The present invention provides isolated and recombinant avian nucleic acid molecules comprising at least one avian MAR and an avian nucleic acid sequence encoding an ovalbumin transcriptional regulatory region. The isolated nucleic acid of the present invention is useful for reducing chromosomal positional effects upon the transcription of a transgene operably linked to the ovalbumin transcriptional regulatory region and transfected into a recipient avian cell The recombinant nucleic cid molecules of the present invention may further comprise a polyadenylation signal sequence or an avian 3' domain, and optionally, an internal ribosome entry site for expression of an operably linked heterologous nucleic acid insert in a transfected avian cell.