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Posttranslationally modified tubulins and microtubule organization in hemocytes of the brine shrimp, Artemia franciscana
Author(s) -
Day Rossalyn,
Criel Godelieve R.J.,
Walling Marvlyn A.,
MacRae Thomas H.
Publication year - 2000
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/(sici)1097-4687(200006)244:3<153::aid-jmor1>3.0.co;2-t
Subject(s) - biology , microtubule , centriole , tubulin , microbiology and biotechnology , cytoplasm , cytoskeleton , centrosome , organelle , flagellum , motility , cell , biochemistry , gene , cell cycle
Abstract ABSTRACT Crustaceans possess blood cells (hemocytes) that mediate organismal defense and are analogous to vertebrate leukocytes. In order to more fully characterize these types of cells, hemocytes of the branchiopod crustacean, Artemia franciscana , were analyzed. The data indicate that Artemia have one type of hemocyte, ranging in morphology from compact and spherical to flat and spreading when examined in vitro. Electron microscopy revealed many cytoplasmic granules in the hemocytes and only a limited number of other membrane‐bound organelles. Centrioles and microtubules were also visible in thin sections of chemically fixed samples. The cytoplasm of spherical hemocytes was completely labeled by general antitubulin antibodies, but in flattened hemocytes packing of cytoskeletal elements was less tight and individual microtubules were observed. Probing of Western blots disclosed acetylated, tyrosinated, and detyrosinated tubulin isoforms in hemocyte homogenates, the first characterization of posttranslationally modified tubulins in this cell type. Acetylated tubulin was restricted to a subset of microtubules, whereas tyrosinated microtubules were displayed more abundantly. Staining obtained with antibody to detyrosinated tubulin was unusual because it was limited to the perinuclear region of hemocytes. Incubation of blood cells with a monoclonal antibody to γ‐tubulin yielded fluorescent dots sometimes in pairs, a pattern characteristic of centrosomes. The findings support the conclusion that Artemia hemocytes undergo rapid morphogenesis in vitro accompanied by extensive rearrangement of their microtubules, the latter probably indicative of cytoskeletal changes that occur during cell movement and phagocytosis. Additionally, the hemocytes contain posttranslationally modified α‐tubulins and centrosome‐associated γ‐tubulin, both with the potential to influence microtubule organization and function. J. Morphol. 244:153–166, 2000 © 2000 Wiley‐Liss, Inc.