Responses of the ecological characteristics and antioxidant enzyme activities in Rotaria rotatoria to UV-B radiation

Hydrobiologia - UV-B radiation is an increasing threat to aquatic organisms and also a potential driving force for zooplankton population dynamics. To explore the ecological effects of UVR on...     

Features of Pro-σK Important for Cleavage by SpoIVFB,an Intramembrane Metalloprotease

Intramembrane proteases regulate diverse processes by cleaving substrates within a transmembrane segment or near the membrane surface. Bacillus subtilis SpoIVFB is an intramembrane metalloprotease that cleaves Pro-σ^K during sporulation. To elucidate features of Pro-σ^K important for cleavage by SpoIVFB, coexpression of the two proteins in Escherichia coli was used along with cell fractionation. In the absence of SpoIVFB, a portion of the Pro-σ^K was peripherally membrane associated. This portion was not observed in the presence of SpoIVFB, suggesting that it serves as the substrate. Deletion of Pro-σ^K residues 2 to 8, addition of residues at its N terminus, or certain single-residue substitutions near the cleavage site impaired cleavage. Certain multiresidue substitutions near the cleavage site changed the position of cleavage, revealing preferences for a small residue preceding the cleavage site N-terminally (i.e., at the P1 position) and a hydrophobic residue at the second position following the cleavage site C-terminally (i.e., P2′). These features appear to be conserved among Pro-σ^K orthologs. SpoIVFB did not tolerate an aromatic residue at P1 or P2′ of Pro-σ^K. A Lys residue at P3′ of Pro-σ^K could not be replaced with Ala unless a Lys was provided farther C-terminally (e.g., at P9′). α-Helix-destabilizing residues near the cleavage site were not crucial for SpoIVFB to cleave Pro-σ^K. The preferences and tolerances of SpoIVFB are somewhat different from those of other intramembrane metalloproteases, perhaps reflecting differences in the interaction of the substrate with the membrane and the enzyme.     

Neuroprotective effects of (E)-3,4-diacetoxystyryl sulfone and sulfoxide derivatives in vitro models of Parkinson's disease

(E)-3,4-dihydroxystyryl aralkyl sulfones and sulfoxides have been reported as novel multifunctional neuroprotective agents in previous studies, which as phenolic compounds display antioxidative and antineuroinflammatory properties. To further enhance the neuroprotective effects and study structure-activity relationship of the derivatives, we synthesized their acetylated derivatives, (E)-3,4-diacetoxystyryl sulfones and sulfoxides, and examined their neuroprotective effects in vitro models of Parkinson’s disease. The results indicate that (E)-3,4-diacetoxystyryl sulfones and sulfoxides can significantly inhibit kinds of neuron cell injury induced by toxicities, including 6-OHDA, NO, and H₂O₂. More important, they show higher antineuroinflammatory properties and similar antioxidative properties to corresponding un-acetylated compounds. Thus, we suggest that (E)-3,4-diacetoxystyryl sulfones and sulfoxides may have potential for the treatment of neurodegenerative disorders, especially Parkinson’s disease.     

Shotgun proteomic analysis of mulberry dwarf phytoplasma

Background  

Mulberry dwarf (MD), which is caused by phytoplasma, is one of the most serious infectious diseases of mulberry. Phytoplasmas have been associated with diseases in several hundred plant species. The inability to culture phytoplasmas in vitro has hindered their characterization at the molecular level. Though the complete genomes of two phytoplasmas have been published, little information has been obtained about the proteome of phytoplasma. Therefore, the proteomic information of phytoplasmas would be useful to elucidate the functional mechanisms of phytoplasma in many biological processes.     

植物内生细菌的侵染定殖规律研究进展

详细综述了植物内生细菌的侵染定殖过程,即吸附、侵入、定殖三个阶段。着重阐述了对植物内生细菌的定殖检测方法,包括抗生素标记法、免疫学方法、基因标记法及特异性寡核苷酸片段标记法等。另外,对植物内生细菌的来源及定殖影响因子也进行了系统讨论,并对未来植物内生细菌定殖研究前景作了展望。     

Autophagic flux is essential for the downregulation of <Emphasis Type="Italic">D</Emphasis>-dopachrome tautomerase by atractylenolide I to ameliorate intestinal adenoma formation

Colorectal cancer is generally believed to progress through an adenoma - carcinoma sequence. Adenomatous polyposis coli (APC) mutations serve as the initiating event in adenoma formation. The Apc^Min/+ mouse harbors a mutation in the APC gene, which is similar or identical to the mutation found in individuals with familial adenomatous polyposis and 70% of all sporadic CRC cases. Autophagy is a constitutive process required for proper cellular homeostasis. However, its role in intestinal adenoma formation is still controversial. Atractylenolide I (AT1) is a sesquiterpenoid that possesses various clinically relevant properties such as anti-tumor and anti-inflammatory activities. The role of AT1 on adenoma formation was tested in Apc^Min/+ mice and its underlying mechanism in regulating autophagy was documented. D-dopachrome tautomerase (D-DT) was identified as a potential target of AT1 by an proteomics-based approach. The effects of p53 modification on autophgic flux was monitored in p53^?/? and p53^+/+ HCT116 cells. Small interfering RNA was used to investigate the function of Atg7 and D-DT on autophagy programme induce by AT1. AT1 effectively reduced the formation of adenoma and downregulated the tumorigenic proteins in Apc^Min/+ mice. Importantly, AT1 stimulated autophagic flux through downregulating acetylation of p53. Activation of Sirt1 by AT1 was essential for the deacetylation of p53 and downregulation of D-DT. The lowered expression of COX-2 and β-catenin by AT1 were partly recovered by Atg7 knockdown. AT1 activates autophagy machinery to downregulate D-DT and reduce intestinal adenoma formation. This discovery provides evidence in vivo and in vitro that inducing autophagy by natural products maybe a potential therapy to ameliorate colorectal adenoma formation.     

镜湖萼花臂尾轮虫（Brachionus calyciflorus）种群遗传多样性的季节变化

运用随机扩增多态DNA（RAPD）技术研究了于2005年春季和夏季采自芜湖市镜湖的萼花臂尾轮虫（Brachionus calyciflorus）种群基因组DNA多态性。从44个随机引物中筛选出10个谱带清晰、重复性好的引物。10个引物共检测到76个位点,其中65个位点显多态性,多态位点比例（P）为85.5%。对RAPD扩增结果进行聚类分析,基于遗传距离指数构建了萼花臂尾轮虫的UPGMA和ME系统树。经计算,各克隆平均遗传距离指数为0.5219,春季种群内遗传距离指数（0.4416）大于夏季种群内遗传距离指数（0.4304）;两季节种群间遗传距离指数为0.6010,明显大于季节种群内遗传距离指数。16个克隆分别聚在2个主要簇群中,在UPGMA系统树中,春季种群和夏季种群明显分聚在两个主要支系中;而在ME树中,除了夏季Su2克隆和春季种群聚到一个支系外,其它夏季种群则聚在一个独立支系中。上述结果表明,春季种群和夏季种群在遗传上具有较大的差异;镜湖萼花臂尾轮虫种群存在着明显的季节更替,而Su2克隆可能是春季和夏季种群间的过渡。     

稻田土壤－作物－家畜系统中氮的循环研究

本文用Ｎ￣（１５）标记水稻和绿肥研究了稻田土壤－作物－家畜系统中氮的循环。Ｎ￣（１５）标记稻草喂羊,羊体回收饲料稻草Ｎ３１．１６％,羊粪２８．２６％,羊尿５．７２％,总回收６５．１４％,损失３４．８６％。将羊粪尿单施,稻谷回收饲料稻草Ｎ３．１９％,水稻全株回收４．８２％,土壤残留１９．００％,损失１０．１４％。故羊体、水稻及土壤残留共回收饲料稻草Ｎ５４．９８％．将羊粪与尿素配施,则饲料稻草Ｎ的总回收率为５５．８８％。Ｎ￣（１５）标记绿肥喂猪;猪体回收饲料绿肥Ｎ２３．５１％．猪粪２３．８５％,猪尿２８．７６％,总回收率７６．１２％,损失率２３．８８％。将猪粪、尿还田,稻谷回收饲料绿肥Ｎ６．６９％,水稻全株回收１０．０５％,土壤残留１９．１７％,故猪体、水稻和土壤残留共回收饲料绿肥Ｎ５２．７３％,将猪粪与尿素配施,则饲料绿肥Ｎ的总回收率为５２．７５％。