Cryptosporidium parvum: identification of a new surface adhesion protein on sporozoite and oocyst by screening of a phage-display cDNA library

Cryptosporidium parvum is a significant cause of diarrheal disease worldwide. The specific molecules that mediate C. parvum-host interaction and the molecular mechanisms involved in the pathogenesis are unknown. In this study we described a novel phage display method to identify surface adhesion proteins of C. parvum. A cDNA library of the sporozoite and oocyst stages of C. parvum expressed on the surface of T7 phage was screened with intestinal epithelial cells (IECs) from the newborn Cryptosporidium-free Holstein calves. Proteins that selectively and specifically bound to IECs were then enriched using a multi-step panning procedure. Two proteins of C. parvum were selected, one was previously reported (p23), which was an important surface adhesion protein; the other was a novel surface adherence protein (CP12). Sequence analysis showed that CP12 has a N-terminal signal peptide, a transmembrane region, a N-glycosylation site, a casein kinase II phosphorylation site and two N-myristoylation sites. Immunofluorescence assay (IFA) using antibody specific for rCP12 demonstrated that the antibody can specifically bind the surface of sporozoite and oocyst, especially apical region of sporozoite. The surface localization of CP12 and its involvement in the host-parasite interaction suggest that it may serve as an effective target for specific preventive and therapeutic measures for cryptosporidiosis.     

Influenza virus matrix protein M1 interacts with SLD5 to block host cell cycle

Influenza virus matrix 1 protein (M1) is highly conserved and plays essential roles at many stages of virus life cycle. Here, we used a yeast two‐hybrid system to identify the host protein SLD5, a component of the GINS complex, which is essential for the initiation of DNA replication in eukaryotic cells, as a new M1 interacting protein. M1 from several different influenza virus strains all interacted with SLD5. Overexpression of SLD5 suppressed influenza virus replication. Transient, stable, or inducible expression of M1 induced host cell cycle blockade at G0/G1 phase. Moreover, SLD5 partially rescued M1 expression‐ or influenza virus infection‐induced G0/G1 phase accumulation in cell lines and primary mouse embryonic fibroblasts. Importantly, SLD5 transgenic mice exhibited higher resistance and improved lung epithelial regeneration after virus infection compared with wild‐type mice. Therefore, influenza virus M1 blocks host cell cycle process by interacting with SLD5. Our finding reveals the multifunctional nature of M1 and provides new insight for understanding influenza virus–host interaction.     

<Emphasis Type="Italic">Sphingobacterium bambusae</Emphasis> sp. nov., isolated from soil of bamboo plantation

A Gram-negative, non-motile, non-spore-forming bacterial strain designated IBFC2009^T was isolated from soil of a bamboo plantation. The strain could grow at 11°C∼39°C, pH 6.0–9.0, and in the presence of 0∼5% NaCl. Based on 16S rRNA gene sequence analysis, Strain IBFC2009^T belonged to the genus Sphingobacterium and showed the highest sequence similarity of 94.6% (S. composti T5-12^T) with the type strains within the genus. The major fatty acids were summed feature 3 (iso-C_15:0 2-OH and/or C_16:1 ω7c, 34.4%), iso-C_15:0 (22.4%), C_16:0 3-OH (15.2%), and iso-C_17:0 3-OH (12.8%). The G+C content of the genomic DNA was 41.0 mol%. According to the phenotypic and genotypic characteristics, Strain IBFC2009^T should represent a novel species of the genus Sphingobacterium, for which the name Sphingobacterium bambusae sp. nov. is proposed. The type strain is IBFC2009^T (=CCTCC AB 209162^T =KCTC 22814^T).     

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.     

Identification and characterization of 177 unreported genes associated with liver regeneration

The mammalian liver has a very strong regeneration capacity after partial hepatectomy (PH). To further learn the genes participating in the liver regeneration (LR), 551 cDNAs selected from subtracted cDNA libraries of the regenerating rat liver were screened by microarray, and their expression profiles were studied by cluster and generalization analyses. Among them, 177 genes were identified unreported and up-or down-regulated more than twofold at one or more time points after PH, of which 62 genes were down-regulated to less than 0.5; 99 genes were up-regulated to 2-10 folds, and 16 genes were either up- or down-regulated at different time points during LR. By using BLAST and GENSCAN, these genes were located on responsible chromosomes with 131 genes on the long arms of the chromosomes. The cluster and generalization analyses showed that the gene expression profiles are similar in 2 and 4, 12 and 16, 96 and 144 h respectively after PH, suggesting that the actions of the genes expressed in the same profiles are similar, and those expressed in different profiles have less similarity. However, the types,characteristics and functions of the 177 genes remain to be further studied.     

TBX1, a DiGeorge syndrome candidate gene, is inhibited by retinoic acid

Both retinoic acid (RA) and Tbx1 are definitively indispensable for the development of the pharyngeal arches. The defects produced by a loss of Tbx1 highly resemble those induced by hyper- and hypo-RA. Based on these similarities, the effects of RA on Tbx1 expression pattern were explored during pharyngeal arch development in zebrafish. Whole-mount in situ hybridization and real-time quantitative PCR were used. Zebrafish embryos were treated with 5 x 10(-8)mol/L and 10(-7)mol/L RA at 12.5 hours post fertilization for 1.5 hours, respectively. Whole-mount in situ hybridization showed that Tbx1 was expressed in the cardiac region, pharyngeal arch and otic vesicle between 24 hpf and 72 hpf in zebrafish. Tbx1 expression was obviously reduced, even lost, in the pharyngeal arch and outflow tract in RA treated groups. Real-time quantitative PCR analysis showed that Tbx1 expression rose to a peak level at 36 hpf in wild type group. Repression of Tbx1 expression was most evident at 36 hpf, 24 hours after RA treatment. 10(-7 )mol/L RA caused a more severe effect on the Tbx1 expression level than 5 x 10(-8)mol/L RA.The results suggested that RA could produce an altered Tbx1 expression pattern in zebrafish. In addition, RA could repress Tbx1 expression in a dose-dependent manner.     

尖吻蝮(Agkistrodon acutus)蛇毒凝血酶样成分的研究——Ⅲ.蛇毒凝血酶止血效应的研究

将纯化得到的蛇毒凝血酶(TLE_3、TLE_4),经家兔体内实验表明,2—3凝血酶单位/kg体重剂量能显著地使家兔全血凝血时间缩短1/3—1/2。药后1小时即有促凝作用,以2—4小时凝血(止血)效应最强,12小时已消失。与Holleman, W. H.等自美洲矛头蝮蛇毒中得到的蛇毒凝血酶(Hemocoagulase)相似。经家兔及家犬实验性创伤止血实验表明,对创伤出血有止血作用。