Premium
Evidence for modulated free magnesium diffusion into teleost embryos and retention above environmental concentrations
Author(s) -
Shanklin Douglas Radford
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a359-a
Subject(s) - chemistry , magnesium , embryo , diffusion , biophysics , flux (metallurgy) , analytical chemistry (journal) , biology , chromatography , thermodynamics , physics , fishery , organic chemistry
Comparative uptake of Na, Mg, K, Ca was examined in the teleost Fundulus embryo model with emphasis on the anomalous behavior of Mg in artificial seawaters (SW). Ten hour net flux of Na, K, Ca suggested functioning ion channels in embryos with intact ectoderm (Oppenheimer stages 22–27). No Na or K result matched or exceeded the concentration in either isosmotic (balanced with sucrose) or heterosmotic artificial SW. There were two instances of excess Ca, both in the heterosmotic ternary medium NaMgCa (+51.72% in 1.92 SW; +18.97% in 1.0 SW), a probable effect of the absence of K. By contrast, in 15 of 24 media internal magnesium concentration equalled (1) or exceeded (14) the external value (56.2 mM/L). Certain atomic attributes might enable free transectodermal Mg passage: highest ionization potential, largest hydration τ ratio (Samoilov), smallest effective ionized diameter, and in this system, the largest flux difference between the isosmotic and heterosmotic series. Internal Mg levels in 1.92 strength media approximated the surrounding solution, indicative of a free diffusion equilibrium, providing the embryo with Mg reserves for the many energy cycle Mg‐dependent enzymes, likely made possible by programmed delayed differentiation and maturation of transmembrane Mg channels.