mortality/aging
• all homozygotes die within 24 hrs after birth in the absence of gross anatomic defects in limbs, spinal cord, eye, and brain
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homeostasis/metabolism
respiratory system
• newborn homozygotes display irregular and obstructive breathing
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behavior/neurological
• 11 of 13 newborn homozygotes contain no milk in their stomachs
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nervous system
N |
• surprisingly, homozygotes display normal brain morphology, including:
• no significant alterations in layers I-VI of the cerebral cortex, layers CA1-CA3 of the hippocampus, dentate gyrus, neurocortical neuroepithelium, subventricular zone, cerebellum or brainstem
• no significant size variations in individual nuclei (paraventricular nucleus, supraoptic nucleus, ventromedial hypothalamic nucleus), and in pituitary
• normal cell proliferation and distribution of neurons, glia, radial glia, and neuronal progenitors
• normal distribution and axonal projections in the cortex and hippocampus
• normal growth kinetics of neural stem cells when cultivated in vitro
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endocrine/exocrine glands
N |
• at E18.5, one day prior to birth, the pancreas of mutant embryos was normal in size and gross appearance; hematoxylin-eosin staining revealed no obvious morphological discrepancy, and immunofluorescent
staining for acinar (Amylase), ductal (Mucin-1) and mesenchymal
(Vimentin) markers detected no differences compared to controls
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• staining for Ki-67, a marker of actively proliferating cells, revealed a ~3-fold decrease in the proliferation of insulin-positive cells in mutant embryos at E18.5 compared to controls
• the proliferation of Pdx1-positive pancreatic progenitors at E12.5 is unaffected in the mutants, a result that is consistent with the observation that the overall size of the pancreas was unchanged
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• at E18.5, a 63% reduction in glucagon-producing alpha-cells is seen in mutant pancreases relative to controls
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• at E18.5, a 67% reduction in the number of insulin-producing beta-cells is seen in mutant pancreases relative to controls
• the remaining beta-cells in the mutant embryos appeared to be fully
differentiated, as judged by their expression of Glut2, a characteristic
marker of mature beta-cells
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• at E18.5, endocrine cells are still clustered into islet structures, but the size of the aggregates is reduced in mutants
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cellular
• staining for Ki-67, a marker of actively proliferating cells, revealed a ~3-fold decrease in the proliferation of insulin-positive cells in mutant embryos at E18.5 compared to controls
• the proliferation of Pdx1-positive pancreatic progenitors at E12.5 is unaffected in the mutants, a result that is consistent with the observation that the overall size of the pancreas was unchanged
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