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Induction of Lysozyme Gene Expression During Involution of Mouse Mammary Gland

  • Lee, M.J. (Department of Genetic Engineering, Biotechnology Research Institute, College of Agriculture Chonnam National University) ;
  • Han, O. (Department of Genetic Engineering, Biotechnology Research Institute, College of Agriculture Chonnam National University) ;
  • Back, K. (Department of Genetic Engineering, Biotechnology Research Institute, College of Agriculture Chonnam National University) ;
  • Choi, Y.J. (School of Agricultural Biotechnology, College of Agriculture, Seoul National University) ;
  • Baik, M.G. (Department of Genetic Engineering, Biotechnology Research Institute, College of Agriculture Chonnam National University)
  • Received : 2000.10.09
  • Accepted : 2000.12.11
  • Published : 2001.04.01

Abstract

To understand molecular mechanisms of mouse mammary gland involution, clones were isolated by differential screening of a cDNA library. Partial sequences of a clone showed 100% identity to cDNA sequences of mouse lysozyme P gene. Northern analysis was performed to examine expression levels of lysozyme mRNA in mammary gland at several physiological states. Expression of lysozyme gene was induced at involution day 5 compared with lactating stage. High levels of lysozyme mRNA were also detected at virgin tissues. Two types of separate genes, P and M lysozyme, have been known in mouse, and we found that both lysozyme P and M genes were expressed in mammary tissues by reverse transcriptase-polymerase chain reaction. The lysozyme enzyme activity determined by lysoplate assay was also higher in involuted mammary tissues compared with lactating tissues, showing a similar trend to its mRNA levels. Lysozyme is an antimicrobial protein and involved in host defense mechanism. The increase in lysozyme gene expression may help to prevent microbial infection during mammary gland involution at which stage the residual milk in the mammary gland provides good nutritional sources for microbial growth.

Keywords

Mouse;Lysozyme;Gene Expression;Mammary Gland;Involution

Acknowledgement

Supported by : Korea Research Foundation