棘头梅童鱼的细胞遗传学特征和X1X1X2X2/X1X2Y性染色体系统     

张寿康  郑娇  张静  王志勇  王艺磊  蔡明夷 《海洋学报(英文版)》2018,37(4):34-39

我们通过荧光染色、自身基因组原位杂交（Self-GISH）和多色荧光原位杂交（FISH）,首次研究了棘头梅童鱼（Richardson,1844）的核型特征。雌性核型有24对端部着丝粒染色体（2n=48a,NF=48）,而雄性核型包含22对端部着丝粒染色体,2条端部着丝粒染色体单体和1条中间着丝粒染色体（2n=1m+46a,NF=48）。雌性和雄性核型之间的差异表明,棘头梅童鱼的性染色体系统为X₁X₁X₂X₂/X₁X₂Y型,其中Y为雄性中特有的中间着丝粒染色体。三色FISH结果显示,5S rDNA和18S rDNA位点定位在最大的端着丝粒染色体（X₁）以及Y染色体的短臂;X₁染色体上有一个特异的臂间端粒信号（ITS）,与5S rDNA位点部分重叠。Self-GISH结果显示,在推定的性染色体DNA重复序列聚集。根据实验结果我们提出关于棘头梅童鱼Y染色体起源的假说：Y染色体起源于祖先核型（2n=48a）中的两条端部着丝染色体融合,并且在此过程中伴随着片段缺失。本研究首次在石首鱼科中描述了异形的性染色体,将为其他石首鱼的性染色体研究提供线索。  相似文献   

企鹅珍珠贝生殖细胞的发生     

徐宗芹  王梅芳  梁飞龙  余祥勇 《广东海洋大学学报》2009,29(6):32-35

对不同发育阶段的企鹅珍珠贝[Ptedapenguin(Rding)]的性腺结构、生殖细胞结构与分布进行组织学观察,描述精/卵子发生过程中各级精/卵细胞的特征。结果表明:根据雌性生殖细胞形态和卵黄的变化特点,卵子发生经历卵原细胞、无卵黄初级卵母细胞、卵黄形成期卵母细胞及成熟卵子阶段;依据雄性生殖细胞大小和细胞核形态变化,精子发生经历精原细胞、初级精母细胞、次级精母细胞、精子细胞和精子阶段,其中精原细胞存在形态上有差异的A型和B型两种类型。此外还观察到企鹅珍珠贝的性别转化现象。  相似文献   

Reproductive biology of yellowfin tuna T. albacares in the west-central Indian Ocean     

Guoping Zhu  Liuxiong Xu  Yingqi Zhou  Liming Song 《中国海洋大学学报(英文版)》2008,7(3):327-332

Survey of yellowfin tuna in the west-central Indian Ocean was conducted on board of Chinese longliners during 2003, 2004 and 2005, which is a part of Chinese Tuna Fishery Scientific Observer Program (CTFSOP). The reproductive biology has been investigated. A total of 1 023 samples are collected including 417 ovaries and 606 testes. Spawning activities of yellowfin tuna have been studied for both male and female from January to June. The data showed that the average monthly sex ratio is 0.59, and the minimum length at sexual maturity is 101 cm for female and 110 cm for male respectively. Length at 50% sexual maturity is estimated at 113.77 cm for female and 120.20 cm for male, whereas maturation rate is 0.066 cm⁻¹ for female and 0.091 cm⁻¹ for male. Sex ratio by length class indicates that the proportion of male is higher than female’s along with size increasing; for instance, in the group of the body length longer than 145 cm, some females have their body length from 145 to 160 cm and males have their body length at 160 cm and even longer. Statistically, yellowfin tuna has a significant seasonal reproduction.  相似文献   

Molecular cloning, characterization and expression analysis of Sox9a and Foxl2 genes in half-smooth tongue sole (Cynoglossussemilaevis)     

DONG Xiaoli  CHEN Songlin  JI Xiangshan  SHAO Changwei 《海洋学报(英文版)》2011,30(1):68-77

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New Material of Feilongus (Reptilia: Pterosauria) from the Lower Cretaceous Jiufotang Formation of Western Liaoning     

WANG Xuri  SHEN Caizhi  GAO Chunling  JIN Kemo 《《地质学报》英文版》2014,88(1):13-17

Based on a new nearly naturally preserved skull and four cervical vertebrae of the pterosaur Feilongus sp. from the lower Cretaceous Jiufotang Formation of Beipiao, western Liaoning province, northeastern China, the diagnosis of Feilongus is amended. The revised diagnosis notes long, curved, needle-shaped teeth that are confined to the jaw far anterior to the nasoantorbital fenestra; posterior teeth that are slightly smaller than the anterior teeth; cervical vertebrae elongated with a ratio of length to width greater than 5; tooth number of about 78; and two cranial sagittal crests.  相似文献   

The reproductive style of Diplodus capensis (Sparidae) in southern Angola: rudimentary hermaphroditism or partial protandry?     

《African Journal of Marine Science》2013,35(2):321-326

The reproductive style of Diplodus capensis was examined in an unexploited coastal area in southern Angola. The mean length of females was significantly greater than that of males and, although not significant, females dominated the older age classes. The overall sex ratio was 1 male:4.7 females and female dominance increased with size. Histological analysis of gonads revealed that this species is a rudimentary hermaphrodite, with individuals possessing a non-functional bipotential ovotes-tis in the juvenile phase. Histological examination of the gonads of four macroscopically staged ‘intersex’ individuals suggested that they were functional males with a persistent ovarian portion in their gonads from the juvenile ovotestis. The heavily female-biased sex ratio and female dominance in the larger length classes are thought to be an alternative to sex change that is more resilient to exploitation when compared with the protandrous strategy displayed by the South African population of D. capensis.  相似文献   

浙江东阳晚白垩世早期翼龙足迹(英文)     

CHEN Rong-jun  Lü Jun-chang  Zhu Yang-xiao  AZUMA Yoichi  ZHENG Wen-jie  JIN Xing-sheng  NODA Yoshikazu  SHIBATA Masateru 《地质通报》2013,32(5):693-698

根据中国浙江东阳上白垩统金华组发现的4个翼龙足迹,建立翼龙一新的遗迹种:东阳翼龙足迹。它具有以下特征:手迹的第Ⅱ和第Ⅲ指夹角为29°,第Ⅰ指和第Ⅱ指的夹角为52°;足迹的长与宽的比率为0.17,除了翼龙足迹外,在同一层位中还发现有蜥脚类、鸟脚类、兽脚类、帯蹼和不具蹼的鸟类足迹。这些足迹化石的发现,为研究该地区的古生态环境及以后动物的骨骼化石,尤其是翼龙骨骼化石提供了重要依据。  相似文献   

A spatial approach to select pilot counties for programs to correct the biased sex ratio at birth in Shandong province,China     

Kun Zhang  Shawn William Laffan  Songlin Zhang 《International journal of geographical information science》2013,27(3):403-416

The highly skewed sex ratio at birth (SRB) in China has stimulated numerous studies. However, the geographic distribution of SRB is seldom investigated, particularly at the county level. The need for an understanding at this level has increased since the Chinese government initiated its ‘Care for Girls’ campaign to improve the survival rate of females. This campaign has been initiated in a set of pilot counties. In this article we assess the effectiveness of the set of pilot counties in Shandong province and propose two alternate configurations. To do this, we first assess the spatial distribution of the SRB values by county in Shandong, expressed as a z-score (zSRB) after correcting for the biologically expected SRB value and population size of zero-aged children. A local Moran's I_i analysis of the zSRB values indicates a significant high–high cluster in the southwest of the province. The I_i , zSRB and female deficit (the difference of the observed from biologically expected number of zero-aged females) were then used to define two alternate configurations for the pilot counties. A comparison of the current and alternate configurations against a Monte Carlo randomisation analysis shows that the current configuration is significantly different from a random selection (p < 0.05) for the two criteria of maximising the aggregate female deficit and maximising the zSRB. Although this is a good result, both alternate configurations were more significant (p < 0.001), and therefore represent potentially better configurations for the campaign given the criteria used. The spatial analysis approach developed here could be used to improve the effectiveness of the Care-for-Girls campaign in Shandong province, and elsewhere in China.  相似文献   

The Migration of Partnered Gays and Lesbians between 1995 and 2000     

Thomas J. Cooke  Melanie Rapino 《The Professional geographer》2007,59(3):285-297

This research investigates the interregional migration of partnered gays and lesbians between 1995 and 2000 as the first attempt at understanding the determinants of gay and lesbian migration using data from the Public Use Microdata Sample of the 2000 U.S. Census. Briefly, the findings are as follows. Both partnered gays and lesbians are regionally distributed throughout the United States consistent with the geographical distribution of the entire U.S. population. However, the shifting location of the partnered gay and lesbian population between 1995 and 2000 demonstrates significant variability. The general conclusion to be reached from models of the net migration of the partnered gay and lesbian population in that period is as follows: Partnered gay migration is directed toward moderate‐sized urban regions rich in natural amenities without regard for tolerance toward gay lifestyles or the absolute or relative size of the partnered gay community. Partnered lesbian migration is focused on less‐populous regions with a large, existing, partnered lesbian population. The role of natural amenities, the tolerance for lesbian lifestyles, and population density are not significant in determining partnered lesbian migration. The only trait partnered gay and lesbian migrations have in common is in their move toward less populous regions.  相似文献   

紫菜减数分裂的研究现状及展望     

王娟  戴继勋  张义听  杨堃峰 《中国海洋大学学报(自然科学版)》2006,36(3):377-380

紫菜的减数分裂是紫菜育种和遗传研究的重要理论基础。文中综述了紫菜减数分裂的研究现状,对前人在减数分裂的细胞形态学观察、色素突变体和性别决定的遗传分析研究进行了系统的分析,指出了研究中存在的问题。并对减数分裂这一遗传现象进行了重新认识,提出紫菜减数分裂可能发生在壳孢子形成至壳孢子萌发的第一次细胞分裂时期。根据对文献资料的分析及初步研究,认为紫菜减数分裂的争论问题,还未得到满意的解决,因此仍有重新认识和深入研究的必要。  相似文献