growth/size/body
• mice have 20-30% reduced body weight compared to heterozygotes or wild-type
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vision/eye
• cone photoreceptors are still found at 20 months but in greatly reduced numbers relative to 2-month old mutants where photoreceptors retain their normal shape
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• a shortening of rod outer segments (ROS) is observed as early as 4 weeks of age at onset of degeneration
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• at 5 months of age, thinning of outer nuclear layer containing photoreceptor nuclei occurs
• by 20 months of age, only 3-8 rows of nuclei remain in outer nuclear layer
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• slow degeneration is observed, beginning at ~4 weeks
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• single photon response from rods are larger and longer than control rods (time to peak 280 msec for Pde6b-null rods vs 213 msec for control)
• half-maximal flash strengths are lower in mutant rods
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• under photopic conditions, cone response is strongly diminished; most intense flash produces a b-wave with amplitude one-third of normal size
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• under scotopic (dim light) conditions, a-wave amplitudes are lower than in wild-type at intensities higher than -1.03 log cd/s/m-2; b-wave amplitudes decrease at intensities higher than -1.03 log cd/s/m-2
• in double-flash experiments, b-wave does not recover from primary flash with interstimulus intervals from 600 msec to 5 seconds; with intervals up to 20 minutes, b-wave of second response does not its reach normal amplitude
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nervous system
• cone photoreceptors are still found at 20 months but in greatly reduced numbers relative to 2-month old mutants where photoreceptors retain their normal shape
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• a shortening of rod outer segments (ROS) is observed as early as 4 weeks of age at onset of degeneration
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