Heterogeneous two-sided effects of different types of environmental regulations on carbon productivity in China.

In the context of globalization, the importance of enhancing carbon productivity is becoming increasingly evident. The study is a continuation of previous studies on the relationship between environmental regulations and carbon productivity. Based on a dataset of 30 provinces in China from 2006 to 2018, the paper decomposes the two-sided effects of command-and-control and market-based environmental regulations on carbon productivity. First, empirical research shows that the average positive effect of command-and-control environmental regulation on carbon productivity is 0.0158, which is much less than the average of negative effect of 0.0697, highlighting mainly the negative effect on carbon productivity. Conversely, the positive effect of market-based environmental regulation on carbon productivity is 0.0691, much greater than the negative effect of 0.0038, which highlights the obvious positive impact characteristics. Overall, the net effect of command-and-control environmental regulation on carbon productivity is -0.0541, and net effect of market-based environmental regulation on carbon productivity is 0.0653. Second, the negative impact of command-and-control environmental regulations on carbon productivity underwent a "back-to-N" change process in 2006-2018, while the driving effect of market-based environmental regulation on carbon productivity increased continuously during the 2006-2018 period. Third, most of the regions with high negative effects of command-and-control environmental regulation on carbon productivity tend to be resource-intensive and carbon-intensive, while the positive effects of market-based environmental regulation on carbon productivity have no obvious geographical agglomeration characteristics. Fourth, the continuous improvement of regional development conditions is clearly conducive to the continuous reduction of the negative effects of command-and-control environmental regulation on carbon productivity, while the higher positive effects of market-based environmental regulation on carbon productivity at this stage need to meet different regional condition intervals.

The two-sided effects of foreign direct investment on carbon emissions performance in China.

Climate change caused by rapid increases in greenhouse gas concentrations is now a global challenge. Foreign direct investment (FDI), as a key player in global economic growth, is a major contributor to carbon emissions. Based on panel data of 30 provinces in China collected from 2007 to 2018, this paper uses the two-tier stochastic frontier model to analyse the opposing two-sided effects of FDI on carbon emission performance and calculates their combined effects. The empirical study shows that FDI has both a promoting and an inhibiting effect on carbon emission performance, and the overall effect is characterized by less of an inhibiting effect than a promoting effect, resulting in the positive driving characteristic of the combined effect. The average inhibiting effect is 0.0402, and the average promoting effect is 0.1065, causing the comprehensive effect of FDI on carbon emission performance to have an average value of 0.0663. The empirical results also show that the promoting effects of FDI are greater than the inhibiting effects in most regions; however, after 2013, the level of the promoting effect declined overall. There are regional differences in the combined effects of FDI on carbon emission performance, and the driving effects present in the central and western regions of China are significantly lower than that in the eastern region. Based on the research conclusions, while promoting a "green" revolution in FDI utilization patterns, it is necessary to strengthen the interaction mechanism between FDI and low-carbon economic development in China and to enhance the driving effect of FDI on carbon emission performance in China.

cDNA cloning, expression and bioinformatical analysis of Tssk genes in tree shrews.

Tree shrews are more closely related to primate animals than rodents in many aspects. In addition, they also possess several advantageous characteristics including small body size, high brain-to-body mass ratio, low cost of feeding and maintenance, short reproductive cycle and life span, which make them promising novel laboratory animals to replace more precious larger primate animals. Testis-specific serine/threonine kinase (Tssk) plays important roles in spermatogenesis and/or the regulation of sperm function. However, studies on Tssk in tree shrews have not been reported yet. In the present study, the full-length sequences of five members of the Tssk family in tree shrews were cloned and their CDS region sequences were analyzed by basic bioinformatics. The phylogenetic tree and prokaryotic protein expression system of Tssk gene of tree shrews were constructed. The mRNA expressions of Tssk genes in 11 tissues/organs from tree shrews were studied. The results showed that: 1. the length of the CDS region of tree shrew Tssk gene for Tssk1B, Tssk2, Tssk3 (variant X1 / X2), Tssk4 (variant X1 / X2) and Tssk6 is 1080bp, 1077bp, 867 / 807bp, 1014 / 984bp, 822bp, respectively, encoding 359, 358, 288/268, 337/327 and 273 amino acids, respectively; the cloned sequences of Tssk genes have been submitted to GenBank with the following accession numbers: KX091161(Tssk1B), KX091162(Tssk2), KX091163(Tssk3 variant X1)/KX091164(Tssk3 variant X2), KX091165(Tssk4variant X1)/KX091166(Tssk4variant X2), KX091160(Tssk6). 2. All tree shrew Tssk proteins distribute in cytoplasm, indicating that they are hydrophilic and non-secretory proteins, with multiple phosphorylation sites of serine and/or threonine. In addition, they are all mixed proteins with similar tertiary structures sharing a highly conserved functional domain of S_TKc (Serine/Threonine protein kinases, catalytic domain). 3.The molecular phylogenetic tree of five Tssk genes in tree shrews indicates that they are neither rodent nor primate animal, but are closely related to primate animals. 4. Five members of the Tssk recombinant proteins in tree shrews were successfully obtained using the constructed prokaryotic protein expression system. 5. Five Tssk genes are specifically expressed in the testis and/or sperm of tree shrews. Additionally, small amount of Tssk1B was expressed in several tissues other than testis and sperm. Limited mRNA levels of Tssk2 and Tssk4 were expressed in the brain, while mRNA of Tssk3 or Tssk6 could only be detected in the testis and sperm. This study will provide fundamental data on reproductive biology of tree shrews, which paves a way for further studying Tssk's biological function in this novel model animal.

Cryo-EM structure of the SARS coronavirus spike glycoprotein in complex with its host cell receptor ACE2.

The trimeric SARS coronavirus (SARS-CoV) surface spike (S) glycoprotein consisting of three S1-S2 heterodimers binds the cellular receptor angiotensin-converting enzyme 2 (ACE2) and mediates fusion of the viral and cellular membranes through a pre- to postfusion conformation transition. Here, we report the structure of the SARS-CoV S glycoprotein in complex with its host cell receptor ACE2 revealed by cryo-electron microscopy (cryo-EM). The complex structure shows that only one receptor-binding domain of the trimeric S glycoprotein binds ACE2 and adopts a protruding "up" conformation. In addition, we studied the structures of the SARS-CoV S glycoprotein and its complexes with ACE2 in different in vitro conditions, which may mimic different conformational states of the S glycoprotein during virus entry. Disassociation of the S1-ACE2 complex from some of the prefusion spikes was observed and characterized. We also characterized the rosette-like structures of the clustered SARS-CoV S2 trimers in the postfusion state observed on electron micrographs. Structural comparisons suggested that the SARS-CoV S glycoprotein retains a prefusion architecture after trypsin cleavage into the S1 and S2 subunits and acidic pH treatment. However, binding to the receptor opens up the receptor-binding domain of S1, which could promote the release of the S1-ACE2 complex and S1 monomers from the prefusion spike and trigger the pre- to postfusion conformational transition.

Cryo-electron microscopy structures of the SARS-CoV spike glycoprotein reveal a prerequisite conformational state for receptor binding.

The global outbreak of SARS in 2002-2003 was caused by the infection of a new human coronavirus SARS-CoV. The infection of SARS-CoV is mediated mainly through the viral surface glycoproteins, which consist of S1 and S2 subunits and form trimer spikes on the envelope of the virions. Here we report the ectodomain structures of the SARS-CoV surface spike trimer in different conformational states determined by single-particle cryo-electron microscopy. The conformation 1 determined at 4.3 Å resolution is three-fold symmetric and has all the three receptor-binding C-terminal domain 1 (CTD1s) of the S1 subunits in "down" positions. The binding of the "down" CTD1s to the SARS-CoV receptor ACE2 is not possible due to steric clashes, suggesting that the conformation 1 represents a receptor-binding inactive state. Conformations 2-4 determined at 7.3, 5.7 and 6.8 Å resolutions are all asymmetric, in which one RBD rotates away from the "down" position by different angles to an "up" position. The "up" CTD1 exposes the receptor-binding site for ACE2 engagement, suggesting that the conformations 2-4 represent a receptor-binding active state. This conformational change is also required for the binding of SARS-CoV neutralizing antibodies targeting the CTD1. This phenomenon could be extended to other betacoronaviruses utilizing CTD1 of the S1 subunit for receptor binding, which provides new insights into the intermediate states of coronavirus pre-fusion spike trimer during infection.

Identification of residues on human receptor DPP4 critical for MERS-CoV binding and entry.

Middle East respiratory syndrome coronavirus (MERS-CoV) infects host cells through binding the receptor binding domain (RBD) on its spike glycoprotein to human receptor dipeptidyl peptidase 4 (hDPP4). Here, we report identification of critical residues on hDPP4 for RBD binding and virus entry through analysis of a panel of hDPP4 mutants. Based on the RBD-hDPP4 crystal structure we reported, the mutated residues were located at the interface between RBD and hDPP4, which potentially changed the polarity, hydrophobic or hydrophilic properties of hDPP4, thereby interfering or disrupting their interaction with RBD. Using surface plasmon resonance (SPR) binding analysis and pseudovirus infection assay, we showed that several residues in hDPP4-RBD binding interface were important on hDPP4-RBD binding and viral entry. These results provide atomic insights into the features of interactions between hDPP4 and MERS-CoV RBD, and also provide potential explanation for cellular and species tropism of MERS-CoV infection.

[Effect of aluminum exposure on cognitive function in electrolytic workers and its influential factors].

OBJECTIVE: To clarify the effect of aluminum exposure on the cognitive function in electrolytic workers and the prevalence of mild cognitive impairment (MCI) among them by prevalence survey, and to investigate its influential factors. METHODS: Sixty-six retired workers from the electrolysis workshop of an electrolytic aluminum plant were selected as an aluminum exposure group, while 70 retired workers from a flour mill in the same region were selected as a control group. MCI patients were screened out by Mini-Mental State Examination (MMSE); the blood aluminum level was measured by inductively coupled plasma-mass spectrometry; multivariate statistical analysis was used to investigate the influential factors for MMSE scores and the correlation between blood aluminum level and MCI prevalence. RESULTS: The aluminum exposure group showed a significantly higher blood aluminum level than the control group (25.18 ± 2.65 µg/L vs 9.97 ± 2.83 µg/L, P < 0.01). The total MMSE score of the aluminum exposure group (26.13 ± 2.57) was significantly lower than that of the control group (27.89 ± 1.91) (P < 0.05), particularly the scores on time and place orientation, short-term memory, calculation ability, and language skill (P < 0.05). The detection rate of MCI was significantly higher in the aluminum exposure group (18.2%) than in the control group (5.7%) (P < 0.01). The main influential factors for MMSE scores were gender, age, education level, and blood aluminum level. The logistic regression analysis indicated that the MCI prevalence was significantly correlated with blood aluminum level in the study population (OR = 1.168, P < 0.01). CONCLUSION: Long-term exposure to aluminum can cause cognitive disorders in electrolytic workers and may be one of the risk factors for MCI. Advanced age, male, low education level, and high blood aluminum level may be high-risk factors for cognitive impairment.