1,055 research outputs found
Ordered processing of the polygenic transcripts from a mitochondrial transfer-RNA gene cluster in K. lactis.
No full textIn Saccharomyces cerevisiae, transcription of the mitochondrial genome starts at multiple initiation sites and is followed by the processing of multigenic transcripts at the 5' and 3' termini of tRNA sequences and in some intergenic regions. We have used a comparative approach to investigate the structure and function of the latter processing sites. We present here an analysis of the transcripts of a cluster of tRNA genes from the mitochondrial genome of Kluyveromyces lactis. The gene order of this cluster is the same as that of the cluster in S. cerevisiae but the sequence of the intergenic regions is different. A detailed analysis of transcripts has been performed using S1 mapping and primer extension techniques. The results can be summarized as follows: (1) transcription of the cluster very probably starts at initiation sites having the nonanucleotide sequence TTATAAGTA (which acts as a promoter in S. cerevisiae) and yields polygenic transcripts; (2) processing of these transcripts seems to occur through an ordered pathway of endonucleolytic events in which some tRNA sequences are preferentially excised and some endonucleolytic cuts occur more readily than others; (3) in two intergenic regions, strong signals indicate the existence of processing events. The sequences around these sites are similar in sequence and localization to S. cerevisiae intergenic processing sites, indicating a possible functional importance in maintaining a conserved order of tRNA genes in different species of yeasts
Analysis of transcripts of the major cluster of tRNA genes in the mitochondrial genome of S. cerevisiae
No full textThe transcripts of a 6Kbp region of the mitochondrial genome of S. cerevisiae, localized in the 21S rRNA-OXI1 span and including 12 tRNA genes (from tRNA(thr) to tRNA(ala)) and several G+C clusters, have been studied by analysis of in vitro capped primary transcripts and by fine mapping of the 5' ends of transcripts. The study was performed in the w.t. strain D273-10B and in several rho- mutants retaining different, partially overlapping portions of the studied region; the mutants accumulate incompletely-processed precursors of tRNAs due to the absence of the tRNA synthesis locus. Results show the presence in the region of four sites at which initiation occurs at a consensus nonanucleotide ATTATAAGTA (or a minor variant of the same); however different initiation sites are used in different strains, and several differences as compared to initiation in vitro can also be observed. Termini arising by processing are often localized at AATATAA or AATATATTTT sequences localized immediately adjacent to a G+C cluster or a tRNA sequence
P720 Recurrent rectovaginal fistula in patients with Crohn’s disease: How can we improve the success rate of graciloplasty? A bi-centric European study in 30 patients
No full textNucleo-mitochondrial interactions in Saccharomyces cerevisiae: characterisation of a nuclear gene suppressing a defect in mitochondrial tRNAAsp processing.
No full textWe utilized the heat-sensitive mutant strain (Ts932), bearing a mutation at position 61 in the mitochondrial tRNAAsp gene, to identify
nuclear genes involved in tRNA biogenesis; this mutant is defective in 30-end processing and consequently in the production of mature
mitochondrial tRNAAsp. We transformed this strain with a yeast nuclear library and we isolated among other suppressors, an unknown, nonessential
gene (called SMM1, corresponding to open reading frame YNR015w), which restored the growth on glycerol and a normal amount
of processed tRNAAsp in the mutant. The gene contains a domain highly conserved in evolution from bacteria to human and its product has
been recently shown to have dihydrouridine synthase activity
Cancer in perianal fistulas
No full textThe presence of a perianal fistula as a complication related to Crohn's disease (CD) was first described by Penner and by Burrill Crohn himself in 1938 [1]. Since then, intense efforts have been made and significant economic resources spent in order to improve the quality of life of patients with inflammatory bowel diseases (IBDs) who also have perianal fistulas. Unfortunately, the results have been poor regardless of the medical or surgical treatment adopted. The incidence of perianal disease is 20-25% in CD patients with terminal ileitis, but it increases to as high as 60% in CD with a colonic location and 92% when the rectum is actively involved [2-4]. In ulcerative colitis (UC) perianal suppurative lesions are less common, but the incidence of perianal abscesses and fistulas is still reported to be between 10% and 15% [5]
Valutazione del risultato estetico di impianti a connessione morse-taper nei settori frontali
No full textLo studio presenta i dati estetici di impianti a connessione conometrica inseriti nei settori frontali dei mascellari con un protocollo di carico immediato non funzional
The ermes complex is essential for mitochondrial inheritance and lipid biogenesis in S.cerevisiae
No full textTranscription of the large tRNA gene cluster in the mitochondrial genome of S.cerevisiae.
No full text
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