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.     

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, PH1 , and Xk has thus been established. The possibility that the linkage between PH1 and Xk is homologous to the linkage between the loci for PHI and a serum postalbumin (PO-2) in pigs was discussed.     

The gene for coagulation factor XIII a subunit (F13A) is distal to HLA on chromosome 6

Summary The locus coding for the A subunit of coagulation factor XIII (F13A) is strongly linked with the major histocompatibility complex on chromosome 6. The maximum lod score was obtained at recombination fractions of 0.12 in males and 0.40 in females. The data suggest that the F13A locus is distal to HLA, probably within the 6p22 region.     

Genetic variation,inheritance, and quaternary structure of malic enzyme in brook trout (Salvelinus fontinalis)

Electrophoretic variation is described for malic enzyme (ME) for the first time in brook trout (Salvelinus fontinalis). Since the quaternary structure of ME was not clear from examination of banding patterns in brook trout alone, ME phenotypes in rainbow trout (Salmo gairdneri) × brook trout hybrids as well as in esocid species demonstrated that ME is tetrameric. A model of two duplicated loci is proposed to account for the observed variation. One locus (ME-2) is fixed and one locus (ME-1) is variable with three electrophoretically distinct alleles; the protein products of ME-1 are reduced in activity relative to the protein products of ME-2. Joint segregation was examined between ME-1 and ten other biochemical loci in brook trout, and between ME-1, ME-2, and nine other biochemical loci in a splake—lake trout (Salvelinus namaycush) × brook trout hybrid—backcross. All pairwise examinations showed random assortment except ME-2 with an isocitrate dehydrogenase locus (IDH-3), which showed complete linkage in the splake backcross. This may be due to a chromosomal aberration.Authorized for publication as Paper No. 5599 in the Journal Series of The Pennsylvania Agricultural Experiment Station, University Park, Pennsylvania, in cooperation with the Benner Spring Fish Research Station, The Pennsylvania Fish Commission, Bellefonte, Pennsylvania. M.S. was supported by an NSF Graduate Fellowship.     

Tight linkage of the gene for spinocerebellar ataxia to D6S89 on the short arm of chromosome 6 in a kindred for which close linkage to both HLA and F13A1 is excluded.

A locus for an autosomal dominant form of spinocerebellar ataxia (SCA1) has been assigned to the short arm of chromosome 6 on the basis of linkage to the major histocompatibility system (HLA). In this study of a five-generation American black family, close linkage between the disease locus and both HLA and the coagulation factor XIIIA (F13A1) locus was excluded, and lod scores for all locations of the disease locus between HLA and F13A1 were less than -1.4. These results suggest that the locus causing spinocerebellar ataxia in this family is not in this region. However, the disease locus was found to be closely linked to a microsatellite polymorphism, D6S89, which is between HLA and F13A1. The maximum lod score for SCA1 and D6S89 is 4.90 at a recombination fraction of 0, both in males and in females. These data show that exclusion of close linkage to the HLA complex and F13A1 in a kindred with spinocerebellar ataxia does not rule out the possibility that the disease locus in that family is on 6p. Accordingly, all families segregating a dominantly inherited ataxia should be evaluated for linkage to D6S89, to determine whether the locus causing the disease is SCA1.     

Genetics of the quantitative Lp(a) lipoprotein trait

The Lp(a) lipoprotein is a complex particle composed of a low density lipoprotein (LDL)-like lipoprotein and the disulfide bonded Lp(a) glycoprotein. The complex represents a quantitative genetic trait. SDS gel electrophoresis under reducing conditions of sera followed by immunoblotting with affinity-purified polyclonal anti-Lp(a) demonstrated inter- and intra-individual size heterogeneity of the glycoprotein with apparent Mr in the range 400-700kDa. According to their relative mobilities compared to apo B-100 the Lp(a) patterns were categorized into phenotypes F, B, S1, S2, S3 und S4 and into the respective double-band phenotypes. This size heterogeneity seems to be controlled by multiple alleles designated LpF, LpB, LpS1, LpS2, LpS3, LpS4 and a null allele (LpO) at a single locus. Phenotype frequencies observed in 441 unrelated subjects were in good agreement with those expected from the genetic hypothesis. Comparison of Lp(a) lipoprotein concentrations in the different phenotypes revealed a highly significant association of phenotypes B, S1 and S2 with high, and phenotypes S3 und S4 with intermediate Lp(a) concentrations. A third mode is represented by the null phenotype were no Lp(a) band is detected upon immunoblotting and Lp(a) lipoprotein is low or absent. We conclude that the same gene locus is involved in determining Lp(a) glycoprotein phenotype and Lp(a) lipoprotein concentrations in plasma. This major gene seems to be the Lp(a) glycoprotein structural gene locus.     

Utility of a C-Jun Microsatellite Marker in Determining Gene Dosage for fatty (fa)

The Zucker fatty (fa) mutation provides a genetic model for obesity and non-insulin dependent diabetes mellitus. The molecular pathogenesis of the metabolic phenotype of these animals is not known. Detailed molecular maps of the region surrounding the fa locus on rat chromosome 5 can be used for positional cloning experiments as well as to permit genotyping of animals from appropriate crosses before the confounding metabolic effects of obesity have occurred. We describe the development of a polymerase chain reaction (PCR) assay for a polymorphic simple sequence repeat (SSR) in the promoter region of the protooncogene c-Jun. This assay was used to position cJun 4.5cM proximal to the fa locus in 111 F2 progeny of a 13MBN fa/+ F1 intercross. Concurrent use of the cJun SSR with a previously described assay for a microsatellite in the glucose transporter, Glutl, permits rapid and accurate assessment of genotypes at the fa locus in animals of any age using minimal amounts of DNA. A strategy is described which minimizes the error rate in assigning genotype at the fatty locus for backcross and intercross progeny.     

The genetics of coat colors in the mongolian gerbil (Meriones unguiculatus)

Genetic studies demonstrated three loci controlling coat colors in the Mongolian gerbil. F1 hybrids of white gerbils with red eyes and agouti gerbils with wild coat color had the agouti coat color. The segregating ratio of agouti and white in the F2 generation was 3:1. In the backcross (BC) generation (white x F1), the ratio of the agouti and white coat colors was 1:1. Next, inheritance of the agouti coat color was investigated. Matings between agouti and non-agouti (black) gerbils produced only agouti gerbils. In the F2 generation, the ratio of agouti to non-agouti (black) was 3:1. There was no distortion in the sex ratios within each coat color in the F1, F2 and BC generations. This indicated that the white coat color of gerbils is governed by an autosomal recessive gene which should be named the c allele of the c (albino) locus controlling pigmentation, and the agouti coat color is controlled by an autosomal dominant gene which might be named the A allele of the A (agouti) locus controlling pigmentation patterns in the hair. The occurrence of the black gerbil demonstrated clearly the existence of the b (brown) locus, and it clearly indicated that the coat colors of gerbils can basically be explained by a, b, and c loci as in mice and rats.     

Linkage analysis between the partial restoration (pr) and the restorer-of-fertility (Rf) loci in pepper cytoplasmic male sterility

Cytoplasmic male sterility (CMS) in chili pepper is restored by one major dominant nuclear gene, restorer-of-fertility (Rf), together with some modifier genes and is also affected by temperature. As a result, male fertility was identified as having several phenotypes. That identified and used in the present study allowed partial restoration of fertility, producing plants that simultaneously produce normal and aborted pollen grains, with most grains stuck to the anther wall, even after dehiscence, resulting in low seed set per fruit. The trait was visible only in the presence of Paterson's sterile cytoplasm and was controlled by a recessive nuclear gene, partial restoration (pr). A CAPS marker, PR-CAPS, closely linked to the trait, has been developed by Lee et al. (2008). In this study, linkage analysis was performed in 205 F(2) individuals derived from the 'Buja' Korean commercial F(1) chili pepper variety using the PR-CAPS marker and the three Rf-linked markers (OPP13-CAPS, AFRF8-CAPS, and CRF-SCAR) previously reported. Consequently, we found that these four markers were tightly linked. This result means that the pr gene might be tightly linked to the Rf locus or the third allele of Rf locus. The sequence diversity of the pr- and Rf-linked markers was also analyzed. The internal sequences of OPP13-CAPS (1,180 bp) and PR-CAPS (640 bp) markers in 91 Korean inbred lines were clearly divided into three haplotypes. According to the sequencing results, a new PR-CAPS (MseI or SphI digestion) marker was designed to distinguish the three haplotypes. This marker will be useful for marker-assisted selection to develop new maintainers and restorers in commercial hybrid pepper breeding using CMS.     

A structural locus for coagulation factor XIIIA (F13A) is located distal to the HLA region on chromosome 6p in man

Linkage between the locus for coagulation factor XIIIA (F13A) and HLA-region genes has been revealed during a linkage study between F13A and approximately 40 other polymorphic marker genes. In males, the maximum lod score between F13A and HLA-region genes (HLA-A, -C, -B, -DR; C4A, -B; Bf; and/or C2) is 7.60 at theta 1 = .18. To GLO, the maximum lod score is 2.37 at theta 1 = .19; to PGM3, .22 at theta 1 = .35. Female data indicate a clear sex difference in recombination frequency between F13A and HLA. The present findings, in combination with earlier knowledge of PGM3/GLO/HLA localization and gene distances, show that F13A is distal to HLA on the short arm of chromosome 6 in man. It is thus likely that by including FXIIIA typing in linkage studies, the whole male 6p is within mapping distance of highly polymorphic, classical marker genes. Earlier findings that the Hageman factor gene (F12) is located in the same chromosomal region may indicate the presence of a coagulation factor gene cluster in this region.     

Genetic variation in isozymes of wild boar (Sus scrofa ferus Linné)

Eleven isozyme systems were investigated in wild boar (Sus scrofa ferus L.) by means of horizontal starch gel-electrophoresis using liver and kidney extracts. Samples of 103 specimen that originated from three adjunct localities from Rhineland-Palatinate (Fed. Rep. Germany) were analysed. AAT, ACO, GDH, GPDH, LDH, ME, MPI, MR, PGDH, and PGI were invariant. Genetic polymorphism is described for PGM. The genetic polymorphism at Pgm2 is explained by a biallelic model. Observed genotypic structure did not differ significantly from Hardy-Wein-berg-proportions at this gene locus. The degree of heterozygosity is 58,3 % and Wright's Fixation Index F =–0.166 at Pgm2. The allelic structure at this gene locus differed to a great extent from that found in domestic swine, i. e. in domestic swine the faster migrating Pgm2 allozyme was only found in relative low frequencies compared to wild boar. The genetic polymorphisms were moderate in the wild boar population compared to electrophoretic data of other animal species.     

Development and fine mapping of three co-dominant SCAR markers linked to the <Emphasis Type="Italic">M/m</Emphasis> gene in the cucumber plant (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.)

Owing to its diverse sex types, the cucumber plant has been studied widely as a model for sex determination. In addition to environmental factors and plant hormones, three major genes—F/f, M/m, and A/a—regulate the sex types in the cucumber plant. By combining the bulked segregant analysis (BSA) and the sequence-related amplified polymorphism (SRAP) technology, we identified eight markers linking to the M/m locus. Among them, the two closely linked SRAP markers flanking the M/m locus were the co-dominant marker ME1EM26 and the dominant marker ME1EM23. Further, the co-dominant marker ME8SA7 co-segregated with the M/m locus. With the chromosome walking method using the cucumber genomic bacterial artificial chromosome (BAC) library, we successfully developed a co-dominant SCAR marker S_ME1EM23 from the ME1EM23 sequence. Along with the other two co-dominant SCAR markers S_ME1EM26 and S_ME8SA7 (developed from ME1EM26 and ME8SA7, respectively) in a larger segregating population (900 individuals), the M/m locus was mapped between S_ME1EM26 (5.4 cM) and S_ME1EM23 (0.7 cM), and S_ME8SA7 co-segregated with it. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Z. Li and J. Pan contribute equally to this article.     

A population study of leukocyte enzymes (GOT2, ME2 and PGM3) in Galicia (NW Spain)

Genetic variants of leukocyte mitochondrial glutamate oxaloacetate transaminase, mitochondrial malic enzyme and phosphoglucomutase locus III were studied in the Galician population. There was no significant heterogeneity between 8 Galician subpopulations. The gene frequencies in the total population were: GOT(2)2 = 0.025; ME(2)2 = 0.408; PGM(2)3 = 0.333. No rare variants were found.     

Equine gene mapping: Close linkage between the loci for soluble malic enzyme and Xk (Pa)

Resolution of equine soluble malic enzyme phenotypes is greatly improved by isoelectric focusing as compared with starch gel electrophoresis. Phenotype differences can be recognized in plasma as well as haemolysates. The locus for soluble malic enzyme (ME1) is closely linked to the locus for Xk.     

Analysis for linkage between F13A and three chromosome 6 marker loci: evidence for 6pter: F13A:HLA:GL01:cen gene order

Summary The results of the present study provide independent support for F13A:HLA linkage and refine the F13A: HLA and F13A: GLO1 linkage relationships. Analysis of the corresponding recombination fractions for the total paternal F13A:HLA and F13A:GLO1 peak lod scores() indicates a locus order of 6pter: F13A:HLA:GLO1:cen. Lod scores between F13A and PLG, a locus recently assigned to chromosome 6, exclude close linkage between these loci.     

Genetics and polymorphism of a duplicated malate dehydrogenase (MDH) locus in the grasshopperOxya japonica japonica (Orthoptera:Acrididae:Oxyinae)

A biochemical genetic study of the enzyme malate dehydrogenase (MDH) was conducted in the grasshopperOxya j. japonica. Analysis of MDH electrophoretic variation in this species of grasshopper shows that one of the two autosomal loci for MDH in grasshoppers, the Mdh-2 locus, controlling the anodal set of MDH isozymes, is duplicated. Results of breeding studies confirm this and the observed polymorphism at theMdh-2 locus in the two populations ofOxya j. japonica studied can be attributed to three forms of linked alleles at the duplicated locus in equilibrium in both populations. In this respect, all individuals of this species possess heterozygous allelic combinations at the duplicatedMdh-2 locus, which may account for the spread of the duplicated locus in the populations of this species of grasshopper.This research was supported by a grant (Vote F) from the University of Malaya, Kuala Lumpur.     

Genetic mapping of X-linked albinism-deafness syndrome (ADFN) to Xq26.3-q27.1

X-linked albinism-deafness syndrome (ADFN) was described in one Israeli Jewish family and is characterized by congenital nerve deafness and piebaldness. The ADFN mutation probably affects the migration of neural crest-derived precursors of the melanocytes. As a first step toward identifying the ADFN gene, a linkage study was performed to localize the disease locus on the X chromosome. The family was found to be informative for 11 of 107 RFLPs along the X, and two-point analysis showed four of them--factor 9 (F9), DXS91, DXS37, and DNF1--to have definite or suggestive linkage with ADFN. Multipoint linkage analysis indicated two possible orders within this cluster of loci, neither of which was preferable. In both orders F9 was the most distal, and the best estimate for the location of ADFN was between F9 and the next proximal marker (8.6 cM from F9 [Z = 8.1] or 8.3 cM from F9 [Z = 7.9]). These results suggest that the ADFN is at Xq26.3-q27.1. Disagreement between our data and previous localization of DXS91 at Xq11-q13 was resolved by hybridization of the probe pXG-17, which detects the DXS91 locus, to a panel of somatic cell hybrids containing different portions of the X chromosome. This experiment showed that this locus is definitely at Xq24-q26. Together with the linkage data, our results place DXS91 at Xq26 and underscore the importance of using more than one mapping method for the localization of molecular probes.     

Localization of the coagulation factor XIII A subunit gene (F13A) to chromosome bands 6p24----p25

Electrophoretic studies of the genetic variation of the A subunit of coagulation factor XIII (F13A) have shown that the A subunits expressed in placenta and in the circulation are the products of the same gene locus. In situ hybridization studies with a cDNA fragment encoding the amino terminal region of the A subunit have localized the gene to bands p24----p25 on chromosome 6. This confirms previous studies that showed linkage between F13A and the major histocompatibility complex.     

Formation in Rhizobium and Agrobacterium spp. of a 235-kilodalton protein intermediate in beta-D(1-2) glucan synthesis.

beta-D(1-2) Glucan was synthesized by Agrobacterium and Rhizobium spp. in vitro with enzymes from the internal membranes upon the addition of UDF glucose and Mg2+ or Mn2+. An intermediate containing protein and beta-D(1-2) glucan was formed during the reaction. It could be precipitated with trichloroacetic acid or separated by polyacrylamide gel electrophoresis under denaturing conditions. After detection with Coomassie blue or a radioactive substrate, the intermediate appeared as a 235-kilodalton protein. The radioactivity could be chased with a nonradioactive substrate. All strains that formed beta-D(1-2) glucan in vitro formed the 235-kilodalton protein, whereas avirulent, beta-D(1-2) glucan-negative mutants did not synthesize it. Transposon insertions in the chvB locus of strains ME2 and ME116 did not alter the virulence of the strains. These strains were able to form beta-D(1-2) glucan in vitro and synthesize the 235-kilodalton protein.     

Polymorphism and inheritance of serum esterases and beta-globulins in the paradise fish (Macropodus opercularis; Anabantidae)

Electrophoretic variants of serum esterases and beta-globulins in two subspecies of paradise fish (Macropodus opercularis) were studied. Four esterase loci (Est-1, Est-2, Est-3 and Est-4), a single transferrin (Tf) and another major beta-globulin locus (Bg) were identified by segregational analysis. Est-3 seems to be a monomorphic locus. Three alleles of Est-1, two of Est-2, two of Est-4, four of Tf and two alleles of Bg were found in the laboratory population. None of these loci were closely linked. Electrophoretic patterns of F1 hybrids confirmed the monomeric structures of each of the studied proteins. Allelic segregation at the Tf and Bg loci was normal in F2 and backcross populations. In crosses of the two Macropodus subspecies there were deviations from Mendelian ratios because of missing recombinant esterase phenotypes. Each of these would have been homozygous Est-2f/f. We suppose that Est-2f/f causes lethality in the early phase of development, except in the Est-1c/c, Est-2f/f combination characteristic of the parental subspecies M.o. concolor.