RELATIONSHIPS BETWEEN EMBRYOLOGICAL AGE, CYTOKINESIS-1 AND THE TIMINGOF PLOIDY MANIPULATIONS IN FISH

The duration of cytokinesis-1 (T), as measured in units of embryologic al age (intervals between consecutive and synchronous mitotic cell div isions), is termed tau(o) and is an important relationship in ploidy m anipulations. T/tau(o) is constant and species specific in teleosts. T iming of shock initiation (tau(s)) for intervention to retain extrusio n of the 2nd polar body (2Pb), or for mitotic (late) intervention, is associated with cytokinesis-1 and can be referenced to tau(o) units. T he present study compares effects of temperature determinants, which d efine T/tau(o) in nine fish species. The temperature dependence of emb ryological age tau(o) is expressed by the equation tau(o) = 10(a) x C- b. The equation corresponds with the Krogh's curve, where the power co efficient b is equal to and replaced by T/tau(o). A standard equation (St) was formulated to calculate T/tau(o) in fish species. The tau(o) equations were compared to the standard equation, using Q(10)-coeffici ents for oxygen demand of fish at four different temperatures: alpha - the temperature limits of the fish's distributional range, beta - the minimum temperature of reproduction as expressed by Krogh's curve, ga mma - the actual temperature of reproduction and theta - the temperatu re at which the T/tau(o)-curve intersects the standard curve.