Different transmission rates of herpesvirus thymidine kinase reporter transgenes from founder male parents and male parents of subsequent generations

Authors

  • Aaron R. Ellison,

    1. Centre for Genome Research, University of Edinburgh, Edinburgh, United Kingdom
    2. Department of Biological Sciences, UMBC, Baltimore, Maryland
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  • Helen Wallace,

    1. Centre for Genome Research, University of Edinburgh, Edinburgh, United Kingdom
    Current affiliation:
    1. BBSRC Roslin Institute, Roslin, Midlothian, EH25 2PS, UK
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  • Raya Al-Shawi,

    1. Centre for Genome Research, University of Edinburgh, Edinburgh, United Kingdom
    Current affiliation:
    1. Department of Anatomy and Developmental Biology, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, UK
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  • Dr. John O. Bishop

    Corresponding author
    1. Centre for Genome Research, University of Edinburgh, Edinburgh, United Kingdom
    2. Department of Biological Sciences, UMBC, Baltimore, Maryland
    • CGR, University of Edinburgh, Edinburgh EH9 3JQ, UK
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Abstract

Previously we demonstrated that lines of transgenic mice carrying the herpes simplex type 1 virus thymidine kinase (HSV1-tk) reporter gene are malesterile. Ectopic transcription of the HSV1-tk reporter in the testis was initiated downstream of the normal translation initiation codon and truncated proteins consistent with translational initiation at the second and third ATG codons were synthesized. Here we describe the effects on fertility (1) of converting the second and third ATG codons of the HSV1-tk reporter to CTG codons and (2) of utilizing the HSV type 2 thymidine kinase (HSV2-tk) reporter gene, in which the second ATG codon is located downstream of the ATP-binding pocket of the enzyme. Both reporters were coupled to the bovine thyroglobulin promoter (bTG-tk1α and bTG-tk2 transgenes). The level of ectopic expression of these transgenes in the testis, relative to expression in the thyroid, was one to two orders of magnitude less than that of bTG-tk1.

Sixty percent of male founders carrying the bTG-tk1α and bTG-tk2 transgenes were fertile but did not transmit the transgene. In contrast, most males from subsequent generations were fertile and transmitted the transgenes at the expected frequency. This difference between founder males and male descendants is also observed with certain constructs in which the HSV1-tk reporter is coupled to other promoters. We attribute the effect to mosaicism among male founders, leading to competition between transgenic and nontransgenic spermatozoa and/or spermatogenic precursor cells and resulting in a lack of fertilization by transgenic sperm that would successfully fertilize eggs in the absence of competition. © 1995 Wiley-Liss, Inc.

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