Tianli Zheng

Signal recognition particle (SRP) pathway function in protein translocation across the endoplasmic reticulum (ER) is well established; its role in RNA localization to the ER remains, however, unclear. In current models, mRNAs undergo translation- and SRP-dependent trafficking to the ER, with ER localization mediated via interactions between SRP-bound translating ribosomes and the ER-resident SRP receptor (SR), a heterodimeric complex comprising SRA, the SRP-binding subunit, and SRB, an integral membrane ER protein. To study SRP pathway function in RNA localization, SR knockout (KO) mammalian cell lines were generated and the consequences of SR KO on steady-state and dynamic mRNA localization examined. CRISPR/Cas9-mediatedSRPRBKO resulted in profound destabilization of SRA. Pairing siRNA silencing ofSRPRAinSRPRBKO cells yielded viable SR KO cells. Steady-state mRNA compositions and ER-localization patterns in parental and SR KO cells were determined by cell fractionation and deep sequencing. Notably, steady-state cytosol and ER mRNA compositions and partitioning patterns were largely unaltered by loss of SR expression. To examine SRP pathway function in RNA localization dynamics, the subcellular trafficking itineraries of newly exported mRNAs were determined by 4-thiouridine (4SU) pulse-labeling/4SU-seq/cell fractionation. Newly exported mRNAs were distinguished by high ER enrichment, with ER localization being SR-independent. Intriguingly, under conditions of translation initiation inhibition, the ER was the default localization site for all newly exported mRNAs. These data demonstrate that mRNA localization to the ER can be uncoupled from the SRP pathway function and reopen questions regarding the mechanism of RNA localization to the ER.

To investigate the status of infections caused by respiratory pathogens and the patterns of infections caused by pathogens in different seasons, age groups and stages of pneumoconiosis so as to explore the pathogen spectrum of respiratory tract infections in pneumoconiosis patients. The sputum samples of 376 pneumoconiosis patients admitted to an occupational disease hospital in Chengdu between January, 2017 and October, 2019 were collected. Clinical information of the patients was collected and lab tests were conducted to check for 23 kinds of common respiratory viruses, bacteria and fungi in the sputum. The relationship between seasons, ages, and different stages of pneumoconiosis and the pathogen detection rate was analyzed. In the 376 sputum samples, the detection rates of pathogens, viruses, bacteria and fungi were 42.29% (159/376), 32.98% (124/376), 9.57% (36/376) and 6.12% (23/376), respectively. The six pathogens with the highest detection rates were parainfluenza virus, rhinovirus, influenza virus, Candida albicans, Klebsiella pneumoniae and Candida krousei. The severity of respiratory tract infection did not show significant difference in different seasons, age groups, and pneumoconiosis stages. The pathogen spectrum of respiratory tract infections in patients with pneumoconiosis is complicated and the proportion of viral infection is high. However, the severity of the infection is not associated with age, seasonal, or pneumoconiosis staging differences.

Tourists are the main users of the park, whose spatial and temporal distribution and behavioral characteristics are the most real reflection of the construction of the park environment. Tourists in Beihai Park were selected as the research object. Through field investigation and interview investigation, the main behavior characteristics of tourists in different time and space in winter were studied. Finally, from the perspectives of tourists relation with time and space, we analyze the existing problems, understand the causes of these phenomena, and then put forward the corresponding countermeasures and suggestions, and make suggestions on the construction and management of such parks.

Protein synthesis on the endoplasmic reticulum (ER) requires the dynamic coordination of resident membrane proteins and cytoplasmic translation factors. While ER membrane proteins functioning in ribosome association, mRNA anchoring, and protein translocation, have been identified, little is known regarding the higher order organization of ER-localized translation. Here we utilized proximity proteomics to identify neighboring protein networks for the ribosome interactors SEC61β, RPN1, SEC62, and LRRC59. Whereas the SEC61β and RPN1 BioID reporters revealed translocon-associated networks, the SEC62 and LRRC59 reporters identified divergent interactome networks of previously unexplored functions. Notably, the SEC62 interactome is enriched in redox-linked proteins and ER luminal chaperones, whereas the LRRC59 interactome is enriched in SRP pathway components, translation factors, and ER-localized RNA-binding proteins. Analysis of the LRRC59 interactome by native immunoprecipitation identified similar protein and functional enrichments. Combined, these data reveal a functional domain organization for the ER and suggest a key role for LRRC59 in the organization of mRNA translation on the ER. Summary: Hannigan et al. characterize the protein interactomes of four ER ribosome-binding proteins, providing evidence that ER-bound ribosomes reside in distinct molecular environments. Their data link SEC62 to ER redox regulation and chaperone trafficking, and suggest a role for LRRC59 in SRP-coupled protein synthesis.

Soil respiration is one of the most important components in the carbon (C) cycle in terrestrial ecosystems. To investigate the contribution of each component of C cycle to the total soil C efflux, we quantified the rates of litter, root, and other mineral soil respiration from 2012 to 2014 in the primary and secondary tropical mountain rain forests in Hainan Island, China. The seasonal dynamics of soil (R_s), non-litter (R_NL) and non-root (R_NR) respiration rates were measured using an automatic chamber system (Li-8100). Litter removal and root removal treatments were used to assess the contribution of litter and roots to belowground C production. We estimated the annual C efflux of each component of soil respiration in primary and secondary forests using a temperature-based exponential model and analyzed the impact of each component in each forest type. The annual total soil C efflux was significantly higher in the primary rain forest (1567±205g C m⁻² yr⁻¹) than that in the secondary forest (1300±70g C m⁻² yr⁻¹, P < 0.05). The litter, root, and mineral soils contributed 22% (349±185g C m⁻² yr⁻¹), 38% (589±100g C m⁻² yr⁻¹), and 40% (628±128g C m⁻² yr⁻¹) to the total soil C efflux in primary rain forest, respectively. In secondary forest, these three components contributed 11% (148±35g C m⁻² yr⁻¹), 45% (572±259g C m⁻² yr⁻¹), and 44% (580±226g C m⁻² yr⁻¹), respectively. The temperature sensitivity (Q₁₀) of R_s (2.70±0.14) in the primary forest was significantly higher than that in the secondary forest (2.34±0.12), with the Q₁₀ values for respiration decreasing in the order of R_NR > R_s > R_NL. These results show that the difference in litter respiration between primary and secondary forest caused the major difference in annual soil respiration efflux between these two forest types. In addition, the litter respiration is more sensitive to the soil temperature than the other soil respiration components.

Human respiratory syncytial virus (HRSV) is a major pathogen that causes worldwide seasonal epidemic disease in infants due to its genetic variations. However, published information on the molecular epidemiology of HRSV was never reported particularly in Chengdu of West China. During five consecutive seasons (from 2009 to 2014), 433 (23.7%) of 1827 samples from hospitalized patients were identified as HRSV positive. Epidemiological characteristics of HRSV revealed that subtype A viruses (62.7%) prevailed in the first three epidemic seasons and faded in the next two seasons, while subtype B viruses (37.3%) kept circulating in five epidemic periods. According to the phylogenetic analysis of glycoprotein (G) gene, five HRSV genotypes NA1, ON1, BA9, BA‐C, and CB1 were found in Chengdu. The predominant circulating genotype changed from NA1 in the period of 2010–2012 to BA9 of 2013–2014. The newly emerging ON1 was first reported in West China in October 2013. The early genotypes BA‐C and CB1 were replaced by the prevailing BA9 after the third epidemic peak. Genetic mutations in glycosylation sites of G protein were found in HRSV variants, suggesting the virus is able to escape the immune recognition and attack. This study elucidated the local HRSV epidemic was associated with the alternate circulation of multiple genotypes and with the change of glycosylation sites of G protein. J. Med. Virol. 89:32–40, 2017.

The mRNA transcriptome is currently thought to be partitioned between the cytosol and endoplasmic reticulum (ER) compartments by binary selection; mRNAs encoding cytosolic/nucleoplasmic proteins are translated on free ribosomes, and mRNAs encoding topogenic signal-bearing proteins are translated on ER-bound ribosomes, with ER localization being conferred by the signal-recognition particle pathway. In subgenomic and genomic analyses of subcellular mRNA partitioning, we report an overlapping subcellular distribution of cytosolic/nucleoplasmic and topogenic signal-encoding mRNAs, with mRNAs of both cohorts displaying noncanonical subcellular partitioning patterns. Unexpectedly, the topogenic signal-encoding mRNA transcriptome was observed to partition in a hierarchical, cohort-specific manner. mRNAs encoding resident proteins of the endomembrane system were clustered at high ER-enrichment values, whereas mRNAs encoding secretory pathway cargo were broadly represented on free and ER-bound ribosomes. Two distinct modes of mRNA association with the ER were identified. mRNAs encoding endomembrane-resident proteins were bound via direct, ribosome-independent interactions, whereas mRNAs encoding secretory cargo displayed predominantly ribosome-dependent modes of ER association. These data indicate that mRNAs are partitioned between the cytosol and ER compartments via a hierarchical system of intrinsic and encoded topogenic signals and identify mRNA cohort-restricted modes of mRNA association with the ER.