Genetic and physical mapping of the fitness 1 (fit1) locus within the Fes-Hbb region of mouse Chromosome 7

Abstract

Mutations at the fit1 locus affect normal pre- and post-natal development by retarding growth and reducing viability. We report mapping of the fit1 locus, by trans-complementation crosses to mice carrying deletions of the albino (c) locus in Chromosome (Chr) 7, to a subregion of the c-deletion complex within the Mod2-sh1 interval. The fit1 locus, which is currently defined by five N-ethyl-N-nitrosourea (ENU)-induced mutations, was found to map in a subregion between the eed and exed loci. A restriction fragment containing a deletion breakpoint that genetically defines the proximal border of fit1 was cloned, providing a DNA probe (RN302) that maps proximal to fit1. Long-range mapping with this probe, and with a DNA probe that maps distal to the fit1 interval, established that the region containing at least part of the fit1 gene is 530 kb or less. Positioning of fit1 between deletion breakpoints, and the isolation and mapping of a DNA probe proximal to it, should facilitate the cloning and molecular characterization of fit1, as well as of the eed locus and the tightly linked l(7)5Rn and l(7)6Rn loci.

Role of the clathrin adaptor PICALM in normal hematopoiesis and polycythemia vera pathophysiology

“…[34][35][36] Studies of Fit1 mutants, although useful, do not represent an ideal model for understanding the role of PICALM, because they are heterozygous for a Picalm point mutation and harbor the Del 26DVT deletion in the other allele, removing a 11cM segment including the Picalm gene. [34][35][36] Suzuki and colleagues recently reported a conventional Picalm knockout strain. 37 They reported that more than 90% of Picalm -/-newborn pups die before weaning and body weights of surviving Picalm -/-mice are significantly lower than those of controls.…”

Mutations in the clathrin-assembly gene Picalm are responsible for the hematopoietic and iron metabolism abnormalities in fit1 mice

“…The origin and initial maintenance of mouse strains carrying the fit1 4R and fit1 5R mutations, as well as the generation of mice hemizygous for the fit1 alleles [i.e., Tyr c fit1͞Del(Tyr fit1) 26DVT , hereafter referred to as fit1͞Del 26DVT ], have been described previously (2,8,15,16). Tyr c-ch ϩ͞Del 26DVT mice are phenotypically normal (2).…”

“…BAC clone RPCI-23-68G17, derived from a C57BL͞6J library (17), was purchased from ResGen͞Invitrogen; BAC DNA was isolated for analysis according to the manufacturer's instructions. SSLP markers D7Mit32, D7Mit352, and D7Mit300; STS markers M-09035 and M-02716; and markers for the D7Cwr11D, D7Mlk1 and D7Mlk2 loci, all of which map within the deletions and yeast artificial chromosome (YAC) contigs spanning the fit1 interval (15,18,19), were mapped against the BAC by PCR analyses, by using specific primers. SSLP primers were purchased from ResGen͞Invitrogen, and the sequences of all other primers used in this study are available (Table 1, which is published as supporting information on the PNAS web site, www.pnas.org).…”

N -Ethyl- N -Nitrosourea Mutagenesis: Boarding the Mouse Mutant Express

“…In this scheme, coat color alleles of various severity for albino (c) or pink-eyed dilute (p) were used to distinguish between chromosomes contributed by different parents and, thus, to allow identification of progeny carrying new mutations in the interval of interest (43,46). In this manner, embryonic lethal, developmental mutations, such as eed and fit-1, were first recovered (39,44). In the example shown in Fig.…”