研究

目的 探讨益肾活血汤联合缬沙坦治疗2型糖尿病（type 2 diabetes mellitus,T2DM）合并男性性功能障碍患者的临床疗效及安全性。方法 将T2DM合并男性性功能障碍患者146例,按随机数字表法分为对照组和观察组,每组73例。对照组患者予缬沙坦胶囊口服,观察组患者加服益肾活血汤,4周为1个疗程,连续治疗3个疗程。观察治疗前后两组患者国际勃起功能障碍指数（International index of erectile dysfunction-5,IIEF-5）、阴茎勃起时间、阴茎头、根部平均硬度及血清性激素[促卵泡生成素（Follicle stimulating hormone,FSH）、黄体生成素（Luteinizing hormone,LH）、雌二醇（estradiol,E₂）和睾酮（testosterone,T）]水平变化;评估两组患者治疗后性生活满意度和不良反应发生率;比较两组患者治疗后临床总有效率。结果 观察组患者临床总有效率84.93%明显高于对照组的50.68%（P<0.05）;两组患者治疗后IIEF-5、阴茎勃起时间、阴茎头、根部平均硬度及血清T水平均较治疗前明显升高（P<0.05）,血清FSH、LH及E₂水平均显著下降（P<0.05）,且观察组各项指标的改善明显优于对照组（P<0.05）;观察组患者性生活总满意度91.78%明显高于对照组的68.49%（P<0.05）;两组患者在治疗期间均未出现明显不良反应。结论 益肾活血汤联合缬沙坦治疗T2DM合并男性性功能障碍临床疗效确切,能有效改善患者的阴茎状态和血清性激素水平,改善患者的性生活,安全性高,值得临床推广应用。     

北部湾多齿蛇鲻繁殖生物学特征

本研究基于2020年在北部湾海域采集的1214尾多齿蛇鲻（Saurida tumbil）样本,通过对生物学特征和卵巢组织学进行分析,探究该海域多齿蛇鲻种群的繁殖特性及其适应性变化。结果表明,2020年北部湾多齿蛇鲻雌雄性比为1.82:1,雌性群体成熟性腺4季均有分布,3~ 8月性成熟系数（GSI）保持较高水平,为主要繁殖期,其中3月和7月为繁殖高峰期;成熟卵巢中存在不同卵径大小的卵粒,卵径组成分布呈明显多峰型;绝对繁殖力波动范围较大（2774~ 158986粒）,且成熟卵巢中存在不同发育时相的卵母细胞,综合GSI、繁殖期、卵径分布及组织切片等结果推断多齿蛇鲻为分批非同步产卵型鱼类;相对繁殖力（267粒/g）保持在较高的水平,有利于其在高强度捕捞压力下迅速建立稳定种群;采用Logistic回归方程估算雌性群体的初次性成熟体长为19.0 cm,与性比随体长变化的重要转折点相同。本研究发现,北部湾多齿蛇鲻的繁殖特性相较以往结果有所改变,同时,研究结果进一步丰富了北部湾多齿蛇鲻的繁殖生物学资料,为渔业资源保护和可持续利用提供科学参考依据。     

Relationships between body size and secondary sexual characters,and sperm characters in male Dolly Varden char (Salvelinus malma)

In Salmonidae, subordinate males are exposed to higher risks of sperm competition than dominant males and thus are expected to improve the sperm characteristics (sperm concentrations, sperm velocity and sperm longevity). In this study, we investigated the relationships between body size and secondary sexual characters (breeding colour, hump height and snout length), and sperm characteristics of one‐year‐old (newly matured) Dolly Varden char. Small males displayed higher sperm concentrations than large males. Moreover, males with dull breeding colours, but not with lesser snout length and hump height, displayed an increased sperm velocity compared to males with bright colours, suggesting a trade‐off between sperm quantity and the investment in breeding colour. In addition, sperm longevity decreased as sperm swimming velocity increased. These findings indicate that small males with dull breeding colours improve the quantity and quality of their sperm to a great extent to enhance their chances of reproductive success.     

Seasonality in Saint Croix male lamb reproductive development in northern Mexico

The aim of this study was to determine the influence of the season of birth on the body weight, testicular size, testosterone concentrations, semen output and sexual behaviour in Saint Croix male lambs. Thirty‐three lambs were born in spring (n = 10), summer (Sum; n = 12) or autumn (n = 11). Body weight and the scrotal circumference were weekly recorded; semen was also weekly collected by electroejaculation; and sexual behaviour towards oestrous ewes was weekly evaluated. Data were recorded from 15 to 33 weeks of age. The reproductive development of Saint Croix male lambs differed according to the period in which they were born. More lambs born in spring than in summer and autumn achieved puberty during this study and were also more precocious in semen production and displayed sexual behaviour earlier. Lambs born in summer delayed their semen production; however, season‐related negative effects were less pronounced at the end of the study than in autumn born lambs born. In conclusion, despite the apparently low seasonality of the breed, Saint Croix male lambs showed in this study a seasonal pattern in their reproductive development at least until they achieve the puberty.     

遮阴和干旱对荩草克隆生长和有性繁殖及权衡关系的影响

以可建植边坡草坪的野生荩草为材料,设置遮阴(5个水平)和干旱(4个水平)交互形成的20个组合处理,测定克隆生长性状和有性繁殖数量及生物量结构,分析不同遮阴和干旱组合处理下克隆效率指数(CEI)、繁殖分配(RA)、繁殖效率指数(REI)、繁殖指数(RI)、繁殖比率(RR)的差异,研究遮阴和干旱对荩草克隆生长和有性繁殖及权衡关系的影响,结果表明:1)遮阴和干旱对克隆子株数及克隆效率指数有显著影响,中、重度干旱和≥10%遮阴显著降低了子株数(P<0.05),干旱对CEI无影响、遮阴降低了CEI,交互作用极显著降低了基株的子株数和CEI(P<0.01)。2)遮阴和干旱对母株、子株和基株的花穗数和小花数,对繁殖器官生物量(ROB)、非繁殖器官生物量(NROB)和总生物量(TB)有显著影响(P<0.05),轻、中度干旱或10%～30%遮阴或轻度遮阴和轻度干旱组合可显著增加母株、子株、基株的花穗数和小花数,轻度干旱或10%遮阴或轻度干旱和轻度遮阴组合可显著增加TB和ROB,交互作用是影响基株花穗数和小花数、TB、ROB和NROB的主要因子,干旱对TB和NROB影响次之,遮阴对ROB影响较大。3)遮阴和干旱对RA、REI、RI和RR有显著影响(P<0.05),轻中度干旱或10%遮阴可提高基株的繁殖参数,重度干旱或≥30%遮阴度降低了有性繁殖(P<0.05),轻度遮阴和轻度干旱组合比单一处理更利于有性繁殖,轻度干旱可缓解中重度遮阴对有性繁殖的影响,繁殖参数主要受交互作用影响,遮阴次之,干旱较小。4)荩草可依据遮阴和干旱胁迫程度,进行克隆生长和有性繁殖权衡,遮阴≥30%可延长克隆生长10～34d,中、重度干旱缩短克隆生长而促进有性繁殖,≥10%遮阴可缓解重度干旱对有性繁殖的影响(P<0.05)。5)20个遮阴和干旱组合处理下荩草均能同时维持两种繁殖方式,水分充足和全光照利于克隆生长,轻中度干旱和轻度遮阴单一或组合处理利于有性繁殖,遮阴和干旱交互影响增加了荩草的两种繁殖能力。     

猕猴脾脏中雌激素受体的表达及其性别差异

选取健康成年雌雄猕猴各3只,采用免疫组织化学SP法研究了雌激素受体(ER)在脾脏中的分布,观察猕猴脾脏中ER的表达及性别差异.结果显示,ER免疫阳性反应物主要分布于脾脏红髓区,脾小结相对较少,而动脉周围淋巴鞘、血管内皮、脾小粱等组织结构内仅有少量分布.ER阳性产物主要定位于细胞核中.部分存在于胞浆和胞膜上.雌性猕猴脾脏中的阳性细胞数量显著高于雄性,表达强度也较雄性强.这表明,ER参与雌激素对脾脏的免疫功能调控.ER阳性产物分布特点表明雌激素发挥作用主要是通过经典基因组机制,同时也通过非基因组机制途径.而ER表达的明显性别差异提示体内雌激素水平可能对脾脏中B淋巴细胞的功能有正调节作用.     

Shrinking baseline: the growth in juvenile fisheries,with the Hong Kong grouper fishery as a case study

Historic and current information on the grouper fishery from Hong Kong and adjacent waters reveals significant changes in species composition and fish sizes over the past 50 years in this important Asian centre for seafood consumption. Once dominant, large groupers are now rare and small species and sizes prevail in the present‐day fishery. Juveniles comprise over 80% of marketed fish by number among the most commonly retailed groupers, and reproductive‐sized fish are absent among larger species. Current fishery practices and the lack of management in Hong Kong and adjacent waters pose a significant threat to large species with limited geographic distribution such as Epinephelus akaara and Epinephelus bruneus, both now listed as threatened by the IUCN. The heavy reliance on juveniles, not only for groupers, but for an increasing diversity of desired fishes within Asia, potentially reduces stock spawning potential. The ‘shrinking baseline’ in terms of a progressive reduction in fish sizes being marketed in the region can seriously undermine fishery sustainability and recoverability of depleted fish stocks. Fishing pressure on groupers and other valuable food fishes within the Asia‐Pacific is intensifying, the declining long‐term trend of grouper landings in Hong Kong and the increasing focus on juveniles for immediate sale or for mariculture ‘grow‐out’ signal a worrying direction for regional fisheries. Moreover, the common appearance of small groupers for sale will influence public perception regarding what are ‘normal‐sized’ fish. Management attention is needed if these fisheries are to remain viable.