Two pathways of C21 steroid biosynthesis in North Sea plaice Pleuronectes platessa: What controls them and what is their function?
Mugnier, C.; Scott, A.P.; Vermeirssen, E.L.M.; Rand-Weaver, M. (2000). Two pathways of C21 steroid biosynthesis in North Sea plaice Pleuronectes platessa: What controls them and what is their function?, in: Norberg, B. et al. (Ed.) Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish, Bergen, Norway, July 4-9, 1999. pp. 173-175
In: Norberg, B. et al. (2000). Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish, Bergen, Norway, July 4-9, 1999. International Symposium on the Reproductive Physiology of Fish, 6. Department of Fisheries and Marine Biology, University of Bergen: Bergen. ISBN 82-7461-048-2. 499 pp., more
In: International Symposium on the Reproductive Physiology of Fish. Museo Nacional de Ciencias Naturales. , more
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| Authors | | Top |
- Mugnier, C.
- Scott, A.P.
- Vermeirssen, E.L.M.
- Rand-Weaver, M.
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| Abstract |
Large amounts of 17,20 ß -dihydroxy-4-pregnen-3-one (17,20 ß -P), 17,21-dihydroxy-4-pregnen-3,20-dione (17,21-P) and their derivatives (3 alpha -OH or 3 ß -OH; 5 ß and sulphated forms) are found in the plasma of spawning male and female plaice. In order to understand what controls them and what their function is, we have fractionated plaice pituitary glands and tested the ability of the fractions to stimulate in vitro 17,20 ß and 17,21 ß steroid production by plaice testes. The two pathways are stimulated by the same pituitary hormones. Secondly, we have investigated the presence of receptors for 17,20 ß -P and 17,21-P in testis and ovary. Preliminary results show that there is no receptor for 17,21-P in the cytosolic fraction of ovary, although a specific receptor to 17,20 ß -P with high affinity (K sub(d) = 0.7 nM) and a low capacity (B sub(max) = 0.007 pmol/mg protein) has been found. In testis, cytosolic receptors for both 17,20 ß -P and 17,21-P have been found. Moreover 5 ß -steroids with 3 alpha -OH and 3 ß -OH are strong competitors. In vivo experiments show that both 17,21-P and 17,20 ß -P increase milt hydration in males implanted with these steroids, and increase the number of ovulated females. |
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