XVI International Botanical Congess

Acyl carrier protein (ACP), an essential component of fatty acid synthase, was used as a marker for studying fatty acid biosynthesis in diatoms. Ultrastructure, subcellular localization of ACP, and location of acp were compared in the non-photosynthetic Nitzschia alba, and the photosynthetic Chaetoceros muelleri. Two copies of acp were localized in the C. muelleri genome, while N. alba had a much reduced chloroplast genome. The ACP encoding genes of C. muelleri were cloned and sequenced to determine whether the two copies are identical. Ultrastructural examination of chemically fixed and cryofixed N. alba revealed that the organism lacked a typical diatom chloroplast, but retained a leucoplast. Immunolocalization of ACP was used to determine if the leucoplast is the site of fatty acid biosynthesis in N. alba.