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ACETYLCHOLINE AND ACETYLCHOLINESTERASE ACTIVITY IN EARLY EMBRYOS OF THE MEDAKA ORYZIAS LATIPES , A TELEOST
Author(s) -
FLUCK RICHARD A.
Publication year - 1978
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1978.00017.x
Subject(s) - acetylcholinesterase , acetylcholine , embryo , aché , chemistry , blastoderm , biology , myocyte , biochemistry , anatomy , endocrinology , enzyme , microbiology and biotechnology , embryogenesis
Acetylcholinesterase (AChE) activity is present in homogenates of medaka embryos during cleavage and epiboly. The levels of AChE activity change little during this period of development and are similar in embryos grown at either 15°C or 25°C. The specific activity of AChE in cells isolated from blastulae is 0.06 mmoles substrate hydrolyzed/min/g protein, a value comparable to that of chicken myoblasts and myotubes in vitro . Acetylcholinesterase activity was detected cytochemically in all cells dissociated from blastulae and gastrulae. In deep blastomeres AChE activity is present nearly throughout the cytoplasm; it is absent from peripheral regions of the cytoplasm which are involved in circus, or limnicolor, movements. Acetylcholine‐like activity in extracts of the embryos was assayed using the clam heart ventricle bioassay. The active principle, which caused a decrease in both the frequency and magnitude of ventricular contractions, was inactivated by heating at pH 10 and by incubation at pH 7.0 with commercial AChE. The effect of the active principle on the clam heart was blocked by mytolon chloride, a drug which specifically blocks the effect of acetylcholine on the clam heart. The active principle migrated on Whatman #1 chromatography paper with the same R f as authentic acetylcholine in three solvent systems. The amount of acetylcholine in blastulae is about 4 picomoles/embryo.