Genetic mapping of the human and mouse phospholipase C genes

To determine chromosome positions for 10 mouse phospholipase C (PLC) genes, we typed the progeny of two sets of genetic crosses for inheritance of restriction enzyme polymorphisms of each PLC. Four mouse chromosomes, Chr 1, 11, 12, and 19, contained single PLC genes. Four PLC loci, Plcb1, Plcb2, Plcb4, and Plcg1, mapped to three sites on distal mouse Chr 2. Two PLC genes, Plcd1 and Plcg2, mapped to distinct sites on Chr 8. We mapped the human homologs of eight of these genes to six chromosomes by analysis of human × rodent somatic cell hybrids. The map locations of seven of these genes were consistent with previously defined regions of conserved synteny; Plcd1 defines a new region of homology between human Chr 3 and mouse Chr 8. Received: 24 January 1996 / Accepted: 2 April 1996     

Neonatal mortality and leanness in mice lacking the ARID transcription factor Mrf-2

Proteins containing the ARID (AT-rich interaction domain) DNA-binding motif regulate gene expression and differentiation in fungi, plants, and animals. This report describes phenotypes resulting from targeted disruption of the ARID gene Mrf-2. Homozygous loss of Mrf-2 resulted in a high rate of neonatal mortality that was partially strain-dependent: survival of Mrf-2(-/-) pups ranged from 6.4% on the 129S1 genetic background to 38% on a mixed 129S1.C57Bl/6J background. Loss of Mrf-2 expression did not affect embryonic survival, embryonic growth or birth weight. Lipid accumulation was severely reduced in brown adipose of Mrf-2(-/-) neonates at 24h of age, however, and Mrf-2(-/-) mice weighed significantly less than controls from postnatal day five onward. Adult Mrf-2(-/-) mice were lean, with significant reductions in brown and white adipose tissues, and in the percentage of body fat. Mrf-2(-/-) and Mrf-2(+/-) mice were also resistant to weight gains and obesity when maintained on high-fat diets. These phenotypes suggest that Mrf-2 is essential for accumulation of lipid stores in postnatal life.     

Additional mapping of mouse chromosome 2 genes

The purpose of this work was to elucidate the genetic fine structure of the central portion of mouse chromosome (Chr) 2. Seven Chr 2 congenic mouse strains [B10.PA(L)-pa we un a ^t , B10.PA(L)-pa A ^w , B10.PA(L)-we un a ^t , B10.PA(J)-pa a, B10.FS-we A ^w , B10.C-we A ^w , and B10.YBR-a] were produced. Breeding studies were carried out using strains B10.PA(L)-pa we un a ^t and B10.LP-H-13 ^b to accurately determine the recombination frequencies between marker genes pa and we (1.9%±0.3), we and un (8.8%±0.5), and un and a ^t (4.5%±0.4) of strain B10.PA(L)-pa we un a ^t . These strains and other Chr 2 congenic strains were typed for immunologically defined loci using monoclonal antibody (mAb) C23 reactive with the gene product of B2m ^b T-lymphocyte clone C1 reactive with the gene product of H-3 ^a and H-3 ^c , and lymphocyte clone H1.8 reactive with the gene product of Hd-1 ^a . B2m and H-3 typing located a recombinational event separating [pa B2m H-3] from we (the order of bracketed genes is not known). Hd-1 typing indicated that Hd-1 maps distal to [H-42, H-44] and proximal to un. The gene order [pa, B2m, H-3], we, [H-42, H-45], Hd-1, un, H-13, a ^t , with H-44 mapping centromeric to Hd-1, is indicated by the data. Address correspondence and offprint requests to: R. J. Graff.     

Genetic mapping of the mouse interleukin 3 gene to chromosome 11

Interleukin 3 (IL 3) is a T cell-derived lymphokine that induces the proliferation and differentiation of early hematopoietic stem cells. By using a cDNA clone for IL 3, a single Eco-RI restriction fragment of 8.5 kbp was detected in Southern blot hybridizations of DNA from BALB/c and C57BL/10 mice, whereas an Eco-RI restriction fragment of 10.8 kbp was detected in NFS and A/J mice. Under the conditions used, no hybridization was detected to Chinese hamster DNA. The species and strain differences were used to analyze a series of hamster X mouse somatic cell hybrids and genetic crosses between NFS and C57BL/10 mice. The results demonstrate that the IL 3 gene is located on chromosome 11.