Direct evidence of multiple paternities in natural population of viviparous Japanese surfperch by allelic markers of microsatellite DNA loci

This study was performed to obtain information on the occurrence of multiple paternities in three species of viviparous Japanese surfperch using allelic markers of microsatellite DNA loci. Direct evidence for multiple fertilizations was established by reconstructing paternal genotypes from the progeny of gravid females. Multiple paternities were ascertained in five of 10 broods of Ditrema temmincki and in three of nine broods of Neoditrema ransonneti, but not in Ditrema viride. The number of patrilines detected in the progeny of D. temmincki and N. ransonneti females were two or three, respectively, as determined by the GERUD v2.0 algorithm for reconstructing parental genotypes from half-sib progeny arrays.     

Impaired larval development in broods of eelpout (<Emphasis Type="Italic">Zoarces viviparus</Emphasis>) in Danish coastal waters

Eelpouts (Zoarces viviparus), a viviparous fish, were sampled in Danish coastal waters during October and November 2001 and 2002, in ten different areas, which are receiving effluents from cities and industry to more or minor degree. The presence of gross abnormalities in eelpout broods has been suggested to be a useful biomarker of the impact of hazardous substances on fish reproduction in the marine environment as chronic exposure to various substances has the potential to induce severe developmental defects in fish embryos and larvae. Relatively high frequencies of female eelpouts (20–53) with elevated levels (>5) of larvae with developmental defects in the broods were found in four shallow fjords with effluents from larger cities and industry compared to areas. Deformations like spiral or bend shapes of the spinal axis, cranio-facial defects, eye lesions or loss of eyes were the dominating types. In some ofthe areas with the highest incidences of developmental defects, the adults had significantly enlarged livers, which may also be a possible effect caused by contaminant exposure. In two of the areas, relatively high frequencies of the broods contained larvae, which had died late but without any visible developmental defects. These two areas were affected by severe oxygen depletion prior to sampling time suggesting that examination of broods in the eelpout may include not only impact of hazardous substances but also effect of eutrophication-related problems on fish reproduction in the marine environment.     

Size‐based sexual dimorphism of nitrogen excretion in livebearing fishes

Nitrogen (N) and phosphorus (P) are important limiting or co‐limiting nutrients in many aquatic ecosystems. Consumers such as fishes can significantly impact the balance and redistribution of these nutrients through consumer‐driven nutrient recycling. Intraspecific variation in nutrient excretion rates can therefore have significant ecosystem impacts. Among individuals of sexually dimorphic consumers, variation in population size structure and sex ratio could potentially have impacts of similar magnitude. We tested for the effects of body size and sex on consumer‐driven nutrient recycling by measuring N and P excretion rates from eight species of poeciliid fishes. We found a strong positive effect of size on N excretion rates, as has been previously described among species. However, we found no effect of size on P excretion rates, nor did we find any difference in N or P excretion rates between sexes. Our work provides a preliminary analysis of how sexual dimorphism can lead to disparate nutrient excretion rates within consumer populations. These results indicate that variation in population sex ratios of sexually dimorphic consumers could have impacts at the ecosystem scale.     

落地生根胎生苗发育解剖学研究

以室内栽培的落地生根(Bryophyllum daigremontianum(Ham.et Perr.)A.Berg)为材料,利用常规石蜡切片法,对其胎生苗发育过程进行了解剖学研究。结果表明,落地生根的胎生苗是一种特殊的胎生苗类型,由叶的边缘粗齿的凹陷处伸长并向外反转成舌状体,并在舌状体上表面形成胎生苗原基;胎生苗发育,由胎生苗原基上端分化产生不定芽,不定芽发育后期,在胎生苗原基基部产生一至数枚不定根原基,胎生苗脱落前,不定根一般不伸出体外。胎生苗发育成熟后由离层处自行脱落、传播,不定根迅速伸长,扎入土中,很快形成独立植株。     

Studies on triploid viviparous onions and their origin

The cultivation of the triploid viviparous onion is reported from Tibet, Kashmir, Jammu, Croatia, Germany, The Netherlands, France, Guadeloupe, and Canada. Because of certain resemblance to the diploid top onion, Allium x proliferum, it was assumed that the parents of triploids might be also A. cepa and A. fistulosum. Accessions of A. altaicum, A. cepa, A. fistulosum, A. galanthum, A. oschaninii, A. x proliferum, A. pskemense, A. roylei, A. schoenoprasum, and A. vavilovii were investigated by isozyme analysis. The results confirmed only one species of sect. Cepa, either A. cepa, A. oschaninii or A. vavilovii, as parent of the triploid onions. A. fistulosum was excluded from the ancestry. The second parent remains still unknown. Two rare species of sect. Cepa s.l., A. farctum from Pakistan and Afghanistan and A. rhabdotum from Bhutan, were not studied. They could have been involved in the evolution of the triploids and should be analysed in this respect.     

一个新的玉米Vp15基因等位突变体的遗传分析与分子鉴定

在玉米繁种过程中发现一个玉米穗发芽突变体(viviparous), 命名为vp-like4。经过连续多代自交发现该突变体性状能稳定遗传, 并且表现为隐性单基因控制。以vp-like4与自交系Mo17杂交构建F₂遗传定位群体, 利用BSR-Seq方法, 将目的基因定位于玉米第5染色体173.8~175.6 Mb之间。通过基因组序列信息分析发现, 在此定位区间内存在一个已报道的Vp15基因。Vp15基因编码钼喋呤合酶小亚基, 参与类胡萝卜素裂解为ABA的过程。利用2个独立的vp15突变体vp15-umu1和vp15-DR1126的杂合体, 分别与vp-like4突变体杂合体做杂交进行等位测验, 发现杂交后代中正常籽粒与穗发芽籽粒比例符合3∶1分离比。基因组序列分析发现vp-like4突变体中Vp15基因在第2外显子末端及3°非翻译区有60个碱基的缺失, 与所报道的vp15突变体vp15-umu1、vp15-DR1126均在第2个外显子有Mutator转座子插入的突变方式不同。进一步通过RT-PCR检测发现, vp-like4突变体中Vp15基因的表达量显著降低。以上实验证据表明, vp-like4是一个新的Vp15基因等位突变体。     

有翅孤雌型桃蚜口器感受器的扫描电镜观察

采用扫描电镜技术对有翅孤雌型桃蚜口器上的感受器进行了系统的观察与分析。结果表明:感受器大都集中于喙管表面,主要有毛形感受器、刺形感受器及锥形感受器三种类型。其中,毛形感受器和刺形感受器分布于整个喙管的表面;锥形感受器只存在于喙管的顶端,共16根且以口沟为中心对称分布。笔者分别描述了三种感受器的外部形态特征,并对其可能的功能进行了初步探讨。     

Review. Levels of Recirculating Reproductively-related Steroid Hormones in Female Elasmobranchs. Implications for Reproduction in a Captive Environment

Chondrichthyans are a diverse group in terms of reproductive mode, which range from extended oviparity to placental viviparity. Although the reproductive biology of several species has been investigated, the reproductive physiology of only a few species has been reported. Only recently have the physiological factors of reproduction in cartilaginous fishes received attention. The information gained on reproductive cycles (both gonadal and uterine) has shown some similarities as well as differences between species. The serum levels of androgens, oestrogens, and progestins have been examined in several elasmobranch species and it has been shown that they are important in regulating key events in reproduction. The endocrine control of reproduction in elasmobranchs is more similar in many ways to higher vertebrates such as mammals than to teleosts. In general, the role of progesterone becomes more important than that of oestrogen in the transition from oviparity to viviparity. In addition, the roles of peptide hormones such as relaxin and the neurohypophysial hormones become increasingly important in viviparous species as in higher vertebrates. It is vital to understand the environmental and hormonal control of reproduction in elasmobranchs if more success is to be achieved in their reproduction in captivity. Knowledge gained from studies of the endocrine regulation of the reproductive cycle can be used to enhance the reproductive success of captive sharks, skates, and rays. This revised version was published online in August 2006 with corrections to the Cover Date.     

木榄胎生繁殖体产量预测模型

木榄(Bruguiera gymnorrhiza)是红树科木榄属常绿乔木,生长于泛热带海岸的中潮带至高潮滩地,具有膝状呼吸根及支柱根,是我国红树林植物中分布最广的主要乔木树种之一,种子在母树上就已经萌发成苗,故称为胎生繁殖体或者胚轴(廖宝文等,2002).木榄在生态、工农业和药用方面具有较高的价值(于凌杰等,2009;郑燕影等,2008).近几年,国内学者在生理生态、化学组成方面对木榄进行了较多的研究(蔡由生等,2011;叶波平等,2010;郭庆水等,2010;李昉等,2010;陶毅明等,2009;姚贻强等,2009),但对木榄胎生繁殖体的产量预测研究甚少.