319 research outputs found
The pseudouridine contents of the ribosomal ribonucleic acids of three vertebrate species. Numerical correspondence between pseudouridine residues and 2′-O-methyl groups is not always conserved
Comparison between the ribosomal ribonucleic acids from free and membrane-bound ribosomal fractions of HeLa cells
Methylated nucleotide sequences in HeLa-cell ribosomal ribonucleic acid. Correlation between the results from ‘fingerprinting’ hydrolysates obtained by digestion with T1 ribonuclease and with T1 plus pancreatic ribonuclease
Extensive homologies between the methylated nucleotide sequences in several vertebrate ribosomal ribonucleic acids
Evidence on the conformation of HeLa-cell 5.8S ribosomal ribonucleic acid from the reaction of specific cytidine residues with sodium bisulphite
Biosynthesis of a hypermodified nucleotide in Saccharomyces carlsbergensis 17S and HeLa-cell 18S ribosomal ribonucleic acid
Clones of human ribosomal DNA containing the complete 18 S-rRNA and 28 S-rRNA genes. Characterization, a detailed map of the human ribosomal transcription unit and diversity among clones
Retinoic Acid Signalling and the Control of Meiotic Entry in the Human Fetal Gonad
The development of mammalian fetal germ cells along oogenic or spermatogenic fate trajectories is dictated by signals from the surrounding gonadal environment. Germ cells in the fetal testis enter mitotic arrest, whilst those in the fetal ovary undergo sex-specific entry into meiosis, the initiation of which is thought to be mediated by selective exposure of fetal ovarian germ cells to mesonephros-derived retinoic acid (RA). Aspects of this model are hard to reconcile with the spatiotemporal pattern of germ cell differentiation in the human fetal ovary, however. We have therefore examined the expression of components of the RA synthesis, metabolism and signalling pathways, and their downstream effectors and inhibitors in germ cells around the time of the initiation of meiosis in the human fetal gonad. Expression of the three RA-synthesising enzymes, ALDH1A1, 2 and 3 in the fetal ovary and testis was equal to or greater than that in the mesonephros at 8–9 weeks gestation, indicating an intrinsic capacity within the gonad to synthesise RA. Using immunohistochemistry to detect RA receptors RARα, β and RXRα, we find germ cells to be the predominant target of RA signalling in the fetal human ovary, but also reveal widespread receptor nuclear localization indicative of signalling in the testis, suggesting that human fetal testicular germ cells are not efficiently shielded from RA by the action of the RA-metabolising enzyme CYP26B1. Consistent with this, expression of CYP26B1 was greater in the human fetal ovary than testis, although the sexually-dimorphic expression patterns of the germ cell-intrinsic regulators of meiotic initiation, STRA8 and NANOS2, appear conserved. Finally, we demonstrate that RA induces a two-fold increase in STRA8 expression in cultures of human fetal testis, but is not sufficient to cause widespread meiosis-associated gene expression. Together, these data indicate that while local production of RA within the fetal ovary may be important in regulating the onset of meiosis in the human fetal ovary, mechanisms other than CYP26B1-mediated metabolism of RA may exist to inhibit the entry of germ cells into meiosis in the human fetal testis
What’s retinoic acid got to do with it? Retinoic acid regulation of the neural crest in craniofacial and ocular development
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151310/1/dvg23308.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151310/2/dvg23308_am.pd
The varied roles of nuclear receptors during vertebrate embryonic development
Nuclear receptors comprise a superfamily of sequence-specific transcription factors whose members have diverse roles during development. This review will summarize the developmental roles of selected members of the nuclear receptor superfamily
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