Carotenoids

Carotenoid composition, tissue distribution, deposition in the
exoskeleton, and assimilation were studied in the blue crab, Callinectes
sapidus. Carotenoids identified were: alpha-carotene; beta-carotene;
lutein; 'carcinoxanthin'; isocryptoxanthin; echinenenone; canthaxanthin;
astaxanthin; and, astaxanthin esters. Tentative identification was made
for a-carotene, 8-carotene-monoepoxide, and phoenicoxanthin. The
occurrence of 'carcinoxanthin', in high concentration, in antennae and
eyestalks, is noted and discussed. Hepatopancreas yields mainly Bcarotene,
with more oxidized 'intermediates' and astaxanthin being
localized in the hypodermis. Exoskeletal carotenoids, both free and
conjugated to protein, were shown to be bound to chitin. Exoskeletal
carotenoprotein was shown to contain free astaxanthin as the only
carotenoid present. External coloration was analyzed and the underlying
pigments identified. Starved crabs with carotenoid-depleted
hepatopancreas were shown to assimilate beta-carotene, but not astaxanthin,
from test diets. Possible metabolic pathways and functions of
carotenoids in Crustacea are discussed.

Fresh and aged unispecific samples have been analyzed using IP-RPHPLC and PDA in order to reveal the chlorophylls and carotenoids alterations during senescence and death. Aging studies showed that cyanobacterial chlorophyll- a was destroyed faster than carotenoids in room oxic conditions. The reverse was found for the other eukaryotic species. Species with high chlorophyllase activity produced phytol free chlorophyll derivatives during death. The rate of chlorophyll-a destruction was; room oxic > room anoxic > cold anoxic. Pyropheophorbide-a was often the final product of type-I chlorophyll-a degradation. The conversion from fucoxanthin to fucoxanthinol was observed. Chlorophyll-c was found to be destroyed faster than chlorophyll-a. The quantitative relationship of certain "biomarker" pigments (e.g. fucoxanthin, zeaxanthin) to chlorophyll-a was found not to change significantly during the first 1--2 months senescence-death scenarios. This aids the field of chemotaxonomy in that valid estimations may still be made when phytoplankton populations contain senescent individuals.