Matlock and Dornfeld 1981

Matlock DB, Dornfeld EJ. 1981. Somatic polyploidy in the marine isopod Idothea wasnesenskii. Comparative Biochemistry and Physiology 69A: 777-781.

These authors examined polyploid somatic tissues in an intertidal isopod with a fun name, using a combination of Feuglen cytophotometry (DNA contents) and Autoradiography (DNA synthesis). They were able to examine three tissues (hepatic cecum, midgut, testis sheath) in adult, juvenile, and “emerger” isopods, except testis tissue in emergers.

Endopolyploidy was found to start first in hepatic cecum, as emergers had very few polyploid cells in their midguts. The pattern of cell ploidy distribution varied between tissues: midgut and cecum cells showed a continuous series of larger cells up to 256C, while testis sheath cells did not exceed 32C, and were distributed discontinuously.

Four hypotheses regarding the intercell synchronisation and duration of DNA synthesis were proposed in the Discussion section, though none of the four could be conclusively rejected based on these data. However, the authors suggest that hypothesis 2, that DNA synthesis is confined to a definite S phase in each cell, but there is no synchrony between cells, is probably correct for the studied tissues in this species. Finally, the authors tentatively suggest that moulting hormones may play a role in stimulating DNA synthesis, a phenomenon that has been partly demonstrated in other contexts in arthropods.