Spermatozoa from a marsupial, the brushtail possum, contain β1,4-galactosyltransferase
A. G. Braundmeier A C , William G. Breed B and D. J. Miller A DA Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
B Discipline of Anatomical Sciences, University of Adelaide, SA 5005, Australia.
C Present address: Department of Obstetrics and Gynecology, University of Illinois at Chicago, Chicago, IL 60612, USA.
D Corresponding author. Email: djmille@uiuc.edu
Reproduction, Fertility and Development 20(3) 402-407 https://doi.org/10.1071/RD07128
Submitted: 7 August 2007 Accepted: 20 December 2007 Published: 11 March 2008
Abstract
β1,4-Galactosyltransferase-I (GalTase-I) is one of the key molecules on the sperm surface of eutherian mammals that is likely to be involved in binding to the egg coat, the zona pellucida, to mediate sperm–egg interaction. In laboratory mice, the species for which most data are available, this protein functions as a receptor for the zona pellucida protein ZP3 of the oocyte and, upon binding, triggers the sperm acrosome reaction. In the present study, we investigated the presence and abundance of GalTase-I in epididymal sperm extracts of a marsupial, the brushtail possum, Trichosurus vulpecula. For this, spermatozoa were collected from cauda epididymides and the amount of β1,4-galactosyltransferase activity in washed sperm extracts was compared with that of porcine spermatozoa. Overall β1,4-galactosyltransferase enzyme activity was found to be more abundant in possum sperm extracts than those from porcine spermatozoa (P < 0.05). Immunoblots with an antibody to mouse GalTase-I revealed that the molecular weight of possum spermatozoa GalTase-I was 66 kDa, which is similar to the molecular weight of GalTase-I in spermatozoa from eutherian mammals. The molecular weight of GalTase-I was the same in sperm extracts collected from the caput and cauda epididymides. These results demonstrate that GalTase-I is indeed present in possum spermatozoa and thus it may be a gamete receptor molecule on the sperm surface of marsupials as well as those of eutherian mammals.
Acknowledgements
The authors thank PIC North America (Hendersonvillle, TN, USA) and R. Wischover at the University of Illinois Swine Research Center for collecting boar semen and Chris Leigh of the Discipline of Anatomical Sciences, University of Adelaide for technical assistance. This material is based on work supported by the Illinois Council for Food and Agriculture Research, the University of Illinois Agricultural Experiment Station as part of Hatch Project ILLU-35-0335, and the United States Department of Agriculture National Research Initiative (99-35203). Any opinions, findings and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the Illinois Council for Food and Agriculture Research, the University of Illinois or the United States Department of Agriculture.
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