In Chapter 02 titled “The GAL4 System: A Versatile System for the Manipulation and Analysis of Gene Expression”, there was an error with the formatting in figures 3 and 4. This has been changed to as follows:

Fig. 3
figure 1

Clonal analysis. (a) Expression of UAS constructs in clones can be achieved using FLP-out GAL4. Heat shock at 37 °C induces expression of a heat shock-inducible FLP recombinase. The recombinase acts on the FLP-out cassette catalyzing recombination between direct FRT repeats. Recombination removes the yellow marker and the transcription termination signals, allowing the expression of GAL4 under control of the Actin promoter. (b) Positively marked mutant clones can be made using MARCM. Heat shock at 37 °C induces expression of FLP recombinase that catalyzes recombination between FRTs on homologous chromosomes carrying either the mutation of interest or a tubGAL80 construct. Segregation of the GAL80 from the mutation into different daughter cells relieves repression of a GAL4 inducible marker in the mutant cells, labeling the mutant clone

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Fig. 4
figure 2

Repressing genes using the GAL4 system. (a) RNAi-based gene knockdown can be achieved by expressing inverted repeats complementary to the gene of interest. These repeats will fold into a long double-stranded RNA that will be processed to produce multiple siRNAs against the target gene. (b) More specific knockdown can be achieved using UASshmiR constructs. A single targeting siRNA is cloned into the miR-1 backbone. Processing by cellular machinery produces only that siRNA. (c) Tissue-specific gene knock-outs can be achieved using a GAL4-dependent version of Cas9 and the CRISPR/Cas9 gene targeting. A ubiquitously expressed chimeric gRNA targeting the gene of interest is expressed in conjunction with UAS-cas9 resulting in biallelic gene targeting where Cas9 is driven

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