Appts. for screening cpds. for biocidal activity - by measuring effect on the voltage induced migration of nematodes in agar

摘要

Appts. for screening cpds. (I) for biocidal activity is based on inducing and evaluating the forced migration of (I)-treated and untreated nematodes (pref. of the genus Rhabditis). It consists of a 30x20x12 cm (external dimensions) housing on which is a mount which can be moved forward, on rails, by a motor in 1.5mm stages. The mount carries an agar-coated glass plate (9x12 cm) which serves as the nematode migration zone and a d.c. voltage of 50V is applied to the plate. A movable (motor-driven) double arm (the lower branch carrying a light diode and the upper branch a phototransistor) scans the migrating nematodes in a serial manner (i.e. as the mount is advanced in steps). The pulse generated by detection of a nematode is passed to an electronic evaluation system consisting of an amplifier; gating circuit; coupled, monostable multivibrator to produce equal pulse lengths; pulse generating circuit (variable according to the migration distance of the nematodes); a counter; a digital 5-point display plus an output for connection to a computer. The result of the evaluation is displayed as an illuminated no. USE/ADVANTAGE - This appts. allows the degree of injury caused by (I) to be visualised and assessed rapidly. The effects of various (I) concns. can be graded.