Berlin Miniature Pig Research Articles

Genetic Association of the Porcine C9 Complement Component with Hemolytic Complement Activity.

The complement system is a part of the natural immune regulation mechanism against invading pathogens. Complement activation from three different pathways (classical, lectin, and alternative) leads to the formation of C5-convertase, an enzyme for cleavage of C5 into C5a and C5b, followed by C6, C7, C8, and C9 in membrane attack complex. The C9 is the last complement component of the terminal lytic pathway, which plays an important role in lysis of the target cells depending on its self-polymerization to form transmembrane channels. To address the association of C9 with traits related to disease resistance, the complete porcine C9 cDNA was comparatively sequenced to detect single nucleotide polymorphisms (SNPs) in pigs of the breeds Hampshire (HS), Duroc (DU), Berlin miniature pig (BMP), German Landrace (LR), Pietrain (PIE), and Muong Khuong (Vietnamese potbelly pig). Genotyping was performed in 417 F2 animals of a resource population (DUMI: DU×BMP) that were vaccinated with Mycoplasma hyopneumoniae, Aujeszky diseases virus and porcine respiratory and reproductive syndrome virus at 6, 14 and 16 weeks of age, respectively. Two SNPs were detected within the third exon. One of them has an amino acid substitution. The European porcine breeds (LR and PIE) show higher allele frequency of these SNPs than Vietnamese porcine breed (MK). Association of the substitution SNP with hemolytic complement activity indicated statistically significant differences between genotypes in the classical pathway but not in the alternative pathway. The interactions between eight time points of measurement of complement activity before and after vaccinations and genotypes were significantly different. The difference in hemolytic complement activity in the both pathways depends on genotype, kind of vaccine, age and the interaction to the other complement components. These results promote the porcine C9 (pC9) as a candidate gene to improve general animal health in the future.

Detection of a polymorphic site of the porcine <i>C8G</i> gene and evaluation of association with haemolytic complement activity

Abstract. C8 is a component of the membrane attack complex (MAC) of the complement system, which causes lysis of the target cells. C8 consists of three subunits C8A, C8B, and C8G. This study focus on the porcine C8G gene aiming to identify its cDNA sequence, to detect single nucleotide polymorphism (SNP), and to analyse its association with haemolytic complement activity in the classical (CH50) and the alternative (AH50) pathway. The C8G is 840 bp in length encoding 202 amino acids. The C8G is similar (≥65 %) among mammalian species (pig, human, cattle, dog, and mouse) at both the cDNA and the protein level. One SNP was detected at nucleotide 423C→T (SNP c.423C>T; codon 124GAC→GAT). The SNP does not segregate among the European commercial breeds German Landrace and Pietrain but in the Vietnamese autochthonous breed Muong Khuong (Vietnamese potbelly pig) and an experimental F2 crossbreed population based on Duroc and Berlin Miniature Pig (DUMI). Haemolytic complement activity of animals of the DUMI populations obtained at about 6, 14 and 16 weeks of age before and after vaccinations showed short-termed increments due to the immune stimulation and long-term increase due to aging. Family based association tests indicate effects of C8G on AH50 and CH50 at 16 weeks of age immediately before PRRS vaccination (AH50_PRRS0, P=0.087; CH50_PRRS0, P=0.027). However, the results did not indicate a consistent effect of the respective alleles on haemolytic complement activity in the alternative and the classical pathway. The study provides weak evidence for the candidacy of the porcine C8G for innate immune response and disease resistance in pigs.

Polymorphic sites in the 5´-region of the porcine <i>C8A</i> gene

Abstract. The membrane attack complex (MAC) of the complement system is known as a natural immune mechanism of hosts against invading pathogens. This study was undertaken to structurally characterize and computationally analyzed the 5´-region, i.e. the downstream promoter region and the 5´-UTR nucleotide sequence of the porcine C8A, one of the components of the MAC. Sequencing approximately 950 bp of the 5´-region and analyzing in silico revealed the transcription start site, the TATA-box, the CAAAT-box, and the GATAAbox. High identity was found in range of 37–74 % among the sequences of pig, human, cattle, and mouse. Transcription factor binding sites, such as NFκB, Oct-1, HNF1, CDP, and C/EBP, showed high conservation between vertebrate animal species, especially between human and mouse, or pig and cattle. Seven single nucleotide polymorphisms were detected in the breeds Hampshire, Duroc, German Landrace, Large White, Pietrain, Berlin Miniature Pig, and Muong Khuong. Nucleotide exchanges could cause the generation of new binding motifs, which may affect the expression of the porcine C8A, particularly the C/EBP regulation of the porcine C8A gene – as described in the human C6 and C7 promoter.

The three-way relationship of polymorphisms of porcine genes encoding terminal complement components, their differential expression, and health-related phenotypes

BackgroundThe complement system is an evolutionary ancient mechanism that plays an essential role in innate immunity and contributes to the acquired immune response. Three modes of activation, known as classical, alternative and lectin pathway, lead to the initiation of a common terminal lytic pathway. The terminal complement components (TCCs: C6, C7, C8A, C8B, and C9) are encoded by the genes C6, C7, C8A, C8B, C8G, and C9. We aimed at experimentally testing the porcine genes encoding TCCs as candidate genes for immune competence and disease resistance by addressing the three-way relationship of genotype, health related phenotype, and mRNA expression.ResultsComparative sequencing of cDNAs of animals of the breeds German Landrace, Piétrain, Hampshire, Duroc, Vietnamese Potbelly Pig, and Berlin Miniature Pig (BMP) revealed 30 SNPs (21 in protein domains, 12 with AA exchange). The promoter regions (each ~1.5 kb upstream the transcription start sites) of C6, C7, C8A, C8G, and C9 exhibited 29 SNPs. Significant effects of the TCC encoding genes on hemolytic complement activity were shown in a cross of Duroc and BMP after vaccination against Mycoplasma hyopneumoniae, Aujeszky disease virus and PRRSV by analysis of variance using repeated measures mixed models. Family based association tests (FBAT) confirmed the associations. The promoter SNPs were associated with the relative abundance of TCC transcripts obtained by real time RT-PCR of 311 liver samples of commercial slaughter pigs. Complement gene expression showed significant relationship with the prevalence of acute and chronic lung lesions.ConclusionsThe analyses point to considerable variation of the porcine TCC genes and promote the genes as candidate genes for disease resistance.

Association of parathyroid hormone‐like hormone (PTHLH) and its receptor (PTHR1) with the number of functional and inverted teats in pigs

Parathyroid hormone-like hormone gene (PTHLH) and its receptor, parathyroid hormone/ parathyroid hormone-like hormone receptor 1 (PTHR1), play a role in epithelial mesenchymal interactions during growth and differentiation of different tissues and anatomic structures, including teats. Therefore, PTHLH and PTHR1 were evaluated as functional candidate genes for their effects on number and shape of teats in pigs. In particular, focus was on the occurrence and number of inverted teats, the most frequent and economically relevant teat developmental defect in pigs. For this purpose, association and linkage of the PTHLH gene and the PTHR1 gene with inverted teat defect and the total number of teats and inverted teats were studied in an experimental Duroc and Berlin Miniature pig (DUMI) population. Polymorphism C1819T of PTHR1 was significantly associated with inverted teat phenotype (p = 0.014), total number of teats (p = 0.047) and was close to significance with the number of inverted teats (p = 0.078). Polymorphism C375T of PTHLH was close to significance with the inverted teat phenotype (p = 0.122) and showed no significant association with the total number of teats (p = 0.621) and the number of inverted teats (p = 0.256) in the DUMI population. Association analyses were also performed for combined effects of PTHLH and PTHR1 in order to address potential interaction, however, revealed no indication of effects of interaction. The function, position and the association shown here promote PTHR1 as a candidate gene for number of teats and in particular for affection by and number of inverted teats.

QTL for the heritable inverted teat defect in pigs

The mothering ability of a sow largely depends on the shape and function of the mammary gland. The aim of this study was to identify QTL for the heritable inverted teat defect, a condition characterized by disturbed development of functional teats. A QTL analysis was conducted in a porcine experimental population based on Duroc and Berlin Miniature pigs (DUMI). The significant QTL were confirmed by linkage analysis in commercial pigs according to the affected sib pair design and refined by family-based association test (FBAT). Nonparametric linkage (NPL) analysis revealed five significant and seven suggestive QTL for the inverted teat defect in the porcine experimental population. In commercial dam lines five significant NPL values were detected. QTL regions in overlapping marker intervals or close proximity in both populations were found on SSC3, SSC4, SSC6, and SSC11. SSC6 revealed QTL in both populations at different positions, indicating the segregation of at least two QTL. The results confirm the previously proposed polygenic inheritance of the inverted teat defect and, for the first time, point to genomic regions harboring relevant genes. The investigation revealed variation of the importance of QTL in the various populations due to either differences in allele frequencies and statistical power or differences in the genetic background that modulates the impact of the liability loci on the expression of the disease. The QTL study enabled us to name a number of plausible positional candidate genes. The correspondence of QTL regions for the inverted teat defect and previously mapped QTL for teat number are in line with the etiologic relationship of these traits.

Porcine IL12A and IL12B gene mapping, variation and evidence of association with lytic complement and blood leucocyte proliferation traits

Interleukin-12, a heterodimeric cytokine consisting of glycosylated subunits of 35 and 40 kDa, is a central molecule in controlling innate as well as adaptive immunity. This study was aimed to investigate the role of IL12A and IL12B as candidate genes for immune competence in pigs. The porcine genes were screened for polymorphism and association analysis was carried out by mixed model analysis with parameters of innate immunity, in vitro haemolytic complement activity in the classical and alternative pathways, in vivo complement activation expressed as C3c serum concentration, and blood leucocyte proliferation measured in F2 animals of a pig resource population based on cross of Duroc and Berlin miniature pig (DUMI resource population). A single nucleotide polymorphism (SNP) in the promoter region (C > A) of IL12A was identified. Two SNPs were detected in intron 4 of IL12B at positions 192 (A > G) and 437 (C > T). Significant effects of IL12 genotypes on complement activity traits and mitogen-induced leucocyte proliferation were found. The IL12A and IL12B genes were assigned to chromosome13 and 16, respectively, by using radiation hybrid analysis and genetic mapping in the DUMI resource population. Mapping and association analyses promote the IL12 genes as functional and positional candidate gene for disease resistance in pigs.

Relationship between myosin heavy chain isoform expression and muscling in several diverse pig breeds1

The objective of this study was to examine the relationship of the relative abundance of transcripts of myosin heavy chain (MyHC) isoforms and muscling in several diverse pig breeds. The animals used were from 3 pure breeds (Pietrain, Duroc, and Mongcai) and 2 crosses [Duroc x Pietrain (DUPI) and Duroc x Berlin Miniature pigs (DUMI)]. Real-time PCR quantification of MyHC isoforms I, IIa, IIx, and IIb showed that the relative expression of MyHC IIb was greater in pigs with large LM areas in both DUPI (69.6 vs. 53.0%) and DUMI (60.5 vs. 47.5%). In DUPI, similar transcript levels of MyHC I were found in both large and small LM (14.7 and 15.2%), whereas in DUMI animals, these values were 18.4 and 33.5% (P < 0.05). The groups of animals with large and small LM area in the DUPI also tended to differ in MyHC IIa and IIx transcripts. The comparison among different breeds confirmed the trend of high MyHC IIb transcript abundance together with high muscularity. In Pietrain, Duroc, DUPI, and DUMI, MyHC IIb accounted for more than half of the MyHC transcripts (65.4, 59.7, 54.0, and 54.0%). Mongcai showed low MyHC IIb (11.4%) but high type I, IIa, and IIx relative RNA levels (24.1, 28.5, and 35.9%). Frequencies of fibers, determined by muscle fiber staining with ATPase, and relative abundance of MyHC isoforms, determined by quantitative reverse transcription-PCR, of corresponding pairs of type I, IIa, and IIx/ IIb were correlated (r = 0.71, 0.67, and 0.52, respectively). The study demonstrates that MyHC IIb fibers are the most prominent in pigs having large LM area and implies that MyHC IIb is the determining fiber contributing to the differentiation of large and small loin eye muscle area in the pig.

Structural and functional genomics to elucidate the genetic background of microstructural and biophysical muscle properties in the pig

Linkage analyses enable identifying genomic regions that exhibit quantitative trait loci (QTL) without prior hypothesis on the physiology of a trait. Function-oriented expression analyses are a complementary approach to derive hypothesis on the genetic background of phenotypic variation. Muscle fibre types and size affect body composition and meat quality traits. The number and proportion of muscle fibres are to a large extent determined during the prenatal development. Consequently, QTL for muscle fibre, meat quality and carcass traits were detected in a porcine experimental population based on Duroc and Berlin Miniature Pig. Regions with either significant QTL for muscle fibre traits or significant QTL for meat quality and muscularity or both were detected on SSC1, 2, 3, 4, 5, 13, 14, 15 and 16. Here, effects on the complex traits of muscularity and meat quality might be the result of genetic variation primarily affecting fibre type distribution traits. To complement the QTL study expression profiling of prenatal muscle tissue of Duroc and Pietrain was conducted that revealed a list of functional candidate genes for meat quality and carcass traits of various physiological networks. Assignments of these genes to QTL regions highlight them as positional functional candidates. Exemplarily, five genes were analysed further and shown to be associated with meat quality and carcass traits. Further, the relative MYH isotype transcript abundance was found to be associated with muscularity. Relative MYH isotype transcript abundance is proposed as a new phenotype to unravel the genetic background of variation in traits related to muscle and meat properties.

Identification and characterization of an AFLP marker associated with carcass composition in the pig (Brief report)

Abstract. Amplified Fragment Length Polymorphism (AFLP) is a DNA fingerprinting technique that allows genotyping of DNA polymorphisms, mainly single nucleotide substitutions (SNP), across the whole genome with high multiplex ratio and without the need of their prior knowledge. We have successfully combined AFLP with selective genotyping for mapping of quantitative trait loci (QTL) in a F2 resource population based on Duroc and Berlin Miniature pig (DUMI) (WIMMERS et al., 2002). Here we report application of this approach for the identification of loci associated with carcass composition in a herd of commercial German Landrace pigs.

QTL for microstructural and biophysical muscle properties and body composition in pigs.

BackgroundThe proportion of muscle fibre types and their size affect muscularity as well as functional properties of the musculature and meat quality. We aimed to identify QTL for microstructural muscle properties including muscle fibre size, their numbers and fibre type proportions as well as biophysical parameters of meat quality and traits related to body composition, i.e. pH, conductivity, area of M. longissimus dorsi and lean meat content. A QTL scan was conducted in a porcine experimental population that is based on Duroc and Berlin Miniature Pig.ResultsLeast square regression interval mapping revealed five significant and 42 suggestive QTL for traits related to muscle fibre composition under the line-cross model as well as eight significant and 40 suggestive QTL under the half-sib model. For traits related to body composition and biophysical parameters of meat quality five and twelve significant plus nine and 22 suggestive QTL were found under the line-cross and half-sib model, respectively. Regions with either significant QTL for muscle fibre traits or significant QTL for meat quality and muscularity or both were detected on SSC1, 2, 3, 4, 5, 13, 14, 15, and 16. QTL for microstructural properties explained a larger proportion of variance than did QTL for meat quality and body composition.ConclusionMicrostructural properties of pig muscle and meat quality are governed by genetic variation at many loci distributed throughout the genome. QTL analysis under both, the line-cross and half-sib model, allows detecting QTL in case of fixation or segregation of the QTL alleles among the founder populations and thus provide comprehensive insight into the genetic variation of the traits under investigation. Genomic regions affecting complex traits of muscularity and meat quality as well as microstructural properties might point to QTL that in first instance affect muscle fibre traits and by this in second instance meat quality. Disentangling complex traits in their constituent phenotypes might facilitate the identification of QTL and the elucidation of the pleiotropic nature of QTL effects.

Polymorphisms of the androgen receptor gene associate with fatness, uterus and ovary measurements in the pig

Abstract. Quantitative trait loci, QTL, for fatness and carcass traits in pigs have been recently mapped to the X chromosome approximately at the position where the androgen receptor gene (AR) is localized. The AR acts as a nuclear transcription factor regulating expression of a number of androgenic response genes during various stages of sexual development. The present study aimed to analyze association of the AR genotype on traits related to fatness and phenotype of primary female sexual organs, ovary and uterus. Animals of a F2 resource population based on Duroc and Berlin Miniature pig were genotyped at a multi-allelic microsatellite marker (CCTTT)n situated in the 5' untranslated region and a bi-allelic CAG-insertion/deletion polymorphism (CAG-INDEL) within exon 1 of the AR. Association analysis showed that the AR genotype both at the CAG-INDEL and microsatellite affect almost all fatness traits measured. The D allele inherited from Duroc was associated with the decrease of fat thickness. The AR genotypes also affect uterus and ovary measurements. The pigs homozygous for D allele were likely to have a lighter uterus, shorter uterus horns, oviducts and smaller ovaries than pigs homozygous for the M allele. Our results confirm the previously reported QTL for fatness traits and provide evidence for a QTL affecting dimensions of uterus and ovary on the X chromosome. The AR is a positional functional candidate gene for both trait complexes.

SNP detection and genetic mapping of porcine genes encoding enzymes in hepatic metabolic pathways and evaluation of linkage with carcass traits

We have previously identified and mapped porcine expressed sequence tags (ESTs) derived from genes that are preferentially expressed in liver. The aim of the present study was to identify single nucleotide polymorphisms (SNPs) in porcine genes encoding enzymes in hepatic metabolic pathways and use the SNPs for mapping. Furthermore, these genes, which are involved in utilization and partitioning of nutrients, were examined for their effects on carcass and meat quality traits by linkage analyses. In total, 100 ESTs were screened for SNPs by single strand conformation polymorphism analyses across a diverse panel of animals with a 36% success rate. Twelve of 36 polymorphic loci segregated in a three-generation Duroc x Berlin Miniature Pig (F2) resource population, the DUMI resource population, and were genetically mapped. Interval mapping of the corresponding chromosomes was performed to verify mapping of the genes within quantitative trait loci (QTL) regions detected in this resource population. QTL with genome-wide significance were detected in the vicinity of GNMT, ESTL147 and HGD. These loci therefore are positional candidate genes.

Polymorphisms of the porcine androgen receptor gene affecting its amino acid sequence and expression level

Diverse physiological effects of the androgen receptor (AR), a nuclear transcription factor, and its mapping position within a quantitative trait loci (QTL) region on chromosome X propose it as an interesting candidate gene for pig reproduction and performance. Therefore, the aims of this study were isolation of the gene and detection of polymorphisms as a tool for association study and analysis of functional properties of the porcine AR. The mRNA and promoter sequences were obtained and screened for polymorphisms. Based on comparative sequencing, eight single nucleotide polymorphisms (SNPs), TG- and T-insertion/deletetion polymorphisms (INDELs) upstream transcription initiation sites, three SNPs in the 5′-untranslated region (UTR), one microsatellite (CCTTT)n in the intron of 5′-UTR, and a CAG-INDEL in exon 1 were detected. Two haplotypes originated from Duroc and Berlin Miniature Pig were segregating in the DUMI-F2 resource population. Characterization of the porcine AR promoter showed two conserved transcription start sites, a consensus sequence of GC-box and a homopurine/homopyrimidine stretch at similar locations compared to the human, rat and mouse as well as sequences similar to androgen response elements (ARE). The AR mRNA expression levels determined by real-time RT-PCR in various tissues of female pigs were high in ovary (100%) and adrenal gland (83.9% relative to ovary), moderate in uterus (61.6%) and liver (47.4%), and low in pituitary gland (1.3%) as well as in tonsil, muscle, mammary gland, leukocyte and jejunum (less than 1%). Detection of the AR mRNA transcripts in liver revealed that hemizygous males carrying the AR haplotype descended from Berlin Miniature pig had higher relative AR expressions than did those with the Duroc haplotype. Here we showed that the porcine AR is a highly polymorphic gene. Polymorphisms identified in the present study affect the predicted amino acid sequence as well as consensus transcription factor binding sites and are associated with the allele-specific differences of the AR mRNA transcript level in liver, reinforcing AR as a potential candidate gene for traits related to pig reproduction and performance.

Polymorphisms of the porcine androgen receptor gene affecting its amino acid sequence and expression level

Diverse physiological effects of the androgen receptor (AR), a nuclear transcription factor, and its mapping position within a quantitative trait loci (QTL) region on chromosome X propose it as an interesting candidate gene for pig reproduction and performance. Therefore, the aims of this study were isolation of the gene and detection of polymorphisms as a tool for association study and analysis of functional properties of the porcine AR. The mRNA and promoter sequences were obtained and screened for polymorphisms. Based on comparative sequencing, eight single nucleotide polymorphisms (SNPs), TG- and T-insertion/deletetion polymorphisms (INDELs) upstream transcription initiation sites, three SNPs in the 5′-untranslated region (UTR), one microsatellite (CCTTT)n in the intron of 5′-UTR, and a CAG-INDEL in exon 1 were detected. Two haplotypes originated from Duroc and Berlin Miniature Pig were segregating in the DUMI-F2 resource population. Characterization of the porcine AR promoter showed two conserved transcription start sites, a consensus sequence of GC-box and a homopurine/homopyrimidine stretch at similar locations compared to the human, rat and mouse as well as sequences similar to androgen response elements (ARE). The AR mRNA expression levels determined by real-time RT-PCR in various tissues of female pigs were high in ovary (100%) and adrenal gland (83.9% relative to ovary), moderate in uterus (61.6%) and liver (47.4%), and low in pituitary gland (1.3%) as well as in tonsil, muscle, mammary gland, leukocyte and jejunum (less than 1%). Detection of the AR mRNA transcripts in liver revealed that hemizygous males carrying the AR haplotype descended from Berlin Miniature pig had higher relative AR expressions than did those with the Duroc haplotype. Here we showed that the porcine AR is a highly polymorphic gene. Polymorphisms identified in the present study affect the predicted amino acid sequence as well as consensus transcription factor binding sites and are associated with the allele-specific differences of the AR mRNA transcript level in liver, reinforcing AR as a potential candidate gene for traits related to pig reproduction and performance.

Molecular cloning and sequencing of porcine C5 gene and its association with immunological traits.

The complement system helps in the lysis of invading pathogens and modulates the inflammatory as well as the humoral and cellular immune responses. C5 mediates many potent inflammatory and cytolytic events after proteolytic activation by complement convertase enzymes. Hence, to investigate the role of pig C5 ( pC5) as a candidate gene for disease resistance in pigs, the complete cDNA of pC5 was sequenced, screened for single nucleotide polymorphisms (SNPs), and an association analysis with various immunological parameters measured in F2 animals of a pig resource population based on a cross of Duroc and Berlin miniature pigs (DUMI) was carried out. In total, 5,422 bp of pC5 cDNA was sequenced, which codes for the 1,677-amino-acid precursor of C5. Four polymorphic sites were detected, one of which was segregating in the DUMI population in three genotypic patterns: AA, AC and CC. Classical (CH50) and alternative (AH50) complement activities, C3c levels, haptoglobin (HP) acute phase protein levels, and antibody titers against Mycoplasma (Mk) and Aujesky (ADV) vaccines were measured in the resource population. Association analysis between C5 and the immunological parameters was carried out using repeated measures mixed and general linear model analysis. The homozygote AA was found to be significantly different from the other two genotypes with respect to AH50 and CH50, whereas genotype CC was found to be significantly different from the other genotypes for C3c and HP levels. No significant difference could be seen between genotypes for antibody titers against vaccinations. Association of C5 with complement activity traits and acute phase proteins promotes pC5 as a candidate gene for innate disease resistance.

Association of the porcine C3 gene with haemolytic complement activity in the pig

The complement component C3 plays an essential role in the activated complement system, which is involved in phagocytosis, inflammation and immunoregulation to destroy infectious microorganisms. The C3 molecule has more implications in the general defence mechanisms. In this study, the porcine C3 cDNA sequences including 5'- and 3'- flanking regions were determined and the polymorphisms in this gene were identified to carry out an association analysis between C3 and complement activity traits. Porcine C3 gene has high homology with human C3. Five single nucleotide polymorphisms (SNPs) and one microsatellite were detected in the porcine C3 gene. Haemolytic complement activity of alternative and classical pathways (ACH, CCP) was measured in 416 F2 animals of a crossbred of Duroc × Berlin Miniature Pig, which were immunized with Mycoplasma, Aujeszky and PRRS vaccines. C3 markers were found to be significantly associated (P < 0.05) with both ACP and CCP. Animals with the more frequent haplotype present in Duroc and other commercial breeds exhibit higher ACP and CCP levels than the animals with haplotype specific to some Berlin Miniature Pigs. The association of C3 with complement activity reinforces the importance of C3 as a candidate gene for natural resistance to microorganisms.

Association of the porcine C3 gene with haemolytic complement activity in the pig.

The complement component C3 plays an essential role in the activated complement system, which is involved in phagocytosis, inflammation and immunoregulation to destroy infectious microorganisms. The C3 molecule has more implications in the general defence mechanisms. In this study, the porcine C3 cDNA sequences including 5'- and 3'- flanking regions were determined and the polymorphisms in this gene were identified to carry out an association analysis between C3 and complement activity traits. Porcine C3 gene has high homology with human C3. Five single nucleotide polymorphisms (SNPs) and one microsatellite were detected in the porcine C3 gene. Haemolytic complement activity of alternative and classical pathways (ACH, CCP) was measured in 416 F2 animals of a crossbred of Duroc × Berlin Miniature Pig, which were immunized with Mycoplasma, Aujeszky and PRRS vaccines. C3 markers were found to be significantly associated (P < 0.05) with both ACP and CCP. Animals with the more frequent haplotype present in Duroc and other commercial breeds exhibit higher ACP and CCP levels than the animals with haplotype specific to some Berlin Miniature Pigs. The association of C3 with complement activity reinforces the importance of C3 as a candidate gene for natural resistance to microorganisms.

Molecular characterization of the pig C3 gene and its association with complement activity.

The complement system catalyzes direct lysis of micro-organisms and modulates phagocytosis, inflammation, humoral and cellular immune responses. Since the complement protein C3 is the central component within all pathways of complement activation, C3 is a candidate gene for complement activity and also for improved protection against many pathogens. The pig C3 gene was sequenced, screened for polymorphisms, and analyzed for association with hemolytic complement activity of the alternative and classical pathway (AH(50), CH(50)). C3c serum levels and haptoglobin (HP) serum concentrations were measured before and after vaccination against Mycoplasma hyopneumoniae, Aujeszky virus, and porcine reproductive and respiratory syndrome virus in F2 animals of a pig resource population based on crossbreeding of Duroc and Berlin Miniature Pig. The genomic C3 sequence covers 444 bp of promoter region, 41 exons and 40 introns, as well as 881 bp of the 3'-flanking region. The cDNA codes for a 1,661-amino acid precursor C3. Five polymorphic sites were detected in the 5'-UTR, intron 13, exon 15, exon 30, and the 3'-UTR. Within the resource population two haplotypes were found to segregate. Analysis of variance applying a repeated measures model revealed a significant effect of the interaction of C3 genotype and time of measurement relative to immunization on CH(50), AH(50,)and C3c that is likely to be due to variation of C3 expression. In contrast, the time course of the HP acute-phase reaction is not associated with C3 genomic variation. The association of C3 with complement activity indicates the importance of C3 as a candidate gene for natural resistance to micro-organisms, although the causative polymorphism modulating the expression of C3 remains to be delineated.

Phenotypic variations of muscle fibre and intramuscular fat traits in Longissimus muscle of F 2 population Duroc×Berlin Miniature Pig and relationships to meat quality

In Longissimus muscle from a F 2 population of Duroc×Berlin Miniature Pigs, micro-structural fibre traits and fatty acid composition were investigated to calculate correlation coefficients between these traits and meat quality. The animals of the F 2 population exhibited low carcass weight (55.7±11.2 kg), low meat percentage (35.0±8.4%) but a relatively high intramuscular fat content (3.52±1.44%) compared to pure bred animals (F 0). No unacceptable meat quality was observed. The variation coefficients of carcass composition, muscle fibre traits, and fat traits were high enough to allow the analysis of candidate genes which influence the growth of muscle fibres, fat cells, and meat quality. Phenotypic correlation coefficients between muscle fibre characteristics and meat quality traits were low whereas fatty acid composition and meat quality were more closely related. The correlation coefficients between muscle fibre traits and fatty acid composition ranged from 0.10 to 0.40. The relationship between a low quotient of n-6/ n-3 fatty acids in muscle and greater fibre sizes, higher percentages of the oxidative fibre type and higher capillary density was noteworthy indicating good conditions for muscle growth and meat quality.