|
Associate Director, Ottawa Hospital Research Institute
Senior Scientist
,
Chronic Disease
, Ottawa Hospital Research Institute
Professor, Departments of Obstetrics and Gynecology, and Cellular and Molecular Medicine and Associate Chair, Research, Department of Obstetrics and Gynecology, University of Ottawa
Biographical Sketch
Dr. Baltz received his B.A. in Physics from the University of Pennsylvania, a Ph.D. in Biophysics from The Johns Hopkins University, and postdoctoral training in Dr. John Biggers' laboratory at Harvard. Dr. Baltz is now Associate Director and a Senior Scientist at the Ottawa Hospital Research Institute, and Professor and Associate Chair of the Department of Obstetrics and Gynecology at the University of Ottawa, as well as being cross-appointed in the Department of Cellular and Molecular Medicine. Dr. Baltz has received an Ontario Premier's Research Excellence Award, a James Shannon Award from the US National Institutes of Health, and has been a Medical Council of Canada Scholar. He currently serves as Director of the Program on Oocyte Health, a Strategic Initiative of the Canadian Institutes of Health Research (CIHR) Institute of Human Development, Child and Youth Health. He is a specialist in the field of reproduction and developmental biology, where he has published extensively in the areas of preimplantation embryo development and egg development in the ovary.
Research Interests
My laboratory works on mammalian oocyte growth and maturation, fertilization, and early embryo development. At the time a new life begins, the egg and embryo change very rapidly, virtually becoming a completely different organism every few hours. We are particularly interested in the physiological changes that occur to accommodate the constantly changing nature of the egg and embryo and their implications for the health of the embryo and offspring. Much of our work is directed towards understanding the precisely choreographed activation and deactivation of the array of transporters and other physiological mechanisms needed to supply the constantly changing needs of the egg and embryo during these earliest stages of development, and towards understanding what can go wrong.
The overall goals of our research are:
1) to better understand the changing physiology of oocytes and embryos as they rapidly develop at the beginning of life,
and
2) to improve the health of babies and the treatment of infertility through research leading to the development of improved techniques for producing healthy oocytes and embryos.
One major area of interest in our research is the control of cell size in very early embryos and oocytes. Cells regulate their size by adjusting intracellular osmotic pressure, which is the pressure produced by dissolved substances. Small, neutral organic compounds ("organic osmolytes") are preferentially accumulated by some types of cells to provide the intracellular osmotic support, and a small set of organic osmolytes appear to be particularly critical for maintaining embryo health. Although early preimplantation mouse embryos use some of the same organic osmolytes identified in other cells, the early embryo lacks expression of the known mammalian organic osmolyte transporters that can transport these compounds. Instead, we have discovered that a glycine transporter called GLYT1 acts as an organic osmolyte transporter in embryos, a novel role for this transporter apparently unique to early embryo development. We are currently investigating how it is regulated and how it is turned on when the egg is ovulated. This work could not only reveal key features of early embryo physiology, but could have fundamental implications for our understanding of how cells regulate their size.
Another project in my laboratory, which is part of the Program on Oocyte Health (see below and www.ohri.ca/oocyte), involves determining how oocytes develop the capacity to live independently as they grow and become mature. In the ovary, oocytes are surrounded by support cells which carry out many normal housekeeping functions for the oocyte, but connections with these cells are lost as the oocyte matures and is ovulated. So, the oocyte must be able to function independently by this point in its development. We are now studying how the support cells supply the growing oocyte with amino acids, which it needs to make proteins and for other key functions, and how the oocyte develops its own array of amino acid transporters during maturation to permit it to become metabolically independent by the time of ovulation. This should help us understand what the oocyte requires for healthy development, and may lead to improvements in our ability to produce mature oocytes in vitro for infertility treatment.
A final, longstanding area of interest for us are acid-base balancing (pH regulating) mechanisms in the oocyte and early embryo. We are currently looking at how the oocyte develops the capacity to regulate its intracellular pH on its own as it grows in the ovary. Early in its development, we have found that the oocyte has little capacity to regulate its intracellular pH, and only fully develops this ability as it nears its final size. In early oocytes, ovarian cells connected to the oocyte perform this and other functions for the growing oocyte. Our research in this area is aimed at finding out how the oocyte depends on ovary cells to regulate its pH until it is ready to take on that task for itself.
Our laboratory is part of the Program on Oocyte Health, a $2.8M, 5-year Strategic Initiative Grant from CIHR's Institute of Human Development, Child and Youth Health (IHDCYH). Dr. Baltz is the Director of this Program, which includes 15 Principal Investigators from across Canada working on five collaborative projects aimed at improving the health of oocytes used in treating infertility. For more information, please see www.ohri.ca/oocyte.
Overall, my laboratory hopes to add significantly to our knowledge of the physiological processes important to mammalian eggs and embryos at the very beginning of life. We also believe that this type of research will lead to improvements in treatments for infertility.
Selected Honours and Awards
2005 - Ottawa Academic Health Sciences Leadership Program
2000 - Premier's Research Excellence Award from the Government of Ontario
1993 - MRC Scholarship Award, Medical Research Council, Canada
1992 - Shannon Award, National Institutes of Health, USA
Selected Affiliations
2006 - Member, Institutional Advisory Board, Canadian Institutes of Health Research, Institute of Human Development, Child and Youth Health
2004 - Board of Reviewing Editors, Biology of Reproduction
2003 - Director, Program on Oocyte Health
2002 - Associate Editor, Journal of Cellular Physiology
1998 - Associate Editor, Molecular Reproduction and Development
Current Funding
2006 - 2011: Novel organic osmolyte transport and cell volume regulation mechanisms in oocytes and preimplantation embryos (CIHR Operating Grant)
2005 - 2010: Transport-mediated processes in oocyte growth and maturation (CIHR Operating Grant)
2003 - 2008: Program on Oocyte Health (CIHR Strategic Initiative on Healthy Gametes and Great Embryos, Director, with 14 other principal applicants)
2002 - 2007: Regulation of sperm acrosome reaction (NSERC Group Grant with Dr. J Ngsee)
Most Recent Publications (provided by The Ottawa Hospital Library Database)
FitzHarris G;Baltz JM;, (2009 Oct), Regulation of intracellular pH during oocyte growth and maturation in mammals, Reproduction, Vol.138, Issue 4, 619-627 -> view abstract
Pelland AM;Corbett HE;Baltz JM;, (2009 Jul 15), Amino Acid Transport Mechanisms in Mouse Oocytes During Growth and Meiotic Maturation, Biol Reprod, Vol.81, Issue 6, 1041-1054 -> view abstract
Tartia AP;Rudraraju N;Richards T;Hammer MA;Talbot P;Baltz JM;, (2009 Jul), Cell volume regulation is initiated in mouse oocytes after ovulation, Development, Vol.136, Issue 13, 2247-2254 -> view abstract
Petrunewich MA;Trimarchi JR;Hanlan AK;Hammer MA;Baltz JM;, (2009 Feb), Second meiotic spindle integrity requires MEK/MAP kinase activity in mouse eggs, Journal of Reproduction & Development, Vol.55, Issue 1, 30-38 -> view abstract
Rudraraju N;Baltz JM;, (2009), Amino acid carryover in the subzonal space of mouse fertilized ova affects subsequent transport kinetics, Zygote, -> view abstract
Wang L;Wang ZB;Zhang X;FitzHarris G;Baltz JM;Sun QY;Liu XJ;, (2008 Jan 1), Brefeldin A disrupts asymmetric spindle positioning in mouse oocytes, Developmental Biology, Vol.313, Issue 1, 155-166 -> view abstract
Anas MK;Lee MB;Zhou C;Hammer MA;Slow S;Karmouch J;Liu XJ;Broer S;Lever M;Baltz JM;, (2008 Dec), SIT1 is a betaine/proline transporter that is activated in mouse eggs after fertilization and functions until the 2-cell stage, Development, Vol.135, Issue 24, 4123-4130 -> view abstract
Anas MK;Hammer MA;Lever M;Stanton JA;Baltz JM;, (2007 Jan), The organic osmolytes betaine and proline are transported by a shared system in early preimplantation mouse embryos, Journal of Cellular Physiology, Vol.210, Issue 1, 266-277 -> view abstract
FitzHarris G;Siyanov V;Baltz JM;, (2007), Granulosa cells regulate oocyte intracellular pH against acidosis in preantral follicles by multiple mechanisms, Development, Vol.134, Issue 23, 4283-4295 -> view abstract
Fitzharris G;Baltz JM;, (2006 Feb), Granulosa cells regulate intracellular pH of the murine growing oocyte via gap junctions: development of independent homeostasis during oocyte growth, Development , Vol.133, Issue 4, 591-599 -> view abstract
Note: This is not a complete list of publications. More publications may be available in The Ottawa Hospital Library database and Pubmed (search by last name and initials).
| |
Civic Campus
(see 
