. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LlMl'WS AMEBOCYTE CYTOSKELETON ' • • 61 - •/- > ^ ":?. ."i' V v°v''" •«*^«I*-I >-• ?%&•• 1-i" 1^-. Figure 5. Structure of unactivated cells. TEM thin sections, (a) Longitudinal section overview, showing granules (gr). Golgi apparatus (ga). nucleus (n). mitochondria (m). Note: background material external to cell = fixed hemocyanin. (b. c) Enlarged views of gr-labeled granules in the same cell, showing the granules separated from the plasma membrane by a gap of —50 nm (arrowheads), (d) Marginal b
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. LlMl'WS AMEBOCYTE CYTOSKELETON ' • • 61 - •/- > ^ ":?. ."i' V v°v''" •«*^«I*-I >-• ?%&•• 1-i" 1^-. Figure 5. Structure of unactivated cells. TEM thin sections, (a) Longitudinal section overview, showing granules (gr). Golgi apparatus (ga). nucleus (n). mitochondria (m). Note: background material external to cell = fixed hemocyanin. (b. c) Enlarged views of gr-labeled granules in the same cell, showing the granules separated from the plasma membrane by a gap of —50 nm (arrowheads), (d) Marginal band (MB) of microtubules in cross section, with some of the interior microtubules indicated by arrows; like granules, the outermost MB microtu- bules of unactivated cells are separated from the plasma membrane by a gap of —50 nm. as indicated by the white lines (opposite arrowheads), (e) MB microtubules in longitudinal section, (f. g) Centriole pairs, shown in longitudinal and cross section, respectively, are a common feature. Longitudinal view shows typical closure at one end (f. arrow), and the triplet "pinwheel" directionality of pairs is evident in cross-sectional view (g. arrows). Bars: (a) = 1 /xm: (b, as in c) = /arm (d-g) = jum. bocytes prepared by freeze-substitution (Ornberg, 1985). or by a fixation method that preserves cortical F-actin in plate- lets (Boyles et «/., 1985; Tablin and Levin. 1988). Because of its binding specificity, phalloidin labeling verifies that an F-actin-rich cortical layer is present in the Limulux amebocyte (Fig. 4), as shown previously for F-actin in unactivated platelets and vertebrate thrombocytes (Debus el 1981: Lee et u/.. 2004). Thus, in the Linniliis ame- bocyte, the MB appears to act as a flexible frame llial maintains unactivated cell shape by pressing from \\ithin against an actin-rich, filamentous cortical network (Fig. l'i. in agreement with earlier proposals based on thin sections. Ple
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
