Experiment
Linkage analysis was performed on (C57BL/6J x PWK/PhJ)F2 animals to identify genetic loci associated with preference and intake of calcium and other salt compounds. Animals were subjected to a two-bottle choice test between water and one other solution (CaCl2, CaLa, MgCl2, KCl, NH4Cl, NaCl, citric acid, QHCl, or saccharin) for a period of 96 hours. PWK/PhJ is a high consumer of calcium chloride (CaCl2) and calcium lactate (CaLa) whereas C57BL/6J is a relatively low consumer. PWK/PhJ also consumes more MgCl2 compared to C57BL/6J. However, when consumption of KCl, NaCl and saccharin were analyzed, C57BL/6J animals consumed more of these solutions compared to PWK/PhJ animals. Linkage analysis was performed using 116 polymorphic markers at a resolution of 10cM - 30cM. Thirty QTLs reaching statistical significance were identified. Authors assigned separate QTL nomenclature for each of the salt compound QTL even if they mapped to the same linkage marker.
On mouse Chromosome 1, linkage to saccharin intake mappedto 15 cM (24 Mb) near D1Mit169 (LOD=3.4). This locus explains 3.1% of the phenotypic variance and is named Drinksac5 (drink saccharin 5). C57BL/6J-derived alleles at Drinksac5 confer increased saccharin solution intake. Significant linkage to CaCl2 intake and preference mapped to 104 Mb near D1Mit1001 (LOD=3.8 and 4.3, respectively). This locus is named Drinkcacl24 (drink calcium chloride 2 4). PWK/PhJ-derived alleles at Drinkcacl24 confer increased CaCl2 intake and preference with dominant inheritance. Drinkcacl24 explains 3.9% of the variance in CaCl2 intake and 4.4% of the CaCl2 preference variance. Significant linkage to MgCl2 intake also mapped to the same locus and is named Drinkmgcl24 (drink magnesium chloride 2 4). PWK/PhJ-derived alleles at Drinkmgcl24 confer increased Mgcl2 preference with a dominant mode of inheritance. Drinkmgcl24 explains 3.6% of the variance in MgCl2 preference.
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