Generation of biologically active retro-genes upon interaction of mouse spermatozoa with exogenous DNA

Carmine Pittoggi, Rosanna Beraldi, Ilaria Sciamanna, Laura Barberi, Roberto Giordano, Anna Rosa Magnano, Liliana Torosantucci, Edoardo Pescarmona, Corrado Spadafora

Research output: Contribution to journalArticlepeer-review


Mature spermatozoa of most animal species can spontaneously take up foreign DNA molecules which can be delivered to embryos upon fertilization. Following this procedure, transgenic animals of various species have been generated. We recently discovered a reverse transcriptase (RT) activity in mouse spermatozoa that can reverse-transcribe exogenous RNA molecules into cDNA copies. These cDNA copies are transferred to embryos at fertilization, mosaic propagated as non-integrated structures in tissues of founder individuals and further transmitted to F1 progeny. Reverse-transcribed sequences behave as functional genes, being correctly expressed in tissues of F0 and F1 animals. To learn more about this mechanism and further characterize the reverse transcription step, we have now incubated spermatozoa with a plasmid harboring a green fluorescent protein (EGFP) retrotransposition cassette interrupted by an intron in the opposite orientation to the EGFP gene. We found that reverse-transcribed spliced EGFP DNA sequences are generated in sperm cells and transmitted to embryos in IVF assays. After implantation in foster mothers, embryos developed into mice that expressed EGFP in the blood vessel endothelia of a variety of organs. The EGFP-encoding cDNA sequences were detected in positive tissues as extrachromosomal mosaic-propagated structures, maintained in low-copy number (

Original languageEnglish
Pages (from-to)1239-1246
Number of pages8
JournalMolecular Reproduction and Development
Issue number10
Publication statusPublished - Oct 2006


  • Extrachromosomal structures
  • Reverse transcriptase
  • Sperm cells
  • Sperm-mediated gene transfer (SMGT)
  • Transgenic mice

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology


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