PMC7542348_01
Ivermectin-induced silencing of Ela1-CreER in the pancreas. Representative immunofluorescent images of postnatal day 21 pancreata. Sections are labeled with antibodies against amylase (red) for acinar cells and YFP (green) for expression of the Rosa26lsl-YFP reporter of Cre activity. Colabeled with DAPI (blue, faint) for nuclei. Genotype and treatment group are indicated above images. No groups were administered tamoxifen at any time. Column 1 shows no YFP expression in untreated mice lacking the Ela1-CreER transgene (3/3 mice analyzed). Column 2 shows constitutive Ela1-CreER activity in untreated mice (7/7 double transgenic mice analyzed). Column 3 shows constitutive Ela1-CreER activity in spite of ivermectin treatment (2/6 double trangenic mice analyzed) whereas column 4 shows lost constitutive Ela1-CreER activity following ivermectin treatment (4/6 double transgenic mice analyzed)
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PMC7542348_01_42826_2020_69_Fig1_HTML.jpg
Fig1
However, 4/6 double-transgenic mice raised on the ivermectin diet had no detectable YFP expression (Fig. 1) indicating that, by an unknown mechanism, expression, or activity, of the Ela1-CreER is reduced or absent.
Ivermectin and/or selamectin-induced activation of Emx1-CreER and Gli1-CreER in the V-SVZ. Representative immunofluorescent images of postnatal day 7 dorsal (above) and ventral (below) V-SVZ. Sections are labeled with antibodies against GFAP (green) for glia/stem cells and tdTomato (red) for for expression of the Ai14 reporter of Cre activity. Colabeled with DAPI (blue) for nuclei. Region, genotype, and treatment group are indicated above images. No groups were administered tamoxifen at anytime. Tissue autofluoresence is visible as an artifact of imaging in control animals. Select tdTomato+ cells are indicated with arrows
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PMC7542348_01_42826_2020_69_Fig2_HTML.jpg
Fig2
Immunofluorescent labeling showed aberrant tdTomato reporter expression in the absence of tamoxifen in both the dorsal (top) portion of the niche and within the corpus callosum of Emx1-CreER; Ai14 mice treated with either an ivermectin diet or topical selamectin (Fig. 2). In the Gli1-CreER; Ai14 pup, the ventral (bottom) subregion of the niche displayed aberrant tdTomato expression in the absence of tamoxifen treatment in the presence of ivermectin (Fig. 2).