Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctu...Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctuations to the composition of the landscape.It states that as ROMPA decreases(fragmentation increases),vole population fluctuations will increase(including the tendency to display multi-annual cycles in abundance)because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season.To date,only comparative observations in the field have supported the hypothesis.This paper reports the results of the first experimental test.I used prairie voles,Microtus ochrogaster,and mowed grassland to create model landscapes with 3 levels of ROMPA(high with 25%mowed,medium with 50%mowed and low with 75%mowed).As ROMPA decreased,distances between patches of favorable habitat(high cover)increased owing to a greater proportion of unfavorable(mowed)habitat.Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed(inversely density dependent emigration and,as ROMPA decreased,increased per capita mortality and decreased per capita movement between optimal patches).Nevertheless,contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability,5 years of trapping indicated that variability was lowest with medium ROMPA.The design of field experiments may never be perfect,but these results indicate that the ROMPA hypothesis needs further rigorous testing.展开更多
为探究不同复性方法制备的重组大肠杆菌外膜蛋白A(rOmpA)的免疫原性,研究分别用纯化的β-环糊精复性rOmpA(β-rOmpA)、吐温-20复性rOmpA(T-rOmpA)和包涵体形式rOmpA(I-rOmpA)作为抗原,与弗氏佐剂乳化后肌肉注射免疫接种小鼠。通过检测...为探究不同复性方法制备的重组大肠杆菌外膜蛋白A(rOmpA)的免疫原性,研究分别用纯化的β-环糊精复性rOmpA(β-rOmpA)、吐温-20复性rOmpA(T-rOmpA)和包涵体形式rOmpA(I-rOmpA)作为抗原,与弗氏佐剂乳化后肌肉注射免疫接种小鼠。通过检测血清特异性抗体、脾淋巴细胞分泌细胞因子及攻毒试验进行免疫效力评价。结果,β-rOmpA免疫组小鼠血清抗体水平高于T-rOmpA免疫组和I-rOmpA免疫组(P<0.05);三种抗原免疫均能提高小鼠淋巴细胞分泌IFN-γ水平,且在体外由rOmpA刺激下,β-rOmpA免疫组小鼠产生的IFN-γ、IL-17A水平显著高于T-rOmpA和I-rOmpA免疫组(P<0.05);用E.coli 2002-1菌株腹腔攻毒后,β-rOmpA免疫组小鼠肝、脾、肺、肾中的细菌定植量显著低于T-rOmpA免疫组和I-rOmpA免疫组(P<0.001);攻毒后第2 d PBS对照组小鼠免疫保护率为0时,β-rOmpA免疫组为60%,T-rOmpA免疫组为40%,I-rOmpA免疫组为30%。结果表明,β-环糊精复性纯化的rOmpA免疫原性最好,诱导机体产生免疫应答和免疫保护作用最强。展开更多
文摘Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctuations to the composition of the landscape.It states that as ROMPA decreases(fragmentation increases),vole population fluctuations will increase(including the tendency to display multi-annual cycles in abundance)because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season.To date,only comparative observations in the field have supported the hypothesis.This paper reports the results of the first experimental test.I used prairie voles,Microtus ochrogaster,and mowed grassland to create model landscapes with 3 levels of ROMPA(high with 25%mowed,medium with 50%mowed and low with 75%mowed).As ROMPA decreased,distances between patches of favorable habitat(high cover)increased owing to a greater proportion of unfavorable(mowed)habitat.Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed(inversely density dependent emigration and,as ROMPA decreased,increased per capita mortality and decreased per capita movement between optimal patches).Nevertheless,contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability,5 years of trapping indicated that variability was lowest with medium ROMPA.The design of field experiments may never be perfect,but these results indicate that the ROMPA hypothesis needs further rigorous testing.
文摘为探究不同复性方法制备的重组大肠杆菌外膜蛋白A(rOmpA)的免疫原性,研究分别用纯化的β-环糊精复性rOmpA(β-rOmpA)、吐温-20复性rOmpA(T-rOmpA)和包涵体形式rOmpA(I-rOmpA)作为抗原,与弗氏佐剂乳化后肌肉注射免疫接种小鼠。通过检测血清特异性抗体、脾淋巴细胞分泌细胞因子及攻毒试验进行免疫效力评价。结果,β-rOmpA免疫组小鼠血清抗体水平高于T-rOmpA免疫组和I-rOmpA免疫组(P<0.05);三种抗原免疫均能提高小鼠淋巴细胞分泌IFN-γ水平,且在体外由rOmpA刺激下,β-rOmpA免疫组小鼠产生的IFN-γ、IL-17A水平显著高于T-rOmpA和I-rOmpA免疫组(P<0.05);用E.coli 2002-1菌株腹腔攻毒后,β-rOmpA免疫组小鼠肝、脾、肺、肾中的细菌定植量显著低于T-rOmpA免疫组和I-rOmpA免疫组(P<0.001);攻毒后第2 d PBS对照组小鼠免疫保护率为0时,β-rOmpA免疫组为60%,T-rOmpA免疫组为40%,I-rOmpA免疫组为30%。结果表明,β-环糊精复性纯化的rOmpA免疫原性最好,诱导机体产生免疫应答和免疫保护作用最强。