Linkage between the porcine genes encoding immunoglobulin heavy-chain allotypes and some serum alpha-protease inhibitors: a conserved linkage in pig, mouse and human

Polymorphic plasma postalbumins of some domestic animals (pig PO2, horse Xk and dog Pa proteins) identified as homologous to human plasma alpha 1B-glycoprotein

Pig, horse and dog plasma proteins, separated by horizontal polyacrylamide gel electrophoresis (pH 9.0) and electrophoretically transferred to nitrocellulose membranes, were tested for cross-reaction with antiserum to human plasma alpha 1B-glycoprotein (alpha 1B). The results showed that one previously reported polymorphic plasma postalbumin in each of these species (pig PO2, horse Xk and dog Pa protein) was homologous to human plasma alpha 1B. In the light of the previously known genetic linkages in these species, this implied: (1) alpha 1B gene is close linked to Phi, Pgd and Hal (halothane sensitivity locus) loci in pigs; and (2) alpha 1B gene is linked to ME1 and Phi loci in horses. This suggested that the alpha 1B gene may also be found to be closely linked to gene(s) controlling susceptibility to malignant hyperthermia in humans and other mammals.

Cosegregation of two allotypes G9 and G16 with the alpha-protease inhibitor variants in pigs

The association between genes encoding for two serum protein antigens (G9 and G16) and alpha-protease inhibitors was analysed in pigs. A recombination frequency between PI and locus controlling G9 and G16 allotypes varied from 0 to 4.8 cM. Data from appropriate matings are consistent with a gene order of PI1-PO1A-PO1B-PI2-(G9, G16).

Recombination rates and gene order for some serum alpha-protease inhibitors and immunoglobulin heavy-chain allotypes in pigs

Linkage analysis between the genes coding for immunoglobulin heavy-chain allotypes and variants of some serum alpha-protease inhibitors produced lod scores above the significance limit of 3. The maximum likelihood estimate of the recombination fraction (theta) ranged from 0.15 to 0.20. Since this is the second report on this linkage group in pigs, the linkage is confirmed. Data from appropriate matings are consistent with a gene order of Pi1-Po1A-(Po1B)-Pi2-Igh1.

Porcine alpha-1-antitrypsin (PI): cDNA sequence, polymorphism and assignment to chromosome 7q2.4- > q2.6

A cDNA clone encoding the complete coding sequence for porcine alpha-1-antitrypsin (or alpha 1-protease inhibitor, PI) was isolated and its DNA sequence determined. The cDNA is assumed to encode alpha-1-antitrypsin on the basis of its sequence similarity to the corresponding cDNAs for human, baboon, rat, mouse, sheep and cow. The porcine cDNA clone was used in conjunction with BamHI, KpnI, MspI, SacI, TaqI and XbaI to develop restriction fragment length polymorphism-based genetic markers for linkage mapping in pigs. The cDNA has also been used to map the porcine PI locus to chromosome 7q2.4- > q2.6 by radioactive in situ hybridization. Thus, the PI locus has been added to the developing physical and genetic maps of the porcine genome.

Localization of the IGHG, PRKACB, and TNP2 genes in pigs by in situ hybridization

The porcine genes encoding the immunoglobulin gamma heavy chain (IGHG), cAMP-dependent protein kinase catalytic beta subunit (PRKACB), and transition protein 2 (TNP2) were mapped to Chromosomes (Chrs) 7 q25-q26, 6q31-q33, and 3p13-cent, respectively, by in situ hybridization. Localization of the IGHG gene confirms the assignment of linkage group III to Chr 7. Our results show that the IGHG locus in pigs, similar to the situation in other mammalian species, viz. humans, mouse, cattle, and river buffaloes, is located on the terminal region of the chromosome. The assignment of the PRKACB gene extends the homology observed between porcine Chr 6q and human Chr 1p. Mapping of the TNP2 gene provides the first marker assigned to the p arm of Chr 3 in pigs. The present study contributes to the development of the physical gene map in pigs and also bears significance in terms of comparative gene mapping.

Preferential mammary storage and secretion of immunoglobulin gamma (IgG) subclasses in swine

Levels of three immunoglobulin gamma (IgG) subclasses, IgGA, IgGB and IgGC, were measured in sow sera, mammary glands, colostrum and milk samples by the single radial immunodiffusion. Serum IgGA and IgGB levels, but not IgGC, showed time dependent variations during gestation and lactation periods. The IgGA level started to decline at day 106 of gestation, reached its minimum at farrowing, and returned to the pre-gestation level 1-3 weeks after weaning. The serum IgGB level started to decrease at day 111 of gestation, reached its minimum at farrowing, and returned to the initial gestation level 1 week after farrowing. A notable decrease (P less than 0.1) in serum IgGC level was observed only on the day of farrowing. IgGA and IgGB were preferentially stored in mammary glands of full-term pregnant sows and secreted into colostrum after farrowing. In contrast, relatively small amounts of IgGC were stored in the mammary glands and secreted into colostrum. These data are interpreted as an indication that the preferential storage of IgGA and IgGB in the mammary gland of sows occurs at the time of significant decreases of these two IgG subclasses in the sera during late gestation and early lactation.

Linkage of plasminogen (PLG) and apolipoprotein(a) (LPA) in baboons

Four allelic forms of serum plasminogen (PLG) were detected in baboons (Papio hamadryas Linneaus 1758) by isoelectric focusing and were determined to be inherited as autosomal codominant traits. Linkage analysis of data from 179 progeny and their parents revealed that PLG is tightly linked (lod score = 30.20) to the gene encoding apolipoprotein(a) (LPA), as in humans. No recombinant individuals were identified. This is the first linkage detected between PLG and LPA in any species other than humans and is the first genetic linkage identified in a nonhuman primate species by family studies.

Polymorphism of pig serum alpha-protease inhibitor-3 (PI3) and assignment of the locus to the Pi1, Po1A, Po1B, Pi2, Igh linkage group

Polymorphism of an alpha-protease inhibitor, PI3, in pig serum samples was detected using 2D agarose gel (pH 5.4)--polyacrylamide gel (pH 9.0) electrophoresis. Evidence was obtained that the five variants observed (A, B1, B2, C and D) are under genetic control by codominant alleles (Pi3A, Pi3B1, Pi3B2, Pi3C and Pi3D) at one autosomal locus. Variants A, B1, B2 and C inhibited chymotrypsin; there was no appreciable inhibition of trypsin and papain. Variant D did not inhibit chymotrypsin, and therefore its classification as a PI3 variant was put in question. PI3 typing was not possible in about 50% of the studied pigs since in those cases the PI3 variants were either too weak or absent. On the basis of backcross matings and haplotyping in complete families for protease inhibitor loci Pi1, Po1A, Pi2 and Pi3 it was proved that the Pi3 locus belongs to the protease inhibitor gene cluster, and the position of the locus in the linkage group was proposed as being Pi1-Po1A-(Po1B)-Pi3-Pi2-(Igh1, Igh2, Igh3, Igh4).

Genetic polymorphism of human plasma alpha 1B-glycoprotein: phenotyping by immunoblotting or by a simple method of 2-D electrophoresis

Genetic polymorphism of human plasma (serum) alpha 1B-glycoprotein (alpha 1B) was observed using one-dimensional horizontal polyacrylamide gel electrophoresis (PAGE) pH 9.0 of plasma samples followed by Western blotting with specific antiserum to alpha 1B. A simple method of two-dimensional agarose gel electrophoresis (pH 5.4)-horizontal PAGE (pH 9.0) of plasma samples, followed by general protein staining, was reported as an alternative method for alpha 1B typing. The three different phenotypes of alpha 1B observed (designated 1-1, 1-2, and 2-2) were apparently identical to those reported by Altland et al. (1983), who used double one-dimensional electrophoresis. Family data supported the hypothesis that the three alpha 1B phenotypes are determined by two codominant alleles at an autosomal locus, designated A1B. Allele frequencies in a Swedish population were: A1B1, 0.937; A1B2, 0.063; PIC, 0.111. For clues on linkage relationships of human A1B, the previously known linkages of A1B in pigs and horses, including the one between A1B and the gene that determines susceptibility to malignant hyperthermia in pigs were discussed.