Red/ET同源重组技术及其在微生物基因组挖掘中的应用进展

Red/ET同源重组技术(Red/ET recombineering)是由来源于大肠杆菌λ噬菌体的蛋白对Redα/Redβ或来源于Rac原噬菌体的蛋白对Rec E/Rec T所介导的基于短同源臂(40–50 bp)的同源重组技术,能对宿主DNA序列进行快速、高效、精确的修饰和操作。本文主要综述了2010年以来Red/ET同源重组技术在大肠杆菌及其他细菌中的研究进展,同时简要介绍了该技术在微生物基因组挖掘,尤其是在微生物基因簇的异源表达领域的应用进展。     

Downregulated E-Cadherin Expression Indicates Worse Prognosis in Asian Patients with Colorectal Cancer: Evidence from Meta-Analysis

Background

Epithelial-mesenchymal transition (EMT) plays a crucial role in the progression and aggressiveness of colorectal carcinoma. E-cadherin is the best-characterized molecular marker of EMT, but its prognostic significance for patients with CRC remains inconclusive.

Methodology

Eligible studies were searched from the PubMed, Embase and Web of Science databases. Correlation between E-cadherin expression and clinicopathological features and prognosis was analyzed. Subgroup analysis was also performed according to study location, number of patients, quality score of studies and cut-off value.

Principal Findings

A total of 27 studies comprising 4244 cases met the inclusion criteria. Meta-analysis suggested that downregulated E-cadherin expression had an unfavorable impact on overall survival (OS) of CRC (n = 2730 in 14 studies; HR = 2.27, 95%CI: 1.63–3.17; Z = 4.83; P = 0.000). Subgroup analysis indicated that low E-cadherin expression was significantly associated with worse OS in Asian patients (n = 1054 in 9 studies; HR = 2.86, 95%CI: 2.13–3.7, Z = 7.11; P = 0.000) but not in European patients (n = 1552 in 4 studies; HR = 1.14, 95%CI: 0.95–1.35, Z = 1.39; P = 0.165). In addition, reduced E-cadherin expression indicated an unfavorable OS only when the cut off value of low E-cadherin expression was >50% (n = 512 in 4 studies; HR = 2.08, 95%CI 1.45–2.94, Z = 4.05; P = 0.000). Downregulated E-cadherin expression was greatly related with differentiation grade, Dukes'' stages, lymphnode status and metastasis. The pooled OR was 0.36(95%CI: 0.19–0.7, Z = 3.03, P = 0.002), 0.34(95%CI: 0.21–0.55, Z = 6.61, P = 0.000), 0.49(95%CI: 0.32–0.74, Z = 3.02, P = 0.002) and 0.45(95%CI: 0.22–0.91, Z = 3.43, P = 0.001), respectively.

Conclusions

This study showed that low or absent E-cadherin expression detected by immunohistochemistry served as a valuable prognostic factor of CRC. However, downregulated E-cadherin expression seemed to be associated with worse prognosis in Asian CRC patients but not in European CRC patients. Additionally, this meta-analysis suggested that the negative threshold of E-cadherin should be >50% when we detected its expression in the immunohistochemistry stain.     

Molecular Subtypes in Head and Neck Cancer Exhibit Distinct Patterns of Chromosomal Gain and Loss of Canonical Cancer Genes

Head and neck squamous cell carcinoma (HNSCC) is a frequently fatal heterogeneous disease. Beyond the role of human papilloma virus (HPV), no validated molecular characterization of the disease has been established. Using an integrated genomic analysis and validation methodology we confirm four molecular classes of HNSCC (basal, mesenchymal, atypical, and classical) consistent with signatures established for squamous carcinoma of the lung, including deregulation of the KEAP1/NFE2L2 oxidative stress pathway, differential utilization of the lineage markers SOX2 and TP63, and preference for the oncogenes PIK3CA and EGFR. For potential clinical use the signatures are complimentary to classification by HPV infection status as well as the putative high risk marker CCND1 copy number gain. A molecular etiology for the subtypes is suggested by statistically significant chromosomal gains and losses and differential cell of origin expression patterns. Model systems representative of each of the four subtypes are also presented.     

A photo‐responsive F‐box protein FOF2 regulates floral initiation by promoting FLC expression in Arabidopsis

Floral initiation is regulated by various genetic pathways in response to light, temperature, hormones and developmental status; however, the molecular mechanisms underlying the interactions between different genetic pathways are not fully understood. Here, we show that the photoresponsive gene FOF2 (F‐box of flowering 2) negatively regulates flowering. FOF2 encodes a putative F‐box protein that interacts specifically with ASK14, and its overexpression results in later flowering under both long‐day and short‐day photoperiods. Conversely, transgenic plants expressing the F‐box domain deletion mutant of FOF2 (FOF2ΔF), or double loss of function mutant of FOF2 and FOL1 (FOF2‐LIKE 1) present early flowering phenotypes. The late flowering phenotype of the FOF2 overexpression lines is suppressed by the flc‐3 loss‐of‐function mutation. Furthermore, FOF2 mRNA expression is regulated by autonomous pathway gene FCA, and the repressive effect of FOF2 in flowering can be overcome by vernalization. Interestingly, FOF2 expression is regulated by light. The protein level of FOF2 accumulates in response to light, whereas it is degraded under dark conditions via the 26S proteasome pathway. Our findings suggest a possible mechanistic link between light conditions and the autonomous floral promotion pathway in Arabidopsis.     

龙须藤叶粗提物的分离纯化及生物活性初探

为进一步研究和开发新植物源农药,拓宽龙须藤(Bauhinia championii)的生物活性研究,探索其不同组分潜在的杀菌和除草活性,该研究通过常温冷浸提取法提取、真空浓缩得到甲醇提取物。结果表明:用硅胶柱层析分离纯化,经TLC检识和碘缸显色后整合得到9个组分。反复重结晶7号和8号组分中析出的物质,经TLC检识和测熔点,得到1个纯化合物,编为33号,经波谱数据分析与molbase库对照,鉴定该化合物为(1R,2S,3S,4S,5S,6S)-6-甲氧基-1,2,3,4,5-环己烷五醇,是一种重要的工业原料。杀菌和除草活性试验结果显示,粗提物在1 000μg·m L~(-1)时对水稻稻瘟病菌的抑制率为(40.84±1.00)%,对稗草根的抑制率为(49.18±2.33)%;各组分在500μg·m L~(-1)时,4号组分对水稻稻瘟病菌的抑制率达到(44.19±0.76)%,2号和3号组分对稗草根的抑制率分别为(88.92±1.31)%和(90.99±1.45)%,3号和6号组分对马齿苋根的抑制率分别为(72.06±1.31)%和(89.92±1.73)%。这表明龙须藤叶提取物对水稻稻瘟病菌、稗草根和马齿苋根有良好的抑制效果,可进一步分离2号、3号、4号、6号组分,以获得高活性的单体化合物。     

miR-1260b promotes cell migration and invasion of hepatocellular carcinoma by targeting the regulator of G-protein signaling 22

Objectives

To investigate whether miR-1260b can regulate migration and invasion of hepatocellular carcinoma (HCC) by targeting RGS22.

Results

miR-1260b was up-regulated in HCC tissues compared with their corresponding non-cancerous tissues. Over-expression of miR-1260b increased migration and invasion of HepG2 and SMMC-7721 cells associated with HCC. Regulator of G-protein signaling 22 (RGS22) was identified as a directly target of miR-1260b and was inhibited by miR-1260b. Knockdown of RGS22 increased proliferation of HCC cells.

Conclusions

The new identified miR-1260b/RGS22 axis provides useful therapeutic methods for treatment of HCC deepening on our understanding of underlying mechanisms of HCC tumorigenesis.

     

广西百色盆地高岭坡遗址的地层及年代

广西百色盆地旧石器工业因含有众多的手斧且年代早到803 kaBP而闻名于世。盆地内发育有7级河流阶地,其中第IV级阶地发现有手斧和玻璃陨石。自从1973年第一个石器地点被发现,越来越多的遗址或地点被调查发现和发掘。以前研究认为,百色盆地旧石器只出自网纹红土层,年代均为803 kaBP。2013年以前,通常只在土状堆积的上部发掘,从来没有人对第IV级阶地的沉积物从地表到底部砾石层进行系统发掘,因此关于第IV级阶地的整体地层堆积情况及含石器层位很模糊。2013-2014年,广西文物保护与考古研究所会同田东县博物馆对百色盆地最重要的旧石器遗址之一——田东高岭坡遗址进行了系统的考古发掘。此次发掘从遗址的地表往下一直发掘到砾石层,揭露出厚度超过7m的完整地层序列,发现1处小型石器制造场和1处用火遗迹。在不同地层中发现石制品800多件,包括砍砸器、手镐、刮削器等。涵盖旧石器和新石器两个时代。根据地层对比和石制品的特征及测年结果,我们把旧石器时代文化遗存可分为3期:第一期的年代早于或等于803 kaBP,第二期为15 kaBP,第三期约为10 kaBP。