Comparison of the Genomic Sequence of the Microminipig, a Novel Breed of Swine, with the Genomic Database for Conventional Pig

The microminipig, which weighs less than 10 kg at an early stage of maturity, has been reported as a potential experimental model animal. Its extremely small size and other distinct characteristics suggest the possibility of a number of differences between the genome of the microminipig and that of conventional pigs. In this study, we analyzed the genomes of two healthy microminipigs using a next-generation sequencer SOLiDTM system. We then compared the obtained genomic sequences with a genomic database for the domestic pig (Sus scrofa). The mapping coverage of sequenced tag from the microminipig to conventional pig genomic sequences was greater than 96% and we detected no clear, substantial genomic variance from these data. The results may indicate that the distinct characteristics of the microminipig derive from small-scale alterations in the genome, such as Single Nucleotide Polymorphisms or translational modifications, rather than large-scale deletion or insertion polymorphisms. Further investigation of the entire genomic sequence of the microminipig with methods enabling deeper coverage is required to elucidate the genetic basis of its distinct phenotypic traits. Swine provide very reliable experimental animal models because of their physiological and anatomical similarities to humans (1). The number of pigs utilized as laboratory swine every year in the European Union alone exceeds 60,000 (2, 3). The microminipig (Fuji Micra Inc., Shizuoka, Japan; brand name registered with the Japanese Ministry of Agriculture, Forestry and Fisheries) is a novel breed of swine which has emerged as a possible experimental model animal for non-clinical pharmacological/toxicological use (1, 4-15). The common maternal ancestor, or “Eve”, of the microminipig is a sow named “Catherine”, bred by mating a pot-bellied pig and another type of minipig (5). Young, mature microminipigs weigh less than 10 kg, which enables easy handling (8-10, 14). The levels of the major hematological and biochemical parameters in microminipigs have been reported as being generally similar to those in Gottingen and Yucatan minipigs (16, 17). However, the coagulatory activity, prothrombin time and activated partial thromboplastin time in microminipigs differ from those in Gottingen and Yucatan minipigs (9). The microminipig has also been reported as a suitable model for arthrosclerosis and associated pathological investigations. The microminipig resembles humans in its sensitivity to a high fat diet, and the subsequent development of atherosclerotic vascular lesions and a cholesterol-related metabolic cascade (6). The atherosclerotic lesions in microminipigs more closely resemble those in humans than do any other breed of swine. In the present study, we analyzed the genomes of two healthy microminipigs and compared them to a reference genome for conventional pigs (Sus scrofa). 1107 *These Authors contributed equally to this study. Correspondence to: Hiroaki Kawaguchi, Department of Veterinary Histopathology, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan. Tel: +81 992858720, Fax: +81 992858722, e-mail: k3038952@kadai.jp and Akihide Tanimoto, Department of Molecular and Cellular Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1, Sakuragaoka, Kagoshima 890-8544, Japan. Tel: +81 992755263, Fax: +81 992646348, e-mail: akit09@m3.kufm. kagoshima-u.ac.jp