Identification of Acetylcholinesterase Receptors in Rotifera

We have identified acetylcholinesterase (AChE) receptors in six freshwater rotifers. Using β-bungarotoxin labelled with fluoresceinisothiocyanate (FITC), muscarinic and nicotinic receptors were found in Brachionus quadridentatus (females and males), Lecane luna, Lecane quadridentata, Plationus patulus, and Rotaria neptunia. Using α-bungarotoxin-FITC, nicotinic receptors were identified in B. quadridentatus, Lecane bulla, L. luna, L. quadridentata, P. patulus and R. neptunia. Concentrations as low as 1.5 nM of β-bungarotoxin, and 5 nM of α-bungarotoxin identified receptors in the digestive tract. Higher concentrations of both toxins identified additional receptors associated with the lorica. A preliminary analysis of fluorescence intensity in L. quadridentata showed that response to α-bungarotoxin increases with age from newborn to 48-h old, but not in older individuals, thus suggesting an increase in binding sites, and possibly in number of nicotinic receptors, during the first 48-h of life. Our study extends the number of rotifer species in which AChE receptors have been reported.