Characterization and expression patterns of <Emphasis Type="Italic">let-7</Emphasis> microRNA in the silkworm (<Emphasis Type="Italic">Bombyx mori</Emphasis>)

Background  

lin-4 and let-7, the two founding members of heterochronic microRNA genes, are firstly confirmed in Caenorhabditis elegans to control the proper timing of developmental programs in a heterochronic pathway. let-7 has been thought to trigger the onset of adulthood across animal phyla. Ecdysone and Broad-Complex are required for the temporal expression of let-7 in Drosophila melanogaster. For a better understanding of the conservation and functions of let-7, we seek to explore how it is expressed in the silkworm (Bombyx mori).     

Knockout of the folate transporter <Emphasis Type="Italic">folt-1</Emphasis> causes germline and somatic defects in <Emphasis Type="Italic">C. elegans</Emphasis>

Background  

The C. elegans gene folt-1 is an ortholog of the human reduced folate carrier gene. The FOLT-1 protein has been shown to transport folate and to be involved in uptake of exogenous folate by worms. A knockout mutation of the gene, folt-1(ok1460), was shown to cause sterility, and here we investigate the source of the sterility and the effect of the folt-1 knockout on somatic function.     

Recombinant production of <Emphasis Type="Italic">Streptococcus equisimilis</Emphasis> streptokinase by <Emphasis Type="Italic">Streptomyces lividans</Emphasis>

Background  

Streptokinase (SK) is a potent plasminogen activator with widespread clinical use as a thrombolytic agent. It is naturally secreted by several strains of beta-haemolytic streptococci. The low yields obtained in SK production, lack of developed gene transfer methodology and the pathogenesis of its natural host have been the principal reasons to search for a recombinant source for this important therapeutic protein. We report here the expression and secretion of SK by the Gram-positive bacterium Streptomyces lividans. The structural gene encoding SK was fused to the Streptomyces venezuelae CBS762.70 subtilisin inhibitor (vsi) signal sequence or to the Streptomyces lividans xylanase C (xlnC) signal sequence. The native Vsi protein is translocated via the Sec pathway while the native XlnC protein uses the twin-arginine translocation (Tat) pathway.     

The <Emphasis Type="Italic">C. elegans Hox</Emphasis> gene <Emphasis Type="Italic">ceh-13</Emphasis> regulates cell migration and fusion in a non-colinear way. Implications for the early evolution of <Emphasis Type="Italic">Hox</Emphasis>clusters

Background  

Hox genes play a central role in axial patterning during animal development. They are clustered in the genome and specify cell fate in sequential domains along the anteroposterior (A-P) body axis in a conserved order that is co-linear with their relative genomic position. In the soil worm Caenorhabditis elegans, this striking rule of co-linearity is broken by the anterior Hox gene ceh-13, which is located between the two middle Hox paralogs, lin-39 and mab-5, within the loosely organized nematode Hox cluster. Despite its evolutionary and developmental significance, the functional consequence of this unusual genomic organization remains unresolved.     

Replicated associations of <Emphasis Type="Italic">TNFAIP3</Emphasis>, <Emphasis Type="Italic">TNIP1</Emphasis> and <Emphasis Type="Italic">ETS1</Emphasis> with systemic lupus erythematosus in a southwestern Chinese population

Introduction  

Recent genome-wide and candidate gene association studies in large numbers of systemic lupus erythematosus (SLE) patients have suggested approximately 30 susceptibility genes. These genes are involved in three types of biological processes, including immune complex processing, toll-like receptor function and type I interferon production, and immune signal transduction in lymphocytes, and they may contribute to the pathogenesis of SLE. To better understand the genetic risk factors of SLE, we investigated the associations of seven SLE susceptibility genes in a Chinese population, including FCGR3A, FCGR2A, TNFAIP3, TLR9, TREX1, ETS1 and TNIP1.     

<Emphasis Type="Italic">Erwinia carotovora</Emphasis> elicitors and <Emphasis Type="Italic">Botrytis cinerea</Emphasis> activate defense responses in <Emphasis Type="Italic">Physcomitrella patens</Emphasis>

Background  

Vascular plants respond to pathogens by activating a diverse array of defense mechanisms. Studies with these plants have provided a wealth of information on pathogen recognition, signal transduction and the activation of defense responses. However, very little is known about the infection and defense responses of the bryophyte, Physcomitrella patens, to well-studied phytopathogens. The purpose of this study was to determine: i) whether two representative broad host range pathogens, Erwinia carotovora ssp. carotovora (E.c. carotovora) and Botrytis cinerea (B. cinerea), could infect Physcomitrella, and ii) whether B. cinerea, elicitors of a harpin (HrpN) producing E.c. carotovora strain (SCC1) or a HrpN-negative strain (SCC3193), could cause disease symptoms and induce defense responses in Physcomitrella.     

<Emphasis Type="Italic">PGM2</Emphasis> overexpression improves anaerobic galactose fermentation in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Background  

In Saccharomyces cerevisiae galactose is initially metabolized through the Leloir pathway after which glucose 6-phosphate enters glycolysis. Galactose is controlled both by glucose repression and by galactose induction. The gene PGM2 encodes the last enzyme of the Leloir pathway, phosphoglucomutase 2 (Pgm2p), which catalyses the reversible conversion of glucose 1-phosphate to glucose 6-phosphate. Overexpression of PGM2 has previously been shown to enhance aerobic growth of S. cerevisiae in galactose medium.     

Transduplication resulted in the incorporation of two protein-coding sequences into the <Emphasis Type="Italic">Turmoil</Emphasis>-1 transposable element of <Emphasis Type="Italic">C. elegans</Emphasis>

   

Transposable elements may acquire unrelated gene fragments into their sequences in a process called transduplication. Transduplication of protein-coding genes is common in plants, but is unknown of in animals. Here, we report that the Turmoil-1 transposable element in C. elegans has incorporated two protein-coding sequences into its inverted terminal repeat (ITR) sequences. The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene. We further report that an open reading frame specific to C. elegans may have been created as a result of a Turmoil-1 insertion. Mutations at the 5' splice site of this open reading frame may have reactivated the transduplicated RRM motif.     

Molecular characterization of the <Emphasis Type="Italic">singed wings</Emphasis> locus of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Background  

Hormones frequently guide animal development via the induction of cascades of gene activities, whose products further amplify an initial hormonal stimulus. In Drosophila the transformation of the larva into the pupa and the subsequent metamorphosis to the adult stage is triggered by changes in the titer of the steroid hormone 20-hydroxyecdysone. singed wings (swi) is the only gene known in Drosophila melanogaster for which mutations specifically interrupt the transmission of the regulatory signal from early to late ecdysone inducible genes.     

Chemically defined medium and <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

Background  

C. elegans has been established as a powerful genetic system. Use of a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of use in large-scale growth and screening of animals.     

Manipulating the <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis> genome using <Emphasis Type="Italic">mariner</Emphasis> transposons

Tc1, one of the founding members of the Tc1/mariner transposon superfamily, was identified in the nematode Caenorhabditis elegans more than 25 years ago. Over the years, Tc1 and other endogenous mariner transposons became valuable tools for mutagenesis and targeted gene inactivation in C. elegans. However, transposition is naturally repressed in the C. elegans germline by an RNAi-like mechanism, necessitating the use of mutant strains in which transposition was globally derepressed, which causes drawbacks such as uncontrolled proliferation of the transposons in the genome and accumulation of background mutations. The more recent mobilization of the Drosophila mariner transposon Mos1 in the C. elegans germline circumvented the problems inherent to endogenous transposons. Mos1 transposition strictly depends on the expression of the Mos transposase, which can be controlled in the germline using inducible promoters. First, Mos1 can be used for insertional mutagenesis. The mobilization of Mos1 copies present on an extrachromosomal array results in the generation of a small number of Mos1 genomic insertions that can be rapidly cloned by inverse PCR. Second, Mos1 insertions can be used for genome engineering. Triggering the excision of a genomic Mos1 insertion causes a chromosomal break, which can be repaired by transgene-instructed gene conversion. This process is used to introduce specific changes in a given gene, such as point mutations, deletions or insertions of a tag, and to create single-copy transgenes.     

A proteomic view of <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis> caused by short-term hypoxic stress

Background  

The nematode Caenorhabditis elegans is both sensitive and tolerant to hypoxic stress, particularly when the evolutionarily conserved hypoxia response pathway HIF-1/EGL-9/VHL is involved. Hypoxia-induced changes in the expression of a number of genes have been analyzed using whole genome microarrays in C. elegans, but the changes at the protein level in response to hypoxic stress still remain unclear.     

Demonstration of IS<Emphasis Type="Italic">711</Emphasis> transposition in <Emphasis Type="Italic">Brucella ovis</Emphasis> and <Emphasis Type="Italic">Brucella pinnipedialis</Emphasis>

Background  

The Brucella genome contains an insertion sequence (IS) element called IS711 or IS6501, which is specific to the genus. The copy number of IS711 varies in the genome of the different Brucella species, ranging from 7 in B. abortus, B. melitensis and B. suis to more than 30 in B. ovis and in Brucella strains isolated from marine mammals. At present, there is no experimental evidence of transposition of IS711, but the occurrence of this element with a high copy number in some species, and the isolation of Brucella strains with "ectopic" copies of IS711 suggested that this IS could still transpose.     

<Emphasis Type="Italic">Vibrio</Emphasis> chromosomes share common history

Background  

While most gamma proteobacteria have a single circular chromosome, Vibrionales have two circular chromosomes. Horizontal gene transfer is common among Vibrios, and in light of this genetic mobility, it is an open question to what extent the two chromosomes themselves share a common history since their formation.