Characteristic male urine microbiomes associate with asymptomatic sexually transmitted infection

Background

The microbiome of the male urogenital tract is poorly described but it has been suggested that bacterial colonization of the male urethra might impact risk of sexually transmitted infection (STI). Previous cultivation-dependent studies showed that a variety of non-pathogenic bacteria colonize the urethra but did not thoroughly characterize these microbiomes or establish links between the compositions of urethral microbiomes and STI.

Methodology/Findings

Here, we used 16S rRNA PCR and sequencing to identify bacteria in urine specimens collected from men who lacked symptoms of urethral inflammation but who differed in status for STI. All of the urine samples contained multiple bacterial genera and many contained taxa that colonize the human vagina. Uncultivated bacteria associated with female genital tract pathology were abundant in specimens from men who had STI.

Conclusions

Urine microbiomes from men with STI were dominated by fastidious, anaerobic and uncultivated bacteria. The same taxa were rare in STI negative individuals. Our findings suggest that the composition of male urine microbiomes is related to STI.     

大白鼠上丘脑片深层部突触传递和LTP的研究

在大白鼠上丘脑片深层部的中层或深层给电刺激、分别在径向对应的深层或中层,记录到诱发的突触后场电位.以100Hz、1秒的强直刺激首次在上丘的深层部引出了长时程突触增强(LTP).N-甲基-D-天冬氨酸(NMDA)受体的选择性拮抗剂2-氨基-5-磷酸戊酸盐(APV)对LTP的阻断效应表明,NMDA受体不仅对上丘深层部LTP的产生有作用.而且也与LTP的维持有关.突触后场电位的幅度受APV或兴奋性氨基酸受体的非选择性拮抗剂犬尿喹啉酸(KYNA)的作用而减小,受γ-氨基丁酸(GABA)A型受体的选择性拮抗剂荷包牡丹碱(Bicu)的作用而增加,表明谷氨酸能神经递质在上丘深层部的兴奋性突触传递中起着重要作用,并且这些突触传递也受到GABA能抑制性突触的调节.     

Selenium Promotes the Growth and Photosynthesis of Tomato Seedlings Under Salt Stress by Enhancing Chloroplast Antioxidant Defense System

Tomato (Lycopersicon esculentum Miller) cv. Jiahe No. 9 (a salinity-resistant cultivar) and cv. Shuangfeng 87-5 (a salinity-sensitive cultivar) were used as experimental materials to investigate the effects of exogenous selenium (Na₂SeO₃ 0.05 mM) on plant growth, chlorophyll fluorescence, photosynthetic rate, and antioxidative metabolism of chloroplasts in tomato seedlings under NaCl (100 mM) stress. Salt stress significantly inhibited plant growth, net photosynthetic rate (P _n), maximum quantum yield of PSII (F _v/F _m), actual photochemical efficiency of PSII (Φ _PSII), photochemical quenching coefficient (q _P), and non-photochemical quenching coefficient (q _N) of both cultivars, whereas application of Se reversed the negative effects of salt stress. Furthermore, application of Se significantly decreased the levels of hydrogen peroxide (H₂O₂) and malondialdehyde. Application of Se increased the activities of superoxidase dismutase, glutathione reductase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione peroxidase, and thioredoxin reductase, and the contents of ascorbate, glutathione (GSH) and NADPH, and the ratios of GSH/GSSH, AsA/DHA, and NADPH/ NADP⁺ in the salt-stressed chloroplasts of both cultivars. These results suggest that Se alleviates salt-induced oxidative stress through regulating the antioxidant defense systems in the chloroplasts of tomato seedlings, which is associated with the improvement of the photochemical efficiency of PSII, thereby maintaining higher photosynthetic rates. In addition, the salt tolerance of Jiahe No. 9 is closely related with high reactive oxygen species scavenging activity and reducing power levels in the chloroplasts.     

植物细胞核雄性不育基因研究进展

植物雄性不育既是研究植物生殖生物学重要的植物学性状也是研究作物杂种优势利用重要的农艺性状,在遗传和分子生物学中具有重要地位。以模式植物拟南芥和水稻为主,对植物雄性不育的控制基因和相关分子机理已有众多进展,按照花药发育时期和雄性败育的表现形式可以归纳为减数分裂异常、胼胝质代谢异常、绒毡层发育异常、花粉壁发育异常、花药开裂异常,以及其它类型的雄性不育。在不育相关基因中,导致胼胝质代谢异常、绒毡层发育异常和花粉壁发育异常的基因往往表现一因多效,一个相关基因的突变会产生复合表型。关于植物雄性不育相关基因的研究表明,雄性器官和小孢子形成过程中的任何相关基因的改变,均可导致雄性不育的产生。本文总结了植物核基因雄性不育的研究进展,以期促进不同物种间雄性不育基因的比较分析,使植物雄性不育研究更加深入。     

Stereoselective Toxicity and Metabolism of Lactofen in Primary Hepatocytes From Rat

The stereoselective metabolism of lactofen in primary rat hepatocytes was studied using a chiral high‐performance liquid chromatographic (HPLC) method. Rac‐lactofen and its two enantiomers, S‐(+)‐ and R‐(?)‐lactofen, as well as two of its major metabolites, acifluorfen, S‐(+)‐ and R‐(?)‐desethyl lactofen, were used as substrates,. The single and joint cytotoxicity of parent compounds and the metabolites were assessed by coincubation with rat hepatocytes as target cells. Cytotoxicity was determined by the methyl tetrazolium (MTT) assay. In hepatocyte incubations, S‐(+)‐lactofen was degraded more rapidly than R‐(?)‐lactofen, and a stereospecific formation of S‐(+)‐desethyl lactofen was detected. Metabolism of lactofen to desethyl lactofen was processed with the retention of configuration, and the achiral compound, acifluorfen, was the shared metabolite generated from both S‐(+)‐ and R‐(?)‐lactofen. There was no chiral conversion of lactofen or desethyl lactofen enantiomers during the incubation. For the cytotoxicity research, the calculated EC₅₀ values indicated that when being applied individually, the parent compound was less toxic than its metabolites, while the combination with metabolites enhanced its cytotoxic effects. The data presented here would be helpful for a more comprehensive assessment of the ecotoxicological and environmental risks of lactofen. Chirality 25:743–750, 2013. © 2013 Wiley Periodicals, Inc.     

Structural changes of the myofibrillar proteins in common carp (Cyprinus carpio) muscle exposed to a hydroxyl radical-generating system

Oxidation is a leading cause for quality deterioration during processing and storage of food. The objective of the present study was to examine the sensitivity of common carp (Cyprinus carpio) myofibrillar protein (MP) to oxidising radicals produced by a hydroxyl radical-generating system. Both structural and functional changes of common carp MP were evaluated. With increasing H₂O₂ concentrations and oxidation time, the protein carbonyl content, surface hydrophobicity and turbidity of MP increased (P < 0.05), while total sulfhydryl groups decreased (P < 0.05). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed protein polymerisation in oxidised MP. The oxidative process destroyed (P < 0.05) the texture (springiness and hardness) of MP gels and decreased their water-binding capacity and whiteness. The thermal gelation profile analysis indicated that oxidation led to a great reduction in the elasticity of samples. Taken together, proteins are susceptible to free radical attack, and oxidative stress had a detrimental effect on protein structure and the general functionality of MP.     

A chlorophyll-deficient rice mutant with impaired chlorophyllide esterification in chlorophyll biosynthesis

Chlorophyll (Chl) synthase catalyzes esterification of chlorophyllide to complete the last step of Chl biosynthesis. Although the Chl synthases and the corresponding genes from various organisms have been well characterized, Chl synthase mutants have not yet been reported in higher plants. In this study, a rice (Oryza Sativa) Chl-deficient mutant, yellow-green leaf1 (ygl1), was isolated, which showed yellow-green leaves in young plants with decreased Chl synthesis, increased level of tetrapyrrole intermediates, and delayed chloroplast development. Genetic analysis demonstrated that the phenotype of ygl1 was caused by a recessive mutation in a nuclear gene. The ygl1 locus was mapped to chromosome 5 and isolated by map-based cloning. Sequence analysis revealed that it encodes the Chl synthase and its identity was verified by transgenic complementation. A missense mutation was found in a highly conserved residue of YGL1 in the ygl1 mutant, resulting in reduction of the enzymatic activity. YGL1 is constitutively expressed in all tissues, and its expression is not significantly affected in the ygl1 mutant. Interestingly, the mRNA expression of the cab1R gene encoding the Chl a/b-binding protein was severely suppressed in the ygl1 mutant. Moreover, the expression of some nuclear genes associated with Chl biosynthesis or chloroplast development was also affected in ygl1 seedlings. These results indicate that the expression of nuclear genes encoding various chloroplast proteins might be feedback regulated by the level of Chl or Chl precursors.