Vitamin A1 aldehyde in the eggs of the herring (Clupea harengus L.) and other marine teleosts

In the course of a study of vitamin A in herring, vitamin A ester and alcohol and carotenoids were estimated by our usual method (Thompson, Ganguly & Kon, 1949; Fisher, Kon & Thompson, 1952) in the ovaries of herring of various ages and maturities.This method involves extraction with light petroleum in the presence of ethanol, chro- matography, saponification and measurement of vitamin A by the Carr-Price test.Only small amounts of vitamin A were found, of the order of 0-1O g./g., together with about 1-O,g./g. of caro- tenoids, mostly xanthophylls.Scheunert & Schie- blich (1934), using a rat-growth method and the cure of xerophthalmia, showed that the gonads of female herring contain substantial amounts of vitamin A, and Junker (1952-53), with the vaginal- smear assay, found 1-11 tg. of vitamin A/g. of herring ovary, depending on the maturity of the fish.The higher concentrations were in herring about to spawn or spawning.Junker (1956) has also shown that the hard roes of many other fishes contain substantial amounts of vitamin A detect- able by biological assay.We therefore carried out biological and chemical assays of the vitamin A activity of further samples from ripe and running fish of herring hard roe, which consists essentially of unfertilized eggs, and found that the biological activity, determined by the chick liver-storage method, was some ten times that chemically determined.This paper deals with the investigation of the discrepancy, which proved to be due to the presence in the eggs of vitamin Al aldehyde, not estimated in our routine chemical method.Two preliminary reports have already been published (Fisher, Harrison, Kon, Plack, Thompson & Todd, 1956a; Plack, Thompson & Kon, 1957).EXPERIMENTAL MaterialsHerring eggs.Quick-frozen herring were purchased from a Reading fishmonger.The fish were caught off East Anglia in the autumn fishery and were mostly ripe and running.They were thawed by immersing in warm water * Grant-aided by the Development Fund.and sexed by squeezing the fish and observing whether eggs or milt were extruded.The males and immature females were discarded and the roe was removed from the remaining females through a ventral cut.Care was taken to exclude portions of the intestine or other organs.Except for batch C, the roes were blended in an Ato-Mix blender (Measuring and Scientific Equipment Ltd.) in an atmosphere of nitrogen and each batch was thoroughly mixed before storage at -200 in polythene bottles or bags.With batch C, each roe was cut into 16 pieces of about equal size and distributed amongst 16 polythene bottles, the contents of each being mixed by blending before use.The following table shows the dates of purchase of the different batches and the year of catch: Batch