Molecular evolution in hypotrichous ciliates: Sequence of the small subunit ribosomal RNA genes fromOnychodromus quadricornutus andOxytricha granulifera (Oxytrichidae,Hypotrichida, Ciliophora)

Summary The small subunit ribosomal RNA (16S-like rRNA) coding regions of the hypotrichous ciliatesOnychodromus quadricornutus andOxytricha granulifera were amplified using polymerase chain reaction techniques. Complete sequences were determined for the amplified genes and compared to those of other ciliated protozoa. In phylogenetic trees inferred using distance matrix methods oxytrichids are not seen as a cohesive phylogenetic group.Oxytricha nova is most closely related toStylonychia pustulata in a lineage that also includesO. quadricornutus. This phylogeny contradicts phylogenetic schemes in whichOnychodromus is considered to be a primitive hypotrichous ciliate and suggests thatO. nova was misidentified as members of the genusOxytricha.     

Phylogenetic relationships within the class Oligohymenophorea,phylum Cilophora,inferred from the complete small subunit rRNA gene sequences ofColpidium campylum,Glaucoma chattoni,andOpisthonecta henneguyi

Summary Phylogenetic relationships within the class Oligohymenophorea, phylum Ciliophora, were investigated by determining the complete small subunit rRNA (SSrRNA) gene sequences for the hymenostomesColpidium campylum, Glaucoma chattoni, and the peritrichOpisthonecta henneguyi. The affiliations of the oligohymenophoreans were assessed using both distance matrix (DM) and maximum parsimony (MP) analyses. Variations do exist in the phylogenies created by the two methods. However, the basic tree topologies are consistent. In both the DM and MP analyses the hymenostomes (C. campylum, G. chattoni, and the tetrahymenas) all form a very tight group associated with the peritrichO. henneguyi. TheTetrahymena lineage was monophyletic whereasColpidium andGlaucoma were more closely related to each other than either was to the tetrahymenas. The monophyly of the genusTetrahymena in the present analysis supports the phylogenies determined from morphological data and molecular sequence data from the histone H3II/H4II region of the genome. The perplexing and controversial phylogenetic position of the peritrichs is once again depicted in the present analysis. The distinctiveness of the peritrichOpisthonecta from both hymenostome and nassophorean ciliates based on evolutionary distances suggests that the elevation of the peritrichs to a higher taxonomic rank should be reconsidered.     

恒河猴外周血及肾组织SV40病毒基因分析

SV40即猿猴病毒40(simian virus 40),是DNA肿瘤病毒的原型代表,其基因结构为共价闭合环状双股DNA分子,标准参考株SV40-776含5243个核甘酸,不同分离株bp数略有差异.     

MyD88-independent activation of a novel actin-Cdc42/Rac pathway is required for Toll-like receptor-stimulated phagocytosis

Phagocytosis and subsequent degradation of pathogens by macrophages play a pivotal role in host innate immune responses to microbial infection. Recent studies have shown that Toll-like receptors （TLRs） play an important role in promoting the clearance of bacteria by up-regulating the phagocytic activity of macrophages. However, information regarding the signaling mechanism of TLR-mediated phagocytosis is still limited. Here, we provide evidence that the stimulation of TLR4 with LPS leads to activation of multiple signaling pathways including MAP kinases, phosphatidylinositide 3-kinase （PI3K）, and small GTPases in the murine macrophage-like cell line RAW264.7. Specific inhibition of Cdc42/Rac or p38 MAP kinase, but not PI3K, reduced TLR4-induced phagocytosis of bacteria. Moreover, we have found that either inhibition of actin polymerization by cytochalasin D or the knockdown of actin by RNAi markedly reduced the activation of Cdc42 and Rac by LPS. TLR4-induced activation of Cdc42 and Rac appears to be independent of MyD88. Taken together, our results described a novel actin-Cdc42/Rac pathway through which TLRs can specifically provoke phagocytosis.     

Immune regulatory functions of DOCK family proteins in health and disease

DOCK proteins constitute a family of evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho family of GTPases. Although DOCK family proteins do not contain the Dbl homology domain typically found in GEFs, they mediate the GTP–GDP exchange reaction through DHR-2 domain. Accumulating evidence indicates that the DOCK proteins act as major GEFs in varied biological settings. For example, DOCK2, which is predominantly expressed in hematopoietic cells, regulates migration and activation of leukocytes through Rac activation. On the other hand, it was recently reported that mutations of DOCK8, another member of the DOCK family proteins, cause a combined immunodeficiency syndrome in humans. This article reviews the structure, functions and signaling of DOCK2 and DOCK8, especially focusing on their roles in immune responses.     

Analysis of ribosomal DNA restriction patterns in the genusKluyveromyces

Riboprinting was used to determine the relationships among strains belonging to 15 species of the genusKluyveromyces. The small subunit ribosomal RNA gene (SSU rDNA) was amplified using the Polymerase Chain Reaction (PCR) and subjected to a battery of nine restriction enzymes. Similarity coefficients between strains were calculated based on shared and unique restriction fragments. Cluster analysis revealed three major groups that generally correlated with previously reported relationships based on other molecular data. Variations in SSU rDNA restriction fragments may be used for differentiation of theKluyveromyces strains included in this study.The U.S. Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Rab23 研究进展

Rab23为小GTP结合蛋白,是Ras超家族Rab家族成员,其突变可引起小鼠开脑综合征(open brain syndrome),因此又称为opb基因.它是Sonic hedgehog信号通路的负调控因子,在不同肿瘤中发挥不同作用,并参与机体组织器官的发育和分化.它可能通过转运细胞内蛋白发挥相关作用.     

森林生态系统年净初级生产力和生境复杂度对小型兽类物种多样性影响

本研究主要探讨黄龙自然保护区森林生态系统年净初级生产力水平和栖息地复杂程度对小型兽类物种多样性的影响。将调查区按海拔高度分为4 个调查点,每点的年净初级生产力水平各不相同,分别为: 24.9 MJ / (m²·a) ; 21.5 MJ / (m²·a) ; 17.5 MJ / (m²·a) 和14.1 MJ / (m²·a) 。在选择调查点时,同时考虑栖息地复杂程度,在生产力水平较高的调查点选择栖息地复杂程度较低的地点,而在生产力较低的调查点选择栖息地复杂程度较高的地点调查,以便分析森林生态系统年净初级生产力水平与栖息地复杂程度对小型兽类物种多样性的影响。采用鼠铗捕获小型兽类。结果表明,小型兽类物种多样性与森林生态系统年净初级生产力水平有密切关系,随着海拔升高,森林生态系统年净初级生产力的降低,所捕获的小型兽类生物量随之降低,其物种多样性也随之下降。小型兽类物种多样性也与栖息地复杂程度有关,森林生态系统年净初级生产力水平在一定范围内,大于17.5 MJ / (m²·a) ,栖息地复杂度的增加可以降低年净初级生产力水平对小型兽类物种多样性的影响。然而,森林生态系统年净初级生产力水平降低到一定程度时,小于14.1 MJ / (m²·a) ,生产力水平则为影响小型兽类物种多样性的主要因子。此外,小型兽类的生物量与森林生态系统年净初级生产力和栖息地复杂程度也有类似的关系。