Men with normal color vision vary widely in the ratio of long- (L) to middle-wavelength sensitive (M) cones. This variation provides opportunities to test models for the mechanism that produces L versus M cones during development. The L and M photopigment genes lie in a tandem array. Each gene has a promoter, and upstream of each array there is a genetic element, termed the locus control region...

Estimates of L:M cone ratio for males with normal color vision were derived using the flicker-photometric electroretinogram (ERG). These were obtained by best fitting ERG spectral sensitivity functions to a weighted sum of long (L)- and middle (M)-wavelength-sensitive cone spectral absorption curves. Using the ERG, measurements can be made with extremely high precision, which leaves variation i...

PURPOSE To determine a time window in the rhodopsin knockout (Rho(-/-)) mouse during which retinal function is already sufficiently developed but cone degeneration is not yet substantial, thus representing an all-cone retina. METHODS Electroretinograms (ERGs) were obtained from 14 homozygous Rho(-/-) mice and eight C57Bl/6 control mice. The same individuals were tested every 7 days, beginning...

Seven domestic cats with feline central retinal degeneration (FCRD) were investigated by ophthalmoscopy, fluorescein angiography, electroretinography, and light and electron microscopy. Little or no increase in lesion size was observed ophthalmoscopically over periods as long as four years. Five cats showed normal rod electroretinographic (ERG) responses and abnormal cone responses. In one cat ...

PURPOSE To characterize molecular and cellular changes in the mouse retina caused by the genetic deletion of the cone cyclic nucleotide-gated channel (CNG) subunit CNGA3. METHODS Retinas of wild-type and CNGA3-deficient (CNGA3(-/-)) mice from 9 days up to 22 months of age were analyzed by immunohistochemistry, electron microscopy, and molecular biological methods. RESULTS CNGA3(-/-) cones f...

PURPOSE To identify changes in S- and M-sensitive cone opsin gene expression following retinal detachment (RD) and reattachment. METHODS Cat retinas were detached for 1, 3, 7, or 28 days, or reattached after 1 h, 1 day, or 3 days of RD and fixed in 4% paraformaldehyde. Pieces of mid-peripheral retina were removed from the same region of each detached, normal (attached), and reattached retina ...

1. Where we are: Segre classes of vector bundles, and Segre classes of cones 1 1.1. Segre classes of cones 1 2. What the “functoriality of Segre classes of subschemes” buys us 2 2.1. The multiplicity of a variety along a subvariety 2 3. Deformation to the normal cone 3 3.1. The construction 3 4. Specialization to the normal cone 5 4.1. Gysin pullback for local complete intersections 6 4.2. Inte...

Utilizing dual descriptions of the normal cone of convex optimization problems in conic form, we characterize the vertices of semidefinite representations arising from Lovász theta body, generalizations of the elliptope, and related convex sets. Our results generalize vertex characterizations due to Laurent and Poljak from the 1990’s. Our approach, focused on the dimension of the normal cone, a...