亚热带苔藓结皮对土壤-微生物-胞外酶化学计量特征的影响

生物结皮的形成和发育显著影响土壤碳(C)、氮(N)、磷(P)循环及其化学计量特征,土壤微生物如何适应环境资源的化学计量变化仍不明确。本研究以三峡库区苔藓结皮为对象,分析结皮盖度(0、1%～20%、20%～40%、40%～60%、60%～80%和80%～100%)对土壤理化性质(0～5和5～10 cm土层)、微生物生物量和胞外酶活性[(β-1,4-葡萄糖苷酶(BG)、β-1,4-N-乙酰氨基葡萄糖苷酶(NAG)、酸性磷酸酶(AP)]的影响,探索土壤-微生物-胞外酶C∶N∶P化学计量特征间的协变性。结果表明: 生物结皮发育显著提高了土壤黏粒、水稳性团聚体和土壤C、N、P含量,显著降低了土壤容重和砂粒含量;微生物生物量C、N、P和胞外酶活性均随结皮盖度的增大而显著增加;土层深度对土壤理化性质及C∶N∶P均无显著影响,但显著影响微生物生物量、胞外酶活性及BG∶AP和NAG∶AP。相关分析显示,土壤C、N、P含量与微生物生物量和胞外酶活性呈显著正相关,与BG∶NAG呈显著负相关,与NAG∶AP呈显著正相关,但与微生物生物量C∶N∶P无显著相关性;土壤-微生物、微生物-胞外酶C∶N∶P相关性均不显著,BG∶NAG∶AP随着微生物与土壤间C∶N∶P化学计量不平衡性的增加而逐渐降低。表明微生物养分代谢同时受N和P的限制,且P的限制较强烈,微生物可以通过调整自身生物量以及胞外酶C∶N∶P适应生物结皮发育驱动的土壤化学计量变化,从而维持内稳态。     

典型黑土区农田土壤线虫群落的纬度分布格局及其驱动机制

东北黑土区是保障我国粮食安全的重要土壤资源, 了解该区域内农田土壤线虫的群落组成及其对环境驱动因子的响应机制, 对于研究黑土区农田土壤生态系统的生物多样性分布格局具有重要意义。2018年9月, 我们在42°50°‒49°08° N的典型黑土区采集了93个农田土壤样品, 利用形态学鉴定技术分析了土壤线虫群落的组成与结构。共鉴定出47个线虫属(相对丰度 > 1%), 其中食细菌线虫中的拟丽突属(Acrobeloides)是典型黑土区农田土壤中的优势属(相对丰度 > 5%)。土壤线虫总丰富度和总多度均随纬度增加而显著增加, 然而类似的变化趋势只出现在食细菌和杂食/捕食线虫中。土壤有机碳是影响土壤线虫丰富度和多度最为重要的环境因子, 其次是月平均温度。典型黑土区农田土壤线虫群落结构以47° N为分界线分为南部和北部两类, 主要归因于线虫群落中植物寄生和杂食/捕食线虫的相对多度在南、北特征属中存在差异。土壤pH值和容重分别是影响南部与北部黑土区线虫群落最重要的环境因子。本研究明确了典型黑土区农田土壤线虫群落的纬度分布格局及其与环境因素的关系, 可为揭示农业活动干扰下土壤生物对环境因子的响应机制提供基础数据和理论参考。     

昆虫多样性三十年研究进展

当前, 全球昆虫数量和多样性均处于下降趋势, 而导致这一趋势的原因主要包括人为干扰及气候变化。本文基于森林、草地、农业、水生和土壤生态系统, 以植食性、访花、捕食性、寄生性、食果以及食腐昆虫为重点功能昆虫群, 综述了近三十年来国内外昆虫多样性研究领域的主要进展, 并分析了发展趋势。近年来, 昆虫多样性的研究维度不断拓展, 形态多样性研究不断深入, 系统发生多样性、功能多样性和遗传多样性等研究也显著加强。此外, 昆虫多样性研究的空间尺度也逐步扩大, 大尺度区域性研究甚至全球范围的调查持续增长。昆虫进化历史也被引入多样性格局研究中, 并随着系统发生信息学方法的普及而被整合到生态系统建成和生物多样性形成机制研究中。未来需要加强关键昆虫类群整合分类学研究、功能性状多样性、林冠昆虫多样性、互作网络结构等方向的研究。     

心肌缺血再灌注手术改变炎症相关肠道菌群

目的探讨心肌缺血再灌注损伤对大鼠肠道菌群结构特征的影响。方法18只雄性Sprague Dawley大鼠随机分为假手术组(n=7)和模型组(n=11),分别对大鼠冠状动脉左前降支进行结扎和再灌注。再灌注60 min后,通过TTC染色检测总梗死面积,H&E染色和免疫组织化学观察炎症细胞浸润情况、16S rRNA高通量测序分析心肌缺血前和再灌注后粪便中微生物的结构组成变化。结果与假手术组相比,模型组心肌梗死面积增加,心肌中炎症细胞浸润以及CD68阳性巨噬细胞明显增多,变形菌门(Proteobacteria)的相对丰度增加,厚壁菌门(Firmicutes)的相对丰度降低。结论心肌缺血再灌注损伤改变了肠道菌群的分布,这可能与促进了受损心脏的炎症细胞浸润有关。     

竹亚科单枝竹属芸香竹花枝和花特征补充描述

繁殖器官在竹类植物的分类学研究中具有重要意义,研究组在广西马山县观察到竹亚科单枝竹属芸香竹正在开花,该文根据观察到的开花状况和采集到的标本解剖观察结果,对其花枝和繁殖器官特征做了详细的中文及拉丁文补充描述。经对比芸香竹与属内已知繁殖器官结构的单枝竹和小花单枝竹的繁殖器官,3个竹种有相同的繁殖器官结构特征,但在小花数目和大小等方面具有差异。繁殖器官比较表明该属竹种的繁殖器官对喀斯特地貌环境有特殊的适应性,也支持依据营养器官差异划分为3个独立竹种。     

A study of the antibacterial mechanism of pinocembrin against multidrug-resistant Aeromonas hydrophila

International Microbiology - Aeromonas hydrophila is a common pathogen in fish that has caused severe economic losses in aquaculture worldwide. With the emergence of bacterial resistance, it is...     

Genotype distribution and evolutionary analysis of rotavirus associated with acute diarrhea outpatients in Hubei,China, 2013–2016

Group A human rotaviruses (RVAs) annually cause the deaths of 215,000 infants and young children. To understand the epidemiological characteristics and genetic evolution of RVAs, we performed sentinel surveillance on RVA prevalence in a rotavirus-surveillance network in Hubei, China. From 2013 to 2016, a total of 2007 fecal samples from hospital outpatients with acute gastroenteritis were collected from four cities of Hubei Province. Of the 2007 samples, 153 (7.62%) were identified positive for RVA by real-time RT-PCR. RVA infection in Hubei mainly occurred in autumn and winter. The highest detection rate of RVA infection was in 1–2 years old of outpatients (16.97%). No significant difference of RVA positive rate was observed between females and males. We performed a phylogenetic analysis of the G/P genotypes based on the partial VP7/VP4 gene sequences of RVAs. G9P[8] was the most predominant strain in all four years but the prevalence of G2P[4] genotype increased rapidly since 2014. We reconstructed the evolutionary time scale of RVAs in Hubei, and found that the evolutionary rates of the G9, G2, P[8], and P[4] genotypes of RVA were 1.069×10^-3, 1.029×10^-3, 1.283×10^-3 and 1.172×10^-3 nucleotide substitutions/site/year, respectively. Importantly, using a molecular clock model, we showed that most G9, G2, P[8], and P[4] genotype strains dated from the recent ancestor in 2005, 2005, 1993, and 2013, respectively. The finding of the distribution of RVAs in infants and young children in Hubei Province will contribute to the understanding of the epidemiological characteristics and genetic evolution of RVAs in China.     

Neutralization of five SARS-CoV-2 variants of concern by convalescent and BBIBP-CorV vaccinee serum

The prevalence of SARS-CoV-2 variants of concern (VOCs) is still escalating throughout the world. However, the level of neutralization of the inactivated viral vaccine recipients’ sera and convalescent sera against all VOCs, including B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta), and B.1.1.529 (Omicron) remains to be lack of comparative analysis. Therefore, we constructed pseudoviruses of five VOCs using a lentiviral-based system and analyzed their viral infectivity and neutralization resistance to convalescent and BBIBP-CorV vaccinee serum at different times. Our results show that, compared with the wild-type strain (WT), five VOC pseudoviruses showed higher infection, of which B.1.617.2 and B.1.1.529 variant pseudoviruses exhibited higher infection rates than wild-type or other VOC strains, respectively. Sera from 10 vaccinated individuals at the 1, 3 and 5-month post second dose or from 10 convalescent at 14 and 200 days after discharge retained neutralizing activity against all strains but exhibited decreased neutralization activity significantly against the five VOC variant pseudoviruses over time compared to WT. Notably, 100% (30/30) of the vaccinee serum samples showed more than a 2.5-fold reduction in neutralizing activity against B.1.1.529, and 90% (18/20) of the convalescent serum samples showed more than 2.5-fold reduction in neutralization against B.1.1.529. These findings demonstrate the reduced protection against the VOCs in vaccinated and convalescent individuals over time, indicating that it is necessary to have a booster shot and develop new vaccines capable of eliciting broad neutralization antibodies.     

Infection and pathogenesis of the Delta variant of SARS-CoV-2 in Rhesus macaque

Highlights
1. Delta variant of SARS-CoV-2 can effectively infect the Rhesus macaque.
2. The Delta variant grows faster than the early strain isolated from Wuhan in late 2019.
3. The shedding pattern, viral load and disease severity of Delta variant are similar with the early strain isolated from Wuhan in late 2019.
4. This study supports the attributed rapid disease spread of the Delta variant.     

Generation and functional characterisation of Plasmodium yoelii csp deletion mutants using a microhomology-based CRISPR/Cas9 method

CRISPR/Cas9 is a powerful genome editing method that has greatly facilitated functional studies in many eukaryotic organisms including malaria parasites. Due to the lack of genes encoding enzymes necessary for the non-homologous end joining DNA repair pathway, genetic manipulation of malaria parasite genomes is generally accomplished through homologous recombination requiring the presence of DNA templates. Recently, an alternative double-strand break repair pathway, microhomology-mediated end joining, was found in the Plasmodium falciparum parasite. Taking advantage of the MMEJ pathway, we developed a MMEJ-based CRISPR/Cas9 (mCRISPR) strategy to efficiently generate multiple mutant parasites simultaneously in genes with repetitive sequences. As a proof of principle, we successfully produced various size mutants in the central repeat region of the Plasmodium yoelii circumsporozoite surface protein without the use of template DNA. Monitoring mixed parasite populations and individual parasites with different sizes of CSP-CRR showed that the CSP-CRR plays a role in the development of mosquito stages, with severe developmental defects in parasites with large deletions in the repeat region. However, the majority of the csp mutant parasite clones grew similarly to the wild type P. yoelii 17XL parasite in mice. This study develops a useful technique to efficiently generate mutant parasites with deletions or insertions, and shows that the CSP-CRR plays a role in parasite development in mosquito.