REGULATION OF RIBOSOMAL RNA SYNTHESIS DURING TAIL REGRESSION IN ORGAN CULTURE

Area of Science:

• Developmental Biology
• Molecular Biology
• Amphibian Metamorphosis

Background:

• Hormone-induced metamorphosis in Xenopus laevis involves significant tissue remodeling.
• Tail regression is a key feature of prometamorphic larval development.

Purpose of the Study:

• To investigate the synthesis and degradation of ribosomal RNAs (rRNAs) in Xenopus laevis tail tips during triiodothyronine-induced metamorphosis.
• To understand the molecular mechanisms underlying RNA content changes in regressing tadpole tails.

Main Methods:

• Organ culture of early prometamorphic Xenopus laevis larval tail tips.
• Treatment with triiodothyronine to induce metamorphic responses.
• Measurement of RNA synthesis (3H-uridine incorporation) and precursor processing rates.

Main Results:

• Triiodothyronine treatment did not alter overall RNA synthesis rates.
• Processing of the 40S precursor rRNA was enhanced in hormone-treated tail tips.
• Synthesized ribosomal RNAs and transfer RNAs became susceptible to degradation in regressing tails.

Conclusions:

• Increased degradation of rRNA and tRNA contributes to the observed decrease in RNA content during tail regression.
• The study did not find evidence for asymmetric rRNA precursor processing in Xenopus tail muscle.