There are two objectives of the ongoing research in my lab. Our first goal is to understand the process of follicle selection and development in the hen. The features of avian follicle development make the hen an ideal model for understanding the process of regulation of follicular recruitment. It is possible to study the production of a specific hormone by an individual follicle. We have studied the ovarian hormones inhibin, activin and anti-mullerian hormone as well as the oocyte-specific factor, GDF9. By understanding the interaction of the somatic cells and the oocyte in a species in which preovulatory development is so ordered and predictable, it may be possible to generalize these findings to other domestic animal species as well. A fundamental understanding of follicular recruitment is essential to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Our second research goal relates to the development and characterization of the chicken as a model for human ovarian cancer. There is no animal model, other than the hen, which spontaneously develops ovarian cancer with a high incidence. Previous studies, as well as our own data, show that hens develop ovarian cancer with a striking similarity to that found in human females. The main cause of the lethality of ovarian cancer in women is the fact that it is usually diagnosed at an advanced stage. The availability of an animal model will increase the chance of finding a marker for early diagnosis. In addition, an animal model will permit the testing of pharmaceuticals that may decrease the growth of this cancer. Finally, selected genomic analysis of hens with and without the disease may reveal a difference that underlies differential susceptibility to ovarian cancer.
Lemcke, R. A., C.S. Stephens, K.A. Hildebrandt and P. A. Johnson. Anti-Müllerian hormone type II receptor in avian follicle development. Biology of Reproduction 99(6):1227-1234, 2018. https://doi.org/10.1093/biolre/ioy140
Stephens, Claire E. and P.A. Johnson. Occludin expression and regulation in small follicles of the layer and broiler breeder hen. General and Comparative Endocrinology, 248:106-113, 2017.
Hussein, M., V.V. Pillai, J.M. Goddard, et al., Sustainable production of housefly (Musca domestica) larvae as a protein-rich feed ingredient by utilizing cattle manure. PLOS One 2017; 12(2): e0171708. doi: 10.1371/journal.pone.0171708.
Stephens, Claire E. and P.A. Johnson. Bone Morphogenetic Protein 15 May Promote Follicle Selection in the Hen. General and Comparative Endocrinology 235:170-176, 2016.
Trevino, L. S. and P.A. Johnson. Estrogen Receptor Subtype Expression is Altered in the Hen Model of Ovarian Cancer. Journal of Molecular and Genetic Medicine 10:203, 2016. http://dx.doi.org/10.4172/1747-0862.1000203
Johnson, P.A., C. Stephens and J.R. Giles. The Domestic Chicken: Causes and Consequences of an Egg a Day. Poultry Science 94(4):816-820, 2015.