UNDERSTANDING HOW TO OPTIMIZE EMBRYONIC DEVELOPMENT IN CATTLE.

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: SPECIAL GRANT
• Reporting Frequency: Annual
• Accession No.: 0219542
• Grant No.: 2009-34135-20049
• Proposal No.: 2009-03285
• Project Start Date: Sep 1, 2009
• Project End Date: Aug 31, 2011
• Grant Year: 2009
• Program Code: [AH]- Tropical & Subtropical Research/T STAR

Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611

Performing Department
Animal Sciences

Non Technical Summary
Delayed or incomplete embryo development leads to pregnancy failure in cattle and most other food producing animals. The overall goal of this work is to gain insight into the critical regulatory events controlling early embryo development so that schemes can be developed to increase the reproductive efficiency and overall profitability of dairy and beef operations. We propose that embryo-derived fibroblast growth factors (FGF) are vital for pregnancy success in cattle. Experiments outlined in this proposal are aimed at clarifying the importance of one particular factor, termed FGF2, for establishing and maintaining pregnancy in cattle. This work will provide new fundamental knowledge of the key physiological, endocrine and molecular events associated with optimal embryo development in cattle. Knowledge gained form this work has the potential of being used to design management, biotechnology, or genetic-based strategies to reduce embryonic wastage during early pregnancy and thereby enhance overall reproductive efficiency in cattle.

Animal Health Component

20%

Research Effort Categories

Basic

80%

Applied

20%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
301	3410	1020	20%
301	3410	1030	40%
301	3410	1050	40%

Knowledge Area
301 - Reproductive Performance of Animals;

Subject Of Investigation
3410 - Dairy cattle, live animal;

Field Of Science
1030 - Cellular biology; 1020 - Physiology; 1050 - Developmental biology;

Keywords

fibroblast growth factor

interferon tau

trophectoderm

embryo development

pregnancy

Goals / Objectives
The long term goal of this research is to improve our basic understanding of bovine embryo development and provide new appreciations for mechanisms controlling embryo survival after transfer to surrogates. These new insights eventually could serve an important purpose for developing new strategies to mitigate heat stress-induced infertility in cattle. Work by this laboratory implicates several FGFs as regulators of gene expression in bovine embryos. One of these is FGF2. Its release from the uterine epithelium throughout the estrous cycle and early pregnancy make it available to embryos during early pregnancy. FGF2 also is produced by the early developing bovine embryo. This laboratory proposes that FGF2 is required to optimize blastocyst formation and subsequent embryo survival in cattle. Two specific aims will be examined in this work. In aim 1, research endeavors will assess whether FGF2 is required for blastocyst formation in bovine embryos. Work outlined in aim 2 will assess the merits of using an FGF2-based therapy to improve pregnancy outcome in lactating dairy cows.

Project Methods
Studies designed for this work will establish whether FGFs, and specifically FGF2, are required for normal bovine embryo development. In the first study, a chemical that inhibits tyrosine kinase activity in FGF receptors will be used to establish whether an assortment of FGFs interacting with various receptor subtypes is required for embryo development to blastocysts. A second study will be completed using antibodies that specifically block FGF2 from interacting with its receptor to determine if embryo-derived FGF2 is required for normal embryonic development in cattle. A third study will be completed to determine if FGF2 supplementation to bovine embryos during their development in vitro improves their subsequent survival after transfer to surrogates. Upon completion of these studies, it should become clear whether FGF2 or potentially another embryo-derived FGF is required for bovine blastocyst formation, expansion and hatching.

Progress 09/01/10 to 08/31/11

Outputs
OUTPUTS: This year's work has extended on initial findings and is examining new asppects of how FGFs mediate early embryo development in cattle. These outputs are being disseminated to other scientists by publishing findings and presenting findings at international conferences. PARTICIPANTS: Dr. Alan serves at PI. Dr. Peter Hansen serves as co-PI. Sarah Fields is working on this project as part of her PhD. Drs. Qi En Yang and Manabu Ozawa also worked on this project. Their publications are forthcoming. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
One key finding of this work is the discovery that FGFs influence several imporant aspects of embryo development after blastocyst formation (day 7 of pregnancy). Several new lines of research are being initiated based on the initial observations made in this work.

Publications

• Fields, S.D., Hansen, P.J. and Ealy, A.D. 2011. Fibroblast growth factor requirements for in vitro development of bovine embryos. Theriogenology 75:1466-1475.

Progress 09/01/09 to 08/31/11

Outputs
OUTPUTS: The original aims have been completed. Present research is examining new avenues of reserach that stemmed from this work. These outputs are being disseminated to other scientists by publishing findings and presenting findings at international conferences. PARTICIPANTS: Dr. Alan Ealy serves as PI for this project. Dr. Manabu Ozawa completed work on this project as part of his postdoctoral fellwship. Ms. Sarah Fields completed work on this project as part of her PhD program. Dr. Regina Esterman is working on this project as part of her duties as a laboratory technician. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
We are finding that FGF2 (and other FGFs) have several interesting impacts of embryo development after blastocyst formation. Currently we are focusing on understanding how FGF2 affect trophoblast adhesion. These and other research interests will improve our understanding of how paracrine factors impact embryo development and early placental development in cattle.

Publications

• No publications reported this period

Progress 09/01/09 to 08/31/10

Outputs
OUTPUTS: This year's work focused on completing work outlined in aim 1 (assess whether FGFs are required for blastocyst formation in bovine embryos). Work on this aim is nearly completed. Studies outlined in aim 2 are being initiated (assess the merits of using an FGF-based therapy to improve pregnancy outcome in lactating dairy cows). These outputs have been disseminated to other scientists by publishing findings and presenting findings at international conferences. PARTICIPANTS: Dr. Alan Ealy serves as PI on this project. Dr. Peter Hansen serves as co-PI. Sarah Fields is working on this project as part of her PhD prgram. Dr. Manabu Ozawa is working on this project as part of his postdoctoral fellowship. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
New knowledge about the potential functions of FGF2 and other FGFs has been realized with this work. Notably, FGF2 supplementation has little effect on early embryonic development but is important for several aspects of blastocyst formation and post-hatching development. The necessity of FGF2 and other FGFs in post-hatching development is being pursued in year 2 work.

Publications

• Rodina, T.M., Cooke, F.N., Hansen, P.J. and Ealy, A.D. 2009. Oxygen tension and medium type actions on blastocyst development and interferon-tau secretion in cattle. Anim Reprod Sci. 111:173-188.
• Fields, S.D., Hansen P.J., and Ealy AD. 2010. The importance of fibroblast growth factors on bovine embryo development in vitro. ADSA/ASAS Joint Annual Conference. Denver, CO. July 11-15, 2010.
• Ozawa,M. and Ealy, A.D. 2010. Expression profiling of fibroblast growth factor receptors and FGF4, and their roles during pre- and peri-implantation embryonic development in the bovine. Society for the Study of Reproduction 43rd Annual Meeting, Milwaukee, WI.