Insight into the interaction of antitubercular and anticancer compound clofazimine with human serum albumin: spectroscopy and molecular modelling

The binding of clofazimine to human serum albumin (HSA) was investigated by applying optical spectroscopy and molecular docking methods. Fluorescence quenching data revealed that clofazimine binds to protein with binding constant in the order of 10⁴ M^?1, and with the increase in temperature, Stern–Volmer quenching constants gradually decreased indicating quenching mode to be static. The UV–visible spectra showed increase in absorbance upon interaction of HSA with clofazimine which further reveals formation of the drug–albumin complex. Thermodynamic parameters obtained from fluorescence data indicate that the process is exothermic and spontaneous. Forster distance (R_o) obtained from fluorescence resonance energy transfer is found to be 2.05 nm. Clofazimine impelled rise in α-helical structure in HSA as observed from far-UV CD spectra while there are minor alterations in tertiary structure of the protein. Clofazimine interacts strongly with HSA inducing secondary structure in the protein and slight alterations in protein topology as suggested by dynamic light scattering results. Moreover, docking results indicate that clofazimine binds to hydrophobic pocket near to the drug site II in HSA.     

鸭疫里默氏杆菌Mtan对底物SAH的催化活性

【目的】分析鸭疫里默氏杆菌(Riemerella anatipestifer,RA)不同血清型pfs基因的序列差异,并开展其编码蛋白S-腺苷高半胱氨酸核苷酶(Mtan,又称Pfs)的催化活性研究。【方法】PCR扩增9株不同血清型RA的pfs基因,分析其核苷酸序列的同源性;构建该基因的重组表达载体p Cold-RA-pfs,表达、纯化RA的重组蛋白Mtan(RA-Mtan);测定RA-Mtan对底物S-腺苷同型半胱氨酸(S-adenosylhomocysteine,SAH)的催化活性,运用哈维弧菌报告菌株BB170检测催化底物的自诱导物2(Autoinducer-2,AI-2)活性。【结果】对RA的pfs序列分析结果表明,不同血清型RA的核苷酸一致性在93.9%-100%之间;SDS-PAGE检测结果表明,RA-Mtan呈可溶性表达;酶活测定表明RA-Mtan和禽致病性大肠杆菌(Avain pathogenic Escherichia coli,APEC)的Lux S蛋白共同作用于底物时,可产生浓度为176.7μmol/L的同型半胱氨酸(Homocysteine,HCY);AI-2活性检测结果表明,产生的AI-2具有生物学活性。【结论】RA不同血清型的pfs高度保守,RA pfs基因的编码产物RA-Mtan在体外具有催化SAH的活性,RA-Mtan和禽致病性大肠杆菌的Lux S蛋白共同作用于底物SAH时,能产生有活性的AI-2,为进一步研究pfs对RA的调控作用提供参考。     

雌激素对中华鳖性腺分化及DMRT1、SOX9基因表达的影响

中华鳖（Pelodiscus sinensis）性别决定的方式一直存在较大的争议,分子机制更是不清楚。在大部分脊椎动物中,雌激素在性别决定和性腺分化中扮演重要的调控作用。实验通过对性别分化前胚胎进行雌二醇（E2）和芳香化酶抑制剂（AI）处理,研究雌激素在中华鳖性腺分化中的作用及机理。实验结果显示,与对照组（雌性比例49%）相比,E2处理组中雌性中华鳖仔鳖比例显著增加,高达92.3%;而在AI处理组中,雌性比例显著下调至13.1%。HE染色分析表明,ZZ（雄性）和ZW（雌性）胚胎分别经过E2和AI处理后,ZZ和ZW性腺结构呈现明显的雌性化和雄性化特征。同时,通过RT-PCR和免疫荧光染色发现,E2能显著降低雄性性别关键因子DMRT1和SOX9 mRNA和蛋白表达水平;AI则表现相反的调节作用。综上所述,雌激素通过抑制雄性性别关键因子DMRT1和SOX9的表达来抑制雄性分化,促进雌性分化,揭示雌激素在中华鳖雌性性别分化中起着重要的调控作用。       

H. pylori‐Induced Apoptosis in Human Gastric Cancer Cells Mediated via the Release of Apoptosis‐Inducing Factor from Mitochondria

Background and Aim: Our previous study of Helicobacter pylori‐induced apoptosis showed the involvement of Bcl‐2 family proteins and cytochrome c release from mitochondria. Here, we examine the release of other factors from mitochondria, such as apoptosis‐inducing factor (AIF), and upstream events involving caspase‐8 and Bid. Methods: Human gastric adenocarcinoma (AGS) cells were incubated with a cagA‐positive H. pylori strain for 0, 3, 6, and 24 hours and either total protein or cytoplasmic, nuclear, and mitochondrial membrane fractions were collected. Results: Proteins were immunoblotted for AIF, Bid, polyadenosine ribose polymerase (PARP), caspase‐8, and β‐catenin. H. pylori activated caspase‐8, caused PARP cleavage, and attenuated mitochondrial membrane potential. A time‐dependent decrease in β‐catenin protein expression was detected in cytoplasmic and nuclear extracts, coupled with a decrease in β‐actin. An increase in the cytoplasmic pool of AIF was seen as early as 3 hours after H. pylori exposure, and a concomitant increase was seen in nuclear AIF levels up to 6 hours. A band corresponding to full‐length Bid was seen in both the cytoplasmic and the nuclear fractions of controls, but not after H. pylori exposure. Active AIF staining was markedly increased in gastric mucosa from infected persons, compared to uninfected controls. Conclusion: H. pylori might trigger apoptosis in AGS cells via interaction with death receptors in the plasma membrane, leading to the cleavage of procaspase‐8, release of cytochrome c and AIF from mitochondria, and activation of subsequent downstream apoptotic events, as reported previously for chlorophyllin. This is consistent with AIF activation that was found in the gastric mucosa of humans infected with H. pylori. Hence, the balance between apoptosis and proliferation in these cells may be altered in response to injury caused by H. pylori infection, leading to an increased risk of cancer.     

集胞蓝藻PCC6803含疏水亚基的NAD（P）H脱氢酶亚复合体的分离

利用离子交换与凝胶过滤层析 ,从n dodecylβ D maltoside(DM)处理的集胞蓝藻SynechocystisPCC6 80 3细胞粗提液中 ,首次分离到两个包含NDH疏水亚基NdhA的亚复合体。酶活性分析表明 ,分离到的NDH亚复合体具有NADPH 氮蓝四唑 (NBT)氧化还原酶活性 ,以NADPH为电子供体可以还原铁氰化钾、二溴百里香醌 (DBMIB)、二氯酚靛酚 (DCPIP)、duroquinone以及UQ 0等质醌类电子受体。     

恶性肿瘤化疗所致院内感染31例分析

目的探讨恶性肿瘤患者化疗后发生院内感染的相关因素及防治措施。方法对31例恶性肿瘤患者化疗后发生的院内感染作回顾性分析。结果恶性肿瘤患者化疗后发生院内感染与中性粒细胞减少程度及持续时间有关,感染的部位以呼吸道为主,主要采用粒细胞集落刺激因子（G-CSF）及抗生素治疗。结论恶性肿瘤患者化疗所致院内感染与中性粒细胞减少程度及持续时间密切相关,合理使用G—CSF及抗生素是预防和控制感染的重要措施。     

枸杞花粉发育进程中花蕾和叶片物质代谢与育性的关系

以宁夏枸杞主栽品种'宁杞1号'的雄性不育株和可育株为研究材料,通过测定它们枝条生长速率,花粉不同发育时期花蕾和叶片的叶绿素、可溶性糖和脯氨酸含量以及硝酸还原酶活性,比较不育株与可育株在发育进程中物质代谢的差异.结果表明:在枸杞花粉发育进程中,不育株枝条生长速率快,花蕾和叶片的叶绿素含量高,而脯氨酸严重缺乏,可溶性糖含量和硝酸还原酶活性低,且各个发育阶段不育株和可育株均存在明显差异.可见,'宁杞1号'不育株物质代谢水平低,缺乏生理活性物质积累,使花粉发育有关基因的表达受到抑制,最终影响了其育性的正常表达.     

四川梅花鹿内脏系统初步解剖

对一只成年雌性四川梅花鹿内脏系统作了初步的观察和研究,其气管长440 mm;食道呈漏斗状,具伸缩性,粗细不等;胃属于反刍胃,包括瘤胃、网胃、瓣胃、皱胃,容积分别占全部胃室的80%、6%、6.5%、7.5%;肠道全长是体长的12.79倍,小肠较发达,全长11 661.36 mm,占肠道总长的58.8%,具有较发达的盲肠;卵巢较小,子宫属于双角子宫.     

Comparative in-vitro biodegradation studies of epoxy and its silicone blend by selected microbial consortia

A total of six bacterial isolates were developed into two consortia and tested for utilization of epoxy silicone blends (ESBs; % w/w: 3.0) and epoxy as the sole carbon source. In-vitro biodegradation studies in minimal broth revealed that higher biomass and more sustained growth of consortia were obtained in the presence of epoxy and/or ESBs when these were incubated under aerobic conditions for 15 days. Treated samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and simultaneous thermogravimetric–differential thermogravimetry–differential thermal analysis (TG–DTG–DTA), which indicated the breakage and formation of bonds in the polymer backbone. Moreover, a weight loss of 34.17 and 36.9% was found in epoxy and ESBs, respectively after 15 days of treatment with consortium-1. Further, in-vitro growth statistics study revealed more CFU count at mid-logarithmic phase in the presence of epoxy/ESBs unlikely to the absence of the polymers. However, the generation time was not affected. In the present study, consortium-1, comprising of Microbacterium sp., Pseudomonas putida and Bacterium Te 68R showed better biodegradation in comparison to consortium-2, wherein, P. putida and Pseudomonas aeruginosa were present. Overall, these results suggest that epoxy/ESBs polymers could be degraded by a biologically mediated process if a suitable consortium is used.     

镉、锌、铜胁迫对向日葵早期幼苗生长的影响

分析了3种重金属离子(Cd2+、Cu2+、Zn2+)对向日葵种子胚根伸长和早期幼苗生长的影响.结果表明,3种重金属离子对向日葵胚根伸长的抑制作用依次为:Cd2+>Cu2+>Zn2+.3种重金属胁迫明显降低了幼苗生长和叶绿素含量,并显著提高了H2O2水平.其中Cd2+胁迫引起幼苗H2O2爆发高于Cu2+和Zn2+胁迫.进一步分析植株抗氧化系统的变化发现,随着重金属离子浓度的增加,向日葵幼苗酶类抗氧化物质SOD和CAT的活性表现为先增加后降低的趋势;重金属胁迫提高了非酶类的抗氧化物质脯氨酸和GSH的含量.其中Cd2+和Zn2+胁迫对脯氨酸含量变化的影响大于Cu2+胁迫;而Cu2+胁迫对GSH含量变化的影响大于Cd2+和Zn2+胁迫.