Browsing by Author "Canario, Adelino V. M."
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- 11-ketotestosterone stimulates putative sex pheromone production in the male peacock blenny, Salaria pavo (Risso 1810)Publication . Serrano, Rui M.; Lopes, Orlando; Hubbard, Peter; Araújo, J.; Canario, Adelino V. M.; Barata, E. N.Male peacock blennies (Salaria pavo) release odors from their anal glands and, possibly, from their gonads that attract reproductive females. The current study investigated the effects of 11-ketotestosterone (KT) on development of the anal glands, testes, and accessory testicular organs as well as the subsequent olfactory potency of their secretions. After 3 wk of KT treatment (5 mg/kg in silastic implants), clusters of cells secreting neutral mucins differentiated in the anal gland of all treated males, whereas this occurred in only one control male. Secretions by anal glands from KT-treated males elicited greater olfactory responses, as assessed by electro-olfactography, than those from controls. Treatment with KT stimulated testicular gland growth and sialomucin secretion but had no clear effect on the germinal region of the testis; KT also stimulated enlargement of, and fluid secretion in, the blind pouches (paired evaginations of the spermatic ducts). Secretions by the testes and fluid in blind pouches from KT-treated males elicited greater olfactory responses than those from controls. In conclusion, KT stimulates development of the anal glands and testicular accessory organs and promotes odorant secretion, the putative multicomponent male peacock blenny pheromone.
- 16.P15. Branchial osmoregulatory response to salinity challenge in the Lusitanian toadfishPublication . Guerreiro, Pedro M; Laiz-Carrión, R.; Haond, Christophe; Modesto, Teresa; Fuentes, Juan; Mancera, J. M.; Canario, Adelino V. M.Halobatrachus didactylus, a marine teleost found in coastal lagoons and river estuaries is often exposed to important salinity changes. Despite its aglomerular kidney, it is able to survive in hypo-osmotic environments, likely via compensatory actions from gills and intestine. We aimed at evaluating the response of the branchial tissue of H. didactylus to salinity changes.
- 17a,20ß,21-trihydroxy-4-pregnen-3-one: the probable maturation-inducing steroid of the lusitanian toadfishPublication . Modesto, Teresa; Canario, Adelino V. M.17,20 ,21-Trihydroxy-4-pregnen-3-one (17,20 ,21-P) was identified as the major metabolite of incubations of Lusitanian toadfish Halobatrachus didactylus ovarian follicles with [3H]-17hydroxyprogesterone. The potency of several steroids in inducing germinal vesicle breakdown of follicle-enclosed oocytes of Lusitanian toadfish was systematically examined by using an in vitro germinal vesicle breakdown (GVBD) bioassay. 17,20 -Dihydroxy-4-pregnen-3-one (17,20 -P) and 17,20 ,21-P, two confirmed maturation-inducing steroids (MIS) in teleosts, were the most potent in inducing GVBD with ED50s ranging between 9 and 271 nM. Structure-activity relationships followed similar patterns to what has been observed in similar bioassays, i.e. a vital requirement for 17- and 20 -hydroxyl groups in C21 steroids and a reduction in activity of 14 and 5–6%, respectively, for 5-pregnene and 5 -pregnanes compared to 4-pregnenes. Corticosteroids, testosterone and 17 -oestradiol were ineffective. Folliculated oocytes stimulated by pituitary homogenate produced 17,20 ,21-P from endogenous substrates in amounts one order of magnitude higher than 17,20 -P. These results strongly support the hypothesis that 17,20 ,21-P is the likely MIS in this species.
- 2.P3. Cloning and gene expression of two novel stanniocalcin genes in the puffer fish Tetraodon nigroviridisPublication . Schein, V; Schein, Vanessa; Pinto, Patricia IS; Canario, Adelino V. M.Stanniocalcin 1 (STC1) is a hypocalcemic hormone first described in fishes. Recently a second gene (STC2) was isolated from mammals and fishes. However, in silico analysis of Tetraodon nigroviridis and Takifugu rubripes genomes revealed the presence of a third and a fourth gene. In this study STC1 was cloned from de Corpuscles of Stannius (CS), STC2 from the muscle, and the two novel genes identified, STC1B and STC2B from the brain of Tetraodon. The STC-1B gene encodes an ORF of 287aa and contains 11 conserved cyteine residues and the Nlinked glycosylation site, present in all identified STC1.
- Adaptation to different salinities exposes functional specialization in the intestine of the sea bream (Sparus aurata L.)Publication . Gregorio, Silvia; Carvalho, Edison Samir Mascarelhas; Encarnação, Sandra; Wilson, J.; Power, Deborah; Canario, Adelino V. M.; Fuentes, J.The processing of intestinal fluid, in addition to a high drinking rate, is essential for osmoregulation in marine fish. This study analyzed the long-term response of the sea bream (Sparus aurata L.) to relevant changes of external salinity (12, 35 and 55p.p.t.), focusing on the anterior intestine and in the less-often studied rectum. Intestinal water absorption, epithelial HCO3– secretion and gene expression of the main molecular mechanisms (SLC26a6, SLC26a3, SLC4a4, atp6v1b, CFTR, NKCC1 and NKCC2) involved in Cl– and HCO3– movements were examined. The anion transporters SLC26a6 and SLC26a3 are expressed severalfold higher in the anterior intestine, while the expression of Atp6v1b (V-type H+-ATPase β-subunit) is severalfold higher in the rectum. Prolonged exposure to altered external salinity was without effect on water absorption but was associated with concomitant changes in intestinal fluid content, epithelial HCO3– secretion and salinity-dependent expression of SLC26a6, SLC26a3 and SLC4a4 in the anterior intestine. However, the most striking response to external salinity was obtained in the rectum, where a 4- to 5-fold increase in water absorption was paralleled by a 2- to 3-fold increase in HCO3– secretion in response to a salinity of 55p.p.t. In addition, the rectum of high salinity-acclimated fish shows a sustained (and enhanced) secretory current (Isc), identified in vitro in Ussing chambers and confirmed by the higher expression of CFTR and NKCC1 and by immunohistochemical protein localization. Taken together, the present results suggest a functional anterior–posterior specialization with regard to intestinal fluid processing and subsequently to salinity adaptation of the sea bream. The rectum becomes more active at higher salinities and functions as the final controller of intestinal function in osmoregulation.
- Adaptation to reduced salinity affects the olfactory sensitivity of Senegalese sole (Solea senegalensis Kaup 1858) to Ca2+ and Na+ but not amino acidsPublication . Velez, Zélia; Hubbard, Peter; Barata, E. N.; Canario, Adelino V. M.The Senegalese sole is a marine flatfish, which often penetrates into estuarine waters to feed. It cannot, however, survive in full freshwater. The current study investigated the effect of adaptation to low salinity (10‰) on olfactory responses to changes in environmental [Ca2+] and [Na+] and amino acids by the electro-encephalogram (EEG) recorded from the olfactory bulb. The sole showed olfactory responses to increases in environmental [Na+] and decreases in environmental [Ca2+]; sensitivity to Na+ was greater at 10‰ whereas sensitivity to Ca2+ was greater at 35‰. Decreased environmental [Na+] increased sensitivity to changes in [Ca2+] whereas increased environmental [Ca2+] decreased bulbar responses to changes in [Na+]. Sensitivity to amino acids was unaffected by external salinity. However, the absence of external Na+ strongly decreased bulbar responses to amino acids in fish adapted to 35‰ seawater but not in those at 10‰. The absence of external Ca2+ had no such effect at either salinity. This suggests that odorant-receptor binding and/or olfactory transduction is reliant on external Na+ (but not Ca2+) at higher salinities but the olfactory system is able to adapt to lower environmental [Na+]. Taken together, these results suggest that reductions of external salinity modulate olfactory sensitivity to environmental Ca2+ and Na+ but not amino acids. However, at low salinities, olfactory sensitivity to amino acids is maintained by decreasing reliance on external Na+.
- Advances in european sea bass genomics and future perspectivesPublication . Louro, Bruno; Power, Deborah; Canario, Adelino V. M.Only recently available sequenced and annotated teleost fish genomes were restricted to a few model species, none of which were for aquaculture. Application of Marker Assisted Selection for improved production traits had been largely restricted to the salmon industry and genetic and Quantitative Trait Loci (QTL) maps were available for only a few species. With the advent of Next Generatio Sequencing the landscape is rapidly changing and today the genomes of several aquaculture species have been sequenced. The European sea bass, Dicentrarchus labrax, is a good example of a 17 commercially important aquaculture species in Europe for which in the last decade a wealth of genomic resources, including a chromosomal scale genome assembly, physical and linkage maps as well as relevant QTL have been generated. The current challenge is to stimulate the uptake of the resources by the industry so that the full potential of this scientific endeavour can be exploited and produce benefits for producers and the public alike.
- Alternative transcripts of DMRT1 in the European sea bass: expression during gonadal differentiationPublication . Deloffre, Laurence A. M.; Martins, Rute S. T.; Mylonas, Constantinos C.; Canario, Adelino V. M.DMRT1 is conserved from invertebrates to human and has been implicated in sex differentiation and testis function in many organisms.We report the cloning of two DMRT1 transcripts, DMRT1a and DMRT1b, encoded by a single gene in the European sea bass, Dicentrarchus labrax, a teleost fish with polygenic sex determination influenced by temperature. DMRT1a and DMRT1b are specific to the testis and are present as transcripts of 2.7 and 4.6 kb, as determined by Northern blot, although the cloned cDNAs are 1.2 and 1.9 kb. DMRT1a, encodes a protein of 306-amino acids, of similar size to what has been found in other teleosts, while the DMRT1b encodes a unique protein which differ from DMRT1a by having a 26 amino acids insertion which separates the S and Y domains. This insertion is the result of an extra exon (exon 4), present in the genomes of teleosts but not in other vertebrate genomes. Furthermore, unlike in the European sea bass, the putative product of DMRT1b in other teleost species is a truncated peptide. In European sea bass, the two transcripts are expressed at a similar level and have a similar expression profile in developing gonads. They are first detected by reverse transcription-polymerase chain reaction at 150 days post-hatch coinciding with the start of sex differentiation. After 200 days, expression increases in testis and decreases in ovary. Although it is not clear whether the two transcripts have differential roles it is suggested that both are required for testicular function.
- Analysis of the goldfish Carassius auratus olfactory epithelium transcriptome reveals the presence of numerous non-olfactory GPCR and putative receptors for progestin pheromonesPublication . Kolmakov, Nikolai N.; Kube, M.; Reinhardt, Richard; Canario, Adelino V. M.The goldfish (Carassius auratus) uses steroids and prostaglandins as pheromone cues at different stages of the reproductive cycle to facilitate spawning synchronization. Steroid progestin pheromone binding has been detected in goldfish olfactory membranes but the receptors responsible for this specific binding remain unknown. In order to shed some light on the olfactory epithelium transcriptome and search for possible receptor candidates a large set of EST from this tissue were analysed and compared to and combined with a similar zebrafish (Danio rerio) resource.
- Analysis of the Sox gene family in the european sea bass (Dicentrarchus labrax)Publication . Galay-Burgos, M.; Llewellyn, Lynda; Mylonas, Constantinos C.; Canario, Adelino V. M.; Zanuy, Silvia; Sweeney, Glen E.Sox (SRY-related genes containing a HMG box) genes encode a family of transcription factors that are involved in a variety of developmental processes including sex determination. Twenty Sox genes are present in the genomes of humans and mice, but far less is known about the Sox gene family in other vertebrate types. We have obtained clones representing the HMG boxes of twelve Sox genes from European sea bass (Dicentrarchus labrax), a fish species whose farming is complicated by a heavily skewed sex ratio, with between 70% and 99% of offspring typically being male. The cloned Sox genes are members of the SoxB, SoxC, SoxE and SoxF groups. Sequence analysis shows that some of the clones represent genes duplicated in sea bass with respect to the mammalian Sox gene family.