Simulation of permafrost changes on the Qinghai–Tibet Plateau, China, over the past three decades

Permafrost is one of the largest elements of the terrestrial cryosphere and is extremely sensitive to climate change. Based on mean annual ground temperature (MAGT) data from 189 boreholes on the Qinghai–Tibet Plateau (QTP), terrain factors, and climate data from China Meteorological Forcing Dataset, we propose a new mean annual ground air temperature (MAGAT) statistical model between meteorological parameters with subsurface temperatures to simulate permafrost distribution and variation of MAGT on the QTP over the past three decades (1981–2010). Validation of the model with MAGT data from 13 boreholes and permafrost maps of the QTP indicated that the MAGAT model is applicable to simulate the distribution and evolution of permafrost on the QTP. Simulation results show that the spatiotemporal MAGT of permafrost significantly increased by 0.37°C, or 0.25°C/10 yr, and the total area of permafrost decreased by 2.48 × 105 km2 on the QTP over the past three decades. Regionally, the changes of permafrost in the southwestern QTP were greater than other regions of the QTP

Low within-population genetic diversity and high genetic differentiation among populations of the endangered plant Tetracentron sinense Oliver revealed by inter-simple sequence repeat analysis

International audienceAbstractKey messageTetracentron sinenseOliver, an endangered species from China, displays a low within-population genetic diversity and high genetic differentiation among populations, and the existing populations could be divided into three conservation and management units.ContextThe endangered tree Tetracentron sinense Oliver has great value; however, little is known regarding the within-population genetic diversity and differentiation among T. sinense populations.AimsWe examined the genetic diversity and differentiation of T. sinense wild populations, and we tested the effect of small-size population on the level of genetic diversity within these populations.MethodsUsing inter-simple sequence repeat (ISSR), we assessed the genetic variation and structure among 174 individuals from 26 natural populations of T. sinense sampled across its distribution range in China.ResultsThe ISSR primers yielded 180 amplified loci (123 were polymorphic). At the species level, the percentage of polymorphic loci (PPL), Nei’s gene diversity (H), and Shannon’s information index (I) were 68.3%, 0.196 and 0.300, respectively. The average population level PPL was 20.0%, and the Na, Ne, H, and I were 1.20, 1.13, 0.076, and 0.112, respectively. AMOVA revealed high genetic differentiation among populations (52.0% of total variance, P = 0.001), consistent with the gene differentiation coefficient (Gst = 0.607) and gene flow (Nm = 0.326). The 174 individuals of the 26 T. sinense populations clustered into three groups, and T. sinense geographic and genetic distance were significantly correlated.ConclusionsT. sinense exhibited intermediate within-species genetic diversity, indicating preserved evolutionary potential. The low within-population genetic diversity and high genetic differentiation among T. sinense populations may be one of important factors causing endangerment. Three conservation units were determined based on genetic difference and structure. Inter-population introduction of individuals within units via appropriate propagation and seedling management might be an effective strategy for increasing T. sinense within-population genetic diversity and population size

Assessment of the Urban Expansion and Its Impact on the Eco-Environment—A Case Study of Hefei Municipal Area

With the advancement of urbanization, the ecological environmental changes caused by the continuous expansion of cities have become a major concern. Thus, this study is based on a remote sensing image map of Hefei city from 1984 to 2020, which is now in the process of rapid development. We constructed an index system with ecological land, ecosystem service value, ecological environment quality, urban land expansion coefficient, urban heat island rate index, total pollutant emissions, ecological pressure, and ecological deficit, and then evaluated the ecological environment of Hefei city with the help of the entropy weight comprehensive evaluation method. The results show that (1) in the positive evaluation index, the ecological land area was reduced to half of the original area, the ecological service value was reduced by 0.37 times its initial value, and the eco-environmental index was <35 and still decreasing. (2) In the negative evaluation index, the urban heat island ratio index increased by nearly 10 times its initial value, the total emission of various pollutants increased by 6.64 times its initial value, the ecological deficit increased year by year after 1999, and the ecological pressure in 2020 increased to 3 times that in 1999. (3) The overall environmental score of the Hefei urban area has decreased by 48.6 times its initial value. The values of positive evaluation indexes are decreasing, whereas the values of negative evaluation indexes are increasing, and both these items are moving backward, leading to the decrease in the comprehensive ecological environmental score. It can be noticed that the urban expansion of Hefei has had a severe impact on the ecological environment, resulting in the continuous reduction in the ecological land area, a serious urban heat island effect, and continuous weakening of regional ecological service functions. The study results can be used for reference in alleviating the impacts of urban expansion on the environment, promoting the optimization of the urban landscape and the sustainable development of the social economy and environment

Capsid-Targeted Viral Inactivation: A Novel Tactic for Inhibiting Replication in Viral Infections

Capsid-targeted viral inactivation (CTVI), a conceptually powerful new antiviral strategy, is attracting increasing attention from researchers. Specifically, this strategy is based on fusion between the capsid protein of a virus and a crucial effector molecule, such as a nuclease (e.g., staphylococcal nuclease, Barrase, RNase HI), lipase, protease, or single-chain antibody (scAb). In general, capsid proteins have a major role in viral integration and assembly, and the effector molecule used in CTVI functions to degrade viral DNA/RNA or interfere with proper folding of viral key proteins, thereby affecting the infectivity of progeny viruses. Interestingly, such a capsid–enzyme fusion protein is incorporated into virions during packaging. CTVI is more efficient compared to other antiviral methods, and this approach is promising for antiviral prophylaxis and therapy. This review summarizes the mechanism and utility of CTVI and provides some successful applications of this strategy, with the ultimate goal of widely implementing CTVI in antiviral research

Structures and Functions of the Envelope Glycoprotein in Flavivirus Infections

Flaviviruses are enveloped, single-stranded RNA viruses that widely infect many animal species. The envelope protein, a structural protein of flavivirus, plays an important role in host cell viral infections. It is composed of three separate structural envelope domains I, II, and III (EDI, EDII, and EDIII). EDI is a structurally central domain of the envelope protein which stabilizes the overall orientation of the protein, and the glycosylation sites in EDI are related to virus production, pH sensitivity, and neuroinvasiveness. EDII plays an important role in membrane fusion because of the immunodominance of the fusion loop epitope and the envelope dimer epitope. Additionally, EDIII is the major target of neutralization antibodies. The envelope protein is an important target for research to develop vaccine candidates and antiviral therapeutics. This review summarizes the structures and functions of ED I/II/III, and provides practical applications for the three domains, with the ultimate goal of implementing strategies to utilize the envelope protein against flavivirus infections, thus achieving better diagnostics and developing potential flavivirus therapeutics and vaccines

Freeze/Thaw-Induced Deformation Monitoring and Assessment of the Slope in Permafrost Based on Terrestrial Laser Scanner and GNSS

Most previous studies of the Qinghai-Tibet engineering corridor (QTEC) have focused on the impacts of climate change on thaw-induced slope failures, whereas few have considered freeze-induced slope failures. Terrestrial laser scanning was used in combination with global navigation satellite systems to monitor three-dimensional surface changes between 2014 and 2015 on the slope of permafrost in the QTEC, which experienced two thawing periods and a freezing period. Soil temperature and moisture sensors were also deployed at 11 depths to reveal the hydrological–thermal dynamics of the active layer. We analyzed scanned surface changes in the slope based on comparisons of multi-temporal point cloud data to determine how the hydrological–thermal process affected active layer deformation during freeze–thaw cycles, thereby comprehensively quantifying the surface deformation. During the two thawing periods, the major structure of the slope exhibited subsidence trends, whereas the major structure of the slope had an uplift trend in the freezing period. The seasonal subsidence trend was caused by thaw settlement and the seasonal uplift trend was probably due to frost heaving. This occurred mainly because the active layer and the upper permafrost underwent a phase transition due to heat transfer. The ground movements occurred approximately in the soil temperature conduction direction between the top of the soil and the permafrost table. The elevation deformation range was mainly −0.20 m to 0.20 m. Surface volume increases with heaving after freezing could have compensated for the loss of thawing twice and still led to the upward swelling of the slope. Thus, this type of slope in permafrost is dominated by frost heave. Deformation characteristics of the slope will support enhanced decision making regarding the implementation of remote sensing and hydrological–thermal measurement technologies to monitor changes in the slopes in permafrost adjacent to engineering corridors, thereby improving the understanding and assessment of hazards