ACETYLCHOLINE AND ACETYLCHOLINESTERASE ACTIVITY IN EARLY EMBRYOS OF THE MEDAKA ORYZIAS LATIPES, A TELEOST

Abstract

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, as authentic acetylcholine in three solvent systems. The amount of acetylcholine in blastulae is about 4 picomoles/embryo.

Location and activities of acetylcholinesterase and butyrylcholinesterase in the rat and human placenta

“…Both enzymes have been described in tissues during development (Drews et al 1966;Fluck 1978), and there is evidence for a transient presence of BChE in some embryonic cells where it can sometimes be replaced by ACHE. For instance neuroblasts express BChE before they abruptly accumulate AChE (Layer 19891).…”

Cholinergic and catecholaminergic receptors in the Xenopus oocyte membrane

“…Transmitters and their receptors in gametes of animals Since the early work of Numanoi (1953Numanoi ( , 1955a ACh and some amines, which act as transmitters at chemically operated synapses, have been found in various animal phyla in oocytes and eggs (Chino, 1957;Buznikov & Chudakova, 1963;Buznikov, 1966;Reshetnikova, 1970;Robbins & Molenaar, 1981); in sperm (Numanoi, 1953;Bishop, Sastry & Stavinoha, 1977;Robbins & Molenaar, 1981) and in embryos (Leonov & Budantsev, 1971;Fluck, 1978). Moreover, cholinesterase has also been found in some of these preparations (Numanoi, 1953;Mehrotra, 1960;Nelson, 1978); and some evidence suggests that sea urchin sperm have nicotinic ACh receptors (Nelson, 1976) and hamster sperm has both a-and /3-adrenergic receptors (Cornett & Meizel, 1978).…”

Microinjection of cyclic ADP-ribose triggers a regenerative wave of Ca2+ release and exocytosis of cortical alveoli in medaka eggs

“…Methods for removing gonads have been previously described (Yamamoto, 1967;Kirchen & West, 1976;Fluck, 1978;Abraham et al, 1993). Gonads and gamates were placed in the same BSS used in other studies of the fertilised medaka egg (Fluck et al, 1991(Fluck et al, , 1992Abraham et al, 1993): 111 mM NaCl, 5.37 mM KCl, 1.0 mM CaCl 2 , 0.6 mM MgSO 4 , 5 mM HEPES pH 7.3.…”