Browsing by Author "Garcia-Lopez, A."
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- Non-invasive assessment of reproductive status and cycle of sex steroid levels in a captive wild broodstock of Senegalese sole Solea senegalensis (Kaup)Publication . Garcia-Lopez, A.; Anguis, V.; Couto, Elsa; Canario, Adelino V. M.; Canavate, J. P.; Sarasquete, C.; Martínez-Rodriguez, G.Senegalese sole, Solea senegalensis, intensive culture is currently limited mainly due to the low control on reproduction in captivity. Comprehensive knowledge of reproductive biology and physiology for this species is needed in order to improve tank spawning success. This work describes for the first time the seasonal profiles of plasma levels of sex steroids (17β-estradiol, testosterone, 11- ketotestosterone, and 17,20β-dihydroxy-4-pregnen-3-one [17,20β-P]) in a S. senegalensis captive wild broodstock held under natural conditions, during two consecutive reproductive cycles. Changes in apparent maturation in females, dynamics of sperm release in males, and the condition factor (K) were monitored. Sixmaturation stages were established for females according to apparent size of the ovary and external abdominal swelling: early, intermediate and final ovarian development (F2+, F3+ and F4+, respectively), and partially spawned, mid spawned and spawned out or regressed (F3−, F2−, and F1−, respectively). During summer, F1− and nonrunning males (NRM) were predominant in association with low K and plasma steroid levels. At the end of summer, a new cycle of gonadal development started, denoted by the increase in reproductive parameters (K and steroid levels) and the appearance of F2+. By middle autumn, some females reached advancedmaturation stages (F3+ and F4+)while the proportion of runningmales (RM) showed a maximum. An occasional spawning could be registered during this season (November 2002). Towards the end of winter and beginning of spring, ovarian development reached its maximum. At this point, the proportion of F3+, F4+ and RM, K (specially in females), and steroid concentrations were the highest in concordance with the starting of the main spawning period (lasting from January to June 2003 and fromMarch to June 2004). Throughout this period, concomitantly with oocyte and sperm release, the proportion of F3−, F2−, F1− and NRMprogressively increased, while steroid levels and K progressively declined (concentration of steroids could fluctuate under a decreasing trend). The relatively elevated levels of 17,20β-P correlating with some parts of the spawning periods makes it a candidate for the role of the maturation-inducing steroid in S. senegalensis. Seasonal variations of measured parameters were consistent with the reproductive cycle of this species in the wild, and comparable to those found in other asynchronous multi-spawning fish.
- Ovarian development and plasma sex steroid levels in cultured female Senegalese sole Solea senegalensisPublication . Garcia-Lopez, A.; Couto, Elsa; Canario, Adelino V. M.; Sarasquete, C.; Martínez-Rodriguez, G.Ovarian development was studied in cultured female Senegalese sole Solea senegalensis. Females with regressed ovaries, mainly occupied by perinucleolar oocytes, predominated throughout summer exhibiting low condition factor (K), gonadosomatic index (IG), and plasma 17β-estradiol and testosterone levels. Throughout autumn and winter (ovaries at early and intermediate maturation), oocytes progressed to cortical alveoli and vitellogenic stages accompanied by increasing K, IG, and plasma 17β-estradiol and testosterone levels. At late winter/early spring, ovarian development reached its maximum with the predominance of females at intermediate and final maturation (the latter occupied by late vitellogenic oocytes and few early maturation oocytes) and peak values of K, IG, and 17β-estradiol and testosterone concentrations. Steroid levels were lower (especially testosterone) than those for naturally-spawning females, which might cause extensive atresia without final oocyte maturation (no spawning was observed). This degenerative process reduced de size of the ovary (initial and intermediate phases of regression) in association with declining K, IG, and plasma 17β-estradiol and testosterone levels and increasing proportions of perinucleolar oocytes. The circulating 17,20β-dihydroxy-4-pregnen-3-one levels, the proposed maturation-inducing steroid, remained relatively constant throughout the experimental period, suggesting that oocytes were unable to respond adequately to its stimulation. We propose the inadequate seasonal thermal regime as the main cause of such dysfunction.
- Testicular development and plasma sex steroid levels in cultured male Senegalese sole Solea senegalensis KaupPublication . Garcia-Lopez, A.; Fernandez-Pasquier, V.; Couto, Elsa; Canario, Adelino V. M.; Sarasquete, C.; Martínez-Rodriguez, G.Testicular development and plasma levels of sex steroids (11-ketotestosterone (11-KT), testosterone (T) and 17,20 -dihydroxy-4-pregnen-3-one (17,20 -P)) were investigated for the Wrst time in cultured male Senegalese sole Solea senegalensis. The germ cell dynamics and gonadosomatic index (IG) were monitored. Based on the relative abundance of the diVerent types of germ cells present, the spermatogenetic cycle was divided into Wve stages: early (I; spermatogonia (SPG)), mid (II; SPG, spermatocytes (SPC) and spermatids (SPD)), and late spermatogenesis (III; SPC, SPD, and spermatozoa (SPZ)), functional maturation (IV; SPD and SPZ), and recovery (V; SPD, SPZ, and SPG). During summer, Wsh had stage I and V testes and the lowest values in plasma levels of sex steroids and IG. Testicular recrudescence seemed to begin in autumn, as denoted by the Wrst increase in IG and in the levels of 11-KT and T, and the appearance of testes at stage II and III. During winter, the levels of 11-KT and T peaked and soon began to decrease, the IG slightly declined and the proportion of running males (RM) gradually increased. In spring, levels of 11-KT and T continued to decline, the IG slightly increased and the proportion of RM peaked concomitantly with the occurrence of stage IV testes. Plasma levels of 17,20 -P did not change signiWcantly throughout testicular development. Transformation of SPD into SPZ followed a group-synchronous fashion, a phenomenon which parallels asynchronous oocyte development reported in females. This mechanism would be consistent with the observed small quantity of sperm that can be manually stripped at any one time and other aspects of S. senegalensis reproductive biology.