嗜酸氧化亚铁硫杆菌基因组分泌蛋白的初步分析

利用信号肽预测软件SignalP v3.0、跨膜螺旋结构预测软件TMHMM v2.0和非经典分泌蛋白预测软件SecretomeP对嗜酸氧化亚铁硫杆菌全基因组的3 218个氨基酸序列进行预测分析.结果表明在嗜酸氧化亚铁硫杆菌中有507个蛋白为分泌蛋白,其中分泌型信号肽120个(其中有9个为RR-motif亚组型信号肽),脂蛋白信号肽3个,Prepilin-like信号肽4个,非经典分泌蛋白380个.并对分泌型信号肽的长度分布、氨基酸使用频率和酶切位点的氨基酸使用频率作了统计.得分最高的100个非经典分泌蛋白中,有36个具有功能分类,主要是参与细胞壁、能量代谢及转运和结合的蛋白质.嗜酸氧化亚铁硫杆菌的这507个分泌蛋白所参与的生化过程可能发生在膜外的周质空间或是菌体外的场所,为该物种与矿物相互作用,以及对环境做出响应服务.     

Three-dimensional in vitro tumor models for cancer research and drug evaluation

Cancer occurs when cells acquire genomic instability and inflammation, produce abnormal levels of epigenetic factors/proteins and tumor suppressors, reprogram the energy metabolism and evade immune destruction, leading to the disruption of cell cycle/normal growth. An early event in carcinogenesis is loss of polarity and detachment from the natural basement membrane, allowing cells to form distinct three-dimensional (3D) structures that interact with each other and with the surrounding microenvironment. Although valuable information has been accumulated from traditional in vitro studies in which cells are grown on flat and hard plastic surfaces (2D culture), this culture condition does not reflect the essential features of tumor tissues. Further, fundamental understanding of cancer metastasis cannot be obtained readily from 2D studies because they lack the complex and dynamic cell–cell communications and cell–matrix interactions that occur during cancer metastasis. These shortcomings, along with lack of spatial depth and cell connectivity, limit the applicability of 2D cultures to accurate testing of pharmacologically active compounds, free or sequestered in nanoparticles. To recapitulate features of native tumor microenvironments, various biomimetic 3D tumor models have been developed to incorporate cancer and stromal cells, relevant matrix components, and biochemical and biophysical cues, into one spatially and temporally integrated system. In this article, we review recent advances in creating 3D tumor models employing tissue engineering principles. We then evaluate the utilities of these novel models for the testing of anticancer drugs and their delivery systems. We highlight the profound differences in responses from 3D in vitro tumors and conventional monolayer cultures. Overall, strategic integration of biological principles and engineering approaches will both improve understanding of tumor progression and invasion and support discovery of more personalized first line treatments for cancer patients.     

Allele-specific targeting of hsa-miR-657 to human IGF2R creates a potential mechanism underlying the association of ACAA-insertion/deletion polymorphism with type 2 diabetes

The biological mechanism of a recent discovered association of type 2 diabetes with the ACAA-insertion/deletion polymorphism at the 3′UTR of the IGF2R gene has remained unclear. A very recently emerging novel polymorphic control layer by microRNAs (miRNAs) makes it possible to elucidate this issue. In this study, a prediction by web tools MicroInspector and miRanda demonstrated that DNA sequence polymorphism (DSPs) ACAA-insertion/deletion in IGF2R 3′UTR is located within the hsa-miR-657 and hsa-miR-453 binding sites. And luciferase reporter assay revealed that hsa-miR-657 acts directly at the 3′UTR of the IGF2R. Furthermore, ACAA-deletion exerted a further repression compared with ACAA-insertion, indicating that hsa-miR-657 regulates IGF2R gene expression in a polymorphic control manner. Importantly, we also demonstrated that hsa-miR-657 can translationally regulate the IGF2R expression levels in Hep G2 cells. Thus, our findings testify the possibility that the ACAA-insertion/deletion polymorphism may result in the change of IGF2R expression levels at least in part by hsa-miR-657-mediated regulation, contributing to the elucidation for the pathogenesis of type 2 diabetes and raise the possibility that miRNAs or in combination with functional DNA sequence polymorphism may be valuable in the treatment of human type 2 diabetes.     

杨树刺槐混交林及纯林枯落叶分解

研究了杨树（Ｐｏｐｕｌｕｓｓｐｐ．）、刺槐（Ｒｏｂｉｎｉａｐｓｅｕｄｏａｃａｃｉａ）纯林及混交林枯落叶一年中的分解及养分动态变化规律．结果表明,杨树枯落叶分解速度较慢,刺槐较快,而混交林则较杨树有较大提高．在分解过程中,杨树枯落叶Ｎ、Ｐ释放困难,需经过长达１０个月的养分富积过程;刺槐枯落叶Ｎ、Ｐ元素释放较为容易;混交林枯落叶养分富积时间缩短、幅度下降,分解速度加快,说明杨树和刺槐混交有利于枯落叶分解和Ｎ、Ｐ循环．     

含铬重组液激活部分缺失金属原子簇的钼铁蛋白的研究

棕色固氮菌（Ａｚｏｔｏｂａｃｔｅｒ ｖｉｎｅｌａｎｄｉｉ）固氮酶钼铁蛋白经邻菲口罗啉和Ｏ２ 处理后,变为部分缺失ＦｅＭｏｃｏ 和Ｐ－ｃｌｕｓｔｅｒ的失活蛋白。与由Ｋ２ＣｒＯ４、高柠檬酸铁、Ｎａ２Ｓ和二硫苏糖醇组成的重组液保温后,处理蛋白对乙炔和质子还原的活性都得以显著恢复;然而,它的吸收光谱和圆二色谱虽有明显恢复,但仍与还原钼铁蛋白有所不同。这表明,激活蛋白中也许存在功能与钼铁蛋白相似,而结构则有所差异的含铬（ＣｒＦｅ）蛋白     

我国桔梗上一种新病害匍柄霉叶斑病的病原

2013年在内蒙古赤峰市喀喇沁旗发现桔梗匍柄霉叶斑病,该病害在2014-2017年均再次发生。采用单孢分离法在病叶上得到病原菌,于PCA培养基上培养后,在光学显微镜下观察记录病原菌形态学特征。同时将病原菌的rDNA ITS、gpd和EF-1α的PCR产物测序后做BLAST分析。结果表明该菌与桔梗匍柄霉Stemphylium platycodontis基本一致。这是国内桔梗匍柄霉叶斑病的首次详细报道。     

一株产纤维素酶细菌的分离鉴定及酶学特性研究

从采集的含腐烂树叶的土壤中,筛选到1株产纤维素酶能力较高的菌株JJ-3,经16S r RNA基因序列分析,鉴定该菌株为产酸克雷伯氏杆菌(Klebsiella oxytoca)。产酶条件及酶学特性研究表明:以滤纸为碳源、蛋白胨为氮源、初始p H为8.0的培养基中发酵3 d更利于纤维素酶的合成;菌株发酵液在中性和碱性条件下均有较高的滤纸酶活力,分别可达118.7 U/m L(p H7.0),167.8 U/m L(p H8.0)和120 U/m L(p H9.0);所产纤维素酶的最适酶反应p H为7.0,最适酶反应温度为40℃,对温度比较敏感,在p H7.0-8.0的范围内具有较好的稳定性,能满足中性和碱性纤维素酶的要求。