不同多疣壁虎种群繁殖特征的比较

对浙江地区3个多疣壁虎(Gekko japonicus)种群的个体大小、繁殖生活史特征进行了测定。在24 ℃、28 ℃和31 ℃条件下,孵化多疣壁虎卵,并测定其孵化期和幼体特征。结果表明：多疣壁虎成体存在显著种群间变异和两性差异,即衢州和温州个体大于杭州个体,雌体大于雄体;卵平均质量和窝卵重无显著种群间差异,但杭州壁虎的相对窝卵重显著大于衢州和温州个体;孵化温度能显著影响孵化期及幼体的尾长和头宽,但不影响幼体体长、体质量及运动能力;孵化温度效应不存在种群间差异。本研究揭示了疣壁虎个体大小、繁殖输出以及卵孵化特征的微地理变异。     

拟长毛钝绥螨与硃砂叶螨相互作用的实验研究——干扰作用和搜寻效率

在猎物卵不同密度下,拟长毛钝绥螨(Amblyseius pseudolongispinosus)随其种群密度的增加(不超过10头/叶片),个体之间不存在干扰作用;捕食螨的搜寻活动和产卵分布对猎物分布的变动有一定的时滞性;聚集行为往往是由于某些生境中猎物被消耗殆尽后引起的,这与捕食螨在猎物卵不同密度下的扩散作用和干扰作用较弱有关。     

小种群的遗传变异和近交衰退

小种群一般拥有较小的遗传变异.当前人为干扰和破坏造成了生物种群个体数量减少,导致种群遗传多样性丧失,引起近交衰退,影响到种群后代适应性.产生近交衰退的原因是近交增加了有害等位基因纯合几率,导致个体适应能力下降.近交衰退受交配系统、世系效应、环境胁迫等的影响.在物种保护和恢复过程中,要防止近交衰退.     

大凉螈繁殖生态

大凉螈是我国特有的珍稀有尾两栖动物,其种群数量目前呈现明显下降趋势,然而涉及该物种保护的繁殖生态学研究仍十分匮乏。通过融合围栏陷阱及标志重捕的样方调查法,对大凉螈石棉栗子坪种群繁殖个体和变态登陆幼体的迁徙、繁殖群体种群大小、繁殖场内雌雄有效性比变化等进行了研究。运用Jolly-Seber法估测了繁殖种群大小,运用单因素方差分析或Kruskal-Wallis秩和检验比较了不同时期进入繁殖场的雄性大凉螈头体长及体重,运用t检验或者Wilcoxon秩和检验比较了雌雄性间形态上的差异,运用t检验、t′检验或Wilcoxon秩和检验比较了野外抱对雄性与非抱对雄性间的体征差别,运用Pearson相关分析探讨了雌性产卵量与其身体形态的关系,同时观察了卵的孵化情况。研究结果表明:大凉螈的繁殖季为每年的4月下旬到7月下旬,幼体最早于8月上旬变态登陆。估测调查地繁殖场内雄性大凉螈繁殖种群大小约为391尾,雄螈较雌螈更早进入繁殖场且在场内停留时间更长,体重较轻的雄螈较晚迁入繁殖场。有效性比明显偏雄(雌/雄:0.03—0.10)。雌雄间具明显性二型性,雌性个体的头体长、体重及肥满度均大于雄性,而雄性的尾高和尾长占全长的比例则大于雌性。对比自然抱对雄性和非抱对雄性个体发现,抱对个体在头体长、体重和尾高等体征方面显著大于非抱对个体,暗示这些形态特征可能在雄性竞争配偶的过程中起到关键作用。雌螈在室内条件下平均产卵数为176枚,产卵历时2—4 d,产卵量与雌性肥满度正相关,卵的平均孵化期为15.7 d,孵出幼体平均全长为9.74 mm。     

中国石龙子雌体繁殖特征和卵孵化的地理变异

浙江丽水和广东韶关中国石龙子均年产单窝卵,窝卵数,窝卵重和卵重均与雌体SVL呈正相关,雌体头部形态,繁殖特征,产卵起始时间和孵孵化的热依赖性等有显著的地理变异;韶关石龙子产卵起始时间为5月中旬,比丽水经子约早两周,韶关石龙子窝卵数较大,卵较小,窝卵重与丽水石龙子无显著差异。韶关石龙子特定SVL的窝卵数比丽水石龙子多2．8枚卵,中国经子卵数量和大小之间有种群间权衡,无种数内权衡,同一种群内卵数量与卵大小无关,孵化温度影响石龙子孵出幼体的一些特征,24℃孵出细幼体比32℃孵出幼体大,躯干发育好,剩余卵黄少,韶关24℃孵出幼体的体重,躯干干重小于丽水幼体,韶关32℃孵出幼体的SVL小于丽水幼体,剩余卵黄大于丽水幼体,表明适宜卵孵化温度范围有地理变异。丽水石龙子卵对极端高温和低温的耐受性较强,适宜卵孵化温度范围较宽。     

三种前鳃亚纲海产腹足类性畸变现象的组织学研究

有机锡污染可以导致海产腹足类雌性个体产生性畸变现象。本文报道了阿文绶贝(Mauritia arabica)、褐棘螺(Chicoreus brunneus)和桶形芋螺(Conus betulinus)三种前鳃亚纲腹足类正常雄性个体和性畸变个体雄性生殖器官的组织学结构。结果表明,不同种间雄性个体的输精管和阴茎的结构存在开放和封闭两种类型,封闭型是由开放型进化而来。虽然性畸变个体的雄性生殖器官与正常雄性个体的在组织结构上无明显差异,但性畸变个体的雄性生殖器官并不完整,无法行使生殖功能。由于内分泌扰乱物质对人和动物影响的相似性,使得海产腹足类性畸变现象应受到人们的重视。     

甲壳动物性别分化的遗传决定及外界因素的影响(英文)

本文综述了甲壳动物的性别决定机理及外界因素对性别分化的影响。绝大多数甲壳动物没有明显的性染色体 ,促雄腺被认为是甲壳动物性别分化的最主要的决定因子 ,其作用已得到了广泛的证明。由于甲壳动物幼体在早期发育过程中具有向两性发育的潜能 ,促雄腺可以决定个体未来发育的性别 ,并且通过人为摘除或移植促雄腺的方法可以使性别已经分化的个体发生性逆转 ,从而改变幼体的性别。虽然甲壳动物的性别是由遗传决定的 ,但外界的因素比如寄生、光周期、温度或激素可以改变其性比 ,其中以寄生的影响研究比较多 ,并认为是影响某些甲壳动物性别分化的主要外界因子。由于大多数养殖的甲壳动物雌雄性之间有体重和体长的差异 ,在水产养殖中可以利用这些特征进行全雌或全雄种苗的生产 ,以提高产量和效益。     

三疣梭子蟹胚胎发育过程中肝胰腺的发生与卵黄物质利用的关系

通过对三疣梭子蟹胚胎进行连续采样和组织切片,系统研究了三疣梭子蟹胚胎发育过程中卵黄囊和肝胰腺的发生与卵黄物质利用的关系。结果表明:(1)三疣梭子蟹胚胎的卵黄岛和卵黄囊结构分别出现在原肠期和无节幼体期,胚胎从原肠期至卵内第一期溞状幼体期,始终存在卵黄岛结构,且卵黄岛中的卵黄物质不断被分解和利用. (2)卵内第二期溞状幼体后,卵黄囊分为两个区域,卵黄囊壁中出现肝胰腺细胞(柱状上皮细胞),此时肝胰腺前体已开始形成,卵黄岛开始融合. (3)卵内第三期溞状幼体阶段,卵黄囊发育成一双肝胰腺,由于肝胰腺中的卵黄物质互相融合,卵黄岛结构消失。此阶段胚胎对卵黄物质的利用加快, 卵黄物质中存在许多空泡状结构;(4)胚胎发育进入孵化前期后,肝胰腺腔内的卵黄物质极少,而初孵溞状幼体肝胰腺腔内卵黄物质已完全消失,肝胰腺为一对囊状结构。这些结果表明在三疣梭子蟹胚胎发育从原肠期到孵化前的过程中,卵黄岛和肝胰腺细胞对于卵黄物质分解和利用起着十分重要的作用。     

鲁中山区东亚三角头涡虫有性生殖过程研究初报

于2005年3-5月、9～11月对生活于鲁中山区的东亚三角头涡虫（Dugesia japonica）的有性生殖过程进行了研究,发现鲁中山区东亚三角头涡虫1年只有1次有性生殖过程。卵囊产出的高峰在4月,卵囊孵化与种群密度最高峰在5月,其有性生殖过程与温度、食物、虫体大小密切相关。经实验观察1个卵囊最多能孵出涡虫幼体10条,最少3条。     

孵化温度对黄喉拟水龟胚胎发育和幼体特征的影响

用3个恒定温度(24、26和28℃)孵化黄喉拟水龟南方种群卵,检测孵化温度对孵化期、孵化成功率和孵出幼体特征的影响。孵化温度显著影响孵化期和孵化成功率、以及幼体的性别、大小和早期生长。黄喉拟水龟幼体的性别取决于孵化温度(属TSDⅠa型),26℃和28℃孵出幼体偏雄性,30℃孵出幼体都是雌性。随着孵化温度的升高,孵化期呈非线性缩短,而孵化成功率略微增加。较高温度下孵出的幼体较大且具有较好的功能表现,但生长较慢。低温孵出幼体较小,但胚后生长速率较快。低温孵出幼体较小可能与胚胎发育期长、总代谢消耗大有关;而生长速率快则可能是因为低温产生的雄性幼体生长快于高温产生的雌性幼体。与已报道的黄喉拟水龟北方种群卵孵化结果相比较,26℃和28℃条件下南方种群卵的孵化期和产生1∶1性比的关键温度较大。这种地理上的变异可能反映不同种群对当地热环境适应性上的差异。     

Isolation and characterization of microsatellite loci from rock shell, Thais clavigera

Imposex (superimposition of male genital organs on female phenotype) of the rock shell or whelk, Thais clavigera, shows typical evidence of endocrine disruption by organotin compounds within inter-tidal zones polluted by such compounds. It will be informative to see how low fertility caused by imposex of this species finally affects the genetic diversity of polluted populations. For future use in population genetic research of the rock shell, we report the isolation and characteristics of 11 highly polymorphic microsatellite markers with a mean of 11.7 alleles per locus. We observed heterozygosities of these sequences ranging from 0.43 to 0.95. These markers will be useful for future ecological genetic studies of rock shell.     

Toxicity monitoring of endocrine disrupting chemicals (EDCs) using freeze-dried recombinant bioluminescent bacteria

Five different freeze-dried recombinant bioluminescent bacteria were used for the detection of cellular stresses caused by endocrine disrupting chemicals. These strains were DPD2794 (recA::luxCDABE), which is sensitive to DNA damage, DPD2540 (fabA::luxCDABE), sensitive to cellular membrane damage, DPD2511 (katG::luxCDABE), sensitive to oxidative damage, and TV1061 (grpE::luxCDABE), sensitive to protein damage. GC2, which emits bioluminescence constitutively, was also used in this study. The toxicity of several chemicals was determined on the first four freeze-dried bacteria, while nonspecific cellular stresses were measured using GC2. Damage caused by known endocrine disrupting chemicals, such as nonyl phenol, bisphenol A, and styrene, was detected and classified according to toxicity mode, while others, such as phathalate and DDT, were not detected with the bacteria. These results suggest that endocrine disrupting chemicals are toxic in bacteria, and do not act via an estrogenic effect, and that toxicity monitoring and classification of some endocrine disrupting chemicals may be possible in the field using these freeze-dried recombinant bioluminescent bacteria.     

Determining Indicators of Exposure and Effects for Endocrine Disrupting Chemicals (EDCs): An Introduction

Endocrine disruptors are characterized by their influence on animal endocrine systems resulting in reproductive, developmental, neurological, and immune dysfunction. The purpose of this overview is to provide the reader with a sense of the activities within the U.S. Environmental Protection Agency (USEPA), in particular NHEERL, that address the many facets of research on endocrine disrupting chemicals (EDCs) and to highlight the approach being taken at the different organizational levels within the USEPA, including screening, testing and evaluating endocrine disrupting chemicals. As a part of this endeavor, the USEPA continues to evaluate the current research activities in order to better understand and refine the process of risk characterization of EDCs. Thus, the participants in this session were asked to review their research within the framework of a better identification of EDC effects, better characterization of those compounds that have endocrine disrupting activity and how to incorporate this information into the risk assessment paradigm. Specifically, the goals of the ensuing papers were to compare individual vs. population indicators of endocrine disrupting effects, examine comparable and multiple mechanisms of toxicity, and describe the use of effects as indicators to identify toxicants and their sources. Mammalian and fish reproductive endpoints served as models to emphasize commonalities between human and wildlife risks.     

Detection of endocrine disrupters: evaluation of a Fish Sexual Development Test (FSDT)

Managed by the Organisation for Economic Co-operation and Development (OECD), a comprehensive work is carried out in numerous laboratories to develop test guidelines for the detection of endocrine disrupting chemicals in humans, and various animal species. Development of tests to detect chemicals with endocrine disrupting properties in fish is a part of that work. A Fish Sexual Development Test (FSDT) (an extension of the existing OECD TG 210, fish early life stage toxicity test), proposed as an international test guideline for the detection of endocrine disrupting chemicals, was evaluated by water exposure of juvenile zebrafish to the three natural estrogens: estrone, 17beta-estradiol, and estriol and the synthetic androgen trenbolone (trenbolone acetate). As endpoints, vitellogenin induction and histological changes including changes in sex ratios were investigated. The sex ratio was significantly altered towards females from 49 ng/l estrone, 54 ng/l 17beta-estradiol and 22 microg/l estriol, respectively. An all male population was observed from exposure to 9.7 ng/l trenbolone and above. Significant vitellogenin induction in whole body homogenate was measured after exposure to 14 ng/l estrone, 54 ng/l 17beta-estradiol and 0.6 mug/l estriol, respectively. Significant vitellogenin reduction was measured after exposure to 193 ng/l trenbolone or higher. The present results provide strong evidence that the FSDT is a sensitive test toward estrogenic and especially androgenic exposure and the validation of the FSDT as an OECD test guideline should continue.     

Identification of endocrine disrupting chemicals acting on human aromatase

Human aromatase is the cytochrome P450 catalysing the conversion of androgens into estrogens playing a key role in the endocrine system. Due to this role, it is likely to be a target of the so-called endocrine disrupting chemicals, a series of compounds able to interfere with the hormone system with toxic effects. If on one side the toxicity of some compounds such as bisphenol A is well known, on the other side the toxic concentrations of such compounds as well as the effect of the many other molecules that are in contact with us in everyday life still need a deep investigation. The availability of biological assays able to detect the interaction of chemicals with key molecular targets of the endocrine system represents a possible solution to identify potential endocrine disrupting chemicals.Here the so-called alkali assay previously developed in our laboratory is applied to test the effect of different compounds on the activity of human aromatase. The assay is based on the detection of the alkali product that forms upon strong alkali treatment of the NADP⁺ released upon enzyme turnover. Here it is applied on human aromatase and validated using anastrozole and sildenafil as known aromatase inhibitors. Out of the small library of compounds tested, resveratrol and ketoconazole resulted to inhibit aromatase activity, while bisphenol A and nicotine were found to exert an inhibitory effect at relatively high concentrations (100 μM), and other molecules such as lindane and four plasticizers did not show any significant effect. These data are confirmed by quantification of the product estrone in the same reaction mixtures through ELISA.Overall, the results show that the alkali assay is suitable to screen for molecules that interfere with aromatase activity. As a consequence it can also be applied to other molecular targets of EDCs that use NAD(P)H for catalysis in a high throughput format for the fast screening of many different compounds as endocrine disrupting chemicals. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone.     

New insights into the mechanism of imposex induction in the dogwhelk Nucella lapillus

In an attempt to clarify the mechanism(s) of tributyltin-mediated imposex induction in females of the neogastropod Nucella lapillus, dogwhelks collected in an almost imposex free population were exposed to several treatments for a 3 month-period, and the effects on imposex induction and testosterone/estradiol levels were evaluated. As a positive control, tributyltin (50 ng TBT Sn/L) clearly induced imposex and led to a significant increase in the severity of the phenomenon. In contrast, although a selective P450 aromatase inhibitor (formestane at 0.3 mg/L) was capable of imposex induction, it failed to increase its severity. A vertebrate androgen receptor (AR) antagonist (cyproterone acetate at 1.25 mg/L) in combination with TBT completely blocked the imposex induction capacity of TBT. On the other hand, an estrogen receptor antagonist (tamoxifen at 0.3 mg/L) rendered no effect. The determination of steroid levels in female specimens revealed that TBT induces an elevation of free testosterone (but not the total amount, free+esterified), while the co-administration of the anti-androgen and TBT was able to rescue the increase of free testosterone levels. Despite a minor decrease in the amount of testosterone-fatty acid esters in the TBT group, significant differences in esterified testosterone were not found among treatments. On the contrary, free estradiol levels were elevated in the TBT, anti-androgens and TBT plus anti-androgens groups. These results indicate that free estradiol biosynthesis in TBT-exposed females does not seem to be affected. Overall, our results demonstrate that a selective aromatase inhibitor can induce imposex in N. lapillus but not to a similar extent of TBT, which may suggest the involvement of other mechanism in imposex induction, besides aromatase inhibition. Additionally, the study points to the involvement of AR receptors in imposex induction.     

Effects of 4-n-nonylphenol and 17beta-oestradiol on early development of the barnacle Elminius modestus

Pollutants that are present in the aquatic environment and cause abnormal endocrine function in wildlife populations have been termed endocrine disrupting chemicals (EDCs). The impacts of these chemicals on the reproduction and development of vertebrates has been shown to be significant in both field studies and laboratory experiments. Over the past decade the number of investigations into the impacts of EDCs that affect reproductive and sexual characteristics (reproductive EDCs) has increased and evidence of their potency is evident in numerous wildlife species and through data from in vitro tests. However, little information is available on whether chemicals which act as EDCs in vertebrate species affect aquatic invertebrates. The case of imposex in archeogastropods following exposure to tributyltin (TBT) is a notable exception. Moreover, a number of studies have shown that development, fecundity and reproductive output of some aquatic invertebrates are affected significantly by exposure to pollutants. In order to determine whether external signs of exposure to vertebrate EDCs can be observed and monitored in invertebrate species, we exposed larvae of the barnacle Elminius modestus to environmentally realistic concentrations of the xeno-oestrogen, 4-n-nonylphenol (NP), and the natural oestrogen, 17beta-oestradiol (E(2)). Early life stages (nauplii and cyprids) were also exposed in the laboratory to determine whether there were effects on the timing of larval development and settlement. Ovary development and size of juveniles was measured following chronic exposure. Exposure to NP in the concentration range 0.01-10 μg l(-1) resulted in disruption of the timing of larval development. Similar results were obtained with E(2). Pulse exposures showed that the timing of exposure is critical and exposures for a period of 12 months caused long-term effects. A linear, concentration-dependent response was not evident.     

环境污染对几类水生无脊椎动物内分泌功能扰乱的研究现状

近年来，在环境毒理学这门边缘学科中又诞生了一个新的领域，即环境污染对内分泌功能的扰乱。研究发现，许多人工合成的杀虫剂和工业化合物能够扰乱脊椎动物的内分泌功能，这些化合物也存在于水环境中。近年来，这些环境有机污染物是否对水生无脊椎动物的内分泌功能同样具有扰乱作用成了环境内分泌学这个新领域的热点之一。由于近年来的研究侧重于腔肠动物、轮虫、软体动物、甲壳动物及棘皮动物，因此，本文主要介绍有关环境污染物对这几类水生无脊椎动物内分泌功能扰乱的研究进展。另外，对环境污染对水生无脊椎动物内分泌扰乱这个研究热点的现状以及今后的发展方向进行了评述。在从事环境污染对无脊椎动物内分泌功能影响的研究时，研究者必须意识到无脊椎动物和脊椎动物在内分泌机制上的差异，不可随意地在这两大类动物类群之间互相引伸研究结果。     

Physiological and Biochemical Analysis of Factors in the Female Venom Gland and Larval Salivary Secretions of the Ectoparasitoid Wasp Eupelmus orientalis

The stinging adult female and the biting newly-hatched larva of the solitary ectoparasitoid wasp Eupelmus orientalis can both cause permanent paralysis and stop the development of Callosobruchus maculatus host larvae. These two processes of host envenomation appeared to be independent and complementary in primary parasitism or in hyperparasitism of a distantly related hymenopteran host species. In contrast, the development of larvae as hyperparasites on members of their own species or genus depended completely on the prior injection of female venom. The venoms of the female and the first instar larva had similar effects on the cellular metabolism of the primary hosts. Protein synthesis was blocked in C. maculatus hosts envenomated by a female or a first instar larva of E. orientalis, but the absence of DNA breakdown indicated that these paralysed hosts were alive and quiescent. The venomous secretions injected by adult females and first instar larvae of E. orientalis had distinct electrophoretic profiles. The immunoreactive features of proteins from female venom and larval secretions were also examined. There is evidence for antigenic conservation between some venom proteins of E. orientalis and Apis mellifera. Lastly, the hyaluronidase, phospholipase and lipase activities in the female venom gland and in larval-derived secretions of E. orientalis were assayed. No lipase activity was detected. Phospholipase activity was found in both the female venom and the larval secretions of E. orientalis, whereas hyaluronidase was specific to the female venom.