Project description:In this work we used stable isotope probing/proteomics to study uptake of carbon sources by members of the cyanobacterial consortium. The database for protein identification was obtained from assembled metagenomes.
Project description:Escherichia coli culture was subjected to two different types of nutritional scenarios, abundant carbon/ nitrogen sources and scarce carbon/nitrogen medium. Study revealed that scarce medium adapted culture were more tolerant to hydrogen peroxide than abundant medium.
Project description:Molecular hydrogen is a hopeful agent for oxidative stress-related and/or inflammatory disorders. However, the molecular mechanism for these therapeutic effects of hydrogen still remains to be fully elucidated. We examined whether molecular hydrogen alters gene expression levels in normal mouse livers by DNA microarray analysis. We identified 140 mouse genes that were upregulated (31 genes) or downregulated (109 genes) after three weeks of the inhalation of 2% hydrogen-containing air with oral intake of hydrogen-rich water. Ingenuity Pathway Analysis revealed that hydrogen influenced expression of NF-kB- and NFAT-regulated genes. Western blot analysis showed that hydrogen attenuated Erk, p38 MAPK, and NF-kB signaling in mouse livers.
Project description:Circular RNAs (circRNAs), which can function as regulators of gene expression, are formed by back-splicing of precursor mRNAs in the nucleus. circRNAs are predominantly localized in the cytoplasm, indicating that they must be exported from the nucleus. Here, we uncover a pathway specific for nuclear export of circular RNA. This pathway requires Ran-GTP, Exportin-2 and IGF2BP1. Enhancing the nuclear Ran-GTP gradient by depletion or chemical inhibition of the major protein exporter, CRM1, selectively increases nuclear export of circRNAs, while reducing the nuclear Ran-GTP gradient selectively blocks circRNA export. Analysis of nuclear circRNA binding proteins reveals that interaction of IGF2BP1 with circRNA is enhanced by Ran-GTP, whereas its interaction with linear RNA is inhibited by Ran-GTP. Depletion or knockout of Exportin-2 specifically inhibits nuclear export of circRNA, while formation of an Exportin-2 circRNA export complex requires Ran-GTP and IGF2BP1. Our findings demonstrate that adaptors such as IGF2BP1 that bind directly to circular RNAs recruit Exportin-2 to export circRNAs in a mechanism analogous to protein export, rather than mRNA export.
Project description:The piRNA pathway is a conserved small RNA-based immune system that protects animal germ cell genomes from the harmful effects of transposon mobilisation. In Drosophila ovaries, most piRNAs originate from dual-strand clusters, which generate piRNAs from both genomic strands. Dual-strand clusters use non-canonical transcription mechanisms. Although transcribed by RNA polymerase II, cluster transcripts lack splicing signatures and polyA tails. mRNA processing is important for general mRNA export mediated by Nuclear export factor 1. Although UAP56, a component of the transcription and export complex, has been implicated in piRNA precursor export, it remains unknown how dual-strand cluster transcripts are specifically targeted for piRNA biogenesis by export from the nucleus to cytoplasmic processing centers. Here we report that dual-strand cluster transcript export requires CG13741/Bootlegger and the Drosophila Nuclear export factor family protein, Nxf3. Bootlegger is specifically recruited to piRNA clusters and in turn brings Nxf3. We find that Nxf3 specifically binds to piRNA precursors and is essential for their export to piRNA biogenesis sites, a process that is critical for germline transposon silencing. Our data shed light on how dual-strand clusters bypass canonical mRNA features to be specifically exported via Nxf3, ensuring proper piRNA production.
Project description:Methanococcus maripaludis is a methanogenic Archaea that conserves energy from molecular hydrogen to reduce carbon dioxide to methane. Chemostat grown cultures limited for hydrogen, phosphate, or leucine were compared to determine the regulatory response to hydrogen limitation. This was done by comparing hydrogen limited cultures to both leucine limited and phosphate limited cultures. Slow and rapid growing samples limited for either hydrogen or phosphate were compared to determine the regulatory effects of growth rate. Keywords: archaea, hydrogen, leucine, phosphate, nutrient limitation, growth rate, methanogen
Project description:Purpose: Compare the transcriptomes of T. paralvinellae using RNA-Seq gene expression analyses to understand the physiology of this organism when it is grown on different carbon sources, under optimal and hydrogen stress conditions. Methods: T. paralvinellae was grown in triplicate at with either 0.5% maltose or 0.5% tryptone to investigate its catabolic pathways when grown on a sugar and peptides, respectively. It was also grown on 1% formate to determine the effect of formate on cell growth, metabolite production, and gene expression. It was also grown separately on maltose or tryptone media as before, except with hydrogen in the media to examine the effects of hydrogen inhibition. The cells remaining in the 2-liter bioreactor were concentrated by centrifugation. The resulting cell pellets were resuspended in TRIzol (Invitrogen) and total RNA was extracted using a Direct-zol RNA extraction kit (Zymo). RNA quantity was determined with Qubit fluorometry. RNA integrity was checked by a bioanalyzer and a Nanodrop spectrometer. Genewiz sequencing facilities performed rRNA removal, library construction, multiplexing and sequence the RNA with HiSeq2500, 2×100 Paired-End. We aligned the RNAseq reads to T. paralvinellae genome (STAR) and assigned aligned sequence reads to genomic features (featureCounts). We then quantified transcriptome and reported pairwise significant genes that are differentially expressed by DESeq available under Bioconductor (www.bioconductor.org) on Galaxy platform and in R. Results: Sequencing depths ranged from 29,974,378 to 45,240,342 sequences, with a mean of 38,990,002 and a median of 38,951,352 reads per sample. Of 2,138 genes annotated in the T. paralvinellae genome, 2084 transcripts were detected by RNA-Seq.Of the 2084 genes detected by transcriptomics, hydrogen stress caused only 48 genes to be differentially regulated (log2FC > 1, P < 0.05) with maltose and tryptone carbon sources. These included mostly genes associated with formate-dependent metabolism and transporters. The upregulated genes upon growth under H2 stress conditions indicate intrinsic formate production via formate hydrogen lyase and format secretion.
Project description:Circular RNAs (circRNAs), which are increasingly being implicated in a variety of functions in normal and cancerous cells1-5, are formed by back-splicing of precursor mRNAs in the nucleus6-10. circRNAs are predom¬inantly localized in the cytoplasm, indicating that they must be exported from the nucleus. Here, we uncover a pathway specific for nuclear export of circular RNA. This pathway requires Ran-GTP, Exportin-2 and IGF2BP1. Enhancing the nuclear Ran-GTP gradient by depletion or chemical inhibition of the major protein exporter, CRM1, selectively increases nuclear export of circRNAs, while reducing the nuclear Ran-GTP gradient selectively blocks circRNA export. Depletion or knockout of Exportin-2 specifically inhibits nuclear export of circRNA. Analysis of nuclear circRNA binding proteins reveals that interaction of IGF2BP1 with circRNA is enhanced by Ran-GTP. Formation of circRNA export complexes in the nucleus is promoted by Ran-GTP through its interactions with IGF2BP1, Exportin-2 and circRNA. Our findings demonstrate that adaptors such as IGF2BP1 that bind directly to circular RNAs recruit Ran-GTP and Exportin-2 to export circRNAs in a mechanism analogous to protein export, rather than mRNA export.
Project description:Alternative polyadenylation (APA) produces mRNA isoforms with different 3’UTR lengths. Previous studied indicated that 3’ end processing and mRNA nuclear export are intertwined in gene regulation. Here, we show that mRNA export factors generally facilitate usage of distal cleavage and polyadenylation sites (PASs), leading to expression of long 3’UTR isoforms. By focusing on the export receptor NXF1, which exhibits the most potent effect on APA in this study, we reveal a number of gene features that impact NXF1-dependent APA, including 3’UTR size, gene size and AT content. Surprisingly, downregulation of NXF1 results in accumulation of RNAP II at the 3’ end of genes, correlating with its role in APA regulation. Moreover, we show that NXF1 cooperates with CFI-68 to facilitate nuclear export of long 3’UTR isoform with UGUA motifs. Together, our work reveals several important roles of NXF1 in coordinating RNAPII distribution, 3’ end processing, and mRNA export of long 3’UTR transcripts, implicating NXF1 as the nexus of gene expression regulation.
Project description:The nuclear export of messenger RNAs (mRNAs) is intimately coupled to their synthesis. pre-mRNAs assemble into dynamic ribonucleoparticles as they are being transcribed, processed and exported. The role of ubiquitylation in this process is increasingly recognized as the ubiquitylation of many key players have been shown to affect mRNA nuclear export. While a few E3 ligases have been shown to regulate nuclear export, evidence for deubiquitylases is currently lacking. Here, we identified the deubiquitylase Ubp15 as a regulator of nuclear export in Saccharomyces cerevisiae. Ubp15 interacts both with RNA polymerase II and with the nuclear pore complex, and its deletion reverts the nuclear export defect of mutants of the E3 ligase Rsp5. The deletion of UBP15 leads to hyper-ubiquitylation of the main nuclear export receptor Mex67 and affects its association with THO, a complex coupling transcription to mRNA processing and involved in the recruitment of mRNA export factors to nascent transcripts. Collectively, our data support a role for Ubp15 in coupling transcription to mRNA export.