1,721,021 research outputs found
ESPRESSIONE GENICA DIFFERENZIALE IN EMBRIONI MASCHIO E EMBRIONI FEMMINA DI GECO LEOPARDO (Eublepharis macularius)
No full textIntron retention: a human DKC1 gene common splicing event.
No full textIdentification of alternatively spliced transcripts produced by a gene is a crucial step in deciphering the bulk of its
biological roles and the overall processes that regulate its activity. By using a combination of bioinformatic and molecular
approaches we identified, cloned, and characterized 3 novel alternative splice isoforms derived from human dyskeratosis
congenita 1 (hDKC1), an essential human gene causative of the X-linked dyskeratosis congenita disease and involved in multiple
functions related to cell growth, proliferation, and telomere maintenance. Expression of the new isoforms, all characterized by
intron retention, was confirmed by RT-PCR in a panel of diverse cell lines and normal human tissues, and despite the presence
of premature termination codons, was not down-regulated by the mechanism of nonsense-mediated decay. Accumulation of
these transcripts fluctuated distinctly in the diverse tissues and during in vitro differentiation of Caco2 cells, suggesting that
their ratio may contribute to the gene functional diversity across different cell types. Intriguingly, the structure of one isoform
leads to exonize an intronically encoded small nucleolar RNA (snoRNA), highlighting an additional layer of complexity that can
contribute to overall gene regulation
Human dyskerin: beyond telomeres
No full textHuman dyskerin is an evolutively conserved protein
that participates in diverse nuclear complexes: the
H/ACA snoRNPs, that control ribosome biogenesis, RNA
pseudouridylation, and stability of H/ACA snoRNAs; the
scaRNPs, that control pseudouridylation of snRNAs; and the
telomerase active holoenzyme, which safeguards telomere
integrity. The biological importance of dyskerin is further
outlined by the fact that its deficiency causes the X-linked
dyskeratosis congenita disease, while its over-expression
characterizes several types of cancers and has been proposed
as prognostic marker. The role of dyskerin in telomere
maintenance has widely been discussed, while its functions
as H/ACA sno/scaRNP component has been so far mostly
overlooked and represent the main goal of this review. Here
we summarize how increasing evidence indicates that the
snoRNA/microRNA pathways can be interlaced, and that
dyskerin-dependent RNA pseudouridylation represents a
flexible mechanism able to modulate RNA function in different
ways, including modulation of splicing, change of
mRNA coding properties, and selective regulation of IRESdependent translation. We also propose a speculative model that suggests that the dynamics of pre-assembly and nuclear import of H/ACA RNPs are crucial regulatory steps that can be finely controlled in the cytoplasm in response to developmental, differentiative and stress stimuli
Preferential Use of the Perchlorate over the Nitrate in the Respiratory Processes Mediated by the Bacterium Azospira sp. OGA24
No full textHere we report the results obtained for a strain isolated from a polluted site and classified as Azospira sp. OGA 24. The capability of OGA24 to utilize perchlorate and nitrate and the regulation of pathways were investigated by growth kinetic studies and analysis of messenger RNA (mRNA) expression of the genes of perchlorate reductase alpha subunit (pcrA), chlorite dismutase (cld), and periplasmic nitrate reductase large subunit (napA). In aerobic conditions and in a minimal medium containing 10 mM acetate as carbon source, 5.6 ± 0.34 mmol L−1 perchlorate or 9.7 ± 0.22 mmol L−1 nitrate were efficiently reduced during the growth with 10 mM of either perchlorate or nitrate. In anaerobiosis, napA was completely inhibited in the presence of perchlorate as the only electron acceptor, pcrA was barely detectable in nitrate-reducing conditions. The cell growth kinetics were in accordance with expression data, indicating a separation of nitrate and perchlorate respiration pathways. In the presence of both compounds, anaerobic nitrate consumption was reduced to 50% (4.9 ± 0.4 vs. 9.8 ± 0.15 mmol L−1 without perchlorate), while that of perchlorate was not affected (7.2 ± 0.5 vs. 6.9 ± 0.6 mmol L−1 without nitrate). Expression analysis confirmed the negative effect of perchlorate on nitrate respiration. Based on sequence analysis of the considered genes and 16S ribosomal gene (rDNA), the taxonomic position of Azospira sp. OGA24 in the perchlorate respiring bacteria (PRB) group was further defined by classifying it in the oryzae species. The respiratory characteristics of OGA24 strain make it very attractive in terms of potential applications in the bioremediation of environments exposed to perchlorate salt
The coding/non-coding overlapping architecture of the gene encoding the Drosophila pseudouridine synthase.
Full text linkBackground: In eukaryotic cells, each molecule of H/ACA small nucleolar RNA (snoRNA)
assembles with four evolutionarily conserved core proteins to compose a specific
ribonucleoprotein particle. One of the four core components has pseudouridine synthase activity
and catalyzes the conversion of a selected uridine to pseudouridine. Members of the pseudouridine
synthase family are highly conserved. In addition to catalyzing pseudouridylation of target RNAs,
they carry out a variety of essential functions related to ribosome biogenesis and, in mammals, to
telomere maintenance. To investigate further the molecular mechanisms underlying the expression
of pseudouridine synthase genes, we analyzed the transcriptional activity of the Drosophila
member of this family in great detail.
Results: The Drosophila gene for pseudouridine synthase, minifly/Nop60b (mfl), encodes two novel
mRNAs ending at a downstream poly(A) site. One species is characterized only by an extended 3'-
untranslated region (3'UTR), while a minor mRNA encodes a variant protein that represents the
first example of an alternative subform described for any member of the family to date. The rare
spliced variant is detected mainly in females and is predicted to have distinct functional properties.
We also report that a cluster comprising four isoforms of a C/D box snoRNA and two highly
related copies of a small ncRNA gene of unknown function is intron-encoded at the gene-variable
3'UTRs. Because this arrangement, the alternative 3' ends allow mfl not only to produce two
distinct protein subforms, but also to release different ncRNAs. Intriguingly, accumulation of all
these intron-encoded RNAs was found to be sex-biased and quantitatively modulated throughout
development and, within the ovaries, the ncRNAs of unknown function were found not
ubiquitously expressed.
Conclusion: Our results expand the repertoire of coding/non-coding transcripts derived from the
gene encoding Drosophila pseudouridine synthase. This gene exhibits a complex and interlaced
organization, and its genetic information may be expressed as different protein subforms and/or
ncRNAs that may potentially contribute to its biological functions
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