Artificially induced tetraploid Pacific oyster, Crassostrea gigas Thunberg, produces more aneuploid gametes than nor- mal diploid one, although they showed a comparable fecundity to diploidy. The meiotic chromosome co...Artificially induced tetraploid Pacific oyster, Crassostrea gigas Thunberg, produces more aneuploid gametes than nor- mal diploid one, although they showed a comparable fecundity to diploidy. The meiotic chromosome configuration of 3 tetraploid and 1 tetraploid/triploid mosaic males were analyzed through direct chromosome observation. A majority of metaphase I spermato- cytes contained both bivalents and quadrivalents. The chromosome configuration of these males was characterized by preferential formation of bivalents to quadrivalents. Bivalents appeared in all spermatocytes and consisted of 86% of all chromosome aggregates. In comparison, quadrivalents occurred in 91% spermatocytes and consisted of only 12.6% of all chromosome aggregates. The mean bivalent frequency per spermatocyte varied between 14.4 and 17.2; while that of quadrivalents varied between 2.2 and 2.7. Most quadrivalents were tandemly chained （58%） or circled （39%）. The total number of chromosome aggregates per spermatocyte ranged from 13 to 20 with an average of 17.6; while 18 （16 bivalents and 2 quadrivalents） was the most frequent. Univalents and trivalents appeared in very low frequency. Aneuploid （hypotetraploid） spermatocytes were observed in a low frequency. The chromosome con- figuration of in the mosaic individual was similar to that of tetraploid individuals. The percentage of triploid spermatocytes （2%） of the mosaic individual was significantly lower （2＂2 =30, P〈 0.01） than that of triploid cells （46%） in its somatic tissue.展开更多
Since the rise of the Internet in China,China’s local governments have actively used Internet technology to facilitate public administration and public services.What impact,then,have different types of social media h...Since the rise of the Internet in China,China’s local governments have actively used Internet technology to facilitate public administration and public services.What impact,then,have different types of social media had on local governance?This paper,based on years of investigation of J Town and L Sub-district in Shanghai(2012-2018),finds that Internet technology has profoundly transformed the grassroots power structure.Before the rise of the Internet,the grassroots power structure included local government,activists and the masses;in the age of Weibo and home owners forums,grassroots opinion leaders rose,becoming an impressive social force that local government could not afford to ignore;in the age of WeChat,however,the influence of grassroots opinion leaders declined,as local government can interact directly with the masses through WeChat public accounts and WeChat group chats,with the network technology becoming a tool for micromanagement.These three stages correspond to three types of government characterized by limited mobilization,consultation,and user-friendliness,respectively.展开更多
文摘Artificially induced tetraploid Pacific oyster, Crassostrea gigas Thunberg, produces more aneuploid gametes than nor- mal diploid one, although they showed a comparable fecundity to diploidy. The meiotic chromosome configuration of 3 tetraploid and 1 tetraploid/triploid mosaic males were analyzed through direct chromosome observation. A majority of metaphase I spermato- cytes contained both bivalents and quadrivalents. The chromosome configuration of these males was characterized by preferential formation of bivalents to quadrivalents. Bivalents appeared in all spermatocytes and consisted of 86% of all chromosome aggregates. In comparison, quadrivalents occurred in 91% spermatocytes and consisted of only 12.6% of all chromosome aggregates. The mean bivalent frequency per spermatocyte varied between 14.4 and 17.2; while that of quadrivalents varied between 2.2 and 2.7. Most quadrivalents were tandemly chained （58%） or circled （39%）. The total number of chromosome aggregates per spermatocyte ranged from 13 to 20 with an average of 17.6; while 18 （16 bivalents and 2 quadrivalents） was the most frequent. Univalents and trivalents appeared in very low frequency. Aneuploid （hypotetraploid） spermatocytes were observed in a low frequency. The chromosome con- figuration of in the mosaic individual was similar to that of tetraploid individuals. The percentage of triploid spermatocytes （2%） of the mosaic individual was significantly lower （2＂2 =30, P〈 0.01） than that of triploid cells （46%） in its somatic tissue.
基金supported by a grant from the fourth set of the Elite Youth Talent Subprogram of the National Ten Thousand Talents Program
文摘Since the rise of the Internet in China,China’s local governments have actively used Internet technology to facilitate public administration and public services.What impact,then,have different types of social media had on local governance?This paper,based on years of investigation of J Town and L Sub-district in Shanghai(2012-2018),finds that Internet technology has profoundly transformed the grassroots power structure.Before the rise of the Internet,the grassroots power structure included local government,activists and the masses;in the age of Weibo and home owners forums,grassroots opinion leaders rose,becoming an impressive social force that local government could not afford to ignore;in the age of WeChat,however,the influence of grassroots opinion leaders declined,as local government can interact directly with the masses through WeChat public accounts and WeChat group chats,with the network technology becoming a tool for micromanagement.These three stages correspond to three types of government characterized by limited mobilization,consultation,and user-friendliness,respectively.
