Transcription and splicing dynamics during early Drosophila development

Area of Science:

• Molecular Biology
• Developmental Biology
• Genomics

Background:

• Cotranscriptional splicing is widespread across species.
• Previous studies primarily used yeast or cultured metazoan cells.
• Early embryonic development presents unique transcriptional and splicing landscapes.

Purpose of the Study:

• To investigate cotranscriptional splicing dynamics in early Drosophila melanogaster embryos.
• To map RNA polymerase II (Pol II) positions during splicing events.
• To understand how intron size and genomic context affect splicing kinetics.

Main Methods:

• Adaptation of native elongating transcript sequencing (NET-seq) for Drosophila embryos.
• Analysis of splicing dynamics relative to Pol II position.
• Comparison of splicing in early vs. late embryonic transcripts.

Main Results:

• Revealed heterogeneity in splicing timing, with some introns spliced immediately and others delayed.
• Demonstrated intron definition across all intron sizes, irrespective of Pol II position.
• Observed differences in transcription termination based on gene isolation or overlap with convergent genes.

Conclusions:

• Early Drosophila development exhibits dynamic and heterogeneous cotranscriptional splicing.
• Intron size and gene organization influence splicing kinetics and transcription termination.
• NET-seq provides novel insights into the interplay of transcription and splicing in vivo.