Increase in extracellular cross-linking by tissue transglutaminase and reduction in expression of MMP-9 contribute differentially to focal segmental glomerulosclerosis in rats

Tissue transglutaminase (tTG) is a Ca²⁺-dependent enzyme which stabilizes the extracellular matrix (ECM) through post-translational modification, and may play an important role in the pathogenesis of focal and segmental glomerulosclerosis (FSGS). Here, we have investigated whether tTG contributes to the glomerular ECM expansion in the puromycin aminonucleoside (PAN)-injection-induced experimental rat model of FSGS. The localization and expression of tTG, MMP-9 gelatinase, and the ECM component fibronectin (FN) in kidneys was determined by immunohistochemistry and measured by semi-quantitative analysis. Protein levels of tTG and MMP-9 were also analyzed by Western blotting.In situtransglutaminase activity was assayed by measurement of incorporated substrate and the immunofluorescence staining for the cross-linking product, ε-(γ-glutamyl) lysine. Prominent proteinuria, a typical pathological feature of FSGS, was observed in PAN injection group rats. tTG immunoreactivity was located markedly in glomeruli and the levels of this protein in whole-kidney homogenates of PAN injection group rats were significantly increased (361± 106% control, P< 0.05). Similarly, transglutaminase activity and ε-(γ-glutamyl) lysine were also predominately located within glomeruli and were much more intense in the PAN-injected group than that in control animals. MMP-9 was also located primarily within glomeruli. In PAN-injected kidneys, protein levels of active MMP-9 were significantly reduced (59± 27% control, P< 0.01), while pro-MMP-9 levels increased (148± 42% control, P< 0.05). Remarkable expression of glomerular fibronectin (FN) was found in PAN injection group rats. Semi-quantitative analysis demonstrated this increased intensity of FN staining in the PAN-injected rats was 149± 23% of the control values (P< 0.05). Enhanced cross-linking of ECM by tissue transglutaminase and decreased degradation due to reduced active MMP-9 expression may be at least partially responsible for the deposition of FN within injured glomeruli in experimental FSGS.     

黑斑蛙和中华大蟾蜍精子的超显微结构研究

过去,在精子的超显微结构方面的研究虽然已积累了很多资料,但在无尾的两栖类,蛙和蟾蜍方面的研究却不多。施履吉等（1981）结合他们的生化工作,曾用液面铺片法研究了这两种两栖类染色质在超显微结构方面的异同。发现黑斑蛙的精子染色质保留了体细胞染色质的核小体的结构,而在蟾蜍染色质中则无核小体结构,取而代之的则为由精蛋白和DNA组成的纤维状结构。然而在原位的情况下,黑斑蛙（Rana nigromacu-lata）和中华大蟾蜍（Bufo bufo asiaticus）的染色质呈何形态尚需做进一步的研究。     

云南栽培的西蒙得木种子蜡的化学成分

西蒙得木(Simmondsia chinensis)为重要油脂植物。我所引种栽培的西蒙得木种子蜡(液体蜡)经化学处理后,用GC及GC/MS分析,化学成分与原产地一致。我们采用“远端基团修饰法”确定了未见前人报道的脂肪酸的双键位置。分析结果,西蒙得木液体蜡的脂肪酸部分,其主要成分(％):十六碳烯-7-酸0.07—0.10,十八碳烯-9-酸3.73—5.92,二十碳烯-11-酸37.59—38.83,二十二碳烯-13-酸7.09—9.27,二十四碳烯-15-酸0.62—1.11。脂肪醇部分主要成分(％):十八碳烯醇0.21—0.24,二十碳烯醇16.15—22.07,二十二碳烯醇19.93—23.09,二十四碳烯醇2.96—4.96。     

绿豆VrWOX基因家族鉴定及表达分析北大核心CSCD

WOX(WUSCHEL-related homebox)基因家族是植物特有的一类转录因子,是同源盒(homeobox,HB)转录因子超家族中的重要成员。WOX基因在植物干细胞调节及生殖发育过程中具有重要作用,其功能已在多个植物物种中鉴定。然而绿豆(Vigna radiate)VrWOX基因家族信息尚不清楚。本研究通过同源比对和聚类分析,在绿豆基因组中鉴定了42个VrWOX基因。VrWOX基因在绿豆染色体中分布不均,其中7号染色体含有的VrWOX数量最多。VrWOX基因分为古老进化支(19个VrWOX)、中等进化支(12个VrWOX)和年轻进化支(WUSCHEL进化支,11个VrWOX)3个亚类。种内和种间共线性分析发现,VrWOX基因共有12个重复事件,与拟南芥(Arabidopsis thaliana)AtWOX有15个同源基因对,与菜豆(Phaseolus vulgaris)PvWOX有22个同源基因对。VrWOX基因在基因结构、保守基序等方面存在很大差异,因而可能存在功能差异。VrWOX基因启动子区域含有不同种类和不同数量的顺式作用元件,导致VrWOX基因在不同组织中表现出不同的基因表达模式。本研究对VrWOX基因家族信息和表达模式进行了分析,为绿豆VrWOX基因功能和调控网络的解析奠定了一定的理论依据。     

吉林省向日葵新引资源对黑斑病抗性鉴定

向日葵黑斑病(Alternaria helianthi(Hansford)Tubakiyet Nishihasa)在世界上分布较广,危害也较大,我国东北三省都有发生,近年在吉林省白城市向日葵主产区发生严重,因感此病而发生大范围枯死,严重影响向日葵籽实产量和质量。由于向日葵植株高大,化学防     

Plant growth depressions in arbuscular mycorrhizal symbioses: not just caused by carbon drain?

* This study investigated effects of plant density and arbuscular mycorrhizal (AM) colonization on growth and phosphorus (P) nutrition of a cultivar of wheat (Triticum aestivum) that often shows early AM-induced growth depressions. * Two experiments were conducted. Expt 1 had three plant densities and one soil P concentration. Expt 2 had two plant densities and two P concentrations. Plants were grown in calcareous P-fixing soil, inoculated with Glomus intraradices or Gigaspora margarita, or noninoculated (nonmycorrhizal (NM)). Glomus intraradices colonized well and caused a growth depression only in Expt 1. Gigaspora margarita caused large growth depressions in both experiments even though it colonized poorly. * The results showed that growth depressions were mitigated by changes in relative competition for soil P by NM and AM plants, and probably by decreasing carbon costs of the fungi. * The different effects of the two fungi appear to be attributable to differences in the balance between P uptake by the fungal pathway and direct uptake via the roots. These differences may be important in other AM symbioses that result in growth depressions. The results show that mycorrhizal growth responses of plants grown singly may not apply at the population or community level.     

Exploring the electron transfer properties of neuronal nitric-oxide synthase by reversal of the FMN redox potential

In nitric-oxide synthase (NOS) the FMN can exist as the fully oxidized (ox), the one-electron reduced semiquinone (sq), or the two-electron fully reduced hydroquinone (hq). In NOS and microsomal cytochrome P450 reductase the sq/hq redox potential is lower than that of the ox/sq couple, and hence it is the hq form of FMN that delivers electrons to the heme. Like NOS, cytochrome P450BM3 has the FAD/FMN reductase fused to the C-terminal end of the heme domain, but in P450BM3 the ox/sq and sq/hq redox couples are reversed, so it is the sq that transfers electrons to the heme. This difference is due to an extra Gly residue found in the FMN binding loop in NOS compared with P450BM3. We have deleted residue Gly-810 from the FMN binding loop in neuronal NOS (nNOS) to give Delta G810 so that the shorter binding loop mimics that in cytochrome P450BM3. As expected, the ox/sq redox potential now is lower than the sq/hq couple. Delta G810 exhibits lower NO synthase activity but normal levels of cytochrome c reductase activity. However, unlike the wild-type enzyme, the cytochrome c reductase activity of Delta G810 is insensitive to calmodulin binding. In addition, calmodulin binding to Delta G810 does not result in a large increase in FMN fluorescence as in wild-type nNOS. These results indicate that the FMN domain in Delta G810 is locked in a unique conformation that is no longer sensitive to calmodulin binding and resembles the "on" output state of the calmodulin-bound wild-type nNOS with respect to the cytochrome c reduction activity.     

A型肉毒神经毒素基因的PCR检测

目的:建立快速筛查A型肉毒毒素的PCR方法。方法:根据GenBank中报道的肉毒毒素基因序列,综合应用多种生物软件分析设计特异的检测引物,从提取的基因组DNA、热裂解产物和菌液等不同形式的模板中扩增大小为457bp的A型肉毒毒素特异基因片段,以肉毒梭菌其他血清型及破伤风梭菌为对照。结果:检测方法无交叉反应,灵敏度可达10pgDNA,3×103个菌。结论:建立的检测方法特异性强、灵敏度高,可以用于A型肉毒毒素基因的快速筛查。     

Direct and efficient cloning of full-length genes from environmental DNA by RT-qPCR and modified TAIL-PCR

Environmental DNA (eDNA) is defined as the total DNA that can be isolated from environmental samples. In total, therefore, eDNA includes a vast functional genes, and various approaches have been developed to retrieve full-length functional genes from eDNA. The efficiency of PCR amplification of eDNA is limited, however, because in truth, the net content of actual target functional genes is rather low in eDNA. To address this technical challenge, we developed a fast and effective approach to cloning full-length functional genes from eDNA. Two important modifications were made to existing PCR-based methods: first, a real-time quantitative PCR step was added to assess the difficulty of obtaining full-length genes; second, we improved the thermal asymmetric interlaced PCR program to make it more effective for cloning the flanking regions of known fragments that are present at low abundance in eDNA. Using this approach, five novel full-length functional genes with very low identity to known genes were cloned from environmental samples. This approach has great potential for allowing discovery of functional genes from environmental sources and may be broadly applicable to molecular biology research.     

植物NAC转录因子家族研究概况

植物特有的NAC家族转录因子数量众多,广泛分布于陆生植物中。NAC转录因子涉及多个生长发育和胁迫应答过程,功能多样而重要,从发现至今一直是研究的热点。ANAC019蛋白三维结构的解析和一系列NAC基因功能的揭示可以帮助我们更全面地了解NAC家族,包括它们的起源与分类、生物学功能、表达调控规律以及结构与功能的关系。该文较为详尽地阐述了NAC家族转录因子的研究现状,并展望其未来的研究方向。