Characterisation of the alpha 1-protease inhibitor system in Thoroughbred horse plasma by horizontal two-dimensional (ISO-DALT) electrophoresis. 1. Protein staining

In slow pace towards the proteome of equine body fluids

Equine medicine represents a relevant field of veterinary science and the horse industry generates a significant economic impact. Horses can be involved in different sport disciplines, meat production, work and recreational purposes. Horses are also important for human health as they can be used as animal models for studying human diseases and in equine-assisted therapy. This review summarizes the data related to body fluids such as plasma/serum, urine, cerebrospinal fluid, synovial fluid, saliva, bronchoalveolar lavage fluid and peritoneal fluid obtained using proteomic analysis. Horse body fluid proteome analysis under various physiological and pathological conditions is a useful method for identifying new biomarkers for horse diseases which are still difficult to diagnose, but with serious consequences on equine health and welfare. The findings reported here reveal that further proteomic studies on equine body fluids collected from diseased animals are required. SIGNIFICANCE: Body fluids are sources of potential protein biomarkers for diagnosis and therapeutic target identification. Indeed, they contain proteins that play a crucial role in cell functions and whose presence or relative abundance are indicative of the health status of tissues/organs. The review reports the data on the equine body fluids obtained using proteomic analysis, including those which are commonly used to obtain a correct diagnosis and prognosis of horse diseases which still pose a significant challenge. For equine medicine, new biomarkers are needed to formulate early diagnosis and to distinguish among diseases with similar clinical signs.

Brahman bull fertility in a north Australian rangeland herd

Low and variable bull fertility was identified as a constraint on reproductive rates in beef cattle grazed in an extensive, multiple sire mating regimen on Mount Bundey station in the Darwin pastoral district of northwestern Australia. Erratic conception patterns were attributed to a high proportion of bulls with low breeding soundness evaluation scores (BSE), a high proportion of aged bulls (40%>8 yr), and to running bulls of mixed age groups. Liveweight, scrotal circumference (SC) and age were positively correlated. An experiment was subsequently designed to investigate the ability of a number of bull measurements to predict fertility in an extensively-managed, multiple-sire mating system. Blood typing was used to match calves to sires. It proved to be an accurate and useful technique which successfully identified the parentage of 94% of calves examined. Single measurements of serum testosterone after administration of gonadotrophin-releasing hormone (GnRH) were not correlated with fertility. However six of the seven most fertile bulls exhibited high peak serum testosterone levels in summer, and lower levels in the winter. In contrast, the less fertile bulls did not exhibit seasonal variation in GnRH-induced serum testosterone levels. Social dominance ratio was weakly related to fertility (r=0.51: P<0.05). BSE (r=0.51: P<0.05) and SC (r=0.49: P<0.05) prior to, but not subsequent to, mating were correlated with bull fertility. Under the conditions of this experiment, a bull to cow ratio of 1:20 was excessive for bulls with a satisfactory BSE score.

Genetic polymorphism of plasma vitamin D-binding protein (GC) in Australian goats

Polymorphism at the GC locus in goats was detected using isoelectric focusing (pH 4.5-5.4) and immunoblotting with antiserum to human GC. Three variants, designated A, B and C in order of decreasing mobility to the anode, were detected and were shown to be controlled by three codominant alleles, GCA, GCB and GCC. GCA and GCB occurred in all four breeds (Australian and Texan Angora, Cashmere and Dairy) with GCA being the most common and having gene frequencies ranging from 0.851 to 0.993. GCC was found only in Australian Angora and Cashmere animals. The products of the three GC alleles had isoelectric points in the range pH 4.63-4.95 and M(r) of approximately 54,375. The major isoforms of the three alleles were shown to contain sialic acid. Linkage between the GC and albumin loci was unable to be demonstrated due to the low frequency of ALBA (0.02) in the Cashmere breed.

Relationships between the bovine major histocompatibility system and commonly recognized erythrocyte and serum polymorphisms

Linkage at a recombination frequency of 0.10 or less between the bovine major histocompatibility system and the B, C and L red blood cell groups and the albumin, haemoglobin and transferrin loci was excluded by Morton's lod score method. The white blood cell antigen CA19, which is independent of the bovine major histocompatibility system, is the J blood group.

Frequencies of plasma protease inhibitor alleles in Australian horse breeds and the recognition of two new alleles

Investigation of the plasma protease inhibitor system (Pi) in the Arabian and quarter horse breeds and re-examination of the standardbred breed resulted in the recognition of two new Pi alleles, designated E and L2. PiE is rare and has been found in only three quarter horses. In contrast, PiL2 is relatively common in the standardbred (0.107) and allowed subdivision of PiL into PiL and PiL2. Splitting of PiL resulted in an exclusion probability (PE) of 0.649 for the standardbred Pi system. Frequencies of the Pi genes have now been determined for four breeds (thoroughbred, standardbred, quarter horse and Arabian) of horses in Australia.

ISO-DALT characterization of 12 'new' equine plasma protease inhibitor (Pi) alleles

Twelve equine protease inhibitory alleles, PiE, H, J, K, L2, O, P, Q, R, V, X, Z, have been characterized in terms of isoelectric point, molecular mass and inhibitory activity to bovine trypsin and chymotrypsin by ISO-DALT electrophoresis. Protein maps for 20 Pi alleles including those of the eight 'Thoroughbred' alleles (PiF, G, I, L, N, S1, S2, U) have now been determined. Five pairs of alleles, S1/S2, G/K, L/L2, P/R and U/Z, possessed varying numbers of common proteins ranging from one protein in the case of G/K and L/L2 to six in the case of U/Z. Based on these results and studies of the abnormal expressions of PiF, PiL and PiS1, a theory of at least three closely linked loci has been postulated to account for the marked heterogeneity of the equine protease inhibitory system.

The plasma protease inhibitor system (Pi) of Standardbred horses

The plasma protease inhibitor system (Pi) of Standardbred horses was studied by thin-layer, high-voltage, acid polyacrylamide gel electrophoresis (pH 4.6) followed by protein staining and staining for trypsin and chymotrypsin inhibition. In addition to the eight Thoroughbred alleles (PiF, G, I, L, N, S1, S2, U), another 10 alleles, designated PiH, J, K, O, P, Q, R, V, X, Z, were postulated to account for the 98 Pi types which were observed in Standardbreds. Detailed inhibitory spectra of the 'new' alleles were determined and further exceptions to the Pi1, Pi2 classification of Juneja et al. (1979) were found. Limited family data demonstrated the genetic nature of the 'new' variants and confirmed the allelic inheritance of the 'new' Pi variants.

Characterisation of the alpha 1-protease inhibitor system in Thoroughbred horse plasma by horizontal two-dimensional (ISO-DALT) electrophoresis. 2. Protease inhibition

The protease inhibitory spectra of the eight homozygous Thoroughbred Pi types against trypsin, elastase and chymotrypsin have been determined. The alpha 1-protease inhibitor proteins exhibit three classes of inhibitory specificity towards these enzymes. The Pi types F, I, N and U exhibit class I (trypsin, elastase and chymotrypsin) and class II (trypsin and elastase) types of inhibition and fit Juneja et al.'s (1979) classification of two separate genetic systems Pi 1 and Pi 2 based on differences in the inhibitory spectra against trypsin and chymotrypsin. The remaining four Pi types are exceptions to Juneja et al.'s (1979) classification. Types G, L, S1 and S2 possess class I but not class II proteins. A third class of proteins (class III) which exclusively inhibit chymotrypsin was detected in all eight protease inhibitor types. Type G is well represented by class III proteins because two of the three major proteins of the ISO-DALT pattern inhibit only chymotrypsin and is thus an exception to Juneja et al.'s (1979) classification.

Subdivision of equine Tf into H1 and H2

Subdivision of equine TfH into two variants, designated H1 (faster) and H2 (slower), has been accomplished by high voltage, thin layer polyacrylamide gel electrophoresis at pH 7.9. Transferrin H1 and H2 have been shown to be controlled by codominant alleles and gene frequencies of the Tf alleles have been determined in the Australian Thoroughbred, Standardbred. Quarter Horse and Arabian Horse breeds.

A new genetic variant Z2 in the Pi system of horses

A new genetic variant in the horse Pi system, designated Z2, was reported in Polish Arabs by using two-dimensional agarose polyacrylamide gel electrophoresis. The frequencies of Pi alleles F, G, L, L2, N, S, U, W, Z and Z2 were found to be 0.036, 0.005, 0.171, 0.013, 0.008, 0.237, 0.416, 0.003, 0.107 and 0.004 respectively.

First-generation linkage map of the gray, short-tailed opossum, Monodelphis domestica, reveals genome-wide reduction in female recombination rates

The gray, short-tailed opossum, Monodelphis domestica, is the most extensively used, laboratory-bred marsupial resource for basic biologic and biomedical research worldwide. To enhance the research utility of this species, we are building a linkage map, using both anonymous markers and functional gene loci, that will enable the localization of quantitative trait loci (QTL) and provide comparative information regarding the evolution of mammalian and other vertebrate genomes. The current map is composed of 83 loci distributed among eight autosomal linkage groups and the X chromosome. The autosomal linkage groups appear to encompass a very large portion of the genome, yet span a sex-average distance of only 633.0 cM, making this the most compact linkage map known among vertebrates. Most surprising, the male map is much larger than the female map (884.6 cM vs. 443.1 cM), a pattern contrary to that in eutherian mammals and other vertebrates. The finding of genome-wide reduction in female recombination in M. domestica, coupled with recombination data from two other, distantly related marsupial species, suggests that reduced female recombination might be a widespread metatherian attribute. We discuss possible explanations for reduced female recombination in marsupials as a consequence of the metatherian characteristic of determinate paternal X chromosome inactivation.

Improved hepatic and pancreatic localisation of the equine alpha-1-proteinase inhibitor family of serpins using an antigen enhancement technique and a monoclonal antibody

Equine alpha-1-proteinase inhibitor (API) consists of three, occasionally four, serum glycoproteins. This study investigated the immunohistochemical localisation of equine API in paraformaldehyde fixed, paraffin embedded equine tissue samples of liver, lung, stomach, pancreas, jejunum and colon in five horses using affinity purified sheep polyclonal and protein A purified mouse monoclonal antibodies, whose specificities were verified by Western blotting. Exposing tissue sections to boiling citrate buffer greatly enhanced antigen recovery and improved immunostaining with both antibodies, resulting in discovery of novel tissue distribution patterns for the horse. In the horses studied, all hepatocytes showed some degree of cytoplasmic staining, many having perinuclear intense granular inclusions. This finding is contrary to findings in human studies where hepatocytes of Pi MM phenotype have proven difficult to stain for human API, despite evidence at the molecular level suggesting hepatocytes as the major source of serum API. This discrepancy may be due to the use of different tissue fixation and antigen recovery techniques. In all other tissues examined, the distribution of equine API was similar to human studies.

Plasma protease inhibitor (PI) system in the laboratory opossum, Monodelphis domestica

Protease inhibitor (PI) polymorphism was observed in the laboratory opossum, Monodelphis domestica, by either one-dimensional acid polyacrylamide gel electrophoresis (PAGE; pH 4.6) or isoelectric focusing (pH 3.5-5.0) followed by immunoblotting with rabbit antiserum to human alpha 1-antitrypsin; but acid PAGE produced superior resolution of the PI proteins. Family studies demonstrated an inheritance of nine codominant autosomal alleles, PID, PIE, PIF, PIG, PIH, PII, PIJ, PIK, and PIM, and a population study revealed frequencies of 0.411, 0.010, 0.341, 0.034, 0.023, 0.071, 0.035, 0.020, and 0.055, respectively.

Molecular weight alterations of alpha-1 proteinase inhibitor in equine bronchoalveolar lavage fluid

The equine alpha-1 proteinase inhibitor (alpha 1PI) system differs from that of man in that the equine system consists of four closely-linked genes (Spi1-Spi4) whereas in man, a single gene encodes for alpha 1PI. We have previously found differences in the proportion of the Spi proteins in equine serum and bronchoalveolar lavage fluid (BALF). We therefore wished to determine whether, as reported in man, there was any molecular weight difference between the Spi proteins in serum and BALF. alpha 1PI and albumin from equine BALF migrated further towards the anode compared with serum alpha 1PI on native polyacrylamide gel electrophoresis (PAGE) although the difference was only significant for alpha 1PI. Sodium dodecyl sulphate-PAGE (SDS-PAGE) showed that a mean decrease in molecular weight of 1.5 kDa for alpha 1PI and 1.3 kDa for albumin had occurred in BALF. These findings were observed in control animals and in those with symptomatic or asymptomatic chronic obstructive pulmonary disease. The mechanism of this decrease in molecular weight of alpha 1PI is likely to differ from reports of alpha 1PI cleavage by bacterial proteinases in man since the molecular weight change was relatively small and loss of trypsin inhibitory activity did not occur. Nor, in our system, was there evidence of bacterial infection. Damage by endogenous proteinases or glycosidases at a site other than the reactive site may be involved but the resultant effect on the efficiency of the antiproteinase screen of the lower respiratory tract is uncertain.

Equine plasminogen polymorphism: allelic frequencies in 23 breeds

A modified procedure for detection of the two alleles of equine plasminogen using Western blotting methods following polyacrylamide gel isoelectric focusing is described. Gene frequencies in 23 breeds and Equus przewalskii are provided.

Comparative studies of the Spi1 proteins of three equine alpha-1-proteinase inhibitor haplotypes following isolation by affinity chromatography

1. Antiproteinase deficiency can result in excessive proteinase-induced tissue damage. The major anti-elastase (Spi1) protein of equine alpha 1-proteinase inhibitor (alpha 1-PI) was isolated from the plasma/serum of three common haplotypes (I, L and U). 2. The N-terminal amino acid sequences of the three inhibitors were identical, but were only approx 65-77% homologous with two other published equine Spi1 sequences. 3. All three inhibitors complexed quickly and irreversibly with equine leucocyte proteinase 2A (kass = 2 x 10(7) M-1 sec-1). They were also efficient inhibitors of chymase (rat mast cell proteinase-II; kass = 2 x 10(5) M-1 sec-1; Ki = 2 x 10(-10) M). There was therefore no evidence of deficient inhibition in the Spi1 variants of the I,L and U haplotypes.

Caprine plasma proteinase inhibitors--I. Partial characterization

1. Using two-dimensional electrophoresis (IEF, pH 3.5-6.0 and PAGE, 11.5% T, pH 7.9) the caprine plasma proteinase inhibitors were classified into six distinct classes, designated PIA, PIB, PIC, PID, PIE and PIF. Differentiation of the six inhibitors was based on electrophoretic criteria, their abilities to inhibit bovine trypsin and chymotrypsin and their crossreactions with antisera to human alpha 1-antitrypsin and alpha 1-antichymotrypsin. 2. Polymorphic variants were identified for five of the protein systems (PIA, PIB, PIC, PID and PIE) and the electrophoretic data indicated that the variants were controlled by allelic genes. PIF proteins were poorly resolved and invariant. 3. Treatment of selected plasmas with neuraminidase demonstrated that the microheterogeneity observed in the PIA, PIB, PIC and PID proteins was attributable to sialic acid additions. 4. The inhibitory activities of all six caprine proteinase inhibitors were unaffected by chemical oxidation with chloramine-T.

The equine major plasma serpin multigene family: partial characterization including sequence of the reactive-site regions

The equine Pi system, which is highly polymorphic and was considered to be controlled by a single locus, has been shown to be controlled by four loci (named Spi 1-4). This system is the equine equivalent of the major human plasma serpin (serine protease inhibitor), human alpha 1 PI. Twenty-two haplotypes of the equine Pi system have been characterized by two-dimensional electrophoresis, resulting in the assignment of pI, Mr, and bovine trypsin and chymotrypsin inhibition characteristics to 109 proteins. These proteins have been analyzed further to determine their relatedness to each other as well as to human alpha 1 PI using immunochemical, structural, and functional criteria. The amino acid sequences of the N termini and reactive-site regions have been determined on proteins from each of the four equine Spi loci. This allowed the designation of the proteins from the Spi 1 locus as being METserpins and the functional equivalents of human alpha 1 PI. The Spi 4 proteins are ARGserpins, and by alignment the Spi 2 proteins are ILEserpins, the first so far described. The P1 residue for the Spi 3 proteins was unable to be determined. The limited peptide and immunopeptide mapping revealed that proteins from all four loci were closely related, but within the four there were two pairs (Spi 1 and 2 and Spi 3 and 4) which were more related. All were probably derived from the same gene that gave rise to human alpha 1 PI.

Comparative properties of three functionally different but structurally related serpin variants from horse plasma

Three structurally related but functionally different serpins from horse plasma were isolated and characterized. In spite of their identical N-terminal sequences, which show some similarity to that of human alpha 1-proteinase inhibitor, the reactive-centre loops of each of these proteins show extensive variation. Only inhibitor I, with a P1 methionine residue, resembles human alpha 1-PI with regard to (a) similarity of amino acid sequence in the vicinity of the reactive-site peptide bond, (b) broad inhibitory specificity, (c) sensitivity to oxidative inactivation and (d) high rate of reactivity with neutrophil elastase(s). Inhibitor II, with a P1 arginine residue, is an exclusive trypsin inhibitor, and inhibitor III is an oxidation-resistant slow-reacting elastase inhibitor with a P1 alanine residue. Comparison of association rate constants for the inhibition of horse neutrophil elastases by the three inhibitors indicates that only inhibitor I is likely to be physiologically important in the regulation of these enzymes.

Mammalian alpha 1-antitrypsins: comparative biochemistry and genetics of the major plasma serpin

1. Human alpha 1-antitrypsin (alpha 1 AT) has been extensively characterized and reviewed. It is the archetypal member of the superfamily of serine proteinase inhibitors, the serpins. As human alpha 1-antitrypsin exhibits a relatively high concentration in plasma and is usually the highest concentration serpin, it can be referred to as the major plasma serpin. 2. alpha 1-Antitrypsin from species other than man has been characterized for two major reasons: (1) for use in a model animal system to assist with the study of the human alpha 1 AT deficiency disease; and (2) to find polymorphism for use in gene mapping and linkage studies or for parentage analysis. 3. The diverse range of reasons for studying alpha 1AT has yielded a vast array of literature that is often not well cross-referenced. 4. The characteristic features of alpha 1AT in all species examined to date will be presented with a view to examining which features are important structurally and functionally from an evolutionary perspective. 5. In mouse, horse, rabbit and guinea pig, multigene families which appear to have arisen from alpha 1AT have been found. The functional and evolutionary implications of these paralogous genes will also be discussed.

Fibrinolysis as a feature of disseminated intravascular coagulation (DIC) after Pseudonaja textilis textilis envenomation

Blood was obtained from four patients envenomated by the Australian common brown snake, Pseudonaja textilis textilis. This elapid snake has one of the most toxic venoms in the world, containing extremely potent neurotoxic and coagulant components. The latter is a potent complete prothrombinase, converting prothrombin to alpha-thrombin, and comprises more than 30% of the total venom protein. The four envenomated patients developed a typical consumption coagulopathy. Serial serum and plasma samples from patients were studied by immunoaffinity adsorption, 2-alanine precipitation of fibrinogen and fibrinogen-related products and 2-dimensional immunoelectrophoresis, and assayed for crosslinked fibrin degradation products as D dimer, using the monoclonal antibody, DD-3B6/22. These procedures showed the virtually complete disappearance of fibrinogen, accompanied by the appearance of large quantities of fibrinogen and fibrin degradation products consisting of both crosslinked and noncrosslinked species. With recovery, a homogeneous high molecular weight fibrinogen was observed. The data suggest that the prothrombin activator of this venom causes the generation of thrombin which subsequently converts fibrinogen to fibrin and stimulates partial crosslinking of both alpha and gamma-chains. The resultant disseminated intravascular coagulation is accompanied by very active secondary fibrinolysis which apparently limits the extent of any microvascular thrombosis but which may contribute to a bleeding tendency.

Equus przewalskii plasma protease inhibitor (Pi) system

A detailed biochemical characterization of four of the five previously described alleles of the plasma protease inhibitor (Pi) system of Equus przewalskii was performed using both one- and two-dimensional electrophoretic techniques. The proteins have been characterized in terms of isoelectric point, relative molecular mass, inhibitory activity to bovine trypsin and chymotrypsin, immunochemical cross-reactivity, terminal sialic acid content and enzyme:inhibitor complex formation and the oxidation sensitivity of this interaction. Using these functional criteria, only three loci (Spi 1, 2 and 3) were found to control the plasma Pi proteins of the E. przewalskii haplotypes. In contrast a fourth locus, Spi 4, was found in some E. caballus haplotypes. The significance of these results with respect to the complexity of the protein pattern exhibited by the equine Pi multigene family is discussed.

Feline whey proteins: identification, isolation and initial characterization of alpha-lactalbumin, beta-lactoglobulin and lysozyme

1. Both alpha-lactalbumin and beta-lactoglobulin-like proteins were detected in the whey fraction of feline milk by immunoblotting with rabbit antisera to alpha-lactalbumin and beta-lactoglobulin, respectively. 2. alpha-Lactalbumin was found to occur in both glycosylated and unglycosylated forms in approximately equal concentrations. No polymorphism of feline alpha-lactalbumin was found. 3. Feline beta-lactoglobulin-like proteins produced complex electrophoretic patterns that appear to be determined by three distinct loci. Between two and five genetic variants are expressed by each locus. 4. Lysozyme was detected at levels of approximately 1 mg/ml in skim milk. 5. The identifications of the proteins as alpha-lactalbumin, beta-lactoglobulin and lysozyme were confirmed by determination of N-terminal amino acid sequences.

An improved method for the study of equine haptoglobin heterogeneity

Equine serum haptoglobin was separated by polyacrylamide gel isoelectric focusing and visualized by protein staining or Western blotting. Conventional protein staining revealed up to three bands in the pI range 4.17 to 4.44. The blotting technique, however, showed an anodal group of 8 to 10 bands with a pI range of 4.11 to 4.52 and a cathodal group of 4 to 6 bands with a range of 4.55 to 5.14. The blotting method revealed that equine haptoglobin migrates outside the prealbumin area, in contrast to previous reports.

Genetic linkage between loci for a red cell alloantigen (U) and serum protease inhibitor (Pi) in the horse

Preliminary evidence for the fifth autosomal linkage group in the horse, comprised of the loci for a red cell alloantigen (U) and serum protease inhibitor (Pi), was demonstrated by means of paternal half-sib groups in thoroughbred, standardbred and Arabian breeds. Recombination frequency in males was estimated to be 0.125 +/- 0.019.