Metabolic cost of development, regeneration, and reproduction in the planarian Schmidtea mediterranea.

Planaria are known for their ability to completely regenerate upon fissioning or experimental amputation. Yet, metabolic costs of regeneration have not been directly measured in planaria. Our goal was to establish the relationships between oxygen consumption (V̇O2), regeneration, and reproductive mode for asexual and sexual strains of Schmidtea mediterranea. We hypothesized that V̇O 2 would vary by regeneration day for both sexual and asexual S. mediterranea , reflecting different costs of tissue reconstruction, but with an additional cost for regenerating sexual organs. Testes regeneration and body mass, as indicators of regeneration progress, and routine mass-specific V̇O 2 as a function of maturity, regeneration, and reproductive mode, were measured over a 22-day regeneration period. Testes growth was highest in sexually mature adults, ~1/2 that in 14-day post-amputation sexual adults, and not detectable in juveniles and hatchlings. Mass-specific routine V̇O 2 in sexuals was highest in mature controls at ~23 μl O 2 /g/h, but only half that in juveniles, hatchlings, and 14 day post-amputation adults. Both intact and 14-day post-amputation asexuals had a mass-specific routine V̇O 2 of ~10–12 μl O 2 /g/h. The sum of V̇O 2 of all amputated sections was ~100% higher than pre-amputation levels in the first 6 days of regeneration in asexuals, but not sexuals. There was no significant difference in V̇O 2 of head, middle, and tail sections during regeneration. Overall, the highest metabolic costs associated with regeneration occurred during the initial 1–6 days of regeneration in both strains, but regeneration costs for sexual structures were not reflected in major V̇O 2 differences between sexual and asexual strains. [Display omitted] • Little is known of metabolic costs of regeneration in sexual or asexual planaria. • Oxygen consumption of intact planaria and regenerating pieces was measured. • The highest metabolic costs appear in the first 6 days of regeneration. • Metabolic costs are higher in sexually mature planaria with testes. [ABSTRACT FROM AUTHOR]