Low temperature mitigates cardia bifida in zebrafish embryos

Area of Science:

• Developmental biology
• Cardiovascular research
• Zebrafish models

Background:

• Coordinated cardiomyocyte migration and cardiac cone formation are crucial for heart tube development.
• Gene regulatory mechanisms controlling myocardial migration and cardiac cone timing are not fully understood.

Purpose of the Study:

• Investigate gene regulatory mechanisms in zebrafish myocardial migration.
• Determine how cardiac cone formation timing is regulated.
• Identify factors influencing cardia bifida, a heart development defect.

Main Methods:

• Ethylnitrosourea screening in zebrafish to identify mutants.
• Analysis of a hypomorphic mil (s1pr2)/edg5 allele (s1pr2(as10)).
• Low-temperature rescue experiments (22.5°C) on mutant embryos.
• Gene expression analysis using DNA microarrays and digital gene expression.
• Loss-of-function studies and mRNA/protein rescue experiments.
• Assessment of reactive oxygen species (ROS) using N-acetyl cysteine (NAC).

Main Results:

• The s1pr2(as10) mutant exhibits cardia bifida due to reduced mil/edg5 expression.
• Low temperature (22.5°C) rescues cardia bifida in s1pr2(as10), gata5, and bon morphants.
• Low temperature mitigates cardia bifida by regulating extracellular matrix genes: fibronectin 1, tenascin-c, and tenascin-w.
• N-acetyl cysteine (NAC) reduces the mitigating effect of low temperature, suggesting ROS involvement.

Conclusions:

• Temperature plays a role in coordinating heart tube and somitogenesis development.
• Extracellular matrix genes (fibronectin 1, tenascin-c, tenascin-w) are critical for preventing cardia bifida.
• Low temperature rescues cardia bifida, potentially by modulating ROS and extracellular matrix gene expression.