Changes in Nucleic Acids over the Molt Cycle in Relation to Food Availability andTemperature in 'Homarus americanus' Postlarvae

摘要

Postlarval lobsters Homarus americanus, hatched from three females collected in1989 from Block Island Sound, Rhode Island were reared individually in the laboratory under nine treatment combinations of temperature (15, 18 and 20C) and feeding (starved, low ration, and full ration). Total RNA, DNA(mg./ind.), RNA:DNA ratios and molt stage were determined for individuals sampled at daily intervals. Post-larval lobsters had high resistance to starvation. A majority of the lobsters survived 12d of food deprivation, with some surviving up to 24d. During starvation, cell biomass (estimated from protein:DNA) decreased to a minimum size, whereas cell number (based on total DNA) was generally conserved. The molt cycle was arrested at stage C in the starved postlarvae. Instar duration was inversely related to temperature. However, the duration of the postlarval instar did not differ between the low and full ration treatments. Uncoupling of the cell growth and the molt cycle was evident in the full and low ration treatments.