scholarly journals Population genetics of the highly polymorphicRPP8gene family

2019 ◽  
Author(s):  
Alice MacQueen ◽  
Dacheng Tian ◽  
Wenhan Chang ◽  
Eric Holub ◽  
Martin Kreitman ◽  
...  
Keyword(s):  
Balancing Selection ◽  
Direct Repeat ◽  
Single Copy ◽  
Histocompatibility Complex ◽  
Locus System ◽  
High Level ◽  
Eukaryotic Genomes ◽  
Shared Polymorphism ◽  
Selfing Species ◽  
Shared Variation

AbstractPlant NLR resistance genes provide some of the most extreme examples of polymorphism in eukaryotic genomes, rivalling even the vertebrate major histocompatibility complex. Surprisingly, this is also true inArabidopsis thaliana, a predominantly selfing species with low heterozygosity. Here, we investigate how gene duplication and intergenic exchange contribute to this extraordinary variation.RPP8is a three-locus system that is configured chromosomally as either a direct-repeat tandem duplication or as a single copy locus, plus a locus 2 Mb distant. We sequenced 48RPP8alleles from 37 accessions ofA. thalianaand 12RPP8alleles fromA. lyratato investigate the patterns of interlocus shared variation. The tandem duplicates display fixed differences and share less variation with each other than either shares with the distant paralog. A high level of shared polymorphism among alleles at one of the tandem duplicates, the single-copy locus and the distal locus, must involve both classical crossing over and intergenic gene conversion. Despite these polymorphism-enhancing mechanisms, the observed nucleotide diversity could not be replicated under neutral forward-in-time simulations. Only by adding balancing selection to the simulations do they approach level of polymorphism observed atRPP8. In this NLR gene triad, genetic architecture, gene function and selection all combine to generate diversity.

scholarly journals Population Genetics of the Highly Polymorphic RPP8 Gene Family

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 691 ◽  
Author(s):  
Alice MacQueen ◽  
Dacheng Tian ◽  
Wenhan Chang ◽  
Eric Holub ◽  
Martin Kreitman ◽  
...  
Keyword(s):  
Balancing Selection ◽  
Direct Repeat ◽  
Single Copy ◽  
Arabidopsis Lyrata ◽  
Histocompatibility Complex ◽  
Locus System ◽  
High Level ◽  
Eukaryotic Genomes ◽  
Shared Polymorphism ◽  
Selfing Species

Plant nucleotide-binding domain and leucine-rich repeat containing (NLR) genes provide some of the most extreme examples of polymorphism in eukaryotic genomes, rivalling even the vertebrate major histocompatibility complex. Surprisingly, this is also true in Arabidopsis thaliana, a predominantly selfing species with low heterozygosity. Here, we investigate how gene duplication and intergenic exchange contribute to this extraordinary variation. RPP8 is a three-locus system that is configured chromosomally as either a direct-repeat tandem duplication or as a single copy locus, plus a locus 2 Mb distant. We sequenced 48 RPP8 alleles from 37 accessions of A. thaliana and 12 RPP8 alleles from Arabidopsis lyrata to investigate the patterns of interlocus shared variation. The tandem duplicates display fixed differences and share less variation with each other than either shares with the distant paralog. A high level of shared polymorphism among alleles at one of the tandem duplicates, the single-copy locus and the distal locus, must involve both classical crossing over and intergenic gene conversion. Despite these polymorphism-enhancing mechanisms, the observed nucleotide diversity could not be replicated under neutral forward-in-time simulations. Only by adding balancing selection to the simulations do they approach the level of polymorphism observed at RPP8. In this NLR gene triad, genetic architecture, gene function and selection all combine to generate diversity.

Recombination, Balancing Selection and Phylogenies in MHC and Self-Incompatibility Genes

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1833-1844 ◽  
Author(s):  
Mikkel H Schierup ◽  
Anders M Mikkelsen ◽  
Jotun Hein
Keyword(s):  
Major Histocompatibility Complex ◽  
Phylogenetic Tree ◽  
Balancing Selection ◽  
Nucleotide Sequences ◽  
Recombination Process ◽  
Self Incompatibility ◽  
Selection Coefficient ◽  
Histocompatibility Complex ◽  
A Site ◽  
Possible Cause

AbstractUsing a coalescent model of multiallelic balancing selection with recombination, the genealogical process as a function of recombinational distance from a site under selection is investigated. We find that the shape of the phylogenetic tree is independent of the distance to the site under selection. Only the timescale changes from the value predicted by Takahata's allelic genealogy at the site under selection, converging with increasing recombination to the timescale of the neutral coalescent. However, if nucleotide sequences are simulated over a recombining region containing a site under balancing selection, a phylogenetic tree constructed while ignoring such recombination is strongly affected. This is true even for small rates of recombination. Published studies of multiallelic balancing selection, i.e., the major histocompatibility complex (MHC) of vertebrates, gametophytic and sporophytic self-incompatibility of plants, and incompatibility of fungi, all observe allelic genealogies with unexpected shapes. We conclude that small absolute levels of recombination are compatible with these observed distortions of the shape of the allelic genealogy, suggesting a possible cause of these observations. Furthermore, we illustrate that the variance in the coalescent with recombination process makes it difficult to locate sites under selection and to estimate the selection coefficient from levels of variability.

scholarly journals MICA*019 Allele and Soluble MICA as Biomarkers for Ankylosing Spondylitis in Taiwanese

2021 ◽  
Vol 11 (6) ◽  
pp. 564
Author(s):  
Chin-Man Wang ◽  
Keng-Poo Tan ◽  
Yeong-Jian Jan Wu ◽  
Jing-Chi Lin ◽  
Jian-Wen Zheng ◽  
...  
Keyword(s):  
Immune Responses ◽  
Significant Risk ◽  
Significant Risk Factor ◽  
Healthy Controls ◽  
Hla B27 ◽  
Host Immune Responses ◽  
Histocompatibility Complex ◽  
High Level ◽  
Coding Snp

MICA (major histocompatibility complex class I chain-related gene A) interacts with NKG2D on immune cells to regulate host immune responses. We aimed to determine whether MICA alleles are associated with AS susceptibility in Taiwanese. MICA alleles were determined through haplotype analyses of major MICA coding SNP (cSNP) data from 895 AS patients and 896 normal healthy controls in Taiwan. The distributions of MICA alleles were compared between AS patients and normal healthy controls and among AS patients, stratified by clinical characteristics. ELISA was used to determine soluble MICA (sMICA) levels in serum of AS patients and healthy controls. Stable cell lines expressing four major MICA alleles (MICA*002, MICA*008, MICA*010 and MICA*019) in Taiwanese were used for biological analyses. We found that MICA*019 is the only major MICA allele significantly associated with AS susceptibility (PFDR = 2.25 × 10−115; OR, 14.90; 95% CI, 11.83–18.77) in Taiwanese. In addition, the MICA*019 allele is associated with syndesmophyte formation (PFDR = 0.0017; OR, 1.69; 95% CI, 1.29–2.22) and HLA-B27 positivity (PFDR = 1.45 × 10−33; OR, 28.79; 95% CI, 16.83–49.26) in AS patients. Serum sMICA levels were significantly increased in AS patients as compared to healthy controls. Additionally, MICA*019 homozygous subjects produced the highest levels of sMICA, compared to donors with other genotypes. Furthermore, in vitro experiments revealed that cells expressing MICA*019 produced the highest level of sMICA, as compared to other major MICA alleles. In summary, the MICA*019 allele, producing the highest levels of sMICA, is a significant risk factor for AS and syndesmophyte formation in Taiwanese. Our data indicate that a high level of sMICA is a biomarker for AS.

scholarly journals Focal Distribution of Baculovirus IE1 Triggered by Its Binding to the hr DNA Elements

2005 ◽  
Vol 79 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Toshihiro Nagamine ◽  
Yu Kawasaki ◽  
Tetsutaro Iizuka ◽  
Shogo Matsumoto
Keyword(s):  
Fluorescent Protein ◽  
Direct Repeat ◽  
Single Copy ◽  
Targeted Mutagenesis ◽  
Homologous Region ◽  
Focus Formation ◽  
Primary Determinant ◽  
Dna Elements ◽  
Species Specific ◽  
Green Fluorescent

ABSTRACT In BmN cells infected with the baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV), IE1, a principal transcriptional activator, localizes to sites of viral DNA replication. IE1 initially displays focal distribution in BmNPV-infected cells prior to DNA synthesis, whereas the protein expressed by transfection with the ie1 gene is distributed throughout the nucleoplasm instead of localized to discrete subnuclear structures. To identify the inducer of focus formation for IE1, we conducted transfection experiments with an IE1-GFP construct and found that cotransfection with genomic DNA fragments bearing the homologous region (hr) sequences caused the formation of IE1-green fluorescent protein (GFP) foci. The transfection of insect cells with a single plasmid containing exclusively the hr3 sequence and the IE1-GFP gene was sufficient to form IE1-GFP foci. These results suggest that hr elements are a primary determinant of the focal distribution of IE1. An analysis of a series of hr3 deletion mutants showed that a single copy of the direct repeat could induce the formation of IE1 foci. Targeted mutagenesis within the hr-binding domain of IE1-GFP caused impairment of the hr-dependent IE1 localization, suggesting that binding of IE1 to the hr elements is essential for the onset of IE1 focus formation. The observation of BmNPV IE1 foci in non-BmNPV-susceptible cells suggests that no species-specific factors are required for hr-dependent IE1 focus formation.

scholarly journals Evaluation of Four DNA Typing Techniques in Epidemiological Investigations of Bovine Tuberculosis

1998 ◽  
Vol 36 (1) ◽  
pp. 168-178 ◽  
Author(s):  
Debby Cousins ◽  
Suzette Williams ◽  
Ernesto Liébana ◽  
Alicia Aranaz ◽  
Annelies Bunschoten ◽  
...  
Keyword(s):  
Restriction Fragment ◽  
Dna Typing ◽  
Rflp Analysis ◽  
Direct Repeat ◽  
Single Copy ◽  
Epidemiological Evidence ◽  
Different Types ◽  
The Republic ◽  
Different Strains ◽  
Typing Technique

DNA fingerprinting techniques were used to type 273 isolates ofMycobacterium bovis from Australia, Canada, the Republic of Ireland, and Iran. The results of restriction fragment length polymorphism (RFLP) analysis with DNA probes from IS6110, the direct repeat (DR), and the polymorphic GC-rich sequence (PGRS) were compared with those of a new PCR-based method called spacer oligonucleotide typing (spoligotyping) developed for the rapid typing of Mycobacterium tuberculosis (J. Kamerbeek et al., J. Clin. Microbiol. 35:907–914, 1997). Eighty-five percent of the isolates harbored a single copy of IS6110, and 81.5% of these carried IS6110 on the characteristic 1.9-kb restriction fragment. RFLP analysis with IS6110 identified 23 different types, RFLP analysis with the DR probe identified 35 types, RFLP analysis with the PGRS probe identified 77 types, and the spoligotyping method identified 35 types. By combining all results, 99 different strains could be identified. Isolate clusters were frequently associated within herds or were found between herds when epidemiological evidence confirmed animal movements. RFLP analysis with IS6110 was sufficiently sensitive for the typing of isolates with more than three copies of IS6110, but RFLP analysis with the PGRS probe was the most sensitive typing technique for strains with only a single copy of IS6110. Spoligotyping may have advantages for the rapid typing of M. bovis, but it needs to be made more sensitive.

scholarly journals Trans-Species Polymorphism in Immune Genes: General Pattern or MHC-Restricted Phenomenon?

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Martin Těšický ◽  
Michal Vinkler
Keyword(s):  
Balancing Selection ◽  
General Pattern ◽  
Evolutionary Medicine ◽  
Present Species ◽  
Evolutionary Pattern ◽  
Immune Genes ◽  
Adaptive Introgression ◽  
Histocompatibility Complex ◽  
Innate Immune Genes ◽  
Immune Related Genes

Immunity exhibits extraordinarily high levels of variation. Evolution of the immune system in response to host-pathogen interactions in particular ecological contexts appears to be frequently associated with diversifying selection increasing the genetic variability. Many studies have documented that immunologically relevant polymorphism observed today may be tens of millions years old and may predate the emergence of present species. This pattern can be explained by the concept of trans-species polymorphism (TSP) predicting the maintenance and sharing of favourable functionally important alleles of immune-related genes between species due to ongoing balancing selection. Despite the generality of this concept explaining the long-lasting adaptive variation inherited from ancestors, current research in TSP has vastly focused only on major histocompatibility complex (MHC). In this review we summarise the evidence available on TSP in human and animal immune genes to reveal that TSP is not a MHC-specific evolutionary pattern. Further research should clearly pay more attention to the investigation of TSP in innate immune genes and especially pattern recognition receptors which are promising candidates for this type of evolution. More effort should also be made to distinguish TSP from convergent evolution and adaptive introgression. Identification of balanced TSP variants may represent an accurate approach in evolutionary medicine to recognise disease-resistance alleles.

scholarly journals Metronidazole Resistance in Prevotella spp. and Description of a New nim Gene in Prevotella baroniae

2009 ◽  
Vol 54 (1) ◽  
pp. 60-64 ◽  
Author(s):  
C. Alauzet ◽  
F. Mory ◽  
C. Teyssier ◽  
H. Hallage ◽  
J. P. Carlier ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Prolonged Exposure ◽  
Tertiary Care ◽  
Single Copy ◽  
Clinical Isolates ◽  
Teaching Hospitals ◽  
Rrna Gene ◽  
Prolonged Incubation ◽  
Sequence Elements ◽  
High Level

ABSTRACT Nonduplicate clinical isolates of Prevotella spp. recovered from patients hospitalized between 2003 and 2006 in two French tertiary-care teaching hospitals were investigated for their susceptibility to metronidazole and the presence of nim genes. Of the 188 strains tested, 3 isolates displayed reduced susceptibility to metronidazole after 48 h of incubation, while 27 additional isolates exhibited heterogeneous resistance after prolonged incubation; all 30 of the isolates were nim negative. Among the remaining 158 isolates, 7 nim-positive isolates were detected. All of these strains were identified as Prevotella baroniae by 16S rRNA gene sequence analysis and contained a new nim gene, named nimI, as determined by DNA sequence analysis. Chromosomal localization of this single-copy gene was demonstrated in all clinical isolates as well as in type strain P. baroniae DSM 16972 by using Southern hybridization. No known associated insertion sequence elements were detected upstream of the nimI gene in any of the nim-positive strains by PCR mapping. After prolonged exposure to metronidazole, stable resistant subpopulations could be selected in nimI-positive Prevotella isolates (n = 6) as well as in nim-negative Prevotella isolates (n = 6), irrespective of their initial susceptibility to this antibiotic. This study is the first description of a new nitroimidazole resistance gene in P. baroniae which seems to be silent and which might be intrinsic in this species. Moreover, our findings highlight the fact that high-level resistance to metronidazole may be easily induced in both nim-positive and nim-negative Prevotella sp. strains.

scholarly journals Molecular basis for the human erythrocyte glycophorin specifying the Miltenberger class I (MiI) phenotype

Blood ◽  
1992 ◽  
Vol 80 (1) ◽  
pp. 257-263 ◽  
Author(s):  
CH Huang ◽  
P Spruell ◽  
JJ Moulds ◽  
OO Blumenfeld
Keyword(s):  
Molecular Basis ◽  
Consensus Sequence ◽  
Direct Repeat ◽  
Single Copy ◽  
Class I ◽  
Blood Group System ◽  
White Family ◽  
Single Nucleotide ◽  
Single Nucleotide Change ◽  
Polymerase Chain

Abstract Human glycophorin Mil (HGpMil) is a structural variant of the MNSs blood group system that specifies the Miltenberger class I phenotype. We report here the molecular basis of the HGpMil gene identified in a white family in which the first homozygote was encountered. Immunoblotting analysis showed the expression of HGpMil and HGpB but the absence of HGpA on the homozygous Mil erythrocytes. Southern blot analysis detected no gross alterations in gene structure or band intensity. Genomic sequences encompassing exons II and III of the HGpMil gene were amplified by single-copy polymerase chain reaction. Restriction digestion and direct DNA sequence analysis showed that HGpMil gene is derived from an alpha N allele of HGpA and differs from the latter in the third exon by a single nucleotide change. In HGpMil, the presence of a deoxythymidine at the second position of codon 28 (ATG) not only resulted in a methionine substitution but also altered the consensus sequence for N-glycosylation from Asn-Asp-Thr to Asn-Asp- Met. These data are consistent with the occurrence of Mil on the red blood cell membrane as a variant deficient in the asparagine-linked carbohydrate unit. Significantly, this particular point mutation lies in between the two half-sites of a direct repeat that has been implicated to facilitate the recombination events leading to several other glycophorin genes of the Miltenberger series. Based on this relatedness, we propose an untemplated nucleotide replacement resulting from a gene conversion event as the molecular basis for the origin of HGpMil gene.

scholarly journals Genetic Analysis of Azole Resistance in the Darlington Strain of Candida albicans

2000 ◽  
Vol 44 (11) ◽  
pp. 2985-2990 ◽  
Author(s):  
Hiroshi Kakeya ◽  
Yoshitsugu Miyazaki ◽  
Haruko Miyazaki ◽  
Katherine Nyswaner ◽  
Brian Grimberg ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Candida Albicans ◽  
Amino Acid ◽  
Genetic Analysis ◽  
Expression System ◽  
Single Copy ◽  
Gene Replacement ◽  
Azole Resistance ◽  
High Level

ABSTRACT High-level azole resistance in the Darlington strain ofCandida albicans was investigated by gene replacement inC. albicans and expression in Saccharomyces cerevisiae. We sequenced the ERG11 gene, which encodes the sterol C14α-demethylase, from our copy of the Darlington strain. Both alleles contained the histidine for tyrosine substitution at position 132 (Y132H) reported in Darlington by others, but we also found a threonine-for-isoleucine substitution (I471T) not previously reported in the C. albicans ERG11. The encoded I471T change in amino acids conferred azole resistance when overexpressed alone and increased azole resistance when added to the Y132H amino acid sequence in an S. cerevisiae expression system. Replacement of one copy of ERG11 in an azole-susceptible strain of C. albicans with a single copy of the Darlington ERG11 resulted in expression of the integrated copy and a modest increase in azole resistance. The profound azole resistance of the Darlington strain is the result of multiple mutations.

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