Kelly McCullough dissecting subumbrellar muscle from
the mesopelagic jellyfish Periphylla periphylla.
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Research Abstract

We have investigated the scaling of the glycolytic enzyme lactate dehydrogenase (LDH) and the Krebs cycle enzyme citrate synthase (CS) in the swimming muscle and tentacle tissue of the mesopelagic coronate scyphomedusa Periphylla periphylla and the bathypelagic narcomedusa Aegina citrea. The scaling of these enzymes along with total protein was investigated in whole homogenates of the surface living scyphomedusa Aurelia aurita. Weight-specific LDH activities in swimming muscle showed positive scaling in relation to body size in P. periphylla collected off California and Hawaii. Weight-specific LDH activities in tentacles only increased with regards to increasing mass in P. periphylla collected off California. The LDH values of the scaling coefficient, b, in swimming muscle and tentacle were higher in P. periphylla collected in the low oxygen waters off California that from those collected off the Hawaiian Islands in a higher oxygen environment. CS activity showed no significant effect of size in any of the medusae investigated except for that of tentacle tissue in Hawaiian P. periphylla. LDH showed a significant decrease with body size in A. citrea swimming muscle and in Aurelia aurita whole animal homogenates. We conclude that positive scaling of LDH in P. periphylla is in response to extra energy used during vertical migration through the water column, and that there is likely increased glycolytic energy demand due to low O2 concentration limiting aerobic energy supply due to decreased oxygen diffusion under lower oxygen tensions off California.