为探讨滩涂围垦对海滨地区景观格局带来的影响,选取1973—2013年Landsat1、4、5、7、8影像数据,利用GIS(Geographic Information System)、RS(Remote Sensing)和景观指数计算方法,对盐城国家级自然保护区(川东港-新洋港段)已围垦区和未...为探讨滩涂围垦对海滨地区景观格局带来的影响,选取1973—2013年Landsat1、4、5、7、8影像数据,利用GIS(Geographic Information System)、RS(Remote Sensing)和景观指数计算方法,对盐城国家级自然保护区(川东港-新洋港段)已围垦区和未围垦区,以及典型垦区(海丰、海北和金丰垦区)围垦前后景观变化情况进行对比分析。1973—2013年研究区围垦特征如下:以10a为间隔,围垦区域平行于海岸线呈条带状向海推进,且条带逐渐变窄;围垦难度逐渐加大,总体上围垦强度呈减小趋势,过程上围垦面积呈升降交替状态;围垦后垦区利用方式各异,主要以种植业和养殖业为主。受围垦影响该区景观格局变化如下:1973—2013年,未围区(Ⅰ区)自然植被面积增加4762 hm2,斑块形状日益复杂、自然,分维数由1.10上升到1.15,景观破碎化水平较低,在0.17—0.21之间,多样性指数由1.11上升至1.52;已围区(Ⅱ、Ⅲ、Ⅳ区)自然植被面积不断减少,分别减少了9873、13788 hm2和6890 hm2,斑块形状更加简单、规则,分维数分别下降了0.03、0.03和0.02,破碎化程度分别上升了0.21、0.23和0.17,多样性均先升后降,升幅约0.8,降幅约0.5。海北、海丰、金丰垦区自然景观不断向人工景观转移,海北和海丰垦区斑块形状不断趋于简单规则,形状指数分别下降0.8和0.5,而金丰垦区形状指数上升0.4,景观破碎度方面分别呈"升—降—升"、"降—升—降"和"升—降"趋势。围垦前,各垦区景观面积和斑块形状变化差异不大,而景观破碎度变化差异明显;围垦期间各垦区景观格局变化一致;围垦后,各垦区除非受新一轮人类活动干扰,其景观格局基本维持围垦末期状态。展开更多
We aimed to study the association between sperm DNA fragmentation and recurrent pregnancy loss(RPL)in the Chinese population via a retrospective observational study of Chinese couples who had experienced RPL between M...We aimed to study the association between sperm DNA fragmentation and recurrent pregnancy loss(RPL)in the Chinese population via a retrospective observational study of Chinese couples who had experienced RPL between May 2013 and August 2018.The study population included 461 men from couples with RPL and 411 men from a control group(couples with clinical pregnancy via in v/tro fertiIization owing to female causes).Routine semen analysis,sperm chromatin analysis,and microscopic(high-power)morphological analysis were performed using semen samples.Semen samples were assessed for volume,sperm count,and motility.The sperm DNA fragmentation index(DFI)was calculated,and the median DFI was obtained.Men were categorized as having normal(37.8%;DFI<15.0%),moderate(33.6%;15.0%<DFI<30.0%),or severe(28.6%;DFI A30.0%)DNA fragmentation levels.The percentage of men with severe DNA fragmentation was significantly higher in the RPL(42.3%)group than that in the control group(13.1%),whereas the percentage of men with normal levels of DNA fragmentation was significantly lower in the RPL group(22.8%)tha n that in the control group(54.7%).Subsequent analysis also dem on strated that the sperm DNA fragmentation rate had a moderate reverse correlation with the sperm progressive motility rate(r=-0.47,P<0.001)and the total motile sperm count(r=-0.31,P<0.001).We found a positive correlation between RPL and sperm DNA fragmentation.The results suggest that increased sperm DNA damage is associated with RPL.展开更多
基金This work was supported by grants from the National Natural Science Foundation of China(No 81100469,81671517)the Scientific Research Foundation of Shanghai Municipal Commission of Health and Planning(201840060).
文摘We aimed to study the association between sperm DNA fragmentation and recurrent pregnancy loss(RPL)in the Chinese population via a retrospective observational study of Chinese couples who had experienced RPL between May 2013 and August 2018.The study population included 461 men from couples with RPL and 411 men from a control group(couples with clinical pregnancy via in v/tro fertiIization owing to female causes).Routine semen analysis,sperm chromatin analysis,and microscopic(high-power)morphological analysis were performed using semen samples.Semen samples were assessed for volume,sperm count,and motility.The sperm DNA fragmentation index(DFI)was calculated,and the median DFI was obtained.Men were categorized as having normal(37.8%;DFI<15.0%),moderate(33.6%;15.0%<DFI<30.0%),or severe(28.6%;DFI A30.0%)DNA fragmentation levels.The percentage of men with severe DNA fragmentation was significantly higher in the RPL(42.3%)group than that in the control group(13.1%),whereas the percentage of men with normal levels of DNA fragmentation was significantly lower in the RPL group(22.8%)tha n that in the control group(54.7%).Subsequent analysis also dem on strated that the sperm DNA fragmentation rate had a moderate reverse correlation with the sperm progressive motility rate(r=-0.47,P<0.001)and the total motile sperm count(r=-0.31,P<0.001).We found a positive correlation between RPL and sperm DNA fragmentation.The results suggest that increased sperm DNA damage is associated with RPL.
