Cargando…

THE VITAMIN A OF THE LOBSTER

In many crustacea, including the lobster, the bulk of the vitamin A of the whole animal is concentrated in the eyes. Recently Fisher, Kon, and Thompson found that vitamin A extracted from the eyes of euphausiid crustacea has only about one half the biological potency of the same amount of the all-tr...

Descripción completa

Detalles Bibliográficos
Autores principales: Wald, George, Burg, Stanley P.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1957
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2147639/
https://www.ncbi.nlm.nih.gov/pubmed/13416534
_version_ 1782144486650937344
author Wald, George
Burg, Stanley P.
author_facet Wald, George
Burg, Stanley P.
author_sort Wald, George
collection PubMed
description In many crustacea, including the lobster, the bulk of the vitamin A of the whole animal is concentrated in the eyes. Recently Fisher, Kon, and Thompson found that vitamin A extracted from the eyes of euphausiid crustacea has only about one half the biological potency of the same amount of the all-trans acetate or fish liver vitamin A. In the present experiments the vitamin A of the lobster eye is found to consist almost entirely of the hindered cis isomer, neo-b, the precursor in the vertebrate retina of the visual pigments rhodopsin and iodopsin. This isomer is known to have a low biological potency in the rat, only about one quarter that of all-trans vitamin A. In the lobster eye it is virtually all extractable with petroleum ether, about 30 per cent in the form of free alcohol, about 70 per cent in the form of esters. It was identified by its absorption spectrum, as derived from measurements on crude extracts, and measured directly in purified preparations; the changes in absorption which accompany isomerization; oxidation to the corresponding retinene; and synthesis from the latter of rhodopsin. The examination of an extract of euphausiid eyes, provided by Dr. Kon, also revealed the presence of neo-b vitamin A virtually alone. This may be the characteristic condition in the eyes of Eucarid crustacea. It is peculiar in that the neo-b isomer, being a sterically hindered form, is ordinarily expected to be represented in any equilibrium mixture of geometric isomers in very small amount. Apparently certain crustacea have ways of circumventing the difficulties implicit in producing and retaining this isomer, and store it in the eye virtually alone.
format Text
id pubmed-2147639
institution National Center for Biotechnology Information
language English
publishDate 1957
publisher The Rockefeller University Press
record_format MEDLINE/PubMed
spelling pubmed-21476392008-04-23 THE VITAMIN A OF THE LOBSTER Wald, George Burg, Stanley P. J Gen Physiol Article In many crustacea, including the lobster, the bulk of the vitamin A of the whole animal is concentrated in the eyes. Recently Fisher, Kon, and Thompson found that vitamin A extracted from the eyes of euphausiid crustacea has only about one half the biological potency of the same amount of the all-trans acetate or fish liver vitamin A. In the present experiments the vitamin A of the lobster eye is found to consist almost entirely of the hindered cis isomer, neo-b, the precursor in the vertebrate retina of the visual pigments rhodopsin and iodopsin. This isomer is known to have a low biological potency in the rat, only about one quarter that of all-trans vitamin A. In the lobster eye it is virtually all extractable with petroleum ether, about 30 per cent in the form of free alcohol, about 70 per cent in the form of esters. It was identified by its absorption spectrum, as derived from measurements on crude extracts, and measured directly in purified preparations; the changes in absorption which accompany isomerization; oxidation to the corresponding retinene; and synthesis from the latter of rhodopsin. The examination of an extract of euphausiid eyes, provided by Dr. Kon, also revealed the presence of neo-b vitamin A virtually alone. This may be the characteristic condition in the eyes of Eucarid crustacea. It is peculiar in that the neo-b isomer, being a sterically hindered form, is ordinarily expected to be represented in any equilibrium mixture of geometric isomers in very small amount. Apparently certain crustacea have ways of circumventing the difficulties implicit in producing and retaining this isomer, and store it in the eye virtually alone. The Rockefeller University Press 1957-03-20 /pmc/articles/PMC2147639/ /pubmed/13416534 Text en Copyright © Copyright, 1957, by The Rockefeller Institute for Medical Research This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Wald, George
Burg, Stanley P.
THE VITAMIN A OF THE LOBSTER
title THE VITAMIN A OF THE LOBSTER
title_full THE VITAMIN A OF THE LOBSTER
title_fullStr THE VITAMIN A OF THE LOBSTER
title_full_unstemmed THE VITAMIN A OF THE LOBSTER
title_short THE VITAMIN A OF THE LOBSTER
title_sort vitamin a of the lobster
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2147639/
https://www.ncbi.nlm.nih.gov/pubmed/13416534
work_keys_str_mv AT waldgeorge thevitaminaofthelobster
AT burgstanleyp thevitaminaofthelobster
AT waldgeorge vitaminaofthelobster
AT burgstanleyp vitaminaofthelobster