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This study characterized autochthonous pig breeds of Vietnam and compared them with breeds from other regions. A total of 343 animals were considered from 5 indigenous pig breeds of Vietnam (Muong Khuong, Co, Meo, Tap Na, and Mong Cai), 2 exotic breeds kept in Vietnam (Landrace and Yorkshire), 3 European commercial breeds (German Landrace, Pietrain, and Large White), the Chinese breed Meishan, and the European Wild Boar. Each individual was genotyped for 20 selected polymorphic microsatellite loci. The Vietnamese autochthonous breeds showed higher degrees of polymorphism, allelic diversity, and heterozygosity than the other pig breeds. Also, large genetic diversity was observed across the area of distribution, with village-specific subpopulations, which led to significant inbreeding coefficients. As expected, genetic distances showed large differences among European-based, Chinese, and Vietnamese indigenous breeds and reflected the geographical distribution of breeds. In comparison with the European breeds, the Vietnamese indigenous pig breeds harbored a considerable amount of genetic diversity and, therefore, will be of significance for livestock bioconservation. Key words: genetic distance, genetic diversity, microsatellite, pig breed

A QTL analysis of multibreed experiments (i.e., crossed populations involving more than two founder breeds) offers clear advantages over classical two-breed crosses, among them increased power and a more comprehensive coverage of the total genetic variability in the species. An alternative to designed multibreed crosses is to reanalyze jointly several experiments involving different breeds. We report a multibreed, multitrait QTL analysis of SSCX that involves five different crosses, six breeds, and almost 3,000 genotyped individuals using a truly multibreed strategy to allow for any number of founder breed origins. Traits analyzed were growth, fat thickness, car-cass length, and shoulder and ham weights. Generally, the joint analysis resulted in more significant QTL than the single-experiment analyses. We show that the QTL for fatness, which is highly significant (nominal P < [10.sup.-43]), is of Asiatic origin (Meishan). The next most significant QTL (nominal P < [10.sup.15]) affected ham weight and seems to be segregating only between Large White and the rest of the breeds. A multitrait, multi-QTL analysis suggests that these are two distinct loci. Additionally, a locus segregating only between Iberian and Landrace affects live weight. The advantages of joint, multibreed analyses clearly outweigh their potential risks. Key Words: Fatness, Growth, Pig, Quantitative Trait Locus, Sex Chromosome

Quantitative trait loci (QTL) for fat deposition, growth and muscling traits have been previously mapped on the basis of low-density linkage maps in a wild boar × Meishan F2 family to the chromosome X region flanked by SW2456 and SW1943. Improved QTL resolution was possible using data for F2 animals with a marker density of 2.7 cM distance in the SW2456 to SW1943 region, including AR, SERPINA7 and ACSL4 as candidate genes. The resolution of the QTL scan was increased substantially, as evidenced by the higher F-ratio values for all QTL. Maxima of F-ratio values for fat deposition, muscling and growth traits were 28.6, 18.2 and 16.5 respectively, and those QTL positions accounted for 7.9%, 5.0% and 4.5% of the F2 phenotypic variance (VF2) respectively. QTL for fatness and growth and for most muscling traits mapped near ACSL4, with the exception of the QTL for ham traits that mapped proximally, in the vicinity of AR. An analysis performed separately for F2 male animals showed the predominant QTL affecting fat deposition traits (up to 13.6% VF2) near AR and two QTL for muscling traits (up to 9.9% VF2) mapped close to ACSL4. In the F2 female animals, QTL affecting muscling (up to 12.1% VF2) mapped at ACSL4 and SW2456, and QTL for fat deposition (10% VF2) and growth (up to 10.5% VF2) mapped at ACSL4. [ABSTRACT FROM AUTHOR]

The lamins are components of nuclear lamina and they have a profound influence on nuclear structure and functions. They are encoded by three genes, LMNA, LMNB1 and LMNB2. A genomic fragment of the porcine LMNA gene (822 bp; from exons 7 to 9) was amplified by polymerase chain reaction and comparatively sequenced. Four single nucleotide polymorphisms (SNPs) were identified in intronic sequences: G162 A, G208 A, T367 G and C618 T. The SNPs are within the restriction sites for enzymes Bsh1236I, HpaII, AluI and Bsh1236I respectively. Allele frequencies at SNPs G208 A, T367 G and C618 T were determined by using eight pig breeds. Linkage analysis in the Hohenheim Meishan × Piétrain family placed the LMNA gene in the chromosome 4q linkage group, between MEF2D and GBA ( MEF2D– 3.0 cM – LMNA– 0.2 cM – GBA). In radiation hybrid mapping LMNA was most significantly linked to SW270 on chromosome 4 (39 cR; LOD = 7.86). The LMNA gene is located in the quantitative trait loci region for some carcass traits on chromosome 4q. [ABSTRACT FROM AUTHOR]

Polymorphic microsatellite and open-reading frame (ORF) sites in the prion protein coding gene (PRNP) were analysed in eight sheep breeds. The three microsatellite sitesS11,S15andS24were genotyped by fragment length analysis, and the ORF codons 136, 154 and 171 were analysed after direct sequencing. Unexpected polymerase chain reaction (PCR) products of microsatellite sites and ORF haplotypes with more than one heterozygous site were submitted to cloning and then sequenced. The microsatellite sites were polymorphic in all breeds with two to five alleles per site. On average of breeds and sites, the microsatellites had higher degrees of polymorphism than the ORF sites. TheARR/ARRORF genotype occurred always together with the microsatellite genotypesS11152/152,S15179/179 andS24144/144. As ORF and microsatellite alleles of thePRNPwere observed in typical combinations, the microsatellite genotypes were significantly associated with scrapie incidences or risk classes based on the ORF genotypes. The microsatellite sites were highly polymorphic and therefore are advantageous markers for evaluation of scrapie disposition and fine mapping of effects on scrapie pathogenesis within the gene. [ABSTRACT FROM AUTHOR]

Three informative pig F2 families based on European Wild Boar (W), Meishan (M) and Pietrain (P) crosses have been used for genome-wide linkage and quantitative trait loci (QTL) analysis. Altogether 129 microsatellites, 56 type I loci and 46 trait definitions (specific to growth, fattening, fat deposition, muscling, meat quality, stress resistance and body conformation) were included in the study. In the linkage maps of M × P, W × P and W × M families, average spacing of markers were 18.4, 19.7 and 18.8 cM, the numbers of informative meioses were 582, 534 and 625, and the total lengths of autosomes measured were 27.3, 26.0 and 26.2 Morgan units, respectively. Maternal maps were on average 1.3 times longer than paternal maps. QTLs contributing more than 3% of F2 phenotypic variance could be identified at p < 0.05 chromosome-wide level. Differences in the numbers and positions of QTLs were observed between families. Genome-wide significant QTL effects were mapped for growth and fattening traits on eight chromosomes (1, 2, 4, 13, 14, 17, 18 and X), for fat deposition traits on seven chromosomes (1, 2, 3, 4, 6, 7 and X), for muscling traits on 11 chromosomes (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 and X), for meat quality and stress resistance traits on seven chromosomes (2, 3, 6, 13, 16, 18 and X), and QTLs for body-conformation traits were detected on 14 chromosomes. Closely correlated traits showed similar QTL profiles within families. Major QTL effects for meat quality and stress resistance traits were found on SSC6 in the interval RYR1-A1BG in the W × P and M × P families, and could be attributed to segregation of the RYR1 allele T derived from Pietrain, whereas no effect in the corresponding SSC6 interval was found in family W × M, where Wild Boar and Meishan both contributed the RYR1 allele C. QTL positions were mostly similar in two of the three families for body conformation traits and for growth, fattening, fat deposition and muscling traits, especially on SSC4 (interval SW1073-NGFB). QTLs with large effects were also mapped on SSC7 in the major histocompatibility complex (MHC) (interval CYP21A2-S0102) and affected body length, weight of head and many other traits. The identification of DNA variants in genes causative for the QTLs requires further fine mapping of QTL intervals and a positional cloning. However, for these subsequent steps, the genome-wide QTL mapping in F2 families represents an essential starting point and is therefore significant for animal breeding. [ABSTRACT FROM AUTHOR]

Linkage and QTL maps of Sus scrofa chromosome 17 (SSC17) were analysed with five markers and in three F2 families basedon Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The maps were similar across the three families and agree well with published maps. In the M × P family, new quantitative trait loci (QTLs) for growth and fat deposition were locatedin the vicinity of GHRH, whereas in the W × P family one minor QTLs for daily gain was detected. No QTL was found in the W x M family. [ABSTRACT FROM AUTHOR]