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- Localization and distribution of nitric oxide synthase and other neuronal markers in the podia ofHolothuria arguinensisPublication . Marquet, Nathalie; Canario, Adelino; Power, DeborahThe organization of the nervous system of the holothurian podia-the tentacles, papillae, and tube feet-is still poorly understood, which limits the development of functional studies. Knowledge of nitric oxide (NO) signaling in sea cucumbers is nonexistent, although it is known to play an important role in many essential biological functions, including neurotransmission, throughout the animal kingdom. The objective of this study was to characterize the holothurian podia inHolothuria arguinensis. To this end, we used classical histology, nitric oxide synthase (NOS) distribution, using NADPH-diaphorase histochemistry and NOS immunostaining, and neuronal immunohistochemistry. Our results revealed an abundant distribution of NO in the nervous components of the holothurian podia, suggesting an important role for NO as a neuronal messenger in these structures. Nitrergic fibers were intensely labeled in the longitudinal nerve and the nerve plexus surrounding the stem, but were more weakly labeled in the mesothelium. NOS was also found in scattered cell bodies and abundant fibers in the podia terminal end (i.e., the discs in tentacles and tube feet, and the pointed conical structures in the papillae), with evident neuronal projections to the bud surface, especially in the tentacles. The podia terminal end was the most specialized area and was characterized by a specific nervous arrangement, consisting of a distinct nerve plate, rich in cells and fibers containing potential sensory cells staining positively for neuronal markers, which makes this the most likely candidate to be a chemosensory region and an important candidate for future exploration.
- Sea cucumbers, Holothuria arguinensis and H-mammata, from the southern Iberian Peninsula: variation in reproductive activity between populations from different habitatsPublication . Marquet, Nathalie; Conand, Chantal; Power, Deborah; Canario, Adelino; Gonzalez-Wanguemert, MercedesNew fisheries in the western Mediterranean and north eastern Atlantic target the sea cucumbers Holothuria arguinensis and H. mammata; however, lack of biological information hinders management decisions. Here, the reproductive biology of populations the two species was investigated in the southern Iberian Peninsula. Different populations located along a narrow latitudinal range displayed the same general reproductive pattern of summer-autumn spawning. However, significant differences in size, gonadal production and maturity profile between locations suggests the influence of site-specific factors. In Sagres and Ria Formosa H. arguinensis individuals were larger and had larger gonads than in Olhos de Agua, which had relatively more immature animals. The spawning and active gametogenesis periods were also longer in Sagres, possibly linked to specificity of food availability and tidal conditions. Ria Formosa also had larger H. mammata individuals with larger gonads than in Murcia and Olhos de Agua, possibly reflecting differences in feeding activity in different substrates (muddy/sandy vs rocky). Gametogenesis in H. arguinensis may be triggered by decreasing photoperiod and temperature, and spawning by increasing temperature. Altogether, these results, which include fecundity and size at first maturity, provide an important basis for the scientific management of sea cucumber fisheries in the region. (C) 2017 Elsevier B.V. All rights reserved.