Cellular osmoregulation of the ark clam (Anadara kagoshimensis) hemocytes to hyposmotic media

Abstract

Many bivalve species are considered to be euryhaline organisms due to effective adaptation to fluctuations of environmental salinity. Cellular mechanisms responsible for tolerance to salinity changes remain unclear for bivalves despite this question being critically important for commercially cultured species frequently introduced into regions differing from natural habitat by salinity regime. In the present work laser diffraction method was used for the analysis of volume changes in hemoglobin‐containing ark clam (Anadara kagoshimensis) hemocytes following hyposmotic stimulation. Hemocytes responded to hyposmotic shock (decrease of media osmolarity from 461 to 216 mОsm/L) by a rapid swelling up to 171.5 ± 15.2% of control level. At normal osmotic conditions (osmolarity 461 mOsm/L), hemocyte mean cellular volume (MCV) was 354.0 ± 24.4 fl and maximum MCV of hyposmotically swollen cells prior lysis was 555.5 ± 57.4 fl (at the osmolarity 194 mOsm/L). Ark clam hemocytes demonstrated volume recovery response following hyposmotic swelling. Regulatory volume decrease (RVD) reaction did not depend on hemoglobin confirmation status. Final MCV of swollen hemocytes at the end of experimental period of RVD in oxygenated and deoxygenated suspensions did not significantly differ.

Effects of Salinity on Hemocyte Functionality in Mediterranean Mussels (Mytilus galloprovincialis)

“…Changes in phagocytic activity may be associated with alterations in hemocyte shape and morphology resulting from osmotic volume changes of hemocytes. However, we did not observe substantial changes in hemocyte morphology either at hyposalinity or hypersalinity stress indicating that mussels possess cellular volume osmoregulatory mechanisms, such as regulatory volume decrease following hypoosmotic swelling and regulatory volume increase in response to osmotic shrinkage (Bregante et al 2016, Kladchenko et al 2022. Suppression of phagocytosis observed at salinity stress may occur due to general decrease of ATP production in hemocytes because phagocytosis is an energy-demanding process for both vertebrate and invertebrate organisms (Coyne 2011, He et al 2019, Lochmiller & Deerenberg 2000.…”

Parámetros hemocitarios y química de la hemolinfa en reproductores de la concha prieta Anadara tuberculosa (Arcoida: Arcidae)

“…Posiblemente esta capacidad de los hemocitos pueda garantizar la supervivencia en medios de cambios de salinidad temporales. Kladchenko et al (2022) reportan tolerancia de salinidades menores a 7‰ en hemocitos de A. kagoshimensis. También, se conoce que la fragilidad de las células sanguíneas puede aumentar por la edad, contaminación y daño celular (Orbach et al 2017).…”

“…El estado fisiológico de los animales de cultivo puede ser determinado a través de parámetros hematológicos y bioquímicos de su hemolinfa, los cuales son de importancia crítica en el diagnóstico de diversas condiciones fisiopatológicas (Reshma et al 2020, Nabi et al 2022. Las cantidades, distribución, tipos y diámetro de hemocitos son índices sencillos, económicos y de fácil interpretación para estimar la salud animal (Zapata- Vívenes et al 2012, Loján et al 2021, Kladchenko et al 2022. Sin embargo, no existen registros de los valores referenciales normales de la mayoría de los animales y en particular de bivalvos.…”