Transient expression pattern of prolactin in Sparus aurata

Abstract

Using reverse transcription-polymerase chain reaction and in situ hybridization, the expression of the prolactin (PRL) gene was determined during development in gilthead sea bream (Sparus aurata) for the first time. The mRNA for PRL was detected from the second day of the larval stage onwards. This transcript was also located in the adenohypophysial cells, starting at four days post-hatching and was found to be pituitary-specific. Moreover, the possible involvement of PRL in asynchronous growth in the cultivation of gilthead sea bream was also examined. No differences in the distribution of PRL cells were observed in the three sizes of juvenile gilthead sea bream studied. These results suggest that the transcription of PRL is involved in the early development stages of sea bream and that the asynchronous growth-related changes are not due to distinct distribution of PRL cells.

Melatonin concentrations during larval and postlarval development of gilthead sea bream Sparus auratus: more than a time‐keeping molecule?

“…At this time, in S. auratus levels of hormones involved in growth, metabolism and development, i.e . growth hormone (GH) and prolactin (PRL), are very low (Herrero‐Turrión et al ., 2003 a,b ). It has been demonstrated that the number of GH cells and GH mRNA expression does not increase until 30 dph (Herrero‐Turrión et al ., 2003 b ).…”

Growth hormone expression in ontogenic development in gilthead sea bream

“…In contrast, in the current study, GH transcripts have been detected by RT-PCR and localized using ISH, at 2 and 4 days respectively. Thus, as we also observed in the ontogenic study of PRL transcript in this species (Herrero-Turrión et al 2003a), there is a small discrepancy in the cellular localization of the GH protein and its respective transcript. This is probably due to the fact that, as already mentioned, the GH gene is transcript translated in some embryonic period, and in newly hatched larvae, the GH protein accumulates in the cytoplasm in free form or in secretion vesicles and the corresponding mRNA becomes degraded.…”

“…The distinct expression levels possibly fluctuated due to differential regulation of gene expression according to the larval stage. The differences in these levels of expression of saGH in larvae have also been observed in this species for PRL (Herrero-Turrión et al 2003a) and SL (Funkenstein et al 1997;Herrero-Turrión et al 2003b). Thus, the establishment of a negative feedback by insulin growth factor 1 (IGF-I), which mediates the action of GH and PRL Moriyama et al 2000), could vary the levels of these transcripts (Reinecke and Collet 1998).…”

“…Nevertheless, a distinct differential secretion of GH could be suggested by the differences among the hypophysial sizes/volumes and the number of adenohypophysial cells. Therefore, no asynchronic growth-related changes were observed in the distribution of GH cells, nor in the distribution of lactotropes (Herrero-Turrión et al 2003a) and SL cells (Herrero-Turrión et al 2002). Therefore, although GH is essential for growth and development throughout the development of fish, in gilthead sea bream the asynchronous growth cannot be due to different distributions of lactotroph cells.…”

“…Hybridization procedures were as described elsewhere (Herrero-Turrión et al 2002, 2003a. Before carrying out the hybridization, the sections were postfixed with PFA and acetylated in a solution with 1.5% triethanolamine, 150 mM NaCl and 0.25% acetic anhydride to avoid false-positive results.…”