In this study, researchers analyzed the effects of inserting a P element into the CG3011 gene on sleep duration in Drosophila melanogaster. They found that sleep duration was decreased when a P element was inserted into the CG3011 gene. Further analysis revealed that CG3011 encodes the serine hydroxymethyltransferase (SHMT) enzyme, which is involved in the synthesis of L-Ser25,26. The researchers generated mutations in the shmt gene using CRISPR-Cas9 and found that deleting all three isoforms of SHMT caused lethality, while introducing a STOP codon in the first coding exon of isoform A resulted in viable mutants. The mRNA level of isoform A SHMT was significantly decreased in the shmt-es mutants compared to wild type flies. The study used backcrossing to introduce the mutations into an isogenic Canton-S (CS) line and conducted further analysis on these mutants.