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Characterization of mid-spindle microtubules during furrow positioning in early cleavage period zebrafish embryos

Published online by Cambridge University Press:  08 October 2004

Karen W. Lee
Affiliation:
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, PRC
Steven M. Ho
Affiliation:
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, PRC
Carey H. Wong
Affiliation:
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, PRC
Sarah E. Webb
Affiliation:
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, PRC
Andrew L. Miller
Affiliation:
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, PRC

Abstract

We report evidence to suggest that during the first few meroblastic cell divisions in zebrafish embryos a dynamic population of central-spindle microtubules serve a crucial function in positioning the cleavage furrow at the surface of the blastoderm. Originating from the mid-zone of the mitotic spindle they develop into what we term a mid-spindle ‘pre-furrowing microtubule array’ that expands upward and outward from the spindle mid-zone towards the blastodisc surface. We suggest that this structure transmits positional information to the blastodisc cortex that results in the correctly positioned assembly of the cytokinetic contractile apparatus. We also propose that the pre-furrowing microtubule array then develops into a furrow-ingression microtubule array that helps direct and assemble the deepening furrow as it cuts its way through the blastodisc. Due to the location of its origin, the pre-furrowing microtubule array serves to successfully separate the daughter nuclei and thus equally divide the blastoderm. Furthermore, co-localization with elements of the cortical endoplasmic reticulum and their inositol 1,4,5-trisphosphate receptors suggests that the pre-furrowing microtubule array may also play a role in organizing localized Ca2+ transients that have been shown to be essential to the furrow positioning, propagation and deepening process during cytokinesis in zebrafish embryos.

Type
Research Article
Copyright
2004 Cambridge University Press

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