- B.A., Biochemistry, University of Kansas
- (Year Abroad) Physiology and Biochemistry of Farm Animals, University of Reading, England
- M.S., Animal Science, Purdue University
- Ph.D., Animal Science, Purdue University
The long-term focus in our laboratory is mammalian fertilization and the molecules involved in the fertilization process. Research is centered on interactions between sperm and oocyte plasma membrane molecules after sperm have undergone the acrosome reaction since our earlier work demonstrated that this was frequently the limiting step in vivo in subfertile animals. Details of these interactions including receptor/ligand pairings are still largely unknown. Environmental stresses such as elevated ambient temperature affect both the sperm’s ability and the oocyte’s ability to interact with each other at the plasma membrane level. We hypothesize that this is due to decreased/defective synthesis of interacting molecules. Our research typically involves in vitro fertilization or aspects of those procedures such as sperm penetration of zona-free oocytes as bioassays to support molecular studies evaluating individual molecules. Occasionally, research includes artificial or natural insemination to assess differences in in vivo fertility among males or females or to assess other parameters of reproduction in conjunction with sperm-oocyte interaction.
The pig is one of the primary species studied due in part to the availability of large numbers of gametes and hence molecules derived from gametes. Studies occasionally use other domestic species and gametes from exotic species as conservation of gamete receptors/ligands is of particular interest as well. Environmental toxicant-induced changes in the gamete receptors/ligands during rat gametogenesis and maturation was a previous model for our laboratory and also provided the opportunity to manipulate the system.
A second focus in our laboratory is the prepuberal regulation of Sertoli cell proliferation. Sertoli cell numbers are a major determinant of postpuberal testis size and sperm production. The number of Sertoli cells is generally believed to be determined prepuberally. In collaborative research, we have found that reducing endogenous estrogen in the boars postnatally leads to increased proliferation of Sertoli cells and larger postpuberal testes. In the pig, this can be accomplished independent of altered pituitary hormones. This strongly suggests a locally mediated mechanism.
- Integrated Animal Biology II (ABG 200B)
- Physiology of Reproduction (NPB 121/121L)
- Mammalian Gametogenesis and Fertilization (PGG 222)
Current Graduate Students
- Tana Almand, M.S. Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2019.
- Beth Graham, Ph.D. Program, Animal Biology Graduate Group. Expected Graduation Date: Summer 2017.
- Jennifer Jankovitz, M.S. Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2019.
- Kimberley Miller, M.S. Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2018.
- Javier Morales, Ph.D. Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2020.
- Simin Tang, M.S. Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2018.
- Kelly Zacanti, Ph.D. Program, Animal Biology Graduate Group. Expected Graduation Date: Spring 2020.
Former Graduate Students
- Carl Ducummon, Ph.D.
- Kim Katleba-Billock, Ph.D.
- Valerie Guerrero, M.S.
- Jennifer Hughes, Ph.D.
- Eddy Kao
- Lisa Kentfield
- Francesca LaPiana, M.S.
- Ann M. Leed, M.S.
- Erin Legacki, Ph.D.
- Megan J McCarthy, M.S.
- Puneet (Penny) Sidhu, M.S.
- Summer White, M.S.
- Katherine "Lily" Wu, Ph.D.
At-Taras EE, Berger T, McCarthy MJ, Conley AJ, Nitta-Oda BJ, Roser JF. Reducing estrogen synthesis in developing boars increases testis size and total sperm production. J Androl 2006; 27: 552-559.
Berger T, McCarthy M, Pearl CA, At-Taras E, Roser JF, Conley A. Reducing endogenous estrogens during the neonatal and juvenile periods affects reproductive tract development and sperm production in postpuberal boars. Anim Reprod Sci 2007.
Kao E, Villalon R, Ribeiro S, Berger T. Role for endogenous estrogen in prepubertal Sertoli cell maturation. Anim Reprod Sci 2012; 135:106-112.
Berger T, Kentfield L, Roser JF, Conley A. Stimulation of Sertoli cell proliferation: defining the response interval to an inhibitor of estrogen synthesis in the boar. Reproduction 2012; 143: 523-529.
Conley AJ, Corbin CJ, Thomas JL, Gee NA, Lasley BL, Moeller BC, Stanley SD, Berger T. Costs and consequences of cellular compartmentalization and substrate competition among human enzymes involved in androgen and estrogen synthesis. Biology of Reproduction 2012; 86: (1) 1-8.
Conley AJ, Orr VN, Trainor BC, Berger T, Hughes A. Multiple Forms of Aromatase in Suiformes: tissue distribution, regulation and functional significance, Jacques Balthazart and Greg Bell, (ed), Aromatase, estrogens and behavior 2012.
Berger T, Conley AJ, Van Klompenberg M, Roser JF, Hovey RC. Increased testicular Sertoli cell population induced by an estrogen receptor antagonist. Molecular and Cellular Endocrinology 2013; 366: 53-58.
Zamaratskaia G, Berger T. Skatole metabolism in the pigs with reduced testicular oestrogen synthesis. Reproduction in Domestic Animals 2014; 49(2): 302-305.
Berger T, Conley AJ. Reduced endogenous estrogen and hemicastration interact synergistically to increase porcine Sertoli cell proliferation. Biology of Reproduction 2014.
Berger T, Conley AJ. Reducing endogenous estrogen during prepuberal life does not affect boar libido or sperm fertilizing potential. Theriogenology 2014, 82: 627-35.
Kongmanas K, Kruevaisayawan H, Saewu A, Sugeng C, Fernandes J, Souda P, Angel JB, Faull KF, Aitken RJ, Whitelegge J, Hardy D, Berger T, Baker MA, Tanphaichitr N. Proteomic Characterization of Pig Sperm Anterior Head Plasma Membrane Reveals Roles of Acrosomal Proteins in ZP3 Binding. J Cell Physiol 2014; 230: 449-463.
Legacki E, Conley AJ, Nitta-Oda BJ, Berger T. Porcine Sertoli Cell Proliferation after Androgen Receptor Inactivation. Biology of Reproduction 2015; 92:93.
Katleba K, Legacki EL, Conley AJ, Berger T. Steroid regulation of early postnatal development in the corpus epididymidis of pigs. Journal of Endocrinology 2015; http://dx.doi.org/10.1530/JOE-15-0001.
Tanphaichitr N, Kongmanas K, Kruevaisayawan H, Saewu A, Sugeng C, Fernandes J, Souda P, Angel JB, Faull KF, Aitken RJ, Whitelegge J, Hardy D, Berger T, Baker M. Remodeling of the plasma membrane in preparation for sperm-egg recognition: roles of acrosomal proteins. Asian Journal of Andrology 2015; 17(4): 1-9.
Hughes JR, Berger T. Development of apical blebbing in the boar epididymis. PLOS One 2015; 10(5):e0126848, 2015.
Legacki EL, Scholtz EL, Ball BA, Stanley SD, Berger T, Conley, AJ. The dynamic steroid landscape of equine pregnancy mapped by mass spectrometry. Reproduction 2016;151:421-30
Hughes JR, Berger T. Regulation of apical blebbing in the porcine epididymis. J Anat. 2018; 232:515-522.
Berger T, Nitta-Oda BJ. 2018. Increased testicular estradiol during the neonatal interval reduces Sertoli cell numbers. Anim Reprod Sci. 189:146-151.