Role of autophagy in porcine spermatogonia

Valenzuela-Leon, Paula

Role of autophagy in porcine spermatogonia

dc.contributor.advisor	Dobrinski, Ina
dc.contributor.author	Valenzuela-Leon, Paula
dc.contributor.committeemember	Cross, James C.
dc.contributor.committeemember	Van Der Hoorn, Frans A.
dc.contributor.committeemember	Wynne-Edwards, Katherine Elizabeth
dc.date	2018-11
dc.date.accessioned	2018-08-09T13:49:47Z
dc.date.available	2018-08-09T13:49:47Z
dc.date.issued	2018-08-07
dc.description.abstract	Spermatogonial stem cells (SSCs) sustain spermatogenesis through tightly controlled self renewal and differentiation processes. A long-term culture for porcine spermatogonia has not been established yet. To thrive in culture conditions, a cell requires to adapt to the environment. One of the tools that cells have developed to manage stress is autophagy. Autophagy is induced by cellular stress, which results in lysosomal degradation and recycling of the degradation product to generate energy for cellular homeostasis. Therefore, the main objective of this thesis is to elucidate the role autophagy plays in porcine germ cells. Initially, we identified that autophagy is active at basal levels in situ; upon isolation from the testis, the levels of autophagy increase significantly. Autophagic levels were then analyzed in testis tissue formed de novo. After 6 weeks, autophagic levels were at basal levels, which indicated that re-introduction to the microenvironment decreases germ cell stress. Considering that in vitro conditions upregulate autophagy, germ cells were cultured in two different media, and found that levels of autophagy are lower in nutrient rich medium. Levels of reactive oxygen species (ROS) were measured and were found to decrease germ cell viability; upon autophagy stimulation, viability increased. Conversely, upon autophagic inhibition, ROS increased, and germ cell viability decreased. These results suggested that autophagy is a cytoprotective mechanism for germ cells and can be used as an indicator for stress in vitro. To investigate the role of autophagy in germ cells in the presence of toxicants, we evaluated the levels of autophagy in primate testis tissue xenografted to mice exposed to phthalates. It was found that germ cells exposed to this toxicant had higher levels of autophagy than the controls. To evaluate the effects of toxicants in vitro, germ cells were treated with another phthalate, which caused germ cell viability to decrease. Upon autophagy induction, germ cell viability increased accordingly. These results show that autophagy is a cell protective mechanism for germ cells exposed to a toxicant. Overall, the work in this thesis identifies autophagy as an essential process for germ cell homeostasis.	en_US
dc.identifier.citation	Valenzuela-Leon, P. (2018). Role of autophagy in porcine spermatogonia (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32798	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/32798
dc.identifier.uri	http://hdl.handle.net/1880/107616
dc.language.iso	eng
dc.publisher.faculty	Graduate Studies
dc.publisher.faculty	Veterinary Medicine
dc.publisher.institution	University of Calgary	en
dc.publisher.place	Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	spermatogonial stem cells
dc.subject	autophagy
dc.subject	phthalates
dc.subject	germ cells
dc.subject	Testis
dc.subject.classification	Biology--Cell	en_US
dc.subject.classification	Veterinary Science	en_US
dc.title	Role of autophagy in porcine spermatogonia
dc.type	doctoral thesis
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.item.requestcopy	true