The early Silurian Chongqing Lagerstätte(middle Telychian)yields exceptionally preserved articulated jawless and jawed fishes.Here,we describe a new eugaleaspiform(Galeaspida,jawless stem-Gnathostomata),Miaojiaas...The early Silurian Chongqing Lagerstätte(middle Telychian)yields exceptionally preserved articulated jawless and jawed fishes.Here,we describe a new eugaleaspiform(Galeaspida,jawless stem-Gnathostomata),Miaojiaaspis dichotomus gen.et sp.nov.,from the Chongqing Lagerstätte in Xiushan,Chongqing,China.The new form resembles Tujiaaspis vividus in the short medial dorsal canal,and the presence of the branching ends of the lateral transverse canal.They differ in that T.vividus has highly developed subordinate branches of the sensory canals that form a reticulate sensory canal system,and the median dorsal opening is more elongated.Our phylogenetic analysis recovers M.dichotomus and T.vividus as a monophyletic clade(Tujiaaspidae fam.nov.),which is supported by two synapomorphies:the short medial dorsal canal,and the branching ends of the lateral transverse canal.Tujiaaspidae forms a trichotomy with Shuyuidae and a clade comprising Anjiaspis,Sinogaleaspidae,Yongdongaspidae,and the‘eugaleaspid cluster’.The sensory canal patterns in galeaspids are compared to show the transformation sequence of the sensory canal system in Eugaleaspiformes.展开更多
随着工业化发展,环境污染物的种类和数量不断增加。环境污染物广泛存在于空气、食品和生活用品等传播介质中,妊娠期接触环境污染物不仅影响孕妇健康,还可能对分娩结果及胎儿的发育产生不利影响。胎盘作为母体和胎儿之间的屏障,对部分环...随着工业化发展,环境污染物的种类和数量不断增加。环境污染物广泛存在于空气、食品和生活用品等传播介质中,妊娠期接触环境污染物不仅影响孕妇健康,还可能对分娩结果及胎儿的发育产生不利影响。胎盘作为母体和胎儿之间的屏障,对部分环境污染物具有选择性阻隔作用,即一些污染物被阻留于母体血液,而另一些环境污染物通过被动扩散、胎盘转运蛋白或内吞作用穿过胎盘屏障,进入胎儿脐带血中。跨胎盘转移效率(transplacental transfer efficiency,TTE)即污染物在脐带血中与在母体血液中水平的比值,常用于评估环境污染物跨越胎盘屏障的能力。TTE与污染物的相对分子质量、脂溶性、极性和结构特征等理化性质有关;母体和胎儿的健康状况、胎盘血流量、胎盘成熟度、胎盘转运蛋白和代谢酶的功能也会显著影响污染物的转移过程。本文总结了TTE的研究方法以及近年来有关环境污染物(全氟和多氟烷基物质(PFASs)、多溴二苯醚(PBDEs)、多氯联苯(PCBs)和有机氯农药(OCPs)等)的TTE研究进展,并讨论了影响TTE的主要因素。本文对环境污染物的跨胎盘转移机制研究具有指导意义,并有助于评估环境污染物对孕妇和胎儿健康风险的影响。展开更多
文摘The early Silurian Chongqing Lagerstätte(middle Telychian)yields exceptionally preserved articulated jawless and jawed fishes.Here,we describe a new eugaleaspiform(Galeaspida,jawless stem-Gnathostomata),Miaojiaaspis dichotomus gen.et sp.nov.,from the Chongqing Lagerstätte in Xiushan,Chongqing,China.The new form resembles Tujiaaspis vividus in the short medial dorsal canal,and the presence of the branching ends of the lateral transverse canal.They differ in that T.vividus has highly developed subordinate branches of the sensory canals that form a reticulate sensory canal system,and the median dorsal opening is more elongated.Our phylogenetic analysis recovers M.dichotomus and T.vividus as a monophyletic clade(Tujiaaspidae fam.nov.),which is supported by two synapomorphies:the short medial dorsal canal,and the branching ends of the lateral transverse canal.Tujiaaspidae forms a trichotomy with Shuyuidae and a clade comprising Anjiaspis,Sinogaleaspidae,Yongdongaspidae,and the‘eugaleaspid cluster’.The sensory canal patterns in galeaspids are compared to show the transformation sequence of the sensory canal system in Eugaleaspiformes.
文摘随着工业化发展,环境污染物的种类和数量不断增加。环境污染物广泛存在于空气、食品和生活用品等传播介质中,妊娠期接触环境污染物不仅影响孕妇健康,还可能对分娩结果及胎儿的发育产生不利影响。胎盘作为母体和胎儿之间的屏障,对部分环境污染物具有选择性阻隔作用,即一些污染物被阻留于母体血液,而另一些环境污染物通过被动扩散、胎盘转运蛋白或内吞作用穿过胎盘屏障,进入胎儿脐带血中。跨胎盘转移效率(transplacental transfer efficiency,TTE)即污染物在脐带血中与在母体血液中水平的比值,常用于评估环境污染物跨越胎盘屏障的能力。TTE与污染物的相对分子质量、脂溶性、极性和结构特征等理化性质有关;母体和胎儿的健康状况、胎盘血流量、胎盘成熟度、胎盘转运蛋白和代谢酶的功能也会显著影响污染物的转移过程。本文总结了TTE的研究方法以及近年来有关环境污染物(全氟和多氟烷基物质(PFASs)、多溴二苯醚(PBDEs)、多氯联苯(PCBs)和有机氯农药(OCPs)等)的TTE研究进展,并讨论了影响TTE的主要因素。本文对环境污染物的跨胎盘转移机制研究具有指导意义,并有助于评估环境污染物对孕妇和胎儿健康风险的影响。
