Faculty Opinions recommendation of Kinesin-1 prevents capture of the oocyte meiotic spindle by the sperm aster.

In this abstract we Illustrate how same-section correlative light and high voltage electron microscopy (HVEM) of serial 0.25-0.50-μm sections can answer questions which are difficult to approach by EM of 60-100 nm sections.Starfish (Pisaster and Asterlas) eggs are fertilized at meiosis I when the oocyte contains two maternal centrosomes (e.g., asters) which form the poles of the first meiotic spindle. Immediately after fertilization a sperm aster is assembled in the vicinity of the male pronucleus and persists throughout meiosis. At syngamy the sperm aster splits to form the poles of the first mitotic spindle. During this time the functional and replicative properties of the maternal centrosome, inherited from the last meiotic division, are lost. The basis for this differential stability, of male and female centrosomes in the same cytoplasm, is a mystery.

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Kinesin-1 Prevents Capture of the Oocyte Meiotic Spindle by the Sperm Aster

Developmental Cell ◽

10.1016/j.devcel.2012.01.010 ◽

2012 ◽

Vol 22 (4) ◽

pp. 788-798 ◽

Cited By ~ 19

Author(s):

Karen L.P. McNally ◽

Amy S. Fabritius ◽

Marina L. Ellefson ◽

Jonathan R. Flynn ◽

Jennifer A. Milan ◽

...

Keyword(s):

Meiotic Spindle ◽

Sperm Aster

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Failure of pronuclear migration and repeated divisions of polar body nuclei associated with MTOC defects in polo eggs of Drosophila

Journal of Cell Science ◽

10.1242/jcs.113.18.3341 ◽

2000 ◽

Vol 113 (18) ◽

pp. 3341-3350 ◽

Cited By ~ 8

Author(s):

M.G. Riparbelli ◽

G. Callaini ◽

D.M. Glover

Keyword(s):

Polar Body ◽

Motor Protein ◽

Meiotic Spindle ◽

Wild Type ◽

Female Meiosis ◽

Male Pronucleus ◽

Female Pronucleus ◽

Sperm Aster ◽

Meiosis I

The meiotic spindle of Drosophila oocytes is acentriolar but develops an unusual central microtubule organising centre (MTOC) at the end of meiosis I. In polo oocytes, this common central pole for the two tandem spindles of meiosis II was poorly organised and in contrast to wild-type failed to maintain its associated Pav-KLP motor protein. Furthermore, the polar body nuclei failed to arrest at metaphase, and the four products of female meiosis all underwent repeated haploid division cycles on anastral spindles. This was linked to a failure to form the astral array of microtubules with which the polar body chromosomes are normally associated. The MTOC associated with the male pronucleus was also defective in polo eggs, and the sperm aster did not grow. Migration of the female pronucleus did not take place and so a gonomeric spindle could not form. We discuss these findings in relation to the known roles of polo like kinases in regulating the behaviour of MTOCs.

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Probing the ultrastructure of the mitotic and meiotic spindle in eggs: An expeditious approach based on semi-thin (0.25 μm) serial sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076408 ◽

1983 ◽

Vol 41 ◽

pp. 552-555

Author(s):

Conly L. Rieder ◽

S. Bowser ◽

R. Nowogrodzki ◽

K. Ross ◽

G. Sluder

Keyword(s):

Small Sample Size ◽

Small Sample ◽

Meiotic Spindle ◽

Serial Sections ◽

Mitotic Apparatus ◽

Thin Sections ◽

Cell Cycles ◽

Ultrastructural Studies

Eggs have long been a favorite material for studying the mechanism of karyokinesis in-vivo and in-vitro. They can be obtained in great numbers and, when fertilized, divide synchronously over many cell cycles. However, they are not considered to be a practical system for ultrastructural studies on the mitotic apparatus (MA) for several reasons, the most obvious of which is that sectioning them is a formidable task: over 1000 ultra-thin sections need to be cut from a single 80-100 μm diameter egg and of these sections only a small percentage will contain the area or structure of interest. Thus it is difficult and time consuming to obtain reliable ultrastructural data concerning the MA of eggs; and when it is obtained it is necessarily based on a small sample size.We have recently developed a procedure which will facilitate many studies concerned with the ultrastructure of the MA in eggs. It is based on the availability of biological HVEM's and on the observation that 0.25 μm thick serial sections can be screened at high resolution for content (after mounting on slot grids and staining with uranyl and lead) by phase contrast light microscopy (LM; Figs 1-2).

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