Mark E. Pennesi

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Molecular biological, histological and flicker electroretinographic results have established that mice have two cone photopigments, one peaking near 350 nm (UV-cone pigment) and a second near 510 nm [midwave (M)-cone pigment]. The goal of this investigation was to measure the action spectra and absolute sensitivities of the UV-cone- and M-cone-driven b-wave(More)
We targeted 266 CAG repeats (a number that causes infantile-onset disease) into the mouse Sca7 locus to generate an authentic model of spinocerebellar ataxia type 7 (SCA7). These mice reproduced features of infantile SCA7 (ataxia, visual impairments, and premature death) and showed impaired short-term synaptic potentiation; downregulation of(More)
PURPOSE To measure the dependence of the size of the pupils of mice on steady retinal illumination. METHODS Anesthetized C57BL/6 mice aged 7 to 8 weeks were placed in a ganzfeld chamber in darkness, and in monochromatic (510 nm) and white light whose intensity was varied more than 6 log units. The pupils of the mice were photographed with an infrared(More)
Bardet-Biedl syndrome (BBS) is an oligogenic syndrome whose manifestations include retinal degeneration, renal abnormalities, obesity and polydactylia. Evidence suggests that the main etiopathophysiology of this syndrome is impaired intraflagellar transport (IFT). In this study, we study the Bbs4-null mouse and investigate photoreceptor structure and(More)
Retinal bipolar cells are essential to the transmission of light information. Although bipolar cell dysfunction can result in blindness, little is known about the factors required for bipolar cell development and functional maturation. The basic helix-loop-helix (bHLH) transcription factor Bhlhb4 was found to be expressed in rod bipolar cells (RB).(More)
Visual transduction in retinal photoreceptors operates through a dynamic interplay of two second messengers, Ca(2+) and cGMP. Ca(2+) regulates the activity of guanylate cyclase (GC) and the synthesis of cGMP by acting on a GC-activating protein (GCAP). While this action is critical for rapid termination of the light response, the GCAP responsible has not(More)
BETA2/NeuroD1 is a basic helix-loop-helix transcription factor that is expressed widely throughout the developing nervous system. Previous studies have shown that BETA2/NeuroD1 influences the fate of retinal cells in culture. To analyze the effect of BETA2/NeuroD1 on the structure and function of the retina, we examined a line of BETA2/NeuroD1 knock-out(More)
The early loss of photoreceptors in some retinal degenerations in mice has been shown to have a profound effect on vascular development of the retina. To better characterize this relationship, we have examined the formation of retinal blood vessels during the first month of life in 8 lines of transgenic rats with different ages of onset and rates of(More)
Mediated by guanylate cyclase-activating proteins (GCAPs), cytoplasmic Ca2+ levels regulate the activity of photoreceptor guanylate cyclase (GC) and the synthesis of cGMP, the internal transmitter of phototransduction. When GCAP1 is expressed in transgenic mice on a GCAP null background, it restores the wild-type flash responses in rod photoreceptors. In(More)
We developed and characterized a mouse model of elevated intraocular pressure (IOP) to investigate the underlying cellular and genetic mechanisms of retinal ganglion cell (RGC) death. IOP was unilaterally increased in C57BL/6J mice by photocoagulation of the episcleral and limbal veins. IOP was measured using an indentation tonometer. RGC survival was(More)