Codominant Alleles Research Articles

Genetic polymorphisms of the CST2 locus coding for cystatin SA

A new genetic polymorphism of cystatin SA has been identified in human submandibular-sublingual saliva by means of basic gel electrophoresis and immunoblotting with anti-cystatin S. Two proteins, SA1 and SA2, are given by two alleles of CST2, viz., CST2*1 and CST*2. Inheritance is controlled by two codominant alleles at an autosomal locus. This hypothesis is supported by studies of 16 families 32 children. Gene frequencies for CST2*1 and CST2*2 are 0.935 and 0.065, respectively (n = 341). Eighteen amino acids determined among 20 N-terminal residues of cystatin SA2 are identical with the sequence encoded by CST2. Three forms of cystatin S (mono-phosphorylated cystatin S, di-phosphorylated cystatin S, and non-phosphorylated cystatin S) are present in the 341 saliva samples tested.

Genetic polymorphism of alpha-1-antitrypsin in macaque species

Thirty-two phenotypes of alpha-1-antitrypsin (al-AT) controlled by 18 codominant alleles of PImac locus were identified by isoelectric focusing in 1.121 macaques of nine species. In terms of al-AT polymorphism macaque species vary markedly from nearly monomorphic (Macaca mulatta, M. arctoides) to highly polymorphic (M. nemestrina, M. fascicularis). Only 4 of 18 PImac alleles are common for two or more macaque species, the rest of the alleles are species-specific.

The effectiveness of using co‐dominant polymorphic allelic series for (1) checking pedigrees and (2) distinguishing full‐sib pair members

Formulae express the effectiveness of parentage exclusion tests and differences separating full-sib pairs by compounding genotypic information on discrete examples of co-dominant alleles segregating at gene loci on different autosomes. Such polymorphisms occur among structural genes and polymorphic DNA sequences. Two general formulae state the theoretical effectiveness of using co-dominant alleles for (1) testing parentage and (2) distinguishing sibs. The formula for parentage exclusion tates the probability (PE) that a given series of co-dominant alleles of known frequency should detect a falsely recorded father (or mother). The other formula describes how genetic polymorphism can distinguished closely related individuals. It states the probability (PS) that alleles distinguish the members of full-sib pairs, dizygotic twins and tissue chimeras. To derive the two general formulae, particular formulae were calculated for n = 2, 3 and 4 co-dominant alleles. By increasing the numbers of alleles, the formulae were seen to contain recurrent patterns which were then expressed in the two general formulae for n alleles. Some examples demonstrate applications of the two formulae in problems concerning parentage and sibship.

Blood protein polymorphisms in the donkey (Equus asinus)

Transferrin, albumin, 6-phosphogluconate dehydrogenase and vitamin D-binding protein polymorphisms were detected in 242 feral and domesticated Australian donkeys by polyacrylamide gel electrophoresis, starch gel electrophoresis, autoradiography, immunoblotting with specific antisera and activity staining. All four TF and two ALB variants were donkey specific while only one of the PGD variants was donkey specific. The two GC variants were electrophoretically identical to the Equus caballus F and S proteins. Available evidence suggested that the TF, ALB, PGD and GC systems are controlled by co-dominant alleles with frequencies of the most common alleles of each system being 0.831, 0.946, 0.957 and 0.861 respectively. Glucose phosphate isomerase and plasminogen were monomorphic in the Australian population of donkeys.

A Gln-281 to Arg substitution in alpha-L-fucosidase is responsible for a common polymorphism detected by isoelectric focusing.

A common polymorphism of human alpha-L-fucosidase consists of three phenotypes (Fu 1, Fu 2, and Fu 2-1) assigned by isoelectric focusing. The phenotypes are determined by two codominant alleles (Fu1 and Fu2). Isozymes with the Fu 2 phenotype have more basic pI than Fu 1, while Fu 2-1 is a mixture of Fu 2 and Fu 1. Recently, a missense mutation (A860-->G) in the alpha-L-fucosidase gene was described that did not affect alpha-L-fucosidase activity. The mutation causes the substitution of Arg (pKaGuan = 12.5) for Gln-281, which has no ionizable side chain. Isoelectric focusing profiles of extracts of COS-1 cells transfected with wild-type or mutant alpha-L-fucosidase cDNAs had phenotypes of Fu 1 and Fu 2, respectively. Next, 20 human lymphoid cell lines were examined for the occurrence of the A860-->G mutation and expression of the Fu 1, Fu 2, and Fu 2-1 phenotypes. Eight lines with Fu 2 were homozygous for the A860-->G mutation; six lines with Fu 1 were homozygous for the normal nucleotide (A860); and six lines with Fu 2-1 were heterozygous. Thus, the A860-->G mutation is the molecular basis for the protein phenotypes and the Fu1 and Fu2 alleles. The normal nucleotide (A860) is responsible for Fu1 and the A860-->G mutation for Fu2.

C3b receptor (CR1) genomic polymorphism in rheumatoid arthritis. Low receptor levels on erythrocytes are an acquired phenomenon.

The number of complement receptor 1 (CR1, CD35) molecules on erythrocytes is genetically determined by two codominant alleles. The numerical expression of CR1 on erythrocytes correlates with a HindIII-RFLP or CR1 gene using CR1-1, a complementary DNA probe. We have found low CR1 on erythrocytes in patients with rheumatoid arthritis (RA) in an Indian population. Low levels in RA patients may be acquired or genetically determined. Fifty-two patients with RA, 48 nonrelated healthy subjects and 19 consanguineous relatives of patients were genotyped. CR1 numbers on erythrocytes were quantitated by the enzyme-linked immunosorbent assay using monoclonal anti-CR1 antibody. Normal subjects and patients were followed up for a period of 6 months to evaluate the stability of their CR1 expression. The gene frequency for allele H and L (7.4- and 6.9-kb HindIII restriction fragment, respectively), which correlated with high and low expression of CR1 on erythrocytes was 0.77 and 0.23 in the normal controls. Gene frequency in RA patients was 0.78 and 0.22 for H and L allele, which did not differ significantly from either controls or relatives (0.80 and 0.20 for H and L allele, respectively). However, RA patients expressed fewer CR1 on erythrocytes within each genotype than their relatives and controls. CR1 on erythrocytes were found to be stable in consecutive samples in controls. In RA patients, the number varied between low and high during the course of the disease. The variation in number was significantly correlated (p < 0.05, r = -0.85 to -0.98) with disease activity as monitored by erythrocyte sedimentation rate. Our results suggest that low levels of CR1 on erythrocytes in patients with RA are not inherited, rather they are acquired during the course of the disease.

Gamete Selection for Simultaneous Improvement of Multiple Traits in Common Bean

A successful crop improvement program depends upon the ability of breeders and geneticists to effectively and efficiently create, identify, and select recombinant genotypes with a maximum number of desirable traits in the shortest time possible. Therefore, alternative methods of gene recombination and selection need to be studied. My objective is to describe a method of gamete selection for simultaneous improvement of multiple traits in common bean (Phaseolus vulgaris L.). Gametes election is based on the premise that (i) multiple‐parent crosses are required for simultaneous improvement of multiple traits; (ii) the male parents of the final crosses are heterozygous and hence heterogametic;( iii) each zygotic seed is a product of a separate, independent fertilization event; (iv) further chromosomal and genic recombination is limited to genetic material contained within each initial zygote; and (v) early generation (i.e., F1, F2, F3, and F4) testing and selection are an essential part of the methodology. Thus, eventually, plant‐to‐plant pairwise pollination is done between the elite female and beterogametic male parents (selected a priori for desirable dominant and codominant alleles), followed by harvesting and sowing resultant hybrid seeds from each hybridization event in separate plots to obtain F1‐derived families. These are subsequently evaluated in separate, replicated complementary nurseries for seed yield and other agronomic traits, including reactions to diseases and insects, low soil fertility, and/or drought. This permits identifying promising populations and families within populations possessing genes for multiple desirable traits in early generations for further evaluation, selection, and development of improved cultivars.

Occurrence of prochymosin variants in the abomasum of bovine foetuses and calves.

Prochymosin variants were analysed in single abomasa from 67 foetuses (3-9 months of gestation) and 33 calves (about 6 weeks old) of Black-and-White cattle collected in a slaughter house. The method of agarose gel electrophoresis followed by detection of proteolytic activity was used. Three distinct prochymosins A, B and C that occurred singly or in pairs (with equal proteolytic activities of both components) were found. Chymosin A, B and C obtained after conversion of corresponding prochymosins, demonstrated similar electrophoretical mobilities like the three chymosin fractions contained in commercial rennin (Sigma, USA). Our chymosin B showed identical mobility as the amidated form of recombined chymosin B contained in Chymogen (Chr. Hansen's Lab., Denmark A/S). Prochymosin A, B and C in the examined animals were precursors of corresponding chymosins and were controlled by three separate codominant alleles. The following prochymosin phenotypes were found: AA (30), AB (32), AC (4), BB (29), BC (4) and CC (1). Chi-square analysis demonstrated significant differences between the observed and expected numbers of phenotypes. The gene frequencies of prochymosin A, B and C were 0.48, 0.47 and 0.05, respectively.

Genetic studies of water buffalo blood markers. II. Carbonic anhydrase, esterase D, malate dehydrogenase, and malic enzyme.

To determine the genetic diversity of water buffaloes Bubalus bubalis, which underpins their genetic well-being over time, as well as efforts to improve their meat and milk yields, it is necessary first to estimate the genetic distances within and between populations of various geographical locations. Electrophoretic techniques provide the means to do this by estimating gene frequencies for polymorphic genetic markers. Cellulose acetate electrophoresis, the technique employed in this study, allows rapid and efficient screening for the presence of polymorphism in an enzyme (Tan et al., 1989). Makaveev (1978) has shown, using starch gel electrophoresis and family studies, that water buffalo malate dehydrogenase is encoded by a locus with two codominant alleles, M D H A and M D H B. Iorio and Annunziata (1986), using cellulose acetate electrophoresis, reported that the three water buffalo carbonic anhydrase phenotypes they observed were encoded by codominant alleles, CA F and CA s, but no family study was done to confirm this interpretation. Esterase D of water buffaloes was reported by Tan et al. (1980) to be polymorphic and encoded by two codominant alleles, E S D V and E S D s, on starch gel electrophoresis but no family data were available. In this paper family studies on animals with known pedigrees were conducted to ascertain whether the polymorphic genetic markers that we

Heteroduplex molecules formed between allelic sequences cause nonparental RAPD bands.

Primers (10-mers) of random sequence were used to amplify RAPD bands from genomic DNA of an F1 strain of flax rust (Melampsora lini) and its two parent strains. One primer out of 160 tested was unusual in that it amplified a product from F1 DNA that was not amplified from either parental DNAs. The same primer also generated two RAPD bands that segregated as codominant alleles amongst F2 progeny. The nonparental band was only generated from DNAs of F2 individuals that were heterozygous for these two allelic sequences. Sequence analysis of the two RAPD alleles demonstrated greater than 99% sequence identity, although the larger allele possessed an additional 38bp relative to the smaller. Mixing of the two allelic sequences followed by denaturation and annealing in the absence of polymerase activity resulted in the formation of the nonparental band. Thus the nonparental band present in some RAPD reactions consisted of a heteroduplex molecule formed between two allelic sequences of different size. These data demonstrate that heteroduplex molecules formed between allelic RAPD products are a potential source of artifactual polymorphism that can arise during RAPD analysis.

Allelic polymorphism in the coding region of human TCR C alpha gene and characterization of structural variability in the alpha chain constant domain.

An allelic variant of the human TCR C alpha gene, designated C alpha AL, which encodes a structurally different protein product has been characterized. C alpha AL was independently sequenced using polymerase chain reaction (PCR)-amplified TCR C alpha cDNA from various T cell clones derived from a same individual. It differed from the most usual C alpha sequence by two non-synonymous base changes at codons 4 (AAC-->AAG) and 84 (GAA-->GCA) of the C alpha coding region. These changes imply amino acid substitutions Asn-->Lys and Glu-->Ala respectively. An oligotyping method, based on hybridization of allele-specific oligonucleotides to PCR-amplified C alpha DNA, is also described. It was used for differential typing of the two C alpha forms in family and population studies. In each of three T cell clones analyzed from the same donor having two rearranged TCR alpha chain transcripts, C alpha AL was found in only one of the transcripts. In addition, C alpha AL segregated as a co-dominant mendelian allele within the family of this donor. Population analysis was carried out in 73 spanish individuals. Twelve donors (16.4%) were heterozygous, implying that C alpha AL was present in this population sample with an allelic frequency of 0.08. The observed frequencies of C alpha genotypes were those expected for the two alleles being in Hardy-Weinberg equilibrium. This demonstration of structural polymorphism in the constant region of TCR alpha chains provides a useful genetic marker for TCR and disease association studies due to its precise mapping within the C alpha coding region, and its significant frequency in the analyzed population.(ABSTRACT TRUNCATED AT 250 WORDS)

Joint Segregation of Allozymes in Catfish Genetic Crosses: Designation ofIctalurus punctatusLinkage Group I

Polymorphic isozymes visualized by starch gel electrophoresis and histochemical staining were examined in parents and 1,000 progeny of 24 single-pair matings of channel catfish Ictalurus punctatus and three interspecific crosses of channel catfish × blue catfish I. furcatus. Polymorphic loci that could be scored from fin tissue included aconitate hydratase (mAH*), glucose-6-phosphate isomerase (GPI-B*), glutathione reductase (GR*), phosphoglucomutase (PGM*), and UDPglucose-hexose-1-phosphate uridylyltransferase (UGHUT-2*). Inheritance of observed electrophoretic variation was consistent with Mendelian segregation of codominant alleles in progeny selected randomly from the individual crosses. Although mAH*, GPI-B*, PGM*, and UGHUT-2* appeared to assort independently within the limits of the data, strong evidence for linkage of GR* and PGM* was obtained (19.7% recombination, P ≤ 0.001 for data combined from two informative pedigrees); this linkage was designated Ictalurus punctatus linkage group I. This study represented a first step in assembly of a catfish gene map large enough to provide genetic markers for each catfish chromosome to enable detection of specific loci associated with traits of economic importance by genetic linkage analyses. For the polymorphic loci studied here, no consistent association of genotype with average body weight was observed.

Genetic markers for the Booroola fecundity (Fec) gene in sheep

Animals from the Booroola line of Australian Merino sheep are characterized by a high ovulation rate that can be attributed to the presence of a codominant allele (FecB). The specific function of the gene has not been identified. Effective use of the trait within the sheep breeding industry requires one or more genetic markers that can distinguish between alternative alleles at the locus Fec. With a combination of DNA minisatellite markers and polymorphic protein markers, a cluster of seven minisatellite fragments has been identified as being linked to the Fec gene and to the ovine A blood group locus. The minisatellite fragments have been derived from multilocus probes and hence cannot be used to define the chromosomal location of the Fec gene or to serve as diagnostic markers for Fec. The derivation of cloned single locus markers from the minisatellite fragments will enable finer scale mapping of the Fec and the A blood group locus in sheep.

RFLP approach to breeding for quantitative traits in plants—a critique

A number of recent papers suggest that use of RFLPs as markers offers a clear advantage in breeding for improvement in quantitative traits (QTs). The concepts underlying establishment of linkage between RFLP markers and QT loci stem from three papers on tomato published during 1987–1991. Essentially, continuously varying QT phenotypes are assigned to RFLP genotype classes, which can be considered to be determined by a single, diallelic gene with codominant alleles. Linkage is inferred through statistical analysis. Similarly, interaction between markers and QT is also tested by an analysis of variance. Here, the statistical methods employed in these three papers to detect linkage are critically evaluated, especially because subsequent investigations take the concepts developed in these papers as proven. In this paper, we examine the three fundamental papersde novo. We scrutinize the methods employed and the inferences drawn to bring to light what we believe are conceptual drawbacks.

Intraspecific variation in serum proteins of brown hare ( Lepus europaeus Pallas, 1778)

1. 1. Serum proteins of brown hare ( Lepus europaeus Pallas, 1778) were studied by the use of 1D PAGE, 2D agarose-PAGE, immunoblotting, inhibitions of trypsin and chymotrypsin, and specific staining for esterase. 2. 2. Some serum proteins were identified, and easily interpretable polymorphisms were found in transferrin, α 1 B glycoprotein, protease inhibitors ATC2, ATC3 and AT1, esterase ES1 and in an unidentified postalbumin PO. 3. 3. On the basis of family studies the evidence was obtained that the variants observed in these polymorphic proteins are under genetic control by codominant alleles of autosomal loci.

Polymorphism of alpha-1 antitrypsin in dogs

1. 1. A genetically determined polymorphism of alpha-1 antitrypsin is demonstrated in dog serum by isoelectric focusing in a pH range of 3.5–5.0, followed by direct immunoblotting using a specific antiserum. 2. 2. Alpha 1 antitrypsin focuses as two major bands at isoelectric points of 4.60 and 4.64 or 4.67 and 4.7 in presumed homozygous animals. Heterozygotes show both sets of bands. 3. 3. The results of seven crosses with 33 offspring are best explained by two codominant alleles, Pi M and Pi S at a single locus designated as Pi for proteinase inhibitor. 4. 4. The concentration of alpha-1 antitrypsin in serum of healthy dogs was 2.65 ± 0.42 mg/ml and 2.19 ± 0.38 mg/ml in females andv males respectively. 5. 5. The higher concentration in female dogs suggests that estrogens may influence the serum level of alpha-1 antitrypsin.

Characterization of apo(a) polymorphism by a modified immunoblotting technique in an italian population sample

Apo(a), the specific lipoprotein(a) (Lp(a)) apolipoprotein, is characterized by different isoforms (from 6 to 11 on SDS-PAGE) encoded by a system of autosomal codominant alleles. Electrophoresis on agarose gel displays a better resolving power than SDS-PAGE (a larger number of apo(a) isoforms is detected). The aim of this work was to set up a simple technique that uses a capillary blotting apparatus and a polyvinylidene difluoride membrane for protein transfer. We tested an Italian population sample of 202 healthy subjects (123 men and 79 women) and we detected 22 apo(a) isoforms varying from 280 to 775 kDa. In our sample, 135 subjects (66.5%) had a single-band phenotype, 64 (31.7%) had a double-band phenotype and 3 subjects (1.5%) had no detectable bands (‘null’ phenotype). This simple and reproducible technique could be applied in the genetic screening of apo(a) polymorphisms and for clinical investigations of the risk of developing cardiovascular diseases.

Expression of α-glycerophosphate dehydrogenase during the development and aging of malaria vector Anopheles stephensi (Diptera: Culicidae)

α-Glycerophosphate dehydrogenase (GPDH) expression during the complete development and aging of Anopheles stephensi has been studied by electrophoretic and spectrophotometric techniques. Single gene locus seems to govern the developmental expression of three isozymes numbered from GPDH-1 to GPDH-3 in order of decreasing mobility. GPDH-3 was present in all the stages of development. GPDH-1 disappeared during senescence. GPDH-2, the band of intermediate mobility, was adult specific. GPDH-1 has been indicated to be more suitable for energy metabolism and GPDH-3 for lipid biosynthesis. Three codominant alleles control the four electrophoretic variants revealed in the laboratory strain. Quantitatively, the activity of GPDH continuously increased during development and showed its peak on day-4 adults of both sexes. However, the activity decreased during senescence. Tissue and sex specific differences in isozymes pattern have also been analysed. Changes in isozymes and specific activity have been correlated with the various physiological and morphological events occurring during development.

Biochemical and genetic studies on alkaline phosphatase ofCeratitis capitata

Two forms of alkaline phosphatase exist in the integument of the "white pupae" (wp) and dark pupae (dp) mutant strains of Ceratitis capitata, during transition from larvae to pupae. They were separated by DEAE-cellulose chromatography. Both isoenzymes have a molecular weight of approximately 180,000 and two pH optima, at 9.4 and at 11.0. The isoenzymes of the "dark pupae" mutant catalyze the hydrolysis of phosphotyrosine and beta-glycerophosphate but not phosphoserine, phosphothreonine, ATP, and AMP. In contrast, the isoenzymes of the white pupae mutant hydrolyze all the substrates tested. The ALPase 1 of the dark pupae mutant was inhibited by L-tyrosine, but L-phenylalanine had no effect on either isoenzyme. The effects of divalent cations, EDTA, temperature, urea, and 2-mercaptoethanol were also investigated. Electrophoretic analysis did not reveal any variants of the larval and pupal isoenzymes, but ALPase A, an adult stage-specific isoenzyme, was found to be polymorphic. The electrophoretic variants were shown to be controlled by three codominant alleles located on the third chromosome of Ceratitis capitata. Since we found no hybrid enzyme, we conclude that ALPase A is monomeric.

Genetic polymorphism of histone H1.z in duck erythrocytes

Three different phenotypes of erythrocyte histone H1.z were detected in several lines of duck by using two-dimensional PAGE. Electrophoresis and inheritance data have shown that two co-dominant alleles, z1 and z2, encode two proteins which differ slightly in their apparent molecular masses. Allele z1 was very abundant and was found at a frequency at least 0.94, while allele z2 was very rare and was present at a frequency of less than 0.06. Limited chemical and enzymic cleavages appeared to indicate that the allelic forms of histone H1.z differed in the C-terminal regions of their molecules.