The 5′‐promoter and coding region of the macrophage expressed lysozyme encoding‐gene do not reveal variants associated with high serum lytic activity in Polish Black‐and‐White cattle

Abstract

SummaryIn a previous study two bulls were identified in the Polish Black‐and‐White Lowland cattle population that inherited an increased serum lytic activity (LZM+) in a heterozygous fashion. The LZM+ phenotype shows in both half‐sib families a strong co‐segregation with a particular allele of the LysMic microsatellite localized within intron 2 of the immunorelevant macrophage expressed lysozyme encoding‐gene (mLYZ). No trait‐associated mLYZ promoter variant had previously been found. Here, we examine genetic polymorphisms within the entire coding region of this gene by comparative sequence analyses of all four exons in both bulls and two progenies exhibiting low serum lytic activity (LZM0). We found no mutations in the coding sequence of mLYZ gene. However, two single nucleotide polymorphisms were detected in introns 2 and 3 of this mLYZ gene at positions 8603 (C/T transition) and 9963 (C/A transversion). A polymerase chain reaction‐restriction fragment length polymorphism assay was developed to detect the C/T transition in intron 2, creating a polymorphic Sau3A restriction site. The ‘T’‐residue‐harbouring allele segregates with the LZM+ phenotype and is tightly linked to the previously reported diagnostic allele 7 of the LysMic microsatellite. Unaltered DNA sequences in both, promoter and coding region of mLYZ encoding gene in animals with high and low lytic activity indicates that this parameter is influenced by factors other than quantity or quality of the enzyme encoded by this gene.