ECDYSONES IN THE MATURATIONAL MOULT OF JUVENILE FEMALES OF THE SPIDER CRAB, LIBINIA EMARGINATA LEACH, 1815 (DECAPODA, MAJIDAE)
Authors: Takac Peter , Rottlant Guiomar 
Published: March 2012

In this study we examined the role of ecdysteroids in the differentiational moult and in sexual maturation of juvenile female Libinia emarginata, using eyestalk ablation and radioimmunoassay. In eyestalk intact control animals, the ecdysteroids increased significantly in the hemolymph, from 11.26 ng/ml at the beginning of the experiment to 89.68 ng/ml by 68 days (7 days before moulting). In eyestalk ablated animals the ecdysteroids rose to 148.30 ng/ml by 20 days under our rearing conditions and moulting occurred 30 days after the beginning of the experiment. Ecdysteroids accumulated in the fresh ovaries prior to moulting, increasing from 30.38 ng/g at day 1 to 296.01 ng/g in control animals by day 73 (2 days prior to moulting). In ablated females they increased in a similar manner reaching 321.2 ng/g 10 days prior to moulting. All ablated juvenile females moulted into juveniles, while all controls moulted into adults. Our results suggest that in addition to regulating moulting, ecdysteroids may play a role in the morphological changes involved with maturation since eyestalk ablated animals remained juvenile. spider crabs has been related to degeneration of the Y-organs in species such as Maja squinado (Herbst, 1788) (cf. Carlisle, 1957) and Acanthonyx lunulatus (Risso, 1816) (cf. Chaix et al., 1976). Female spider crabs undergo a differentiational moult from the juvenile form to the adult, after which they become anecdysic. The morphology affected by the differentiational moult is the shape of the abdomen. In immature females the abdomen is narrow and does not completely cover the sternites; in adults it is broadly oval and completely covers the ventral surface between the walking legs. The maximum carapace length (CL) of immature females found in wild populations is 60 mm (15). Mature females exceed 40 mm CL, so, in the 40- 60 mm range, females may be mature or immature. En este estudio se examino el rol de los ecdisteroides en la muda de diferenciacion y la maduracion sexual de las hembras juveniles de Libinia emarginata utilizando ablacion peduncular y radioinmunoensayo. En animales peduncularmente intactos o controles los ecdisteroides incrementaron significativamente en la hemolinfa, de 11.26 ng/ml al principio del experimento a 89.68 ng/ml a los 68 doas (7 d oas antes de mudar). En animales epedunculados los ecdisteroides alcanzaron 148.30 ng/ml tras 20 doas de cultivo y mudaron a los 30 d oas desde el inicio del experimento. Los ecdisteroides acumulados en los ovarios de animales controles antes de mudar, incrementaron de 30.38 ng/g el primer doa a 296.01 ng/g despu es de 73 doas de cultivo (2 d oas antes de mudar). En las hembras epedunculadas incrementaron de manera similar alcanzando 321.20 ng/g 10 doas antes de mudar. Todas las hembras juveniles epedunculadas mudaron en juveniles, mientras que todas las controles mudaron en adultos. Nuestros resultados sugieren que adem as de regular la muda, los ecdisteroides puden jugar un papel en los cambios morfologicos relacionados con la maduracion ya que los animales epedunculados permanecieron juveniles.