Abstract
The zebrafish Danio rerio is a teleost model species widely used in developmental genetics, biomedical studies, toxicology, and drug screening. Despite the interest of this species in research, little is known through indirect observations about its blood osmolality, which is a key parameter for diverse experiments. In this study, we directly measured blood osmolality using nano-osmometry at different stages of zebrafish postembryonic development. We found that blood osmolality is close to 240 mOsm·kg−1 in early larvae. It progressively increased to ∼270 mOsm·kg−1 during the larval development before reaching ∼300 mOsm·kg−1 after metamorphosis in juveniles and later in adults. These ontogenetic changes in blood osmolality illustrate the physiological changes in osmoregulation associated with postembryonic development, including metamorphosis. These values are of practical interest for adjusting the osmolality of fixatives and cell and tissue culture media for research using zebrafish as a model.
Highlights
The zebrafish Danio rerio (Buchanan-Hamilton 1822) is a stenohaline freshwater teleost (Cyprinidae)
As the results reported above for D. rerio are scarce in a limited number of stages, the objective of the present study was to directly measure the values of blood osmolality during the entire postembryonic development of the zebrafish, using nano-osmometry that allowed to collect individual data in all stages but the smallest one tested
Blood osmolality increased during the postembryonic development from larvae to juveniles and adults of D. rerio (Table 2 and Fig. 1)
Summary
The zebrafish Danio rerio (Buchanan-Hamilton 1822) is a stenohaline freshwater teleost (Cyprinidae). Its main natural range covers the Ganges and Brahmaputra River basins in India, Bangladesh, and Myanmar where it is typically found in slow-moving or standing water bodies.[1] Exported over a century ago, it became a common aquarium species easy to culture. This feature and other traits such as small size, rapid development, optical transparency of early embryos, availability of genetic databases, and applicability of molecular tools, have made the zebrafish a key model for developmental genetics, toxicology, drug screening, and biomedical studies, including cancer, host–pathogen interactions and regenerative medicine. In later stages of development, it has been shown that adult zebrafish can regulate plasma and whole-body electrolyte concentrations,[7] from soft waters with low ion concentrations (Na+: 35 lM; Cl-: 43 lM) to hard water (Na+: 1480 lM; Cl-: 1625 lM), with corresponding osmolalities of 0.1 to 7–10 mOsm$kg-1
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