The crosslinking of skin collagen in annual fish

Abstract

Annual fish were examined as a model for connective tissue aging studies. The investigations were hampered by difficulties in husbandry and the small amount of connective tissue available from these fish. Furthermore our results with different species varied. The levels of reducible croslinks in collagen in the skin of Nothobranchius guentheri did not decrease over a span of 63 weeks. This is in contrast to our results in various mammalian tissues where the levels of reducible crosslinks decreased during maturation and then remained constant throughout the lifespan. On the other hand there were decreases in the reducible crosslink content of Aphyosemion sjoestedti collagen during a period of rapid growth. This species difference is the only example of a lack of correlation between high levels of reducible crosslinks and continued body growth. The species Pterolebias longipinnis did not reveal mortality or physical changes that would classify it as an annual fish in captivity, and this species was not useful in the present studies. Subpopulation differences, species differences and the variable developmental arrest times of fertilized ova are possible contributory factors for the results observed here. These factors must be more fully explored before annual fish can be established as models for certain aging studies.