E imaged at 4, 8, and 12 weeks (Figure 5A). The bioluminescence intensity was significantly enhanced in the HFD-fed mice at 8 weeks (RD: 1.9760.806106 photons/sec; HFD: 7.4261.526106 photons/sec; P = 0.022) and accompanied by an increase in the body fat ratio (RD: 7.862.9 ; HFD: 27.965.4 ; P = 0.019) and in FBG levels (RD: 125628 mg/dL; HFD: 271635 mg/dL; P = 0.018) (Figure 5B?E). However, although the rate of increase in the signal after 8 weeks was substantially higher in the HFD-fed mice than in the RD-fed mice (379 ), the rate of increase in b-cell 
mass differed slightly (121 ; RD: 1.3160.28 mg; HFD: 1.5960.26 mg; P = 0.49) (Figure 5F). Immunohistochemical 12926553 analysis of islets from HFD-fed mice showed a similar pattern to control islets in insulin and luciferase reactivity, so that we could not find a clear reason for the discrepancy in the rate of increase Tunicamycin between the BLI signal and b-cell mass (Figure 5G) Interestingly, some mice, especially HFD-treated mice, developed dispersed luminescence from the central to right abdominal regions as shown in Figure 5, probably owing to the signal emission from the duodenum lobe that is ventrally covered by the liver and undetectable in MIP-Luc-VU mice.Finally, we examined whether intrahepatic insulin gene activity is detected in Ins1-luc BAC transgenic mice by b-cell-related gene transfer. The Pdx1, NeuroD, and MafA genes were transferred by adenovirus vectors, and serial BLI was monitored before and after infection. This gene combination was selected according to a previous study [28]. The adenovirus-mediated gene transfer induced a BLI signal in the hepatic region for more than 1 week (Figure 6A). The signal was order Madrasin identified as originating from the liver by imaging of extracted tissues 3 days after infection and by immunohistochemical analysis using anti-insulin antibody (Figure 6B, C). Thus, these results indicate that Ins1-luc BAC transgenic mice could be used for monitoring intrahepatic insulin gene activity in vivo.DiscussionIn this study, we generated and characterized novel 23727046 Ins1-luc BAC transgenic mice in which b cells specifically express luciferase under Ins1 locus control. Bioluminescence emission from the islets altered in response to both b-cell destruction and augmentation. Given also the absence of obvious phenotypic changes such as in islet morphology, b-cell insulin content, and secretory response by secretogens, these results indicate that these mice could be useful as a bioluminescence reporter line for b-cell studies. We found that the bioluminescence intensity correlated well with the number of islets in vitro. However, although some damaged b cells remained after STZ treatment, luminescence from the area corresponding to the pancreas was not detectable. In addition, in the HFD model, the rates of increase of the BLI signal and the b-cell mass were hugely discrepant. These results suggest that in vivo BLI in the mice could provide only relative changes in b-cell mass but not absolute quantification under pathological conditions. In fact, the BLI intensity in another b-cell-specific reporter mouse has been shown to be affected by other factors, including chronic hyperglycemia, inflammatory mediators, and extrapancreatic fat mass [10]. As far as we know, the Ins1-luc BAC transgenic mouse is the first transgenic line containing a reporter driven by the Ins1 locus. The approximate bioluminescence intensities emitted from the pancreatic islets of MIP-Luc mice developed by Park et.E imaged at 4, 8, and 12 weeks (Figure 5A). The bioluminescence intensity was significantly enhanced in the HFD-fed mice at 8 weeks (RD: 1.9760.806106 photons/sec; HFD: 7.4261.526106 photons/sec; P = 0.022) and accompanied by an increase in the body fat ratio (RD: 7.862.9 ; HFD: 27.965.4 ; P = 0.019) and in FBG levels (RD: 125628 mg/dL; HFD: 271635 mg/dL; P = 0.018) (Figure 5B?E). However, although the rate of increase in the signal after 8 weeks was substantially higher in the HFD-fed mice than in the RD-fed mice (379 ), the rate of increase in b-cell mass differed slightly (121 ; RD: 1.3160.28 mg; HFD: 1.5960.26 mg; P = 0.49) (Figure 5F). Immunohistochemical 12926553 analysis of islets from HFD-fed mice showed a similar pattern to control islets in insulin and luciferase reactivity, so that we could not find a clear reason for the discrepancy in the rate of increase between the BLI signal and b-cell mass (Figure 5G) Interestingly, some mice, especially HFD-treated mice, developed dispersed luminescence from the central to right abdominal regions as shown in Figure 5, probably owing to the signal emission from the duodenum lobe that is ventrally covered by the liver and undetectable in MIP-Luc-VU mice.Finally, we examined whether intrahepatic insulin gene activity is detected in Ins1-luc BAC transgenic mice by b-cell-related gene transfer. The Pdx1, NeuroD, and MafA genes were transferred by adenovirus vectors, and serial BLI was monitored before and after infection. This gene combination was selected according to a previous study [28]. The adenovirus-mediated gene transfer induced a BLI signal in the hepatic region for more than 1 week (Figure 6A). The signal was identified as originating from the liver by imaging of extracted tissues 3 days after infection and by immunohistochemical analysis using anti-insulin antibody (Figure 6B, C). Thus, these results indicate that Ins1-luc BAC 
transgenic mice could be used for monitoring intrahepatic insulin gene activity in vivo.DiscussionIn this study, we generated and characterized novel 23727046 Ins1-luc BAC transgenic mice in which b cells specifically express luciferase under Ins1 locus control. Bioluminescence emission from the islets altered in response to both b-cell destruction and augmentation. Given also the absence of obvious phenotypic changes such as in islet morphology, b-cell insulin content, and secretory response by secretogens, these results indicate that these mice could be useful as a bioluminescence reporter line for b-cell studies. We found that the bioluminescence intensity correlated well with the number of islets in vitro. However, although some damaged b cells remained after STZ treatment, luminescence from the area corresponding to the pancreas was not detectable. In addition, in the HFD model, the rates of increase of the BLI signal and the b-cell mass were hugely discrepant. These results suggest that in vivo BLI in the mice could provide only relative changes in b-cell mass but not absolute quantification under pathological conditions. In fact, the BLI intensity in another b-cell-specific reporter mouse has been shown to be affected by other factors, including chronic hyperglycemia, inflammatory mediators, and extrapancreatic fat mass [10]. As far as we know, the Ins1-luc BAC transgenic mouse is the first transgenic line containing a reporter driven by the Ins1 locus. The approximate bioluminescence intensities emitted from the pancreatic islets of MIP-Luc mice developed by Park et.