利用宏基因组学分析壬基酚对剩余污泥厌氧发酵产酸的影响

研究了环境雌激素壬基酚（NP）对剩余污泥厌氧发酵产酸的影响,并利用宏基因组测序手段分析影响机制。NP促进污泥厌氧发酵产酸,随NP含量的提高,该促进作用呈先增加后减少的趋势。当NP含量为200 mg·kg^-1干污泥时,污泥发酵产生的短链脂肪酸（SCFAs）达最大值,为空白组SCFAs产量的2倍,乙酸产量为空白组的3倍。基于宏基因组学的机理研究表明,NP导致不利于SCFAs积累的耗酸微生物有所削减,产酸微生物大量积累。NP存在时,以葡萄糖为底物的糖酵解、以氨基酸为底物的脱氨基和以脂肪酸为底物的β氧化过程功能基因相对丰度提高;单糖和氨基酸等有机底物由胞外向胞内运输的腺苷三磷酸结合盒转运蛋白、运输至胞内的有机底物向SCFAs代谢转化的双组分系统及胞内产生的SCFAs外排转运蛋白的相关功能基因丰度大幅提高。最后,NP引起了与细胞生长和保护机制密切相关的群体感应调控的生物膜合成基因丰度显著提升。     

不同摄入量小米对小鼠肠道菌群和短链脂肪酸的影响

摄入一定量杂粮可降低一些慢性代谢疾病的发病率,但目前杂粮摄入量没有统一的标准,尚不清楚杂粮摄入过多是否会对健康产生不良影响。以小米添加量为20%、40%、60%、80%的饲料喂养3周龄C57BL/6J小鼠,持续12周,采用自动血生化分析仪、16S rRNA高通量基因测序、气相色谱-质谱联用仪分析了不同摄入量小米对小鼠血脂水平、肠道菌群和粪便短链脂肪酸的影响。结果发现,80%摄入量的小米显著增加了小鼠血清的总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇的水平,同时增加了肠道丙酸、丁酸、异丁酸和戊酸的含量。肠道菌群分析结果表明,所有小米干预组的拟杆菌门(Bacteroidota)、Muribaculaceae的丰度上升,厚壁菌门(Firmicutes)、放线菌门(Actinobacteriota)、乳杆菌科(Lactobacillaceae)、双歧杆菌属 (Bifidobacterium)的丰度下降。摄入不同添加量小米的小鼠肠道菌群组成具有较大差异,其中20%小米摄入量组的小鼠菌群中显著富集了另枝菌属(Alistipes)、副拟杆菌属(Parabacteroides)、肠杆菌属(Enterorhabdus),而80%摄入量小米显著降低了小鼠菌群中的粪杆菌属(Faecalibaculum)、布劳特氏菌属(Blautia)和罗氏菌属(Roseburia)的丰度。研究结果表明,20%摄入量的小米就能有效调节小鼠肠道菌群,而过高摄入量(80%)的小米使小鼠血脂水平升高,降低了肠道菌群的多样性和均匀度以及有益菌的丰度,所以要理性看待杂粮的营养价值,避免过量摄入。     

天然氨基酸中氢键的量子化学研究

用从头计算法优化了20种天然氨基酸正、负、偶极离子.计算结果表明,α-NH2上的氮原子可以和羧基氧原子形成氢键,通过N1-H2…O3氢键的生成,原子N1、H3、O4、C4、C5形成了五元环.从正离子、负离子到偶极离子,氢键强度逐渐减小.侧链原子对氢键也有影响:正离子的侧链除苏氨酸和丝氨酸外,其它氨基酸不对氢键构成影响;负离子氢键受侧链的影响较大;而偶极离子中氢键基本不受侧链的影响.     

从天然氨基酸到咪唑衍生物

天然氨基酸是较好的手性来源．在碱性条件下与乙二醛、甲醛经过缩合反应生成了（S）-2-（咪唑-1-基）羧酸钠，再在甲醇中和氯化亚砜反应制得手性咪唑羧酸甲酯．进一步以二胺为桥联剂，经直接胺解获得双咪唑化合物．对所制化合物进行了结构表征．     

GC-MS联用鉴别植物油中的特征脂肪酸

采用氢氧化钾—甲醇衍生化体系，以正庚烷为提取剂，用气相色谱—质谱联用仪对棕榈油、调和油、花生油和豆油中的特征脂肪酸进行了鉴别。     

超强酸催化有机酸衍生化分离分析研究

固体超强酸具有较高的反应活性和较好的选择性．文章研究了玫瑰茄油在固体超强酸催化下合成高级脂肪酸脂．再采用GC—MS对其中的脂肪酸进行了定性和定量分析．玫瑰茄油中各种脂肪酸的质量分数分别为棕榈酸18%；硬脂酸30%；油酸38%；亚油酸14%。     

Sexual dimorphism in the defensive secretion of a carabid beetle

Summary The defensive secretions of male and femaleOodes americanus display striking qualitative differences. Altogether 13 carboxylic acids were identified in the secretions of the two sexes. Methacrylic, crotonic, and tiglic acids are produced exclusively by the female; the male lacks these unsaturated components, but produces their saturated analogs. 2-Methylbutyric acid is a major component produced by both sexes. Shared components also include hexanoic, (E)-2-hexenoic, benzoic, and (E)-2-octenoic acid, of which the latter two had not previously been reported from carabid beetles.Paper no. 98 in the series Defense Mechanisms of Arthropods; no. 97 is by Smedley et al., J. Lepid. Soc., in press.     

胶束水溶液代替有机溶剂分离氨基酸

以胶束水溶液为展开剂，用纸色谱法分离了氨基酸类化合物，胶束水溶液阶廉，安全，无毒，不燃，易生物降解，可供替有机溶剂进入实验课教学。     

Thiyl radicals in biosystems: effects on lipid structures and metabolisms

Thiyl radicals are intermediates of enzyme- and radical-driven biochemical processes, and their potential as reactive species in the biological environment has been somehow underestimated. From organic chemistry, however, it is known that thiyl radicals isomerize the double bonds of unsaturated fatty acids to a mixture with very dominating trans isomers. Recently, this reaction has been particularly studied for biosystems, focusing on the effect of thiyl radicals on the natural all-cis double bonds of unsaturated phospholipids, which undergo a conversion to the unnatural trans form. In this paper we report briefly the role of thiyl radicals in biosystems, describe the main features of the radical-induced cis-trans isomerization process under both in vitro and in vivo conditions, and reflect on some consequences for membrane structures, lipid metabolism and enzymatic reactions.Received 29 October 2004; received after revision 3 December 2004; accepted 4 January 2005