Project description:Murine long-term hematopoietic stem cells (HSCs), short-term HSCs and multipotent progenitor cells (MPPs) were isolated from bone marrow and expression profiled on Affy chips. The behavior of maternal-specific imprinting genes, particularly in the H19-Igf2 locus, was focused on, to see if any might be involved in maintaining quiescence of long-term stem cells.
Project description:Long-term hematopoietic stem cells (HSCs), short-term HSCs and multipotent progenitor cells (MPPs) were isolated from bone marrow of four mouse strains (WT, H19-deletion, Igf1r-deletion, and double-deletion) and expression profiled with RNAseq. The behavior of the transcriptomes, and in particular the imprinted genes, was analyzed to see what might be involved in maintaining quiescence of long-term stem cells, and how H19 and Igf1r affected the expression of imprinted genes. Transcriptional profiling data of the same cells have been deposited in ArrayExpress under accession number E-MTAB-1644 (http://wwwdev.ebi.ac.uk/arrayexpress/experiments/E-MTAB-1644/).
Project description:Accurate translation of mRNAs into functional proteins is a fundamental process in all living organisms. In bacteria, in the early stage of translation elongation, peptidyl-tRNAs (pep-tRNAs) with short nascent chains frequently dissociate from the ribosome (pep-tRNA drop-off). The dissociated pep-tRNAs are deacylated and recycled by peptidyl-tRNA hydrolase (PTH), which is an essential enzyme in bacteria. Here, we establish a highly sensitive method for direct profiling of pep-tRNAs using RNA isolation method and mass spectrometry. We isolated each tRNA species with peptide from Escherichia coli pthts cells using reciprocal circulating chromatography and precisely analyzed their nascent peptides. As a result, we successfully detected 703 peptides consisted of 402 cognate peptides and 301 non-cognate peptides with single amino-acid substitution. Detailed analysis of individual pep-tRNAs revealed that most of the substitutions in the miscoded peptides take place at the C-terminal drop-off site. We further examined this observation using a reporter construct and found that the non-cognate pep-tRNAs produced by mistranslation rarely participate in the next round of elongation but dissociate from the ribosome, suggesting that pep-tRNA drop-off is an active mechanism by which the ribosome rejects miscoded pep-tRNAs in the early elongation, thereby contributing to quality control of protein synthesis after peptide bond formation.
Project description:Accurate translation of mRNAs into functional proteins is a fundamental process in all living organisms. In bacteria, in the early stage of translation elongation, peptidyl-tRNAs (pep-tRNAs) with short nascent chains frequently dissociate from the ribosome (pep-tRNA drop-off). The dissociated pep-tRNAs are deacylated and recycled by peptidyl-tRNA hydrolase (PTH), which is an essential enzyme in bacteria. Here, we establish a highly sensitive method for direct profiling of pep-tRNAs using RNA isolation method and mass spectrometry. We isolated each tRNA species with peptide from Escherichia coli pthts cells using reciprocal circulating chromatography and precisely analyzed their nascent peptides. As a result, we successfully detected 703 peptides consisted of 402 cognate peptides and 301 non-cognate peptides with single amino-acid substitution. Detailed analysis of individual pep-tRNAs revealed that most of the substitutions in the miscoded peptides take place at the C-terminal drop-off site. We further examined this observation using a reporter construct and found that the non-cognate pep-tRNAs produced by mistranslation rarely participate in the next round of elongation but dissociate from the ribosome, suggesting that pep-tRNA drop-off is an active mechanism by which the ribosome rejects miscoded pep-tRNAs in the early elongation, thereby contributing to quality control of protein synthesis after peptide bond formation.
Project description:Accurate translation of mRNAs into functional proteins is a fundamental process in all living organisms. In bacteria, in the early stage of translation elongation, peptidyl-tRNAs (pep-tRNAs) with short nascent chains frequently dissociate from the ribosome (pep-tRNA drop-off). The dissociated pep-tRNAs are deacylated and recycled by peptidyl-tRNA hydrolase (PTH), which is an essential enzyme in bacteria. Here, we establish a highly sensitive method for direct profiling of pep-tRNAs using RNA isolation method and mass spectrometry. We isolated each tRNA species with peptide from Escherichia coli pthts cells using reciprocal circulating chromatography and precisely analyzed their nascent peptides. As a result, we successfully detected 703 peptides consisted of 402 cognate peptides and 301 non-cognate peptides with single amino-acid substitution. Detailed analysis of individual pep-tRNAs revealed that most of the substitutions in the miscoded peptides take place at the C-terminal drop-off site. We further examined this observation using a reporter construct and found that the non-cognate pep-tRNAs produced by mistranslation rarely participate in the next round of elongation but dissociate from the ribosome, suggesting that pep-tRNA drop-off is an active mechanism by which the ribosome rejects miscoded pep-tRNAs in the early elongation, thereby contributing to quality control of protein synthesis after peptide bond formation.
Project description:Accurate translation of mRNAs into functional proteins is a fundamental process in all living organisms. In bacteria, in the early stage of translation elongation, peptidyl-tRNAs (pep-tRNAs) with short nascent chains frequently dissociate from the ribosome (pep-tRNA drop-off). The dissociated pep-tRNAs are deacylated and recycled by peptidyl-tRNA hydrolase (PTH), which is an essential enzyme in bacteria. Here, we establish a highly sensitive method for direct profiling of pep-tRNAs using RNA isolation method and mass spectrometry. We isolated each tRNA species with peptide from Escherichia coli pthts cells using reciprocal circulating chromatography and precisely analyzed their nascent peptides. As a result, we successfully detected 703 peptides consisted of 402 cognate peptides and 301 non-cognate peptides with single amino-acid substitution. Detailed analysis of individual pep-tRNAs revealed that most of the substitutions in the miscoded peptides take place at the C-terminal drop-off site. We further examined this observation using a reporter construct and found that the non-cognate pep-tRNAs produced by mistranslation rarely participate in the next round of elongation but dissociate from the ribosome, suggesting that pep-tRNA drop-off is an active mechanism by which the ribosome rejects miscoded pep-tRNAs in the early elongation, thereby contributing to quality control of protein synthesis after peptide bond formation.
Project description:This project applied a dry non-invasive method to detect palaeoproteomic evidence from stained manuscripts. The manuscript analysed in this study is a medieval parchment birth girdle (Wellcome Collection Western MS. 632) made in England and thought to be used by pregnant women while giving birth. Using a dry non-invasive sampling method we were able to extract both human and non-human peptides from the stains, including evidence for the use of honey, cereals, ovicaprine milk and legumes. In addition, a large number of human peptides were detected on the birth roll, many of which are found in cervico-vaginal fluid. This suggests that the birth roll was actively used during childbirth. This study is the first to extract and analyse non-collagenous peptides from a parchment document using a dry non-invasive sampling method and demonstrates the potential of this type of analysis for stained manuscripts, providing direct biomolecular evidence for active use.