褪黑激素及其对动物生殖影响的研究进展

褪黑激素是由松果腺分泌的一种激素,在动物的生殖、生物钟、免疫、抗自由基等方面都有重要影响。简要综述了褪黑激素的主要理化性质及其生物学功能、褪黑激素受体,并总结了近年来褪黑激素对动物生殖影响的研究进展。     

山羊体外受精胚性别鉴定不同取样方法的研究

为了不断完善山羊早期胚胎性别鉴定技术,实现奶山羊雌性胚胎的体外生产与商业化,本研究对胚胎性别鉴定的两种采样方法进行比较。结果表明,两种取样方法性别鉴定结果的准确性没有差异,桑椹胚经打孔法采样后胚胎妊娠率(36．84％)明显高于切割法(31．25％),囊胚经切割法采样后胚胎妊娠率(31．58％)明显高于打孔法(23．53％),综合比较,胚胎性别鉴定应以打孔法采集早期桑椹胚为宜。     

笼养大猩猩行为研究中瞬时扫描最适取样时间间隔的确定

2009年9～12月以4只大猩猩(Gorilla gorilla)为研究对象,应用瞬时扫描取样法观察记录其活动行为,建立不同取样间隔与数据准确性和数据独立性的线性回归方程,计算变量系数和常数项的95%置信区间,进而确定瞬时扫描法的最适取样间隔。研究结果表明,大猩猩活动主要集中于上午10:00～11:00时和下午14:00～15:00时(χ2=19.110,df=4,P=0.001),不同大猩猩个体间活动行为存在显著差异(Kruskal Wallis Test,χ2=11.229,df=3,P=0.011)。随着取样间隔的增大,间隔取样与连续取样数据的相关系数呈下降趋势,满足数据准确性需求的最适取样间隔为3～13 min,随取样间隔的增大,数据独立可能性逐渐升高,其中满足数据独立性需求的最适取样间隔为2～8 min。综合考虑以上两种因素,确定针对大猩猩活动行为的瞬时扫描取样的最适间隔为3～8 min。     

注射液不溶性微粒检查取样方法的探讨

在工作中,我们经常要对注射液的不溶性微粒进行检查,在对塑料瓶包装的注射液检查时,由于其包装的特点,对其取样不如玻璃瓶包装便捷,为探讨最佳取样方法,本人尝试用两种方法取样：（1）剪刀剪瓶口取样法：用剪刀剪开瓶口,荡洗瓶口后,将供试品倒入取样杯中检验;（2）注射器取样法：用清洗干净的注射器抽取供试品至取样杯中检验。现将两种方法的实验结果比较如下。     

农田节肢动物不同取样方法的综合比较

农田节肢动物多样性具有病虫害控制、传粉等价值, 选择一种或多种适宜、准确且高效的取样方法和指示类群来衡量农田节肢动物多样性是一项基础性工作。本文通过地表陷阱法、挂盆陷阱法、扫网法、目测计数法和吸虫器法在有机管理和常规管理农田区的不同农业生境类型中取样, 比较不同方法对不同生物类群的捕获效率、经济成本、响应敏感性等。研究发现在捕获效率方面, 地陷法和挂盆法最高, 其次是扫网法, 而吸虫器法和目测计数法较差。挂盆法对步甲、蜘蛛、蜂类和瓢虫类群的捕获效率较佳。陷阱法主要适用于蜘蛛和步甲的取样, 扫网法也可用于蜘蛛和瓢虫的取样。在经济成本方面, 地陷法的成本最低, 扫网法的总成本最高。每种取样方法下仅有个别类群个体数量具有较好的响应敏感性, 如地陷法的蜘蛛目个体数和步甲科个体数、挂盆法的总个体数、蜂类个体数和瓢虫科个体数、扫网法的直翅目个体数和半翅目个体数等。在此基础上, 综合类群经济价值, 操作难易, 类群鉴定难度, 被动取样程度, 是否受取样人影响等比较发现: 地陷法对步甲和蜘蛛的取样的综合效果最佳, 而不同取样方法下多种类群的组合能更好地监测和评价农田节肢动物多样性的整体情况。地陷法捕获步甲或/和蜘蛛以及挂盆法调查蜂类的组合是基于本研究得出的调查农田节肢动物多样性的最佳组合。     

大豆田间节肢动物群落调查取样方法的比较研究

[目的]为明确不同取样方法对分析农田节肢动物群落结构特征的影响.[方法]以大豆田间节肢动物群落为对象,采用网捕(WB)、吸虫机(XC)、定点定株(DD)、黄盘(HP)诱集和陷阱杯(XJ)诱集5种取样方法进行大豆田间节肢动物群落调查,并通过比较不同取样方法所得样本进行节肢动物群落结构特征分析结果的差异性,明确不同取样方法的优劣与可替代性.[结果]WB法采集到的类群最多,且与XC法无显著差异,DD法采集到的类群最少.从采集各目的科数、物种数和个体数看,WB法和XC法可采集大多数昆虫,DD法采集缨翅目昆虫最多,HP法采集膜翅目、双翅目、鞘翅目、跳虫目和蜱螨目种类较多,XJ法采集直翅目、膜翅目、鞘翅目和跳虫目昆虫较多.群落结构特征分析结果显示,WB法和XC机法相似性为0.75,效果相当,而其它方法之间相似性均小于0.42,相互间差异较大.在农田节肢动物群落调查时,采用WB+DD、WB+HP、WB+XJ 2种方法组合与WB+XC+DD+HP+XJ 5种方法组合获得的取样相似度均大于0.75的群落特征指标,选用WB+DD+HP、WB+DD+XJ和WB+HP+XJ 3种含有WB的方法组合与WB+XC+DD+ HP+XJ 5种方法组合获得的取样相似度均大于0.85的群落特征指标.[结论]正确选择或组合不同取样法进行群落调查可在有效提高群落生态研究的质量的同时减少调查工作量,在实际研究工作中,可根据群落对象特点和所关心的主要群落生态指标对调查取样方法进行合理选择.     

埋植褪黑激素对貂、貉促进毛皮生长效应的试验研究

本文在自然条件下,利用ＭＬＴ,人工埋植标准色淘汰成年雌貂、貉和幼龄雄貂,设做试验群。埋植期各在６月初和６月末,使用剂量为貂１０ｍｇ、貉３０ｍｇ。同时设对照群,采用同样的饲养管理手段,观察比较。其结果,不论性别和年龄,用褪黑激素处理的貂、貉、夏毛脱落和冬毛生长都比对照群快（Ｐ＜００００１）。试验群幼龄貂的体重增长速度比对照群快（Ｐ＜００００１）,食欲比对照群强。到８月２０－２５日,首先达到了标准成年貂体重,到９月２５日毛皮即成熟,比对照群提前取皮４７－５５ｄ。试验用淘汰成年雌貂和貉,毛皮成熟均比对照群早,可提前８５ｄ取皮,而且试验群皮张长度增长１５％以上,皮张等级鉴定同正常貂、貉相比,差别很小。     

中国大鲵非损害性DNA取样及提取方法的比较研究

基于DNA 分子的研究方法在物种分类及系统学、生态遗传学、保护生物学等领域中被广泛运用,但针对动物DNA取样方法的比较研究整体上较为缺乏。动物DNA取样要在对实验对象造成最小化影响和获得满足研究需要的DNA之间保持平衡,这需要不断探索取样方法的优缺点和适用性。本研究以人工繁育的水生有尾两栖动物中国大鲵（Andrias davidianus）为研究对象,比较口腔拭子、皮肤拭子、皮肤脱落物和尾静脉采血4种取样方式对DNA质量的影响。另外,基于其中皮肤拭子样品,进一步比较试剂盒法、高盐法、苯酚氯仿法和磁珠法对DNA提取效果的影响。结果表明,4种非损害性取样方法均能获取目标物种的DNA,且均未对取样对象的行为或适合度产生明显影响,但在DNA质量和浓度方面存在一定差异,其中,相对最好的为尾静脉采血,其次是口腔拭子和皮肤拭子,最差的为皮肤脱落物样品。而基于皮肤拭子样品采用4种不同DNA提取方法所获得的DNA效果整体差异不大。本研究通过以中国大鲵作为水生和非皮毛类动物的代表类群,研究并总结了不同DNA取样方法和提取方式的优缺点和注意事项,可为未来中国大鲵或其他珍稀濒危动物的非损害性取样方法及相关分子生态学研究提供借鉴。     

低温胁迫下褪黑激素对烟草悬浮细胞精氨酸脱羧酶活性的影响

研究了褪黑激素对烟草(Nicotiana tabacum)悬浮细胞在低温胁迫下精氨酸脱羧酶活性及细胞生存率的影响。发现褪黑激素可以明显提高低温胁迫下烟草悬浮细胞精氨酸脱羧酶的活性, 并明显提高细胞的生存率。表明褪黑激素可能在低温条件下通过调节植物细胞内多胺的合成而提高抵御冷害的能力。     

Effects of physiological cycles of infused melatonin on circadian rhythmicity in pigeons

Summary The role of the hormone melatonin in the circadian system of pigeons (Columba livia) was investigated. Using an automatic infusion system, melatoni at physiological levels was delivered for 10 h each day to cannulated, pinealectomized (P-X) pigeons in constant darkness. These cyclic infusions of melatonin entrained feeding rhythms in P-X pigeons while vehicle infusions were ineffective entraining agents. When the retinae of P-X pigeons were removed (E-X), feeding rhythms were abolished in constant darkness. When cyclic melatonin infusions were delivered to these birds (E-X and P-X), feeding rhythmicity was restored whereas vehicle infusions alone did not restore rhythmicity. When melatonin infusions were terminated in E-X/P-X pigeons, feeding rhythms persisted for several days but eventually decayed. Blood melatonin levels were measured in both P-X and E-X/P-X birds infused cyclically with exogenous melatonin and were found to be within the physiological range both in level and pattern. These results strongly suggest that endogenous melatonin, released by the pineal gland and the retinae, regulates the timing of feeding rhythms by entraining other oscillators in the circadian system of the pigeon.Abbreviations P-X pinealectomized - E-X bilaterally enucleated - T period of infusion cycle - LD light: dark cycle - DD constant darkness     

Chronic melatonin administration mitigates behavioral dysfunction induced by γ-irradiation

Melatonin, a ‘hormone of darkness,’ has been reported to play a role in a wide variety of physiological responses including reproduction, circadian homeostasis, sleep, retinal neuromodulation, and vasomotor responses. Our recent studies reported a prophylactic effect of exogenous melatonin against radiation-induced neurocognitive changes. However, there is no reported evidence for a mitigating effect of chronic melatonin administration against radiation-induced behavioral alterations. In the present study, C57BL/6 mice were given either whole day chronic melatonin administration (CMA) or chronic night-time melatonin administration (CNMA) by a low dose of melatonin in drinking water for a period of 2 weeks and 1 month following exposure to 6 Gy of γ-radiation. Various behavioral endpoints, such as locomotor activities, gross behavioral traits, basal anxiety level, and depressive tendencies were scored at different time points. Radiation exposure significantly impaired gross behavioral traits as observed in the open field exploratory paradigms and forced swim test. Both the CMA and CNMA significantly ameliorated the radiation-induced changes in exploratory tendencies, risk-taking behavior and gross behavior traits, such as rearing and grooming. Melatonin administration afforded anxiolytic function against radiation in terms of center exploration tendencies. The radiation-induced augmentation of immobility time in the forced swim test, indices of depression-like behavior was also inhibited by chronic melatonin administration. The results demonstrated the mitigating effect of chronic melatonin administration on radiation-induced affective disorders in mice.     

经济学思想和方法在行为生态学中的应用

从经济学观点看,动物的任何一种行为都是一种投资,同时又能获得一定的收益。进化和自然选择将趋于使动物行为的净收益增至最大,这种思想也是组建行为生态学最适模型的基础。如果为海滨蟹提供各种大小不同的贻贝任其选食的话,那么它所选食的贻贝大小往往能使它得到最大的能量净收益。为了精确地计算捕食者应当吃多少不同大小的食物,就需要建立一个最适模型。当动物领域行为的收益大于投资时,自然选择就会促进这种行为的产生和发展,而最佳领域大小则可借助于建立经济模型进行预测。将饥饿风险降至最小的原则可应用于动物的觅食决策。绒斑啄木鸟在觅食时可利用它们所收集的信息使其食物摄取率达到最大。     

Seasonal acclimation of prairie deer mice

Prairie deer mice responded to long nights by reducing their metabolic rates, core temperatures, thermal conductances and incremental metabolic responses to cold stimulus, while increasing their capacities for nonshivering thermogenesis. Some winter animals spontaneously entered daily torpor in the mornings and thereby further reduced their metabolic rates and core temperatures. Provision of exogenous melatonin (by subdermal implants) mimiced short photoperiod effects on metabolic rates and core temperatures of wild-caught, laboratory maintained animals. Provision of supplemental dietary tryptophan to laboratory animals conditioned to natural light cycles mimiced metabolic effects of long nights in summer animals, and further reduced metabolic rates of winter mice, but did not affect their core temperature levels. Newly caught, laboratory maintained deer mice responded to natural seasonal clues of shortphotoperiod and increased dietary tryptophan by reducing their resting energy requirements through both lower metabolic and lower core temperature levels. Short photoperiod and seasonal change also promoted gonadal involution, and resulted in more socially tolerant huddling by mice with reduced core temperature. Reduced 24-hour LH excretion rates were also observed in winter animals which were exposed to seasonal light cycles at warm (25°C) room temperatures. We propose that seasonal acclimatization involves pineal effects on sex hormone-influenced social behaviors and on resting metabolism. These effects serve to conserve resting energy expenditure and promote hypothermic insulation by wild prairie deer mice.     

A review of the molecular conformations of melatonin ligands at the melatonin receptor

This review examines the 1992-2000 literature on studies of the molecular conformations of melatonin ligands at the melatonin receptor. In order to investigate quantitative structure-affinity relationships between different chemical classes of melatonergic ligands binding to the melatonin GPCR, CoMFA has been applied to extended sets of compounds, to obtain 3D-QSAR agonist/antagonist models. The results of several authors have suggested that the active conformation of the C-3 aminoethyl side chain of melatonin and related compounds is in a folded form, orthogonal to the aromatic ring. Positive steric potentials were found in the C-2 region, surrounding the C-5 methoxy group and near the N -acyl group of the side chain, while substituents in positions C-6 and C-7 cause a decrease in affinity. Negative steric regions were found between indole N-1 and C-2. Receptor binding affinities have been predicted for a range of structurally diverse compounds for the sheep brain melatonin receptor considering steric, electrostatic and lipophilic fields.     

From heritability to probability

Can a heritability value tell us something about the weight of genetic versus environmental causes that have acted in the development of a particular individual? Two possible questions arise. Q1: what portion of the phenotype of X is due to its genes and what portion to its environment? Q2: what portion of X’s phenotypic deviation from the mean is a result of its genetic deviation and what portion a result of its environmental deviation? An answer to Q1 provides the full information about X’s development, while an answer to Q2 leaves out a large portion unexplained—that portion which corresponds to the phenotypic mean. Q1 is unanswerable, but I show it is nevertheless legitimate under certain quantitative genetics models. With regard to Q2, opinions in the philosophical and biological literature differ as to its legitimacy. I argue that not only is it legitimate, but in particular, under a few simplifying assumptions, it allows for a quantitative probabilistic answer: for normally distributed quantitative traits with no G-E correlation or statistical G × E interaction, we can assess the probability that X’s genes had a greater effect than its environment on its deviation from the mean population value. This probability is expressed as a function the heritability and the individual’s phenotypic value; we can also provide a quantitative probabilistic answer to Q2 for an arbitrary individual where the probability is a function only of heritability.     

Development of an optimal sampling protocol for millipedes (Diplopoda)

This study determined a millipede sampling protocol that was efficient, replicable, and thorough, by testing commonly used methods (pitfall trapping, hand collection, and leaf litter collection with Berlese extraction) at sites where the fauna had been intensively sampled, so that the results of different sampling protocols (‘experimental sampling’) could be compared to the previously known fauna of each site (determined by ‘baseline sampling’). Two methods of collecting leaf litter were compared. One method allowed the collector to choose the locations from which to sample leaf litter, while the second method used randomly generated locations. Experimental sampling took place at both an upland site (Swallow Cliff Woods, Cook Co, IL) and a wetland site (Cedarburg Bog, Ozaukee Co, WI) where reliable baseline data was available. The optimal protocol for millipedes was found to consist of a combination of the hand collection and the a priori litter methods. In studies where there are constraints on time or resources devoted to sampling or processing, this protocol can be reduced to the single most effective method, hand collection. Overall, the a priori litter collection method was more effective than the random litter collection method.     

The epidermal growth factor receptor and its ligands in female reproduction: insights from rodent models

Recent studies employing molecular, cellular, and whole organism approaches have identified the epidermal growth factor receptor (EGFR) and its ligands as key players in female reproductive functions. Gene expression studies demonstrated that the members of this family are expressed in a timely and spatially coordinated manner in different reproductive tissues. Manipulation of the EGFR system in rodent models by pharmacological or surgical means as well as elimination or overexpression of specific components of the EGFR system in genetically modified mice resulted in aberrant reproductive phenotypes, highlighting the physiological relevance of these molecules. This article summarizes the experimental evidence derived from rodent models, leading to our current understanding of the roles of the EGFR system in key steps of reproduction, such as ovulation, fertilization, embryo implantation, and the attainment of sexual maturity.