Changes in the soil microbial communities of different soil aggregations after vegetation restoration in a semiarid grassland,China

Soil aggregate fractions can regulate microbial community composition and structure after vegetation restoration.However,there has been less focus on the effects of soil aggregate fractions on the distributions of microbial communities.Here,we used phospholipid fatty acid(PLFA)analysis to explore the effects of different years of vegetation restoration(a 35-year-old Thymus mongolicus community(Re-35yrs)and a 2-year-old nongrazing grassland(Ug-2yrs))on microbial communities within different soil aggregate sizes(<0.25 mm,0.25–1 mm,1–2 mm,2–3 mm,3–5 mm and>5 mm).The results indicated that the amount of total PLFA in Re-35yrs was 10 times greater than that in Ug-2yrs.The soil aggregate stability increased with increasing duration of vegetation restoration.In Re-35yrs,the total PLFA shown an increase as the soil aggregate size increased,and the highest values were observed in 3–5 mm.Ug-2yrs differed from Re-35yrs,the soil microbial diversity was higher in medium particle sizes(1–2 mm and 2–3 mm)and lower in microaggregates(<0.25 mm and 0.25–1 mm)and macroaggregates(3–5 mm and>5 mm).Soil microbial diversity was highest in large particle size aggregates,which resulted in low environmental stress and strong stability.The same tendency was observed in the high values of cyc/prec,S/M and soil organic matter,which indicated a lower turnover speed(F/B)of fungal energy utilization and a higher fixation rate.After years of natural restoration,the soil microbial community generally transformed from nutrient-rich to heterotrophdominant,especially in microaggregates(reflected in the G^(+)/G^(–)ratio).

Establishment and Application of Heminested RT-PCR Assay for Detection of Mosquito-Borne Flavivirus—Guizhou Province,China,2018

Introduction:Mosquito-borne flavivirus can lead to serious infectious diseases worldwide and cause high mortality and disability.In order to strengthen epidemiological investigation of flavivirus and meet the needs of early warning of diseases,a simple,rapid,and sensitive detection method needs to be established to prevent and control mosquito-borne diseases.Methods:Using the NS5 gene of flavivirus in GenBank,3 universal primers targeting the conserved regions were designed.The complementary DNAs(cDNAs)of Japanese encephalitis virus(JEV),dengue virus(DENV),West Nile virus(WNV),and yellow fever virus(YFV)were used as the template to optimize the reaction conditions.A heminested reversetranscriptase polymerase chain reaction(hnRT-PCR)was established to verify the sensitivity and specificity of this method and to detect field-caught mosquitoes.Results:Our results showed that this method exhibited better specificity,higher sensitivity,and the ability to detect multiple viruses simultaneously.The lowest detection limit of JEV,DENV-2,YFV,and WNV was 3×10^(4),3×10^(6),3×10^(5),and 3×10^(4)copies/μL,respectively.Mosquito-borne flavivirus was successfully detected in the field-caught mosquito samples using the method established in this study.Discussion:The hnRT-PCR method established in this study can be employed for the rapid detection of flavivirus and provide technical support for early and rapid diagnosis of mosquito-borne flavivirus.