Loss of autophagy diminishes pancreatic beta cell mass and function with resultant hyperglycemia

Autophagy is a cellular degradation-recycling system for aggregated proteins and damaged organelles. Although dysregulated autophagy is implicated in various diseases including neurodegeneration, its role in pancreatic beta cells and glucose homeostasis has not been described. We produced mice with beta cell-specific deletion of Atg7 (autophagy-related 7). Atg7 mutant mice showed impaired glucose tolerance and decreased serum insulin level. beta cell mass and pancreatic insulin content were reduced because of increased apoptosis and decreased proliferation of beta cells. Physiological studies showed reduced basal and glucose-stimulated insulin secretion and impaired glucose-induced cytosolic Ca2+ transients in autophagy-deficient beta cells. Morphologic analysis revealed accumulation of ubiquitinated protein aggregates colocalized with p62, which was accompanied by mitochondrial swelling, endoplasmic reticulum distension, and vacuolar changes in beta cells. These results suggest that autophagy is necessary to maintain structure, mass and function of pancreatic beta cells, and its impairment causes insulin deficiency and hyperglycemia because of abnormal turnover and function of cellular organelles.     

Role of Amphipathic Helix of a Herpesviral Protein in Membrane Deformation and T Cell Receptor Downregulation

Lipid rafts are membrane microdomains that function as platforms for signal transduction and membrane trafficking. Tyrosine kinase interacting protein (Tip) of T lymphotropic Herpesvirus saimiri (HVS) is targeted to lipid rafts in T cells and downregulates TCR and CD4 surface expression. Here, we report that the membrane-proximal amphipathic helix preceding Tip''s transmembrane (TM) domain mediates lipid raft localization and membrane deformation. In turn, this motif directs Tip''s lysosomal trafficking and selective TCR downregulation. The amphipathic helix binds to the negatively charged lipids and induces liposome tubulation, the TM domain mediates oligomerization, and cooperation of the membrane-proximal helix with the TM domain is sufficient for localization to lipid rafts and lysosomal compartments, especially the mutivesicular bodies. These findings suggest that the membrane-proximal amphipathic helix and TM domain provide HVS Tip with the unique ability to deform the cellular membranes in lipid rafts and to downregulate TCRs potentially through MVB formation.     

中国东部武夷山风景区苔藓中的缓步动物

记述了采自中国东部福建省武夷山风景区苔藓中的缓步动物11种,包括:日本棘影熊虫Echiniscus japonicus Morikawa,1951中国东部新纪录种;结痂棘影熊虫Echiniscus scabrospinesus Fontoura,1982中国东部新纪录种;华美假棘影熊虫Pseudechiniscus facettalis Petersen,1951中国东部新纪录种;迟缓小斑熊虫Milnesium tardigradum(Doyère,1840);埃卡门大生熊虫Macrobiotus ariekammensis Weglarska,1965中国东部新纪录种;节值大生熊虫,模式亚种Macrobiotus harms worthi harmsworthi Murray,1907;华丽大生熊虫Macrobiotus richtersi Murray,1911;陆栖大生熊虫Macrobiotus terricola Miheli,1949;异常拉玛熊虫Ramazzottius anomalus(Ramazzotti,1962)中国新纪录种;肥曲拉玛熊虫Ramazzottius oberhaeuseri(Doyère,1840);黄色具矛熊虫Doryphoribius flavus(Iharos,1966)中国东部新纪录种。所有的标本均保存于中国科学院水生生物研究所。     

中国牛蛭属一新种记述(吻蛭目,医蛭科)

报道了采自云南省景东县的牛蛭属Poecilobdella Blanchard,18931新种。由于新种总体环数为99环,生殖孔分别在30(Ⅺ)与38(ⅩⅢ)环内,两孔相隔7环;肛门在99环与尾吸盘交界线上;附睾呈卵圆形,精管膨腔呈梨形并且为前者的1/3大小;阴道盲囊呈圆球形,阴道管粗短且无阴道柄。因此与本属中所有的已知种均不相同。     

重组马g-干扰素抗病毒活性测定及单克隆抗体抑制活性鉴定

为了测定大肠杆菌和杆状病毒表达的重组马g-干扰素是否具有抗病毒活性, 利用这两种干扰素处理马胎肾细胞(EFK-78), 然后接种表达绿色荧光蛋白(GFP)的重组水泡性口炎病毒(VSV*GFP), 观察干扰素对病毒表达GFP的抑制, 测出其抗病毒活性单位分别为1×103 AU/mL、1×105 AU/mL。评价了制备的九株抗重组马g-干扰素单克隆抗体是否可抑制重组马g-干扰素抗病毒活性, 证实其中一株可中和重组马g-干扰素的抗病毒活性。结果表明: 杆状病毒表达的马g-干扰素具有较高的抗病毒活性, 其活性可被一株制备的抗重组马g-干扰素单克隆抗体抑制; 首次获得原核表达的具有抗病毒活性的马g-干扰素。     

Enhanced performance in prediction of protein active sites with THEMATICS and support vector machines

Theoretical microscopic titration curves (THEMATICS) is a computational method for the identification of active sites in proteins through deviations in computed titration behavior of ionizable residues. While the sensitivity to catalytic sites is high, the previously reported sensitivity to catalytic residues was not as high, about 50%. Here THEMATICS is combined with support vector machines (SVM) to improve sensitivity for catalytic residue prediction from protein 3D structure alone. For a test set of 64 proteins taken from the Catalytic Site Atlas (CSA), the average recall rate for annotated catalytic residues is 61%; good precision is maintained selecting only 4% of all residues. The average false positive rate, using the CSA annotations is only 3.2%, far lower than other 3D-structure-based methods. THEMATICS-SVM returns higher precision, lower false positive rate, and better overall performance, compared with other 3D-structure-based methods. Comparison is also made with the latest machine learning methods that are based on both sequence alignments and 3D structures. For annotated sets of well-characterized enzymes, THEMATICS-SVM performance compares very favorably with methods that utilize sequence homology. However, since THEMATICS depends only on the 3D structure of the query protein, no decline in performance is expected when applied to novel folds, proteins with few sequence homologues, or even orphan sequences. An extension of the method to predict non-ionizable catalytic residues is also presented. THEMATICS-SVM predicts a local network of ionizable residues with strong interactions between protonation events; this appears to be a special feature of enzyme active sites.     

Analysis of several serum enzymes and blood urea nitrogen of swainsonine–HSA immunized goats

Locoweeds cause significant livestock poisoning and economic loss all over the world. The purpose of this study was to evaluate the immune effect of locoweed toxin, swainsonine (SW), and human serum albumin (HSA) immunoconjugate (SW–HSA) on goats. Twenty four Sannon goats were randomly separated into immune control group, immune poisoning group I, immune poisoning group II and poisoning control group. Immune control group, immune poisoning group I and II were first vaccinated with SW–HSA immunoconjugate. Then, the poisoning control group, immune poisoning group I and II were fed with 10.0 g/kg BW/d dry powder of Oxytropis kansuensis Bunge in every morning and the duration of poisoning was 80 days. The immune control group was supplied with an alfalfa-based diet. Blood samples of these experimental animals were collected every 7 days after poisoning, and the serum enzymes α-mannosidase (AMA), lactate dehydrogenase (LDH), alkaline phosphatase (AKP), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and blood urea nitrogen (BUN) were analyzed. Comparing with the poisoning control group, the changes of serum LDH, AKP, AST, AMA and BUN level of the two immune groups (I and II) were delayed 28, 14, 28, 21, 14 days, respectively, which indicated that SW–HSA immunoconjugate could prevent tissues containing BUN and these serum enzymes of the experimental animals from Oxytropis kansuensis Bunge injuring during these days. In the whole study, SW–HSA immunoconjugate and swainsonine did not influence serum ALT levels of the experimental goats.     

Preterm birth without progesterone withdrawal in 15-hydroxyprostaglandin dehydrogenase hypomorphic mice

Parturition is a complex mammalian physiological process whose fundamental determinants have remained elusive. The increasing incidence of human preterm birth, a leading cause of infant mortality, highlights the importance of further understanding mechanisms regulating the timing of birth. Parturition is initiated in most nonprimate mammals, including mice, through a decrease in circulating progesterone caused by elevated prostaglandins. In humans, other higher primates, and guinea pigs, no consistent decrease in circulating progesterone occurs before the onset of labor. The divergence in endocrine control of labor initiation between most mammals compared with the great apes and guinea pigs gives rise to the question: how could a mechanism for the initiation of labor not requiring the withdrawal of progesterone evolve? Here, we genetically modulate prostaglandin signaling to determine the role of prostaglandin catabolism in the timing of birth. We find spontaneous preterm labor in the absence of progesterone withdrawal in 15-hydroxyprostaglandin dehydrogenase hypomorphic mice. The onset of labor in these hypomorphic mice is preceded by prematurely increased concentrations of prostaglandin E(2) and F(2alpha). Moreover, genetic crosses demonstrate a role for fetal genotype in birth timing. Together, these findings demonstrate a 15-hydroxyprostaglandin dehydrogenase-dependent shift in the physiology of murine parturition to one resembling the physiology of higher primates. Thus, endocrine control of labor has the capacity to plastically adapt to changes in genetically determined prostaglandin signals.     

协同刺激分子与疾病

在T细胞表面受体中,除TCR外,协同刺激分子在调节T细胞的免疫反应中起关键性作用,目前较熟悉的协同刺激分子及其配体有：CD40／CD40L、B7—1／B7-2-CD28／CTLA-4、ICOS—B7RP-1。最近人们又发现了CD2-LFA3、CD5-CD5L、4—1BB／4—1BBL、HAS等新的协同刺激分子组合,它们在器官移植、肿瘤治疗、自身免疫病的治疗方面有重要作用;在基础研究中则可用于T细胞与B细胞分化、活化机制、抗原递呈、协同刺激机制、免疫耐受、移植排异反应和自体免疫等的研究。     

Trichoderma harzianum及其近缘种的分子系统学研究

Thichoderma harzianum是木霉属内最常见的一个“集合种”。本研究对来源不同的T.harzianum及其相似种的46个菌株进行了ITS序列测定,将其ITSl—5．8S—ITS2序列与来自EMBL的参考菌株的序列进行比较,并进行系统发育分析,此外对其中的18个菌株进行了RAPD多态性分析,试图明确T.harzianum的多样性以及与其相似种之间的关系。ITS结果表明,T.harzianum及其相似种可分成2个群(A、B)：A群由T.hamatum、T.asperellum、T.at-roviride、T.koningii和T.viride组成,并形成2个分支,表明T.viride和T.koningii、T.atroviride的亲缘关系较近,而与T.hamatum、T.asperellum较远;B群由T.spirale、T.hamatum、T.inhamatum、T.harzianum和T.anam。Hypocrea vinosa组成,并形成6个分支。T.inhamatum可分成2个群(Ti1、Ti2)、T.harzianum至少可分成5个群(Thl、Th2、Th4、Th5、Th6)。结果还表明T.hamatum的遗传差异较大,T.hamatum的模式菌株归属于A群,而其他的T.hamatum的菌株归属于B群。RAPD结果与ITS的结果基本一致。