Drivers of Collembola assemblages along an altitudinal gradient in northeast China

Altitudinal changes in the diversity of plants and animals have been well documented; however, soil animals received little attention in this context and it is unclear whether their diversity follows general altitudinal distribution patterns. Changbai Mountain is one of few well‐conserved mountain regions comprising natural ecosystems on the Eurasian continent. Here, we present a comprehensive analysis of the diversity and community composition of Collembola along ten altitudinal sites representing five vegetation types from forest to alpine tundra. Among 7834 Collembola individuals, 84 morphospecies were identified. Species richness varied marginally significant with altitude and generally followed a unimodal relationship with altitude. By contrast, the density of Collembola did not change in a consistent way with altitude. Collembola communities changed gradually with altitude, with local habitat‐related factors (soil and litter carbon‐to‐nitrogen ratio, litter carbon content, and soil pH) and climatic variables (precipitation seasonality) identified as major drivers of changes in Collembola community composition. Notably, local habitat‐related factors explained more variation in Collembola assemblages than climatic variables. The results suggest that local habitat‐related factors including precipitation and temperature are the main drivers of changes in Collembola communities with altitude. Specifically, soil and litter carbon‐to‐nitrogen ratio correlated positively with Collembola communities at high altitudes, whereas soil pH correlated positively at low altitudes. This documents that altitudinal gradients provide unique opportunities for identifying factors driving the community composition of not only above‐ but also belowground invertebrates.     

A lethal model of Leptospira infection in hamster nasal mucosa

Leptospirosis is a fatal zoonosis caused by contact between skin or a mucosal surface and contaminated soil or water. Hamsters were infected by intraperitoneal injection fto establish experimental leptospirosis, which is not a natural route of infection. There are no reports of nasal mucosal infection in hamsters. In this study, infection of the nasal mucosa was performed to establish a model of natural infection. Both methods of infection can cause lethal models with similar symptoms in the later stages of infection, such as weight loss, blood concentration, increased neutrophils (GRAN), and decreased lymphocytes (LYM) in the blood, severe organ damage and liver function obstruction. The burden of Leptospira in the organs and blood was lower in the mucosal inoculation groups at 1 day after infection. However, mucosal infection induced a higher Leptospira burden in urine than intraperitoneal infection in the late stages of infection. After nasal mucosal infection, antibody levels were higher and lasted longer. These results indicated that the route of nasal mucosal infection is a good choice for studying leptospirosis in hamsters.     

A circular intronic RNA ciPVT1 delays endothelial cell senescence by regulating the miR‐24‐3p/CDK4/pRb axis

Circular RNAs (circRNAs) have been established to be involved in numerous processes in the human genome, but their function in vascular aging remains largely unknown. In this study, we aimed to characterize and analyze the function of a circular intronic RNA, ciPVT1, in endothelial cell senescence. We observed significant downregulation of ciPVT1 in senescent endothelial cells. In proliferating endothelial cells, ciPVT1 knockdown induced a premature senescence‐like phenotype, inhibited proliferation, and led to an impairment in angiogenesis. An in vivo angiogenic plug assay revealed that ciPVT1 silencing significantly inhibited endothelial tube formation and decreased hemoglobin content. Conversely, overexpression of ciPVT1 in old endothelial cells delayed senescence, promoted proliferation, and increased angiogenic activity. Mechanistic studies revealed that ciPVT1 can sponge miR‐24‐3p to upregulate the expression of CDK4, resulting in enhanced Rb phosphorylation. Moreover, enforced expression of ciPVT1 reversed the senescence induction effect of miR‐24‐3p in endothelial cells. In summary, the present study reveals a pivotal role for ciPVT1 in regulating endothelial cell senescence and may have important implications in the search of strategies to counteract the development of age‐associated vascular pathologies.     

DNA-free CRISPR-Cas9 gene editing of wild tetraploid tomato Solanum peruvianum using protoplast regeneration

Wild tomatoes (Solanum peruvianum) are important genomic resources for tomato research and breeding. Development of a foreign DNA-free clustered regularly interspaced short palindromic repeat (CRISPR)-Cas delivery system has potential to mitigate public concern about genetically modified organisms. Here, we established a DNA-free CRISPR-Cas9 genome editing system based on an optimized protoplast regeneration protocol of S. peruvianum, an important resource for tomato introgression breeding. We generated mutants for genes involved in small interfering RNAs biogenesis, RNA-DEPENDENT RNA POLYMERASE 6 (SpRDR6), and SUPPRESSOR OF GENE SILENCING 3 (SpSGS3); pathogen-related peptide precursors, PATHOGENESIS-RELATED PROTEIN-1 (SpPR-1) and PROSYSTEMIN (SpProSys); and fungal resistance (MILDEW RESISTANT LOCUS O, SpMlo1) using diploid or tetraploid protoplasts derived from in vitro-grown shoots. The ploidy level of these regenerants was not affected by PEG-Ca²⁺-mediated transfection, CRISPR reagents, or the target genes. By karyotyping and whole genome sequencing analysis, we confirmed that CRISPR-Cas9 editing did not introduce chromosomal changes or unintended genome editing sites. All mutated genes in both diploid and tetraploid regenerants were heritable in the next generation. spsgs3 null T₀ regenerants and sprdr6 null T₁ progeny had wiry, sterile phenotypes in both diploid and tetraploid lines. The sterility of the spsgs3 null mutant was partially rescued, and fruits were obtained by grafting to wild-type (WT) stock and pollination with WT pollen. The resulting seeds contained the mutated alleles. Tomato yellow leaf curl virus proliferated at higher levels in spsgs3 and sprdr6 mutants than in the WT. Therefore, this protoplast regeneration technique should greatly facilitate tomato polyploidization and enable the use of CRISPR-Cas for S. peruvianum domestication and tomato breeding.

A DNA-free CRISPR-Cas9 genome editing tool based on an optimized protoplast regeneration protocol of wild tomato creates stable and inheritable diploid and tetraploid regenerants.     

编辑MSTN半胱氨酸节基元促进两广小花猪肌肉生长

肌生长抑制素(myostatin,MSTN)是转化生长因子 β(transforming growth factor-β,TGF-β)家族成员之一,是一种肌肉生长抑制因子.解除MSTN的生长抑制功能是提高畜禽肌肉产量的一种有效途径.TGF-β 的半胱氨酸节结构基元(cystine knot motif)能够稳定MSTN...