Genetic diversity in wild (Sus scrofa scrofa) and domestic (Sus scrofa domestica) pigs and their hybrids based on polymorphism of a fragment of the D-loop region in the mitochondrial DNA

We examined the variation in mitochondrial DNA by sequencing the D-loop region in wild and domestic (large-white breed) pigs, in hybrids between domestic and wild pigs, and in Monteiro pigs. A D-loop fragment of approximately 330 bp was amplified by PCR. Sequencing of DNA amplicons identified haplotypes previously described as European and Asian types. Monteiro pigs and wild pigs had European haplotypes and domestic pigs had both European and Asian haplotypes.     

The contribution of social effects to heritable variation in finishing traits of domestic pigs (Sus scrofa)

Social interactions among individuals are ubiquitous both in animals and in plants, and in natural as well as domestic populations. These interactions affect both the direction and the magnitude of responses to selection and are a key factor in evolutionary success of species and in the design of breeding schemes in agriculture. At present, however, very little is known of the contribution of social effects to heritable variance in trait values. Here we present estimates of the direct and social genetic variance in growth rate, feed intake, back fat thickness, and muscle depth in a population of 14,032 domestic pigs with known pedigree. Results show that social effects contribute the vast majority of heritable variance in growth rate and feed intake in this population. Total heritable variance expressed relative to phenotypic variance was 71% for growth rate and 70% for feed intake. These values clearly exceed the usual range of heritability for those traits. Back fat thickness and muscle depth showed no heritable variance due to social effects. Our results suggest that genetic improvement in agriculture can be substantially advanced by redirecting breeding schemes, so as to capture heritable variance due to social effects.     

Sarcocystis miescheriana infection in domestic pigs (Sus scrofa) in the Philippines

Sarcocystis miescheriana sarcocysts were identified in skeletal muscles of 9 (27%) of 33 swine slaughtered for human consumption. Sarcocysts were 144-180 microm x 20-38 microm in size. Ultrastructurally, the cyst wall resembled the type 10 sarcocyst wall. The villar protrusions (VP) were 3-4.5 microm long and 0.6-1.2 microm wide and had prominent longitudinally arranged microtubules extending from the VP tips to the granular layer (=ground substance). The parasitophorous vacuolar membrane with its underlying electron-dense layer (EDL) measured 25 nm in thickness. The base of the VP exhibited minute (0.42-0.87 microm) bulblike inpocketings. Each VP had 80-90 microtubules situated underneath the EDL. The granular layer was 0.5-1.2 microm thick, and contained hairlike microtubules continuous with those of the VP core. This is the first report of S. miescheriana in Philippine domestic pigs Sus scrofa.     

Detection of hybrids between wild boars (Sus scrofa scrofa) and domestic pigs (Sus scrofa f. domestica) in Greece,using the PCR-RFLP method on melanocortin-1 receptor (MC1R) mutations

The melanocortin-1 receptor (MC1R) regulates melanogenesis in mammals within the mammalian melanocyte and the hair follicle. Common variations (polymorphisms) in the MC1R gene are associated with normal differences in skin and hair colour. So far, a unique MC1R allele (E+) has been identified in European wild boar (Sus scrofa scrofa), associated with the wild-type coat colour (variable shades of brown) that is not found in any of the domestic breeds. In addition, a series of alleles found in pigs, some of which observed only in particular breeds, have been proposed as markers in breed traceability systems. The current study is an attempt to detect possible hybrids between wild boars and domestic pig breeds as well as to identify races of pig that are not purebred. For this purpose, wild boars were analysed against Large White pigs, applying the PCR-restriction fragment length polymorphism (RFLP) method. A high percentage (16.7%) of hybrids was detected within a breeding station compared with the percentage of hybrids within the populations of free-ranging wild boar (5.0%). These results should be taken into consideration for future restocking operations to avoid the chance of outbreeding depression, which is more intense when local populations are introgressed by gene pools from domesticated, usually inbred, animals.     

The high resolution R-banded karyotype of the domestic pig, Sus scrofa domestica L

A representative haploid R-banded karyotype of the domestic pig, and a diagrammatic representation of the banding patterns at the 550 band level are presented.     

Introduction of two chromosomal translocations of Sus scrofa nigripes and Sus scrofa scrofa into the genome of Sus scrofa domestica

Summary Hybrids between wild and domestic pigs with two types of translocations in the karyotype were studied. The translocations of type I were first detected in a population of the Middle Asian wild boars. Type II was identified in a populations of the Central European subspecies. A large number of Middle Asian and Central European hybrids and their F₁-F₃ hybrids from crosses with domestic pigs were viable. By means of differential chromosome staining, the mechanism of the formation of synthetic karyotypes, as well as some features of translocation inheritance, were established.The introduction of two translocations into a single genome and the same chromosome set of these hybrids not only modified chromosome number, but also the composition of the linkage groups. The hybrids heterozygous for two translocations and their hybrid progeny are characterized by an obligatory heterozygozity for a large number of genes, gene complexes and linked genes. It is suggested that this heterozygozity may be associated with heterotic events. The use of such hybrids in pig breeding may provide heterosis for viability and productivity.     

A chromosome 1-specific DNA library from the domestic pig (Sus scrofa domestica).

Chromosomes were prepared from lymphocytes of a male domestic pig and flow-sorted on a dual-laser FACS. Twenty spots were observed, corresponding to the known pig karyotype of 18 pairs of autosomes plus the X and Y. DNA was isolated from 10,000 copies of the presumed chromosome 1 spot, restricted with Sau3A, ligated into the vector pGEM4z, and PCR amplified using universal primers; the products were then re-ligated into pUC18. After transformation into Escherichia coli, 210,000 independent colonies were obtained, 5% of which contained only vector DNA. The average insert size of the library was 405 bp. Southern blotting revealed that 36% of the clones contained single-copy DNA and that the remainder contained moderately or highly repetitive DNA. Screening with a (CA)n probe revealed that roughly 1% of the clones contained microsatellite sequences. A bulk insert of the library was biotinylated by PCR and used as a probe for chromosomal in situ suppression hybridization to pig chromosomes, which confirmed that the library is specific for chromosome 1. However, sequences from the centromeric and telomeric regions seem to be underrepresented in the library.     

Long-term evaluation of a selective retrograde coronary venous perfusion model in pigs (Sus scrofa domestica)

The lack of suitable target vessels remains a challenge for aortocoronary bypass grafting in end-stage coronary heart disease. This study aimed to investigate the arterialization of cardiac veins as an alternative myocardial revascularization strategy in an experimental long-term model in pigs. Selective retrograde perfusion of a coronary vein (aorta to coronary vein bypass, retrobypass) before ligation of the ramus interventricularis paraconalis (equivalent to the left anterior descending artery in humans) was performed in 20 German Landrace pigs (Sus scrofa domestica). Retroperfusion of the left anterior descending vein was performed in 10 pigs (RP+) but not in the other 10 (RP-), and the vena cordis magna was ligated (L+) in 5 pigs in each of these groups but left open (L-) in the remaining animals. Hemodynamic performance (for example, cardiac output) was significantly better in the group that underwent selective retroperfusion with proximal ligation of vena cordis magna (RP+L+; 4.1 L/min) compared with the other groups (RP+L-, 2.5 L/min; RP-L+, 2.2 L/min; RP-L-, 1.9 L/min). Long-term survival was significantly better in RP+L+ pigs (112±16 d) than in all other groups. Histologic follow-up studies showed significantly less necrosis in the RP+L+ group compared with all other groups. Venous retroperfusion is an effective technique to achieve long-term survival after acute occlusion of the left anterior descending artery in a pig model. In this model, proximal ligation of vena cordis magna is essential.     

Pre- and perinatal oxygen transport in mammals: the embryonic hemoglobins of the domestic pig (Sus scrofa domestica)

Pigs express two globin genes of beta-type, the epsilon- and chains during their embryonic stage. With the alpha- and epsilon-chains they form four embryonic hemoglobins. We describe here in detail the experimental procedures for sequencing the epsilon- and chains from the pig (Sus scrofa domestica) and we discuss the data with respect to their special functional properties. From the components Gower I and Heide I, we obtained all embryonic chains by chromatography on CM-Cellulose. The sequence of the tryptic peptides of the beta-type chains was established by automatic Edman-Begg degradation. They were aligned by comparison with the corresponding human chains. The epsilon-chains from man and pig differ in 20 positions, porcine and epsilon-chains only in 4 positions. Up to now these have only been found in pigs. A fetal hemoglobin (gamma-chains) was not observed. As a result of this work the sequences of all peptide chains of pig's hemoglobin are determined.     

Characterization of hepatic drug-metabolizing activities of Bama miniature pigs (Sus scrofa domestica): comparison with human enzyme analogs

We used various substrates and selective inhibitors of human cytochrome P450 (CYP) isozymes as probes to study the metabolism of liver microsomes from Chinese Bama miniature pigs. Nifedipine oxidation (NOD) and testosterone 6beta-hydroxylation (6beta-OHT) activities were similar between human liver microsomes and those from Bama miniature pigs. However, compared with those from humans, liver microsomes from Bama miniature pigs showed decreased phenacetin O-deethylation, coumarin 7-hydroxylation, and chlorzoxazone 6-hydroxylation activities, whereas dextromethorphan O-demethylation activity was increased. Ketoconazole selectively inhibited NOD and 6beta-OHT activities in microsomes from Bama pigs, and 8-methoxypsoralen and tranylcypromine inhibited coumarin 7-hydroxylation in pig microsomes. However, furafylline and quinidine failed to selectively inhibit phenacetin O-deethylation and dextromethorphan O-demethylation in microsomes from Bama pigs, whereas chlormethiazole more efficiently inhibited coumarin 7-hydroxylation activity than chlorzoxazone 6-hydroxylation in pig microsomes. Our results suggest that liver microsomes from Chinese Bama miniature pigs are similar to those from humans in regard to metabolism of nifedipine and testosterone (both are probe substrates for human CYP3A4). In addition, chemical inhibitors used as specific probes for human P450 enzymes did not always show the same selectivity toward corresponding enzyme activities in liver microsomes from Bama pigs. However, ketoconazole (a potent inhibitor of human CYP3A4) could be used as a selective inhibitor probe for the NOD and 6beta-OHT activities in liver microsomes from Chinese Bama miniature pigs.     

Characterization of a polymorphic IGLV gene in pigs (Sus scrofa)

Swine, unlike other artiodactyls, but similar to humans, utilize both lambda and kappa light chain isotypes almost equally in the generation of their antibody repertoire. The porcine antibody light chain loci have previously been characterized in a single Duroc sow in which was seen extensive allelic variation between light chain genes on homologous chromosomes. However, the extent of variation between individuals is completely unknown. Using deep sequencing of cDNA-derived amplicons from five pigs, we report the identification and characterization of an IGLV gene that is functional and highly expressed in some animals, yet completely absent in others. Our findings provide a possible rationale for the known individual-to-individual variation in antibody responses to vaccination, infectious challenge, and subsequent disease outcome.