SAES-422 Multistate Research Activity Accomplishments Report
Sections
Status: Approved
Basic Information
- Project No. and Title: NE1227 : Ovarian Influences on Reproductive Success in Ruminants
- Period Covered: 10/01/2012 to 09/01/2013
- Date of Report: 03/14/2014
- Annual Meeting Dates: 06/12/2013 to 06/14/2013
Participants
Bridges, Phillip pbrid2@email.uky.edu –University of Kentucky; Butler, Ron wrb2@cornell.edu –Cornell University; Dailey, Robert rdailey@wvu.edu –West Virginia University; Diaz, Francisco fjd10@psu.edu –Penn State University; Flores, Jorge jflores@wvu.edu –West Virginia University; Fortune, Joanne jf11@cornell.edu –Cornell University; Inskeep, Keith einskeep@wvu.edu –West Virginia University; Keating, Aileen akeating@iastate.edu –Iowa State; Memili, Erdogan em149@ads.msstate.edu –Mississippi State University; Ott, Troy tlo12@psu.edu –Penn State University; Pate, Joy jlp36@psu.edu –Penn State University; Rhoads, Shelly rhoadsm@vt.edu –Virginia Tech University; Thompson, Gary gat10@psu.edu –Penn State University; Townson, Dave dave.townson@unh.edu –University of New Hampshire; Tsang, Paul paul.tsang@unh.edu –University of New Hampshire; Wiltbank, Milo wiltbank@wisc.edu –University of Wisconsin; Wood, Jennifer jwood5@unl.edu –University of Nebraska; Yao, Jianbo jianbo.yao@mail.wvu.edu –West Virginia University
Accomplishments
- Identified alterations in the ovarian PI3K pathway due to heat stress (gilts), obesity (mouse), and toxin exposure (mice) which are linked to reduced fertility; also showed altered mRNA abundance in ovulated oocytes due to obesity
- Showed that endocrine disrupting chemicals (e.g. BPA, genistein) alter processes involved in establishing the primordial pool of follicles
- Developed assays to measure bovine inflammatory and oxidative stress factors in bovine follicular fluid
- Demonstrated the importance of zinc for meiotic maturation of the oocyte and establishment of proper imprints in the developing embryo.
- Demonstrated that LH regulates androgen production by fetal ovarian cortex and identified Bmp4 as an activator of primordial follicle growth
- Examined the regulation and function of KPNA7 in bovine oocytes and pre-implantation embryos.
- Showed a benefit of including PG600 with CIDR application on conception and pregnancy rates in ewes.
- Examined the use of artificial photoperiod to enhance breeding of fall-born ewe lambs
- Identified sperm proteins and small non-coding RNAs that contribute to embryo development success
- Linked increased intrafollicular androgen concentrations to altered theca cell gene expression and reduced fertility in the beef cow.
- Identified mRNAs in the oviduct that are regulated by estrogen and therefore may play an important role in fertilization and pre-implantation development
- Examined mechanisms by which CCN1 regulates vascular remodeling during folliculo-luteal transition including the role of integrins
- Determined that inhibition of Fas ligand-induced apoptosis of granulosa during follicular atresia by KRT8/18 filaments is not dependent on ERK1/2 or AKT signaling
- Identified a SNP in the growth hormone receptor associated with dairy cow fertility
- Demonstrated that PGF2a regulates intracellular calcium via the PLC-CAMKK2-AMPK pathways
- Demonstrated that supplementation of lactating dairy cows with methionine does not change morphological appearance of early embryos but alters gene expression in the embryos.
- Determined that increased insulin during the final stages of follicle growth can decrease ovulation rate of follicles and fertilization rate of oocytes.
- Evaluated the effects of increased length of proestrus period and estradiol on pregnancy loss.
- Demonstrated a novel mechanism for protein secretion by luteal cells which are responsible for stimulation of T cells.
- Demonstrated that pregnancy alters T cell populations in the corpus luteum which may be important for luteal rescue. Pregnancy also alters immune cell populations and inflammatory molecules in the endometrium which may promote placental growth and development
- Demonstrated that miRNA 34a regulates survival and function of luteal steroidogenic cells.
Impacts
- Defining factors that regulate primordial follicle formation, recruitment of follicles into the growing population, and inhibition of follicular atresia have implications on female reproductive longevity.
- Understanding how the follicular environment (e.g. androgens, zinc, obesity) impacts ovarian somatic cell function and oocyte maturation could improve oocyte quality and/or the selection of replacement animals with follicular environments conducive to good vs. poor oocyte quality.
- Paraoxonase1 is a negative acute phase protein produced by the liver that has anti-oxidant and anti-inflammatory activities. Research data in dairy cows shows that paraoxonase1 is transferred to ovarian follicular fluid from blood and may act to protect oocytes from local metabolic/oxidative damage and, thereby, may enhance fertility during breeding.
- Defining mechanisms regulating the folliculo-luteal transition will provide insight on normal luteal function as well as mechanisms associated with granulosa carcinomas.
- Basic studies continue to increase our understanding of calcium signaling and immune function impact on luteal steroidogenesis, survival, and/or regression which can be used to improve synchronization protocols and pregnancy rates in ruminants.
- Fertility in dairy cows may be compromised by high circulating insulin especially if this is combined with excessive LH during the final stages of follicle development.
- Improved methods for increasing estradiol near AI can reduce pregnancy losses.
- Knowledge of paternal impact on embryo development
- Evaluation of approaches to enhance out-of-season breeding has generated new knowledge and increased income for cooperating producers.