. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CELL BIOLOGY 207 A 80- j 70- I 60- | 50- 'P 40- § 30- 1 2°' 10- T T Sliding actin bundles field/min R 0 -- Js > fjt — ;yi K* 'j ] T Control 2mM 10 mM Ca' + Control 2 mM 10 mM Ca' + BAPTA BAPTA BAPTA BAPTA BAPTA BAPTA. Figure 1. (At The motile activities limning vesicles/field/min) in control extracts, extracts treated with 2 wM and III mM BAPTA, and extracts in the presence of I mM C The presence of actin filaments and bundles was verified by fluorescence microscopv Itop rim-1 fur control extracts and extracts treated wit
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CELL BIOLOGY 207 A 80- j 70- I 60- | 50- 'P 40- § 30- 1 2°' 10- T T Sliding actin bundles field/min R 0 -- Js > fjt — ;yi K* 'j ] T Control 2mM 10 mM Ca' + Control 2 mM 10 mM Ca' + BAPTA BAPTA BAPTA BAPTA BAPTA BAPTA. Figure 1. (At The motile activities limning vesicles/field/min) in control extracts, extracts treated with 2 wM and III mM BAPTA, and extracts in the presence of I mM C The presence of actin filaments and bundles was verified by fluorescence microscopv Itop rim-1 fur control extracts and extracts treated with two concentrations of BAPTA (2 mM and 10 mM). The same fields are shown bv AVEC-DIC microscopv I bottom row), photographed 3 min earlier than the corresponding fluorescence images. Actin bundles did not form in i v(/iK7s treated with 10 mM BAPTA, but the vesicles formed large clusters farrows in DIC micrograph). Extracts treated with I mM Co'* and 10 mM BAPTA were similar to extracts treated with If) mM BAPTA when viewed by fluorescence and AVEC-DIC microscopy (data not shown). cross-linking of actin filaments into bundles was inhibited (Fig. 1C; 10 mM), and sliding could not be observed (Fig. IB; 10 mM). These studies showed that, while myosin-II activity as measured by vesicle transport was stimulated by buffering free Ca2* with BAPTA. cross-linking of actin filaments was inhibited. Therefore, actin filaments assembled and served as tracks for vesicle move- ment, although the cross-linking of actin filaments into visible bundles was blocked by 10 mM BAPTA. In summary, when the calcium concentration in the extract was reduced by the addition of 10 mM BAPTA. myosin-Il-mediated vesicle transport increased Therefore the activation of MLCK by Ca2 * -CaM was not attenuated by the addition of this calcium chelator. However, actin filament bundling was inhibited, suggesting that actin filament bundling activity involves a calcium- sensitive step. The stimulation of mo
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
