Genetic polymorphism and close linkage of two plasma protein loci in dogs

By using a simple method of two-dimensional horizontal electrophoresis, phenotypes of an unidentified plasma protein (PA4) were determined in 967 dogs belonging to 43 different breeds. Two codominant, autosomal alleles (F and S) of PA4 were reported. While many of the breeds of middle and north-eastern Asia (akita inu, Alaskan malamute, chow chow, samoyed, Siberian husky and Tibetan terrier) showed a substantial frequency (0.1 to 0.6) of the S allele, a majority of the European breeds had only the F allele. Evidence was provided that the PA4 locus is closely linked to the plasma pretransferrin 1 locus (PRT1). No recombinant was observed in 45 informative offspring studied. In nearly all breeds, the PA4 S allele was almost always in coupling phase with the PRT1 F allele.

Two-dimensional gel electrophoresis of sheep plasma proteins: genetic polymorphism of an alphal-protease inhibitor and a post-transferrin

Two-dimensional electrophoretic analysis of sheep plasma proteins was performed by a first-dimension separation in agarose gel (pH 5.0) followed by a second-dimension one in horizontal polyacrylamide gel (pH 9.0). This method resulted in improved and reproducible separation of many alpha- and beta-globulins. Two groups of alpha 1-globulins, designated Pi-1 and Pi-2, were found to be protease inhibitors. These two inhibitors differed from each other in protease inhibitory spectra. Genetic polymorphism was observed for the Pi-2 protein and another unidentified protein, tentatively designated as post-transferrin (Ptf). Family data supported the hypothesis that Pi-2 and Ptf types were controlled by codominant, autosomal alleles. Three Pi-2 alleles and two Ptf alleles were observed in one population of the Gotland breed of sheep. The analysis of data from 50 informative matings showed no evidence of genetic linkage between the Pi-2, Ptf and transferrin (Tf) loci in the population of sheep studied.

Two-dimensional gel electrophoresis of cattle plasma proteins: genetic polymorphism of an alpha 1-protease inhibitor

Two-dimensional electrophoretic analysis of cattle plasma proteins was done by a first dimension separation in agarose gel (pH 5.0), followed by a second dimension in horizontal polyacrylamide gel (pH 9.0). This method resulted in improved and reproducible separation of many alpha- and beta-globulins. Three groups of alpha-globulins, designated Pi-1, Pi-2 and Pi-3, were found to inhibit the esterolytic activity of bovine trypsin and bovine chymotrypsin. Pi-2 showed appreciable inhibition only for trypsin and genetic polymorphism was observed for this protein. Family data supported the hypothesis that the three Pi-2 types observed were controlled by two codominant, autosomal alleles. The occurrence of a third Pi-2 allele was also postulated in some animals studied. The frequency of the most common allele, Pi-2s, ranged from 0.5-0.8 in the different breeds of cattle studied (Swedish Red and White, Friesian, Jersey, Charolais and Simmental). The post-transferrins Ptf-1 and Ptf-2 in cattle plasma were shown to be two different genetic systems.

A previously reported polymorphic plasma protein of dogs and horses, identified as apolipoprotein A-IV

By using immunoblotting with antiserum specific to human plasma apolipoprotein A-IV (apoA-IV), a previously reported polymorphic plasma protein of dogs viz postalbumin-2 (Pa2) and one of horses viz serum protein 2 (SP2), were identified as apoA-IV of these species. This along with earlier published results implied that: (1) both dog and horse show a high degree of polymorphism at the APOA4 locus with three common alleles in each of the two species; and (2) apoA-IV phenotyping in these two species can be done by analysing plasma/serum samples by a simple method of two-dimensional electrophoresis, conducted under non-denaturing conditions, followed by general-protein staining of gels.

Close linkage between the albumin and Gc loci in the horse

Evidence for close linkage between the structural loci for albumin and Gc protein in the horse was presented. A recombination frequency (c) of 0.009 +/- 0.006 (95% confidence limits: 0.001 less than c less than 0.032) was estimated. These results were based on a study of a large sire family comprising 223 offspring from informative matings. No evidence of linkage disequilibrium was observed in one horse population studied.

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.

Genetic variation at a pig serum protein locus, Po-2 and its assignment to the Phi, Hal, S, H, Pgd linkage group

Two-dimensional agarose gel (pH 5.4)-polyacrylamide gel (pH 9.0) electrophoresis of pig serum samples revealed a new serum protein (postalbumin-2, PO-2) polymorphism. Family data supported the hypothesis that the three PO-2 phenotypes observed were controlled by two codominant, autosomal alleles (Po-2F and Po-2s) at a single locus. The frequency of Po-2F in Swedish Landrace and in Swedish Yorkshire breeds was estimated at 0.74 and 0.65, respectively. Evidence was presented for close genetic linkage between Po-2 and the red cell phosphohexose isomerase locus (Phi). A recombination frequency of 3.2% was obtained from double backcross material. Data obtained in a Danish Landrace material showing linkage between the Po-2 locus and the H blood group locus, the Pgd locus and Hal (locus for halothane sensitivity) are also given. A total of seven recombinants were observed. They show that Po-2 is a new locus in a previously established linkage group. The likely sequence of the loci is: Phi, Hal, S, H, Po-2, Pgd.

Polymorphic plasma postalbumin (Po) of llamas and alpacas identified as Gc protein

Immunoblotting with antiserum specific to human Gc protein was used to identify Gc protein as the previously reported polymorphic plasma postalbumin (Po) of llamas and alpacas. This is the first report of Gc polymorphism in camelid species. One Gc variant appeared to be identical in llamas, alpacas, dromedaries and bactrian camels.

Genetic polymorphism and close linkage of two alpha 1-protease inhibitors in horse serum

Two-dimensional electrophoretic analysis of horse serum proteins was done by a first-dimension separation in agarose gel (pH 5.4) followed by a second-dimension separation in horizontal polyacrylamide gel (pH 9.0). This method resulted in improved and reproducible separation of many alpha-globulins. Two groups of alpha 1-globulins, designated Pi1 and Pi2, were found to be protease inhibitors. Preliminary studies indicated that Pi1 and Pi2 proteins differed from each other in molecular weight and in protease inhibiting spectra. Extensive polymorphism was observed for both these proteins. Family data supported the hypothesis that Pi1 and Pi2 types were controlled by autosomal codominant alleles. For both Pi1 and Pi2 systems, most of the homozygous types showed two fractions each while the heterozygous types had 4 fractions. Six Pi1 and five Pi2 alleles were observed in two breeds of Swedish horses. Complete genetic linkage was observed for Pi1 and Pi2 loci as no recombinant type was observed in 40 informative matings studied.

Genetic linkage between the loci for phosphohexose isomerase (PHI) and a serum protein (Xk) in horses

Genetic linkage between the equine loci for phosphohexose isomerase (PHI) and serum Xk protein was demonstrated by means of segregation data from three sire families. The recombination frequency was estimated from pooled data to be 0.23 +/- 0.02; a significant heterogeneity between sires for estimates of the recombination frequency was observed. No indication of linkage was detected between Xk and 14 other blood marker loci. Linkage between the Xk locus and the locus for soluble malic enzyme (ME1) has recently been reported in horses. An equine linkage group designated LG IV comprising the three loci ME1, PHI, and Xk has thus been established. The possibility that the linkage between PHI and Xk is homologous to the linkage between the loci for PHI and a serum postalbumin (PO-2) in pigs was discussed.

Two-dimensional electrophoresis of horse serum proteins: genetic polymorphism of ceruloplasmin and two other serum proteins

Two-dimensional agarose gel (pH 8.6)-horizontal polyacrylamide gel (pH 9.0) electrophoresis of horse serum proteins revealed genetic polymorphism of ceruloplasmin (Cp) and two unidentified serum proteins tentatively designated serum protein 1 (SP1) and serum protein 2 (SP2). Family data were consistent with the hypothesis that the observed Cp and SP1 phenotypes were each controlled by two codominant, autosomal alleles. The three common SP2 phenotypes were shown to be controlled by two codominant, autosomal alleles. Population data and limited family data indicated the occurrence of two additional SP2 alleles. Altogether more than 600 horses representing 13 different breeds were typed for Cp, SP1 and SP2, and allele frequency estimates were calculated. SP2 was highly polymorphic in all breeds studied whereas SP1 and Cp showed quite low degrees of polymorphism. SP1 polymorphism was observed in seven breeds while Cp polymorphism was observed only in the Icelandic toelter horse breed.

Extensive genetic polymorphism of four plasma alpha-protease inhibitors in pigs and evidence for tight linkage between the structural loci of these inhibitors

Two-dimensional horizontal gel electrophoresis of pig plasma samples (under non-denaturing conditions) using Immobiline pH gradient gels 4.0-6.0 for the first dimension separation, resulted in clear resolution of the variants of four different alpha-protease inhibitors (protease inhibitor -1 and -2, PI1 and PI2; post-albumin -1A and -1B, PO1A and PO1B). All these variants were readily visualized by general protein staining. About 900 families each of Swedish Landrace (SL) and Yorkshire (SY) breeds were studied. The extensive inheritance data, including the recombinants encountered, indicated that each of these four inhibitors is controlled by a separate, autosomal locus and that the four loci are tightly linked (spread over a distance of 1-1.5 cM) with the order as Pi1-Po1A-Po1B-Pi2. The alleles observed were two of Pi1, 14 of Po1A, 11 of Po1B and 8 of Pi2. About 40 haplotypes were observed in each of the two breeds. The allele frequencies at Po1A, Po1B and Pi2 loci were remarkably different in the two breeds; the alleles at these three loci showed a very strong linkage disequilibrium (0.8-1.0). The females showed much higher recombination frequencies than the males in the Po1A-Pi2 interval, suggesting that gene conversion-like events may be occurring at these loci. This linkage in pigs and similar ones comprising some plasma alpha-protease inhibitor genes in humans and in rodents, reported recently in the literature, indicate evolutionary conservation of a homologous linkage group in these species.

Genetic polymorphism of horse serum protein 3 (SP3)

Two-dimensional agarose gel (pH 8.6)-horizontal polyacrylamide gel (pH 9.0) electrophoresis of horse serum samples, followed by general protein staining, revealed genetic polymorphism of an unidentified protein tentatively designated serum protein 3 (SP3). The SP3 fractions appeared distinctly when a 14% concentration of acrylamide was used in the separation gels. The 2-D mobilities of SP3 fractions were quite similar to that of albumin. Family data were consistent with the hypothesis that the observed SP3 phenotypes were controlled by four co-dominant, autosomal alleles (D, F, I, S). Evidence was provided that the F allele can be further divided into two alleles (F1 and F2); the mobilities of F1 and F2 variants were very similar. Each of the SP3 alleles gave rise to one fraction and each of the heterozygous types showed two fractions. More than 600 horses representing five different breeds (Swedish Trotter, North-Swedish Trotter, Thoroughbred, Arab and Polish Tarpan) were typed for SP3, and allele frequency estimates were calculated. SP3 was highly polymorphic in all breeds studied.

Genetical control of phosphoglucose isomerase isozymes in the Japanese quail erythrocytes

Three phenotypes of phosphoglucose isomerase (PGI) from the Japanese quail erythrocytes were observed by horizontal starch gel electrophoresis. Population and family data from one laboratory population of quail was consistent with the theory that PGI polymorphism was controlled by two codominant, autosomal alleles designated PGIF and PGIS with gene frequency values 0.25 and 0.75, respectively. The study supported the earlier view that the Japanese quail is highly polymorphic with regard to biochemical variation.

Genetic polymorphism of the vitamin D binding protein and another post-albumin protein in horse serum

Horizontal polyacrylamide gel electrophoreses, on 10% separation gel, of horse serum revealed polymorphism of the vitamin D binding protein (Gc protein) and another post-albumin protein (Pa). Family data supported the hypothesis that Gc and Pa types were controlled by autosomal codominant alleles. For both Gc and Pa proteins, the homozygous types showed a single fraction while the heterozygous type had two fractions. Pa types were found to be identical to the post-albumin types reported earlier by starch gel electrophoresis. Two Gc alleles, GcF and GcS, and three Pa alleles, Pa D, Pa F and Pa S, were observed in samples from Swedish (four breeds), Lipizzaner and Arab horses. The frequency of the more common allele at the two loci, i.e. GcF and PaF, ranged from 0.72-0.93 and from 0.58-0.99, respectively, in the different breeds studied. Plasma samples showed an extra protein fraction near the GcS fraction and thus were found unsuitable for Gc typing.

Linkage between the loci for transferrin and ceruloplasmin in pigs

Evidence for genetic linkage between the loci for transferrin (Tf) and ceruloplasmin (Cp) in pigs was presented. The results were based on a study of a single sire family comprising 35 informative offspring. No recombinants were observed. The recombination frequency was estimated to be in the range of 0 to 8%. This indicated that the recombination frequency between Tf and Cp loci in pigs may be much lower than that reported previously between these two loci in cattle and in human.

Horizontal polyacrylamide gradient gel electrophoresis for the simultaneous phenotyping of transferrin, post-transferrin, albumin and post-albumin in the blood plasma of cattle

A simple method of horizontal polyacrylamide gel electrophoresis was described for the simultaneous phenotyping of transferrin, post-transferrin, albumin and post-albumin in the blood plasma of cattle. A step gradient gel of 8, 4, 12 and 14% acrylamide concentration was used. The method enabled the detection of a new protein polymorphism in the post-transferrin region. Two alleles were observed. The transferrin phenotypes involving D1 and D2 alleles were clearly separated. The resolution of the post-albumin fractions was also better than described by earlier methods.

Simultaneous phenotyping of pig plasma alpha-protease inhibitors (PI1, PO1A, PO1B, PI2) and four other proteins (PO2, TF, CP, HPX) by a simple method of 2D horizontal electrophoresis

A simple and rapid method of 2D agarose gel (pH 5.4)-horizontal polyacrylamide gel (pH 9.0) electrophoresis was developed for the simultaneous phenotyping of pig plasma alpha-protease inhibitors (protease inhibitor-1 and -2; postalbumin-1A and -1B), postalbumin-2, transferrin, ceruloplasmin and haemopexin. These eight plasma proteins were clearly visible on gels stained with Coomassie Brilliant Blue G250. The 2D patterns and mobilities of several variants of alpha-protease inhibitors were described. By using two agarose gels and 10 polyacrylamide gels, 120 samples were easily analysed in a day. Since alpha-protease inhibitors show extensive polymorphism and as the gene for postalbumin-2 is closely linked to the halothane sensitivity locus Hal, this method is a useful tool for conducting parentage control and for predicting Hal genotypes of individual pigs.

Two-dimensional electrophoresis of the plasma proteins of alpacas and llamas: genetic polymorphism of alpha 1B-glycoprotein and three other proteins

Plasma samples of alpacas and llamas were analysed by a simple method of two-dimensional (2-D) agarose gel (pH 8.6)-horizontal polyacrylamide gel (pH 9.0) electrophoresis, followed by general protein staining of gels. Genetic polymorphism in both species is described for alpha 1B-glycoprotein (alpha 1B) and three other unidentified proteins designated prealbumin (Pr), postalbumin 1 and 2 (Pa1 and Pa2). alpha 1B was identified by cross-reactivity with antisera for human and pig alpha 1B. Altogether, two alleles of Pr, two of Pa1, five of alpha 1B and three of Pa2 are described. Most of the alleles were present in alpacas and llamas. Alpacas showed a high degree of polymorphism at all four loci. Llamas showed considerable polymorphism at only the Pa1 and Pa2 loci. The theoretical probability of exclusion (PE) of an incorrectly assigned parent was estimated to be about 80% in each species by typing for the six polymorphic plasma proteins reported so far in these species. The given method of 2-D electrophoresis revealed no fixed differences in protein mobilities that discriminate between llamas and alpacas.

Polymorphic serum prealbumin (Pa) of pig, identified as and alpha1-protease inhibitor

Pig serum proteins were analysed by horizontal polyacrylamide gel electrophoresis, with a discontinuous buffer system (pH 9.0). A 12% acrylamide concentration in the separation gel was used. Each of the two paralbumin (Pa) alleles gave rise to two closely migrating fractions. The polymorphic Pa was identified as an alpha1-protease inhibitor as the Pa fractions inhibited the esterolytic activity of both bovine trypsin and chymotrypsin. Therefore, it has been proposed that the locus symbol for this prealbumin be changed to Pi-1. The protease inhibitory spectra and electrophoretic mobility of the Pa (Pi-1) fractions suggested that this protein was probably the same as the pig serum alpha1-protease inhibitor described in some earlier studies and that it corresponds to human serum alpha 1-protease inhibitor (Pi).

Polymorphic post-albumin of cattle and horse plasma identified as vitamin D binding protein (Gc protein)

Cattle and horse plasma samples of known post-albumin types were radiolabelled with 14C-vitamin D3. These samples were then analysed by polyacrylamide gel electrophoresis, followed by autoradiography. The patterns observed were identical to those of post-albumin variants. The polymorphic post-albumin protein of cattle and horse was thus identified as the vitamin D binding protein and homologous to the Gc protein of human plasma.

Parentage testing of dogs using variants of blood proteins: description of five new plasma protein polymorphisms

Plasma samples of 1126 dogs belonging to 21 different European breeds were analysed by two-dimensional agarose gel (pH 5.4 or pH 8.6)--horizontal polyacrylamide gel (pH 9.0) electrophoresis, followed by general-protein staining of gels. Genetic polymorphism was detected for five as yet unidentified proteins designated pretransferrin-1 and -2 (Prt1 and Prt2) and postalbumin-1, -2 and -3 (Pa1, Pa2 and Pa3). Three alleles are reported in the Prt1 and Prt2 systems and two alleles in the Prt2, Pa1 and Pa3 systems. While Prt2 variation was observed only in the cocker spaniel breed, each of the other four proteins showed a high degree of polymorphism in most of the breeds studied. Pa3 fractions were clearly observed only in samples stored at -20 degrees C for more than 2 years. Prt1, Pa1 and Pa2 proteins are additional useful markers for parentage control in dogs. This study corroborated previously published results that dog plasma proteins, in general, show considerably more polymorphism than that reported for haemoglobin and for several blood cell enzymes in this species.

Further data on chromosomal assignments of pig enzyme loci LDHA, LDHB, MPI, PEPB and PGM1, using somatic cell hybrids

Clear interspecies differentiation between the chromosomes in pig-mouse somatic cell hybrids was achieved by using the THA-technique for the cytogenetic analysis. The assignments of LDHB and MPI to pig chromosomes nos 5 and 7 respectively, reported previously, were confirmed by analysis of 34 hybrid clones. The LDHA, PEPB and PGM1 genes were assigned to pig chromosomes nos 2, 5 and 6 respectively. Both LDHB and PEPB were indicated to be located on the long arm, except the most proximal part, of pig chromosome no. 5. The proposed synteny between LDHB and PEPB in pigs is in accordance with the synteny observed between these two loci in several other mammalian species.

Prediction of the halothane (Hal) genotypes of pigs by deducing Hal, Phi, Po2, Pgd haplotypes of parents and offspring: results from a large-scale practice in Swedish breeds

Results from a large-scale study, comprising 75 different breeding herds, are reported on predicting the halothane (Hal) genotypes of individual pigs by making use of the known close linkage between Hal and three electrophoretic blood marker loci (Phi, Po2, Pgd). The parents haplotypes (involving Hal and marker loci) were determined from the HAL phenotypes (halothane test results) and marker loci phenotypes of their offspring in the first one or two litters studied. In subsequent litters of the Hal-marker loci haplotyped parents, the offspring's expected Hal genotypes could be predicted on the basis of the marker loci haplotypes inherited by them. By comparing the expected and observed HAL phenotypes of offspring in subsequent litters, the predicted Hal genotype was found to be correct in 90-95% of the 4000 offspring (from Nn X Nn and Nn X nn matings) of Swedish Landrace and Yorkshire breeds studied. The order of the three marker loci was confirmed as Phi-Po2-Pgd but the position of Hal with regards to Phi could not be resolved. The recombination frequencies between the most distant loci in this region, viz. Hal-Pgd and Phi-Pgd, were estimated to be 3-4.5% and 4-6%, respectively. The easy and rapid electrophoretic techniques described in the study to phenotype PHI, PO2, PGD, also allowed phenotyping of six other polymorphic protein systems on the same gels. Thus Hal genotyping and effective parentage control can be conducted simultaneously.

Genetic polymorphism of plasma alpha 1 B-glycoprotein and transferrin in arctic and silver foxes

Plasma samples of 235 foxes from 38 complete families (14 of arctic foxes, 21 of silver foxes and 3 with arctic x silver fox hybrid offspring) were analysed by one-dimensional horizontal polyacrylamide gel electrophoresis (PAGE) pH 9.0 followed by general-protein staining of gels. A major postalbumin of fox plasma was identified as alpha 1B-glycoprotein (alpha 1B) by using immunoblotting with antiser m specific to human or pig plasma alpha 1B. Four codominant, autosomal alleles of alpha 1B were found in arctic foxes. Two transferrin (TF) alleles (TfF, TfS) were observed in arctic foxes and two (TfD, Tff) in silver foxes; the TF F type of both of the fox species showed identical electrophoretic mobilities. The arctic foxes showed a high degree of polymorphism for both TF and alpha 1B. The silver foxes showed a scarce polymorphism of TF and were monomorphic for alpha 1B. The arctic fox, silver fox and their hybrids could be clearly differentiated from one another by their plasma protein patterns obtained by the PAGE method.

Further data on adenosine deaminase polymorphism in pigs and evidence for a new allele

Evidence was provided for a new erythrocyte ADA allele (Aw) in the Swedish Landrace breed of pigs. The enzyme activity of Aw variant was considerably less than that of the previously reported erythrocyte ADA variants A and B. The mobility of the Aw variant was identical to that of the A variant, both by electrophoresis and by isoelectric focusing. The in vitro heat stability (at 56 degrees C) of the Aw variant was similar to that of A and B variants. The leucocyte ADA activity was normal in pigs with the erythrocyte ADA Aw variant. The frequencies of the erythrocyte ADA alleles, A, B, Aw, and O (silent allele) in four breeds of pigs in Sweden were: Landrace--0.51, 0.19, 0.11, 0.19; Large White--0.91, 0.03, 0.0, 0.06; Duroc--0.95, 0.05, 0.0, 0.0; Hampshire--0.12, 0.14, 0.0, 0.74.

Three new plasma protein polymorphisms in domestic foxes, detected by a simple method of 2D horizontal electrophoresis

Plasma samples of 270 foxes from 45 complete families (14 of arctic foxes, 28 of silver foxes and 3 with arctic x silver fox hybrid offspring) were analysed by a method of two-dimensional agarose gel (pH 5.4)-horizontal polyacrylamide gel (pH 9.0) electrophoresis followed by general-protein staining of gels. Genetic polymorphism of three plasma proteins, tentatively designated prealbumin (Pr), postalbumin 1 (Pa1), and pretransferin 1 (Prt1), was observed. In silver foxes, Pa1 and Prt1 showed a high degree of polymorphism, each with 3 common alleles, while Pr showed a scarce polymorphism. The arctic foxes were monomorphic for Pr and Prt1 and showed a scarce Pa1 polymorphism. The Prt1 phenotype of arctic foxes showed identical mobility with one of the Prt1 variants of silver foxes.

Detection of the causal mutation for canine leukocyte adhesion deficiency (CLAD) using pyrosequencing

A missense mutation in the ITGB2 gene causes canine leukocyte adhesion deficiency (CLAD) in Irish setters. We constructed a diagnostic test to identify heterozygous CLAD carriers based on a newly developed technology termed pyrosequencing. Although primarily designed for high-speed generation of DNA sequence in a gel-free system, the technology can be applied to rapid single-nucleotide polymorphism analysis in a clinical setting. The testing of 339 dogs originating from a total of 10 countries was conducted and CLAD carriers were identified within every country where more than one sample was analysed. This indicates that the CLAD mutation is widespread and that there is a strong need for a robust diagnostic test.

A missense mutation in the beta-2 integrin gene (ITGB2) causes canine leukocyte adhesion deficiency

Canine leukocyte adhesion deficiency (CLAD) is a fatal immunodeficiency disease found in Irish setters. The clinical manifestations of CLAD are very similar to LAD in humans and BLAD in cattle, which are both caused by mutations in ITGB2 encoding the leukocyte integrin beta-2 subunit (CD18). Sequence analysis of the ITGB2 coding sequence from a CLAD dog and a healthy control revealed a single missense mutation, Cys36Ser. This cysteine residue is conserved among all beta integrins, and the mutation most likely disrupts a disulfide bond. The mutation showed a complete association with CLAD in Irish setters and was not found in a sample of dogs from other breeds. The causative nature of this mutation was confirmed by transduction experiments using retroviral vectors and human LAD EBV B-cells. The normal canine CD18 formed heterodimers with the human CD11 subunit, whereas gene transfer of the mutant CD18 resulted in very low levels of CD11/CD18 expression. The identification of the causative mutation for CLAD now makes it possible to identify carrier animals with a simple diagnostic DNA test, and it forms the basis for using CLAD as a large animal model for the development and evaluation of clinical treatments for human LAD.

Genetic markers linked to neuronal ceroid lipofuscinosis in English setter dogs

The neuronal ceroid lipofuscinoses (NCL) are a group of fatal autosomal recessive neurodegenerative diseases occurring in human and some domesticated animal species. A canine form of the disease (CNCL) has been extensively studied in a Norwegian colony of inbred English setters since 1960. A resource family developed for genetic mapping and comprising 170 individuals was typed for 103 genetic markers. Linkage analysis showed three genetic markers to be linked to the disease locus with the closest marker at a distance of about 3 CM. Two other loci were linked with these markers making a linkage group of five genetic markers. The linkage group spanned a distance of 54 CM. Two genes for human forms of the disease, CLN2 and CLN3, have been identified and mapped to human chromosome 11p15 and 16p12, respectively. The present study did not indicate any linkage between CNCL and the canine CLN3 homologue or to homologues of markers for genes that map close to human CLN2.

A comprehensive linkage map of the pig based on a wild pig-Large White intercross

A comprehensive linkage map, including 236 linked markers with a total sex-average map length of about 2300 cM, covering nearly all parts of the pig genome has been established. Linkage groups were assigned to approximately all 18 autosomes, the X chromosome and the X/Y pseudoautosomal region. Several new gene assignments were made including the assignment of linkage group U1 (EAK-HPX) to chromosome 9. The linkage map includes 77 types I loci informative for comparative mapping and 72 in situ mapped markers physically anchoring the linkage groups on chromosomes. A highly significant heterogeneity in recombination rates between sexes was observed with a general tendency towards an excess of female recombination. The average ratio of female to male recombination was estimated at 1.4:1 but this parameter varied between chromosomes as well as between regions within chromosomes. An intriguing finding was that blood group loci were overrepresented at the distal ends of linkage groups.

Relationship between parental cardiac status in Cavalier King Charles spaniels and prevalence and severity of chronic valvular disease in offspring

OBJECTIVE

To study the relationship between parental cardiac status in Cavalier King Charles Spaniels and development of chronic valvular disease (CVD) in offspring.

DESIGN

Historical cohort.

ANIMALS

54 female and 53 male Cavalier King Charles Spaniel offspring.

PROCEDURE

7 sires, selected on the basis of their liability to develop CVD, were screened for clinical signs of CVD and assigned to 1 of 3 groups (late, intermediate, and early onset of CVD). The mates of these sires (30 dams) were selected and classified likewise, and 107 offspring produced in 1988 from matings between these parents were screened for clinical signs of CVD at a mean age of 5.3 +/- 0.3 years.

RESULTS

55% of the offspring were free from clinical signs of CVD, whereas 45% had cardiac murmurs of low or moderate intensity. The proportion of offspring with heart murmurs and the intensity of murmurs were significantly greater with increased parental classification. More males than females had developed murmurs, and murmurs of moderate intensity also were more prevalent in males. Results of multiple-regression analysis indicated that mean parental classification and sex had significant effects on proportion of offspring with murmurs and their intensity. Additionally, age affected disease prevalence and severity, despite the narrow range in age of offspring examined.

CLINICAL IMPLICATIONS

Parental CVD status is an important factor influencing the probability of heart murmurs and their intensity in offspring. The results of this study indicate that CVD development is a polygenic threshold trait and that sex of the offspring influences threshold levels.

A major locus (RN) affecting muscle glycogen content is located on pig chromosome 15

The RN locus in pigs has a major effect on the amount of stored glycogen in white muscle and affects meat quality. The fully dominant RN- allele, associated with high glycogen content, occurs in the Hampshire breed. We have mapped the RN locus using a large half-sib family comprising one heterozygous RN-/rn+ Hampshire boar mated to homozygous rn+/rn+ Swedish Landrace x Swedish Yorkshire sows. The segregation at the RN locus was inferred from data on glycolytic potential and residual glycogen in white muscle which both showed clear bimodal distributions. Highly significant evidence for genetic linkage was obtained against microsatellite markers on Chromosome (Chr) 15. Multipoint analysis revealed the order Sw1111-8.0-S0088-10.6-RN-4.8-Sw936,Sw906 (recombination estimates are given as Kosambi cM). Comparative mapping data imply that the human homolog of RN is located on Chr 2q.

The porcine intestinal receptor for Escherichia coli K88ab, K88ac: regional localization on chromosome 13 and influence of IgG response to the K88 antigen

The loci encoding the porcine intestinal receptors for Escherichia coli K88ab and K88ac (K88abR and K88acR) were firmly assigned to chromosome 13 by linkage analysis using a three-generation pedigree. The linear order of these loci and seven other markers on chromosome 13 was determined by multipoint analyses. The K88abR and K88acR loci were tightly linked (theta = 0.01, zeta = 41.06) with the K88abR locus localized 7.4 cM (sex average) proximal to the transferrin locus. The results, together with previous reports from two other groups, provide an unequivocal assignment of the K88 receptor loci to chromosome 13, and reject a previous assignment to chromosome 4. Pigs possessing the receptor had a slightly higher specific IgG response to the K88 antigen after an intramuscular immunization with an E. coli vaccine.

Genetic variation at pig plasma protein locus PLP1 and its assignment to chromosome 5

A new genetic polymorphism of an unidentified plasma protein (PLP1) in pigs was described by using a method of two-dimensional gel electrophoresis and protein staining. Two codominant alleles, with frequencies of 0.83 and 0.17, were found in the Swedish Yorkshire breed. The PLP1 marker was typed in a three-generation pedigree and tested for linkage against a set of 128 markers. The PLP1 locus showed significant LOD score values with three different microsatellite markers (S0092, DAGK and S0005), previously assigned to chromosome 5.

Distribution of plasma alpha-1-B-glycoprotein (A1BG) polymorphism in several populations of the Indian subcontinent

The distribution of plasma alpha 1B-glycoprotein (A1BG) was determined by a two-dimensional electrophoresis (agarose-polyacrylamide gel) followed by protein staining in a group of 1099 individuals from 11 populations of the Indian subcontinent. The sample comprised 454 from several tribes of Arunachal Pradesh; 76 Bengali Hundus and 88 Bengali Muslims; 179 Tamil Hindus from Singapore and 107 from India; 81 Tamil Muslims, 48 Sinhalese from Sri Lanka and 66 North Indians. Three common A1BG phenotypes (1-1, 1-2 and 2-2) were observed in this study. One each of a new allele (A1BG*7) in heterozygous form (1-7) was detected respectively among Tamil Hindus of India and Singapore. The phenotypic distribution of A1BG alleles was at Hardy-Weinberg equilibrium in all the populations. The frequency of A1BG*2 was in general lower in the Mongoloid tribes of Arunachal Pradesh (0.043-0.104) and North Indians (0.068) compared to that in other Indian populations (0.130-0.171) and Sinhalese (0.208).

Assignment of 20 microsatellite markers to the porcine linkage map

Twenty-one porcine microsatellite markers were developed by screening DNA libraries and by a computer search of databases. The microsatellites were typed in a large three-generation family established by a cross between the European wild pig and a Swedish Yorkshire breed. Linkage analysis benefited from the fact that due to the divergence between the parental populations, the degree of microsatellite polymorphism was significantly higher in the F1 animals than in either of the parental populations. Parallel typing of a set of 35 restriction fragment length polymorphism, protein, and blood group markers rendered it possible to assign as many as 20 of the microsatellites to the porcine linkage map. Fourteen microsatellites were localized to a chromosome segment, whereas six constituted parts of unassigned linkage groups. Analysis of four microsatellites within genes allowed the assignment of the endoplasmic reticulum Ca2+ transport ATPase locus to chromosome 14, the assignment of the interferon-gamma and the diacylglycerol kinase loci to a new linkage group (XI), and the localization of the tumor necrosis factor beta locus close to the major histocompatibility complex (SLA) on chromosome 7 to be confirmed. Fluorescence in situ hybridization mapping of two microsatellite-containing cosmids assigned two linkage groups to chromosomes 9 and 12, respectively. In total, 27 new markers were added to the porcine linkage map, thereby almost doubling the number of markers on the map. Linkage groups are now present on 10 of 18 of the pig autosomes.(ABSTRACT TRUNCATED AT 250 WORDS)