Electronic and Steric Control of Rates and Selectivities in Rhodium-Catalyzed [2+2+2] Cycloadditions for Constructing Fused Tricyclic Hydronaphthofurans: A Density Functional Theory Study.

Fused tricyclic hydronaphthofurans with multiple chiral centers are very important skeletons for constructing natural products; however, their synthesis is challenging, and a detailed understanding of the final formation mechanism remains elusive. In this work, density functional theory computations were employed to characterize rhodium-catalyzed [2+2+2] cycloaddition of enyne with terminal alkynes. The putative mechanism involves an initial ligand exchange, followed by oxidative cyclization, olefin insertion, and reductive elimination processes. Oxidative cyclization is shown to be the rate- and selectivity-determining step of the full chemical transformation, where the R substituent on terminal alkynes has a significant influence on the reaction selectivities. When R is an electron-donating group (OMe and Me), the ortho-substituted tricyclic hydronaphthofurans (P1) are predicted to be dominant; on the contrary, meta-substituted compounds P2 emerge as the main products when R is an electron-withdrawing group (NO2, CF3, and CN). Computational predictions for selectivity are in good agreement with experimental product ratios. Free energy barriers of the rate-determining step for P1 and P2 are ∼22.3-23.6 kcal mol-1, which align well with their experimental yields of ∼79-92% at 313 K after 0.5 h. The results also accurately reproduce experimentally observed regio-, chemo-, and enantioselectivities, with steric hindrance as well as electronic properties of the substrate and ligand markedly influencing the reaction rates and selectivities. The influence of computational methods is also explored and discussed in detail.

PD-1+CXCR5-CD4+ Th-CXCL13 cell subset drives B cells into tertiary lymphoid structures of nasopharyngeal carcinoma.

BACKGROUND: A major current challenge is to exploit tertiary lymphoid structures (TLSs) to promote the lymphocyte infiltration, activation and differentiation by tumor antigens to increase antitumor immune responses. The mechanisms that underlie the role of TLS formation in the adaptive immune responses against nasopharyngeal carcinoma (NPC) remain largely unknown. METHODS: Cell populations and the corresponding markers were identified by single-cell RNA sequencing and fluorescence-activated cell sorting analysis. In vitro differentiation experiments were used to simulate the generation, regulation and function of the Th-CXCL13 cell subset in the tumor microenvironment of NPC. These were followed by histological evaluation of the colocalization of tumor-associated B cells (TABs) and Th-CXCL13 cells within TLSs, and statistical analysis of the relationship between the cells in TLSs and overall survival. RESULTS: A PD-1+CXCR5-CD4+ Th-CXCL13 cell subset was identified in NPC. This subset was a major source of CXCL13, representing the majority of the CD4+ T cells at levels comparable with Th1 and Tfh cells present in the TLSs. Monocytes activated by toll-like receptor 4 agonists served as the antigen-presenting cells that most efficiently triggered the expansion of Th-CXCL13 cells. Transforming growth factor beta 1 (TGF-ß1) stimulation and activation of Sox4 were critical for the induction and polarization of Th-CXCL13 cells in this process. The potential functional contributions of TABs recruited by Th-CXCL13 cells which induced plasma cell differentiation and immunoglobulin production via interleukin-21 and CD84 interactions in the TLSs demonstrated improved survival. CONCLUSIONS: Induction of Th-CXCL13 cells links innate inflammation to immune privilege in tumor-associated TLSs and might predict better survival.

Immunization with a Self-Assembled Nanoparticle Vaccine Elicits Potent Neutralizing Antibody Responses against EBV Infection.

Epstein-Barr virus (EBV) infection is a global health concern infecting over 90% of the population. However, there is no currently available vaccine. EBV primarily infects B cells, where the major glycoprotein 350 (gp350) is the main target of neutralizing antibodies. Given the advancement of nanoparticle vaccines, we describe rationally designed vaccine modalities presenting 60 copies of gp350 on self-assembled nanoparticles in a repetitive array. In a mouse model, gp350s on lumazine synthase (LS) and I3-01 adjuvanted with MF59 or aluminum hydroxide (Alhydrogel) elicited over 65- to 133-fold higher neutralizing antibody titers than the corresponding gp350 monomer to EBV. Furthermore, immunization with gp350D123-LS and gp350D123-I3-01 vaccine induced a Th2-biased response. For the nonhuman primate model, gp350D123-LS in MF59 elicited higher titers of total IgG and neutralizing antibodies than the monomeric gp350D123. Overall, these results support gp350D123-based nanoparticle vaccine design as a promising vaccine candidate for potent protection against EBV infection.

Rapid Development of SARS-CoV-2 Spike Protein Receptor-Binding Domain Self-Assembled Nanoparticle Vaccine Candidates.

The coronavirus disease pandemic of 2019 (COVID-19) caused by the novel SARS-CoV-2 coronavirus resulted in economic losses and threatened human health worldwide. The pandemic highlights an urgent need for a stable, easily produced, and effective vaccine. SARS-CoV-2 uses the spike protein receptor-binding domain (RBD) to bind its cognate receptor, angiotensin-converting enzyme 2 (ACE2), and initiate membrane fusion. Thus, the RBD is an ideal target for vaccine development. In this study, we designed three different RBD-conjugated nanoparticle vaccine candidates, namely, RBD-Ferritin (24-mer), RBD-mi3 (60-mer), and RBD-I53-50 (120-mer), via covalent conjugation using the SpyTag-SpyCatcher system. When mice were immunized with the RBD-conjugated nanoparticles (NPs) in conjunction with the AddaVax or Sigma Adjuvant System, the resulting antisera exhibited 8- to 120-fold greater neutralizing activity against both a pseudovirus and the authentic virus than those of mice immunized with monomeric RBD. Most importantly, sera from mice immunized with RBD-conjugated NPs more efficiently blocked the binding of RBD to ACE2 in vitro, further corroborating the promising immunization effect. Additionally, the vaccine has distinct advantages in terms of a relatively simple scale-up and flexible assembly. These results illustrate that the SARS-CoV-2 RBD-conjugated nanoparticles developed in this study are a competitive vaccine candidate and that the carrier nanoparticles could be adopted as a universal platform for a future vaccine development.

Single-cell transcriptomic analysis defines the interplay between tumor cells, viral infection, and the microenvironment in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated malignancy with a complex tumor ecosystem. How the interplay between tumor cells, EBV, and the microenvironment contributes to NPC progression and immune evasion remains unclear. Here we performed single-cell RNA sequencing on ~104,000 cells from 19 EBV+ NPCs and 7 nonmalignant nasopharyngeal biopsies, simultaneously profiling the transcriptomes of malignant cells, EBV, stromal and immune cells. Overall, we identified global upregulation of interferon responses in the multicellular ecosystem of NPC. Notably, an epithelial-immune dual feature of malignant cells was discovered and associated with poor prognosis. Functional experiments revealed that tumor cells with this dual feature exhibited a higher capacity for tumorigenesis. Further characterization of the cellular components of the tumor microenvironment (TME) and their interactions with tumor cells revealed that the dual feature of tumor cells was positively correlated with the expression of co-inhibitory receptors on CD8+ tumor-infiltrating T cells. In addition, tumor cells with the dual feature were found to repress IFN-γ production by T cells, demonstrating their capacity for immune suppression. Our results provide new insights into the multicellular ecosystem of NPC and offer important clinical implications.

Complete chloroplast genome of a rare deciduous tree species, Sinomanglietia glauca (Magnoliaceae).

The complete chloroplast genome of a rare deciduous tree species with ornamental value, Sinomanglietia glauca, was first determined. It was 160,170 bp in length, including a pair of inverted repeat (IR, 26,567 bp) regions separated by a small single copy (SSC, 18,842 bp) sequence and a large single copy (LSC, 88,194 bp) sequence. The chloroplast genome contained 132 genes, consisting of 87 CDS, 8 rRNA genes, and 37 tRNA genes. Thirty-four SSR sites were detected in the chloroplast genome. The phylogenetic analysis revealed that all sampled Manglietia species were clustered together, and S. glauca was placed as sister to the clade Manglietia, indicated that the genus Sinomanglietia may be legitimate and should be recovered.

Two plastomes of Phyllostachys and reconstruction of phylogenic relationship amongst selected Phyllostachys species using genome skimming.

The genus Phyllostachys is economically important; however, only a small amount of complete plastid genomes have been reported to date. Here, we characterized two complete chloroplast genomes of Phyllostachys using genome skimming. The chloroplast genomes of Phyllostachys reticulata and Phyllostachys edulis 'Pachyloen' were 136,689 bp and 139,678 bp in length, respectively, and their GC contents were 38.8% and 38.9%, respectively. The sequences of each species contained 132 unique genes, including 39 tRNA, eight rRNA, and 85 protein-coding genes. Phylogenetic analysis shows that all selected Phyllostachys species were grouped into one well-supported clade in the Phyllostachys clade (V) of Arundinarieae. Moreover, in terms of chloroplast genome size, structure, and composition, P. edulis 'Pachyloen' is identical to P. edulis, further indicating the affinity between them.

[Distribution of biogenic organic dimethylated sulfur compounds and its influencing factors in the east China Sea in summer].

Dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) are the most important biogenic organic dimethylated sulfur compounds in the ocean. The spatial distributions of these three sulfur compounds and their influencing factors were investigated in the East China Sea in June 2013. The mean concentrations of DMS, DMSPd, DMSPp, DMSOd and DMSOp in the surface seawater were 4.70, 7.00, 27.83, 13.66 and 10.78 nmol x L(-1), respectively. The horizontal distributions of DMS, DMSP and DMSO exhibited the similar patterns to that of chlorophyll a (Chl-a), with high values in coastal regions and low values in the open sea. DMS, DMSPd and DMSOp concentrations were significantly correlated with the levels of Chl-a, indicating that phytoplankton biomass might play an important role in controlling the concentrations of these sulfur compounds in the East China Sea. Moreover, positive relationships were observed between DMS and DMSPd and between DMSOd and DMS in the study area, which implied that the microbial degradation of DMSPd was the main source of DMS and DMSOd came mostly from the oxidation of DMS. The sea-to-air flux of DMS from the East China Sea in summer ranged from 0.62 to 33.98 micromol x (m2 x d)(-1), with an average of 9.71 micromol x (m2 x d)(-1).

[Teratogenicity of 3, 4 two furazan-based oxidation furazan in rats].

OBJECTIVE: To study the teratogenicity of new high-energy compounds, 3, 4 two furazan-based oxidation furazan (DNTF) and the impact on human health, occupational exposure limits were provided for the following research. METHODS: Pregnant SD rats were randomly divided into five groups by Standard teratogenicity test, including three dose groups (5.0, 15.8, 50.0 mg/kg), the negative control (vegetable oil), and the positive control group (CP 10.0 mg/kg). Each 10 to 15 rats were in one group. Gavage was consecutive for rats during pregnancy 7 ∼ 12 d and then sacrifice after 20 d. RESULTS: There were no significantly difference between the three dose groups and negative controls in the pregnancy rate, the weight of pregnant rats, fetal weight, fetal growth, fetal malformation rate and internal organs, CONCLUSION: There were no maternal toxicity, embryo toxicity and teratogenicity for rats when DNTF in the range 5.0 ∼ 50.0 mg/kg.