Active predation,phylogenetic diversity,and global prevalence of myxobacteria in wastewater treatment plants

The operation of modern wastewater treatment plants (WWTPs) is driven by activated sludge microbiota, a complex assemblage of trophically interacting microorganisms. Microbial predation is crucial to fundamental understanding of how biological interactions drive microbiome structuring and functioning of WWTPs. However, predatory bacteria have received little attention regarding their diversity, activity, and ecological function in activated sludge, limiting the exploitation of food web interactions for wastewater microbiome engineering. Here, by using rRNA-stable isotope probing of activated sludge microbiota with ¹³C-labeled prey bacteria, we uncovered diverse as-yet-uncultivated putative predatory bacteria that actively incorporated ¹³C-biomass. Myxobacteria, especially Haliangium and the mle1-27 clade, were found as the dominant active predators, refreshing conventional views based on a few predatory isolates of Bdellovibrionota from WWTPs. The identified predatory bacteria showed more selective predation on prey compared with the protists dominated by ciliates, providing in situ evidence for inter-domain predation behavior divergence in activated sludge. Putative predatory bacteria were tracked over a two-year microbiome monitoring effort at a local WWTP, revealing the predominance of Myxococcota (6.5 ± 1.3%) over Bdellovibrionota (1.0 ± 0.2%) lineages. Phylogenetic analysis unveiled highly diverse myxobacteria inhabiting activated sludge and suggested a habitat filtering effect in global WWTPs. Further mining of a global activated sludge microbiome dataset revealed the prevalence of Myxococcota (5.4 ± 0.1%) species and potential impacts of myxobacterial predation on process performance. Collectively, our findings provided unique insights into the predating activity, diversity, and prevalence of Myxococcota species in activated sludge, highlighting their links with wastewater treatment processes via trophic regulation of enteric and functional bacteria.Subject terms: Microbial ecology, Biodiversity, Environmental microbiology, Microbial ecology, Environmental sciences     

异质水分环境下野牛草相连分株间光合同化物的生理整合及其调控

异质环境下,克隆植物通过生理整合机制使资源在分株间实现共享,提高了其对异质性环境的适应能力,具有重要的生态进化意义,研究生理整合机制及其调控机理可为进一步发掘克隆植物应用潜力提供理论依据。以野牛草3个相连分株为材料,对其中一个分株用30%聚乙二醇6000(PEG-6000)模拟水分胁迫,通过Hoagland营养液培养试验,研究了异质水分环境下光合同化物在野牛草相连分株间的生理整合及分株叶片与根系内源激素ABA与IAA含量的变化规律。结果表明,14C-光合同化物在克隆片断内存在双向运输,但以向顶运输为主,异质水分环境下,受胁迫分株光合同化物的输出率明显降低,而与其相邻分株合成的光合同化物向受胁迫分株方向运输率明显增加;异质水分环境下,各分株ABA含量均明显增加,但以受胁迫的分株叶片及根系ABA的含量增加幅度最大,各分株IAA含量较对照均显著下降(P0.05),且以受胁迫分株IAA含量下降幅度最大;各分株叶片与根系ABA/IAA均显著提高(P0.05),相邻分株ABA/IAA增加幅度低于受胁迫分株。异质水分环境影响野牛草克隆分株间光合同化物的生理整合,且ABA与IAA在分株间光合同化物运输与分配过程中具有重要的调节作用。     

代谢组学及其在环境毒理学中的应用

代谢组学作为系统生物学的一部分,因其具有分析速度快的特点,被广泛用于生物医学等方面的研究。目前代谢组学在环境毒理学方面的研究主要针对单一污染物,但也需要考虑到被污染地的复杂情况。通过介绍代谢组学及其发展历程,总结了目前主流代谢组学技术的各自特点,讨论了代谢组学在环境重金属、有机污染物和抗生素中的毒性评估以及环境胁迫耐受性中的评价等方面内容,综述了其在环境毒理学中的应用,并指出其应用不足,旨在为代谢组学应用于环境毒理学的研究提供参考。     

肺炎克雷伯氏菌VBNC状态转化突变株的筛选与特性研究

采用双亲本接合法对从文山湖富营养化水体中分离得到肺炎克雷伯氏菌进行Tn5转座子插入诱变,在含四环素和卡那霉素的LB培养基上获得接合子,利用饥饿冷冻高渗透压法对接合子进行细菌VBNC状态转化突变株的筛选和特性的研究。结果表明,带有卡那霉素基因的Tn5成功地插入到了肺炎克雷伯氏菌的染色体中,在双抗性培养基上获得约2.3×104 cell/mL的接合子,转座效率为6.58×10-4。对多个接合子和对照肺炎克雷伯氏菌的诱导、筛选及比较,发现KPQT-7是最快进入VBNC状态的突变株,该突变株在胁迫诱导9d后超过30%的细胞都进入了VBNC状态,而对照的肺炎克雷伯氏菌至少要在诱导21d后才大部分进入VBNC状态。在此基础上,对VBNC转化突变株KPQT-7作进一步的遗传学分析将会为细菌VBNC状态分子机理的研究奠定坚实的基础。     

Proteomics Analysis of Antitumor Activity of Agrimonia pilosa Ledeb. in Human Oral Squamous Cell Carcinoma Cells

Oral cancer is a malignant neoplasm of oral cavity. It accounts for approximately 5% of all malignant tumors. Approximately 97% of all oral cancers are squamous cell carcinomas, followed by adenocarcinomas, and rarely malignant melanomas. It occurs particularly in males (twice as common in males than in females) of middle age (above 40 years). Agrimonia pilosa Ledeb. has traditionally been known for its effective antitumor activity and is currently used in China for cancer therapy. A. pilosa Ledeb. has been traditionally used for the treatment of abdominal pain, sore throat, headache, blood discharge, parasitic infections, and eczema in Korea and other Asian countries. Most studies on A. pilosa Ledeb. are related to the leaves and a few investigated the roots of the plant. However, detailed mechanisms of antitumor activity of A. pilosa Ledeb. have not been fully elucidated. Furthermore, to date, there have been no reports on the antitumor effect of A. pilosa Ledeb. in oral squamous cells. In this study, we used proteomic technology to observe changes in proteins related to anticancer activity of A. pilosa Ledeb. and identified target proteins among altered proteins to reveal the underlying mechanism of action.     

细胞老化的基本特征和研究进展

自20世纪60年代初发现细胞老化以来,关于细胞老化的研究有了长足的进展。"Hay-flick极限(Hayflick limit)"概念的确立不仅在细胞水平揭示了细胞寿命的重要分子机制,而且拓展了人们对于衰老(aging)的认识。近年来,越来越多的实验结果表明,细胞老化可以在体内有效阻止癌症的发生,尤其在癌症早期具有明显作用。该文就半个多世纪以来,关于人们认知的细胞老化的基本特征、判别标准以及相关研究进展予以综述。     

白背飞虱的迁飞生物学:江苏苏州个例分析

对苏州市吴中区1984—2002年灯诱数据的分析表明,白背飞虱Sogatella furcifera(Horváth)的灯下始见期一般在6月上旬,而主迁峰日则一般出现在7月上旬。1996年后,始见期有提前的趋势。对18年灯诱虫量的时间序列分析表明,田间迁入代虫量与6月份的灯诱虫量相关,田间第1代虫量与迁入代虫量相关,第2代则只与田间第1代和8月份的诱虫量相关。对1986—2002年吴中区白背飞虱田间虫量的分析表明,白背飞虱在田间一般要完成2个世代,20世纪90年代中期之后会出现第3代,表现出低迁入率(平均百穴21头)、高增殖倍数(G1/G0在30～200倍左右)和高峰值密度(16年平均百穴3200头)的种群特征。此间白背飞虱长翅型成虫的比率不高,迁入后便像褐飞虱Nilaparvata lugens(Stl)那样形成了滞留本地的增殖代(7月20日到8月10日)和以本地滞留为害与部分迁出个体混合而成的主害代(8月15日到9月5日),直到8月下旬和9月上中旬,其长翅型比率才会有大幅回升开始回迁,呈现出翅型长-短-长的变化模式。     

A Modest Protective Effect of Thyrotropin against Bone Loss Is Associated with Plasma Triiodothyronine Levels

Background

The independent skeletal effect of thyrotropin (thyroid stimulating hormone, TSH) has been suggested in animal studies. However, clinical data on the association between bone loss and variations in TSH levels is inconsistent. This study aimed to investigate the relationship between TSH levels and bone mineral density (BMD).

Methods

We conducted a cross-sectional study with 37,431 subjects (33,052 cases with euthyroidism and 4,379 cases with subclinical thyroid dysfunction) aged over 35 years. We performed thyroid function tests and measured BMD at the lumbar spine, femur neck, and total hip.

Results

Levels of TSH and T3 were positively correlated in women (r = 0.076, P = 0.001) and uncorrelated in men. In both men and women, TSH levels correlated positively and T3 levels correlated negatively with BMD at all skeletal sites in age and body mass index adjusted analyses. BMD increased steadily with TSH levels from the subclinical hyperthyroid to subclinical hypothyroid range in subjects with T3 levels in the highest tertile (119.5–200.0 ng/dL), but was no longer significant in subjects with lower plasma T3 levels.

Conclusions

The variations in TSH levels within the euthyroid and subclinical range were positively correlated with BMD in healthy men and women. The negative effect of T3 on BMD appears to be compensated for by increased TSH in subjects with plasma T3 levels in the upper normal range.     

Monitoring of denitrification byPseudomonas aeruginosa using on-line fluorescence technique

Summary The NAD(P)H fluorescence ofPseudomonas aeruginosa dropped sharply upon addition of nitrate to an anaerobic culture, indicating that denitrification is not limited by mass transfer of nitrate through cell membrane to reach nitrate reductase. The effect of added nitrate concentration on fluorescence drop followed a typical saturation kinetics. The maximum specific denitrification rate under the studied condition was found to be 0.26±0.05 g NO ₃ ⁻ -N/g cells-hr.