Surge of severe acute respiratory syndrome coronavirus 2 infections linked to single introduction of a virus strain in Myanmar, 2020.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a major health concern globally. Genomic epidemiology is an important tool to assess the pandemic of coronavirus disease 2019 (COVID-19). Several mutations have been reported by genome analysis of the SARS-CoV-2. In the present study, we investigated the mutational and phylogenetic analysis of 30 whole-genome sequences for the virus's genomic characteristics in the specimens collected in the early phase of the pandemic (March-June, 2020) and the sudden surge of local transmission (August-September, 2020). The four samples in the early phase of infection were B.6 lineage and located within a clade of the samples collected at the same time in Singapore and Malaysia, while five returnees by rescue flights showed the lineage B. 1.36.1 (three from India), B.1.1 (one from India) and B.1.80 (one from China). However, there was no evidence of local spread from these returnees. Further, all 19 whole-genome sequences collected in the sudden surge of local transmission showed lineage B.1.36. The surge of the second wave on SARS-CoV-2 infection was linked to the single-introduction of a variant (B.1.36) that may result from the strict restriction of international travel and containment efforts. These genomic data provides the useful information to disease control and prevention strategy.

Evaluation of N2O emission from rainfed wheat field in northwest agricultural land in China.

The net greenhouse gas (NGHG) emissions and net greenhouse gas intensity (NGHGI) were investigated via the determination of nitrous oxide (N2O) emission in loess soil under rainfed winter wheat monocropping system during 3 years of field study in Northwest China. Five treatments were carried out: control (N0), conventional nitrogen (N) application (NCon), optimized N application with straw (SNOpt), optimized N application with straw and 5% of dicyanodiamide (SNOpt + DCD), and optimized N rate of slow release fertilizer with straw (SSRFOpt). Over a 3-year period, the NGHG emissions were achieved 953, 1322, 564, and 1162 kg CO2-eq ha-1, simultaneously, and the NGHGI arrived 158, 223, 86, and 191 kg CO2-eq t-1 grain in NCon, SNOpt, SNOpt + DCD, and SSROpt grain, respectively. Contrasted with conventional farming system, optimized farming methods reduced 32% of N fertilizer use without significant decrease in grain yield, but brought about 38% increase in N2O emissions, up to 28% gained in soil CH4 uptake. Thus, it was observed that the straw incorporation performs noticeable increased in N2O emissions in the winter wheat cropping season. Among the optimized N fertilizer rates compared with the SNOpt treatment, the SNOpt +DCD and SSROpt treatments decreased in N2O emissions by approximately 55% and 13%, respectively. Additionally, the N2O emission factor across over a 3-year period was 0.41 ± 0.08% derived from N fertilizer, and it was half of IPCC default values for upland corps. It is expected possibly due to low precipitation and soil moisture with the monocropping system. The 25% higher in the amount of rainfall (almost 300 mm in 2013-2014) during a cropping season underwent into 1-2-fold increase in N2O emissions from N-fertilized plots. As the statistical differences among annual cumulative emissions coincided with that during winter wheat growing season, it can be concluded that crop growing season is a vital important period for the determination of N2O emissions from under rainfed monocropping system.