Progress 09/01/03 to 08/31/07
Outputs
In this project, our overall goal was to understand the role of anti-mullerian hormone (AMH) as it relates to follicle development in chickens, both laying and broiler breeder types. This is relevant to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Aim I was to characterize the expression (RNA and protein) and regulation of AMH with respect to follicle development in the ovary of laying hens. We performed Northern blot analyses and quantitative PCR on RNA extracted from the granulosa layers of various follicle sizes and determined that AMH is expressed most abundantly in the granulosa layer of small follicles. There are negligible amounts of AMH in follicles larger than 6 mm and the greatest amount was found in the small, growing follicles. Very small follicles (about 50 microns) were observed to be negative for AMH by immunohistochemistry (IHC). Oocyte-conditioned medium had an inhibitory effect
on the expression of AMH. The activity was heat-labile but could not be attributed to GDF9. Neither estradiol nor progesterone, at a variety of doses, affected expression of AMH from granulosa cells of different maturities. IHC verified that the granulosa layer is the primary source of AMH in the hen ovary. Testes were removed from 11-20 day old chick embryos, cultured and the media used as an enriched source of chicken AMH (testis-conditioned medium; TCM). Western blot showed one main band at approximately 70 kD. TCM significantly decreased FSH receptor expression in 3-5 mm granulosa cells with no significant effect in 6-8 mm granulosa cells. Proliferation was significantly enhanced from granulosa cells from both sized follicles. Aim II was to investigate the potential interaction between AMH and inhibin/activin. We found that activin A had no significant effect on AMH expression by granulosa cells, although activin A stimulated inhibin beta-B subunit as well as FSH receptor
expression. Activin was also effective in decreasing granulosa cell proliferation in granulosa cells from large follicles. Finally, in Aim III, we examined AMH expression in laying and broiler breeder hens and found that ovarian messenger RNA for AMH was significantly greater in broiler breeder hens as compared to laying hens. Furthermore, full-fed broilers had increased follicle development (with decreased egg production) and significantly greater AMH expression than restricted-fed hens. Increased expression of AMH was associated with increased disruption of the normal pattern of follicle development. Incubation of cultured granulosa cells with different doses of insulin, glucose and EGF had no direct effect on AMH mRNA expression.
Impacts
This research may have relevance to problems in commercially important birds such as broiler breeder hens and turkeys with relatively poor egg production.
Publications
- Johnson, PA, ME Urick, TR Kent and JR Giles. 2007. Expression and regulation of anti-mullerian hormone in the hen. BOR Papers in Press. Published on Sept 19, 2007 as DOI:10.1095/biolreprod.107.061879.
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Progress 09/01/05 to 08/31/06
Outputs
In this project, our overall goal is to understand the role of anti-mullerian hormone (AMH) as it relates to follicle development in chickens, both laying and broiler breeder types. This is relevant to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Aim I is to characterize the expression (RNA and protein) and regulation of AMH with respect to follicle development in the ovary of laying hens. We have performed Northern blot analyses and quantitative PCR on RNA extracted from the granulosa layers of various follicle sizes and determined that AMH is expressed most abundantly in the granulosa layer of small follicles. There are negligible amounts of AMH in follicles larger than 6 mm and the greatest amount is in follicles less than or equal to 1 mm. Oocyte-conditioned medium has an inhibitory effect on the expression of AMH. The activity is heat-labile but is not attributed to GDF9. Estradiol and
progesterone, at a variety of doses, did not affect expression of AMH from granulosa cells of different maturities. In contrast, testosterone, in a dose-dependent manner, inhibited AMH expression. Immunohistochemistry verified that the granulosa is the primary source of AMH in the hen ovary. In Aim II, we found that activin A had no significant effect on AMH expression by granulosa cells, although activin A stimulated inhibin beta-B subunit as well as FSH receptor expression. Finally, in Aim III, we have examined AMH expression in broiler breeder hens and found that ovarian RNA expression is significantly greater than that of laying hens. Furthermore, full-fed broilers had increased follicle development and significantly greater AMH expression than restricted-fed hens. Incubation of cultured granulosa cells with different doses of insulin and glucose had no direct effect on AMH mRNA expression.
Impacts
It may be possible to select hens with lower circulating levels of AMH and thereby select broiler breeder hens less prone to excessive follicle development. This may permit targeted selection which would not be to the detriment of the desirable traits such as fast growth and size.
Publications
- Johnson, P.A., Woodcock, J.R. and Kent, T.R. 2006. Effect of activin A and inhibin A on expression of the inhibin/activin Beta-B-subunit and gonadotropin receptors in granulosa cells of the hen. Gen Comp Endocrinol. 147:102-107.
- Johnson, P.A., Dickens, M.J., Kent, T.R. and Giles, J.R. 2006. Expression of anti-mullerian hormone is regulated by feeding level. Biol Reprod Supplement:171.
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Progress 01/01/05 to 12/31/05
Outputs
In this project, our overall goal is to understand the role of anti-mullerian hormone (AMH) as it relates to follicle development in chickens, both laying and broiler breeder types. This is relevant to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Aim I is to characterize the expression (RNA and protein) and regulation of AMH with respect to follicle development in the ovary of laying hens. We have performed Northern blot analyses and quantitative PCR on RNA extracted from the granulosa layers of various follicle sizes and determined that AMH is expressed most abundantly in the granulosa layer of small follicles. There are negligible amounts of AMH in follicles larger than 6 mm and the greatest amount is in follicles less than or equal to 1 mm. Oocyte-conditioned medium has an inhibitory effect on the expression of AMH. The activity is heat-labile but is not attributed to GDF9. Estradiol, at a
variety of doses, did not affect expression of AMH from granulosa cells of different maturities. Immunohistochemistry verified that the granulosa is the primary source of AMH in the hen ovary. In Aim II, we found that activin A had no significant effect on AMH expression by granulosa cells, although activin A stimulated inhibin beta-B subunit as well as FSH receptor expression. Finally, in Aim III, we have examined AMH expression in broiler breeder hens and found that ovarian RNA expression is significantly greater than that of laying hens. Furthermore, full-fed broilers had increased follicle development and significantly greater AMH expression than restricted-fed hens.
Impacts
It is anticipated that a particular gene or hormone that is altered by feeding regimen will be characterized and its role in excessive follicle growth defined. For example, it may be possible to select hens with lower circulating levels of AMH and thereby select broiler breeder hens less prone to excessive follicle development. This may permit targeted selection which would not be to the detriment of the desirable traits such as fast growth and size.
Publications
- Johnson, P.A. , M.J. Dickens, T.R. Kent and J.R. Giles. 2005. Growth differentiation factor 9: An oocyte factor regulating ovarian follicle development. In Functional Avian Endocrinology. Edited by A. Dawson and P. J. Sharp. Narosa Publishing House.
- Correa, S.M., E. Adkins-Regan and P.A. Johnson. 2005. High progesterone during avian meiosis biases sex ratios toward females. Biology Letters, 1(2):215-218.
- Johnson, P.A., M.J. Dickens, T.R. Kent and J.R. Giles. 2005. Expression and Function of Growth Differentiation Factor-9 in an Oviparous Species, Gallus domesticus. Biol Reprod 72:1095-1100.
- Sweeney, S. A. and P. A. Johnson. 2005. Messenger RNA and Protein Expression Analysis of Betaglycan in the Reproductive Tissues of the Domestic Hen. Biol. Reprod. 72:172-178.
- Johnson, P.A., C.F. Brooks and A.J. Davis. 2005. Pattern of secretion of immunoreactive inhibin/activin subunits by avian granulosa cells. Gen Comp Endocrinol. 142(3):233-239.
- Johnson, P.A., T.R. Kent and J.R. Giles. 2005. Expression and regulation of mullerian inhibiting substance in the ovary of the hen. Biol. Reprod. 72S:185.
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Progress 01/01/04 to 12/31/04
Outputs
In this project, our overall goal is to understand the role of mullerian inhibiting substance (MIS) as it relates to follicle development in chickens, both laying and broiler breeder types. This is relevant to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Aim I is to characterize the expression (RNA and protein) and regulation of MIS with respect to follicle development in the ovary of laying hens. We have performed Northern blot analyses and quantitative PCR on RNA extracted from the granulosa layers of various follicle sizes and determined that MIS is expressed most abundantly in the granulosa layer of small follicles. There are negligible amounts of MIS in follicles larger than 6 mm and the greatest amount is in follicles less than or equal to 1 mm. Oocyte-conditioned medium has an inhibitory effect although estradiol has a minimal effect on the expression of MIS. In Aim II, we plan
to evaluate the interaction between MIS and the inhibin/activin subunits. Finally, in Aim III, we have examined MIS expression in broiler breeder hens and found that RNA expression is comparable with that of laying hens except that expression is higher in the very small follicles less than or equal to 1 mm in broiler breeder hens.
Impacts
This research may have relevance to problems in commercially important birds such as broiler breeder hens and turkeys with relatively poor egg production.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
In this recently approved project, our overall goal is to understand the role of mullerian inhibiting substance (MIS) as it relates to follicle development in chickens, both laying and broiler breeder types. This is relevant to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Aim I is to characterize the expression (RNA and protein) and regulation of MIS with respect to follicle development in the ovary of laying hens. We have performed Northern blot analyses on RNA extracted from the granulosa layers of various follicle sizes and determined that MIS is expressed most abundantly in the granulosa layer of small follicles. In Aim II, we plan to evaluate the interaction between MIS and the inhibin/activin subunits. Finally, in Aim III, we will examine early follicle development in broiler breeder hens with respect to MIS expression. We will also determine whether follicle reserve and/or recruitment in
broiler breeders is altered by restricted feeding.
Impacts
This research may have relevance to problems in commercially important birds such as broiler breeder hens and turkeys with relatively poor egg production.
Publications
- No publications reported this period
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