Induction of ovarian growth in Aegla platensis (Crustacea, Aeglidae) by means of neuroregulators incorporated to food

The freshwater crab Aegla platensis was used as a model to induce ovarian growth by adding different neuroregulators to a pellet food formulation. Added compounds were the dopaminergic inhibitor spiperone or the enkephalinergic inhibitor naloxone, both of them at a dose of 10-8 mol/animal. Animals were fed on the enriched pellets twice a week. After 7 wk, the gonadosomatic index (GI) was calculated as (gonad fresh weight / body fresh weight) x 100. GI significantly increased only for those females fed on spiperone pellets, compared to a control group receiving pellets with no compound added. During the assayed period, spiperone would be reverting the arrest exerted by dopamine on the neuroendocrine stimulation of ovarian growth. On the other hand, for both spiperone and naloxone a higher GI was correlated to a higher lipid content of both gonads and/or hepatopancreas, suggesting an increased energetic demand in accordance with an active investment in reproduction. Rev. Biol. Trop. 56 (3): 1201-1207. Epub 2008 September 30.

Se utilizó al anomuro de agua dulce Aegla platensis como modelo para inducir el crecimiento ovárico mediante el agregado de diferentes neuroreguladores a una formulación de alimento pelleteado. Los compuestos agregados fueron el inhibidor dopaminergico spiperona ó el inhibidor encefalinérgico naloxone, ambos a una dosis de 10-8 moles/animal. Los animales fueron alimentados dos veces a la semana con pellets enriquecidos con alguno de los neuroreguladores. Luego de 7 semanas, se calculó el índice gonadomático (IG) como (peso gonadal fresco/ peso corporal fresco) x 100. El IG mostró un incremento significativamente sólo en aquellas hembras alimentadas con pellets enriquecidos con spiperona, en comparación con un grupo control que recibió pellets sin agregado alguno. Durante el período ensayado, la spiperona estaría revirtiendo el arresto ejercido por la dopamina sobre la estimulación neuroendocrina del crecimiento ovárico. Por otro lado, para ambos grupos experimentales (spiperona y naloxone), un mayor valor de IG estuvo correlacionado a un mayor incremento del contenido de lípidos tanto en gonadas como en hepatopáncreas, sugiriendo una demanda energética incrementada en relación con una activa inversión en reproducción.

Seasonal variations in the intermediate metabolism of Parastacus varicosus (Crustacea, Decapoda, Parastacidae).

The aim of this study was to analyze the seasonal variations in the metabolism of Parastacus varicosus and examine the possible relationships to its reproduction. Animals were sampled (9 h to 10 h) in each month in the Gravataí River, RS, Brazil. Haemolymph samples were collected from each crayfish in the field for determination of glucose, total proteins, total lipids, and total cholesterol. Hepatopancreas, abdominal muscle, and gonads were removed for determination of glycogen, total proteins, total lipids, and total cholesterol. ANOVA revealed significant seasonal differences in the biochemical composition of all tissues studied; when the sexes were compared these parameters did not show any significant difference in the hepatopancreas and muscle. However, in haemolymph we observed significant variation only in cholesterol and lipid levels. The results suggest that the metabolic variability is related to the stage of maturation of the gonads, in females, where the hepatopancreas and other tissue studies can store and transfer reserves to support maturation to complement the food intake. Variations in the gonadosomatic and hepatosomatic indices suggest that reproduction occurs principally in summer. As in other decapods, abiotic factors such as water temperature, oxygen content, etc. influence the intermediate metabolism.

Molecular systematics and biogeography of the southern South american freshwater "crabs" Aegla (decapoda: Anomura: Aeglidae) using multiple heuristic tree search approaches.

Recently new heuristic genetic algorithms such as Treefinder and MetaGA have been developed to search for optimal trees in a maximum likelihood (ML) framework. In this study we combined these methods with other standard heuristic approaches such as ML and maximum parsimony hill-climbing searches and Bayesian inference coupled with Markov chain Monte Carlo techniques under homogeneous and mixed models of evolution to conduct an extensive phylogenetic analysis of the most abundant and widely distributed southern South American freshwater"crab,"the Aegla(Anomura: Aeglidae). A total of 167 samples representing 64 Aegla species and subspecies were sequenced for one nuclear (28S rDNA) and four mitochondrial (12S and 16S rDNA, COI, and COII) genes (5352 bp total). Additionally, six other anomuran species from the genera Munida,Pachycheles, and Uroptychus(Galatheoidea), Lithodes(Paguroidea), and Lomis(Lomisoidea) and the nuclear 18S rDNA gene (1964 bp) were included in preliminary analyses for rooting the Aegla tree. Nonsignificantly different phylogenetic hypotheses resulted from all the different heuristic methods used here, although the best scored topologies found under the ML hill-climbing, Bayesian, and MetaGA approaches showed considerably better likelihood scores (Delta> 54) than those found under the MP and Treefinder approaches. Our trees provided strong support for most of the recognized Aegla species except for A. cholchol,A. jarai,A. parana,A. marginata, A. platensis, and A. franciscana, which may actually represent multiple species. Geographically, the Aegla group was divided into a basal western clade (21 species and subspecies) composed of two subclades with overlapping distributions, and a more recent central-eastern clade (43 species) composed of three subclades with fairly well-recognized distributions. This result supports the Pacific-Origin Hypothesis postulated for the group; alternative hypotheses of Atlantic or multiple origins were significantly rejected by our analyses. Finally, we combined our phylogenetic results with previous hypotheses of South American paleodrainages since the Jurassic to propose a biogeographical framework of the Aegla radiation.