The Drosophila melanogaster attP40 docking site and derivatives are insertion mutations of msp-300

Abstract

The ɸC31 integrase system is widely used in Drosophila melanogaster to allow transgene targeting to specific loci. Over the years, flies bearing any of more than 100 attP docking sites have been constructed. One popular docking site, termed attP40, is located close to the Nesprin-1 orthologue msp-300 and lies upstream of certain msp-300 isoforms and within the first intron of others. Here we show that attP40 causes larval muscle nuclear clustering, which is a phenotype also conferred by msp-300 mutations. We also show that flies bearing insertions within attP40 can exhibit decreased msp-300 transcript levels in third instar larvae. Finally, chromosomes carrying certain “transgenic RNAi project” (TRiP) insertions into attP40 can confer pupal or adult inviability or infertility, or dominant nuclear clustering effects in certain genetic backgrounds. These phenotypes do not require transcription from the insertions within attP40. These results demonstrate that attP40 and insertion derivatives act as msp-300 insertional mutations. These findings should be considered when interpreting data from attP40-bearing flies.

The effect of Drosophila attP40 background on the glomerular organization of Or47b olfactory receptor neurons

“…2022 ). In addition, this study also reported defects in muscle nuclei spacing in larval stages in the attP40 homozygous background, which phenocopies Msp300 mutants ( van der Graaf et al . 2022 ).…”

“…A recent study reported that flies homozygous for the attP40 -derived insertions had 50% reduction in Msp300 transcript levels and phenocopied the defects in larval muscle nuclei clustering in Msp300 mutants ( van der Graaf et al . 2022 ).…”

“…2022 ). These results suggest that the attP40 docking site and attP40 -based transgenes are insertional mutations of Msp300 gene ( van der Graaf et al . 2022 ).…”

“…Indeed, recent studies have raised issues related to landing site-associated effects. For example, van der Graaf et al . 2022 showed flies bearing two copies of attP40 -derived insertions also show decreased Msp300 transcript levels ( van der Graaf et al .…”

“…For example, van der Graaf et al . 2022 showed flies bearing two copies of attP40 -derived insertions also show decreased Msp300 transcript levels ( van der Graaf et al . 2022 ).…”