Separation of chicken adenohypophysial gonadotropins

A stereological study of the different cell populations in chicken testes treated with follicle-stimulating hormone during embryonic development

Quantitative morphological methods were used to analyse the histomorphometric changes and variations in the number and size of cells from diverse cellular populations in testes of newly hatched chicks treated with follicle stimulating hormone (FSH) during embryonic development. The tissue was fixed and embedded in Epon and sections were morphometrically measured under light microscopy, using point counting for volume densities and the Floderus equation to determine numerical density. The average volume of the individual cell was determined by dividing the volume density by the numerical density. Results indicate that FSH administration causes an increase in the number of Sertoli cells and spermatogonia, as well as enlargement of the individual Sertoli cells leading consequently to an increase in the diameter and volume density of the testicular seminiferous tubules. Results also reveal an increase in the volume density of the interstitial cords of the Leydig cells, this expansion is due to the enlargement of the individual Leydig cells and not to an increase in their number, which remains constant. We conclude that testes of chick embryos are able to respond to FSH treatment, as revealed by the changes in the number and size of the cells conforming the diverse cellular populations of the testis. FSH treatment during embryonic development induces histomorphometric changes in both the interstitial tissue and seminiferous tubules, accelerating their growth and differentiation.

The molecular biology of avian gonadotropin

Complimentary DNA for precursor molecules of chicken and quail luteinizing hormone (LH) beta subunits have cloned. From nucleotide sequences of the cDNA, the primary structures of the LH beta subunit molecules of these avian species were deduced. The primary structures were similar, the amino acid sequence homology being 91.6%. For the alpha subunit, cloning of cDNA has been performed also in these two avian species. Predicted primary structures of the alpha subunit molecules of these birds were completely identical, although nucleotide sequences of their cDNA were slightly different. The LH beta subunit molecules of both birds had 15 Pro residues at the same positions. Ten of them shared the same positions with Pro residues in the mammalian LH beta subunits, in which about 20 Pro residues exist. Prediction of the secondary structure and exposure of each amino acid residue in the chicken LH beta subunit molecule were performed with the aid of a computer program for protein engineering. It was revealed that most of 15 Pro residues did not exist in regions where the beta structure was predicted but were distributed in regions where a turn or loop was predicted. In addition, three of four Tyr residues were predicted to be located inside the molecule. These results suggest that the predicted presence of a number of Pro residues in the loop of the secondary structure is a cause of high animal group and hormone specificities in the LH-LH receptor interaction. The predicted internal localization of Tyr residues is considered to cause loss of receptor binding activity by conventional radioiodination procedures.

Induction of ovarian growth and ovulation by administration of a chicken gonadotrophin preparation to Japanese quail kept under a short-day regimen

1. Chronic administration of a glycoprotein fraction from chicken pituitary using an ALZET osmotic pump at 12.5 micrograms/h for 2 weeks induced growth of ovarian follicles to a mature size in the ovary and deposition of yolk in sexually immature 6-week-old Japanese quail females which were kept under 8L:16D short-day conditions. However, no ovulation was induced in these birds. 2. Injection of 500 micrograms of the glycoprotein into other immature short-day females was performed following the above chronic administration, 12 or 14 and 15 d after implantation of the osmotic pump. About 24 h after injection, 3 of 14 females laid one or two eggs. Ovulation was confirmed in 4 females by autopsy. A total of 5 of 14 females ovulated 6 eggs, and significant development of the oviduct and the cloacal opening were observed in all of the treated females. 3. Thus, complete ovarian function could be induced in sexually immature female Japanese quail by administration of avian gonadotrophin using a combination of an osmotic pump and an injection.

Purification and characterization of chicken follicle-stimulating hormone

1. Highly purified chicken follicle-stimulating hormone (cFSH) was isolated from chicken pituitaries by differential extraction, sequential chromatography on HPLC cation and anion exchange columns, and gel filtration chromatography. 2. Purified cFSH (USDA-cFSH-K-1) had a potency of 77.44 units/mg in a chicken testes radioreceptor assay, and was biologically active in stimulating the secretion of progesterone by chicken granulosa cells. 3. Purified cFSH contained negligible luteinizing hormone and thyroid stimulating hormone activity. 4. The apparent molecular weight of cFSH was 38,000 Da and a single band on isoelectric focusing had a pI of 4.65.

Comparison of the fractionation and assay of domestic duck and fowl pituitary gonadotrophins

1. Pituitary glycoproteins from domestic ducks and fowls were fractionated to separate luteinising hormone (LH) and follicle stimulating hormone (FSH) activities using the same chromatographic steps. 2. Fractions were bioassayed for LH using the release of progesterone from fowl granulosa cells and for thyroid stimulating hormone (TSH) by measuring the release of thyroxine in 3-d-old chicks. Follicle stimulating hormone activity was measured either in a cockerel-testes radioreceptor assay or by the release of oestrogen from cultured rat Sertoli cells. 3. Fractions containing predominantly FSH or LH activity were isolated from the fowl glycoproteins. Duck gonadotrophin did not occur in fractions corresponding to those containing fowl FSH. 4. Duck gonadotrophin was found in a fraction corresponding with the most highly purified fowl LH fraction. A duck LH fraction was found with little FSH activity for which there was no corresponding fowl LH fraction. 5. It is concluded that domestic fowl and duck gonadotrophins have different chromatographic properties. Further study is required to determine whether the purified duck gonadotrophin preparation comprises proteins with similar physico-chemical properties but with separate FSH and LH biological activities.

Biological and binding activities of pituitary hormones from the ostrich, Struthio camelus

Biological and binding activities of adenohypophysial hormones purified from the ostrich (ost), Struthio camelus, were compared to those of the corresponding hormones derived from mammalian and other avian species. The potency of ostrich prolactin was comparable to those of other avian preparations and slightly less active than the ovine hormone when tested in the pigeon crop-sac assay, but ostrich growth hormone (GH) was more potent than several other avian preparations and was comparable to mammalian GH in the rat tibia bioassays. Marked discrepancies were evident in the activities of both ostrich gonadotropins (ostGn) when they were tested in a variety of in vivo and in vitro bioassays and radioreceptor assays (RRAs). Both the ostrich follicle-stimulating hormone (ostFSH) and luteinizing hormone (ostLH) were among the most potent tested thus far in in vivo bioassays for total gonadotropin in a lizard and a cockerel; a high sialic acid content may account for these high potencies. OstFSH was also the most potent nonmammalian Gn tested in two FSH specific mammalian bioassays, an in vivo (ovarian augmentation) and an in vitro (cAMP production) rat bioassay; in fact, ostFSH behaved more like a mammalian than an avian hormone in these assays. However, the binding activity of ostFSH was not unlike that of other avian FSH preparations when tested in either mammalian or nonmammalian FSH-RRA systems. OstLH was more potent than other avian preparations in an in vitro mammalian bioassay, but not in avian or amphibian LH bioassays; species specificity was pronounced among these LH assays. Binding activities of ostLH in mammalian and avian LH-RRAs were generally consistent with potencies in the two species of bioassays. However, a marked discrepancy was apparent in the behavior of ostLH in FSH-RRAs. Although ostLH had very low FSH activity when tested by radioimmunoassay, by bioassay, or by FSH-RRA with avian gonads, it was equipotent to ostFSH in competing for FSH-binding sites on the mammalian gonad; in this respect it was more like turkey than chicken LH. The ability of ostLH to antagonize the biological activities of ostFSH in the stimulation of cAMP by rat seminiferous tubules confirms that ostLH binds to the same functional receptors as FSH on the rat testis, even though it does not induce the characteristic physiological response associated with FSH.