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The flagella of mammalian sperm display non-planar, asymmetric beating, in contrast to the planar, symmetric beating of flagella from sea urchin sperm and unicellular organisms. The molecular basis of this difference is unclear. Here, we perform in situ cryo-electron tomography of mouse and human sperm, providing the highest-resolution structural information to date. Our subtomogram averages reveal mammalian sperm-specific protein complexes within the microtubules, the radial spokes and nexin-dynein regulatory complexes. The locations and structures of these complexes suggest potential roles in enhancing the mechanical strength of mammalian sperm axonemes and regulating dynein-based axonemal bending. Intriguingly, we find that each of the nine outer microtubule doublets is decorated with a distinct combination of sperm-specific complexes. We propose that this asymmetric distribution of proteins differentially regulates the sliding of each microtubule doublet and may underlie the asymmetric beating of mammalian sperm.

Objective To investigate the prognostic value and clinical significance of preoperative prognostic nutritional index （PNI） in patients with extensive burns. Methods Clinical data of 56 patients with extensive burns were retrospectively analyzed，and they were divided into the survival group （n=37） and death group （n=19） according to clinical outcomes. Baseline data and relevant laboratory indexes at preoperative 1 d were collected. PNI was calculated using the following equation： serum albumin level （g/L） +5×total lymphocyte count （×109/L）. Clinical data were statistically compared between two groups. The influencing factors of clinical prognosis were identified by univariate and multivariate Logistic regression analyses. The predictive value of preoperative PNI for clinical prognosis of patients with extensive burns was evaluated by the ROC curve. The area under the ROC curve （AUC） represents the accuracy of prediction. All patients were divided into the high and low PNI groups according to the optimal cut-off value of preoperative PNI. The survival curve was drawn by Kaplan Meier method to predict the differences in 90-d survival rate between two groups. Results Among 56 patients，19 （33.93%） died within postoperative 90 d. There were significant differences in burn area，lymphocyte count and preoperative PNI between the death and survival groups （all P<0.05）. In the death group，burn area was larger，lymphocyte count and preoperative PNI were lower than those in the survival group. There were no significant differences in age，sex，CRP，white blood cell count，creatinine，PLR，albumin levels and the incidence of respiratory tract injury between two groups. Univariate Logistic regression analysis showed that burn area，lymphocyte count and preoperative PNI were the risk factors of death. Multivariate Logistic regression analysis indicated that burn area and preoperative PNI were the independent risk factors for death. The optimal cut-off value of preoperative PNI to predict death in patients with extensive burns was 34.45. The 90-d survival rate of patients with PNI≤34.45 was significantly lower than that of their counterparts with PNI>34.45. Conclusions Preoperative PNI is associated with 90-d death rate in patients with extensive burns. The 90-d survival rate of patients with low PNI is lower than that of those with high PNI. These findings indicate that it is of significance to identify preoperative PNI for patients with extensive burns，which can provide reference for selecting the optimal timing for surgery，accelerate wound healing and reduce the death rate of patients with extensive burns.

This paper first explains the tennis technical action representation and matching technology, using the Euler angle method to represent the coordinates of the tennis action gesture, realizing the deconstruction of the action gesture through the gesture-solving algorithm, and then using the weighted Euclidean distance to match the tennis gesture to the action. Secondly, we constructed the tennis technical movement training strategy for colleges and universities based on the task-driven teaching method, and gave the teaching experiment method to analyze the effectiveness of the strategy. Finally, the data was analyzed by examining the muscle characteristics of tennis technical movements and the teaching effect of task-driven teaching. The results showed that the maximal EMG integral value of the muscles was 32.91uV.s in the level 1 group and 87.91uV.s in the level 2 group, and the maximal angular velocity of the ankle-knee-hip joints was 645.23±189.42°/s and the minimum angular velocity of the hip joints was 461.87±115.08°/s in all the landing modes. 115.08°/s. The task-driven teaching method can effectively improve the students’ tennis learning and technical level and enhance the quality of tennis technical teaching in colleges and universities.

The SARS-CoV-2 protein Nsp2 has been implicated in a wide range of viral processes, but its exact functions, and the structural basis of those functions, remain unknown. Here, we report an atomic model for full-length Nsp2 obtained by combining cryo-electron microscopy with deep learning-based structure prediction from AlphaFold2. The resulting structure reveals a highly-conserved zinc ion-binding site, suggesting a role for Nsp2 in RNA binding. Mapping emerging mutations from variants of SARS-CoV-2 on the resulting structure shows potential host-Nsp2 interaction regions. Using structural analysis together with affinity tagged purification mass spectrometry experiments, we identify Nsp2 mutants that are unable to interact with the actin-nucleation-promoting WASH protein complex or with GIGYF2, an inhibitor of translation initiation and modulator of ribosome-associated quality control. Our work suggests a potential role of Nsp2 in linking viral transcription within the viral replication-transcription complexes (RTC) to the translation initiation of the viral message. Collectively, the structure reported here, combined with mutant interaction mapping, provides a foundation for functional studies of this evolutionary conserved coronavirus protein and may assist future drug design.

Neutralizing agents against SARS-CoV-2 are urgently needed for the treatment and prophylaxis of COVID-19. Here, we present a strategy to rapidly identify and assemble synthetic human variable heavy (VH) domains toward neutralizing epitopes. We constructed a VH-phage library and targeted the angiotensin-converting enzyme 2 (ACE2) binding interface of the SARS-CoV-2 Spike receptor-binding domain (Spike-RBD). Using a masked selection approach, we identified VH binders to two non-overlapping epitopes and further assembled these into multivalent and bi-paratopic formats. These VH constructs showed increased affinity to Spike (up to 600-fold) and neutralization potency (up to 1,400-fold) on pseudotyped SARS-CoV-2 virus when compared to standalone VH domains. The most potent binder, a trivalent VH, neutralized authentic SARS-CoV-2 with a half-maximal inhibitory concentration (IC50) of 4.0 nM (180 ng ml-1). A cryo-EM structure of the trivalent VH bound to Spike shows each VH domain engaging an RBD at the ACE2 binding site, confirming our original design strategy.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus enters host cells via an interaction between its Spike protein and the host cell receptor angiotensin-converting enzyme 2 (ACE2). By screening a yeast surface-displayed library of synthetic nanobody sequences, we developed nanobodies that disrupt the interaction between Spike and ACE2. Cryo-electron microscopy (cryo-EM) revealed that one nanobody, Nb6, binds Spike in a fully inactive conformation with its receptor binding domains locked into their inaccessible down state, incapable of binding ACE2. Affinity maturation and structure-guided design of multivalency yielded a trivalent nanobody, mNb6-tri, with femtomolar affinity for Spike and picomolar neutralization of SARS-CoV-2 infection. mNb6-tri retains function after aerosolization, lyophilization, and heat treatment, which enables aerosol-mediated delivery of this potent neutralizer directly to the airway epithelia.

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a grave threat to public health and the global economy. SARS-CoV-2 is closely related to the more lethal but less transmissible coronaviruses SARS-CoV-1 and Middle East respiratory syndrome coronavirus (MERS-CoV). Here, we have carried out comparative viral-human protein-protein interaction and viral protein localization analyses for all three viruses. Subsequent functional genetic screening identified host factors that functionally impinge on coronavirus proliferation, including Tom70, a mitochondrial chaperone protein that interacts with both SARS-CoV-1 and SARS-CoV-2 ORF9b, an interaction we structurally characterized using cryo-electron microscopy. Combining genetically validated host factors with both COVID-19 patient genetic data and medical billing records identified molecular mechanisms and potential drug treatments that merit further molecular and clinical study.

Malignant melanoma is a highly aggressive cutaneous neoplasm with increasing incidence worldwide. Non-SMC condensin II complex suhunit G2 (NCAPG2) exerts import biological function in the pathogenesis of several tumors. In this study, the functional roles of NCAPG2 knockdown in malignant melanoma were revealed in in vitro and in vivo experiments. In vitro study demonstrated that NCAPG2 depletion could inhibit proliferation and migration and promote apoptosis of malignant melanoma cells. Our in vivo date further confirmed that NCAPG2 knockdown attenuated tumor growth of malignant melanoma. Interestingly, NCAPG2 drove tumor development of malignant melanoma through activating the signal transducer and activator of transcription 3 (STAT3). In conclusion, this study elaborated the tumor-promoting effects of NCAPG2 on malignant melanoma, and NCAPG2 may be a potential therapeutic target for malignant melanoma therapy. Key words: malignant melanoma, NCAPG2, cell proliferation, cell apoptosis, STAT3 Le melanome malin est un neoplasme cutane tres agressif dont l'incidence augmente dans le monde entier. La sous-unite G2 du complexe NCAP (NCAPG2) exerce une fonction biologique importante dans la pathogenese de plusieurs tumeurs. Dans cette etude, les roles fonctionnels du knockdown de NCAPG2 dans le melanome malin ont ete reveles dans des experiences in vitro et in vivo. L'etude in vitro a demontre que la depletion de NCAPG2 pouvait inhiber la proliferation et la migration, et promouvoir l'apoptose des cellules de melanome malin. L'etude in vivo a egalement confirme que le knockdown de NCAPG2 diminuait la croissance du melanome malin. II est interessant de noter que NCAPG2 favorisait le developpement tumoral du melanome malin en activant STAT3. En conclusion, cette etude a revele les effets de promotion tumorale de NCAPG2 sur le melanome malin et indique que NCAPG2 peut etre une cible therapeutique potentielle pour la therapie du melanome malin. [Traduit par la Redaction] Mots-cles : melanome malin, NCAPG2, proliferation cellulaire, apoptose, STAT3, Introduction Malignant melanoma is a highly aggressive cutaneous neoplasm with poor prognosis and increasing incidence worldwide (Reinert et al. 2020). Most patients with an early stage malignant melanoma may benefit [...]

Affinity grids have great potential to facilitate rapid preparation of even quite impure samples in single-particle cryo-electron microscopy (EM). Yet despite the promising advances of affinity grids over the past decades, no single strategy has demonstrated general utility. Here we chemically functionalize cryo-EM grids coated with mostly one or two layers of graphene oxide to facilitate affinity capture. The protein of interest is tagged using a system that rapidly forms a highly specific covalent bond to its cognate catcher linked to the grid via a polyethylene glycol (PEG) spacer. Importantly, the spacer keeps particles away from both the air-water interface and the graphene oxide surface, protecting them from potential denaturation and rendering them sufficiently flexible to avoid preferential sample orientation concerns. Furthermore, the PEG spacer successfully reduces nonspecific binding, enabling high-resolution reconstructions from a much cruder lysate sample.

Objective To analyze the sensitivity of common pathogens and common antibiotics in burn and wound repair surgery patients, aiming to provide reference for the prevention and treatment of burn and various wounds. Methods From March 2019 to March 2021, 310 bacterial culture specimens of wound secretion from burn and wound repair surgery patients with suspected wound infection were collected. VITEK 2 Compact automatic bacterial identification instrument and VITEK MS automatic rapid microbial mass spectrometry detection system were used for pathogen identification. Disk diffusion method and instrumental method were employed to detect the antimicrobial susceptibility. The drug resistance of pathogens was analyzed by WHONET 5.6 software. Results Among 310 samples, 179 positive samples were detected, with a positive rate of 57.74%, 84 cases of Gram-positive bacteria, accounting for 46.93%, 91 cases of Gram-negative bacteria, accounting for 50.84% and 4 cases of fungi, accounting for 2.23%. Among them, Gram-negative bacteria were Pseudomonas aeruginosa （PAE）, Acinetobacter baumannii （ABA）, Klebsiella pneumoniae （KPN） and Escherichia coli （ECO）. Staphylococcus aureus （SAU） was the main Gram-positive bacteria. Among the detected Gram-negative bacteria, the sensitivity rate of PAE to polymyxin B, myxin and amikacin was more than 80.40%. The sensitivity rate of ABA to myxin, polymyxin B and tegacyclin exceeded 96.70%. The sensitivity rate of KPN to tegacyclin and polymyxin B antibiotics was higher than 88.90%. The sensitivity rate of ECO to cefotetan, amikacin, piperacillin/tazobactam and carbapenem antibiotics was >92.90%. Among the detected Gram-positive bacteria, the sensitivity of SAU to linezolid, vancomycin and tetracycline was up to 100.00%, and that of Enterococcus to tetracycline, vancomycin and linezolid was also 100.00%. Conclusions Gram-negative bacteria are the main pathogens in patients with wound infection from Department of Burn and Wound Repair Surgery. Antibiotic susceptibility rate of these bacteria were different. Necessary attention should be paid to these pathogens. During the treatment of infection, clinicians should cultivate and prepare bacterial specimens for accurate examination before selecting antibiotics. According to the results of drug sensitivity, they should choose proper antibiotics, and adopt definite treatment instead of empirical medication as early as possible, aiming to inhibit the generation of drug-resistant strains and improve the effectiveness of antibiotic treatment.