Gene Mapping Report Cytogenet Cell Genet 93:141–142 (2001) Assignment 1 of the fatty acid synthase (FASN) gene to bovine chromosome 19 (19q22) by in situ hybridization and confirmation by somatic cell hybrid mapping R. Roy, a M. Gautier, b H. Hayes, b P. Laurent, b R. Osta, a P. Zaragoza, a A. Eggen, b and C. Rodellar a a Laboratorio de Genética Bioquı ´mica y Grupos Sanguı ´neos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza (Spain); b Laboratoire de Génétique biochimique et de Cytogénétique, INRA-CRJ, Jouy-en-Josas (France) 1 To our knowledge this is the first time this gene has been mapped in cattle. R. R. was supported by a doctoral grant from the M.E.C. Received 19 December 2000; manuscript accepted 20 February 2001. Request reprints from Rosa Roy, Laboratorio de Genética Bioquı ´mica, Facultad de veterinaria, c/ Miguel Servet, 50013 Zaragoza (Spain); telephone: 34976761620; fax: 34976761612; email: 118228@vetez.unizar.es ABC Fax + 41 61 306 12 34 E-mail karger@karger.ch www.karger.com © 2001 S. Karger AG, Basel 0301–0171/01/0932–0141$17.50/0 Accessible online at: www.karger.com/journals/ccg Rationale and significance Fatty acid synthase (FASN) plays a central role in de novo lipogenesis in mammals. With seven active sites, FASN cata- lyzes all the reaction steps in the synthesis of palmitate from acetyl-CoA and malonyl-CoA in the presence of NADPH. In animals the synthesis of FASN is a regulated process which depends on diet and hormones at all stages of life, even during neonatal development and differentiation. The FASN gene has been cloned and sequenced in several species such as rat (M84761), chicken (J04485), mouse (X13135) and human (NM004104). Whereas, the bovine FASN gene remains unas- signed, human FASN has been located on chromosome 17q25 (Jayakumar et al. 1994). We report the localization of the bovine FASN gene on bovine (BTA) chromosome 19q22 by fluorescence in situ hybridization and somatic cell hybrid anal- ysis. Materials and methods Isolation of a bovine specific FASN fragment Two primers designed from the rat FASN sequence (GenBank accession number: M84761) were used to amplify a 180-bp fragment of the bovine FASN gene: FASN1: 5)-ATCTTCTTGAAGAACGTGAC-3) FASN2: 5)-CATGTATCGGAAGGCGTCCT-3) PCR amplification was performed using 20 ng of genomic DNA. Cycling conditions were 94 ° C for 30 s, 55 ° C for 30 s and 72 ° C for 30 s for 30 cycles. PCR products were cloned and sequenced. Homology searches were per- formed with BLAST programs at National Center for Biotechnology Infor- mation (http://www.ncbi.nlm.nih.gov/BLAST/). The isolated bovine sequence showed a high degree of similarity with FASN sequences from other species, and with rat FASN exon 32 (Amy et al., 1992). Screening of BAC library The above primers were used to screen a bovine BAC library (Eggen et al., in preparation). Two BAC clones containing the bovine FASN gene were identified. Insert sizes were determined by Field Inversed Gel Electrophore- sis (FIGE): BAC 439G6, 50 kb and BAC 817E11, 100 kb. Fluorescence in situ hybridization (FISH) In situ hybridization was performed on RBP-banded bovine chromo- some preparations (Hayes et al. 2000). Probe name: 439G6BAC Probe type: genomic DNA Vector: pBeloBAC11 Insert size: 50 kb Proof of authenticity: DNA sequencing. Gene reference: AF285607 Somatic cell hybrid mapping Somatic cell hybrid analysis was performed using a panel of 38 hamster- bovine hybrid clones constructed by Heuertz and Horst-Cayla (1981) and characterized by Laurent et al. (2000). Primers FASN1 and FASN2 were used to amplify a 180-bp fragment from the FASN bovine sequence.