Time filter

Source Type

Orlando L.,Direccion Nacional de Recursos Acuaticos DINARA | Pereyra I.,Direccion Nacional de Recursos Acuaticos DINARA | Paesch L.,Direccion Nacional de Recursos Acuaticos DINARA | Norbis W.,Direccion Nacional de Recursos Acuaticos DINARA | Norbis W.,Laboratorio Of Fisiologia Of La Reproduccion Y Ecologia Of Peces
Brazilian Journal of Oceanography | Year: 2011

In this work we analyzed the spatial and seasonal variation of length distribution, sexual proportion and mature dominance for Atlantoraja cyclophora and A. castelnaui, at the Uruguayan continental shelf. There were significant differences in total length (TL) composition between sexes, being females bigger than males for both species. Atlantoraja cyclophora showed a relatively uniform length distribution between inner and outer shelf. There were no major variations in the sex compositions and in the mature dominance between seasons, suggesting no temporal variation. Atlantoraja castelnaui showed a significant variation in its spatial and seasonal distribution. Individuals were smaller in inner shelf, pointing out the existence of juvenile zone in areas up to 50 m depth. A tendency to capture smaller individuals towards the end of the year was observed. In all seasons over 50% of females were caught below the estimated size at maturity, suggesting that this species is highly susceptible to exploitation. Source

Vizziano-Cantonnet D.,Laboratorio Of Fisiologia Of La Reproduccion Y Ecologia Of Peces | Anglade I.,French National Center for Scientific Research | Pellegrini E.,French National Center for Scientific Research | Gueguen M.-M.,French National Center for Scientific Research | And 3 more authors.
General and Comparative Endocrinology | Year: 2011

Using genetic monosex male and female rainbow trout populations, the potential sex differences in the central expression of estrogen receptors (esr1, esr2a, esr2b), brain aromatase (cyp19a1b) and some other steroidogenic enzymes was studied over the period of sex differentiation (from 35 to 63 dpf: days post-fertilization) using quantitative polymerase chain reaction (q-PCR). In addition, aromatase activity was evaluated during this period. The results indicated that brain aromatase (cyp19a1b) expression and activity showed a clear and significant sexually dimorphic pattern with higher levels in male brain between 35 and 53 dpf before the time of gonad morphological differentiation. At that time the expression of a key enzyme involved in the conversion of cholesterol into steroids, the cyp11a1 (p450scc), as well as the estrogen receptors were also sexually dimorphic. The dimorphism was lost from 56 dpf onwards. Transcription factors such as nr5a1b (s. f1) and nr0b1 (dax1), but not foxl2a were also higher in males than in females. These results demonstrate that, before or during the early period of morphological gonad differentiation, the brain exhibits a clear sexual dimorphism with respect to the expression and activity of aromatase as well as of certain enzymes and factors involved in steroid synthesis as p450scc and sf1. The results suggest a higher potentiality to produce estrogens by male brains during sex differentiation time. © 2010 Elsevier Inc. Source

Blasco M.,Buenos Aires Institute of Technology | Fernandino J.I.,Buenos Aires Institute of Technology | Guilgur L.G.,Buenos Aires Institute of Technology | Strussmann C.A.,Tokyo University of Marine Science and Technology | And 2 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2010

Sex steroids are known to be involved in gonadal differentiation in fish, but whether androgens are early mediators of testis differentiation remains unclear. We studied the sex-related developmental variations in the gene expression of two key enzymes involved in steroids and androgen synthesis (cyp11a1 and cyp11b1) in trunks and isolated gonads of pejerrey (Odontesthes bonariensis) larvae during and after the sex determination period. Also, and in order to have a better characterization of this process we studied the expression of Sertoli (dmrt1, amh, sox9) and Leydig (nr5a1 or sf-1) cell markers as well as a gene with higher expression in females (cyp19a1a). No clear differences were observed in the expression of cyp11a1 and cyp11b1 during the temperature-sensitive window in the trunk of pejerrey larvae. Nevertheless, a clear increase of cyp11b1 was observed in isolated gonads taken from fish reared at the male producing temperature. In these gonads we also confirmed the trends of genes with higher expression in males (dmrt1, amh) and females (cyp19a1a) as previously described in larval trunks of pejerrey. Our results showed that the expression of cyp11b1 was positively associated with the morphological differentiation of the testis. Nevertheless the involvement of 11-oxygenated androgens during the temperature-sensitive window could not be clearly established. © 2010 Elsevier Inc. All rights reserved. Source

Orlando L.,Laboratorio Of Fisiologia Of La Reproduccion Y Ecologia Of Peces | Pereyra I.,Area de Biodiversidad y Conservacion | Silveira S.,DINARA MGAP | Paesch L.,DINARA MGAP | And 2 more authors.
Neotropical Ichthyology | Year: 2015

This work analyzed length-mass relationship, growth in length, mass variations and dynamic of yolk sac depletion of Mustelus schmitti embryos, extracted from females catched by the artisanal fishery acting off La Paloma (34°39’S, 54°10´W, Uruguay) during 2006 and 2007. Differences in total length and total mass between sexes were not significant. Embryos showed a negative allometric growth for both years with a slope change near the day 170 of the year, likely to be associated with the depletion of the external yolk sac. Gompertz and Von Bertalanffy curves were adjusted for each year. Parturition date was determined around the day 300 of the year. Yolk depletion followed a logistic dynamic Yt=1/ (1+e(-13.749 + 0.072*t)) for 2006 and Yt=1/(1+e(-10.472 + 0.054*t)) for 2007. Embryos showed a mean increase in total dry mass of 5.4g in 187 days which, together with yolk depletion dynamics, indicates additional energetic supply, suggesting that M. schmitti presents limited histotrophy. © 2015 Sociedade Brasileira de Ictiologia. Source

Tellechea J.S.,Laboratorio Of Fisiologia Of La Reproduccion Y Ecologia Of Peces | Tellechea J.S.,University of Puerto Rico at San Juan | Bouvier D.,University of the Republic of Uruguay | Norbis W.,Laboratorio Of Fisiologia Of La Reproduccion Y Ecologia Of Peces
Bioacoustics | Year: 2011

Recordings with a hydrophone deployed from a boat and the shore revealed that the sciaenid Whitemouth Croaker Micropogonias furnieri produces a seasonal and daily characteristic courtship/spawning sound in the Pando stream mouth on the Rio de la Plata estuary during the spawning season from November to March. Recordings were made at five stations. The drumming sound was qualitatively rated on scale of 0-4, according to criteria proposed by Connaughton & Taylor (1995). Recordings of 5 marked individuals were made in a 3000-1 canvas tank in the laboratory for three months (December 2006 - March 2007). The drumming or advertisement call of Whitemouth Croaker was strongly seasonal, appearing in October, increasing to a peak in January - March, and then disappearing abruptly in April, in coincidence with the spawning season and with gonadosomatic index (GSI). Daily drumming activity showed two peaks through the day, increasing in the early morning between 07:00 to 10:00 h and in the evening between 17:00 to 23:00 h. © 2011 AB Academic Publishers. Source

Discover hidden collaborations