Multiple cDNA sequences of bovine tracheal lysozyme

Area of Science:

• Veterinary Science
• Molecular Biology
• Immunology

Background:

• Lysozyme prevents bacterial invasion at body surfaces.
• Serous gland cells in the respiratory tract are primary sources of lysozyme.
• The cow genome has multiple lysozyme-like genes, necessitating investigation into their expression.

Purpose of the Study:

• To identify which lysozyme-like genes are expressed in cow tracheal gland serous cells.
• To characterize the different lysozyme messenger RNA (mRNA) transcripts present in the cow trachea.
• To determine the major lysozyme form produced by these cells.

Main Methods:

• Screening of tracheal complementary DNA (cDNA) libraries using a probe from stomach lysozyme 2.
• Obtaining and sequencing three distinct lysozyme cDNAs: 5a, 7a, and 14d.
• Northern blot analysis to detect and differentiate lysozyme mRNA lengths.
• Polymerase chain reaction (PCR) amplification and hybridization assays on cultured serous cell RNA.

Main Results:

• Three novel lysozyme cDNAs (5a, 7a, 14d) were identified, with 5a and 14d being previously unreported.
• Northern blot revealed three distinct lysozyme mRNA lengths corresponding to cDNAs 5a, 7a, and 14d.
• Cultured serous cells predominantly expressed lysozyme mRNA corresponding to cDNA 5a.
• Lysozyme encoded by cDNA 5a is predicted to have a significantly higher arginine:lysine ratio than 7a and 14d lysozymes.

Conclusions:

• Multiple lysozyme mRNAs are expressed in the cow trachea.
• Lysozyme encoded by cDNA 5a is the major form expressed in tracheal gland serous cells.
• Structural differences in lysozymes may lead to varied functional properties, impacting bacterial defense in the respiratory tract.