Acute toxicity and adverse effects of aqueous and ethanol extracts of Parkia biglobosa pods on biochemical parameters of Clarias gariepinus

The acute toxicity of the aqueous and ethanol extracts of Parkia biglobosa pods against Clarias gariepinus was investigated under laboratory conditions. Agitated behaviours and respiratory distress were also observed during the exposure period. The adverse effects on biochemical parameters were assessed using semi-static bioassays for 28 days. The ethanol extract of P. biglobosa pods was found to be more acutely toxic with a 96 h LC₅₀ value of 13.96 mg l^?1 than the aqueous extracts, with a 96 h LC₅₀ value of 19.95 mg l^?1 against C. gariepinus. Both extracts induced agitated behaviours and respiratory distress in exposed organisms. The activities of superoxide dismutase (SOD), catalase (CAT) and the concentration of malondialdehyde (MDA) were significantly lower (p < 0.05) in groups of organisms exposed to extracts of P. biglobosa when compared with the control group after 14 days. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were also significantly (p < 0.05) lower compared with activities of the enzymes in the control group after 28 days. The current study has shown that the introduction of P. biglobosa pods into aquatic ecosystems is acutely toxic to fish and would possibly be to other non-target aquatic organisms especially invertebrates.     

阿帕替尼对人肝癌细胞增殖及凋亡的作用机制研究

目的:探讨阿帕替尼抑制肝癌细胞增殖促进凋亡的作用机制。方法:选取肝癌细胞系SNU739、HepG2,以CCK-8细胞增殖实验、平板克隆实验测定阿帕替尼对肝癌细胞增殖及克隆形成能力的影响;流式细胞术检测阿帕替尼对肝癌细胞凋亡的影响;蛋白免疫印迹法检测阿帕替尼影响肝癌细胞凋亡相关蛋白Bax、Bcl-2及Caspase3的表达情况。结果:与对照组相比,阿帕替尼可显著抑制肝癌细胞增殖(P0.05)。平板克隆实验提示与对照组相比,10μM和20μM阿帕替尼组肝癌细胞克隆数明显减少(P0.05)。流式细胞术结果提示10μM和20μM阿帕替尼处理组细胞凋亡率明显增加(P0.05)。蛋白免疫印迹法结果显示经阿帕替尼处理的肝癌细胞,促凋亡蛋白Bax及Caspase3的活性片段Cleaved-caspase3表达水平显著上调,抗凋亡蛋白Bcl-2显著下调(P0.01)。结论:阿帕替尼通过调节肝癌细胞凋亡相关蛋白从而抑制肝癌细胞增殖、促进其凋亡。     

骨髓间充质干细胞与聚3-羟基丁酸酯-co-4-羟基丁酸酯生物材料共培养细胞补片的初步研究

目的:研究聚3-羟基丁酸酯-co-4-羟基丁酸酯[P(3HB-co-4HB)]这种新型高分子材料与骨髓间充质干细胞(BMSCs)共培养,观察材料对干细胞的存活及增殖的影响,形成细胞补片的效果;从而找到一种适合BMSCs生长、增殖的高分子生物材料,作为治疗心肌梗死,软骨损伤等多种组织损伤疾病的修复方法之一。方法:取清洁级雄性健康BSL-C57小鼠作为实验对象,通过分离培养获得小鼠BMSCs,并进行流式细胞仪鉴定表面标志物。BMSCs培养至5代后,将BMSCs与P(3HB-co-4HB)制成的生物材料薄膜共培养,24h后固定进行电镜扫描,并用DAPI荧光染料染色处理,在荧光显微镜下观察并进行细胞计数,并描绘生长曲线。结果:BMSCs流式细胞术鉴定:CD34、CD45阴性,CD90弱阳性,CD73阳性。扫描电镜下,P(3HB-co-4HB)材料与BMSCs共培养形成的细胞补片,其表面细胞数量多,细胞状态正常。荧光显微镜下,对其细胞补片表面的细胞进行计数,并绘制生长曲线,显示表面细胞有逐渐增多的趋势。结论:P(3HB-co-4HB)材料与BMSCs共培养制成的细胞补片表面有细胞存活及增殖,由于P(3HB-co-4HB)材料本身具有良好的生物组织相容性及可降解等性质,所以该新型高分子材料可以作为干细胞治疗多种疾病的支架材料之一。     

昆虫杆状病毒系统表达口蹄疫病毒3ABC基因

以O型口蹄疫病毒为研究对象,经过RTPCP扩增得到非结构蛋白3ABC基因,克隆到转移载体pFastbacHT,将其转入含穿梭载体Bacmid的DH10Bac,与Bacmid发生位点特异性转座作用,得到3ABC的重组穿梭载体Bacmid3ABC,再将其转染昆虫细胞HiFive。PCR鉴定证实3ABC基因正确地插入到病毒基因组的多角体蛋白基因启动子下游,经过SDSPAGE和Westernblot检测,3ABC基因在昆虫细胞中表达了大小约为50kDa的蛋白条带,3ABC基因在BactoBac系统中的成功表达为建立以基因工程产品为抗原、鉴别诊断自然感染和免疫动物的方法提供了技术条件。     

凋亡相关基因的整合分析及基因表达芯片的制备

利用IPI和GenBank,收集了与凋亡相关的5 333条基因序列,用一定的标准,整合筛选得到1 384个凋亡相关的基因．通过亚细胞定位、组织表达差异显著性分析、自然正义/反义RNA对预测、基因簇在pathway上的定位、蛋白质/蛋白质相互作用等方面的分析发现,一些基因只在一个组织里显著差异表达,一些基因存在自然正义/反义RNA对现象,一些基因簇同时位于多条pathway等重要信息．同时,制作了一张凋亡相关基因的寡核苷酸芯片,并且对于一对NAIF1表达质粒转染前后的HeLa样品,通过该芯片的筛选,得到24个差异表达的基因．发现NAIF1过表达诱导的细胞凋亡,伴随了PAX2、PDCD8、PDCD10、DFFA、CASP7等基因表达的显著变化,同时还发现,U58668,该mRNA没有任何基因或蛋白质的注释信息,当camptothecin诱导U937细胞系凋亡时上调,在这里的NAIF1过表达诱导的HeLa细胞系中也上调(上述数据结果见http://gpcrome.cbi.pku.edu.cn:2005/chip)．     

微小RNA研究进展

MicroRNAs(miRNAs)是一类长度为21-23核苷酸(nt)、进化上比较保守的非编码蛋白质的单链小RNA分子,它们一般通过Dicer酶从具有发夹二级结构的前体RNA加工而来。在真核生物的发育、基因表达等一系列过程中发挥了重要作用。     

常温和低温下保存小新月菱形藻的包埋-脱水法

用包埋.脱水法在常温和低温下保存小新月菱形藻(Nitzschla closterium f.minutissima),探讨了温度、光(暗)、含水量,密封袋内空间体积和密封袋外膜材质等因素对保存效果的影响.结果表明,小新月菱形藻在4℃下暗保存6个月后的最高存活率达到80.4%.而且,保存后的藻细胞经过恢复培养后,其生长力可达到保存前的水平.包埋.脱水法操作简单.无需复杂设备,在藻类种质保存中有广阔的应用前景.     

氯喹与氟康唑联合对新生隐球菌的体外药敏实验

目的研究氯喹与氟康唑体外联合应用对隐球菌生长作用的影响。方法参考M27-A方案,检测10μmol/L,100μmol/L与1 000μmol/L 3种浓度氯喹与氟康唑联合后对20株菌株的氟康唑对隐球菌最小抑菌浓度与最小杀菌浓度的变化。结果与10μmol/L氯喹组相比,100μmol/L以上浓度的氯喹组可以显著降低氟康唑对隐球菌的M IC与MFC。结论氯喹在体外可以提高氟康唑抗隐球菌的作用,与氟康唑具有协同抗隐球菌的作用。     

The role of PilZ domain proteins in the virulence of Xanthomonas campestris pv. campestris

Cyclic di‐GMP [(bis‐(3′–5′)‐cyclic di‐guanosine monophosphate)] is an almost ubiquitous second messenger in bacteria that is implicated in the regulation of a range of functions that include developmental transitions, aggregative behaviour, adhesion, biofilm formation and virulence. Comparatively little is known about the mechanism(s) by which cyclic di‐GMP exerts these various regulatory effects. PilZ has been identified as a cyclic di‐GMP binding protein domain; proteins with this domain are involved in regulation of specific cellular processes, including the virulence of animal pathogens. Here we have examined the role of PilZ domain proteins in virulence and the regulation of virulence factor synthesis in Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot of crucifers. The Xcc genome encodes four proteins (XC0965, XC2249, XC2317 and XC3221) that have a PilZ domain. Mutation of XC0965, XC2249 and XC3221 led to a significant reduction of virulence in Chinese radish. Mutation of XC2249 and XC3221 led to a reduction in motility whereas mutation of XC2249 and XC0965 affected extracellular enzyme production. All mutant strains were unaffected in biofilm formation in vitro. The reduction of virulence following mutation of XC3221 could not be wholly attributed to an effect on motility as mutation of pilA, which abolishes motility, has a lesser effect on virulence.