Short tandem repeats (STRs) are short tandemly repeated DNA sequences that involve a repetitive unit of 1–6 bp. Because of their polymorphisms and high mutation rates, STRs are widely used in biological research. Strand-slippage replication is the predominant mutation mechanism of STRs, and the stepwise mutation model is regarded as the main mutation model. STR mutation rates can be influenced by many factors. Moreover, some trinucleotide repeats are associated with human neurodegenerative diseases. In order to deepen our knowledge of these diseases and broaden STR application, it is essential to understand the STR mutation process in detail. In this review, we focus on the current known information about STR mutation.

No abstract

No abstract

Abstract. Desert riparian forests are the main restored vegetation community in Heihe River basin. They provide critical habitats and a variety of ecosystem services in this arid environment. Since desert riparian forests are also sensitive to disturbance, examining the spatial distribution and temporal variation of these forests and their influencing factors is important to determine the limiting factors of vegetation recovery after long-term restoration. In this study, field experiment and remote sensing data were used to determine the spatial distribution and temporal variation of desert riparian forests and their relationship with the environmental factors.

Abstract. Wildfires are an important contributor to atmospheric aerosols in Australia and could significantly affect the regional and even global climate. This study investigates the impact of fire events on aerosol properties along with the long-range transport of biomass-burning aerosol over Australia using multi-year measurements from Aerosol Robotic Network (AERONET) at 10 sites over Australia, a satellite dataset derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), reanalysis data from Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2), and back-trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The fire count, fire radiative power (FRP), and aerosol optical depth (AOD) showed distinct and consistent interannual variations, with high values during September–February (biomass-burning period, BB period) and low values during March–August (non-biomass-burning period, non-BB period) every year. Strong correlation (0.62) was found between FRP and AOD over Australia. Furthermore, the correlation coefficient between AOD and fire count was much higher (0.63–0.85) during October–January than other months (−0.08 to 0.47). Characteristics of Australian aerosols showed pronounced differences between the BB period and non-BB period. AOD values significantly increased and fine-mode aerosol dominated during the BB period, especially in northern and southeastern Australia. Carbonaceous aerosol was the main contributor to total aerosols during the BB period, especially in September–December when carbonaceous aerosol contributed the most (30.08 %–42.91 %). Aerosol size distributions showed a bimodal character, with both fine and coarse aerosol particles generally increasing during the BB period. The megafires during the BB period of 2019/2020 further demonstrated the significant impact of wildfires on aerosol properties, such as the extreme increase in AOD for most of southeastern Australia, the dominance of fine particle aerosols, and the significant increase in carbonaceous and dust aerosols in southeastern and central Australia, respectively. Moreover, smoke was found to be the dominant aerosol type detected at heights from 2.5 to 12 km in southeastern Australia in December 2019 and at heights from roughly 6.2 to 12 km in January 2020. In contrast, dust was detected more frequently at heights from 2 to 5 km in November 2019 and January and February 2020. A case study emphasized that the transport of biomass-burning aerosols from wildfire plumes in eastern and southern Australia significantly impacted the aerosol loading, aerosol particle size, and aerosol type of central Australia.

In late January 2020, China’s rapid and strict control measures to curb the COVID‐19 spread led to a sharp halt in socio‐economic activity and a significant reduction in emissions. Using the ground‐based observational data, the authors synergistically quantify the nation‐wide variations of major air pollutant as well as meteorology during and after the lockdown. Their concentrations (except O3) exhibited significant reduction during February and March 2020, by more than 24% during the lockdown compared with the earlier time period and by more than 17% compared with that in the same period in 2019. In contrast, ozone increased rapidly by about 60% across the country during the lockdown. Abnormal increases in carbon monoxide and particulate matter concentrations in southwest China are attributed to the severe wildfires in Southeast Asia. The concentration of air pollutants bounced back rapidly after the full‐scale reopen in March 2020, indicating the decisive role of emissions in the pollution formation.

Using hourly observation data of precipitation and PM2.5 at 12 sites in Beijing from 2015 to 2017, this study investigates the impacts of different types of precipitation on PM2.5 mass concentration, along with the characteristics of precipitation and PM2.5. There were totally 91–123 precipitation events annually, 69.7–79.4% of which has precipitation amount less than 5 mm. By investigating the differences of PM2.5 mass concentration between 1 hr after and before the precipitation events, this study finds distinct impacts of different types of precipitation on PM2.5 mass concentration. For precipitation events with amount of 0.1–0.5 mm, PM2.5 mass concentration increased with precipitation amount with a rate of 0.85 μg/m3 per 0.1 mm. For precipitation events with amount of 0.5–10 mm, there was no clear relationship between precipitation amount and PM2.5 mass concentration. For precipitation events with amount larger than 10 mm, PM2.5 mass concentration decreased with precipitation amount with a rate of 0.17 μg/m3 per 1 mm. Further analysis shows that weak precipitation less than 10 mm increased PM10, and heavy precipitation larger than 10 mm decreased PM10. The aerosol amount also affects the response of PM2.5 to precipitation, with weak pollution prone to increase with precipitation and heavy pollution prone to decrease with precipitation. Likely mechanisms are discussed, which include the aerosol hygroscopic growth and gas‐particle conversion that increase aerosol amount and precipitation scavenging that decreases aerosol amount. Shortly, the mechanisms that increase (decrease) aerosol amount more probably dominate when precipitation is light (heavy).

No abstract