太阳系中,以木卫二和土卫二为代表的冰天体具有突出的生命潜力,可能在21世纪解答人类关于地外生命的终极问题.Exo-AUV能在冰壳中、冰水交界和海底等潜力区域执行生命探测任务,被NASA等机构寄予厚望.然而,具体在哪、基于何方法、开发何种...太阳系中,以木卫二和土卫二为代表的冰天体具有突出的生命潜力,可能在21世纪解答人类关于地外生命的终极问题.Exo-AUV能在冰壳中、冰水交界和海底等潜力区域执行生命探测任务,被NASA等机构寄予厚望.然而,具体在哪、基于何方法、开发何种Exo-AUV和技术、达到什么目标,是未来冰天体生命探测任务重要议题.本研究以木卫二为假想目标,探讨了冰天体生命探测任务的科学目标、可探测对象、潜力区域和生源性分析,提出了一种基于Exo-AUV的冰天体生命探测方法;解析了Exo-AUV在不同作业场景下的关键条件,提出了艇体、载荷和自主三方面基本技术要求;介绍了Exo-AUV的研究背景、研究现状和存在问题,提出了一套Exo-AUV概念开发技术路线和一种多Exo-AUV系统作业概念(ConOps for MEAS).该系统将帮助行星科学家和天体生物学家探索冰天体、寻找强生源信号,甚至活体生命和前生命化学系统.展开更多
According to conventional theory, little genomic changes should occur in homozygous and stable amphiploids of the grass family, particularly those involving polyploid wheat as a parent. In the present study, however, ...According to conventional theory, little genomic changes should occur in homozygous and stable amphiploids of the grass family, particularly those involving polyploid wheat as a parent. In the present study, however, extensive genomic changes were detected in two octoploid partial amphiploids of common wheat (Triticum aestivum L.)_wheatgrass (Agropyron intermedium (Host) P.B.=Elytrigia intermedia (Host) Nevski=Thinopyrum intermedium (Host) Barkworth and Dewey), namely Zhong 3 and Zhong 5, by RFLP analysis using 10 low_copy, wheat chromosome_specific sequences and 33 representative homoeologous group_specific sequences as probes. Genomic changes involved loss of wheat hybridization fragment(s) and/or acquisition of new fragment(s). Uniformity of the RFLP patterns among 5 individual plants taken respectively from Zhong 3 and Zhong 5 in two successive generations, suggested that genomic changes probably had occurred in the early few generations after octoploid amphiploid formation, and remained essentially static thereafter. The highly similar RFLP patterns between Zhong 3 and Zhong 5, which had identical genomic constitution but differed from each other due to involvement of different wheat varieties as parents imply that genomic changes were probably not at random. Possible causes for the extensive and rapid genomic changes in the newly formed plant amphiploids, as well as their implications for polyploid genome evolution and breeding application are discussed.展开更多
文摘太阳系中,以木卫二和土卫二为代表的冰天体具有突出的生命潜力,可能在21世纪解答人类关于地外生命的终极问题.Exo-AUV能在冰壳中、冰水交界和海底等潜力区域执行生命探测任务,被NASA等机构寄予厚望.然而,具体在哪、基于何方法、开发何种Exo-AUV和技术、达到什么目标,是未来冰天体生命探测任务重要议题.本研究以木卫二为假想目标,探讨了冰天体生命探测任务的科学目标、可探测对象、潜力区域和生源性分析,提出了一种基于Exo-AUV的冰天体生命探测方法;解析了Exo-AUV在不同作业场景下的关键条件,提出了艇体、载荷和自主三方面基本技术要求;介绍了Exo-AUV的研究背景、研究现状和存在问题,提出了一套Exo-AUV概念开发技术路线和一种多Exo-AUV系统作业概念(ConOps for MEAS).该系统将帮助行星科学家和天体生物学家探索冰天体、寻找强生源信号,甚至活体生命和前生命化学系统.
文摘According to conventional theory, little genomic changes should occur in homozygous and stable amphiploids of the grass family, particularly those involving polyploid wheat as a parent. In the present study, however, extensive genomic changes were detected in two octoploid partial amphiploids of common wheat (Triticum aestivum L.)_wheatgrass (Agropyron intermedium (Host) P.B.=Elytrigia intermedia (Host) Nevski=Thinopyrum intermedium (Host) Barkworth and Dewey), namely Zhong 3 and Zhong 5, by RFLP analysis using 10 low_copy, wheat chromosome_specific sequences and 33 representative homoeologous group_specific sequences as probes. Genomic changes involved loss of wheat hybridization fragment(s) and/or acquisition of new fragment(s). Uniformity of the RFLP patterns among 5 individual plants taken respectively from Zhong 3 and Zhong 5 in two successive generations, suggested that genomic changes probably had occurred in the early few generations after octoploid amphiploid formation, and remained essentially static thereafter. The highly similar RFLP patterns between Zhong 3 and Zhong 5, which had identical genomic constitution but differed from each other due to involvement of different wheat varieties as parents imply that genomic changes were probably not at random. Possible causes for the extensive and rapid genomic changes in the newly formed plant amphiploids, as well as their implications for polyploid genome evolution and breeding application are discussed.
