不同生境濒危植物龙棕种群结构及其动态特征

【目的】分析不同生境下龙棕种群结构及动态特征,探究其主要影响因素,为该区龙棕种群的保护、恢复和更新提供基础的理论依据。【方法】通过对楚雄州大尖山自然保护区内3种不同生境(阔叶林、针阔混交林、灌丛)龙棕种群调查,编制龙棕种群的静态生命表和绘制其存活曲线和生存分析函数曲线,并利用时间序列模型对种群的数量动态做出相应的预测,以深入了解不同生境下龙棕种群结构及动态特征。【结果】(1)在3种生境中龙棕种群均处于衰退状态,对外界干扰较为灵敏,存活曲线呈现Deevey-Ⅲ型,龙棕个体在幼苗阶段出现大量死亡。(2)3种不同生境下龙棕种群都分布不均,呈聚集分布,说明龙棕种子传播以母株为中心扩散。【结论】从种群密度大小上来看,阔叶林中的龙棕种群密度最大,其次是针阔混交林,最小的是灌丛。结合对种群年龄结构的研究,进一步证明水分条件较好的阔叶林和针阔混交林更有利于龙棕种群的生存。     

GDC-0152-induced autophagy promotes apoptosis in HL-60 cells

Cardiac hormones, atrial and brain natriuretic peptides (ANP and BNP), have pivotal roles in renal hemodynamics, neuroendocrine signaling, blood pressure regulation, and cardiovascular homeostasis. Binding of ANP and BNP to the guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) induces rapid internalization and trafficking of the receptor via endolysosomal compartments, with concurrent generation of cGMP. However, the mechanisms of the endocytotic processes of NPRA are not well understood. The present study, using ¹²⁵I-ANP binding assay and confocal microscopy, examined the function of dynamin in the internalization of NPRA in stably transfected human embryonic kidney-293 (HEK-293) cells. Treatment of recombinant HEK-293 cells with ANP time-dependently accelerated the internalization of receptor from the cell surface to the cell interior. However, the internalization of ligand–receptor complexes of NPRA was drastically decreased by the specific inhibitors of clathrin- and dynamin-dependent receptor internalization, almost 85% by monodansylcadaverine, 80% by chlorpromazine, and 90% by mutant dynamin, which are specific blockers of endocytic vesicle formation. Visualizing the internalization of NPRA and enhanced GFP-tagged NPRA in HEK-293 cells by confocal microscopy demonstrated the formation of endocytic vesicles after 5 min of ANP treatment; this effect was blocked by the inhibitors of clathrin and by mutant dynamin construct. Our results suggest that NPRA undergoes internalization via clathrin-mediated endocytosis as part of its normal itinerary, including trafficking, signaling, and metabolic degradation.     

Novel inhibitors of As(III) S-adenosylmethionine methyltransferase (AS3MT) identified by virtual screening

Due to increased interest in As(III) S-adenosylmethionine methyltransferase (AS3MT), a search for chemical probes that can help elucidate function was initiated. A homology model was built based on related enzymes, and virtual screening produced 426 potential hits. Evaluation of these compounds in a functional enzymatic assay revealed several modest inhibitors including an O-substituted 2-amino-3-cyano indole scaffold. Two iterations of near neighbor searches revealed compound 5 as a potent inhibitor of AS3MT with good selectivity over representative methyltransferases DOT1L and NSD2 as well as a representative set of diverse receptors. Compound 5 should prove to be a useful tool to investigate the role of AS3MT and a potential starting point for further optimization.     

Increased AURKA promotes cell proliferation and predicts poor prognosis in bladder cancer

Background

Bladder cancer (BC) is the most common cancer of the urinary bladder and upper tract, in which the clinical management is limited. AURKA (aurora kinase A) has been identified as an oncogene in cancer development; however, its potential role and underlying mechanisms in the progression of BC remain unknown.

Results

In this study, we evaluated Aurora kinase A (AURKA) expression in patient samples by performing gene expression profiling, and found that AURKA expression levels were significantly higher in BC tissues than in normal tissues. Increased AURKA in BC was strongly associated with stage and grade. Moreover, BC patients with elevated AURKA achieved poor overall survival rates. The experiments in vitro comprehensively validated the critical role of AURKA in promoting BC cell proliferation using the methods of gene overexpression and gene silencing. Furthermore, we proved that AURKA inhibitor MLN8237 arrested BC cell growth and induced apoptosis.

Conclusions

These findings implicate AURKA acting as an effective biomarker for BC detection and prognosis, as well as therapeutic target.

     

Secretory expression of α single-chain insulin precursor in yeast and its conversion into human insulin

A synthetic single-chain porcine insulin precursor (PIP) gene and an α-mating factor leader sequence (αMFL) gene obtained by the PCR method are inserted between the promoter and 3'-terminating sequence of the alcohol dehydrogenase gene ADH1 in plasmid pVT102-U to form plasmid pVT102-U/α MFL-PIP. The single-chain insulin precursor is expressed and secreted to the culture medium by Saccharomyces cererisiae transformed by pVT102-U/αMFL-PIP. The precursor is purified and converted into human insulin by tryptic transpeptidation. The purified human insulin is fully active and can be crystallized. The overall yield of human insulin is 25 mg per liter of culture medium.     

Genetic predisposition of six well‐defined polymorphisms in HMGB1/RAGE pathway to breast cancer in a large Han Chinese population

Breast cancer constitutes an enormous burden in China. A strong familial clustering of breast cancer suggests a genetic component in its carcinogenesis. To examine the genetic predisposition of high mobility group box‐1/receptor for advanced glycation end products (HMGB1/RAGE) pathway to breast cancer, we genotyped six well‐defined polymorphisms in this pathway among 524 breast cancer patients and 518 cancer‐free controls from Heilongjiang province, China. There were no deviations from Hardy–Weinberg equilibrium for all polymorphisms. In single‐locus analysis, the frequency of rs1800624 polymorphism mutant A allele in RAGE gene was significantly higher in patients than in controls (24.52% versus 19.50%, P = 0.006), with the carriers of rs1800624‐A allele being 1.51 times more likely to develop breast cancer relative to those with rs1800624‐GG genotype after adjustment (95% confidence interval or CI: 1.17–1.94, P = 0.001). In HMGB1 gene, haplotype analysis did not reveal any significance, while in RAGE gene, haplotypes C‐T‐A and C‐A‐G (alleles in order of rs1800625, rs18006024, rs2070600) were significantly associated with an increased risk of breast cancer (adjusted OR = 2.72 and 10.35; 95% CI: 1.20–6.18 and 1.58–67.80; P = 0.017 and 0.015 respectively). In further genetic score analysis, per unit and quartile increments of unfavourable alleles were significantly associated with an increased risk of breast cancer after adjustment (odds ratio or OR = 1.20 and 1.26; 95% CI: 1.09–1.32 and 1.12–1.42; P < 0.001 and <0.001 respectively). Our findings altogether demonstrate a significant association between RAGE gene rs1800624 polymorphism and breast cancer risk, and more importantly a cumulative impact of multiple risk associated polymorphisms in HMGB1/RAGE pathway on breast carcinogenesis.     

HLA-DR和DQ cDNA亚探针减少由限制片段长度多态性作DR分型的复杂性

在DNA水平上鉴定HLA-DR等位基因是一种适用于任何有核细胞的分型技术。DNA分型的主要问题是解释Southern印迹分析中杂交片段的复杂格局,这在杂合个体尤为困难。为此,我们从DRβ、DQβ和DQα全长cDNA探针建立了亚探针,以便减少杂交片段的数目,从而降低限制片段长度多态性(RFLP)的复杂性。我们发现内切酶PvuⅡ和DRβ3'端不翻译区亚探针,而对一些DR等位基因作出鉴定。这些简化了的杂交片段格局有利于对一些杂合个体作DNA分型。     

羧甲基茯苓聚糖的制备及性质研究

作者采用水媒法和溶媒法,分别将茯苓聚糖直接羧甲基化,得到了具有抗肿瘤活性的羧甲基茯苓聚糖,并对产物进行了IR、~(13)CNMR分析。     

Catalytic properties of a mutant beta-galactosidase from Xanthomonas manihotis engineered to synthesize galactosyl-thio-beta-1,3 and -beta-1,4-glycosides

The identity of the acid/base catalyst of the Family 35 beta-galactosidases from Xanthomonas manihotis (BgaX) has been confirmed as Glu184 by kinetic analysis of mutants modified at that position. The Glu184Ala mutant of BgaX is shown to function as an efficient thioglycoligase, which synthesises thiogalactosides with linkages to the 3 and 4 positions of glucosides and galactosides in high (>80%) yields. Kinetic analysis of the thioglycoligase reveals glycosyl donor K(m) values of 1.5-21 microM and glycosyl acceptor K(m) values from 180 to 500 microM. This mutant should be a valuable catalyst for the synthesis of metabolically stable analogues of this important glycosidic linkage.