Triploidy induced by cold shock in cyprinid loach, Misgurnus anguillicaudatus. In：J.L. Maclean, L.B. Dizon and L.V. Hosillos (eds.)

Abstract

Optimum conditions for induction of triploidy by cold shock in the cyprinid loach, Misgurnus anguillicaudatus, were studied. Triploids were identified by measuring the DNA content of erythrocytes with microscope cytophotometry. When eggs were subjected to cold shock (8°C for 40 min.) at various times after fertilization, those shocked at 5 mire. after fertilization produced the highest proportion of triploid fry. One hundred per cent triploids were produced in the groups, treated at l°C for 30-40 min. Hatching rate decreased and the proportion of deformed fry increased as cold shock duration was increased. The proportion of triploids tended to decrease as the temperature of cold shock increased from 1 to 12°C.