Osmolarity-Dependent Glycine Accumulation Indicates a Role for Glycine as an Organic Osmolyte in Early Preimplantation Mouse Embryos¹

^c Loeb Medical Research Institute, ^d Human IVF Laboratory, ^e Ottawa Civic Hospital, Departments of Obstetrics and Gynecology (Reproductive Biology Unit) and Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada K1Y 4E9

Mouse zygotes and early cleavage-stage embryos are sensitive to increased osmolarity. However, development can occur at higher osmolarities if any of a number of organic compounds are present. One of the most effective of these is glycine. We have found that the amount of glycine accumulated by embryos during in vitro culture from the zygote to two-cell stage depends on the osmolarity of the medium, with significantly more glycine accumulated at 310 or 340 mOsM than at 250 mOsM. The accumulated glycine is largely retained in a freely diffusible form, as it can be released via a swelling-activated pathway in two-cell embryos. Increased glycine accumulation does not seem to depend on an increase in its rate of transport. The transport rate is not higher in two-cell embryos that have been cultured from zygotes in hypertonic vs. normal medium, and hypertonicity only slightly stimulates transport in zygotes. Our results indicate that glycine functions as an organic osmolyte in early mouse embryos.

¹ Supported by Medical Research Council of Canada (MRC) Operating Grant MT12040. J.M.B. is an MRC Scholar.

² Correspondence: Jay M. Baltz, Loeb Medical Research Institute, 725 Parkdale Ave., Ottawa, ON, Canada K1Y 4E9. FAX: (613) 761–5327; jay{at}civich.ottawa.on.ca

This article has been cited by other articles:

				T. Hadi, M.-A. Hammer, C. Algire, T. Richards, and J. M. Baltz Similar Effects of Osmolarity, Glucose, and Phosphate on Cleavage past the 2-Cell Stage in Mouse Embryos from Outbred and F1 Hybrid Females Biol Reprod, January 1, 2005; 72(1): 179 - 187. [Abstract] [Full Text] [PDF]

				N. M Orsi and H. J Leese Ammonium exposure and pyruvate affect the amino acid metabolism of bovine blastocysts in vitro Reproduction, January 1, 2004; 127(1): 131 - 140. [Abstract] [Full Text] [PDF]

				C. L. Steeves, M.-A. Hammer, G. B. Walker, D. Rae, N. A. Stewart, and J. M. Baltz The glycine neurotransmitter transporter GLYT1 is an organic osmolyte transporter regulating cell volume in cleavage-stage embryos PNAS, November 25, 2003; 100(24): 13982 - 13987. [Abstract] [Full Text] [PDF]

				M. Sonoda, F. Okamoto, H. Kajiya, Y. Inoue, K. Honjo, Y. Sumii, T. Kawarabayashi, and K. Okabe Amino Acid-Permeable Anion Channels in Early Mouse Embryos and Their Possible Effects on Cleavage Biol Reprod, March 1, 2003; 68(3): 947 - 953. [Abstract] [Full Text] [PDF]

				M. Vallee, F. Guay, D. Beaudry, J. Matte, R. Blouin, J.-P. Laforest, M. Lessard, and M.-F. Palin Effects of Breed, Parity, and Folic Acid Supplement on the Expression of Folate Metabolism Genes in Endometrial and Embryonic Tissues from Sows in Early Pregnancy Biol Reprod, October 1, 2002; 67(4): 1259 - 1267. [Abstract] [Full Text] [PDF]

				F. D. Houghton1, J. A. Hawkhead, P. G. Humpherson, J. E. Hogg, A. H. Balen, A. J. Rutherford, and H. J. Leese Non-invasive amino acid turnover predicts human embryo developmental capacity Hum. Reprod., April 1, 2002; 17(4): 999 - 1005. [Abstract] [Full Text] [PDF]

				Y. G. Chung, M. R.W. Mann, M. S. Bartolomei, and K. E. Latham Nuclear-Cytoplasmic "Tug of War" During Cloning: Effects of Somatic Cell Nuclei on Culture Medium Preferences of Preimplantation Cloned Mouse Embryos Biol Reprod, April 1, 2002; 66(4): 1178 - 1184. [Abstract] [Full Text] [PDF]

				M. Kolajova, M.-A. Hammer, J. L. Collins, and J. M. Baltz Developmentally regulated cell cycle dependence of swelling-activated anion channel activity in the mouse embryo Development, September 15, 2001; 128(18): 3427 - 3434. [Abstract] [Full Text] [PDF]

				L. J. Van Winkle Amino Acid Transport Regulation and Early Embryo Development Biol Reprod, January 1, 2001; 64(1): 1 - 12. [Abstract] [Full Text]

				M.A. Hammer, M. Kolajova, M.-C. Leveille, P. Claman, and J.M. Baltz Glycine transport by single human and mouse embryos Hum. Reprod., February 1, 2000; 15(2): 419 - 426. [Abstract] [Full Text] [PDF]

				J. L. Collins and J. M. Baltz Estimates of Mouse Oviductal Fluid Tonicity Based on Osmotic Responses of Embryos Biol Reprod, May 1, 1999; 60(5): 1188 - 1193. [Abstract] [Full Text]

				M. Kolajova and J. M. Baltz Volume-Regulated Anion and Organic Osmolyte Channels in Mouse Zygotes Biol Reprod, April 1, 1999; 60(4): 964 - 972. [Abstract] [Full Text]