Molecular Ecology Notes (2005) 5, 851–853 doi: 10.1111/j.1471-8286.2005.01086.x © 2005 Blackwell Publishing Ltd Blackwell Publishing, Ltd. PRIMER NOTE Characterization of six microsatellite DNA loci for Sorex arizonae J. ORTEGA,*‡ S. YOUNG,*§ L. H. SIMONS† and J. E. MALDONADO* *Genetics Laboratory, National Museum of Natural History, Smithsonian Institution, 3001 Connecticut Ave. N.W., Washington DC, 20008, USA, † USDA Forest Service, Shasta-Trinity National Recreation Area, 14225 Holiday Road, Redding, CA 96003 USA Abstract Sorex arizonae is a rare species that occupies a narrow range of habitat types in several mountain ranges of New Mexico, Arizona and Northern Mexico. Here we identify and char- acterize six microsatellite loci for this species. We screened 63 individuals from four differ- ent localities from New Mexico and Arizona to analyse genetic variability. Alleles ranged from three to 16. Heterozygosity ranged from 40% to 78%. Most polymorphic loci were in Hardy–Weinberg equilibrium with the exception of one locus. Primers appear to have rea- sonable cross-species applicability as five loci amplified in another shrew species ( Sorex monticolus). Keywords: Heterozygosity, microsatellites, polymorphic loci, rare species, Sorex arizonae Received 25 April 2005; revision accepted 20 May 2005 The Arizona shrew (Sorex arizonae) is one of the most restricted shrews in North America. The species has a disjunctive montane distribution in southern Arizona and New Mexico, and the Sierra Madre Occidental of Chihuahua, Mexico (Simons & Hoffmeister 2003). Currently, the Arizona shrew is listed by the Mexican and the US governments as endangered and species of special concern, respectively (Arita & Ceballos 1997). Microsatellites have been isolated and characterized for different shrews such as S. araneus (16), Sorex caecutiens (3) and Sorex unguiculatus (3), which are all Old World species (Wyttenbach et al . 1997; Balloux et al . 1998; Naitoh et al . 2002). However, specific microsatellites for North American species are not available in GenBank, and they would seem particularly valuable to assess gene flow, genetic variabil- ity and conservation status for this threatened species. In this paper, we developed microsatellite markers for S. arizonae , which were tested for polymorphism on four of the five mountain ranges where this species is known to occur. DNA was isolated from tissue samples of S. arizonae using the DNeasy Tissue Kit (QIAGEN). Microsatellite loci were isolated following the standard protocol of Hamilton et al . (1999). Restriction enzymes Nhe I, Rsa I, Hae III and Xmn I (New England Biolabs) were used to digest genomic DNA. Double-stranded ‘SNX’ linkers were used to amplify the genomic DNA. The ligation was denatured and an AC- repeat-enriched library was obtained by hybridizing to a 5 ′ biotinylated oligo. Hybridized DNA was mixed with magnetic beads (Dynabeads) and incubated for 3 h at 43 ° C. DNA was recovered from the beads by denaturation and made double-stranded by polymerase chain reaction (PCR) using the SNX-forward linker as a primer. PCR products were digested overnight with Nhe I (New Eng- land Biolabs). Enriched genomic libraries were cloned into Xba I digested P-bluescript SK+ (Stratagene), and resultant plasmids were transformed into Escherichia coli Supercom- petent Cells (Stratagene). Positive colonies were picked and lysed with heat for 10 min at 100 ° C in 200 μ L TE [10 m m Tris-HCl, 0.1 m m EDTA (pH 8.0)]. PCR amplifications of the lysed colonies were sub- sequently conducted and these contained a total volume of 25 μ L: 50 –100 ng of DNA, ddH 2 O, 0.1 U of AmpliTaq® DNA polymerase (Applied Biosystems), 10 μm of both primers (T7 and T3), 25 mm of MgCl 2 , 10× PCR Buffer II Correspondence: J. Ortega, E-mail: artibeus2@aol.com ‡Present address: Laboratorio de Macroecología, Departamento de Ecología de la Biodiversidad, Instituto de Ecología, UNAM, Circuito Exterior junto a Jardín Botánico, Ciudad Universitaria, Apdo. Postal 70 –275, México City, D. F., 04510, México. §Present address: Department of History, International and Social Studies, Aalborg University, Fibigerstræde 2, DK-9220 Aalborg, Øst, Denmark.