Citation:

Antonette, M., R. Juinio, J. Cobb, D. Bengston, AND M. Johnson. CHANGES IN NUCLEIC ACIDS OVER THE MOLT CYCLE IN RELATION TO FOOD AVAILABILITY AND TEMPERATURE IN HOMARUS AMERICANUS POSTLARVAE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-93/137 (NTIS PB93185841), 1992.

Description:

Postlarval lobsters Homarus americanus Milne Edwards hatched from three females collected in 1989 fr m Block Island Sound, Rhode Island were reared individually in the laboratory under nine treatment combinations of temperature (15, 18 and 200C) and feeding(starved, low ration, and full ration). otal RNA, DNA(mg. ind.-1), RNA:DNA ratios and molt stage were determined for individuals sampled at daily intervals. ostlarval lobsters had high resistance to starvation. ajority of the lobsters survived 12d of food deprivation, with some surviving up to 24d. uring starvation, cell biomass (estimated from protein:DNA) decreased to a minimum size, whereas cell number (based on total DNA)was generally conserved. he molt cycle was arrested at stage C in the starved postlarvae. nstar duration was inversely related to temperature. owever, the duration of the postlarval instar did not differ between the low and full ration treatments. ncoupling of the cell growth and the molt cycle was evident in the full and low ration treatments. n the full ration treatments, the postmolt through early premolt was characterized by a rapid increase in total RNA and DNA. aximum cell bio-mass was attained by molt stage C or Do. In the low ration treatments, total RNA and DNA were less than those in the full ration treatments, and the maximum cell biomass was attained only at molt stage D2-3. otably, different feeding regimes resulted in different patterns in RNA:DNA ratios over the molt cycle during the post-larval instar. Results indicate that molt cycle and temperature must be considered when estimatingnutritional state in postlarval lobsters.

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