Corticosteroid biosynthesis in the interrenal cells of the teleost fish, Oreochromis mossambicus

ABSTRACT Using high-performance liquid chromatography (HPLC) in combination with radioimmunoassay, three forms of α-MSH (des-acetyl, mono-acetyl and di-acetyl α-MSH) were separated and identified in tilapia neurointermediate lobes and plasma, and in medium from lobes superfused in vitro. The presence of acetylated forms in lobe extracts indicated that the peptides are acetylated intracellularly. Di-acetyl α-MSH was, especially in comparison with monoacetyl α-MSH, relatively more abundant in lobe extracts than in plasma. This suggests that the three forms of α-MSH are not released according to their relative intracellular abundances. The possibility of regulation of this differential release by dopamine and TRH was investigated, using a microsuperfusion system. Dopamine was a potent inhibitor of α-MSH release, but did not modulate the relative abundance of the different forms of α-MSH released from the MSH cells. TRH was a potent stimulator of α-MSH release. It enhanced in vitro the release of di-acetyl α-MSH more than the release of mono-acetyl α-MSH. Thus tilapia may be able to modulate not only the quantitative but also the qualitative signal from the MSH cells. This might enhance the flexibility of the animals to respond to environmental challenges. Journal of Endocrinology (1991) 129, 179–187

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Effects of osmotic pressure and somatostatin on the cAMP messenger system of the osmosensitive prolactin cell of a teleost fish, the tilapia (Oreochromis mossambicus)

General and Comparative Endocrinology ◽

10.1016/0016-6480(91)90111-i ◽

1991 ◽

Vol 83 (1) ◽

pp. 111-117 ◽

Cited By ~ 26

Author(s):

Lisa M.H. Helms ◽

E.Gordon Grau ◽

Russell J. Borski

Keyword(s):

Osmotic Pressure ◽

Teleost Fish ◽

Oreochromis Mossambicus ◽

Prolactin Cell ◽

Messenger System

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SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157838 ◽

1990 ◽

Vol 48 (3) ◽

pp. 58-59

Author(s):

Daryl A. Cornish ◽

George L. Smit

Keyword(s):

Morphological Characteristics ◽

Oreochromis Mossambicus ◽

Breeding Cycle ◽

Limited Information ◽

North West ◽

The North ◽

Sem And Tem ◽

Sperm Development ◽

Ultrastructural Characteristics ◽

The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

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