Cell Division: Pressure-induced reversal of the antimeiotic effects of heavy water in the oocytes of the starfish, Asterias forbesi

✍ Scribed by Douglas Marsland; Yukio Hiramoto

• Publisher: John Wiley and Sons
• Year: 1966
• Tongue: English
• Weight: 686 KB
• Volume: 67
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040670103

✦ Synopsis

Meiotic activity in the oocytes of the starfish, Asterias forbesi, may be blocked by immersion in deuterated sea water (60% or more) as is judged by a stoppage in the breakdown of the germinal vesicles and a failure of the cells to form persistent polar bodies. These anti-meiotic effects of heavy water were reversed in significant degree by application of suitable intensities (3,000 to 6,000 psi) of hydrostatic pressure. In this regard meiosis resembles mitosis, as studied previously in the first cleavage division of the sea urchin, Strongylocentrotus purpuratus.

In studying germinal vesicle breakdown, immersion of the Bocytes in deuterated (60, 70 and 80% DzO) sea water was initiated ten minutes after shedding and pressurization was established six minutes later. None of the non-pressurized deuterated cells showed complete breakdown of the germinal vesicle, whereas complete breakdown was observed in a significant percentage of the pressurized deuterated specimen.

In studying their capacity to form and maintain polar bodies, the iiocytes were deuterated 60 minutes after shedding and pressurized six minutes later. Maximum release from deuterational blockage, as judged by the percentage of persistent polar bodies after one hour of treatment, was as follows: 85% at 2,000 psi for 50% DzO; 65% at 2,500 psi, for 60% ; 77% at 3,000 psi for 70% ; 55% at 3,500 psi for 80% and 65% at 3,500 psi for 90%. Persistence of polar bodies in the non-pressurized deuterated cells did not exceed 15% in any medium containing 60% or more of DzO and the average persistence in such media was only 2.5%.

Basic mechanisms which may account for the observed effects are discussed.