16 research outputs found
Diversity, mobility, and structural and functional evolution of group II introns carrying an unusual 3' extension
<p>Abstract</p> <p>Background</p> <p>Group II introns are widespread genetic elements endowed with a dual functionality. They are catalytic RNAs (ribozymes) that are able of self-splicing and they are also mobile retroelements that can invade genomic DNA. The group II intron RNA secondary structure is typically made up of six domains. However, a number of unusual group II introns carrying a unique extension of 53-56 nucleotides at the 3' end have been identified previously in bacteria of the <it>Bacillus cereus </it>group.</p> <p>Methods</p> <p>In the present study, we conducted combined sequence comparisons and phylogenetic analyses of introns, host gene, plasmid and chromosome of host strains in order to gain insights into mobility, dispersal, and evolution of the unusual introns and their extension. We also performed in vitro mutational and kinetic experiments to investigate possible functional features related to the extension.</p> <p>Results</p> <p>We report the identification of novel copies of group II introns carrying a 3' extension including the first two copies in bacteria not belonging to the <it>B. cereus </it>group, <it>Bacillus pseudofirmus </it>OF4 and <it>Bacillus sp</it>. 2_A_57_CT2, an uncharacterized species phylogenetically close to <it>B. firmus</it>. Interestingly, the <it>B. pseudofirmus </it>intron has a longer extension of 70 bases. From sequence comparisons and phylogenetic analyses, several possible separate events of mobility involving the atypical introns could be identified, including both retrohoming and retrotransposition events. In addition, identical extensions were found in introns that otherwise exhibit little sequence conservation in the rest of their structures, with the exception of the conserved and catalytically critical domains V and VI, suggesting either separate acquisition of the extra segment by different group II introns or a strong selection pressure acting on the extension. Furthermore, we show by in vitro splicing experiments that the 3' extension affects the splicing properties differently in introns belonging to separate evolutionary branches.</p> <p>Conclusions</p> <p>Altogether this study provides additional insights into the structural and functional evolution of unusual introns harboring a 3' extension and lends further evidence that these introns are mobile with their extension.</p
Sex Knowledge and Attitude Among Medical Interns in a Tertiary Care Hospital Attached to Medical College in Ahmedabad, Gujarat
The administration of polymerized human hemoglobin (pyridoxylated) to a jehovah's witness after submyeloablative stem cell transplantation complicated by delayed graft failure
Escalating-dose HLA-mismatched DLI is safe for the treatment of leukaemia relapse following alemtuzumab-based myeloablative allo-SCT
The strengthening starts at home: Parentâchild relationships, psychological capital, and academic performance â a longitudinal mediation analysis
DNA methyltransferase inhibition increases efficacy of adoptive cellular immunotherapy of murine breast cancer
High-Functioning Autistic Students Speak About Their Experience of Inclusion in Mainstream Secondary Schools
Soil organic phosphorous speciation using spectroscopic techniques
Soil Biology; Vol. 26The most commonly used differentiation of soil phosphorus (P) is between inorganic and organic forms, despite the fact that this is only the beginning of soil P speciation. Forms of inorganic and organic soil P include a large range of specific P compounds, and spectroscopic techniques can offer the best potential for determining the speciation of soil organic P. The focus of this chapter is to summarise the relative merits of three spectroscopic techniques: solution and solid state 31P nuclear magnetic resonance (NMR), and X-ray absorption near-edge structure (XANES). We aim to provide current and potential end-users of these techniques the ability to compare these methods on the basis of four criteria: sample preparation, sensitivity, resolution and quantitation.Ashlea L. Doolette and Ronald J. Smerni