Post-transcriptional regulation of ornithine decarboxylase in Xenopus laevis oocytes

Development ◽  
1990 ◽  
Vol 110 (3) ◽  
pp. 955-962 ◽  
Author(s):  
T. Bassez ◽  
J. Paris ◽  
F. Omilli ◽  
C. Dorel ◽  
H.B. Osborne
Keyword(s):  
Xenopus Laevis ◽  
Ornithine Decarboxylase ◽  
Stage Iv ◽  
Stage I ◽  
Northern Analysis ◽  
Xenopus Laevis Oocytes ◽  
Temporal Expression ◽  
Post Transcriptional Regulation ◽  
Translational Level

The level at which ornithine decarboxylase expression is regulated in growing oocytes has been investigated. Immunoprecipitation of the in vivo labelled proteins showed that ornithine decarboxylase accumulated less rapidly in stage IV oocytes than in previtellogenic stage I + II oocytes. Quantitative Northern analysis showed that ornithine decarboxylase mRNA is abundant in oocytes (about 8 × 10(8) transcripts/cell) and this number does not significantly change during oogenesis. Polysome analysis showed that this mRNA is present in polysomes in stage I + II oocytes but has passed into puromycin-insensitive mRNP particles by stage IV of oogenesis. Therefore, during the growth phase of oogenesis, ornithine decarboxylase expression is regulated at a translational level. These results are discussed relative to the temporal expression of ornithine decarboxylase and of other proteins whose expression also decreases during oogenesis. In order to perform these experiments, the cDNA (XLODC1) corresponding to Xenopus laevis ornithine decarboxylase mRNA was cloned and sequenced.

scholarly journals Actions of Agonists, Fipronil and Ivermectin on the Predominant In Vivo Splice and Edit Variant (RDLbd, I/V) of the Drosophila GABA Receptor Expressed in Xenopus laevis Oocytes

PLoS ONE ◽  
2014 ◽  
Vol 9 (5) ◽  
pp. e97468 ◽  
Author(s):  
Kristin Lees ◽  
Maria Musgaard ◽  
Siros Suwanmanee ◽  
Steven David Buckingham ◽  
Philip Biggin ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Gaba Receptor ◽  
Xenopus Laevis Oocytes

Purification of a p47 phosphoprotein from Xenopus laevis oocytes and identification as an in vivo and in vitro p34cdc2 substrate

FEBS Letters ◽  
1989 ◽  
Vol 251 (1-2) ◽  
pp. 219-224 ◽  
Author(s):  
Odile Mulner-Lorillon ◽  
Robert Poulhe ◽  
Patrick Cormier ◽  
Jean-Claude Labbe ◽  
Marcel Doree ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Xenopus Laevis Oocytes

scholarly journals Using in vivo imaging to measure RNA mobility in Xenopus laevis oocytes

Methods ◽  
2016 ◽  
Vol 98 ◽  
pp. 60-65 ◽  
Author(s):  
Erin A. Powrie ◽  
Veronica Ciocanel ◽  
Jill A. Kreiling ◽  
James A. Gagnon ◽  
Bjӧrn Sandstede ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
In Vivo Imaging ◽  
Xenopus Laevis Oocytes

Physiological and molecular characterization of urea transport by the gills of the Lake Magadi tilapia (Alcolapia grahami)

2001 ◽  
Vol 204 (3) ◽  
pp. 509-520 ◽  
Author(s):  
P.J. Walsh ◽  
M. Grosell ◽  
G.G. Goss ◽  
H.L. Bergman ◽  
A.N. Bergman ◽  
...  
Keyword(s):  
Short Interval ◽  
Northern Analysis ◽  
Xenopus Laevis Oocytes ◽  
Urea Transport ◽  
Urea Transporter ◽  
Pavement Cells ◽  
Urea Excretion ◽  
Lake Magadi ◽  
Alcolapia Grahami

The Lake Magadi tilapia (Alcolapia grahami) is an unusual fish, excreting all its nitrogenous waste as urea because of its highly alkaline and buffered aquatic habitat. Here, using both physiological and molecular studies, we describe the mechanism of branchial urea excretion in this species. In vivo, repeated short-interval sampling revealed that urea excretion is continuous. The computed urea permeability of A. grahami gill is 4.74×10(−)(5)+/−0.38×10(−)(5)cm s(−)(1) (mean +/− s.e.m., N=11), some 10 times higher than passive permeability through a lipid bilayer and some five times higher than that of even the most urea-permeable teleosts studied to date (e.g. the gulf toadfish). Transport of urea was bidirectional, as demonstrated by experiments in which external [urea] was elevated. Furthermore, urea transport was inhibited by classic inhibitors of mammalian and piscine urea transporters in the order thiourea>N-methylurea>acetamide. A 1700 base pair cDNA for a putative Magadi tilapia urea transporter (mtUT) was cloned, sequenced and found to display high homology with urea transporters from mammals, amphibians and other fishes. When cRNA transcribed from mtUT cDNA was injected into Xenopus laevis oocytes, phloretin-inhibitable urea uptake was enhanced 3.4-fold relative to water-injected controls. Northern analysis of gill, red blood cells, liver, muscle and brain using a portion of mtUT as a probe revealed that gill is the only tissue in which mtUT RNA is expressed. Magadi tilapia gill pavement cells exhibited a trafficking of dense-cored vesicles between the well-developed Golgi cisternae and the apical membrane. The absence of this trafficking and the poor development of the Golgi system in a non-ureotelic relative (Oreochromis niloticus) suggest that vesicle trafficking could be related to urea excretion in Alcolapia grahami. Taken together, the above findings suggest that the gills of this alkaline-lake-adapted species excrete urea constitutively via the specific facilitated urea transporter mtUT.

Xenopus laevis oocytes, eggs and tadpoles contain immunoactive insulin

1994 ◽  
Vol 141 (1) ◽  
pp. 123-129 ◽  
Author(s):  
F de Pablo ◽  
R Dashner ◽  
A R Shuldiner ◽  
J Roth
Keyword(s):  
Xenopus Laevis ◽  
High Performance ◽  
Immunoblot Analysis ◽  
Reversed Phase ◽  
Xenopus Laevis Oocytes ◽  
Maternal Origin ◽  
Insulin Mrna ◽  
Low Levels

Abstract Insulin is a multifunctional polypeptide hormone that regulates metabolic processes and promotes mitogenesis and differentiation in vitro in the cells and tissues of several species. Its role in vivo during embryogenesis is still poorly understood. We have previously found insulin mRNA in mature Xenopus laevis oocytes and in embryos during neurulation (before organogenesis of the pancreas takes place). We have now measured insulin immunoactivity in mature oocytes, unfertilized eggs and day-2 tadpoles. Using reversed phase high performance liquid chromatography, we found low levels of insulin in extracts of oocytes (stage VI). Both Xenopus insulin I and II were detected in unfertilized eggs. The day-2 tadpoles (stages 31–33) also contained immunoactive insulin, and in swimming tadpoles (stage 46) a few clusters of cells containing insulin immunoactivity could be identified by indirect immunofluorescence. Immunoblot analysis was relatively insensitive, detecting insulin only in the adult Xenopus pancreas. In summary, insulin (from maternal origin and embryonic expression) appears to be present early enough in Xenopus laevis to influence developmental processes such as neurulation. Journal of Endocrinology (1994) 141, 123–129

Accurate in vitro transcription of Xenopus laevis mitochondrial DNA from two bidirectional promoters

1986 ◽  
Vol 6 (7) ◽  
pp. 2543-2550
Author(s):  
D F Bogenhagen ◽  
B K Yoza
Keyword(s):  
Mitochondrial Dna ◽  
Xenopus Laevis ◽  
Rna Polymerase ◽  
Consensus Sequence ◽  
In Vitro Transcription ◽  
Xenopus Laevis Oocytes ◽  
Mitochondrial Rna ◽  
Bidirectional Promoters

The mitochondrial RNA polymerase from Xenopus laevis oocytes was partially purified by heparin-Sepharose chromatography and phosphocellulose chromatography. This RNA polymerase preparation specifically initiated the transcription of X. laevis mitochondrial DNA (mtDNA) from two bidirectional promoters contained within a 123-base-pair segment of the mtDNA between the heavy-strand replication origin and the rRNA cistrons. Transcription in vitro initiated from precisely the same start sites previously mapped as initiation sites for transcription in vivo. At each of the four sites, initiation occurred within a conserved nucleotide sequence, ACPuTTATA. This consensus sequence is not related to promoters for transcription of human mtDNA.

High tyrosinase activity in albino Xenopus laevis oocytes

Development ◽  
1976 ◽  
Vol 36 (3) ◽  
pp. 555-559
Author(s):  
A. H. Wyllie ◽  
E. M. De Robertis
Keyword(s):  
Molecular Weight ◽  
Xenopus Laevis ◽  
Specific Activity ◽  
High Specific Activity ◽  
Low Molecular Weight ◽  
Xenopus Laevis Oocytes ◽  
Melanin Synthesis ◽  
Wild Type ◽  
Albino Mutant

Tyrosinase was measured in oocytes of the recently described albino mutant (avav) of Xenopus laevis. Although these oocytes show no pigmentation and the eggs are known to contain no melanosomes, tyrosinase — which is probably the only enzyme necessary for melanin synthesis from tyrosine — was increased more than twofold relative to the wild type. Tyrosinase recovered from albino and wild type oocytes showed the same KM with respect to tyrosine, and this was not altered by previous gonadotrophin stimulation in vivo. The tyrosi-nase assay, based on [14]tyrosine incorporation into acid-insoluble products, was of greater sensitivity than previously described methods of the same type, through removal of low molecular weight material from the oocyte homogenate prior to incubation, and the use of tyrosine of high specific activity.

Lens regeneration from cornea of larval Xenopus laevis in the presence of the lens

Development ◽  
1978 ◽  
Vol 48 (1) ◽  
pp. 205-214
Author(s):  
Julie G. Reeve ◽  
Arthur E. Wild
Keyword(s):  
Xenopus Laevis ◽  
Histological Examination ◽  
Cell Layer ◽  
Stage Iv ◽  
Stage Iii ◽  
Posterior Chamber ◽  
Lens Regeneration ◽  
Lens Fibre

In Xenopus laevis tadpoles, wounding of the outer cornea failed to initiate lens regeneration. If both the outer and inner corneas were wounded or if the lens was dislocated, lens regeneration was initiated but failed to continue beyond stage III. However, lensectomy followed by re-implantation of the lens resulted in the regeneration of a fully differentiated lens in several cases, despite the presence of the re-implanted lens. Although some of the regenerates in these eyes were also arrested at stage III, those which attained full lens differentiation, i.e. stage V, developed normally and synthesized crystallins from the onsetof stage IV as indicated by a positive immunofluorescence reaction. Histological examination of the dislocated and re-implanted lenses showed the majority of them to be normal in appearance. Cornea transplanted to the posterior chamber of the eye also regenerated a lens in the presence of the re-implanted lens. All these regenerates underwent lens fibre differentiation to give stage-V regenerates. These findings show that lens regeneration from the cornea can occur in the presence of lens. Results are discussed on the basis that contrary to earlier suggestions, an inhibitory lens factor does not exist in vivo, but rather that a factor for the initiation and maintenance of regeneration emanates from the eye cup and upon wounding of the inner cornea is able to reach the inner cell layer of the outer cornea and initiate lens regeneration.

Protooncogene product, c-mos kinase, is involved in upregulating Na+/H+ antiporter in Xenopus oocytes

1994 ◽  
Vol 267 (6) ◽  
pp. C1717-C1722 ◽  
Author(s):  
K. Rezai ◽  
A. Kulisz ◽  
W. J. Wasserman
Keyword(s):  
Plasma Membrane ◽  
Xenopus Laevis ◽  
Intracellular Ph ◽  
Xenopus Oocytes ◽  
Stage Iv ◽  
Meiotic Maturation ◽  
Xenopus Laevis Oocytes ◽  
Cell Systems ◽  
Oocyte Meiotic Maturation

Progesterone-stimulated Xenopus laevis oocytes undergo an increase in their intracellular pH from 7.3 to 7.7 because of the activation of Na+/H+ antiporters in their plasma membrane. Activation of Na+/H+ exchangers (NHE) in other cell systems appears to be regulated by phosphorylation of the NHE protein. In the current study we demonstrated that cytoplasm taken from steroid-stimulated oocytes rapidly induced an increase in intracellular pH when microinjected into full-grown stage VI recipient oocytes. The protein within the cytoplasm that appears to be responsible for this activity is c-mos kinase. Microinjected pure mosxe kinase protein rapidly activated the Na+/H+ exchangers in full-grown recipient oocytes. Furthermore, injected mosxe protein rapidly activated the Na+/H+ exchangers in smaller progesterone-insensitive stage IV oocytes. Therefore, it appears that the protooncogene product, p39 c-mos kinase, which is normally synthesized in full-grown stage VI oocytes in response to progesterone stimulation, is involved in the upregulation of the Na+/H+ antiporters during oocyte meiotic maturation.

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