Kelly McCullough dissecting subumbrellar muscle from
the mesopelagic jellyfish Periphylla periphylla.
CLICK HERE for another picture of Periphylla periphylla.
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
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.