HETEROPLOIDY IN TRITURUS TOROSUS. II. THE INCIDENCE OF CHROMOSOMAL VARIATIONS IN SHIPPED LARVAE

¹ University of North Carolina

1. Tail-tips from Triturus torosus larvae subjected to shipment by Railway Express have been studied cytologically.

2. A total of 838 "first" tips was examined. Of these, 381 (45.5%) were normal diploids, 359 (42.8%) had nuclei of variable size and/or variations in nucleolar number, 75 (8.9%) had abnormal mitoses, and 23 (2.7%) were chromosomal mosaics.

3. Of the 607 regenerated "second" tips studied, 240 (39.5%) were normal diploids, 188 (30.9%) had nuclei of variable size and/or variations in nucleolar number, 94 (15.5%) had abnormal mitoses, and 85(14.0%) were chromosomal mosaics.

4. Three hundred fifty-six second regenerates ("third" tips) were examined. Among these, 153 (43.0%) were normal diploids, 159 (44.6%) had nuclei of variable size and/or variations in nucleolar number, 32 (9.0%) had abnormal mitoses, and 12 (3.4%) were chromosomal mosaics.

5. The following types of mosaics were found: haploid/diploid; hypodiploid/diploid; hypodiploid/diploid/hyperdiploid; hypodiploid/diploid/tetraploid; diploid/hyperdiploid; diploid/triploid; diploid/tetraploid; diploid/pentaploid; diploid/hexaploid; diploid/octaploid; diploid/triploid/tetraploid; diploid/tetraploid/pentaploid; diploid/tetraploid/hexaploid; diploid/triploid/tetraploid/pentaploid; diploid/hyperdiploid/tetraploid. These mosaics were predominantly diploid, with, for the most part, isolated heteroploid cells in scattered areas.

6. Seventeen instances of multipolar anaphases and telophases were found in the tail-tips from these shipped larvae. Seven of these were tripolar and 10 were tetrapolar.