A TUBULAR MASTIGONEME‐RELATED PROTEIN, OCM1, ISOLATED FROM THE FLAGELLUM OF A CHROMOPHYTE ALGA,OCHROMONAS DANICA¹

Abstract

The phylogenetic group stramenopiles refers to the systematic groups that possess tripartite tubular hairs (stramenopiles) on their flagella. There have been a number of studies describing the fine structure of these mastigonemes and a few studies isolating the component proteins; however, these proteins and their gene sequences have not yet been identified. In the present study, we identified a mastigoneme protein (Ocm1) of the chrysophycean alga Ochromonas danica Pringsh. (UTEX LB1298). Its corresponding gene, Ocm1, was identified by using degenerate primers that correspond to the partial amino acid sequences of a protein (85 kDa) obtained from a mastigoneme‐rich fraction of isolated flagella. The polypeptide encoded by Ocm1 has four cysteine‐rich, epithelial growth factor (EGF)–like motifs, potentially involved in protein–protein interactions. It lacks obvious hydrophobic regions characteristic of transmembrane domains, suggesting that this polypeptide is not likely a protein for anchoring the mastigoneme. In addition, a polyclonal antibody against Ocm1 labeled the area where the tubular shafts of the mastigonemes are located, but not the basal portion or the terminal filaments.

Analysis of Light-Dependent Cell Morphology and an Accumulation Response in <i>Ochromonas danica</i>

“…Although both positive and negative phototaxis were observed in low and high intensity light, the responsiveness was generally lower than that of Euglena (Häder et al 1981). There have been some morphological studies on stramenopile algae, such as the comparison of the 2 different types of flagellar apparatus and mastigoneme-related proteins (Bouck 1971, Rosenbaum and Child 1967, Yamagishi et al 2007). However, there have been no morphological comparisons following irradiation under monochromatic light.…”

Biology, Diversity and Ecology of Free-Living Heterotrophic Flagellates

“…Flagellate cells of stramenopiles typically possess two heterodynamic heterokont fl agella inserted anteriorly to ventrally; a posteriorly directed mature fl agellum is smooth but an anteriorly directed immature fl agellum is ornamented by characteristic tripartite (base, shaft and terminal hairs) tubular hairs ( stramen = straw, pilus = hair). Recent studies have identifi ed a protein of the fl agellar hairs (Honda et al 2007 ;Yamagishi et al 2007 ). Because the tubular fl agellar hairs reverse the water current produced by normal fl agellar beats, preys are drawn to the cells from the anterior area in phagotrophic stramenopiles.…”

Flagellar Motions in Phototactic Steering in a Brown Algal Swarmer

“…Heterokont flagellates such as brown and chrysophycean algae have two heterogeneous flagella that are easily distinguishable in morphology as well as in motility (1). The anterior flagellum bears many tubular mastigonemes on its surface (2,3) and provides progressive force through undulatory beating (4). The smooth posterior flagellum is usually inactive but occasionally bends sideways.…”