The present disclosure generally relates to novel polynucleotide molecules for use in regulating gene expression in recombinant cells, such as labyrinthulomycetes cells. The disclosure further relates to nucleic acid constructs, such as vectors and expression cassettes, containing a regulatory element operably linked to a heterologous nucleotide sequence. The disclosure further relates to methods for stably transforming a host cell, such as a labyrinthulomycetes cell with transgenes. Stably transformed recombinant cells, progeny, biomaterials derived therefrom, and methods for preparing and using the same are also provided.