Identification of the gene and the mutation responsible for the mouse nob phenotype.
OBJECTIVE
The available evidence indicates that the naturally occurring mouse mutant nob (no b-wave) provides an animal model for the complete form of human X-linked congenital stationary night blindness (CSNB1). The goals of the present study were to identify the nob gene defect, to characterize the expression pattern of the involved gene, and to assess visual sensitivity in nob mice.


METHODS
Positional cloning, screening of candidate genes, and sequencing were used to identify the nob gene. The expression pattern of the nyx gene was examined with Northern blot analysis and in situ hybridization. Visual sensitivity was measured with an active avoidance behavioral test.


RESULTS
The nob phenotype is caused by an 85-bp deletion in the mouse nyx gene, which encodes the nyctalopin protein. Expression of nyx was most abundant in the retina and, in particular, in the inner nuclear layer. The nyctalopin protein contains 11 leucine-rich repeats and is flanked by cysteine rich regions, which identifies it as a member of the small leucine rich proteoglycan family. Behavioral testing shows that nob mice have a significant decrease in visual sensitivity.


CONCLUSIONS
The nob mouse is a model for human CSNB1. This model will be useful in defining the role of nyctalopin in signal transmission between photoreceptors and retinal bipolar cells.
Gregg
Ronald G
RG
Department of Biochemistry and Molecular Biology, University of Louisville, 319 Abraham Flexner Way, Louisville, KY 40202, USA. ron.gregg@louisville.edu
Mukhopadhyay
Suparna
S
Candille
Sophie I
SI
Ball
Sherry L
SL
Pardue
Machelle T
MT
McCall
Maureen A
MA
Peachey
Neal S
NS
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D009154:Mutation; D009755:Night Blindness / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011509:Proteoglycans / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000737:chemistry / Q000502:physiology; D017384:Sequence Deletion; D014785:Vision, Ocular / Q000502:physiology
D005136:Eye Proteins; C416505:NYX protein, human; D011509:Proteoglycans; D012333:RNA, Messenger