Preferential Segregation of the Fourth Chromosomes in Drosophila melanogaster

Abstract

A fragment made up of the left end of X and the spindle-attachment of the 4th chromosome was studied in hyper-ploids that also carried 2 normal 4''s. At reduction, the fragment goes more often with certain 4''s than with others. All tested 4''s could be arranged in a series, such that each is "preferred" (by the fragment) to any chromosome lying below it in the seriation. The same seria-tion applies to triplo-4 flies (with no fragment), in that a chromosome near the top of the series goes to the diplo-4 pole more often than to the haplo-4 pole; one near the bottom of the series more often to the haplo-4 pole.