B6.129S4-Nos1^tm1Plh/J

Stock number: 002986
Product name: nNOS KO
Research areas: Diabetes and Obesity Research, Neurobiology Research

Description

nNos KO mice may useful when studying structure and function of neurons and their synaptic connections in the brain and periphery.

Detailed description

The nitric oxide signaling molecule produced by the neuronal Nos1 gene is widely expressed, affecting diverse systems. The knockout of this gene has been shown to affect such normal functions as cognition and behavior, long-term memory, cortical development, colonic motility, skeletal muscle contractility, ovarian cycle regulation, cardiac/cardiovascular function, and certain immune system responses. Western blots of brain homogenates from homozygous mutant mice showed no detectable protein. However, splice variants are expressed and variable low levels of NOS activity are seen in the brain.

Heterozygous mice are viable and fertile, while some lethality is seen in homozygotes due to stomach hypertrophy. The first publication describing this knock-out reported that mutants have enlarged stomachs with hypertrophy of the pyloric sphincter and the circular muscle layer (Huang et al., 1993). Male homozygotes of this strain were initially reported to be more aggressive than control mice, but this has been since attributed to heterogeneity of the stock before it was sufficiently backcrossed to the C57BL/6J genetic background. The C57BL/6J-congenic strain at The Jackson Laboratory (Stock No. 002986) shows normal behavior in this regard.

The Jackson Laboratory colony reports homozygous males may exhibit seizure-like activity starting around 14 weeks of age, and may be non-productive or found dead beginning around the same time. Approximately 60% of homozygous males survive to retirement age. Our historical data indicates we discontinued mating homozygous females as they were frequently non-productive or found dead. It is not determined if the observed homozygous lethality is from seizure activity, gastric issues or another cause.

The Jackson Laboratory preferred mating scheme for Stock No. 002986 is breeding heterozygous mice together, or by breeding heterozygous females to homozygous males. Breeding heterozygous mice together has resulted in variable Mendelian ratios of homozygous pups (e.g., ~10% in September 2019 but ~24% in September 2020). Of note, we attempted breeding homozygotes together and found they generated offspring at a much slower rate.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for this strain. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.

Development

A targeting vector was designed to replace exon 1 of the nitric oxide synthase 1, neuronal (Nos1) gene with a neomycin cassette. This exon encodes the initiation site and amino acids 1 - 159 of the protein. The targeting vector was electroporated into 129S4/SvJae -derived Jl ES cells that were injected into C57BL/6 blastocysts. Injected blastocysts were implanted in (C57BL/6 x DBA/2)Fl mice. Chimeric progeny were backcrossed to C57BL/6 mice. Some mice were further backcrossed to C57BL/6J mice (Stock No. 000664) for more than 10 generations to produce this Stock No. 002986.

Allele

Symbol: Nos1^tm1Plh
Name: targeted mutation 1, Paul L Huang
MGI accession ID: MGI:1857227
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Nos1
Marker name: nitric oxide synthase 1, neuronal
Chromosome: 5
Strain of origin: 129S4/SvJae
Molecular note: A neomycin cassette replaced exon 1. This exon encodes the initiation site and amino acids 1 - 159 of the protein. Northern blots of brain homogenates from homozygous mutant mice showed no detectable mRNA. Western blots of brain homogenates from homozygous mutant mice showed no detectable protein. However, splice variants are expressed and variable low levels of NOS activity are seen in the brain.