U.S. Department of Health and Human Services

Genetics of Organelle Biogenesis Section

Kevin F. O'Connell, Ph.D., Chief

​Research Images

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Centrosome amplification in a C. elegans embryo.

This video was recorded by Jyoti Iyer, a research fellow in the laboratory of Dr. Kevin O’Connell and shows the first few cell cycles of a C. elegans embryo that lacks the protein phosphatase regulator SDS-22.   The embryo expresses GFP::SPD-2, which marks centrosomes in green and mCherry::Histone, which marks chromatin in red. Centrosomes initially duplicate properly yielding 2 centrosomes per cell through the two cell stage.  Centrosomes eventually over-duplicate giving rise to more than two centrosomes per cell at the four cell stage. From Peel N., Iyer J., Naik A., Dougherty M. P., Decker M., O'Connell K. F., 2017 Protein Phosphatase 1 Down Regulates ZYG-1 Levels to Limit Centriole Duplication. PLoS Genet. 13: e1006543.

Centrosome duplication in a C. elegans embryo.

This video was recorded by Nina Peel, a postdoctoral fellow in the laboratory of Dr. Kevin O’Connell and shows the first few cell cycles of a wild-type C. elegans embryo.   The embryo expresses GFP::SPD-2, which marks centrosomes in green and mCherry::Histone, which marks chromatin in red. Notice that at the end of the first cell cycle, each centrosome duplicates precisely and resolves into two daughter centrosomes. These daughter centrosomes migrate around the DNA to direct chromosome segregation during the next cell cycle.

Spindle assembly in a C. elegans embryo.

This time-lapse recording of a wild-type C. elegans embryo expressing GFP::Tubulin was produced in the laboratory of Kevin O’Connell.  The video begins with the maternal and paternal pronuclei uniting at the posterior of the embryo.  Two microtubule asters formed by centrosomes associated with the paternal pronucleus grow in size and set up the first mitotic spindle. At the end of the first cell cycle, the spindle disassembles as each centrosome duplicates giving rise to another round of bipolar spindle formation at the two-cell stage.

Centrosome amplification in a C. elegans embryo

A four-cell C. elegans sds-22 mutant embryo with extra centrosomes.  This is from our paper: Peel N., Iyer J., Naik A., Dougherty M. P., Decker M., O'Connell K. F., 2017 Protein Phosphatase 1 Down Regulates ZYG-1 Levels to Limit Centriole Duplication. PLoS Genet. 13: e1006543.

A four-cell C. elegans sds-22 mutant embryo with extra centrosomes.Enlarge
Electron micrograph of a C. elegans mother centriole

An electron micrograph of a C. elegans embryonic centriole. From: O'Connell K. F., Caron C., Kopish K. R., Hurd D. D., Kemphues K. J., Li Y., White J. G., 2001 The C. elegans zyg-1 gene encodes a regulator of centrosome duplication with distinct maternal and paternal roles in the embryo. Cell 105: 547–558.

An electron micrograph of a C. elegans embryonic centriole.Enlarge
Bipolar and monopolar spindle assembly in wild-type and mutant C. elegans embryos

Images of one- and two-cell C. elegans embryos stained for microtubules (red) and DNA (blue). Embryos on left are wild type and possess bipolar spindles. Embryos on right lack the kinase ZYG-1 and have monopolar spindles.

Images of one- and two-cell C. elegans embryos stained for microtubules (red) and DNA (blue).Enlarge
Microtubule organization in early C. elegans embryos

C. elegans embryos stained for microtubules (green), SPD-2 (red/yellow) and DNA (blue). From: Kemp C. A., Kopish K. R., Zipperlen P., Ahringer J., O'Connell K. F., 2004 Centrosome maturation and duplication in C. elegans require the coiled-coil protein SPD-2. Dev. Cell 6: 511–523.

C. elegans embryos stained for microtubules (green), SPD-2 (red/yellow) and DNA (blue).Enlarge