. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. M1CROTUBULE ASSEMBLY IN SPlSL'Ll EXTRACTS 203 12 15 18 21. B 36 9 12 15 18 21 ia 100 90- 80- 70- 60 50 40 30- 20 10 0 6 9 12 15 18 TIME (MINUTES) 21 Figure 3. Quantitation of" IPT during the first meiotic cell cycle in extracts of oocytes ofSpisula. Particulate tubulin fractions were isolated from equal volumes of oocytes at 3' intervals following parthenogenetic activation. An equal volume of each paniculate tubulin traction was separated by SDS-PAGE and stained with Coomassie blue (A). Identical samples were blotted t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. M1CROTUBULE ASSEMBLY IN SPlSL'Ll EXTRACTS 203 12 15 18 21. B 36 9 12 15 18 21 ia 100 90- 80- 70- 60 50 40 30- 20 10 0 6 9 12 15 18 TIME (MINUTES) 21 Figure 3. Quantitation of" IPT during the first meiotic cell cycle in extracts of oocytes ofSpisula. Particulate tubulin fractions were isolated from equal volumes of oocytes at 3' intervals following parthenogenetic activation. An equal volume of each paniculate tubulin traction was separated by SDS-PAGE and stained with Coomassie blue (A). Identical samples were blotted to nitrocellulose and probed with a monoclonal antibody against u-tubulin (B). The blots were scanned with an Apple OneScanner interfaced to an Apple Ilex computer and analyzed with the public domain software program IMAGE. The amount of sedi- mentable tubulin obtained at each interval is expressed as a percent of the total interphase paniculate tubulin (IPT) detected in the oocyte (C). were recorded on TMAX 100 and 400 film developed in TMAX developer. For electron microscopy, samples were negatively stained with uranyl acetate on glow discharged, carbon-coated formvar grids. Results Inicrphasc purlieu/me nilndin (IPT) ami l/ic luhulin- contaiiung structure (TCS) A significant fraction (>10%) of the total detectable tubulin in surf clam oocytes sediments at very low cen- trifugal forces (Fig. 1). This tubulin corresponds to the interphase paniculate tubulin (IPT) described by Weisen- berg (1972). Following oocyte activation, the level of par- ticulate tubulin decreases steadily during the time course of nuclear envelop breakdown and formation of the first meiotic spindle (Figs. 2, 3). The decrease in sedimentable tubulin following parthenogenesis suggests that the inter- phase particulate tubulin (IPT) may be a storage form of tubulin that becomes solubilized. Tubulin dimers (Mr 100,000) alone or single micro- tubules cannot pellet at 2500g's. There are, however, large 15 /u
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
