XMAP230 is required for the organization of cortical microtubules and patterning of the dorsoventral axis in fertilized Xenopus eggs

Authors
Citation
Bj. Cha et Dl. Gard, XMAP230 is required for the organization of cortical microtubules and patterning of the dorsoventral axis in fertilized Xenopus eggs, DEVELOP BIO, 205(2), 1999, pp. 275-286
Citations number
50
Categorie Soggetti
Cell & Developmental Biology
Journal title
DEVELOPMENTAL BIOLOGY
ISSN journal
00121606 → ACNP
Volume
205
Issue
2
Year of publication
1999
Pages
275 - 286
Database
ISI
SICI code
0012-1606(19990115)205:2<275:XIRFTO>2.0.ZU;2-4
Abstract
The dorsoventral axis of Xenopus embryos is specified by a rotation of the egg cortex relative to the underlying yolky cytoplasm. This cortical rotati on, which occurs during the first cell cycle after fertilization, is depend ent upon an array of parallel microtubules in the subcortical cytoplasm. We have used confocal immunofluorescent microscopy and microinjection of affi nity-purified anti-XMAP230 antibody to address the role of XMAP230, one of three high-molecular-weight microtubule-associated proteins (MAPs) in Xenop us eggs, in the assembly and organization of the cortical microtubule array and specification of the dorsoventral axis. Confocal immunofluorescence mi croscopy revealed that XMAP230 was associated with cortical microtubules sh ortly after their appearance in the subcortical cytoplasm. XMAP230 staining became more prominent as microtubules were aligned and bundled during the cortical rotation. Loss of XMAP230 appeared to precede disassembly of corti cal microtubules at the end of the first cell cycle. Deeper within the cyto plasm, XMAP230 was associated with microtubules early in the assembly of th e sperm aster. However, later in the first cell cycle, XMAP230 was associat ed with microtubules (MTs) of the first mitotic spindle, spindle asters, an d the cortical MTs, but not with microtubule remnants of the sperm aster. M icroinjection of anti-XMAP230 antibody locally disrupted the assembly and o rganization of microtubules in the cortex of activated or fertilized eggs a nd resulted in defects in the dorsoventral patterning of embryos. These res ults indicate that the assembly and/or organization of cortical microtubule s in fertilized Xenopus eggs and subsequent specification of the dorsoventr al axis are dependent upon XMAP230. (C) 1999 Academic Press.