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Updated: Jul 27, 2025
High Throughput Microinjections of Sea Urchin Zygotes
Published on: January 21, 2014
MICROINJECTION OF COLCHICINE INTO SEA URCHIN EGGS
1Biological Laboratory, Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan.
Abstract:
Inhibition of cleavage by colchicine was examined by microinjecting colchicine solution into one of the blastomeres of a sea urchin egg at the two-cell stage. Cleavage was inhibited if the microinjection was made before a critical point prior to the cleavage, whereas cleavage occurred in spite of the destruction of the mitotic apparatus if the microinjection was made after the critical point. The critical point was 10 min before the mid-stage of the cleavage in Clypeaster japonicus and 8 min before the mid-stage in Temnopleurus toreumaticus at 20 ± 1°C, corresponding to the beginning of anaphase. The threshold for the cleavage inhibition of colchicine was estimated to be 3 × 10-5 M to 3 × 10-6 M in final concentration in the cell.
Insights
Colchicine inhibits sea urchin egg cleavage when injected before anaphase begins. However, eggs can still cleave if colchicine is administered after this critical point, even if the mitotic apparatus is disrupted.
Area of Science:
- Developmental Biology
- Cell Biology
- Marine Biology
Background:
- Cell division, or cleavage, is a fundamental process in early embryonic development.
- Colchicine is a known inhibitor of microtubule polymerization, crucial for cell division.
- Understanding the precise timing of cellular events is key to comprehending developmental processes.
Purpose of the Study:
- To investigate the effect of colchicine on sea urchin egg cleavage.
- To determine the critical time point during the cell cycle at which colchicine inhibits cleavage.
- To establish the concentration threshold for colchicine's inhibitory effects on embryonic cell division.
Main Methods:
- Microinjection of colchicine solution into blastomeres of two-cell stage sea urchin embryos (Clypeaster japonicus and Temnopleurus toreumaticus).
- Observation and timing of cleavage inhibition relative to the cell cycle.
- Determination of colchicine concentration thresholds for observed effects.
Main Results:
- Cleavage inhibition occurred when colchicine was microinjected before a specific critical point preceding cleavage.
- Cleavage proceeded despite mitotic apparatus destruction if colchicine was microinjected after this critical point.
- The critical point was identified as approximately 10 minutes (C. japonicus) and 8 minutes (T. toreumaticus) before mid-cleavage, coinciding with anaphase onset.
- The threshold concentration for colchicine's cleavage inhibition was estimated between 3 × 10⁻⁵ M and 3 × 10⁻⁶ M.
Conclusions:
- The timing of colchicine administration relative to the cell cycle is critical for its inhibitory effect on sea urchin egg cleavage.
- Sea urchin embryos exhibit a window of sensitivity to colchicine, primarily around the onset of anaphase.
- These findings provide insights into the temporal regulation of cell division during early embryogenesis and the mechanism of colchicine action.
