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Print Friendly Two quantitative trait
loci (QTLs), Hipp1a and Hipp5a, modulate hippocampal size and number of
neurons in the dentate gyrus of mouse (Lu et al., 2001, J. Neurosci., vol.
21; www.nervenet.org). Both QTLs act globally and affect many parts of the
hippocampus. We now report new QTLs that have restricted effects on specific
hippocampal regions. Our biometric analysis is based on reconstructions and
unbiased cell counts taken bilaterally from 250 mice that belong to 32 BXD
recombinant inbred strains and two parental strains (C57BL/6J and DBA/2J).
Material was taken from the Mouse Brain Library (www.mbl.org). Even among
strains with the same hippocampal volume, there is substantial residual
variation (differences of up to 25%) in the size of hippocampal regions,
cell layers, and numbers of neurons. This variation is generated by unknown
gene variants. In this study we mapped new QTLs to chromosome (Chr) 6, 13,
and 15 (genome-wide P <0.05, R<sup>2</sup> = 0.2—0.4). HipV15a on Chr 15
controls volume of the hippocampus proper (LRS of 22.6, 2-LOD CI 0—10 cM).
In contrast, DGV13a on Chr 13 controls the volume of the dentate gyrus (LRS
of 20.2, 2-LOD CI 25—35 cM). GrV6a on Chr 6 controls the volume of the
granule cell layer and the total number of granule cells (LRS 16.4, 2-LOD CI
16—25 cM). PyV1a on Chr 1 controls the volume of the pyramidal cell layer (LRS
18.3, 2-LOD CI 70—80 cM) and overlaps the Hipp1a locus. These new QTLs may
colocalize with QTLs and candidate genes that control differences in cell
proliferation in hippocampus and perhaps in behavioral capacity. (Our thanks
to Dr. Glenn D. Rosen for MBL resource development.) Key Words: NEUROGENSIS, QUANTITATIVE TRAIT LOCI, NEUROGENETICS, GRANULE
CELL Since 20 April 2001
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Neurogenetics at University of Tennessee Health Science Center
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