Morphogenesis after heat shock during the cell cycle ofLymnaea: A new interpretation

Area of Science:

• Developmental Biology
• Cell Biology
• Embryology

Background:

• Cell cycle regulation is crucial for normal embryonic development.
• Environmental stressors can impact cell division and developmental processes.
• Understanding heat shock effects on early embryogenesis provides insights into cellular resilience.

Purpose of the Study:

• To investigate the effects of heat shock on the cell cycle and morphogenesis during early cleavage stages in Lymnaea.
• To determine the timing of sensitivity to heat shock during the cell cycle.
• To elucidate the relationship between heat shock, mitotic abnormalities, and developmental malformations.

Main Methods:

• Embryos of Lymnaea were subjected to controlled heat shock (37.0-38.0°C, 10 min) during the third and fourth cleavage cycles.
• Cell cycle duration and morphological development were monitored.
• Mitotic abnormalities, including chromosome segregation errors, were analyzed.

Main Results:

• Heat sensitivity of the cell cycle and morphogenesis was found to be periodic, with maxima at the beginning of the cycle, G2-phase, and prometaphase.
• Heat shock applied before metaphase allowed for cell cycle extension and normal morphogenesis.
• Heat shock applied at or after metaphase resulted in delayed cell division, severe mitotic disturbances, and abnormal morphogenesis.

Conclusions:

• Heat shock significantly disrupts cell cycle processes in developing Lymnaea embryos.
• The timing of heat shock application relative to mitosis determines the outcome: recovery or irreversible damage.
• Mitotic abnormalities caused by late-stage heat shock lead to specific malformations dependent on blastomere fate.