Effects of age and sex ratios on offspring recruitment rates in translocated black rhinoceros

Success of animal translocations depends on improving postrelease demographic rates toward establishment and subsequent growth of released populations. Short‐term metrics for evaluating translocation success and its drivers, like postrelease survival and fecundity, are unlikely to represent longer‐term outcomes. We used information theory to investigate 25 years of data on black rhinoceros (Diceros bicornis) translocations. We used the offspring recruitment rate (ORR) of translocated females—a metric integrating survival, fecundity, and offspring recruitment at sexual maturity—to detect determinants of success. Our unambiguously best model (AICω = 0.986) predicted that ORR increases with female age at release as a function of lower postrelease adult rhinoceros sex ratio (males:females). Delay of first postrelease reproduction and failure of some females to recruit any calves to sexual maturity most influenced the pattern of ORRs, and the leading causes of recruitment failure were postrelease female death (23% of all females) and failure to calve (24% of surviving females). We recommend translocating older females (≥6 years old) because they do not exhibit the reproductive delay and low ORRs of juveniles (<4 years old) or the higher rates of recruitment failure of juveniles and young adults (4–5.9 years old). Where translocation of juveniles is necessary, they should be released into female‐biased populations, where they have higher ORRs. Our study offers the unique advantage of a long‐term analysis across a large number of replicate populations—a science‐by‐management experiment as a proxy for a manipulative experiment, and a rare opportunity, particularly for a large, critically endangered taxon such as the black rhinoceros. Our findings differ from previous recommendations, reinforce the importance of long‐term data sets and comprehensive metrics of translocation success, and suggest attention be shifted from ecological to social constraints on population growth and species recovery, particularly when translocating species with polygynous breeding systems.     

Reproductive ecology of the pond turtle (Emys orbicularis L.) in the Northeastern part of the species range

In Belarussian Polesye, characteristics of reproduction, population dynamics, and factors responsible for a decrease in the abundance of the pond turtle were studied. The main factors limiting pond turtle reproduction in Polesye include the focal distribution of its populations and limited areas of reproductive biotopes. The pond-turtle popuation itself is characterized by a high potential for reproductive growth; in the current situation, the population growth is mainly limited by a high pressure of oophagous predators and anthropogenic destruction of reproductive sites.     

Long-Term Changes in the State of Gonads in Sea Urchins Strongylocentrotus intermediusfrom Amur Bay,the Sea of Japan

The state of gonads was analyzed in sea urchins Strongylocentrotus intermediuscollected in Amur Bay (Peter the Great Bay, the Sea of Japan) in August 1984, 1985, 1989, and 1997 at five stations: Skrebtsov Island (1), Sportivnaya Harbor (2), Cape Tokarevskii (3), Alekseev Bay on Popov Island (4), and Verkhovskii Islands (5). The first three stations were in the polluted inshore zone of Vladivostok; stations 4 and 5 were in the open (insular) part of the bay, remote from the main sources of pollution. The state of gonads of sea urchins collected in different years and areas strongly varied with respect to gonad index (GI), gonad maturity index, and indices of pathological changes in gonads. As compared with the data obtained in 1984, 1985, and 1989, the values of GI increased in sea urchins from stations 1–3 and decreased in sea urchins from stations 4 and 5. Although GI values were high, the indices of gonad maturity in animals from the coastal zone were very low. In general gonad maturity in sea urchins from the Amur Bay was lower in 1997 than in the previous years. The correlation analysis of long-term data revealed no positive correlation between the values of GI and gonad maturity index in sea urchins from stations 1–4. Histopathological changes were more serious in sea urchins from stations 1–3. In 1997, the indices of pathological changes in the gonads of sea urchins from the insular zone (stations 4 and 5) were higher than in the previous period (1984–1989). The influence of various ecological factors—temperature, salinity, environmental pollution, and food supply—on gametogenesis in sea urchins is discussed.     

泥鳅在污染物毒性评价中的应用研究

泥鳅营底栖生活,生存能力强,易于饲养,便于采集和处理,有作为模式生物的潜力。受到污染物胁迫时,泥鳅在分子、细胞、组织、器官和个体水平上会发生明显的变化,其存活、生长和繁殖从而受到影响。泥鳅的这些特性可以被用来进行污染物毒性评价。从急性毒性、蓄积毒性、生殖力毒性、遗传毒性等方面,综述和分析了泥鳅在污染物毒性评价中的应用研究进展,并对未来研究重点进行了展望。     

木黄酮对鱼类毒性作用的研究进展

木黄酮是一种主要存在于大豆等豆类植物中的雌激素类似物,在预防和治疗一些与代谢综合征及癌症相关的疾病,如更年期综合征、糖尿病、乳腺癌、前列腺癌,发挥着重要作用。近年来,其在工业、农业、水产养殖业等方面应用越来越广泛,排放到环境中的木黄酮也越来越多,它在环境中的作用以及对环境中生物的影响也逐渐得到关注。由于木黄酮通常与废水一起排入水体中,因此受到影响的主要是以鱼类为代表的水生生物。木黄酮对鱼类的毒性作用主要表现在生殖系统,具体表现为抑制性腺发育、影响生殖细胞形成,改变性激素水平等,同时对其他器官和系统也会有不同程度的影响。水体中的木黄酮由于具有比人类饮食中更低的生物利用度和更高的浓度而成为一种环境内分泌干扰物,会对水生生物,尤其是各种鱼类的生存和繁殖产生不利影响。本文拟从生殖发育、心血管形成、神经功能、肝脏代谢等方面,综合阐述木黄酮对鱼类的生物毒性效应,并重点关注其对生殖系统的毒性效应。     

基于模式生物秀丽隐杆线虫的环境污染物生殖毒性研究进展

由于人类社会的发展,环境污染也越来越严重,研究环境污染物对生态及人类健康的影响极为重要。生殖系统是人和动物繁衍后代的重要系统,常见环境污染物对生殖系统的影响正引起研究人员的广泛关注。秀丽隐杆线虫具有身体透明、品系丰富和遗传背景清楚等优点,为生殖毒理学研究提供了一个便利的平台。以秀丽隐杆线虫为模型已对多种环境污染物的生殖毒性进行了评价。本文重点叙述了重金属、纳米材料、有机物等化学污染,辐射、磁场等物理污染,以及病毒等生物污染对秀丽线虫生殖系统的影响,并归纳讨论了环境污染物造成生殖功能障碍的几种主要机制,如氧化应激、DNA损伤、内质网应激以及神经损伤等,但不同类型污染物的毒性效应与其自身的物化性质紧密相关。环境污染物诱导的生殖毒性中不同响应机制之间的关联性、不同发育阶段的敏感性差异、污染物的传代效应以及有效的缓解方式的筛选等都有待进一步的开展。     

苯并芘对生殖系统的毒性作用及其机制研究进展

苯并芘（benzo （a） pyrene,BaP）作为多环芳烃（polycyclic aromatic hydrocarbons,PAHs）的成员,是最早发现也是最具有代表性的环境污染物,通过空气、食物、水源等途径进入人体,引起细胞氧化应激损伤、DNA损伤和基因异常表达导致细胞死亡。研究表明雄性与雌性动物经BaP染毒后,其生殖器官、生殖细胞甚至激素水平均会受到影响,进而影响受精卵形成和胚胎发育,造成不良妊娠结局。因此,近年来BaP的生殖毒性受到广泛关注,其作用机制包括改变胞内活性氧水平、诱导细胞DNA损伤以及调控生殖发育相关基因、类固醇合成相关基因和促凋亡基因影响生殖发育。BaP作为环境毒物,不仅可以影响生态环境的稳定性,还可以影响生物的生殖发育,损害生态环境中的物种多样性,从长远来看,BaP的不良影响不但会威胁到陆地与海洋生物种群的稳定,还会破坏陆地和海洋生态系统的功能。本文将从生殖健康、配子与合子形成以及胚胎发育的角度,详细阐述BaP染毒对生殖系统的毒性作用与机制,为预防BaP引起的生殖危害、减少不良妊娠结局提供理论依据,旨在为BaP的环境毒性行为和对生物的毒性研究提供有效借鉴,为合理预防和缓解因接触BaP等环境毒物而带来的健康影响提供参考。     

氯虫苯甲酰胺及其代谢物IN-EQW78对蚯蚓氧化应激及繁殖能力的影响

为明确氯虫苯甲酰胺(CAP)及其代谢物氯虫苯甲酰胺脱水环化物(IN-EQW78)对蚯蚓毒性效应的差异,开展了 CAP和代谢物IN-EQW78对蚯蚓的56 d单一暴露实验,探讨2种化合物分别对蚯蚓氧化应激及繁殖能力的影响.结果表明,5 mg·kg-1的CAP暴露14 d后,过氧化氢酶(CAT)活性显著上升,超氧化物歧化酶(SOD)活性在28 d时明显增强;IN-EQW78暴露7 d后,SOD和谷胱甘肽转移酶(GSH-ST)活性增强,而CAT活性降低.IN-EQW78比CAP会更早地引起蚯蚓氧化应激效应,并引发更大的氧化损伤.5 mg·kg-1的CAP处理减少了蚯蚓精子数量,破坏卵巢结构,对生殖系统造成损伤,并进一步抑制蚯蚓繁殖,导致56 d时幼蚓数量显著下降;而IN-EQW78(≥0.04 mg·kg-1)处理对卵巢无损伤,反而引起蚯蚓精子数量增加,从而促进蚯蚓繁殖,显著提高了 56 d时幼蚓及蚓茧数量.本研究揭示了 CAP及其代谢物对蚯蚓的潜在影响,为农业生产中CAP的风险评估提供了科学依据.     

双酚A对哺乳类实验动物雄性生殖系统发育的影响

内分泌干扰物双酚A（bisphenol A,BPA）对生殖系统尤其是雄性生殖系统的影响一直受到关注,然而目前相关研究中存在诸多不一致的结果。本文系统分析了低剂量BPA对哺乳类实验动物大鼠和小鼠雄性生殖系统发育影响的文献,重点关注睾丸和附睾的质量、睾丸组织学结构、附属腺和外生殖器参数、肛殖距、精子参数和性激素水平等指标的变化,并探讨了实验结果与实验设计某些因素的相关性。经分析发现,妊娠期BPA暴露对实验鼠雄性生殖系统的影响呈现比较一致的阳性结果,但是哺乳期暴露和妊娠至哺乳期的暴露存在很多矛盾的结果;而动物品系、给药方式等因素与实验结果之间没有明确的关系,即便相似甚至相同的实验设计下也出现了不同的结果。进一步分析发现,有些研究在实验质量控制方面存在一定的缺陷,这可能是造成矛盾结果的主要原因。综合来看,BPA在器官水平和组织病理学水平对雄性生殖系统发育的影响较弱,基于此类指标的效应判断容易受到实验设计因素和质量控制的影响,最终可能导致不一致的结果。由此建议,今后相关研究在加强质量控制的同时,应重点关注BPA对细胞和分子层面的损伤。     

长江口纹缟虾虎鱼的繁殖生物学特征

研究了长江口水域纹缟虾虎鱼的繁殖生物学。结果如下：(1)纹缟虾虎鱼雌雄亲鱼间形态学特征具有差异,肥满度分别为347±036与217±052,体长/体高、体长/头长、头长/眼径、头长/眼间距等比值存在极显著差异;(2)纹缟虾虎鱼产卵期为3~7月份,盛产期为4~6月份。绝对生殖力平均为12 6892粒,体长相对生殖力平均为2069粒/mm;(3)纹缟虾虎鱼成熟的卵为球形,卵径0482~0606 mm,卵中油球数量10~200个,精子较小,由圆形头部和细长尾部（鞭毛）两个部分组成;(4)纹缟虾虎鱼产卵受精一般在洞穴内进行,而且雄鱼具有护卵习性;(5)纹缟虾虎鱼受精卵呈梨形或者梭形,卵膜端具有由粘丝组成的附着盘,动物极靠近附着盘。纹缟虾虎鱼人工催产与自然繁殖时的受精率分别为7858%与8384%。在17~25℃范围内,纹缟虾虎鱼胚胎均能孵出仔鱼,随着水温上升发育速度加快,温度与孵化时间呈正相关关系,有效积温为3 1283 h·℃。长江口水域生态环境变动可能对纹缟虾虎鱼繁殖及其资源量产生一定影响。