BAmSA: Visualising transmembrane regions in protein complexes using biotinylated amphipols and electron microscopy

Membrane protein (MP) complexes play key roles in all living cells. Their structural characterisation is hampered by difficulties in purifying and crystallising them. Recent progress in electron microscopy (EM) have revolutionised the field, not only by providing higher-resolution structures for previously characterised MPs but also by yielding first glimpses into the structure of larger and more challenging complexes, such as bacterial secretion systems. However, the resolution of pioneering EM structures may be difficult and their interpretation requires clues regarding the overall organisation of the complexes. In this context, we present BAmSA, a new method for localising transmembrane (TM) regions in MP complexes, using a general procedure that allows tagging them without resorting to neither genetic nor chemical modification. Labels bound to TM regions can be visualised directly on raw negative-stain EM images, on class averages, or on three-dimensional reconstructions, providing a novel strategy to explore the organisation of MP complexes.     

包头泉山金矿浸矿酸性微生物群落优势度变化的比较研究

【目的】研究不同矿石组成对微生物群落结构的影响。【方法】选取包头泉山金矿的酸性矿坑水(Acid mine drainage,AMD)对4种不同组成的矿石样品进行浸矿,采用16S rRNA-PCR和RFLP相结合的方法,研究浸矿前后浸矿微生物种群优势度的变化情况。【结果】所选取的3个酸性矿坑水考查点之间浸矿微生物的种类及数量相似度较大,浸矿微生物结构相对变化度不大。H71和F11相对其他两个样品的群落结构差异较大,而J72和S71几乎一样,说明在钾长型和石英型矿石的选择压力下,浸矿微生物的被选择趋势是大致相同的。【结论】浸矿前后样品中浸矿微生物的系统发育分析结果表明,所考查的克隆子的序列可分为两大分支:Acidithiobacillus菌属和一个相对独立的菌属,且这两个分支内部菌株之间的发育距离较近。     

A note on the estimation of selective values from recaptures of marked animals when selection pressures remain constant over time

An equation is given for the estimation of selective values from data obtained by mark-recapture experiments, assuming that selective pressures remain constant while the experiments are carried out. The equation does not have an explicit solution but can readily be solved using a trial-and-error method. The use of the equation is illustrated on some data reported byKettlewell et al. (1969) from an experiment involving typica and edda morphs of the moth Amathes glareosa. It is found that the edda morph apparently had a selective advantage of about 12% per day compared to the typica morph and that this is significantly different from zero. Using another methodKettlewell concluded that the selective advantage of the edda morph was only 7% and that this was not statistically significant.     

A new coryneform hydrogen bacterium: Corynebacterium autotrophicum strain 7 C

A slime-free mutant was isolated from Corynebacterium autotrophicum strain 7 C. The mutant appeared in a substrate (fructose) limited chemostat culture. No significant differences between wildtype and mutant were detected with respect to pigmentation, to growth rate, and respiratory rate at varying substrate (fructose) concentrations. During growth in chemostat culture the wildtype/mutant ratio present in the inoculum was maintained for weeks. The results do not explain the selection of the mutant in the substrate limited chemostat culture.The slime is a polysaccharide containing glucose, mannose and galactose; the uronic acid present was not identified. Copious amounts are produced from fructose, less from lactate or during autotrophic growth. The slime is not reutilized.     

单细胞凝胶电泳应用研究进展

单细胞凝胶电泳技术是被广泛使用的检测DNA损伤的技术,其具有灵敏度高、简便、经济、快速等各种优点。在近30年来,该技术广泛被应用于遗传毒理、环境监测、医学诊断等研究及各类实验证实方面。近些年单细胞凝胶电泳与荧光原位杂交等其他技术相结合后更是拓宽了它的应用范围,本文主要介绍了单细胞凝胶电泳的原理及优劣,并重点阐明了其在遗传毒理学、细胞凋亡、环境监测、群体生物学、临床诊断与治疗,生物信息学领域上的应用,并讨论了它的发展前景。     

细菌生物被膜检测与分析方法

细菌生物被膜(Biofilm,BF)由物体表面集聚生长的微生物群落和自身分泌的胞外物质构成,是造成细菌产生多重耐药性的原因之一。可靠、简单和快速的BF检测方法有助于有效预防和治疗相关疾病。基于不同原理的检测与分析方法已广泛用于BF研究中,本文从生物学方法、物理方法和化学方法等方面对BF检测方法进行总结,重点阐述显微镜技术在BF检测中的应用。并介绍了近年来发展的拉曼光谱、质谱成像、MALDI-TOF-MS等新技术,同时比较其优点和局限性,以便研究者找到最合适和最新的研究方法。     

灭活益生菌的研究进展

益生菌是一种对人体有益的细菌,含生理活性菌或死细胞(包括代谢产物与细胞组成)。随着对益生菌研究的深入,人们发现灭活状态的益生菌在多个方面较活菌具备更大的优势。研究灭活益生菌,主要采用的灭活方法有热灭活、γ-射线灭活、紫外线灭活和酸灭活。结合近年来对灭活益生菌研究的情况,总结出灭活益生菌在增强免疫、抗肿瘤、抑制病源微生物、吸附有害物、缓解过敏症状、调整肠道菌群、预防龋齿和降低血清胆固醇等方面均具有效性。灭活益生菌目前已被广泛的应用于食品、医药卫生和饲料等多个领域。     

Twenty years of melanoma in Victoria,Queensland, and South Australia (1997 – 2016)

BackgroundGiven the high incidence of melanoma in Australia alongside high mortality with later stage disease, we investigated the populations and locations most at risk, to optimise public health activities in areas where intervention is most needed. This study examines trends and identifies significant prognostic factors and potential disparities in incidence, mortality and survival between population groups in Victoria, Queensland and South Australia.MethodsThe analysis includes data from the population-based cancer registries of the three states over a twenty-year period (1997–2016). Age-standardized and age-specific incidence rates were calculated, and long-term trends analysed using Joinpoint Regression. Five-year relative survival estimates for the study population were calculated using the cohort method and multivariable flexible parametric survival models were applied for each jurisdiction to calculate adjusted excess mortality hazard ratios for the key characteristics.ResultsThere were more males with melanoma than females in all the three states. Over 60% of the cases occurred in the 40–74 years age group. Most melanomas had a Breslow thickness less than or equal to 1.0 mm. For males, Victoria and Queensland had a statistically significant increasing trend whereas in South Australia there was a decreasing trend. For females, the incidence rate trend was stable in Victoria but significantly decreasing in South Australia. In Queensland there was an increasing and statistically significant trend from 2006 to 2016. Across all three states there was a reducing incidence rate in the youngest cohort, stabilizing incidence in the 40–59-year-old age group, and increasing in the oldest cohorts. Five-year relative survival decreased with increasing age and with Breslow thickness across all three jurisdictions. Males had between 43%− 46% excess mortality compared to females in all the three states. There was higher risk with increasing age and Breslow thickness, with the largest risk among the 75 + age group and those with a Breslow thickness of > 4 mm.ConclusionIt is the first time that data from these three registries has been analysed together in a uniform way, covering more than half of the Australian population. This study compares the epidemiology of melanoma across three states and provides a better understanding of trends and factors affecting outcome for Australians with melanoma. While there has been some improvement in aspects of incidence and mortality, this has not been evenly achieved across Australia.