A first insight into haemocytes of Pinctada imbricata radiata: A morpho‐functional characterization

Abstract

The pearl oyster Pinctada imbricata radiata (Leach, 1814), from the Pacific Ocean, was one of the first species to reach via Suez the Mediterranean, colonizing the eastern basin and recently spreading to the western. The species showed to be able to adapt to a wide range of climatic, hydrological, and ecological conditions. Since 2000 it reached the Strait of Messina, where is now infesting the transitional waters of the oriented natural reserve “Laguna di Capo Peloro.” Due to such resistance and adaptation ability, various assays were performed. Haemocyte morpho‐functional aspects were evaluated in haemolymph samples fixed with 1% and 2% glutaraldehyde for optical and electron microscopy (TEM). The following assays were carried out: cell characterization using several dyes, detection of intra‐ and extracellular lipids, the capability of phagocytosis using the yeast Saccharomyces cerevisiae and to produce superoxide anion (O2−). Detection of several enzymes, such as acid and alkaline phosphatase, arylsulfatase, chloro‐acetylesterase and β‐glucuronidase was also assessed. Cell count was demonstrated to be abundant with a mean of 8.263 × 106 mm2 ± 0.935 × 106 (SD). Two main cell populations were noticed: granulocytes and hyalocytes, both competent for phagocytosis, to produce O2−, and characterized by lipids. Based on the granule analysis, enzymatic activity was also demonstrated. The observations under TEM confirmed all the results obtained. This study supports the hypothesis that P. imbricata radiata can be usefully employed as a model organism in environmental biomonitoring. Moreover, since the species represent potential threats to native species and ecosystems, further insights into its biological adaptations in invaded ecosystems are recommended.

Exploring the Impact of Contaminants of Emerging Concern on Fish and Invertebrates Physiology in the Mediterranean Sea

“…Generally, all these pollutants are highly toxic to marine life, through studies showing that they are able to lead to physiological changes, reproductive issues, and even mortality. In the Mediterranean, numerous species are indicated as bio-indicators for the detection of toxic substances in the environment [ 9 , 10 ]. Most of them belong to the invertebrates, such as the mollusc Mytilus galloprovincialis , which, as a benthic filter-feeding organism, is reported to be one of the most appropriate bio-indicators.…”