The perpetuation and epidemic recurrence of communicable diseases in human populations

Recurrence of communicable diseases is a looming threat for human populations. Factors explaining the recurrences are partially known, involving demographics, biology, and complex relationships with the environment, but no comprehensive theory exists today. Here, we review some recent results obtained in modelling studies with a view to understanding better the mechanisms of perpetuation. Factors intrinsic to the interaction of pathogen and host have regained interest in this respect, especially with multiple pathogen and multiple population interactions. Extrinsic factors, including pure demography and environmental forcing are also strong predictors. With increasingly detailed data available, large-scale integrated models will help sorting out the multiple influences on recurrence.     

1990年和2019年中国心血管疾病负担及危险因素研究

摘要 目的：分析1990年和2019年中国心血管发病、死亡和疾病负担情况。方法：利用2019年全球疾病负担数据库,分析总人群、不同年龄组间1990年和2019年我国心血管发病、死亡、伤残调整寿命年（DALY）、过早死亡损失寿命年(YLL)和伤残损失寿命年(YLD)。并对心血管进行危险因素归因分析。结果：2019年中国心血管发病人数为1234.1万 ,发病率为867.65/10万,较1990年分别增长了132.82%和93.75% 。2019年死亡人数458.43万 ,死亡率为322.30/10万,较1990年分别上升了89.12%和57.39%。2019年中国心血管DALY、YLD和YLL分别为9193.31万人年、1038.39万人年和8154.93万人年。较1990年分别上升了50.07%、146.82%和45.48%。2019年发病率、死亡率和DALY率最高的年龄组均为＞70年龄组,分别为4646.78/10万、3057.82/10万和52696.68/10万。中国心血管归因于代谢危险导致的死亡人数、DALY和YLL最多,分别为3272924人、67112754人年和59934426人年。结论：我国心血管的疾病负担在1990-2019年间有较大增长,应采取积极的预防措施以减轻心血管的疾病负担。     

马先蒿属一中国新记录种——陈塘马先蒿

于西藏喜马拉雅南坡的陈塘沟开展植物多样性调查过程中,发现一种在《中国植物志》中未记录的马先蒿属（Pedicularis）植物。通过文献查阅和详细的形态学比较,确定其为中国新记录种Pedicularis tamurensis T. Yamaz.,为其新拟中文名称：陈塘马先蒿。该种以前仅发现于尼泊尔,现也发现于中国西藏自治区日喀则市定结县陈塘镇。此新记录种生长于海拔约2?900 m的冷杉（Abies fabri (Mast.) Craib）林下,与光唇马先蒿（Pedicularis fletcheri P. C. Tsoong）相似,主要识别特征为：叶对生,两面均密生短毛,羽状全裂至深裂;花序总状,花白色,盔瓣呈镰刀状弯弓,中间渐狭成喙,顶端2裂,下唇完全包围盔瓣。本文对陈塘马先蒿进行了详细的形态描述,介绍了其分布信息,并提供彩色图片便于鉴别。该新记录种的发现更新了国产马先蒿属植物的资料,丰富了中国植物多样性的内容。     

Birth and evolutionary history of a human minisatellite

One of the most exciting challenges in human biology is the understanding of how our genome was constructed during evolution. Here we explore the evolutionary history of the low polymorphic human minisatellite MsH42 and its flanking sequences. We show that the evolutionary birth of MsH42 took place within an intron, early in primate lineage evolution, more than 40 MYA. Then, single base-pair changes and duplications/deletions of repeat blocks by mispairing were probably the main forces governing the generation of this minisatellite and its polymorphism throughout primate evolution. Moreover, we detected several phylogenetic footprints at both sides of MsH42. We believe that our findings will contribute to the understanding of low-variability minisatellite evolution.     

Catabolite regulation of the cytochrome c550-encoding Bacillus subtilis cccA gene

In Gram-positive bacteria, catabolite control protein A (CcpA)-mediated catabolite repression or activation regulates not only the expression of a great number of catabolic operons, but also the synthesis of enzymes of central metabolic pathways. We found that a constituent of the Bacillus subtilis respiratory chain, the small cytochrome c550 encoded by the cccA gene, was also submitted to catabolite repression. Similar to most catabolite-repressed genes and operons, the Bacillus subtilis cccA gene contains a potential catabolite response element cre, an operator site recognized by CcpA. The presumed cre overlaps the -35 region of the cccA promoter. Strains carrying a cccA'-IacZ fusion formed blue colonies when grown on rich solid medium, whereas white colonies were obtained when glucose was present. beta-Galactosidase assays with cells grown in rich medium confirmed the repressive effect of glucose on cccA'-lacZ expression. Introduction of a ccpA or hprK mutation or of a mutation affecting the presumed cccA cre relieved the repressive effect of glucose during late log phase. An additional glucose repression mechanism was activated during stationary phase, which was not relieved by the ccpA, hprK or cre mutations. An interaction of the repressor/corepressor complex (CcpA/seryl-phosphorylated HPr (P-Ser-HPr)) with the cccA cre could be demonstrated by gel shift experiments. By contrast, a DNA fragment carrying mutations in the presumed cccA cre was barely shifted by the CcpA/P-Ser-HPr complex. In footprinting experiments, the region corresponding to the presumed cccA cre was specifically protected in the presence of the CcpA/P-Ser-HPr complex.     

Selection of ergot alkaloid producers by induced mutagenesis

Using the induced mutagenesis technique, A series of genetically modified Claviceps sp. VKM F-2609 strains that display high levels of agroclavine and elymoclavine synthesis were selected by induced mutagenesis. Compared to the parent strain, c106 displayed a 40-fold higher level of agroclavine synthesis, and c66 displayed an eightfold higher level of elymoclavine synthesis. The levels of synthesis of other alkaloids were decreased in these strains. The effects of various carbohydrates on the strain growth and ergot alkaloid biosynthesis was then investigated in both the parent strain and c106. The largest amount of agroclavine was synthesized by c106 strain growing on a medium with maltose.     

Factors contributing to roquefortine yield variability during cultivation of penicillium roquefortii

Variability in the roquefortine yield was shown to be associated with its consumption by the mycelium during isolation of the end product, which depended on temperature, time of culture liquid storage, and biomass concentration. This was also related to the presence in chloroform of chlorocarbonic acid ethyl ester that reacted with roquefortine.     

Optimization of the medium and cultivation conditions of Penicillium roquefortii f39 producing the diketopiperazine alkaloid roquefortine

We optimized the medium for cultivation of Penicillium roquefortii f39, a producer of roquefortine. In this medium, the roquefortine yield increased 1.5-2-fold. The increase in roquefortine content was associated with high biomass yield, but not with an increase in biosynthetic activity of the mycelium. Direct correlation was found between extracellular roquefortine concentration and amount of the inoculum. The introduction of sucrose into the growth medium allowed us to increase the concentration of roquefortine during fermentation to 90 mg/l.