Effect of ENSO-driven precipitation on population irruptions of the Yangtze vole Microtus fortis calamorum in the Dongting Lake region of China

The Yangtze vole(Microtus fortis Buechner,1889)is a small herbivore species that inhabits lake beaches in the Dongting Lake region along the Yangtze River in Southern China.Its population shows strong oscillations during the wet season due to summer precipitation-induced immigration away from the lake into adjacent rice fields.The effect of El Niño-Southern Oscillation-driven precipitation on population abundance and growth of the vole species is not fully understood.We undertook an analysis of the combined data of 4 time series covering 1981–2006 from 4 different sites and a separate analysis on a single time series(1981–2006)from one site.Our results demonstrate that a dual effect of El Niño-Southern Oscillation-driven precipitation on the population abundance of voles is timedependent:precipitation in the current year has a positive effect,whereas precipitation in the previous year has a negative effect.The dual effect of precipitation on vole population is well explained by the unique interactions among vole population,precipitation water level and the lake beach habitat around Dongting Lake.We found that drier than average weather of the previous year benefited voles because their breeding habitats,lake beaches,were exposed for long stretches of time.Wet weather was found to increase the number of voles inhabiting rice fields because as the water level of the lake rose they were forced from beaches into surrounding rice fields.Summer precipitation in the Dongting Lake region was found to be positively associated with the sea surface temperature(SST)of the eastern tropical Pacific Ocean of the previous year and winter SST and spring SST of the current year.Annual rates of increase in the vole population of the reconstructed time series are negatively associated with the vole abundance and autumn precipitation of the previous year and winter precipitation of the current years.These results suggest that both extrinsic and density-dependent intrinsic factors may affect population dynamics of the Yangtze voles.

Genome assembly and transcriptome analysis provide insights into the antischistosome mechanism of Microtus fortis

Microtus fortis is the only mammalian host that exhibits intrinsic resistance against Schistosoma japonicum infection.However,the underlying molecular mechanisms of this resistance are not yet known.Here,we perform the first de novo genome assembly of M.fortis,comprehensive gene annotation analysis,and evolution analysis.Furthermore,we compare the recovery rate of schistosomes,pathological changes,and liver transcriptomes between M.fortis and mice at different time points after infection.We observe that the time and type of immune response in M.fortis are different from those in mice.M.fortis activates immune and inflammatory responses on the 10th day post infection,such as leukocyte extravasation,antibody activation,Fc-gamma receptor-mediated phagocytosis,and the interferon signaling cascade,which play important roles in preventing the development of schistosomes.In contrast,an intense immune response occurrs in mice at the late stages of infection and could not eliminate schistosomes.Infected mice suffer severe pathological injury and continuous decreases in cell cycle,lipid metabolism,and other functions.Our findings offer new insights into the intrinsic resistance mechanism of M.fortis against schistosome infection.The genome sequence also provides the basis for future studies of other important traits in M.fortis.

不同性别东方田鼠组织器官中乙醇脱氢酶分析

为研究农林地区典型害鼠生理生化特征,采用PAGE电泳对不同性别东方田鼠(Microtus fortis)各组织器官中的乙醇脱氢酶分布建立电泳谱图并进行活性分析。结果表明,不同性别东方田鼠各组织器官中均有乙醇脱氢酶表达,同时该酶在不同性别东方田鼠间表达有一定差异。

Immunological characteristics of natural resistance in Microtus fortis to infection with Schistosoma japonicum

Objective To explore the immunological characteristics of natural resis tance to Schistosoma japonicum infection in Microtus fortis (MF) living in the Dongting Lake area Methods Passive transfer of sera from uninfected laboratory bred MF (BM F) to albinao mice (AM) was performed to observe the acquired protection Sodiu m dodecyl sulfatepolyacrylamide gel electrophoresis (SDSPAGE) and enzymelin ked immunoblotting (ELIB) methods were used to recognize 4 different lifecycle stage antigens of S japonicum by sera from wild MF (WMF), BMF, BMFi3 and BMFi9 Tests were also performed on in vitro killing effect of sera and/or lymphocytes from BMF an d WMF to schistosomulae; quantitative determination of C3 and C4 by immuno turb idometry, and interleukin4 (IL4) and antibodies to the 4 stage antigens in s era from WMF, BMF and infected BMF by ELISA Results Compared with the control group, stool eggs per gram (EPG) of A M in the test group was significantly reduced by 8154%, miracidium hatching rate, by 5 0 67%, liver egg counts, by 7207%, the diameter of hepatic egg granuloma, by 7 0 39?m Western blotting probed with the 4 MF sera all revealed 7 specific ban d s for SSA, 3 for AWA and SEA, but none for CA antigens The sera and/or lymphoc yte s from WMF and BMF gave obvious killing effects on schistosomulae with an adjust ed death rate of 6412%-7883% The levels ofnatural antibodiesproduced b y MF to S japonicum were in the following order: antiSSA>antiAWA>antiS EA>an tiCA, all of which increased significantly after the infection Serum levels o f C3, C4 and IL4 in uninfected BMF were significantly higher than those in AM After infection, levels of C3 and C4 were further increased respective ly by 7283% and 29549% in the 4th week and IL4 by 30383% in the 9th day Conclusions Immunological characteristics of innate resistance in M f o rtis to S japonicum infection were existed with no significant difference betw een WMF and BMF