ISSN:
1432-0878
Keywords:
Gonadotropin
;
Gonadotropin subunits
;
Gonadotropes
;
In situ hybridization
;
Immunocytochemistry
;
Pituitary gland, pars distalis
;
Oogenesis
;
Oncorhynchus mykiss (Teleostei)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Biosynthesis of salmon gonadotropins, GTH I and GTH II, during ovarian development, were examined by means of in situ hybridization histochemistry and indirect immunocytochemistry. In rainbow trout pituitary glands, expression of GTH Iβ- and IIβ-subunit genes appeared separately in distinct cells (GTH I- and GTH II-cells), whereas the GTH α-subunit gene was expressed in both cell-types. In the GTH I-cells, coordinated increases in GTh, α and Iβ messenger ribonucleic acids (mRNAs) occurred coincident with the onset of vitellogenesis, indicating active synthesis of GTH I during vitellogenesis. In contrast, in the GTH II-cells, both GTH α-and IIβ-mRNA signals markedly increased from a later stage of vitellogenesis and persisted throughout oocyte maturation and ovulation, supporting the idea that GTH II is actively synthesized as a maturational GTH. GTH α-mRNA levels in the GTH I-cells selectively decreased prior to final oocyte maturation, although Iβ-mRNA levels remained elevated, thus suggesting a decline of biosynthesis of GTH I after vitellogenesis. These findings clarify how the synthesis of GTH I and GTH II are coordinated in the piscine pituitary, and indicate that the expression of GTH subunit genes during gametogenesis is regulated differentially in a cell-specific manner, both temporally and spatially.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00318586
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