Cytochemical investigation of the digestive gland of two strombidae species (Strombus gigas and Strombus pugilis) in relation to the nutrition

The Queen Conch (Lobatus gigas) Proteome: A Valuable Tool for Biological Studies in Marine Gastropods

Queen conch (Lobatus gigas) is a marine gastropod endemic to the Caribbean. This species is a cultural symbol, being a significant local food source and the second largest commercial fishery in the region. However, over-exploitation and natural habitat degradation have exerted high survival pressure on this species. This work aims to provide novel proteomic data to highlight the metabolism of the species and to provide an important tool for the understanding of queen conch biology and physiology. Herein, we profiled the whole proteome from 3 organs (gills, digestive gland and muscle) of L. gigas combining gel-free and gel-based techniques. Overall 420 clusters of proteins were identified corresponding to the minimum identification requirement of protein sequence redundancy. Gene ontology and KEGG analysis highlighted 59 metabolic pathways between identified proteins. The most relevant routes according to the number of sequences found per pathway were purine and thiamine metabolism, closely related to nucleotide and carbohydrate metabolism. We also emphasize the high number of proteins associated to the biosynthesis of antibiotics (93 proteins and a total of 28 enzymes), which were among the top-twenty pathways identified by KEGG analysis. The proteomics approach allowed the identification and description of putative markers of oxidative stress, xenobiotic metabolism, heat shock response and respiratory chain for the first time in the species, which could be extremely useful in future investigations for diagnosing and monitoring L. gigas population health.

The potential role of spherocrystals in the detoxification of essential trace metals following exposure to Cu and Zn in the fighting conch Strombus (Lobatus) pugilis

Crypt cells-one of the three cell types composing Strombidae digestive tubules-are characterized by the presence of numerous metal-containing phosphate granules termed spherocrystals. We explored the bioaccumulation and detoxification of metals in Strombidae by exposing wild fighting conch Strombus pugilis for 9 days to waterborne CuSO₄ and ZnSO₄. The total amount of Cu and Zn was determined in the digestive gland and in the rest of the body by Inductively Coupled Plasma (ICP) analyses. The digestive gland spherocrystal metal content was investigated based on the semi-quantitative energy dispersive X-ray (EDX) elemental analysis. ICP analyses of unexposed individuals revealed that 87.0 ± 5.9% of the Zn is contained in the digestive gland, where its concentration is 36 times higher than in the rest of the body. Regarding Cu, 25.8 ± 16.4% of the metal was located in the digestive gland of the control individuals, increasing to 61.5 ± 16.4% in exposed individuals. Both Cu and Zn concentrations in the digestive gland increased after exposures, pointing to a potential role of this organ in the detoxification of these metals. EDX analysis of spherocrystals revealed the presence of Ca, Cl, Fe, K, Mg, P, and Zn in unexposed individuals. No difference was found in the relative proportion of Zn in spherocrystals of exposed versus control individuals. Contrastingly, copper was never detected in the spherocrystals from controls and Zn-exposed individuals, but the relative proportion of Cu in spherocrystals of Cu-exposed individuals varied from 0.3 to 5.7%. Our results show the direct role of spherocrystals in Cu detoxification.