Anatomical and histological characteristics of the nervous system of the Chilean giant mussel, Choromytilus chorus (Molina 1782) (Bivalvia, Mytilidae) / Características anatómicas e histológicas del sistema nervioso del mejillón gigante, Choromytilus chorus (Molina 1782) (Bivalvia, Mytilidae)

The anatomy and histology of the nervous system in the mussel Choromytilus chorus were studied. Juvenile specimens of C. chorus and adult broodstock were collected in Laraquete Cove, Chile (37°09'S; 37°11'O). The juveniles were used for histological analysis and the adults for a macroscopic description of anatomical. The histological description was carried out by Gallego´s trichrome technique. The macroscopic analysis showed that nervous system network includes three pairs of ganglia of orange color and little size (20-40 mm) (cerebral, pedal and visceral) located in the anterior, middle and posterior zone of the specimen, respectively. The histological analysis showed many type de cells inside the ganglia (neurosecretory, granulated and glial cells). The ganglia network could be involving in regulating several physiological processes in the mussels through of their neurosecretions.

Se estudió la anatomía e histología del sistema nervioso en el coro Choromytilus del mejillón. Se recolectaron especímenes juveniles de C. coros y reproductores adultos en Laraquete Cove, Chile (37 ° 09'S, 37 ° 11'O). Los especímenes juveniles se utilizaron para el análisis histológico y los adultos para una descripción macroscópica de anatómica. La descripción histológica se realizó mediante la técnica de tricrómico de Gallego. El análisis macroscópico mostró que la red del sistema nervioso incluye tres pares de ganglios de color naranjo y poco tamaño (20-40 mm) (cerebral, pedal y visceral) localizados en la zona anterior, media y posterior de la muestra, respectivamente. El análisis histológico mostró muchos tipos de células dentro de los ganglios (células neurosecretoras, granuladas y gliales). La red de ganglios podría estar involucrada en la regulación de varios procesos fisiológicos en los mejillones a través de sus neurosecreciones.

Transgenerational Effects of pCO2-Driven Ocean Acidification on Adult Mussels Mytilus chilensis Modulate Physiological Response to Multiple Stressors in Larvae.

The effect of CO2-driven ocean acidification (OA) on marine biota has been extensively studied mostly on a single stage of the life cycle. However, the cumulative and population-level response to this global stressor may be biased due to transgenerational effects and their impacts on physiological plasticity. In this study, we exposed adult mussels Mytilus chilensis undergoing gametogenesis to two pCO2 levels (550 and 1200 µatm) for 16 weeks, aiming to understand if prolonged exposure of reproductive individuals to OA can affect the performance of their offspring, which, in turn, were reared under multiple stressors (pCO2, temperature, and dissolved cadmium). Our results indicate dependence between the level of pCO2 of the broodstock (i.e., parental effect) and the performance of larval stages in terms of growth and physiological rates, as a single effect of temperature. While main effects of pCO2 and cadmium were observed for larval growth and ingestion rates, respectively, the combined exposure to stressors had antagonistic effects. Moreover, we found a suppression of feeding activity in post-spawning broodstock upon high pCO2 conditions. Nevertheless, this observation was not reflected in the final weight of the broodstock and oocyte diameter. Due to the ecological and socioeconomic importance of mussels' species around the globe, the potential implications of maternal effects for the physiology, survival, and recruitment of larvae under combined global-change stressors warrant further investigation.

Vitellogenin of the Chilean flounder Paralichthys adspersus as a biomarker of endocrine disruption along the marine coast of the South Pacific. Part I: induction, purification, and identification.

We sought to provide a useful indicator of the presence of endocrine-disrupting contaminants along the marine coast of the South Pacific using Chilean flounder (Paralichthys adspersus). In light of the lack of information on vitellogenin for this species, we induced, purified, and identified the plasma vitellogenin of Chilean flounder inhabiting the Chilean coast. Vitellogenin (Vg) from Chilean flounder was purified by size exclusion and ion-exchange chromatography using plasma from juvenile males induced by injecting 17beta-estradiol. The Vg was detected by SDS-PAGE and Western blot analyses using an antibody against turbot (Scophthalmus maximus) vitellogenin. These analyses revealed a protein band of 205 kDa and three minor bands of 120, 90, and 68 kDa. These proteins were identified as Vg by means of mass spectrometry (LCQ Duo ESI-IT-MS), matching sequences of tryptic peptides to known sequences for several other fish species. The matches showed the presence of vitellogenin (VgI, VgII, Vg A and Vg B) in Chilean flounder, similar to species such as mummichog (Fundulus heteroclitus), Japanese medaka (Oryzias latipes), and white perch (Morone americana). These results are discussed in terms of identifying Vg in Paralichthys adspersus with the antibody to turbot Vg. Moreover, we compare the molecular size of Vg from Chilean flounder (large) with that of other flatfish species. Finally, we discuss the potential use of this molecule as a biomarker for the presence of xeno-estrogenic compounds along the Chilean coastline.

Diseases of the Chilean flounder, Paralichthys adspersus (Steindachner, 1867), as a biomarker of marine coastal pollution near the Itata River (Chile): Part II. Histopathological lesions.

This study evaluated the histopathological lesions of the Chilean flounder, Paralichthys adspersus, inhabiting the marine coastal area influenced by the Itata River (central Chile) in order to provide an environmental baseline given the plans to discharge effluents from a cellulose plant through a submarine pipe in the area. Flounder were also sampled at two reference sites over the course of 1 year. Pathological examinations and descriptions of histopathological lesions follow the ICES suggested protocol: internal and histopathological lesions, condition factor, and hepatosomatic and spleen indexes. The prevalence of fish with histopathological lesions differed significantly among sites. The flounder sampled in the Itata area were the most affected. Evaluation of histopathological lesions observed on the flounder caught in the Itata area revealed (i) 16 different types of histopathological lesions, (ii) a high prevalence of lesions in gills and epidermal and hepatic tissue, and (iii) a normal K factor and hepatosomatic index. Significant differences were found in epidermal hyperplasia (EH), chronic dermatitis, telangiectasis (TEL), localized edema in the base of lamellae (LE), fusion of secondary lamellae (FSL), foci of cellular alteration (FCA), melanomacrophagic centers (MMCs), and hemosiderin (HEM) lesions among sites and among sites by season of the year. Winter 2006 was the most affected. A seasonal analysis of histopathological lesions on flounder caught in the Itata area showed significant differences for EH, progressive focal invasion of muscle fibers (PFIMF), TEL, LE, FSL, lamellar bifurcation, hepatitis, FCA, MMCs, and HEM lesions between the sampled seasons of the year; flounder caught in winter 2006 had the highest prevalence of these lesions except for PFIMF, which was higher in winter 2007. These results are discussed in relation to the contents of inorganic and organic compounds in the water column and the contents of organic compounds in sediments of the subtidal environment in the Itata area.

Diseases of the Chilean flounder Paralichthys adspersus (Steindachner, 1867) as biomarkers of marine coastal pollution near the Itata River (Chile). Part I: in situ macroscopic lesions.

This study evaluated the health of the Chilean flounder Paralichthys adspersus inhabiting the marine coastal area influenced by the Itata River. Flounder were also sampled at two reference sites during the course of 1 year. The pathological examination was done following the ICES protocol: external and internal lesions, condition factor, hepatosomatic and spleen indexes, and number of erythrocytes, lymphocytes, and thrombocytes. The prevalence of fish with lesions differed significantly among sites. The flounder sampled in the Itata area were the most affected. The evaluation of the macroscopic lesions observed on the flounder caught in the Itata area revealed (1) seven different types of macroscopic lesions, (2) a high prevalence of epidermal irritation lesions, and (3) a normal K factor, hepatosomatic index, and blood cell count. Significant differences were found in epidermal irritation lesions between stages and sites and between sexes and sites. Juveniles and adults as well as males and females were affected. A seasonal analysis of the macroscopic lesions on the flounder caught in the Itata area showed significant differences for only the epidermal irritation lesions between the sampled seasons of the year; the flounder caught in winter 2006 had the highest prevalence (77%) of such lesions. These results are discussed in relation to the hydrographic conditions, the contents of inorganic, nutrient and other organic compounds in the water column, and the contents of organic compounds and metals in the sediments of the subtidal environment in the Itata area.