References of "Prunet, P"
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See detailTransfer of Tilapia (Oreochromis niloticus) to a hyperosmotic environment is associated with sustained expression of prolactin receptor in intestine, gill and kidney
Sandra, O.; Le Rouzic, P.; Rentier-Delrue, Françoise ULg et al

in General and Comparative Endocrinology (2001)

Expression of tilapia prolactin receptor (tiPRL-R) has been characterised in the intestine, gill and kidney of tilapia species Oreochromis niloticus and the levels of both tiPRL-R transcripts and tiPRL ... [more ▼]

Expression of tilapia prolactin receptor (tiPRL-R) has been characterised in the intestine, gill and kidney of tilapia species Oreochromis niloticus and the levels of both tiPRL-R transcripts and tiPRL binding sites have been analysed in these organs during adaptation tilapia to a hyperosmotic environment. [less ▲]

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See detailRecombinant prolactin Receptor Extracellular Domain of Rainbouw trout (Oncorhynchus mykiss): subcloning, preparation and characterization
Sandowski, Y.; Cohen, Y.; Le Rouzic, P. et al

in General and Comparative Endocrinology (2000), 118

The cDNA of the extracellular domain of rainbow trout (Oncorhynchus mykiss) prolactin receptor (trPRLR-ECD) was cloned in the prokaryotic expression vector pMON to enable its expression in Escherichia ... [more ▼]

The cDNA of the extracellular domain of rainbow trout (Oncorhynchus mykiss) prolactin receptor (trPRLR-ECD) was cloned in the prokaryotic expression vector pMON to enable its expression in Escherichia coli after induction with nalidixic acid. The bacterially expressed trPRLR-ECD protein, contained within the refractile body pellet, was solubilized in 4.5 M urea, refolded, and purified on a Q-Sepharose column, pH 8, by stepwise elution with NaCl. The bioactive monomeric 26-kDa fraction was eluted in 0.2 M NaCl, yielding 20 mg/2.5 L of induced culture. The purified protein was over 98% homogeneous, as shown by SDS-PAGE in the presence or absence of reducing agent and by chromatography on a Superdex column. Binding experiments using [125I]ovine placental lactogen (oPL) as a ligand revealed that human growth hormone (hGH), oPL, and ovine prolactin (oPRL) were the most effective competitors, with respective IC50 values of 1.32, 2.27, and 2.70 nM. Chicken (ch) PRL did not compete at all, and homologous trPRL was much less effective, with a corresponding IC50 value of 1826 nM. Gel-filtration was used to determine the stoichiometry of trPRLR-ECD's interaction with oPL, hGH, and oPRL. Only oPL yielded a 2:1 complex, whereas hGH and oPRL formed only 1:1 complexes, with excess trPRLR-ECD being seen at the initial 2:1 trPRLR-ECD:hGH or trPRLR-ECD:oPRL ratios. No studies were performed with chPRL because of its inability to compete with [125I]oPL or with trPRL because of its low affinity toward trPRLR-ECD. The present results agree with previous findings indicating, as in mammals, that homologous PRL interacts transiently with its receptor and suggest that transient homologous PRL-induced homodimerization of the receptor is sufficient to initiate a biological signal, despite the fact that, in classical binding experiments, only low specific binding can be detected. [less ▲]

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See detailAbsence of tiGh effect on adaptability to brackish water in Tilapia (Oreochromis niloticus)
Auperin, B.; Leguen, I.; Rentier-Delrue, Françoise ULg et al

in General and Comparative Endocrinology (1995)

The aim of this study was to investigate the possible role of growth hormone in the adaptation of tilapia (Oreochromis niloticus) to brackish water and to analyze its interactions with prolactin in this ... [more ▼]

The aim of this study was to investigate the possible role of growth hormone in the adaptation of tilapia (Oreochromis niloticus) to brackish water and to analyze its interactions with prolactin in this process. Plasma levels of growth hormone do not change upon transfer to brackish water. Treatment of intact tilapia in fresh water with growth hormone prior to transfer did not enable the fish to preadapt to brackish water: the duration of the hydromineral imbalance after transfer was the same in treated animals and controls. The major osmoregulatory role of prolactin in fresh water led us to test the hypothesis that prolactin might antagonize the effect of growth hormone on adaptation to brackish water. Growth-hormone-treated hypophysectomized animals, however, exhibited no increased osmoregulatory capacity as compared to hypophysectomized controls, confirming the absence of a growth-hormone-related osmoregulatory effect. When prolactin and growth hormone were coinjected, growth hormone also proved unable to oppose the Na+ retaining effect of prolactin, in both brackish and fresh water. Surprisingly, hypophysectomized animals adapt better to brackish water than do sham-operated animals. This result is discussed in light of the effects of prolactin and cortisol on osmoregulation in brackish water and we suggest that an important event which allows O. niloticus to adapt to hyperosmotic environment is the reduction of plasma PRL upon transfer to brackish water. [less ▲]

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See detailRegulation of gill prolactin receptors in tilapia (Oreochromis niloticus) after a change in salinity or hypophysectomy
Auperin, B.; Rentier-Delrue, Françoise ULg; Martial, Joseph ULg et al

in Journal of Endocrinology (1995), 145(2), 213-20

Prolactin (PRL) receptors in gill tissue have been analyzed in tilapia (Oreochromis niloticus) after transfer from fresh water (FW) to brackish water (BW). This study has indicated the presence of only ... [more ▼]

Prolactin (PRL) receptors in gill tissue have been analyzed in tilapia (Oreochromis niloticus) after transfer from fresh water (FW) to brackish water (BW). This study has indicated the presence of only one class of tilapia PRL (tiPRL) receptor whatever the salinity. After transfer, however, the percentage of specific binding of the two forms of tiPRL (tiPRLI and tiPRLII) increased significantly. Scatchard analysis of tiPRLI binding indicated an increase in receptor affinity, an effect which was not accompanied by any change in receptor specificity. Transfer to BW also caused the number of tiPRL receptors to increase rapidly, remaining high in fish adapted to BW for 28 days. Based on the sharp reduction in plasma tiPRLI and tiPRLII levels after transfer to BW, one possible explanation may be that tiPRL itself is an important factor regulating the number of free receptors. This hypothesis finds support in the fact that the number of tiPRL receptors also increased in hypophysectomized fish reared in FW. However, the absence of change in receptor affinity after hypophysectomy suggested that yet other factors are involved in tiPRL receptor regulation during the transfer from FW to BW. The paradoxically high numbers of tiPRL receptors in the gills of BW-adapted tilapia, even though PRL is known to be a FW-adapting hormone, is discussed with regard to the environment in which tilapia live. [less ▲]

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See detailEvidence that two tilapia (Oreochromis niloticus) prolactins have different osmoregulatory functions during adaptation to a hyperosmotic environment
Auperin, B.; Rentier-Delrue, Françoise ULg; Martial, Joseph ULg et al

in Journal of Molecular Endocrinology (1994), 12(1), 13-24

Two forms of prolactin (tiPRLI and tiPRLII), with only 69% sequence identity, have been previously described in the cichlid fish tilapia (Oreochromis species). In the present study we have attempted to ... [more ▼]

Two forms of prolactin (tiPRLI and tiPRLII), with only 69% sequence identity, have been previously described in the cichlid fish tilapia (Oreochromis species). In the present study we have attempted to investigate the biological activity of these two prolactin forms during adaptation to a hyperosmotic environment. For this purpose, we have developed two highly sensitive (sensitivity: 0.05 ng/ml) and specific (cross-reactivity < 0.04%) radioimmunoassays for tiPRLI and tiPRLII, using recombinant hormones. When fish were directly transferred from fresh to brackish water, the measured levels of plasma tiPRLI and tiPRLII dropped abruptly until 12 h after transfer. Thereafter, plasma tiPRLII remained stable (around 0.5 ng/ml) until the end of the experiment, whereas plasma tiPRLI continued to decrease to undetectable levels. These different patterns of change are reflected in the calculated ratio of plasma tiPRLII to tiPRLI, which increased from 2-3 in fresh water-adapted fish to over 10 in fish which had spent 3 days or more in brackish water. The pituitary contents of tiPRLI and tiPRLII varied in a qualitatively similar fashion after transfer to brackish water. The tiPRLI content dropped continuously after 12 h, reaching one-twelfth of its initial level after 2 weeks. The pituitary tiPRLII content, on the other hand, did not decrease significantly until day 7, and after a 2-week exposure to brackish water it had only decreased by 50%. When injected into tilapia adapted to brackish water, both ovine prolactin and recombinant tiPRLI induced a clear dose-dependent ion-retaining effect. In contrast, the effect induced by tiPRLII treatment was markedly smaller and not dose-dependent. Northern blot analysis of tiPRL mRNAs using either a tiPRLI or a tiPRLII cDNA probe indicated the presence of two mRNAs differing in size: a 1.7 kb mRNA coding for tiPRLI and a 1.3 kb mRNA coding for tiPRLII. After transfer to brackish water, levels of the two mRNAs decreased similarly. The present study indicates that, in O. niloticus, the two forms of prolactin have different osmoregulatory roles during adaptation to brackish water. Accordingly, their synthesis are differentially regulated after transfer to a hyperosmotic environment, presumably at a post-transcriptional level. [less ▲]

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See detailCharacterization of a single prolactin (PRL) receptor in tilapia (Oreochromis niloticus) which binds both PRLI and PRLII
Auperin, B.; Rentier-Delrue, Françoise ULg; Martial, Joseph ULg et al

in Journal of Molecular Endocrinology (1994), 13(3), 241-51

In tilapia, there are two forms of prolactin (PRL) whose effects on sodium and chloride movements differ and depend on the living environment of the fish. To see whether different receptors or the same ... [more ▼]

In tilapia, there are two forms of prolactin (PRL) whose effects on sodium and chloride movements differ and depend on the living environment of the fish. To see whether different receptors or the same receptor mediates these different effects, we have characterized the specific binding of both forms of tilapia (ti)PRL in two osmoregulatory organs, the gill and kidney. Two recombinant tiPRLs were used for this analysis. The recombinant hormones had the same properties as the native hormones in a tilapia gill radioreceptor assay. Specific binding to gill and kidney membranes was increased by optimizing the quality of the tissue preparations (physiological state of fish, membrane preparation) and the incubation conditions (pH, salt concentrations, temperature, time). Under these optimized conditions, we detected only one class of high affinity PRL receptor in gill and kidney. Its binding affinity was higher for tiPRLI than for tiPRLII in both gill and kidney (for tiPRLI the respective affinity values were 2.9 and 2.3 x 10(10) per M, for tiPRLII they were 1.9 and 0.5 x 10(10) per M). In competition studies, tiPRLI was more potent, followed by tiPRLII and ovine (o)PRL. tiGH and oGH did not significantly displace either tiPRL. The receptor we have characterized thus recognizes quite specifically both tiPRLs. [less ▲]

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See detailEffect of prolactin on alpha and beta chloride cells in the gill epithelium of the saltwater adapted tilapia " Oreochromis niloticus"
Pisam, B.; Auperin, B.; Prunet, P. et al

in Anatomical Record (1993), 235

Tilapia (Oreochromis niloticus), 21 g average body weight, were divided into two groups. A group was maintained in fresh water, whereas another group was adapted for 2 weeks to 20% salt water. Among the ... [more ▼]

Tilapia (Oreochromis niloticus), 21 g average body weight, were divided into two groups. A group was maintained in fresh water, whereas another group was adapted for 2 weeks to 20% salt water. Among the latter, fishes were injected every 2 days for a week with tilapia prolactin (ti-PRL I). Gills were prepared for electron microscopy in order to determine the types and surface areas of chloride cells in each experimental condition. Two types of chloride cells, the alpha and beta cells were easily distinguished on the basis of their location and ultrastructural features in the gills of freshwater fishes, while only one type of cell, the saltwater alpha cells presumably derived from the transformation of the freshwater alpha cells, were encountered in saltwater adapted animals. After PRL injection of saltwater adapted fishes, small chloride cells, which displayed ultrastructural features similar to those of beta cells in freshwater tilapia, reappeared in interlamellar regions of the gills. In the same experimental conditions, the voluminous saltwater alpha cells showed a tendency to resume ultrastructural features more characteristic of the freshwater alpha cells from which they were derived. These observations tend to indicate that prolactin behaves as a "freshwater adapting hormone" and that beta cells are specifically involved in fish adaptation to freshwater living conditions. [less ▲]

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See detailProduction and purification of biologically active recombinant tilapia (Oreochromis niloticus) prolactins
Swennen, D.; Rentier-Delrue, Françoise ULg; Auperin, B. et al

in Journal of Endocrinology (1991), 131(2), 219-27

Recombinant expression vectors carrying tilapia prolactin-I or -II (tiPRL-I or tiPRL-II) cDNA were constructed and the tiPRL-I and II proteins were produced in E. coli as inclusion bodies. These inclusion ... [more ▼]

Recombinant expression vectors carrying tilapia prolactin-I or -II (tiPRL-I or tiPRL-II) cDNA were constructed and the tiPRL-I and II proteins were produced in E. coli as inclusion bodies. These inclusion bodies were dissolved in 6 mol urea/l. Refolding of the proteins was followed by SDS-PAGE under non-reducing conditions so as to visualize the oxidized state of the molecules. Proteins tiPRL-I and tiPRL-II were purified by gel filtration and ion-exchange chromatography. The N-terminal sequence and bioactivities of both purified proteins were then analysed. Recombinant tiPRL-I and tiPRL-II induced a significant rise in plasma calcium levels as well as in mucocyte density in the abdominal skin epithelium. When tested on kidney membrane, both proteins exhibited potency in competing with 125I-labelled tiPRL-I for binding sites, but tiPRL-I seemed to be more potent than tiPRL-II in competing for these sites. The results obtained for the biological activities tested suggest that both recombinant prolactins were correctly refolded and had retained the full biological activity previously observed with the natural hormone preparations extracted from the animals. [less ▲]

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See detailTilapia prolactin: molecular cloning of two cDNAs and expression in Escherichia coli
Rentier-Delrue, Françoise ULg; Swennen, D.; Prunet, P. et al

in DNA (1989), 8(4), 261-70

We have isolated cDNA clones encoding tilapia prolactin (tiPRL) from a cDNA library prepared from tilapia (Oreochromis niloticus) anterior pituitary glands. A trout PRL cDNA fragment was used as ... [more ▼]

We have isolated cDNA clones encoding tilapia prolactin (tiPRL) from a cDNA library prepared from tilapia (Oreochromis niloticus) anterior pituitary glands. A trout PRL cDNA fragment was used as hybridization probe to select the recombinant plasmids carrying the tiPRL coding sequence. Two types of PRL cDNA were isolated and their complete nucleotide sequence determined. The larger cDNA (tiPRL-I) codes for a polypeptide of 212 amino acids, including a putative signal sequence of 24 amino acids, and contains a 3' untranslated region of 787 bp. The second prolactin cDNA (tiPRL-II) encodes a polypeptide of 200 amino acids, including a presumptive signal peptide of 23 amino acids, and contains a noncoding region of 512 bp. tiPRL-I and tiPRL-II cDNA sequences are 81% similar, whereas the encoded proteins share 69% amino acid identity at optimal alignment. Mature tiPRL-I was efficiently expressed in Escherichia coli carrying a plasmid in which the tiPRL-I cDNA was under the control of the phi 10 promoter of T7 bacteriophage. The new recombinant protein representing about 45% of the total cellular proteins was found in inclusion bodies and cross-reacted with salmon PRL antiserum. [less ▲]

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See detailRainbow trout prolactin cDNA cloning in Escherichia coli
Mercier, L.; Rentier-Delrue, Françoise ULg; Swennen, D. et al

in DNA (1989), 8(2), 119-25

We describe the isolation and characterization of a cDNA for trout prolactin (tPrl). An extensive analysis of tPrl recombinant clones by restriction analysis and sequencing revealed the presence of only ... [more ▼]

We describe the isolation and characterization of a cDNA for trout prolactin (tPrl). An extensive analysis of tPrl recombinant clones by restriction analysis and sequencing revealed the presence of only one form of tPrl mRNA. The deduced protein sequence consists of 210 amino acids, including a signal peptide of 23 amino acids. The amino acid sequence of the mature protein is compared among teleosts and mammals, showing two domains of strong similarity that may be involved in biological activity. [less ▲]

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