谷氨酰胺高产菌株在不同NH4+浓度下的基因差异表达

GH15菌株在高NH₄⁺浓度下能够积累过量的谷氨酰胺,并且随着NH₄⁺浓度的增加,谷氨酰胺的产量逐渐增加,但谷氨酸的产量却逐渐降低,这表明该菌株在不同NH₄⁺浓度下其高胞内的氮代谢及调控行为有很大的改变。利用抑制消减杂交技术分别构建了NH₄⁺菌株在高NH₄⁺浓度下和低NH₄⁺浓度下的基因表达抑制消减文库。通过对文库的测序得到了35个差异表达的基因。这些差异基因主要是细胞生长相关基因、能量代谢基因以及氨基酸合成代谢相关的基因,我们认为正是这些基因差异导致该菌株在高NH₄⁺下高产谷氨酰胺。     

Source apportionment and health risk assessment of heavy metals in agricultural soils in Xinglonggang,Northeastern China

Heavy metals in soil can affect human health through the exposure pathways of oral ingestion, dermal contact, and inhalation. In this study, to assess the health risk of heavy metals in the agricultural area of Xinglonggang, 52 soil samples were collected and tested to obtain the concentrations of As, Cd, Cr, Cu, Ni, Pb, V, and Zn in the soil. The enrichment factor indicated that the heavy metals of the agricultural soils were enriched, but the degree of enrichment was mild for all of the heavy metals. Coefficient analysis and principal component analysis indicated that V, Cr, Ni, and Pb were mainly from natural sources, As was from irrigation, Cu and Cd tended to be from chemical fertilizers and pesticides, and Zn was from mixed sources including irrigation, chemical fertilizers, and pesticides. A human-health risk assessment indicated that the residents in the study area face high risk from carcinogens and low risk from noncarcinogens; As and Cr are the major heavy metals affecting human health. This study provides a reference and a basis for formulating effective measures to prevent and control heavy metal enrichment in agricultural soils.     

ERp29 affects the migratory and invasive ability of human extravillous trophoblast HTR‐8/SVneo cells via modulating the epithelial‐mesenchymal transition

Dysfunction of trophoblast metastasis into the endometrium is the main cause of pre‐eclampsia (PE); however, the factors affecting this process are still unclear. In this study, we found that endoplasmic reticulum protein 29 (ERp29), one molecular chaperone of the endoplasmic reticulum, was aberrantly upregulated in the placenta of pre‐eclamptic patients compared with healthy controls. Then, an in vitro study using human extravillous trophoblast HTR‐8/SVneo cells showed that ERp29 upregulation could inhibit the migratory and invasive ability of HTR‐8/SVneo cells, while ERp29 downregulation had the opposite effect. Mechanical experiments confirmed that ERp29 blocked trophoblast metastasis via inhibiting the process of epithelial‐mesenchymal transition and affecting the Wnt/β‐catenin signaling pathway. In conclusion, this study revealed the important role of ERp29 in trophoblast metastasis and improved the mechanical understanding of PE occurrence.     

抗速灭威单链抗体基因在巴斯德毕赤酵母中的表达及性质研究

选用巴斯德毕赤酵母(Pichia pastoris)系统表达特异性抗速灭威单链抗体(scFv)基因,以为速灭威特异性抗体的大量制备奠定基础。设计引物扩增阳性克隆scFv基因,亚克隆至表达载体pPICZαC,获得重组酵母表达质粒pPICZαC-scFv,线性化pPICZαC-scFv并高效电转P.pastoris(X-33),对转化子进行抗性梯度筛选得到一株高效表达的X-33-Pp-SMW-12-6菌株。对获得的菌株先后进行表达条件的优化、优化条件下的诱导表达及单链抗体性质研究。结果表明:P.pastoris-scFv的质量接近其亲本E.coli-scFv的质量,X-33-Pp-SMW12-6在优化条件下的表达产量达28mg/L,比未优化前的产量提高了约8mg/L,经纯化后抗体纯度可达85%以上。因此,利用P.pastoris表达系统制备抗速灭威单链抗体比细菌表达系统更有效、更经济。     

Correlation between Ureaplasma Subgroup 2 and Genitourinary Tract Disease Outcomes Revealed by an Expanded Multilocus Sequence Typing (eMLST) Scheme

The multilocus sequence typing (MLST) scheme of Ureaplasma based on four housekeeping genes (ftsH, rpL22, valS, and thrS) was described in our previous study; here we introduced an expanded MLST (eMLST) scheme with improved discriminatory power, which was developed by adding two putative virulence genes (ureG and mba-np1) to the original MLST scheme. To evaluate the discriminatory power of eMLST, a total of 14 reference strains of Ureaplasma serovars and 269 clinical strains (134 isolated from symptomatic patients and 135 obtained from asymptomatic persons) were investigated. Our study confirmed that all 14 serotype strains could successfully be differentiated into 14 eMLST STs (eSTs), while some of them could not even be differentiated by the MLST, and a total of 136 eSTs were identified among the clinical isolates we investigated. In addition, phylogenetic analysis indicated that two genetically significantly distant clusters (cluster I and II) were revealed and most clinical isolates were located in cluster I. These findings were in accordance with and further support for the concept of two well-known genetic lineages (Ureaplasma parvum and Ureaplasma urealyticum) in our previous study. Interestingly, although both clusters were associated with clinical manifestation, the sub-group 2 of cluster II had pronounced and adverse effect on patients and might be a potential risk factor for clinical outcomes. In conclusion, the eMLST scheme offers investigators a highly discriminative typing tool that is capable for precise epidemiological investigations and clinical relevance of Ureaplasma.     

Joint Effects of Habitat Heterogeneity and Species’ Life-History Traits on Population Dynamics in Spatially Structured Landscapes

Both habitat heterogeneity and species’ life-history traits play important roles in driving population dynamics, yet there is little scientific consensus around the combined effect of these two factors on populations in complex landscapes. Using a spatially explicit agent-based model, we explored how interactions between habitat spatial structure (defined here as the scale of spatial autocorrelation in habitat quality) and species life-history strategies (defined here by species environmental tolerance and movement capacity) affect population dynamics in spatially heterogeneous landscapes. We compared the responses of four hypothetical species with different life-history traits to four landscape scenarios differing in the scale of spatial autocorrelation in habitat quality. The results showed that the population size of all hypothetical species exhibited a substantial increase as the scale of spatial autocorrelation in habitat quality increased, yet the pattern of population increase was shaped by species’ movement capacity. The increasing scale of spatial autocorrelation in habitat quality promoted the resource share of individuals, but had little effect on the mean mortality rate of individuals. Species’ movement capacity also determined the proportion of individuals in high-quality cells as well as the proportion of individuals experiencing competition in response to increased spatial autocorrelation in habitat quality. Positive correlations between the resource share of individuals and the proportion of individuals experiencing competition indicate that large-scale spatial autocorrelation in habitat quality may mask the density-dependent effect on populations through increasing the resource share of individuals, especially for species with low mobility. These findings suggest that low-mobility species may be more sensitive to habitat spatial heterogeneity in spatially structured landscapes. In addition, localized movement in combination with spatial autocorrelation may increase the population size, despite increased density effects.     

内蒙古黄土丘陵沟壑区生态系统健康评价

采用指标体系评价法,按自然指标体系,从生态系统活力、组织结构、系统服务功能和土壤健康等方面,以内蒙古黄土丘陵沟壑区为研究对象,分别选择原生植被区、人工恢复治理区、退化未治理区等3个样区,对其生态系统健康状况进行分析和评价,提出了适合于该区域的生态系统健康评价指标体系和权重体系,建立了适合于该区域的生态系统健康评价指数、评价模型和指标分级标准。最后,从自然生态学角度,结合研究区的实际情况,对该区域的生态系统健康恢复途径、生态系统管理和可持续发展策略提出了一些具有针对性的建议和措施,并对生态系统健康评价的进一步研究进行了展望。