Allelic diversity in an NLR gene BPH9 enables rice to combat planthopper variation.

PubMed

Zhao, Yan; Huang, Jin; Wang, Zhizheng; Jing, Shengli; Wang, Yang; Ouyang, Yidan; Cai, Baodong; Xin, Xiu-Fang; Liu, Xin; Zhang, Chunxiao; Pan, Yufang; Ma, Rui; Li, Qiaofeng; Jiang, Weihua; Zeng, Ya; Shangguan, Xinxin; Wang, Huiying; Du, Bo; Zhu, Lili; Xu, Xun; Feng, Yu-Qi; He, Sheng Yang; Chen, Rongzhi; Zhang, Qifa; He, Guangcun

2016-10-24

Brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most devastating insect pests of rice (Oryza sativa L.). Currently, 30 BPH-resistance genes have been genetically defined, most of which are clustered on specific chromosome regions. Here, we describe molecular cloning and characterization of a BPH-resistance gene, BPH9, mapped on the long arm of rice chromosome 12 (12L). BPH9 encodes a rare type of nucleotide-binding and leucine-rich repeat (NLR)-containing protein that localizes to the endomembrane system and causes a cell death phenotype. BPH9 activates salicylic acid- and jasmonic acid-signaling pathways in rice plants and confers both antixenosis and antibiosis to BPH. We further demonstrated that the eight BPH-resistance genes that are clustered on chromosome 12L, including the widely used BPH1, are allelic with each other. To honor the priority in the literature, we thus designated this locus as BPH1/9 These eight genes can be classified into four allelotypes, BPH1/9-1, -2, -7, and -9 These allelotypes confer varying levels of resistance to different biotypes of BPH. The coding region of BPH1/9 shows a high level of diversity in rice germplasm. Homologous fragments of the nucleotide-binding (NB) and leucine-rich repeat (LRR) domains exist, which might have served as a repository for generating allele diversity. Our findings reveal a rice plant strategy for modifying the genetic information to gain the upper hand in the struggle against insect herbivores. Further exploration of natural allelic variation and artificial shuffling within this gene may allow breeding to be tailored to control emerging biotypes of BPH.

A polyvalent hybrid protein elicits antibodies against the diverse allelic types of block 2 in Plasmodium falciparum merozoite surface protein 1.

PubMed

Tetteh, Kevin K A; Conway, David J

2011-10-13

Merozoite surface protein 1 (MSP1) of Plasmodium falciparum has been implicated as an important target of acquired immunity, and candidate components for a vaccine include polymorphic epitopes in the N-terminal polymorphic block 2 region. We designed a polyvalent hybrid recombinant protein incorporating sequences of the three major allelic types of block 2 together with a composite repeat sequence of one of the types and N-terminal flanking T cell epitopes, and compared this with a series of recombinant proteins containing modular sub-components and similarly expressed in Escherichia coli. Immunogenicity of the full polyvalent hybrid protein was tested in both mice and rabbits, and comparative immunogenicity studies of the sub-component modules were performed in mice. The full hybrid protein induced high titre antibodies against each of the major block 2 allelic types expressed as separate recombinant proteins and against a wide range of allelic types naturally expressed by a panel of diverse P. falciparum isolates, while the sub-component modules had partial antigenic coverage as expected. This encourages further development and evaluation of the full MSP1 block 2 polyvalent hybrid protein as a candidate blood-stage component of a malaria vaccine. Copyright © 2011 Elsevier Ltd. All rights reserved.

Employing genome-wide SNP discovery and genotyping strategy to extrapolate the natural allelic diversity and domestication patterns in chickpea

PubMed Central

Kujur, Alice; Bajaj, Deepak; Upadhyaya, Hari D.; Das, Shouvik; Ranjan, Rajeev; Shree, Tanima; Saxena, Maneesha S.; Badoni, Saurabh; Kumar, Vinod; Tripathi, Shailesh; Gowda, C. L. L.; Sharma, Shivali; Singh, Sube; Tyagi, Akhilesh K.; Parida, Swarup K.

2015-01-01

The genome-wide discovery and high-throughput genotyping of SNPs in chickpea natural germplasm lines is indispensable to extrapolate their natural allelic diversity, domestication, and linkage disequilibrium (LD) patterns leading to the genetic enhancement of this vital legume crop. We discovered 44,844 high-quality SNPs by sequencing of 93 diverse cultivated desi, kabuli, and wild chickpea accessions using reference genome- and de novo-based GBS (genotyping-by-sequencing) assays that were physically mapped across eight chromosomes of desi and kabuli. Of these, 22,542 SNPs were structurally annotated in different coding and non-coding sequence components of genes. Genes with 3296 non-synonymous and 269 regulatory SNPs could functionally differentiate accessions based on their contrasting agronomic traits. A high experimental validation success rate (92%) and reproducibility (100%) along with strong sensitivity (93–96%) and specificity (99%) of GBS-based SNPs was observed. This infers the robustness of GBS as a high-throughput assay for rapid large-scale mining and genotyping of genome-wide SNPs in chickpea with sub-optimal use of resources. With 23,798 genome-wide SNPs, a relatively high intra-specific polymorphic potential (49.5%) and broader molecular diversity (13–89%)/functional allelic diversity (18–77%) was apparent among 93 chickpea accessions, suggesting their tremendous applicability in rapid selection of desirable diverse accessions/inter-specific hybrids in chickpea crossbred varietal improvement program. The genome-wide SNPs revealed complex admixed domestication pattern, extensive LD estimates (0.54–0.68) and extended LD decay (400–500 kb) in a structured population inclusive of 93 accessions. These findings reflect the utility of our identified SNPs for subsequent genome-wide association study (GWAS) and selective sweep-based domestication trait dissection analysis to identify potential genomic loci (gene-associated targets) specifically

Diversity of alleles encoding HLA-B40: relative frequencies in united states populations and description of five novel alleles.

PubMed

Pimtanothai, N; Rizzuto, G A; Slack, R; Steiner, N K; Kosman, C A; Jones, P F; Koester, R; Ng, J; Hartzman, R J; Katovich Hurley, C

2000-08-01

The frequency of each B*40 allele was determined by DNA sequencing in four major United States populations: Caucasians, African Americans, Asians/Pacific Islanders, and Hispanics. Thirty-two individuals from each ethnic group, who were previously described serologically as B40, B60, or B61, were randomly selected out of a pool of 82,979 unrelated individuals for allele characterization. Out of nine different B*40 alleles identified in this study, B*4001 and B*4002 were the two most frequent B*40 alleles in all the population groups. B*4001 was the primary B*40 allele seen in Caucasians (83%) and African Americans (76%), while B*4002 was found in the majority of Hispanics (62%). The distributions of both alleles were comparable in the Asian/Pacific Islander population. These two alleles were the only B*40 alleles detected in Caucasians while four to five additional B*40 alleles were seen in the other population groups. The other B*40 alleles detected in this study included: B*4003 and B*4010 in Asian/Pacific Islanders; B*4012 and B*4016 in African Americans; and B*4004, B*4006, and B*4027 in Hispanics. Analysis revealed significant differences between Hispanics and all other groups as well as between African Americans and Asian/Pacific Islanders. This report also describes five novel B*40 alleles: B*4019, B*4020, B*4024, B*4027, and B*4028.

Investigating the relationship between FMR1 allele length and cognitive ability in children: a subtle effect of the normal allele range on the normal ability range?

PubMed

Loat, C S; Craig, G; Plomin, R; Craig, I W

2006-09-01

The FMR1 gene contains a trinucleotide repeat tract which can expand from a normal size of around 30 repeats to over 200 repeats, causing mental retardation (Fragile X Syndrome). Evidence suggests that premutation males (55-200 repeats) are susceptible to a late-onset tremor/ataxia syndrome and females to premature ovarian failure, and that intermediate alleles ( approximately 41-55 repeats) and premutations may be in excess in samples with special educational needs. We explored the relationship between FMR1 allele length and cognitive ability in 621 low ability and control children assessed at 4 and 7 years, as well as 122 students with high IQ. The low and high ability and control samples showed no between-group differences in incidence of longer alleles. In males there was a significant negative correlation between allele length and non-verbal ability at 4 years (p = 0.048), academic achievement in maths (p = 0.003) and English (p = 0.011) at 7 years, and IQ in the high ability group (p = 0.018). There was a significant negative correlation between allele length and a standardised score for IQ and general cognitive ability at age 7 in the entire male sample (p = 0.002). This suggests that, within the normal spectrum of allele length, increased repeat numbers may have a limiting influence on cognitive performance.

DRD4 dopamine receptor allelic diversity in various primate species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamson, M.; Higley, D.; O`Brien, S.

The DRD4 dopamine receptor is uniquely characterized by a 48 bp repeating segment within the coding region, located in exon III. Different DRD4 alleles are produced by the presence of additional 48 bp repeats, each of which adds 16 amino acids to the length of the 3rd intracytoplasmic loop of the receptor. The DRD4 receptor is therefore an intriguing candidate gene for behaviors which are influenced by dopamine function. In several human populations, DRD4 alleles with 2-8 and 10 repeats have previously been identified, and the 4 and 7 repeat alleles are the most abundant. We have determined DRD4 genotypesmore » in the following nonhuman primate species: chimpanzee N=2, pygmy chimpanzee N=2, gorilla N=4, siamang N=2, Gelada baboon N=1, gibbon N=1, orangutan (Bornean and Sumatran) N=62, spider monkey N=4, owl monkey N=1, Colobus monkey N=1, Patas monkey N=1, ruffed lemur N=1, rhesus macaque N=8, and vervet monkey N=28. The degree of DRD4 polymorphism and which DRD4 alleles were present both showed considerable variation across primate species. In contrast to the human, rhesus macaque monkeys were monomorphic. The 4 and 7 repeat allels, highly abundant in the human, may not be present in certain other primates. For example, the four spider monkeys we studied showed the 7, 8 and 9 repeat length alleles and the only gibbon we analyzed was homozygous for the 9 repeat allele (thus far not observed in the human). Genotyping of other primate species and sequencing of the individual DRD4 repeat alleles in different species may help us determine the ancestral DRD4 repeat length and identify connections between DRD4 genotype and phenotype.« less

Plasmodium falciparum msp1 and msp2 genetic diversity and allele frequencies in parasites isolated from symptomatic malaria patients in Bobo-Dioulasso, Burkina Faso.

PubMed

Somé, Anyirékun Fabrice; Bazié, Thomas; Zongo, Issaka; Yerbanga, R Serge; Nikiéma, Frédéric; Neya, Cathérine; Taho, Liz Karen; Ouédraogo, Jean-Bosco

2018-05-30

In Burkina Faso, malaria remains the overall leading cause of morbidity and mortality accounting for 35.12% of consultations, 40.83% of hospitalizations and 37.5% of deaths. Genotyping of malaria parasite populations remains an important tool to determine the types and number of parasite clones in an infection. The present study aimed to evaluate the merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) genetic diversity and allele frequencies in Bobo-Dioulasso, Burkina Faso. Dried blood spots (DBS) were collected at baseline from patients with uncomplicated malaria in urban health centers in Bobo-Dioulasso. Parasite DNA was extracted using chelex-100 and species were identified using nested PCR. Plamodium falciparum msp1 and msp2 genes were amplified by nested polymerase chain reaction (PCR) and PCR products were analyzed by electrophoresis on a 2.5% agarose gel. Alleles were categorized according to their molecular weight. A total of 228 blood samples were analyzed out of which 227 (99.9%) were confirmed as P. falciparum-positive and one sample classified as mixed infection for P. malaria and P. falciparum. In msp1, the K1 allelic family was predominant with 77.4% (162/209) followed respectively by the MAD20 allelic family with 41.3% and R033 allelic family with 36%. In msp2, the 3D7 allelic family was the most frequently detected with 93.1 % compared to FC27 with 41.3%. Twenty-one different alleles were observed in msp1 with 9 alleles for K1, 8 alleles for MAD20 and 4 alleles for R033. In msp2, 25 individual alleles were detected with 10 alleles for FC27 and 15 alleles for 3D7. The mean multiplicity of falciparum infection was 1.95 with respectively 1.8 (1.76-1.83) and 2.1 (2.03-2.16) for msp1 and msp2 (P = 0.01). Our study showed high genetic diversity and allelic frequencies of msp1 and msp2 in Plasmodium falciparum isolates from symptomatic malaria patients in Bobo-Dioulasso.

Novel CRISPR/Cas9 gene drive constructs reveal insights into mechanisms of resistance allele formation and drive efficiency in genetically diverse populations

PubMed Central

Liu, Chen

2017-01-01

A functioning gene drive system could fundamentally change our strategies for the control of vector-borne diseases by facilitating rapid dissemination of transgenes that prevent pathogen transmission or reduce vector capacity. CRISPR/Cas9 gene drive promises such a mechanism, which works by converting cells that are heterozygous for the drive construct into homozygotes, thereby enabling super-Mendelian inheritance. Although CRISPR gene drive activity has already been demonstrated, a key obstacle for current systems is their propensity to generate resistance alleles, which cannot be converted to drive alleles. In this study, we developed two CRISPR gene drive constructs based on the nanos and vasa promoters that allowed us to illuminate the different mechanisms by which resistance alleles are formed in the model organism Drosophila melanogaster. We observed resistance allele formation at high rates both prior to fertilization in the germline and post-fertilization in the embryo due to maternally deposited Cas9. Assessment of drive activity in genetically diverse backgrounds further revealed substantial differences in conversion efficiency and resistance rates. Our results demonstrate that the evolution of resistance will likely impose a severe limitation to the effectiveness of current CRISPR gene drive approaches, especially when applied to diverse natural populations. PMID:28727785

MHC-mediated sexual selection on birdsong: Generic polymorphism, particular alleles and acoustic signals.

PubMed

Garamszegi, László Zsolt; Zagalska-Neubauer, Magdalena; Canal, David; Blázi, György; Laczi, Miklós; Nagy, Gergely; Szöllősi, Eszter; Vaskuti, Éva; Török, János; Zsebők, Sándor

2018-06-01

Several hypotheses predict that the major histocompatibility complex (MHC) drives mating preference in females. Olfactory, colour or morphological traits are often found as reliable signals of the MHC profile, but the role of avian song mediating MHC-based female choice remains largely unexplored. We investigated the relationship between several MHC and acoustic features in the collared flycatcher (Ficedula albicollis), a European passerine with complex songs. We screened a fragment of the class IIB second exon of the MHC molecule, of which individuals harbour 4-15 alleles, while considerable sequence diversity is maintained at the population level. To make statistical inferences from a large number of comparisons, we adopted both null-hypothesis testing and effect size framework in combination with randomization procedures. After controlling for potential confounding factors, neither MHC allelic diversity nor the presence of particular alleles was associated remarkably with the investigated qualitative and quantitative song traits. Furthermore, genetic similarity among males based on MHC sequences was not reflected by the similarity in their song based on syllable content. Overall, these results suggest that the relationship between features of song and the allelic composition and diversity of MHC is not strong in the studied species. However, a biologically motivated analysis revealed that individuals that harbour an MHC allele that impairs survival perform songs with broader frequency range. This finding suggests that certain aspects of the song may bear reliable information concerning the MHC profile of the individuals, which can be used by females to optimize mate choice. © 2018 John Wiley & Sons Ltd.

Two colonisation stages generate two different patterns of genetic diversity within native and invasive ranges of Ulex europaeus

PubMed Central

Hornoy, B; Atlan, A; Roussel, V; Buckley, Y M; Tarayre, M

2013-01-01

Genetic diversity and the way a species is introduced influence the capacity of populations of invasive species to persist in, and adapt to, their new environment. The diversity of introduced populations affects their evolutionary potential, which is particularly important for species that have invaded a wide range of habitats and climates, such as European gorse, Ulex europaeus. This species originated in the Iberian peninsula and colonised Europe in the Neolithic; over the course of the past two centuries it was introduced to, and has become invasive in, other continents. We characterised neutral genetic diversity and its structure in the native range and in invaded regions. By coupling these results with historical data, we have identified the way in which gorse populations were introduced and the consequences of introduction history on genetic diversity. Our study is based on the genotyping of individuals from 18 populations at six microsatellite loci. As U. europaeus is an allohexaploid species, we used recently developed tools that take into account genotypic ambiguity. Our results show that genetic diversity in gorse is very high and mainly contained within populations. We confirm that colonisation occurred in two stages. During the first stage, gorse spread out naturally from Spain towards northern Europe, losing some genetic diversity. During the second stage, gorse was introduced by humans into different regions of the world, from northern Europe. These introductions resulted in the loss of rare alleles but did not significantly reduce genetic diversity and thus the evolutionary potential of this invasive species. PMID:23759725

Two colonisation stages generate two different patterns of genetic diversity within native and invasive ranges of Ulex europaeus.

PubMed

Hornoy, B; Atlan, A; Roussel, V; Buckley, Y M; Tarayre, M

2013-11-01

Genetic diversity and the way a species is introduced influence the capacity of populations of invasive species to persist in, and adapt to, their new environment. The diversity of introduced populations affects their evolutionary potential, which is particularly important for species that have invaded a wide range of habitats and climates, such as European gorse, Ulex europaeus. This species originated in the Iberian peninsula and colonised Europe in the Neolithic; over the course of the past two centuries it was introduced to, and has become invasive in, other continents. We characterised neutral genetic diversity and its structure in the native range and in invaded regions. By coupling these results with historical data, we have identified the way in which gorse populations were introduced and the consequences of introduction history on genetic diversity. Our study is based on the genotyping of individuals from 18 populations at six microsatellite loci. As U. europaeus is an allohexaploid species, we used recently developed tools that take into account genotypic ambiguity. Our results show that genetic diversity in gorse is very high and mainly contained within populations. We confirm that colonisation occurred in two stages. During the first stage, gorse spread out naturally from Spain towards northern Europe, losing some genetic diversity. During the second stage, gorse was introduced by humans into different regions of the world, from northern Europe. These introductions resulted in the loss of rare alleles but did not significantly reduce genetic diversity and thus the evolutionary potential of this invasive species.

Allelic diversity of the MHC class II DRB genes in brown bears (Ursus arctos) and a comparison of DRB sequences within the family Ursidae.

PubMed

Goda, N; Mano, T; Kosintsev, P; Vorobiev, A; Masuda, R

2010-11-01

The allelic diversity of the DRB locus in major histocompatibility complex (MHC) genes was analyzed in the brown bear (Ursus arctos) from the Hokkaido Island of Japan, Siberia, and Kodiak of Alaska. Nineteen alleles of the DRB exon 2 were identified from a total of 38 individuals of U. arctos and were highly polymorphic. Comparisons of non-synonymous and synonymous substitutions in the antigen-binding sites of deduced amino acid sequences indicated evidence for balancing selection on the bear DRB locus. The phylogenetic analysis of the DRB alleles among three genera (Ursus, Tremarctos, and Ailuropoda) in the family Ursidae revealed that DRB allelic lineages were not separated according to species. This strongly shows trans-species persistence of DRB alleles within the Ursidae. © 2010 John Wiley & Sons A/S.

Meiotic recombination generates rich diversity in NK cell receptor genes, alleles, and haplotypes

PubMed Central

Norman, Paul J.; Abi-Rached, Laurent; Gendzekhadze, Ketevan; Hammond, John A.; Moesta, Achim K.; Sharma, Deepti; Graef, Thorsten; McQueen, Karina L.; Guethlein, Lisbeth A.; Carrington, Christine V.F.; Chandanayingyong, Dasdayanee; Chang, Yih-Hsin; Crespí, Catalina; Saruhan-Direskeneli, Güher; Hameed, Kamran; Kamkamidze, Giorgi; Koram, Kwadwo A.; Layrisse, Zulay; Matamoros, Nuria; Milà, Joan; Park, Myoung Hee; Pitchappan, Ramasamy M.; Ramdath, D. Dan; Shiau, Ming-Yuh; Stephens, Henry A.F.; Struik, Siske; Tyan, Dolly; Verity, David H.; Vaughan, Robert W.; Davis, Ronald W.; Fraser, Patricia A.; Riley, Eleanor M.; Ronaghi, Mostafa; Parham, Peter

2009-01-01

Natural killer (NK) cells contribute to the essential functions of innate immunity and reproduction. Various genes encode NK cell receptors that recognize the major histocompatibility complex (MHC) Class I molecules expressed by other cells. For primate NK cells, the killer-cell immunoglobulin-like receptors (KIR) are a variable and rapidly evolving family of MHC Class I receptors. Studied here is KIR3DL1/S1, which encodes receptors for highly polymorphic human HLA-A and -B and comprises three ancient allelic lineages that have been preserved by balancing selection throughout human evolution. While the 3DS1 lineage of activating receptors has been conserved, the two 3DL1 lineages of inhibitory receptors were diversified through inter-lineage recombination with each other and with 3DS1. Prominent targets for recombination were D0-domain polymorphisms, which modulate enhancer function, and dimorphism at position 283 in the D2 domain, which influences inhibitory function. In African populations, unequal crossing over between the 3DL1 and 3DL2 genes produced a deleted KIR haplotype in which the telomeric “half” was reduced to a single fusion gene with functional properties distinct from its 3DL1 and 3DL2 parents. Conversely, in Eurasian populations, duplication of the KIR3DL1/S1 locus by unequal crossing over has enabled individuals to carry and express alleles of all three KIR3DL1/S1 lineages. These results demonstrate how meiotic recombination combines with an ancient, preserved diversity to create new KIR phenotypes upon which natural selection acts. A consequence of such recombination is to blur the distinction between alleles and loci in the rapidly evolving human KIR gene family. PMID:19411600

Extreme MHC class I diversity in the sedge warbler (Acrocephalus schoenobaenus); selection patterns and allelic divergence suggest that different genes have different functions.

PubMed

Biedrzycka, Aleksandra; O'Connor, Emily; Sebastian, Alvaro; Migalska, Magdalena; Radwan, Jacek; Zając, Tadeusz; Bielański, Wojciech; Solarz, Wojciech; Ćmiel, Adam; Westerdahl, Helena

2017-07-05

Recent work suggests that gene duplications may play an important role in the evolution of immunity genes. Passerine birds, and in particular Sylvioidea warblers, have highly duplicated major histocompatibility complex (MHC) genes, which are key in immunity, compared to other vertebrates. However, reasons for this high MHC gene copy number are yet unclear. High-throughput sequencing (HTS) allows MHC genotyping even in individuals with extremely duplicated genes. This HTS data can reveal evidence of selection, which may help to unravel the putative functions of different gene copies, i.e. neofunctionalization. We performed exhaustive genotyping of MHC class I in a Sylvioidea warbler, the sedge warbler, Acrocephalus schoenobaenus, using the Illumina MiSeq technique on individuals from a wild study population. The MHC diversity in 863 genotyped individuals by far exceeds that of any other bird species described to date. A single individual could carry up to 65 different alleles, a large proportion of which are expressed (transcribed). The MHC alleles were of three different lengths differing in evidence of selection, diversity and divergence within our study population. Alleles without any deletions and alleles containing a 6 bp deletion showed characteristics of classical MHC genes, with evidence of multiple sites subject to positive selection and high sequence divergence. In contrast, alleles containing a 3 bp deletion had no sites subject to positive selection and had low divergence. Our results suggest that sedge warbler MHC alleles that either have no deletion, or contain a 6 bp deletion, encode classical antigen presenting MHC molecules. In contrast, MHC alleles containing a 3 bp deletion may encode molecules with a different function. This study demonstrates that highly duplicated MHC genes can be characterised with HTS and that selection patterns can be useful for revealing neofunctionalization. Importantly, our results highlight the need to consider the

Genetic Diversity within a Global Panel of Durum Wheat (Triticum durum) Landraces and Modern Germplasm Reveals the History of Alleles Exchange.

PubMed

Kabbaj, Hafssa; Sall, Amadou T; Al-Abdallat, Ayed; Geleta, Mulatu; Amri, Ahmed; Filali-Maltouf, Abdelkarim; Belkadi, Bouchra; Ortiz, Rodomiro; Bassi, Filippo M

2017-01-01

Durum wheat is the 10th most important crop in the world, and its use traces back to the origin of agriculture. Unfortunately, in the last century only part of the genetic diversity available for this species has been captured in modern varieties through breeding. Here, the population structure and genetic diversity shared among elites and landraces collected from 32 countries was investigated. A total of 370 entries were genotyped with Axiom 35K array to identify 8,173 segregating single nucleotide polymorphisms (SNPs). Of these, 500 were selected as highly informative with a PIC value above 0.32 and used to test population structure via DAPC, STRUCTURE, and neighbor joining tree. A total of 10 sub-populations could be identified, six constituted by modern germplasm and four by landraces of different geographical origin. Interestingly, genomic comparison among groups indicated that Middle East and Ethiopia had the lowest level of allelic diversity, while breeding programs and landraces collected outside these regions were the richest in rare alleles. Further, phylogenetic analysis among landraces indicated that Ethiopia might represent a second center of origin of durum wheat, rather than a second domestication site as previously believed. Together, the analyses carried here provide a global picture of the available genetic diversity for this crop and shall guide its targeted use by breeders.

Extensive diversity in the allelic frequency of Plasmodium falciparum merozoite surface proteins and glutamate-rich protein in rural and urban settings of southwestern Nigeria.

PubMed

Funwei, Roland I; Thomas, Bolaji N; Falade, Catherine O; Ojurongbe, Olusola

2018-01-02

Nigeria carries a high burden of malaria which makes continuous surveillance for current information on genetic diversity imperative. In this study, the merozoite surface proteins (msp-1, msp-2) and glutamate-rich protein (glurp) of Plasmodium falciparum collected from two communities representing rural and urban settings in Ibadan, southwestern Nigeria were analysed. A total of 511 febrile children, aged 3-59 months, whose parents/guardians provided informed consent, were recruited into the study. Capillary blood was obtained for malaria rapid diagnostic test, thick blood smears for parasite count and blood spots on filter paper for molecular analysis. Three-hundred and nine samples were successfully genotyped for msp-1, msp-2 and glurp genes. The allelic distribution of the three genes was not significantly different in the rural and urban communities. R033 and 3D7 were the most prevalent alleles in both rural and urban communities for msp-1 and msp-2, respectively. Eleven of glurp RII region genotypes, coded I-XII, with sizes ranging from 500 to 1100 base pairs were detected in the rural setting. Genotype XI (1000-1050 bp) had the highest prevalence of 41.5 and 38.5% in rural and urban settings, respectively. Overall, 82.1 and 70.0% of samples had multiclonal infection with msp-1 gene resulting in a mean multiplicity of infection (MOI) of 2.8 and 2.6 for rural and urban samples, respectively. Msp-1 and msp-2 genes displayed higher levels of diversity and higher MOI rates than the glurp gene. Significant genetic diversity was observed between rural and urban parasite populations in Ibadan, southwestern Nigeria. The results of this study show that malaria transmission intensity in these regions is still high. No significant difference was observed between rural and urban settings, except for a completely different msp-1 allele, compared to previous reports, thereby confirming the changing face of malaria transmission in these communities. This study provides

Global distribution of malaria-resistant MHC-HLA alleles: the number and frequencies of alleles and malaria risk.

PubMed

Garamszegi, László Zsolt

2014-09-03

The major histocompatibility complex (MHC) is the most polymorphic genetic region in vertebrates, but the origin of such genetic diversity remains unresolved. Several studies have demonstrated at the within-population level that individuals harbouring particular alleles can be less or more susceptible to malaria, but these do not allow strong generalization. Here worldwide data on the frequencies of several hundred MHC alleles of the human leucocyte antigen (HLA) system in relation to malaria risk at the between-population level were analysed in a phylogenetic framework, and results for different alleles were quantitatively summarized in a meta-analysis. There was an overall positive relationship between malaria pressure and the frequency of several HLA alleles indicating that allele frequencies increase in countries with strong malaria pressure. Nevertheless, considerable heterogeneity was observed across alleles, and some alleles showed a remarkable negative relationship with malaria risk. When heterogeneities were partitioned into different organization groups of the MHC, the strongest positive relationships were detected for alleles of the HLA-A and HLA-B loci, but there were also differences between MHC supertypes that constitute functionally distinct nucleotide sequences. Finally, the number of MHC alleles that are maintained within countries was also related to malaria risk. Therefore, malaria represents a key selection pressure for the human MHC and has left clear evolutionary footprints on both the frequencies and the number of alleles observed in different countries.

A Computer Simulation Study of Vntr Population Genetics: Constrained Recombination Rules Out the Infinite Alleles Model

PubMed Central

Harding, R. M.; Boyce, A. J.; Martinson, J. J.; Flint, J.; Clegg, J. B.

1993-01-01

Extensive allelic diversity in variable numbers of tandem repeats (VNTRs) has been discovered in the human genome. For population genetic studies of VNTRs, such as forensic applications, it is important to know whether a neutral mutation-drift balance of VNTR polymorphism can be represented by the infinite alleles model. The assumption of the infinite alleles model that each new mutant is unique is very likely to be violated by unequal sister chromatid exchange (USCE), the primary process believed to generate VNTR mutants. We show that increasing both mutation rates and misalignment constraint for intrachromosomal recombination in a computer simulation model reduces simulated VNTR diversity below the expectations of the infinite alleles model. Maximal constraint, represented as slippage of single repeats, reduces simulated VNTR diversity to levels expected from the stepwise mutation model. Although misalignment rule is the more important variable, mutation rate also has an effect. At moderate rates of USCE, simulated VNTR diversity fluctuates around infinite alleles expectation. However, if rates of USCE are high, as for hypervariable VNTRs, simulated VNTR diversity is consistently lower than predicted by the infinite alleles model. This has been observed for many VNTRs and accounted for by technical problems in distinguishing alleles of neighboring size classes. We use sampling theory to confirm the intrinsically poor fit to the infinite alleles model of both simulated VNTR diversity and observed VNTR polymorphisms sampled from two Papua New Guinean populations. PMID:8293988

A computer simulation study of VNTR population genetics: constrained recombination rules out the infinite alleles model.

PubMed

Harding, R M; Boyce, A J; Martinson, J J; Flint, J; Clegg, J B

1993-11-01

Extensive allelic diversity in variable numbers of tandem repeats (VNTRs) has been discovered in the human genome. For population genetic studies of VNTRs, such as forensic applications, it is important to know whether a neutral mutation-drift balance of VNTR polymorphism can be represented by the infinite alleles model. The assumption of the infinite alleles model that each new mutant is unique is very likely to be violated by unequal sister chromatid exchange (USCE), the primary process believed to generate VNTR mutants. We show that increasing both mutation rates and misalignment constraint for intrachromosomal recombination in a computer simulation model reduces simulated VNTR diversity below the expectations of the infinite alleles model. Maximal constraint, represented as slippage of single repeats, reduces simulated VNTR diversity to levels expected from the stepwise mutation model. Although misalignment rule is the more important variable, mutation rate also has an effect. At moderate rates of USCE, simulated VNTR diversity fluctuates around infinite alleles expectation. However, if rates of USCE are high, as for hypervariable VNTRs, simulated VNTR diversity is consistently lower than predicted by the infinite alleles model. This has been observed for many VNTRs and accounted for by technical problems in distinguishing alleles of neighboring size classes. We use sampling theory to confirm the intrinsically poor fit to the infinite alleles model of both simulated VNTR diversity and observed VNTR polymorphisms sampled from two Papua New Guinean populations.

The population genetics of sporophytic self-incompatibility in Senecio squalidus L. (Asteraceae): the number, frequency, and dominance interactions of S alleles across its British range.

PubMed

Brennan, Adrian C; Harris, Stephen A; Hiscock, Simon J

2006-02-01

Sporophytic self-incompatibility (SSI) was studied in 11 British Senecio squalidus populations to quantify mating system variation and determine how its recent colonization of the United Kingdom has influenced its mating behavior. S allele number, frequency, and dominance interactions in populations were assessed using full diallels of controlled pollinations. A mean of 5.1 S alleles per population was observed, and no population contained more than six S alleles. Numbers of S alleles within populations of S. squalidus declined with increasing distance from the center of its introduction (Oxford). Cross-classification of S alleles allowed an estimate of approximately seven and no more than 11 S alleles for the entire British S. squalidus population. The low number of S alleles observed in British S. squalidus compared to other SI species is consistent with the population bottleneck associated with S. squalidus' introduction to the Oxford Botanic Garden and subsequent colonization of Britain. Extensive S allele dominance interactions were observed to be a feature of the S. squalidus SSI system and may represent an adaptive response to improve limited mate availability imposed by the presence of so few S alleles. Multilocus allozyme genotypes were also identified for individuals in all populations and geographic patterns of S locus and allozyme loci variation investigated. Less interpopulation structure was observed for the S locus than for allozyme diversity--a finding indicative of the effects of negative frequency-dependent selection at the S locus maintaining equal S phenotypes within populations and enhancing effective migration between populations.

A computer simulation study of VNTR population genetics: Constrained recombination rules out the infinite alleles model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harding, R.M.; Martinson, J.J.; Flint, J.

1993-11-01

Extensive allelic diversity in variable numbers of tandem repeats (VNTRs) has been discovered in the human genome. For population genetic studies of VNTRs, such as forensic applications, it is important to know whether a neutral mutation-drift balance of VNTR polymorphism can be represented by the infinite alleles model. The assumption of the infinite alleles model that each new mutant is unique is very likely to be violated by unequal sister chromatid exchange (USCE), the primary process believed to generate VNTR mutants. The authors show that increasing both mutation rates and misalignment constraint for intrachromosomal recombination in a computer simulation modelmore » reduces simulated VNTR diversity below the expectations of the infinite alleles model. Maximal constraint, represented as slippage of single repeats, reduces simulated VNTR diversity to levels expected from the stepwise mutation model. Although misalignment rule is the more important variable, mutation rate also has an effect. At moderate rates of USCE, simulated VNTR diversity fluctuates around infinite alleles expectation. However, if rates of USCE are high, as for hypervariable VNTRs, simulated VNTR diversity is consistently lower than predicted by the infinite alleles model. This has been observed for many VNTRs and accounted for by technical problems in distinguishing alleles of neighboring size classes. The authors use sampling theory to confirm the intrinsically poor fit to the infinite model of both simulated VNTR diversity and observed VNTR polymorphisms sampled from two Papua New Guinean populations. 25 refs., 20 figs., 4 tabs.« less

Allelic and haplotypic diversity of HLA-A, -B, -C, -DRB1, and -DQB1 genes in the Korean population.

PubMed

Lee, K W; Oh, D H; Lee, C; Yang, S Y

2005-05-01

High-resolution human leukocyte antigen (HLA) typing exposes the unique patterns of HLA allele and haplotype frequencies in each population. In this study, HLA-A, -B, -C, -DRB1, and -DQB1 genotypes were analyzed in 485 apparently unrelated healthy Korean individuals. A total of 20 HLA-A, 43 HLA-B, 21 HLA-C, 31 HLA-DRB1, and 14 HLA-DQB1 alleles were identified. Eleven alleles (A*0201, A*1101, A*2402, A*3303, B*1501, Cw*0102, Cw*0302, Cw*0303, DQB1*0301, DQB1*0302, and DQB1*0303) were found in more than 10% of the population. In each serologic group, a maximum of three alleles were found with several exceptions (A2, B62, DR4, DR14, and DQ6). In each serologic group exhibiting multiple alleles, two major alleles were present at 62-96% (i.e. A*0201 and A*0206 comprise 85% of A2-positive alleles). Multiple-locus haplotypes estimated by the maximum likelihood method revealed 51 A-C, 43 C-B, 52 B-DRB1, 34 DRB1-DQB1, 48 A-C-B, 42 C-B-DRB1, 46 B-DRB1-DQB1, and 30 A-C-B-DRB1-DQB1 haplotypes with frequencies of more than 0.5%. In spite of their high polymorphism in B and DRB1, identification of relatively small numbers of two-locus (B-C and DRB1-DQB1) haplotypes suggested strong associations of those two loci, respectively. Five-locus haplotypes defined by high-resolution DNA typing correlated well with previously identified serology-based haplotypes in the population. The five most frequent haplotypes were: A*3303-Cw*1403-B*4403-DRB1*1302-DQB1*0604 (4.2%), A*3303-Cw*0701/6-B*4403-DRB1*0701-DQB1*0201/2 (3.0%), A*3303-Cw*0302-B*5801-DRB1*1302-DQB1*0609 (3.0%), A*2402-Cw*0702-B*0702-DRB1*0101-DQB1*0501 (2.9%), and A*3001-Cw*0602-B*1302-DRB1*0701-DQB1*0201/2 (2.7%). Several sets of allele level haplotypes that could not be discriminated by routine HLA-A, -B, and -DRB1 low-resolution typing originated from allelic diversity of A2, B61, DR4, and DR8 serologic groups. Information obtained in this study will be useful for medical and forensic applications as well as in anthropology.

Molecular basis of the allelic inheritance of rabbit immunoglobulin VH allotypes: implications for the generation of antibody diversity.

PubMed

Knight, K L; Becker, R S

1990-03-23

Rabbits are unique in that their immunoglobulin VH regions bear allotypic markers encoded by allelic genes. The presence of these markers on most serum immunoglobulins is difficult to explain, as the germline contains several hundred VH genes. We cloned VH genes from normal rabbits of the VHa allotypes a1, a2, and a3 and from a mutant a2 rabbit, Alicia, which expresses almost no a2 allotype. The D-proximal VH gene VH1 of normal rabbits encoded prototype a1, a2, or a3 allotype VH regions in a1, a2, or a3 rabbits, respectively; VH1 was shown to be preferentially utilized in leukemic rabbit B cells. This VH1 gene was deleted from the germline of the Alicia rabbit. These data suggest that the allelic inheritance of a allotypes results from preferential utilization of VH1 in VDJ rearrangements. We suggest that antibody diversity in rabbit primarily results from somatic hypermutation and gene conversion.

Allelic variation contributes to bacterial host specificity

DOE PAGES

Yue, Min; Han, Xiangan; Masi, Leon De; ...

2015-10-30

Understanding the molecular parameters that regulate cross-species transmission and host adaptation of potential pathogens is crucial to control emerging infectious disease. Although microbial pathotype diversity is conventionally associated with gene gain or loss, the role of pathoadaptive nonsynonymous single-nucleotide polymorphisms (nsSNPs) has not been systematically evaluated. Here, our genome-wide analysis of core genes within Salmonella enterica serovar Typhimurium genomes reveals a high degree of allelic variation in surface-exposed molecules, including adhesins that promote host colonization. Subsequent multinomial logistic regression, MultiPhen and Random Forest analyses of known/suspected adhesins from 580 independent Typhimurium isolates identifies distinct host-specific nsSNP signatures. Moreover, population andmore » functional analyses of host-associated nsSNPs for FimH, the type 1 fimbrial adhesin, highlights the role of key allelic residues in host-specific adherence in vitro. In conclusion, together, our data provide the first concrete evidence that functional differences between allelic variants of bacterial proteins likely contribute to pathoadaption to diverse hosts.« less

Population genetics of sporophytic self-incompatibility in Senecio squalidus L. (Asteraceae) II: a spatial autocorrelation approach to determining mating behaviour in the presence of low S allele diversity.

PubMed

Brennan, A C; Harris, S A; Hiscock, S J

2003-11-01

We recently estimated that as few as six S alleles represent the extent of S locus diversity in a British population of the self-incompatible (SI) coloniser Senecio squalidus (Oxford Ragwort). Despite the predicted constraints to mating imposed by such a low number of S alleles, S. squalidus maintains a strong sporophytic self-incompatibility (SSI) system and there is no evidence for a breakdown of SSI or any obvious negative reproductive consequences for this highly successful coloniser. The present paper assesses mating behaviour in an Oxford S. squalidus population through observations of its effect on spatial patterns of genetic diversity and thus the extent to which it is responsible for ameliorating the potentially detrimental reproductive consequences of low S allele diversity in British S. squalidus. A spatial autocorrelation (SA) treatment of S locus and allozyme polymorphism data for four loci indicates that mating events regularly occur at all the distance classes examined from 60 to 480 m throughout the entire sample population. Less SA is observed for S locus data than for allozyme data in accordance with the hypothesis that SSI and low diversity at the S locus are driving these large-scale mating events. The limited population structure at small distances of 60 m and less observed for SA analysis of the Me-2 locus and by F-statistics for all the allozyme data, is evidence of some local relatedness due to limited seed and pollen dispersal in S. squalidus. However, the overall impression of mating dynamics in this S. squalidus population is that of ample potential mating opportunities with many individuals at large population scales, indicating that reproductive success is not seriously affected by few S alleles available for mating interactions.

Expanding diversity at the HLA-B locus: 28 novel HLA-B alleles.

PubMed

Lazaro, A M; Xiao, Y; Cao, K; Masaberg, C; Nichol, L; Ng, J; Hurley, C K; Posch, P E

2008-05-01

Twenty-eight novel human leukocyte antigen-B alleles are described: one B*07 (*0745), two B*08 (*0826 and *0831), one B*27 (*2731), four B*35 (*350106, *350402, *3566, and *3568), two B*37 (*370102 and *3711), two B*38 (*380102 and *3813), two B*39 (*3935 and *3939), one B*41 (*4108), one B*42 (*4209), two B*44 (*4444 and *4448), two B*48 (*480302 and *4815), one B*51 (*5140), one B*55 (*5523), one B*56 (*5617), two B*57 (*570103 and *5710), and three B*15 (*9505, *9510, and *9519). Sixteen of the variants are single-nucleotide substitutions from their most homologous allele, of which 10 result in amino acid changes (B*0745, *0831, *3813, *3935, *3939, *4815, *9505, *9509, *9510, and *9519) and 6 are silent substitutions. The remaining alleles (B*0826, *2731, *3566, *3568, *3711, *4108, *4209, *4444, *4448, *5140, *5523, *5617, and *5710) differ from their most similar alleles by two to seven nucleotides substitutions, altering from one to five amino acids.

Allelic differences within and among sister spores of the arbuscular mycorrhizal fungus Glomus etunicatum suggest segregation at sporulation.

PubMed

Boon, Eva; Zimmerman, Erin; St-Arnaud, Marc; Hijri, Mohamed

2013-01-01

Arbuscular mycorrhizal fungi (AMF) are root-inhabiting fungi that form mutualistic symbioses with their host plants. AMF are made up of coenocytic networks of hyphae through which nuclei and organelles can freely migrate. In this study, we investigated the possibility of a genetic bottleneck and segregation of allelic variation at sporulation for a low-copy Polymerase1-like gene, PLS. Specifically, our objectives were (1) to estimate what allelic diversity is passed on to a single spore (2) to determine whether this diversity is less than the total amount of variation found in all spores (3) to investigate whether there is any differential segregation of allelic variation. We inoculated three tomato plants with a single spore of Glomus etunicatum each and after six months sampled between two and three daughter spores per tomato plant. Pyrosequencing PLS amplicons in eight spores revealed high levels of allelic diversity; between 43 and 152 alleles per spore. We corroborated the spore pyrosequencing results with Sanger- and pyrosequenced allele distributions from the original parent isolate. Both sequencing methods retrieved the most abundant alleles from the offspring spore allele distributions. Our results indicate that individual spores contain only a subset of the total allelic variation from the pooled spores and parent isolate. Patterns of allele diversity between spores suggest the possibility for segregation of PLS alleles among spores. We conclude that a genetic bottleneck could potentially occur during sporulation in AMF, with resulting differences in genetic variation among sister spores. We suggest that the effects of this bottleneck may be countered by anastomosis (hyphal fusion) between related hyphae.

Development of genetic diversity, differentiation and structure over 500 years in four ponderosa pine populations.

PubMed

Lesser, M R; Parchman, T L; Jackson, S T

2013-05-01

Population history plays an important role in shaping contemporary levels of genetic variation and geographic structure. This is especially true in small, isolated range-margin populations, where effects of inbreeding, genetic drift and gene flow may be more pronounced than in large continuous populations. Effects of landscape fragmentation and isolation distance may have implications for persistence of range-margin populations if they are demographic sinks. We studied four small, disjunct populations of ponderosa pine over a 500-year period. We coupled demographic data obtained through dendroecological methods with microsatellite data to discern how and when contemporary levels of allelic diversity, among and within-population levels of differentiation, and geographic structure, arose. Alleles accumulated rapidly following initial colonization, demonstrating proportionally high levels of gene flow into the populations. At population sizes of approximately 100 individuals, allele accumulation saturated. Levels of genetic differentiation among populations (F(ST) and Jost's D(est)) and diversity within populations (F(IS)) remained stable through time. There was no evidence of geographic genetic structure at any time in the populations' history. Proportionally, high gene flow in the early stages of population growth resulted in rapid accumulation of alleles and quickly created relatively homogenous genetic patterns among populations. Our study demonstrates that contemporary levels of genetic diversity were formed quickly and early in population development. How contemporary genetic diversity accumulates over time is a key facet of understanding population growth and development. This is especially relevant given the extent and speed at which species ranges are predicted to shift in the coming century. © 2013 Blackwell Publishing Ltd.

Allelic Differences within and among Sister Spores of the Arbuscular Mycorrhizal Fungus Glomus etunicatum Suggest Segregation at Sporulation

PubMed Central

St-Arnaud, Marc; Hijri, Mohamed

2013-01-01

Arbuscular mycorrhizal fungi (AMF) are root-inhabiting fungi that form mutualistic symbioses with their host plants. AMF are made up of coenocytic networks of hyphae through which nuclei and organelles can freely migrate. In this study, we investigated the possibility of a genetic bottleneck and segregation of allelic variation at sporulation for a low-copy Polymerase1-like gene, PLS. Specifically, our objectives were (1) to estimate what allelic diversity is passed on to a single spore (2) to determine whether this diversity is less than the total amount of variation found in all spores (3) to investigate whether there is any differential segregation of allelic variation. We inoculated three tomato plants with a single spore of Glomus etunicatum each and after six months sampled between two and three daughter spores per tomato plant. Pyrosequencing PLS amplicons in eight spores revealed high levels of allelic diversity; between 43 and 152 alleles per spore. We corroborated the spore pyrosequencing results with Sanger- and pyrosequenced allele distributions from the original parent isolate. Both sequencing methods retrieved the most abundant alleles from the offspring spore allele distributions. Our results indicate that individual spores contain only a subset of the total allelic variation from the pooled spores and parent isolate. Patterns of allele diversity between spores suggest the possibility for segregation of PLS alleles among spores. We conclude that a genetic bottleneck could potentially occur during sporulation in AMF, with resulting differences in genetic variation among sister spores. We suggest that the effects of this bottleneck may be countered by anastomosis (hyphal fusion) between related hyphae. PMID:24386173

Microsatellite-based genetic diversity patterns in disjunct populations of a rare orchid.

PubMed

Pandey, Madhav; Richards, Matt; Sharma, Jyotsna

2015-12-01

We investigated the patterns of genetic diversity and structure in seven disjunct populations of a rare North American orchid, Cypripedium kentuckiense by including populations that represented the periphery and the center of the its range. Eight nuclear and two chloroplast microsatellites were used. Genetic diversity was low across the sampled populations of C. kentuckiense based on both nuclear (average An = 4.0, Ho = 0.436, He = 0.448) and cpDNA microsatellites (average An = 1.57, Nh = 1.57 and H = 0.133). The number of private alleles ranged from one to four per population with a total of 17 private alleles detected at five nuclear microsatellites. One private allele at one cpDNA microsatellite was also observed. Although the absolute values for nuclear microsatellite based population differentiation were low (Fst = 0.075; ϕPT = 0.24), they were statistically significant. Pairwise Fst values ranged from 0.038 to 0.123 and each comparison was significant. We also detected isolation by distance with nDNA microsatellites based on the Mantel test (r(2) = 0.209, P = 0.05). STRUCTURE analysis and the neighbor joining trees grouped the populations similarly whereby the geographically proximal populations were genetically similar. Our data indicate that the species is genetically depauperate but the diversity is distributed more or less equally across its range. Population differentiation and isolation by distance were detectable, which indicates that genetic isolation is beginning to manifest itself across the range in this rare species.

Adapting populations in space: clonal interference and genetic diversity

NASA Astrophysics Data System (ADS)

Weissman, Daniel; Barton, Nick

Most species inhabit ranges much larger than the scales over which individuals interact. How does this spatial structure interact with adaptive evolution? We consider a simple model of a spatially-extended, adapting population and show that, while clonal interference severely limits the adaptation of purely asexual populations, even rare recombination is enough to allow adaptation at rates approaching those of well-mixed populations. We also find that the genetic hitchhiking produced by the adaptive alleles sweeping through the population has strange effects on the patterns of genetic diversity. In large spatial ranges, even low rates of adaptation cause all individuals in the population to rapidly trace their ancestry back to individuals living in a small region in the center of the range. The probability of fixation of an allele is thus strongly dependent on the allele's spatial location, with alleles from the center favored. Surprisingly, these effects are seen genome-wide (instead of being localized to the regions of the genome undergoing the sweeps). The spatial concentration of ancestry produces a power-law dependence of relatedness on distance, so that even individuals sampled far apart are likely to be fairly closely related, masking the underlying spatial structure.

Analysis of nucleotide diversity among alleles of the major bacterial blight resistance gene Xa27 in cultivars of rice (Oryza sativa) and its wild relatives.

PubMed

Bimolata, Waikhom; Kumar, Anirudh; Sundaram, Raman Meenakshi; Laha, Gouri Shankar; Qureshi, Insaf Ahmed; Reddy, Gajjala Ashok; Ghazi, Irfan Ahmad

2013-08-01

Xa27 is one of the important R-genes, effective against bacterial blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Using natural population of Oryza, we analyzed the sequence variation in the functionally important domains of Xa27 across the Oryza species. DNA sequences of Xa27 alleles from 27 rice accessions revealed higher nucleotide diversity among the reported R-genes of rice. Sequence polymorphism analysis revealed synonymous and non-synonymous mutations in addition to a number of InDels in non-coding regions of the gene. High sequence variation was observed in the promoter region including the 5'UTR with 'π' value 0.00916 and 'θ w ' = 0.01785. Comparative analysis of the identified Xa27 alleles with that of IRBB27 and IR24 indicated the operation of both positive selection (Ka/Ks > 1) and neutral selection (Ka/Ks ≈ 0). The genetic distances of alleles of the gene from Oryza nivara were nearer to IRBB27 as compared to IR24. We also found the presence of conserved and null UPT (upregulated by transcriptional activator) box in the isolated alleles. Considerable amino acid polymorphism was localized in the trans-membrane domain for which the functional significance is yet to be elucidated. However, the absence of functional UPT box in all the alleles except IRBB27 suggests the maintenance of single resistant allele throughout the natural population.

[Genetic diversity of microsatellite loci in captive Amur tigers].

PubMed

Zhang, Yu-Gaung; Li, Di-Qiang; Xiao, Qi-Ming; Rao, Li-Qun; Zhang, Xue-Wen

2004-09-01

The tiger is one of the most threatened wildlife species since the abundance and distribution of tiger have decreased dramatically in the last century. The wild Amur tiger (Panthera tigris altaica) only distributed in northeast China, the far east area of Russia and the north Korea and its size of wild population is about 450 in the world and 20 in China. Several hundred captive populations of Amur tigers are the main source to protect gene library of tiger and the source of recovering the wild populations. The Breeding Center for Felidae at Hengdaohezi and Haoerbin Tiger Park in Heilongjiang Province is the biggest captive breeding base in China. How to make clear the genetic pedigree and establish reasonable breeding system is the urgent issues. So we use the microsatellite DNA markers and non-invasive technology to research on the genetic diversity of captive Amur tiger in this study. Ten microsatellite loci (Fca005, Fca075, Fca094, Fca152, Fca161, Fca294, Pti002, Pti003, Pti007 and Pti010), highly variable nuclear markers, were studied their genetic diversity in 113 captive Amur tigers. The PCR amplified products of microsatellite loci were detected by non-denatured polyacrylamide gel electrophoresis. Allele numbers, allelic frequency, gene heterozygosity(H(e)), polymorphism information content(PIC) and effective number of allele(N(e)) were calculated. 41 alleles were found and their size were ranged from 110bp to 250bp in ten microsatellite loci, Fca152 had 6 alleles, Fca075, Fca094 and Fca294 had 5 alleles, Fca005 and Pti002 had 4 alleles and the others had 3 alleles in all tiger samples, respectively. The allelic frequencies were from 0.009 to 0.767; The He ranged from 0.385 to 0.707, and Fca294 and Pti010 locus had the highest and lowest value; the PIC were from 0.353 to 0.658, Fca294 and Pti010 locus had the highest and lowest value; and N(e) were from 1.626 to 3.409, Fca294 and Pti010 locus had the highest and lowest value, which showed the ten

Diploid male dynamics under different numbers of sexual alleles and male dispersal abilities.

PubMed

Faria, Luiz R R; Soares, Elaine Della Giustina; Carmo, Eduardo do; Oliveira, Paulo Murilo Castro de

2016-09-01

Insects in the order Hymenoptera (bees, wasps and ants) present an haplodiploid system of sexual determination in which fertilized eggs become females and unfertilized eggs males. Under single locus complementary sex-determination (sl-CSD) system, the sex of a specimen depends on the alleles at a single locus: when diploid, an individual will be a female if heterozygous and male if homozygous. Significant diploid male (DM) production may drive a population to an extinction scenario called "diploid male vortex". We aimed at studying the dynamics of populations of a sl-CSD organism under several combinations of two parameters: male flight abilities and number of sexual alleles. In these simulations, we evaluated the frequency of DM and a genetic diversity measure over 10,000 generations. The number of sexual alleles varied from 10 to 100 and, at each generation, a male offspring might fly to another random site within a varying radius R. Two main results emerge from our simulations: (i) the number of DM depends more on male flight radius than on the number of alleles; (ii) in large geographic regions, the effect of males flight radius on the allelic diversity turns out much less pronounced than in small regions. In other words, small regions where inbreeding normally appears recover genetic diversity due to large flight radii. These results may be particularly relevant when considering the population dynamics of species with increasingly limited dispersal ability (e.g., forest-dependent species of euglossine bees in fragmented landscapes).

An extensive allelic series of Drosophila kae1 mutants reveals diverse and tissue-specific requirements for t6A biogenesis

PubMed Central

Lin, Ching-Jung; Smibert, Peter; Zhao, Xiaoyu; Hu, Jennifer F.; Ramroop, Johnny; Kellner, Stefanie M.; Benton, Matthew A.; Govind, Shubha; Dedon, Peter C.; Sternglanz, Rolf; Lai, Eric C.

2015-01-01

N6-threonylcarbamoyl-adenosine (t6A) is one of the few RNA modifications that is universally present in life. This modification occurs at high frequency at position 37 of most tRNAs that decode ANN codons, and stabilizes cognate anticodon–codon interactions. Nearly all genetic studies of the t6A pathway have focused on single-celled organisms. In this study, we report the isolation of an extensive allelic series in the Drosophila ortholog of the core t6A biosynthesis factor Kae1. kae1 hemizygous larvae exhibit decreases in t6A that correlate with allele strength; however, we still detect substantial t6A-modified tRNAs even during the extended larval phase of null alleles. Nevertheless, complementation of Drosophila Kae1 and other t6A factors in corresponding yeast null mutants demonstrates that these metazoan genes execute t6A synthesis. Turning to the biological consequences of t6A loss, we characterize prominent kae1 melanotic masses and show that they are associated with lymph gland overgrowth and ectopic generation of lamellocytes. On the other hand, kae1 mutants exhibit other phenotypes that reflect insufficient tissue growth. Interestingly, whole-tissue and clonal analyses show that strongly mitotic tissues such as imaginal discs are exquisitely sensitive to loss of kae1, whereas nonproliferating tissues are less affected. Indeed, despite overt requirements of t6A for growth of many tissues, certain strong kae1 alleles achieve and sustain enlarged body size during their extended larval phase. Our studies highlight tissue-specific requirements of the t6A pathway in a metazoan context and provide insights into the diverse biological roles of this fundamental RNA modification during animal development and disease. PMID:26516084

Genetic diversity of Bromeliaceae species from the Atlantic Forest.

PubMed

Sheu, Y; Cunha-Machado, A S; Gontijo, A B P L; Favoreto, F C; Soares, T B C; Miranda, F D

2017-04-20

The Bromeliaceae family includes a range of species used for many purposes, including ornamental use and use as food, medicine, feed, and fiber. The state of Espírito Santo, Brazil is a center of diversity for this family in the Atlantic Forest. We evaluated the genetic diversity of five populations of the Bromeliaceae family, including specimens of the genera Aechmea, Billbergia (subfamily Bromelioideae), and Pitcairnia (subfamily Pitcairnioidea), all found in the Atlantic Forest and distributed in the state of Espírito Santo. The number of alleles per locus in populations ranged from two to six and the fixation index (F), estimated for some simple sequence repeats in bromeliad populations, was less than zero in all populations. All markers in the Pitcairnia flammea population were in Hardy-Weinberg equilibrium (P < 0.05). Moreover, significant deviations from Hardy-Weinberg equilibrium were observed at some loci in populations of the five bromeliad species. In most cases, this can be attributed to the presence of inbreeding or the Wahlund effect. The genetic diversity indices of five species showed greater allelic richness in P. flammea (3.55). Therefore, we provide useful information for the characterization of genetic diversity in natural populations of Aechmea ramosa, Aechmea nudicaulis, Billbergia horrid, Billbergia euphemia, and P. flammea in Atlantic Forest remnants in the south of Espírito Santo state.

High-precision genetic mapping of behavioral traits in the diversity outbred mouse population

PubMed Central

Logan, R W; Robledo, R F; Recla, J M; Philip, V M; Bubier, J A; Jay, J J; Harwood, C; Wilcox, T; Gatti, D M; Bult, C J; Churchill, G A; Chesler, E J

2013-01-01

Historically our ability to identify genetic variants underlying complex behavioral traits in mice has been limited by low mapping resolution of conventional mouse crosses. The newly developed Diversity Outbred (DO) population promises to deliver improved resolution that will circumvent costly fine-mapping studies. The DO is derived from the same founder strains as the Collaborative Cross (CC), including three wild-derived strains. Thus the DO provides more allelic diversity and greater potential for discovery compared to crosses involving standard mouse strains. We have characterized 283 male and female DO mice using open-field, light–dark box, tail-suspension and visual-cliff avoidance tests to generate 38 behavioral measures. We identified several quantitative trait loci (QTL) for these traits with support intervals ranging from 1 to 3 Mb in size. These intervals contain relatively few genes (ranging from 5 to 96). For a majority of QTL, using the founder allelic effects together with whole genome sequence data, we could further narrow the positional candidates. Several QTL replicate previously published loci. Novel loci were also identified for anxiety- and activity-related traits. Half of the QTLs are associated with wild-derived alleles, confirming the value to behavioral genetics of added genetic diversity in the DO. In the presence of wild-alleles we sometimes observe behaviors that are qualitatively different from the expected response. Our results demonstrate that high-precision mapping of behavioral traits can be achieved with moderate numbers of DO animals, representing a significant advance in our ability to leverage the mouse as a tool for behavioral genetics PMID:23433259

Hidden MHC genetic diversity in the Iberian ibex (Capra pyrenaica).

PubMed

Angelone, Samer; Jowers, Michael J; Molinar Min, Anna Rita; Fandos, Paulino; Prieto, Paloma; Pasquetti, Mario; Cano-Manuel, Francisco Javier; Mentaberre, Gregorio; Olvera, Jorge Ramón López; Ráez-Bravo, Arián; Espinosa, José; Pérez, Jesús M; Soriguer, Ramón C; Rossi, Luca; Granados, José Enrique

2018-05-08

Defining hidden genetic diversity within species is of great significance when attempting to maintain the evolutionary potential of natural populations and conduct appropriate management. Our hypothesis is that isolated (and eventually small) wild animal populations hide unexpected genetic diversity due to their maintenance of ancient polymorphisms or introgressions. We tested this hypothesis using the Iberian ibex (Capra pyrenaica) as an example. Previous studies based on large sample sizes taken from its principal populations have revealed that the Iberian ibex has a remarkably small MHC DRB1 diversity (only six remnant alleles) as a result of recent population bottlenecks and a marked demographic decline that has led to the extinction of two recognized subspecies. Extending on the geographic range to include non-studied isolated Iberian ibex populations, we sequenced a new MHC DRB1 in what seemed three small isolated populations in Southern Spain (n = 132). The findings indicate a higher genetic diversity than previously reported in this important gene. The newly discovered allele, MHC DRB1*7, is identical to one reported in the domestic goat C. aegagrus hircus. Whether or not this is the result of ancient polymorphisms maintained by balancing selection or, alternatively, introgressions from domestic goats through hybridization needs to be clarified in future studies. However, hybridization between Iberian ibex and domestic goats has been reported in Spain and the fact that the newly discovered allele is only present in one of the small isolated populations and not in the others suggests introgression. The new discovered allele is not expected to increase fitness in C. pyrenaica since it generates the same protein as the existing MHC DRB1*6. Analysis of a microsatellite locus (OLADRB1) near the new MHC DRB1*7 gene reveals a linkage disequilibrium between these two loci. The allele OLADRB1, 187 bp in length, was unambiguously linked to the MHC DRB1*7 allele

SSR allelic variation in almond (Prunus dulcis Mill.).

PubMed

Xie, Hua; Sui, Yi; Chang, Feng-Qi; Xu, Yong; Ma, Rong-Cai

2006-01-01

Sixteen SSR markers including eight EST-SSR and eight genomic SSRs were used for genetic diversity analysis of 23 Chinese and 15 international almond cultivars. EST- and genomic SSR markers previously reported in species of Prunus, mainly peach, proved to be useful for almond genetic analysis. DNA sequences of 117 alleles of six of the 16 SSR loci were analysed to reveal sequence variation among the 38 almond accessions. For the four SSR loci with AG/CT repeats, no insertions or deletions were observed in the flanking regions of the 98 alleles sequenced. Allelic size variation of these loci resulted exclusively from differences in the structures of repeat motifs, which involved interruptions or occurrences of new motif repeats in addition to varying number of AG/CT repeats. Some alleles had a high number of uninterrupted repeat motifs, indicating that SSR mutational patterns differ among alleles at a given SSR locus within the almond species. Allelic homoplasy was observed in the SSR loci because of base substitutions, interruptions or compound repeat motifs. Substitutions in the repeat regions were found at two SSR loci, suggesting that point mutations operate on SSRs and hinder the further SSR expansion by introducing repeat interruptions to stabilize SSR loci. Furthermore, it was shown that some potential point mutations in the flanking regions are linked with new SSR repeat motif variation in almond and peach.

Geographically Distinct and Domain-Specific Sequence Variations in the Alleles of Rice Blast Resistance Gene Pib

PubMed Central

Vasudevan, Kumar; Vera Cruz, Casiana M.; Gruissem, Wilhelm; Bhullar, Navreet K.

2016-01-01

Rice blast is caused by Magnaporthe oryzae, which is the most destructive fungal pathogen affecting rice growing regions worldwide. The rice blast resistance gene Pib confers broad-spectrum resistance against Southeast Asian M. oryzae races. We investigated the allelic diversity of Pib in rice germplasm originating from 12 major rice growing countries. Twenty-five new Pib alleles were identified that have unique single nucleotide polymorphisms (SNPs), insertions and/or deletions, in addition to the polymorphic nucleotides that are shared between the different alleles. These partially or completely shared polymorphic nucleotides indicate frequent sequence exchange events between the Pib alleles. In some of the new Pib alleles, nucleotide diversity is high in the LRR domain, whereas, in others it is distributed among the NB-ARC and LRR domains. Most of the polymorphic amino acids in LRR and NB-ARC2 domains are predicted as solvent-exposed. Several of the alleles and the unique SNPs are country specific, suggesting a diversifying selection of alleles in various geographical locations in response to the locally prevalent M. oryzae population. Together, the new Pib alleles are an important genetic resource for rice blast resistance breeding programs and provide new information on rice-M. oryzae interactions at the molecular level. PMID:27446145

Molecular diversity of HLA-Cw alleles in the Maratha community of Mumbai, Maharashtra, western India.

PubMed

Shankarkumar, U; Ghosh, K; Mohanty, D

2005-08-01

Recent advances suggest a significant role for the HLA-C locus as a target of alloreactions after bone marrow transplantation. The biological importance of products of the HLA-C locus, both as transplant antigens and as ligands for natural killer (NK) cells, is well established. A total of 10 different serologically defined HLA-Cw antigen specificities (Cw1-Cw10) are encoded by the C locus; however, there are now 151 different alleles that can be identified by molecular methods. Serological definition of Cw alleles therefore includes 20-50% blanks, which cannot be detected by the available antisera. We used the molecular method of polymerase chain reaction (PCR)-based sequence-specific amplification and probe hybridization to define Cw alleles in 91 individuals from the Maratha community, and compared the data with data for 92 serologically typed Maratha individuals from India. We identified Cw*12, Cw*14, Cw*15, Cw*16 and Cw*18, along with the serologically identified Cw*01, Cw*02, Cw*03, Cw*04, Cw*06 and Cw*07 alleles. The HLA-Cw blank allele frequency in the Maratha was reduced from 0.5706 to 0.00. Furthermore, by using a molecular technique, it was possible to identify novel allele subtypes, such as Cw*0104, Cw*0203 and Cw*0707, and a high frequency of Cw* 1801 in the Maratha community compared with other Indian and world populations. Our results will have clinical implications in related and unrelated HLA-matched bone marrow transplantation in India.

A hypervariable STR polymorphism in the CFI gene: southern origin of East Asian-specific group H alleles.

PubMed

Yuasa, Isao; Jin, Feng; Harihara, Shinji; Matsusue, Aya; Fujihara, Junko; Takeshita, Haruo; Akane, Atsushi; Umetsu, Kazuo; Saitou, Naruya; Chattopadhyay, Prasanta K

2013-09-01

Previous studies of four populations revealed that a hypervariable short tandem repeat (iSTR) in intron 7 of the human complement factor I (CFI) gene on chromosome 4q was unique, with 17 possible East Asian-specific group H alleles observed at relatively high frequencies. To develop a deeper anthropological and forensic understanding of iSTR, 1161 additional individuals from 11 Asian populations were investigated. Group H alleles of iSTR and c.1217A allele of a SNP in exon 11 of the CFI gene were associated with each other and were almost entirely confined to East Asian populations. Han Chinese in Changsha, southern China, showed the highest frequency for East Asian-specific group H alleles (0.201) among 15 populations. Group H alleles were observed to decrease gradually from south to north in 11 East Asian populations. This expansion of group H alleles provides evidence that southern China and Southeast Asia are a hotspot of Asian diversity and a genetic reservoir of Asians after they entered East Asia. The expected heterozygosity values of iSTR ranged from 0.927 in Thais to 0.874 in Oroqens, higher than those of an STR in the fibrinogen alpha chain (FGA) gene on chromosome 4q. Thus, iSTR is a useful marker for anthropological and forensic genetics. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Assessment of allelic diversity in intron-containing Mal d 1 genes and their association to apple allergenicity

PubMed Central

Gao, Zhongshan; Weg, Eric W van de; Matos, Catarina I; Arens, Paul; Bolhaar, Suzanne THP; Knulst, Andre C; Li, Yinghui; Hoffmann-Sommergruber, Karin; Gilissen, Luud JWJ

2008-01-01

Background Mal d 1 is a major apple allergen causing food allergic symptoms of the oral allergy syndrome (OAS) in birch-pollen sensitised patients. The Mal d 1 gene family is known to have at least 7 intron-containing and 11 intronless members that have been mapped in clusters on three linkage groups. In this study, the allelic diversity of the seven intron-containing Mal d 1 genes was assessed among a set of apple cultivars by sequencing or indirectly through pedigree genotyping. Protein variant constitutions were subsequently compared with Skin Prick Test (SPT) responses to study the association of deduced protein variants with allergenicity in a set of 14 cultivars. Results From the seven intron-containing Mal d 1 genes investigated, Mal d 1.01 and Mal d 1.02 were highly conserved, as nine out of ten cultivars coded for the same protein variant, while only one cultivar coded for a second variant. Mal d 1.04, Mal d 1.05 and Mal d 1.06 A, B and C were more variable, coding for three to six different protein variants. Comparison of Mal d 1 allelic composition between the high-allergenic cultivar Golden Delicious and the low-allergenic cultivars Santana and Priscilla, which are linked in pedigree, showed an association between the protein variants coded by the Mal d 1.04 and -1.06A genes (both located on linkage group 16) with allergenicity. This association was confirmed in 10 other cultivars. In addition, Mal d 1.06A allele dosage effects associated with the degree of allergenicity based on prick to prick testing. Conversely, no associations were observed for the protein variants coded by the Mal d 1.01 (on linkage group 13), -1.02, -1.06B, -1.06C genes (all on linkage group 16), nor by the Mal d 1.05 gene (on linkage group 6). Conclusion Protein variant compositions of Mal d 1.04 and -1.06A and, in case of Mal d 1.06A, allele doses are associated with the differences in allergenicity among fourteen apple cultivars. This information indicates the involvement of

Robust Identification of Local Adaptation from Allele Frequencies

PubMed Central

Günther, Torsten; Coop, Graham

2013-01-01

Comparing allele frequencies among populations that differ in environment has long been a tool for detecting loci involved in local adaptation. However, such analyses are complicated by an imperfect knowledge of population allele frequencies and neutral correlations of allele frequencies among populations due to shared population history and gene flow. Here we develop a set of methods to robustly test for unusual allele frequency patterns and correlations between environmental variables and allele frequencies while accounting for these complications based on a Bayesian model previously implemented in the software Bayenv. Using this model, we calculate a set of “standardized allele frequencies” that allows investigators to apply tests of their choice to multiple populations while accounting for sampling and covariance due to population history. We illustrate this first by showing that these standardized frequencies can be used to detect nonparametric correlations with environmental variables; these correlations are also less prone to spurious results due to outlier populations. We then demonstrate how these standardized allele frequencies can be used to construct a test to detect SNPs that deviate strongly from neutral population structure. This test is conceptually related to FST and is shown to be more powerful, as we account for population history. We also extend the model to next-generation sequencing of population pools—a cost-efficient way to estimate population allele frequencies, but one that introduces an additional level of sampling noise. The utility of these methods is demonstrated in simulations and by reanalyzing human SNP data from the Human Genome Diversity Panel populations and pooled next-generation sequencing data from Atlantic herring. An implementation of our method is available from http://gcbias.org. PMID:23821598

The Equilibrium Allele Frequency Distribution for a Population with Reproductive Skew

PubMed Central

Der, Ricky; Plotkin, Joshua B.

2014-01-01

We study the population genetics of two neutral alleles under reversible mutation in a model that features a skewed offspring distribution, called the Λ-Fleming–Viot process. We describe the shape of the equilibrium allele frequency distribution as a function of the model parameters. We show that the mutation rates can be uniquely identified from this equilibrium distribution, but the form of the offspring distribution cannot itself always be so identified. We introduce an estimator for the mutation rate that is consistent, independent of the form of reproductive skew. We also introduce a two-allele infinite-sites version of the Λ-Fleming–Viot process, and we use it to study how reproductive skew influences standing genetic diversity in a population. We derive asymptotic formulas for the expected number of segregating sites as a function of sample size and offspring distribution. We find that the Wright–Fisher model minimizes the equilibrium genetic diversity, for a given mutation rate and variance effective population size, compared to all other Λ-processes. PMID:24473932

Role of the B Allele of Influenza A Virus Segment 8 in Setting Mammalian Host Range and Pathogenicity

PubMed Central

Turnbull, Matthew L.; Wise, Helen M.; Nicol, Marlynne Q.; Smith, Nikki; Dunfee, Rebecca L.; Beard, Philippa M.; Jagger, Brett W.; Ligertwood, Yvonne; Hardisty, Gareth R.; Xiao, Haixia; Benton, Donald J.; Coburn, Alice M.; Paulo, Joao A.; Gygi, Steven P.; McCauley, John W.; Taubenberger, Jeffery K.; Lycett, Samantha J.; Weekes, Michael P.; Dutia, Bernadette M.

2016-01-01

ABSTRACT Two alleles of segment 8 (NS) circulate in nonchiropteran influenza A viruses. The A allele is found in avian and mammalian viruses, but the B allele is viewed as being almost exclusively found in avian viruses. This might reflect the fact that one or both of its encoded proteins (NS1 and NEP) are maladapted for replication in mammalian hosts. To test this, a number of clade A and B avian virus-derived NS segments were introduced into human H1N1 and H3N2 viruses. In no case was the peak virus titer substantially reduced following infection of various mammalian cell types. Exemplar reassortant viruses also replicated to similar titers in mice, although mice infected with viruses with the avian virus-derived segment 8s had reduced weight loss compared to that achieved in mice infected with the A/Puerto Rico/8/1934 (H1N1) parent. In vitro, the viruses coped similarly with type I interferons. Temporal proteomics analysis of cellular responses to infection showed that the avian virus-derived NS segments provoked lower levels of expression of interferon-stimulated genes in cells than wild type-derived NS segments. Thus, neither the A nor the B allele of avian virus-derived NS segments necessarily attenuates virus replication in a mammalian host, although the alleles can attenuate disease. Phylogenetic analyses identified 32 independent incursions of an avian virus-derived A allele into mammals, whereas 6 introductions of a B allele were identified. However, A-allele isolates from birds outnumbered B-allele isolates, and the relative rates of Aves-to-Mammalia transmission were not significantly different. We conclude that while the introduction of an avian virus segment 8 into mammals is a relatively rare event, the dogma of the B allele being especially restricted is misleading, with implications in the assessment of the pandemic potential of avian influenza viruses. IMPORTANCE Influenza A virus (IAV) can adapt to poultry and mammalian species, inflicting a

Role of the B Allele of Influenza A Virus Segment 8 in Setting Mammalian Host Range and Pathogenicity.

PubMed

Turnbull, Matthew L; Wise, Helen M; Nicol, Marlynne Q; Smith, Nikki; Dunfee, Rebecca L; Beard, Philippa M; Jagger, Brett W; Ligertwood, Yvonne; Hardisty, Gareth R; Xiao, Haixia; Benton, Donald J; Coburn, Alice M; Paulo, Joao A; Gygi, Steven P; McCauley, John W; Taubenberger, Jeffery K; Lycett, Samantha J; Weekes, Michael P; Dutia, Bernadette M; Digard, Paul

2016-10-15

Two alleles of segment 8 (NS) circulate in nonchiropteran influenza A viruses. The A allele is found in avian and mammalian viruses, but the B allele is viewed as being almost exclusively found in avian viruses. This might reflect the fact that one or both of its encoded proteins (NS1 and NEP) are maladapted for replication in mammalian hosts. To test this, a number of clade A and B avian virus-derived NS segments were introduced into human H1N1 and H3N2 viruses. In no case was the peak virus titer substantially reduced following infection of various mammalian cell types. Exemplar reassortant viruses also replicated to similar titers in mice, although mice infected with viruses with the avian virus-derived segment 8s had reduced weight loss compared to that achieved in mice infected with the A/Puerto Rico/8/1934 (H1N1) parent. In vitro, the viruses coped similarly with type I interferons. Temporal proteomics analysis of cellular responses to infection showed that the avian virus-derived NS segments provoked lower levels of expression of interferon-stimulated genes in cells than wild type-derived NS segments. Thus, neither the A nor the B allele of avian virus-derived NS segments necessarily attenuates virus replication in a mammalian host, although the alleles can attenuate disease. Phylogenetic analyses identified 32 independent incursions of an avian virus-derived A allele into mammals, whereas 6 introductions of a B allele were identified. However, A-allele isolates from birds outnumbered B-allele isolates, and the relative rates of Aves-to-Mammalia transmission were not significantly different. We conclude that while the introduction of an avian virus segment 8 into mammals is a relatively rare event, the dogma of the B allele being especially restricted is misleading, with implications in the assessment of the pandemic potential of avian influenza viruses. Influenza A virus (IAV) can adapt to poultry and mammalian species, inflicting a great socioeconomic

Development of SSR Markers and Genetic Diversity in White Birch (Betula platyphylla)

PubMed Central

Hao, Wei; Wang, Shengji; Liu, Huajing; Zhou, Boru; Wang, Xinwang; Jiang, Tingbo

2015-01-01

In order to study genetic diversity of white birch (Betula platyphylla), 544 primer pairs were designed based on the genome-wide Solexa sequences. Among them, 215 primer pairs showed polymorphism between five genotypes and 111 primer pairs that presented clear visible bands in genotyping 41 white birch plants that were collected from 6 different geographical regions. A total of 717 alleles were obtained at 111 loci with a range of 2 to 12 alleles per locus. The results of statistic analysis showed that polymorphic frequency of the alleles ranged from 17% to 100% with a mean of 55.85%; polymorphism information content (PIC) of the loci was from 0.09 to 0.58 with a mean of 0.30; and gene diversity between the tested genotypes was from 0.01 to 0.66 with a mean of 0.36. The results also indicated that major allele frequency ranged from 0.39 to 1.00 with an mean of 0.75; expected heterozygosity from 0.22 to 0.54 with a mean of 0.46; observed heterozygosity from 0.02 to 0.95 with a mean of 0.26; Nei's index from 0.21 to 0.54 with a mean of 0.46; and Shannon's Information from 0.26 to 0.87 with a mean of 0.66. The 41 white birch genotypes at the 111 selected SSR loci showed low to moderate similarity (0.025-0.610), indicating complicated genetic diversity among the white birch collections. The UPGMA-based clustering analysis of the allelic constitution of 41 white birch genotypes at 111 SSR loci suggested that the six different geographical regions can be further separated into four clusters at a similarity coefficient of 0.22. Genotypes from Huanren and Liangshui provenances were grouped into Cluster I, genotypes from Xiaobeihu and Qingyuan provenances into Cluster II, genotypes from Finland provenance into Cluster III, and genotypes from Maoershan into Cluster IV. The information provided in this study could help for genetic improvement and germplasm conservation, evaluation and utilization in white birch tree breeding program. PMID:25923698

Identification of novel alleles of the rice blast resistance gene Pi54

NASA Astrophysics Data System (ADS)

Vasudevan, Kumar; Gruissem, Wilhelm; Bhullar, Navreet K.

2015-10-01

Rice blast is one of the most devastating rice diseases and continuous resistance breeding is required to control the disease. The rice blast resistance gene Pi54 initially identified in an Indian cultivar confers broad-spectrum resistance in India. We explored the allelic diversity of the Pi54 gene among 885 Indian rice genotypes that were found resistant in our screening against field mixture of naturally existing M. oryzae strains as well as against five unique strains. These genotypes are also annotated as rice blast resistant in the International Rice Genebank database. Sequence-based allele mining was used to amplify and clone the Pi54 allelic variants. Nine new alleles of Pi54 were identified based on the nucleotide sequence comparison to the Pi54 reference sequence as well as to already known Pi54 alleles. DNA sequence analysis of the newly identified Pi54 alleles revealed several single polymorphic sites, three double deletions and an eight base pair deletion. A SNP-rich region was found between a tyrosine kinase phosphorylation site and the nucleotide binding site (NBS) domain. Together, the newly identified Pi54 alleles expand the allelic series and are candidates for rice blast resistance breeding programs.

Allele Surfing Promotes Microbial Adaptation from Standing Variation

PubMed Central

Gralka, Matti; Stiewe, Fabian; Farrell, Fred; Möbius, Wolfram; Waclaw, Bartek; Hallatschek, Oskar

2016-01-01

The coupling of ecology and evolution during range expansions enables mutations to establish at expanding range margins and reach high frequencies. This phenomenon, called allele surfing, is thought to have caused revolutions in the gene pool of many species, most evidently in microbial communities. It has remained unclear, however, under which conditions allele surfing promotes or hinders adaptation. Here, using microbial experiments and simulations, we show that, starting with standing adaptive variation, range expansions generate a larger increase in mean fitness than spatially uniform population expansions. The adaptation gain results from ‘soft’ selective sweeps emerging from surfing beneficial mutations. The rate of these surfing events is shown to sensitively depend on the strength of genetic drift, which varies among strains and environmental conditions. More generally, allele surfing promotes the rate of adaptation per biomass produced, which could help developing biofilms and other resource-limited populations to cope with environmental challenges. PMID:27307400

MICA diversity and linkage disequilibrium with HLA-B alleles in renal-transplant candidates in southern Brazil.

PubMed

Yamakawa, Roger Haruki; Saito, Patrícia Keiko; Gelmini, Geórgia Fernanda; da Silva, José Samuel; Bicalho, Maria da Graça; Borelli, Sueli Donizete

2017-01-01

The major histocompatibility complex (MHC) class I chain-related gene A (MICA) is located centromerically to the human leukocyte antigen (HLA)-B. The short distance between these loci in the MHC indicates the presence of linkage disequilibrium (LD). Similarly to the HLA, the MICA is highly polymorphic, and this polymorphism has not been well documented in different populations. In this study, we estimated the allelic frequencies of MICA and the linkage disequilibrium with HLA-B alleles in 346 renal-transplant candidates in southern Brazil. MICA and HLA were typed using the polymerase chain reaction-sequence-specific primer method (PCR-SSO), combined with the Luminex technology. A total of 19 MICA allele groups were identified. The most frequent allele groups were MICA*008 (21.6%), MICA*002 (17.0%) and MICA*004 (14.8%). The most common haplotypes were MICA*009-B*51 (7.8%), MICA*004-B*44 (6.06%) and MICA*002-B*35 (5.63%). As expected from the proximity of the MICA and HLA-B loci, most haplotypes showed strong LD. Renal patients and healthy subjects in the same region of Brazil showed statistically significant differences in their MICA polymorphisms. The MICA*027 allele group was more frequent in renal patients (Pc = 0.018, OR: 3.421, 95% CI: 1.516-7.722), while the MICA*019 allele group was more frequent in healthy subjects (Pc = 0.001, OR: 0.027, 95% CI: 0.002-0.469). This study provided information on the distribution of MICA polymorphisms and linkage disequilibrium with HLA-B alleles in Brazilian renal-transplant candidates. This information should help to determine the mechanisms of susceptibility to different diseases in patients with chronic kidney disease, and to elucidate the mechanisms involved in allograft rejection associated with MICA polymorphisms in a Brazilian population.

Analysis of genetic diversity and differentiation of seven stocks of Litopenaeus vannamei using microsatellite markers

NASA Astrophysics Data System (ADS)

Zhang, Kai; Wang, Weiji; Li, Weiya; Zhang, Quanqi; Kong, Jie

2014-08-01

Seven microsatellite markers were used to evaluate the genetic diversity and differentiation of seven stocks of Litopenaeus vannamei, which were introduced from Central and South America to China. All seven microsatellite loci were polymorphic, with polymorphism information content ( PIC) values ranging from 0.593 to 0.952. Totally 92 alleles were identified, and the number of alleles ( Na) and effective alleles ( Ne) varied between 4 and 21 and 2.7 and 14.6, respectively. Observed heterozygosity ( H o) values were lower than the expected heterozygosity ( H e) values (0.526-0.754), which indicated that the seven stocks possessed a rich genetic diversity. Thirty-seven tests were detected for reasonable significant deviation from Hardy-Weinberg equilibrium. F is values were positive at five loci, suggesting that there was a relatively high degree of inbreeding within stocks. Pairwise F st values ranged from 0.0225 to 0.151, and most of the stock pairs were moderately differentiated. Genetic distance and cluster analysis using UPGMA revealed a close genetic relationship of L. vannamei between Pop2 and Pop3. AMOVA indicated that the genetic variation among stocks (11.3%) was much lower than that within stocks (88.7%). Although the seven stocks had a certain degree of genetic differentiation and a rich genetic diversity, there is an increasing risk of decreased performance due to inbreeding in subsequent generations.

Multimer Formation Explains Allelic Suppression of PRDM9 Recombination Hotspots.

PubMed

Baker, Christopher L; Petkova, Pavlina; Walker, Michael; Flachs, Petr; Mihola, Ondrej; Trachtulec, Zdenek; Petkov, Petko M; Paigen, Kenneth

2015-09-01

Genetic recombination during meiosis functions to increase genetic diversity, promotes elimination of deleterious alleles, and helps assure proper segregation of chromatids. Mammalian recombination events are concentrated at specialized sites, termed hotspots, whose locations are determined by PRDM9, a zinc finger DNA-binding histone methyltransferase. Prdm9 is highly polymorphic with most alleles activating their own set of hotspots. In populations exhibiting high frequencies of heterozygosity, questions remain about the influences different alleles have in heterozygous individuals where the two variant forms of PRDM9 typically do not activate equivalent populations of hotspots. We now find that, in addition to activating its own hotspots, the presence of one Prdm9 allele can modify the activity of hotspots activated by the other allele. PRDM9 function is also dosage sensitive; Prdm9+/- heterozygous null mice have reduced numbers and less active hotspots and increased numbers of aberrant germ cells. In mice carrying two Prdm9 alleles, there is allelic competition; the stronger Prdm9 allele can partially or entirely suppress chromatin modification and recombination at hotspots of the weaker allele. In cell cultures, PRDM9 protein variants form functional heteromeric complexes which can bind hotspots sequences. When a heteromeric complex binds at a hotspot of one PRDM9 variant, the other PRDM9 variant, which would otherwise not bind, can still methylate hotspot nucleosomes. We propose that in heterozygous individuals the underlying molecular mechanism of allelic suppression results from formation of PRDM9 heteromers, where the DNA binding activity of one protein variant dominantly directs recombination initiation towards its own hotspots, effectively titrating down recombination by the other protein variant. In natural populations with many heterozygous individuals, allelic competition will influence the recombination landscape.

Multimer Formation Explains Allelic Suppression of PRDM9 Recombination Hotspots

PubMed Central

Baker, Christopher L.; Petkova, Pavlina; Walker, Michael; Flachs, Petr; Mihola, Ondrej; Trachtulec, Zdenek; Petkov, Petko M.; Paigen, Kenneth

2015-01-01

Genetic recombination during meiosis functions to increase genetic diversity, promotes elimination of deleterious alleles, and helps assure proper segregation of chromatids. Mammalian recombination events are concentrated at specialized sites, termed hotspots, whose locations are determined by PRDM9, a zinc finger DNA-binding histone methyltransferase. Prdm9 is highly polymorphic with most alleles activating their own set of hotspots. In populations exhibiting high frequencies of heterozygosity, questions remain about the influences different alleles have in heterozygous individuals where the two variant forms of PRDM9 typically do not activate equivalent populations of hotspots. We now find that, in addition to activating its own hotspots, the presence of one Prdm9 allele can modify the activity of hotspots activated by the other allele. PRDM9 function is also dosage sensitive; Prdm9 +/- heterozygous null mice have reduced numbers and less active hotspots and increased numbers of aberrant germ cells. In mice carrying two Prdm9 alleles, there is allelic competition; the stronger Prdm9 allele can partially or entirely suppress chromatin modification and recombination at hotspots of the weaker allele. In cell cultures, PRDM9 protein variants form functional heteromeric complexes which can bind hotspots sequences. When a heteromeric complex binds at a hotspot of one PRDM9 variant, the other PRDM9 variant, which would otherwise not bind, can still methylate hotspot nucleosomes. We propose that in heterozygous individuals the underlying molecular mechanism of allelic suppression results from formation of PRDM9 heteromers, where the DNA binding activity of one protein variant dominantly directs recombination initiation towards its own hotspots, effectively titrating down recombination by the other protein variant. In natural populations with many heterozygous individuals, allelic competition will influence the recombination landscape. PMID:26368021

KIR2DL2/2DL3-E35 alleles are functionally stronger than -Q35 alleles

NASA Astrophysics Data System (ADS)

Bari, Rafijul; Thapa, Rajoo; Bao, Ju; Li, Ying; Zheng, Jie; Leung, Wing

2016-03-01

KIR2DL2 and KIR2DL3 segregate as alleles of a single locus in the centromeric motif of the killer cell immunoglobulin-like receptor (KIR) gene family. Although KIR2DL2/L3 polymorphism is known to be associated with many human diseases and is an important factor for donor selection in allogeneic hematopoietic stem cell transplantation, the molecular determinant of functional diversity among various alleles is unclear. In this study we found that KIR2DL2/L3 with glutamic acid at position 35 (E35) are functionally stronger than those with glutamine at the same position (Q35). Cytotoxicity assay showed that NK cells from HLA-C1 positive donors with KIR2DL2/L3-E35 could kill more target cells lacking their ligands than NK cells with the weaker -Q35 alleles, indicating better licensing of KIR2DL2/L3+ NK cells with the stronger alleles. Molecular modeling analysis reveals that the glutamic acid, which is negatively charged, interacts with positively charged histidine located at position 55, thereby stabilizing KIR2DL2/L3 dimer and reducing entropy loss when KIR2DL2/3 binds to HLA-C ligand. The results of this study will be important for future studies of KIR2DL2/L3-associated diseases as well as for donor selection in allogeneic stem cell transplantation.

Evaluation of genetic diversity and population structure of West-Central Indian cattle breeds.

PubMed

Shah, Tejas M; Patel, Jaina S; Bhong, Chandrakant D; Doiphode, Aakash; Umrikar, Uday D; Parmar, Shivnandan S; Rank, Dharamshibhai N; Solanki, Jitendra V; Joshi, Chaitanya G

2013-08-01

Evaluations of genetic diversity in domestic livestock populations are necessary to implement region-specific conservation measures. We determined the genetic diversity and evolutionary relationships among eight geographically and phenotypically diverse cattle breeds indigenous to west-central India by genotyping these animals for 22 microsatellite loci. A total of 326 alleles were detected, and the expected heterozygosity ranged from 0.614 (Kenkatha) to 0.701 (Dangi). The mean number of alleles among the cattle breeds ranged from 7.182 (Khillar) to 9.409 (Gaolao). There were abundant genetic variations displayed within breeds, and the genetic differentiation was also high between the Indian cattle breeds, which displayed 15.9% of the total genetic differentiation among the different breeds. The genetic differentiation (pairwise FST ) among the eight Indian breeds varied from 0.0126 for the Kankrej-Malvi pair to 0.2667 for Khillar-Kenkatha pair. The phylogeny, principal components analysis, and structure analysis further supported close grouping of Kankrej, Malvi, Nimari and Gir; Gaolao and Kenkatha, whereas Dangi and Khillar remained at distance from other breeds. © 2012 The Authors, Animal Genetics © 2012 Stichting International Foundation for Animal Genetics.

Heritable Individual-Specific and Allele-Specific Chromatin Signatures in Humans

PubMed Central

McDaniell, Ryan; Lee, Bum-Kyu; Song, Lingyun; Liu, Zheng; Boyle, Alan P.; Erdos, Michael R.; Scott, Laura J.; Morken, Mario A.; Kucera, Katerina S.; Battenhouse, Anna; Keefe, Damian; Collins, Francis S.; Willard, Huntington F.; Lieb, Jason D.; Furey, Terrence S.; Crawford, Gregory E.; Iyer, Vishwanath R.; Birney, Ewan

2010-01-01

The extent to which variation in chromatin structure and transcription factor binding may influence gene expression, and thus underlie or contribute to variation in phenotype, is unknown. To address this question, we cataloged both individual-to-individual variation and differences between homologous chromosomes within the same individual (allele-specific variation) in chromatin structure and transcription factor binding in lymphoblastoid cells derived from individuals of geographically diverse ancestry. Ten percent of active chromatin sites were individual-specific; a similar proportion were allele-specific. Both individual-specific and allele-specific sites were commonly transmitted from parent to child, which suggests that they are heritable features of the human genome. Our study shows that heritable chromatin status and transcription factor binding differ as a result of genetic variation and may underlie phenotypic variation in humans. PMID:20299549

Novel microsatellite markers for the oriental fruit moth Grapholita molesta (Lepidoptera: Tortricidae) and effects of null alleles on population genetics analyses.

PubMed

Song, W; Cao, L-J; Wang, Y-Z; Li, B-Y; Wei, S-J

2017-06-01

The oriental fruit moth (OFM) Grapholita molesta (Lepidoptera: Tortricidae) is an important economic pest of stone and pome fruits worldwide. We sequenced the OFM genome using next-generation sequencing and characterized the microsatellite distribution. In total, 56,674 microsatellites were identified, with 11,584 loci suitable for primer design. Twenty-seven polymorphic microsatellites, including 24 loci with trinucleotide repeat and three with pentanucleotide repeat, were validated in 95 individuals from four natural populations. The allele numbers ranged from 4 to 40, with an average value of 13.7 per locus. A high frequency of null alleles was observed in most loci developed for the OFM. Three marker panels, all of the loci, nine loci with the lowest null allele frequencies, and nine loci with the highest null allele frequencies, were established for population genetics analyses. The null allele influenced estimations of genetic diversity parameters but not the OFM's genetic structure. Both a STRUCTURE analysis and a discriminant analysis of principal components, using the three marker panels, divided the four natural populations into three groups. However, more individuals were incorrectly assigned by the STRUCTURE analysis when the marker panel with the highest null allele frequency was used compared with the other two panels. Our study provides empirical research on the effects of null alleles on population genetics analyses. The microsatellites developed will be valuable markers for genetic studies of the OFM.

Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran

PubMed Central

Abbasi, Shabnam; Afsharzadeh, Saeed; Saeidi, Hojjatollah; Triest, Ludwig

2016-01-01

Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata) giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros) and desert zones (Kavir), with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU). At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was revealed among

Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran.

PubMed

Abbasi, Shabnam; Afsharzadeh, Saeed; Saeidi, Hojjatollah; Triest, Ludwig

2016-01-01

Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata) giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros) and desert zones (Kavir), with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU). At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was revealed among

Molecular Genetic Diversity of Major Indian Rice Cultivars over Decadal Periods

PubMed Central

Deborah, Dondapati Annekitty; Vipparla, Abhilash; Anuradha, Ghanta; Siddiq, Ebrahimali Abubacker; Vemireddy, Lakshminarayana Reddy

2013-01-01

Genetic diversity in representative sets of high yielding varieties of rice released in India between 1970 and 2010 was studied at molecular level employing hypervariable microsatellite markers. Of 64 rice SSR primer pairs studied, 52 showed polymorphism, when screened in 100 rice genotypes. A total of 184 alleles was identified averaging 3.63 alleles per locus. Cluster analysis clearly grouped the 100 genotypes into their respective decadal periods i.e., 1970s, 1980s, 1990s and 2000s. The trend of diversity over the decadal periods estimated based on the number of alleles (Na), allelic richness (Rs), Nei’s genetic diversity index (He), observed heterozygosity (Ho) and polymorphism information content (PIC) revealed increase of diversity over the periods in year of releasewise and longevitywise classification of rice varieties. Analysis of molecular variance (AMOVA) suggested more variation in within the decadal periods than among the decades. Pairwise comparison of population differentiation (Fst) among decadal periods showed significant difference between all the pairs except a few. Analysis of trends of appearing and disappearing alleles over decadal periods showed an increase in the appearance of alleles and decrease in disappearance in both the categories of varieties. It was obvious from the present findings, that genetic diversity was progressively on the rise in the varieties released during the decadal periods, between 1970s and 2000s. PMID:23805204

Analysis of Genetic Diversity and Population Structure of Rice Germplasm from North-Eastern Region of India and Development of a Core Germplasm Set

PubMed Central

Singh, Amit Kumar; Kumar, Sundeep; Srinivasan, Kalyani; Tyagi, R. K.; Ahmad, Altaf; Singh, N. K.; Singh, Rakesh

2014-01-01

The North-Eastern region (NER) of India, comprising of Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura, is a hot spot for genetic diversity and the most probable origin of rice. North-east rice collections are known to possess various agronomically important traits like biotic and abiotic stress tolerance, unique grain and cooking quality. The genetic diversity and associated population structure of 6,984 rice accessions, originating from NER, were assessed using 36 genome wide unlinked single nucleotide polymorphism (SNP) markers distributed across the 12 rice chromosomes. All of the 36 SNP loci were polymorphic and bi-allelic, contained five types of base substitutions and together produced nine types of alleles. The polymorphic information content (PIC) ranged from 0.004 for Tripura to 0.375 for Manipur and major allele frequency ranged from 0.50 for Assam to 0.99 for Tripura. Heterozygosity ranged from 0.002 in Nagaland to 0.42 in Mizoram and gene diversity ranged from 0.006 in Arunachal Pradesh to 0.50 in Manipur. The genetic relatedness among the rice accessions was evaluated using an unrooted phylogenetic tree analysis, which grouped all accessions into three major clusters. For determining population structure, populations K = 1 to K = 20 were tested and population K = 3 was present in all the states, with the exception of Meghalaya and Manipur where, K = 5 and K = 4 populations were present, respectively. Principal Coordinate Analysis (PCoA) showed that accessions were distributed according to their population structure. AMOVA analysis showed that, maximum diversity was partitioned at the individual accession level (73% for Nagaland, 58% for Arunachal Pradesh and 57% for Tripura). Using POWERCORE software, a core set of 701 accessions was obtained, which accounted for approximately 10% of the total NE India collections, representing 99.9% of the allelic diversity. The rice core set developed will be a

Genetic Diversity in Nothofagus alessandrii (Fagaceae), an Endangered Endemic Tree Species of the Coastal Maulino Forest of Central Chile

PubMed Central

Torres-Díaz, Cristian; Ruiz, Eduardo; González, Fidelina; Fuentes, Glenda; Cavieres, Lohengrin A.

2007-01-01

Background and Aims The endemic tree Nothofagus alessandrii (Fagaceae) has been historically restricted to the coastal range of Region VII of central Chile, and its forests have been increasingly destroyed and fragmented since the end of the 19th century. In this study, the patterns of within- and among-population genetic diversity in seven fragments of this endangered narrowly endemic tree were examined. Methods Allozyme electrophoresis of seven loci of N. alessandrii was used to estimate genetic diversity, genetic structure and gene flow. Key Results High levels of genetic diversity were found as shown by mean expected heterozygosity (He = 0·182 ± 0·034), percentage of polymorphic loci (Pp = 61·2 %), mean number of alleles per locus (A = 1·8) and mean number of alleles per polymorphic locus (Ap = 2·3). Genetic differentiation was also high (GST = 0·257 and Nm = 0·7). These values are high compared with more widespread congeneric species. Conclusions Despite its endemic status and restricted geographical range N. alessandrii showed high levels of genetic diversity. The observed patterns of diversity are explained in part by historical processes and more recent human fragmentation. PMID:17513870

The effect of rare alleles on estimated genomic relationships from whole genome sequence data.

PubMed

Eynard, Sonia E; Windig, Jack J; Leroy, Grégoire; van Binsbergen, Rianne; Calus, Mario P L

2015-03-12

Relationships between individuals and inbreeding coefficients are commonly used for breeding decisions, but may be affected by the type of data used for their estimation. The proportion of variants with low Minor Allele Frequency (MAF) is larger in whole genome sequence (WGS) data compared to Single Nucleotide Polymorphism (SNP) chips. Therefore, WGS data provide true relationships between individuals and may influence breeding decisions and prioritisation for conservation of genetic diversity in livestock. This study identifies differences between relationships and inbreeding coefficients estimated using pedigree, SNP or WGS data for 118 Holstein bulls from the 1000 Bull genomes project. To determine the impact of rare alleles on the estimates we compared three scenarios of MAF restrictions: variants with a MAF higher than 5%, variants with a MAF higher than 1% and variants with a MAF between 1% and 5%. We observed significant differences between estimated relationships and, although less significantly, inbreeding coefficients from pedigree, SNP or WGS data, and between MAF restriction scenarios. Computed correlations between pedigree and genomic relationships, within groups with similar relationships, ranged from negative to moderate for both estimated relationships and inbreeding coefficients, but were high between estimates from SNP and WGS (0.49 to 0.99). Estimated relationships from genomic information exhibited higher variation than from pedigree. Inbreeding coefficients analysis showed that more complete pedigree records lead to higher correlation between inbreeding coefficients from pedigree and genomic data. Finally, estimates and correlations between additive genetic (A) and genomic (G) relationship matrices were lower, and variances of the relationships were larger when accounting for allele frequencies than without accounting for allele frequencies. Using pedigree data or genomic information, and including or excluding variants with a MAF below 5

Natural Selection and Origin of a Melanistic Allele in North American Gray Wolves.

PubMed

Schweizer, Rena M; Durvasula, Arun; Smith, Joel; Vohr, Samuel H; Stahler, Daniel R; Galaverni, Marco; Thalmann, Olaf; Smith, Douglas W; Randi, Ettore; Ostrander, Elaine A; Green, Richard E; Lohmueller, Kirk E; Novembre, John; Wayne, Robert K

2018-05-01

Pigmentation is often used to understand how natural selection affects genetic variation in wild populations since it can have a simple genetic basis, and can affect a variety of fitness-related traits (e.g., camouflage, thermoregulation, and sexual display). In gray wolves, the K locus, a β-defensin gene, causes black coat color via a dominantly inherited KB allele. The allele is derived from dog-wolf hybridization and is at high frequency in North American wolf populations. We designed a DNA capture array to probe the geographic origin, age, and number of introgression events of the KB allele in a panel of 331 wolves and 20 dogs. We found low diversity in KB, but not ancestral ky, wolf haplotypes consistent with a selective sweep of the black haplotype across North America. Further, North American wolf KB haplotypes are monophyletic, suggesting that a single adaptive introgression from dogs to wolves most likely occurred in the Northwest Territories or Yukon. We use a new analytical approach to date the origin of the KB allele in Yukon wolves to between 1,598 and 7,248 years ago, suggesting that introgression with early Native American dogs was the source. Using population genetic simulations, we show that the K locus is undergoing natural selection in four wolf populations. We find evidence for balancing selection, specifically in Yellowstone wolves, which could be a result of selection for enhanced immunity in response to distemper. With these data, we demonstrate how the spread of an adaptive variant may have occurred across a species' geographic range.

Genetic diversity of Afrikaner cattle in southern Africa.

PubMed

Pienaar, Lené; Grobler, J Paul; Scholtz, Michiel M; Swart, Hannelize; Ehlers, Karen; Marx, Munro; MacNeil, Michael D; Neser, Frederick W C

2018-02-01

The Afrikaner is an indigenous South African breed of "Sanga" type beef cattle along with breeds such as the Drakensberger and Nguni. Six composite breeds have been developed from crosses with the Afrikaner. Additionally, Afrikaner has been the base from which exotic breeds were established in South Africa through backcrossing. The study examined genetic diversity of Afrikaner cattle by genotyping 1257 animals from 27 herds in different geographic areas of South Africa and Namibia using 11 microsatellite markers. Multiple-locus assignment, performed using the Bayesian clustering algorithm of STRUCTURE, revealed three underlying genotypic groups. These groups were not geographically localized. Across herds and markers, the proportion of unbiased heterozygosity ranged from 0.49 to 0.72 averaging 0.57; mean number of alleles per locus ranged from 3.18 to 7.09, averaging 4.81; and allelic richness ranged from 2.35 to 3.38, averaging 2.67. It is concluded that a low inbreeding level of 2.7% and a moderate to high degree of variation still persists within the Afrikaner cattle breed, despite the recent decline in numbers of animals.

Global phylogeography of the avian malaria pathogen Plasmodium relictum based on MSP1 allelic diversity

USGS Publications Warehouse

Hellgren, Olof; Atkinson, Carter T.; Bensch, Staffan; Albayrak, Tamer; Dimitrov, Dimitar; Ewen, John G.; Kim, Kyeong Soon; Lima, Marcos R.; Martin, Lynn; Palinauskas, Vaidas; Ricklefs, Robert; Sehgal, Ravinder N. M.; Gediminas, Valkiunas; Tsuda, Yoshio; Marzal, Alfonso

2015-01-01

Knowing the genetic variation that occurs in pathogen populations and how it is distributed across geographical areas is essential to understand parasite epidemiology, local patterns of virulence, and evolution of host-resistance. In addition, it is important to identify populations of pathogens that are evolutionarily independent and thus ‘free’ to adapt to hosts and environments. Here, we investigated genetic variation in the globally distributed, highly invasive avian malaria parasite Plasmodium relictum, which has several distinctive mitochondrial haplotyps (cyt b lineages, SGS1, GRW11 and GRW4). The phylogeography of P. relictum was accessed using the highly variable nuclear gene merozoite surface protein 1 (MSP1), a gene linked to the invasion biology of the parasite. We show that the lineage GRW4 is evolutionarily independent of GRW11 and SGS1 whereas GRW11 and SGS1 share MSP1 alleles and thus suggesting the presence of two distinct species (GRW4 versus SGS1 and GRW11). Further, there were significant differences in the global distribution of MSP1 alleles with differences between GRW4 alleles in the New and the Old World. For SGS1, a lineage formerly believed to have both tropical and temperate transmission, there were clear differences in MSP1 alleles transmitted in tropical Africa compared to the temperate regions of Europe and Asia. Further, we highlight the occurrence of multiple MSP1 alleles in GRW4 isolates from the Hawaiian Islands, where the parasite has contributed to declines and extinctions of endemic forest birds since it was introduced. This study stresses the importance of multiple independent loci for understanding patterns of transmission and evolutionary independence across avian malaria parasites.

Assessing the impact of breeding strategies on inherited disorders and genetic diversity in dogs.

PubMed

Leroy, Grégoire; Rognon, Xavier

2012-12-01

In the context of management of genetic diversity and control of genetic disorders within dog breeds, a method is proposed for assessing the impact of different breeding strategies that takes into account the genealogical information specific to a given breed. Two types of strategies were investigated: (1) eradication of an identified monogenic recessive disorder, taking into account three different mating limitations and various initial allele frequencies; and (2) control of the population sire effect by limiting the number of offspring per reproducer. The method was tested on four dog breeds: Braque Saint Germain, Berger des Pyrénées, Coton de Tulear and Epagneul Breton. Breeding policies, such as the removal of all carriers from the reproduction pool, may have a range of effects on genetic diversity, depending on the breed and the frequency of deleterious alleles. Limiting the number of offspring per reproducer may also have a positive impact on genetic diversity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Parasites and parallel divergence of the number of individual MHC alleles between sympatric three-spined stickleback Gasterosteus aculeatus morphs in Iceland.

PubMed

Natsopoulou, M E; Pálsson, S; Ólafsdóttir, G Á

2012-10-01

Two pairs of sympatric three-spined stickleback Gasterosteus aculeatus morphs and two single morph populations inhabiting mud and lava or rocky benthic habitats in four Icelandic lakes were screened for parasites and genotyped for MHC class IIB diversity. Parasitic infection differed consistently between G. aculeatus from different benthic habitats. Gasterosteus aculeatus from the lava or rocky habitats were more heavily infected in all lakes. A parallel pattern was also found in individual MHC allelic variation with lava G. aculeatus morphs exhibiting lower levels of variation than the mud morphs. Evidence for selective divergence in MHC allele number is ambiguous but supported by two findings in addition to the parallel pattern observed. MHC allele diversity was not consistent with diversity reported at neutral markers (microsatellites) and in Þingvallavatn the most common number of alleles in each morph was associated with lower infection levels. In the Þingvallavatn lava morph, lower infection levels by the two most common parasites, Schistocephalus solidus and Diplostomum baeri, were associated with different MHC allele numbers. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Tracking human migrations by the analysis of the distribution of HLA alleles, lineages and haplotypes in closed and open populations

PubMed Central

Vina, Marcelo A. Fernandez; Hollenbach, Jill A.; Lyke, Kirsten E.; Sztein, Marcelo B.; Maiers, Martin; Klitz, William; Cano, Pedro; Mack, Steven; Single, Richard; Brautbar, Chaim; Israel, Shosahna; Raimondi, Eduardo; Khoriaty, Evelyne; Inati, Adlette; Andreani, Marco; Testi, Manuela; Moraes, Maria Elisa; Thomson, Glenys; Stastny, Peter; Cao, Kai

2012-01-01

The human leucocyte antigen (HLA) system shows extensive variation in the number and function of loci and the number of alleles present at any one locus. Allele distribution has been analysed in many populations through the course of several decades, and the implementation of molecular typing has significantly increased the level of diversity revealing that many serotypes have multiple functional variants. While the degree of diversity in many populations is equivalent and may result from functional polymorphism(s) in peptide presentation, homogeneous and heterogeneous populations present contrasting numbers of alleles and lineages at the loci with high-density expression products. In spite of these differences, the homozygosity levels are comparable in almost all of them. The balanced distribution of HLA alleles is consistent with overdominant selection. The genetic distances between outbred populations correlate with their geographical locations; the formal genetic distance measurements are larger than expected between inbred populations in the same region. The latter present many unique alleles grouped in a few lineages consistent with limited founder polymorphism in which any novel allele may have been positively selected to enlarge the communal peptide-binding repertoire of a given population. On the other hand, it has been observed that some alleles are found in multiple populations with distinctive haplotypic associations suggesting that convergent evolution events may have taken place as well. It appears that the HLA system has been under strong selection, probably owing to its fundamental role in varying immune responses. Therefore, allelic diversity in HLA should be analysed in conjunction with other genetic markers to accurately track the migrations of modern humans. PMID:22312049

Geographical gradient of the eIF4E alleles conferring resistance to potyviruses in pea (Pisum) germplasm.

PubMed

Konečná, Eva; Šafářová, Dana; Navrátil, Milan; Hanáček, Pavel; Coyne, Clarice; Flavell, Andrew; Vishnyakova, Margarita; Ambrose, Mike; Redden, Robert; Smýkal, Petr

2014-01-01

The eukaryotic translation initiation factor 4E was shown to be involved in resistance against several potyviruses in plants, including pea. We combined our knowledge of pea germplasm diversity with that of the eIF4E gene to identify novel genetic diversity. Germplasm of 2803 pea accessions was screened for eIF4E intron 3 length polymorphism, resulting in the detection of four eIF4E(A-B-C-S) variants, whose distribution was geographically structured. The eIF4E(A) variant conferring resistance to the P1 PSbMV pathotype was found in 53 accessions (1.9%), of which 15 were landraces from India, Afghanistan, Nepal, and 7 were from Ethiopia. A newly discovered variant, eIF4E(B), was present in 328 accessions (11.7%) from Ethiopia (29%), Afghanistan (23%), India (20%), Israel (25%) and China (39%). The eIF4E(C) variant was detected in 91 accessions (3.2% of total) from India (20%), Afghanistan (33%), the Iberian Peninsula (22%) and the Balkans (9.3%). The eIF4E(S) variant for susceptibility predominated as the wild type. Sequencing of 73 samples, identified 34 alleles at the whole gene, 26 at cDNA and 19 protein variants, respectively. Fifteen alleles were virologically tested and 9 alleles (eIF4E(A-1-2-3-4-5-6-7), eIF4E(B-1), eIF4E(C-2)) conferred resistance to the P1 PSbMV pathotype. This work identified novel eIF4E alleles within geographically structured pea germplasm and indicated their independent evolution from the susceptible eIF4E(S1) allele. Despite high variation present in wild Pisum accessions, none of them possessed resistance alleles, supporting a hypothesis of distinct mode of evolution of resistance in wild as opposed to crop species. The Highlands of Central Asia, the northern regions of the Indian subcontinent, Eastern Africa and China were identified as important centers of pea diversity that correspond with the diversity of the pathogen. The series of alleles identified in this study provides the basis to study the co-evolution of potyviruses and the

Geographical Gradient of the eIF4E Alleles Conferring Resistance to Potyviruses in Pea (Pisum) Germplasm

PubMed Central

Konečná, Eva; Šafářová, Dana; Navrátil, Milan; Hanáček, Pavel; Coyne, Clarice; Flavell, Andrew; Vishnyakova, Margarita; Ambrose, Mike; Redden, Robert; Smýkal, Petr

2014-01-01

Background The eukaryotic translation initiation factor 4E was shown to be involved in resistance against several potyviruses in plants, including pea. We combined our knowledge of pea germplasm diversity with that of the eIF4E gene to identify novel genetic diversity. Methodology/Principal findings Germplasm of 2803 pea accessions was screened for eIF4E intron 3 length polymorphism, resulting in the detection of four eIF4EA-B-C-S variants, whose distribution was geographically structured. The eIF4EA variant conferring resistance to the P1 PSbMV pathotype was found in 53 accessions (1.9%), of which 15 were landraces from India, Afghanistan, Nepal, and 7 were from Ethiopia. A newly discovered variant, eIF4EB, was present in 328 accessions (11.7%) from Ethiopia (29%), Afghanistan (23%), India (20%), Israel (25%) and China (39%). The eIF4EC variant was detected in 91 accessions (3.2% of total) from India (20%), Afghanistan (33%), the Iberian Peninsula (22%) and the Balkans (9.3%). The eIF4ES variant for susceptibility predominated as the wild type. Sequencing of 73 samples, identified 34 alleles at the whole gene, 26 at cDNA and 19 protein variants, respectively. Fifteen alleles were virologically tested and 9 alleles (eIF4EA-1-2-3-4-5-6-7, eIF4EB-1, eIF4EC-2) conferred resistance to the P1 PSbMV pathotype. Conclusions/Significance This work identified novel eIF4E alleles within geographically structured pea germplasm and indicated their independent evolution from the susceptible eIF4ES1 allele. Despite high variation present in wild Pisum accessions, none of them possessed resistance alleles, supporting a hypothesis of distinct mode of evolution of resistance in wild as opposed to crop species. The Highlands of Central Asia, the northern regions of the Indian subcontinent, Eastern Africa and China were identified as important centers of pea diversity that correspond with the diversity of the pathogen. The series of alleles identified in this study provides the basis

Successive range expansion promotes diversity and accelerates evolution in spatially structured microbial populations.

PubMed

Goldschmidt, Felix; Regoes, Roland R; Johnson, David R

2017-09-01

Successive range expansions occur within all domains of life, where one population expands first (primary expansion) and one or more secondary populations then follow (secondary expansion). In general, genetic drift reduces diversity during range expansion. However, it is not clear whether the same effect applies during successive range expansion, mainly because the secondary population must expand into space occupied by the primary population. Here we used an experimental microbial model system to show that, in contrast to primary range expansion, successive range expansion promotes local population diversity. Because of mechanical constraints imposed by the presence of the primary population, the secondary population forms fractal-like dendritic structures. This divides the advancing secondary population into many small sub-populations and promotes intermixing between the primary and secondary populations. We further developed a mathematical model to simulate the formation of dendritic structures in the secondary population during succession. By introducing mutations in the primary or dendritic secondary populations, we found that mutations are more likely to accumulate in the dendritic secondary populations. Our results thus show that successive range expansion can promote intermixing over the short term and increase genetic diversity over the long term. Our results therefore have potentially important implications for predicting the ecological processes and evolutionary trajectories of microbial communities.

HLA class-I and class-II allele frequencies and two-locus haplotypes in Melanesians of Vanuatu and New Caledonia.

PubMed

Maitland, K; Bunce, M; Harding, R M; Barnardo, M C N M; Clegg, J B; Welsh, K; Bowden, D K; Williams, T N

2004-12-01

HLA class-I and class-II allele frequencies and two-locus haplotypes were examined in 367 unrelated Melanesians living on the islands of Vanuatu and New Caledonia. Diversity at all HLA class-I and class-II loci was relatively limited. In class-I loci, three HLA-A allelic groups (HLA-A*24, HLA-A*34 and HLA-A*11), seven HLA-B alleles or allelic groups (HLA-B*1506, HLA-B*5602, HLA-B*13, HLA-B*5601, HLA-B*4001, HLA-B*4002 and HLA-B*2704) and four HLA-C alleles or allelic groups (HLA-Cw*04, HLA-Cw*01, HLA-Cw*0702 and HLA-Cw*15) constituted more than 90% of the alleles observed. In the class-II loci, four HLA-DRB1 alleles (HLA-DRB1*15, HLA-DRB1*11, HLA-DRB1*04 and HLA-DRB1*16), three HLA-DRB3-5 alleles (HLA-DRB3*02, HLA-DRB4*01 and HLA-DRB5*01/02) and five HLA-DQB1 alleles (HLA-DQB1*0301, HLA-DQB1*04, HLA-DQB1*05, HLA-DQB1*0601 and HLA-DQB1*0602) constituted over 93, 97 and 98% of the alleles observed, respectively. Homozygosity showed significant departures from expected levels for neutrality based on allele frequency (i.e. excess diversity) at the HLA-B, HLA-Cw, HLA-DQB1 and HLA-DRB3/5 loci on some islands. The locus with the strongest departure from neutrality was HLA-DQB1, homozygosity being significantly lower than expected on all islands except New Caledonia. No consistent pattern was demonstrated for any HLA locus in relation to malaria endemicity.

Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2.

PubMed

Chan, Elizabeth A W; Teng, Grace; Corbett, Elizabeth; Choudhury, Kingshuk Roy; Bassing, Craig H; Schatz, David G; Krangel, Michael S

2013-11-26

Allelic exclusion requires that the two alleles at antigen-receptor loci attempt to recombine variable (V), diversity (D), and joining (J) gene segments [V(D)J recombination] asynchronously in nuclei of developing lymphocytes. It previously was shown that T-cell receptor β (Tcrb) alleles frequently and stochastically associate with the nuclear lamina and pericentromeric heterochromatin in CD4(-)CD8(-) thymocytes. Moreover, rearranged alleles were underrepresented at these locations. Here we used 3D immunofluorescence in situ hybridization to identify recently rearranged Tcrb alleles based on the accumulation of the DNA-repair protein 53BP1. We found that Tcrb alleles recombine asynchronously in double-negative thymocytes and that V(D)J recombination is suppressed on peripheral as compared with central Tcrb alleles. Moreover, the recombination events that did take place at the nuclear periphery preferentially occurred on Tcrb alleles that were partially dissociated from the nuclear lamina. To understand better the mechanism by which V(D)J recombination is suppressed at the nuclear periphery, we evaluated the subnuclear distribution of recombination-activating gene 2 (RAG2) protein. We found that RAG2 abundance was reduced at the nuclear periphery. Moreover, RAG2 was distributed differently from RNA polymerase II and histone H3K4 trimethylation. Our data suggest that the nuclear periphery suppresses V(D)J recombination, at least in part, by segregating Tcrb alleles from RAG proteins.

[Genetic diversity of common wheat varieties at the gliadin-coding loci].

PubMed

Novoselskaya-Dragovich, A Yu; Bespalova, L A; Shishkina, A A; Melnik, V A; Upelniek, V P; Fisenko, A V; Dedova, L V; Kudryavtsev, A M

2015-03-01

One hundred and fifty Russian and foreign winter common wheat varieties were examined by the PAGE method. A total of 70 alleles were identified at seven gliadin-coding loci. It was demonstrated that 42% of varieties were heterogeneous, i.e., were represented by a number of genotypes, while 52% of varieties were homogeneous. A unique combination of gliadin alleles was typical of 91.3% of examined varieties, while 8.7% of varieties had identical alleles of all gliadin-coding loci and were indistinguishable. Frequent and rare alleles were identified, with the former accounting for 18.6% of all alleles. It was demonstrated that allelic diversity at the Gli-2 loci (47 alleles) was almost twice that at the Gli-1 loci (23 loci) and was determined by the number of rare alleles. New alleles for the winter common wheat, including three alleles of the GliA2 locus and two alleles of the Gli-B2 locus, were determined. A tendency toward a reduction of the genetic diversity level in modern varieties, which was due to the use of identical parental varieties in breeding programs, was identified.

Evidence of cryptic introgression in tomato (Solanum lycopersicum L.) based on wild tomato species alleles

PubMed Central

2012-01-01

Background Many highly beneficial traits (e.g. disease or abiotic stress resistance) have been transferred into crops through crosses with their wild relatives. The 13 recognized species of tomato (Solanum section Lycopersicon) are closely related to each other and wild species genes have been extensively used for improvement of the crop, Solanum lycopersicum L. In addition, the lack of geographical barriers has permitted natural hybridization between S. lycopersicum and its closest wild relative Solanum pimpinellifolium in Ecuador, Peru and northern Chile. In order to better understand patterns of S. lycopersicum diversity, we sequenced 47 markers ranging in length from 130 to 1200 bp (total of 24 kb) in genotypes of S. lycopersicum and wild tomato species S. pimpinellifolium, Solanum arcanum, Solanum peruvianum, Solanum pennellii and Solanum habrochaites. Between six and twelve genotypes were comparatively analyzed per marker. Several of the markers had previously been hypothesized as carrying wild species alleles within S. lycopersicum, i.e., cryptic introgressions. Results Each marker was mapped with high confidence (e<1 x 10-30) to a single genomic location using BLASTN against tomato whole genome shotgun chromosomes (SL2.40) database. Neighbor-joining trees showed high mean bootstrap support (86.8 ± 2.34%) for distinguishing red-fruited from green-fruited taxa for 38 of the markers. Hybridization and parsimony splits networks, genomic map positions of markers relative to documented introgressions, and historical origins of accessions were used to interpret evolutionary patterns at nine markers with putatively introgressed alleles. Conclusion Of the 47 genetic markers surveyed in this study, four were involved in linkage drag on chromosome 9 during introgression breeding, while alleles at five markers apparently originated from natural hybridization with S. pimpinellifolium and were associated with primitive genotypes of S. lycopersicum. The positive

Evidence of cryptic introgression in tomato (Solanum lycopersicum L.) based on wild tomato species alleles.

PubMed

Labate, Joanne A; Robertson, Larry D

2012-08-07

Many highly beneficial traits (e.g. disease or abiotic stress resistance) have been transferred into crops through crosses with their wild relatives. The 13 recognized species of tomato (Solanum section Lycopersicon) are closely related to each other and wild species genes have been extensively used for improvement of the crop, Solanum lycopersicum L. In addition, the lack of geographical barriers has permitted natural hybridization between S. lycopersicum and its closest wild relative Solanum pimpinellifolium in Ecuador, Peru and northern Chile. In order to better understand patterns of S. lycopersicum diversity, we sequenced 47 markers ranging in length from 130 to 1200 bp (total of 24 kb) in genotypes of S. lycopersicum and wild tomato species S. pimpinellifolium, Solanum arcanum, Solanum peruvianum, Solanum pennellii and Solanum habrochaites. Between six and twelve genotypes were comparatively analyzed per marker. Several of the markers had previously been hypothesized as carrying wild species alleles within S. lycopersicum, i.e., cryptic introgressions. Each marker was mapped with high confidence (e<1 x 10-30) to a single genomic location using BLASTN against tomato whole genome shotgun chromosomes (SL2.40) database. Neighbor-joining trees showed high mean bootstrap support (86.8 ± 2.34%) for distinguishing red-fruited from green-fruited taxa for 38 of the markers. Hybridization and parsimony splits networks, genomic map positions of markers relative to documented introgressions, and historical origins of accessions were used to interpret evolutionary patterns at nine markers with putatively introgressed alleles. Of the 47 genetic markers surveyed in this study, four were involved in linkage drag on chromosome 9 during introgression breeding, while alleles at five markers apparently originated from natural hybridization with S. pimpinellifolium and were associated with primitive genotypes of S. lycopersicum. The positive identification of introgressed

Genetic diversity and species diversity of stream fishes covary across a land-use gradient.

PubMed

Blum, Michael J; Bagley, Mark J; Walters, David M; Jackson, Suzanne A; Daniel, F Bernard; Chaloud, Deborah J; Cade, Brian S

2012-01-01

Genetic diversity and species diversity are expected to covary according to area and isolation, but may not always covary with environmental heterogeneity. In this study, we examined how patterns of genetic and species diversity in stream fishes correspond to local and regional environmental conditions. To do so, we compared population size, genetic diversity and divergence in central stonerollers (Campostoma anomalum) to measures of species diversity and turnover in stream fish assemblages among similarly sized watersheds across an agriculture-forest land-use gradient in the Little Miami River basin (Ohio, USA). Significant correlations were found in many, but not all, pair-wise comparisons. Allelic richness and species richness were strongly correlated, for example, but diversity measures based on allele frequencies and assemblage structure were not. In-stream conditions related to agricultural land use were identified as significant predictors of genetic diversity and species diversity. Comparisons to population size indicate, however, that genetic diversity and species diversity are not necessarily independent and that variation also corresponds to watershed location and glaciation history in the drainage basin. Our findings demonstrate that genetic diversity and species diversity can covary in stream fish assemblages, and illustrate the potential importance of scaling observations to capture responses to hierarchical environmental variation. More comparisons according to life history variation could further improve understanding of conditions that give rise to parallel variation in genetic diversity and species diversity, which in turn could improve diagnosis of anthropogenic influences on aquatic ecosystems.

Genetic diversity and species diversity of stream fishes covary across a land-use gradient

USGS Publications Warehouse

Blum, M.J.; Bagley, M.J.; Walters, D.M.; Jackson, S.A.; Daniel, F.B.; Chaloud, D.J.; Cade, B.S.

2012-01-01

Genetic diversity and species diversity are expected to covary according to area and isolation, but may not always covary with environmental heterogeneity. In this study, we examined how patterns of genetic and species diversity in stream fishes correspond to local and regional environmental conditions. To do so, we compared population size, genetic diversity and divergence in central stonerollers (Campostoma anomalum) to measures of species diversity and turnover in stream fish assemblages among similarly sized watersheds across an agriculture-forest land-use gradient in the Little Miami River basin (Ohio, USA). Significant correlations were found in many, but not all, pair-wise comparisons. Allelic richness and species richness were strongly correlated, for example, but diversity measures based on allele frequencies and assemblage structure were not. In-stream conditions related to agricultural land use were identified as significant predictors of genetic diversity and species diversity. Comparisons to population size indicate, however, that genetic diversity and species diversity are not necessarily independent and that variation also corresponds to watershed location and glaciation history in the drainage basin. Our findings demonstrate that genetic diversity and species diversity can covary in stream fish assemblages, and illustrate the potential importance of scaling observations to capture responses to hierarchical environmental variation. More comparisons according to life history variation could further improve understanding of conditions that give rise to parallel variation in genetic diversity and species diversity, which in turn could improve diagnosis of anthropogenic influences on aquatic ecosystems. ?? 2011 Springer-Verlag.

Genetic diversity in butterflies: Interactive effects of habitat fragmentation and climate-driven range expansion.

PubMed

Hill, Jane K; Hughes, Clare L; Dytham, Calvin; Searle, Jeremy B

2006-03-22

Some species are expanding their ranges polewards during current climate warming. However, anthropogenic fragmentation of suitable habitat is affecting expansion rates and here we investigate interactions between range expansion, habitat fragmentation and genetic diversity. We examined three closely related Satyrinae butterflies, which differ in their habitat associations, from six sites along a transect in England from distribution core to expanding range margin. There was a significant decline in allozyme variation towards an expanding range margin in Pararge aegeria, which has the most restricted habitat availability, but not in Pyronia tithonus whose habitat is more widely available, or in a non-expanding 'control species' (Maniola jurtina). Moreover, data from another transect in Scotland indicated that declines in genetic diversity in P. aegeria were evident only on the transect in England, which had greater habitat fragmentation. Our results indicate that fragmentation of breeding habitats leads to more severe founder events during colonization, resulting in reduced diversity in marginal populations in more specialist species. The continued widespread loss of suitable habitats in the future may increase the likelihood of loss of genetic diversity in expanding species, which may affect whether or not species can adapt to future environmental change.

Genetic Diversity and Linkage Disequilibrium in Chinese Bread Wheat (Triticum aestivum L.) Revealed by SSR Markers

PubMed Central

Hao, Chenyang; Wang, Lanfen; Ge, Hongmei; Dong, Yuchen; Zhang, Xueyong

2011-01-01

Two hundred and fifty bread wheat lines, mainly Chinese mini core accessions, were assayed for polymorphism and linkage disequilibrium (LD) based on 512 whole-genome microsatellite loci representing a mean marker density of 5.1 cM. A total of 6,724 alleles ranging from 1 to 49 per locus were identified in all collections. The mean PIC value was 0.650, ranging from 0 to 0.965. Population structure and principal coordinate analysis revealed that landraces and modern varieties were two relatively independent genetic sub-groups. Landraces had a higher allelic diversity than modern varieties with respect to both genomes and chromosomes in terms of total number of alleles and allelic richness. 3,833 (57.0%) and 2,788 (41.5%) rare alleles with frequencies of <5% were found in the landrace and modern variety gene pools, respectively, indicating greater numbers of rare variants, or likely new alleles, in landraces. Analysis of molecular variance (AMOVA) showed that A genome had the largest genetic differentiation and D genome the lowest. In contrast to genetic diversity, modern varieties displayed a wider average LD decay across the whole genome for locus pairs with r2>0.05 (P<0.001) than the landraces. Mean LD decay distance for the landraces at the whole genome level was <5 cM, while a higher LD decay distance of 5–10 cM in modern varieties. LD decay distances were also somewhat different for each of the 21 chromosomes, being higher for most of the chromosomes in modern varieties (<5∼25 cM) compared to landraces (<5∼15 cM), presumably indicating the influences of domestication and breeding. This study facilitates predicting the marker density required to effectively associate genotypes with traits in Chinese wheat genetic resources. PMID:21365016

Pro-inflammatory Cytokine Response and Genetic Diversity in Merozoite Surface Protein 2 of Plasmodium falciparum Isolates from Nigeria.

PubMed

Ajibaye, Olusola; Osuntoki, Akinniyi A; Ebuehi, Albert Ot; Iwalokun, Bamidele A; Balogun, Emmanuel O; Egbuna, Kathleen N

2017-01-01

Polymorphisms in Plasmodium falciparum merozoite surface protein-2 ( msp -2) and associated parasite genetic diversity which varies between malaria-endemic regions remain a limitation in malaria vaccine development. Pro-inflammatory cytokines are important in immunity against malaria, understanding the influence of genetic diversity on cytokine response is important for effective vaccine design. P. falciparum isolates obtained from 300 Nigerians with uncomplicated falciparum malaria at Ijede General Hospital, Ijede (IJE), General Hospital Ajeromi, Ajeromi (AJE) and Saint Kizito Mission Hospital, Lekki, were genotyped by nested polymerase chain reaction of msp -2 block 3 while ELISA was used to determine the pro-inflammatory cytokine response to describe the genetic diversity of P. falciparum . Eighteen alleles were observed for msp -2 loci. Of the 195 isolates, 61 (31.0%) had only FC27-type alleles, 38 (19.7%) had only 3D7-type alleles, and 49.3% had multiple parasite lines with both alleles. Band sizes were 275-625 bp for FC27 and 150-425 bp for 3D7. Four alleles were observed from LEK, 2 (375-425 bp) and 2 (275-325 bp) of FC27-and 3D7-types, respectively; 12 alleles from AJE, 9 (275-625 bp) and 3 (325-425 bp) of FC27-types and 3D7-types, respectively; while IJE had a total of 12 alleles, 9 (275-625 bp) and 3 (325-425 bp) of FC27-types and 3D7-types, respectively. Mean multiplicity of infection (MOI) was 1.54. Heterozygosity ( H E ) ranged from 0.77 to 0.87 and was highest for IJE (0.87). Cytokine response was higher among <5 years and was significantly associated with MOI ( P > 0.05) but with neither parasite density nor infection type. P. falciparum genetic diversity is extensive in Nigeria, protection via pro-inflammatory cytokines have little or no interplay with infection multiplicity.

Allelic recombination between distinct genomic locations generates copy number diversity in human β-defensins

PubMed Central

Bakar, Suhaili Abu; Hollox, Edward J.; Armour, John A. L.

2009-01-01

β-Defensins are small secreted antimicrobial and signaling peptides involved in the innate immune response of vertebrates. In humans, a cluster of at least 7 of these genes shows extensive copy number variation, with a diploid copy number commonly ranging between 2 and 7. Using a genetic mapping approach, we show that this cluster is at not 1 but 2 distinct genomic loci ≈5 Mb apart on chromosome band 8p23.1, contradicting the most recent genome assembly. We also demonstrate that the predominant mechanism of change in β-defensin copy number is simple allelic recombination occurring in the interval between the 2 distinct genomic loci for these genes. In 416 meiotic transmissions, we observe 3 events creating a haplotype copy number not found in the parent, equivalent to a germ-line rate of copy number change of ≈0.7% per gamete. This places it among the fastest-changing copy number variants currently known. PMID:19131514

CGG allele size somatic mosaicism and methylation in FMR1 premutation alleles

PubMed Central

Pretto, Dalyir I.; Mendoza-Morales, Guadalupe; Lo, Joyce; Cao, Ru; Hadd, Andrew; Latham, Gary J.; Durbin-Johnson, Blythe; Hagerman, Randi; Tassone, Flora

2014-01-01

Background Greater than 200 CGG repeats in the 5′UTR of the FMR1 gene leads to epigenetic silencing and lack of the FMR1 protein, causing Fragile X Syndrome. Individuals carriers of a premutation (PM) allele with 55–200 CGG repeats are typically unmethylated and can present with clinical features defined as FMR1 associated conditions. Methods Blood samples from 17 male PM carriers were assessed clinically and molecularly by Southern Blot, Western Blot, PCR and QRT-PCR. Blood and brain tissue from additional 18 PM males were also similarly examined. Continuous outcomes were modeled using linear regression and binary outcomes were modeled using logistic regression. Results Methylated alleles were detected in different fractions of blood cells in all PM cases (n= 17). CGG repeat numbers correlated with percent of methylation and mRNA levels and, especially in the upper PM range, with greater number of clinical involvements. Inter/intra- tissue somatic instability and differences in percent methylation were observed between blood and fibroblasts (n=4) and also observed between blood and different brain regions in three of the 18 premutation cases examined. CGG repeat lengths in lymphocytes remained unchanged over a period of time ranging from 2–6 years, three cases for whom multiple samples were available. Conclusion In addition to CGG size instability, individuals with a PM expanded alleles can exhibit methylation and display more clinical features likely due to RNA toxicity and/or FMR1 silencing. The observed association between CGG repeat length and percent of methylation with the severity of the clinical phenotypes underscores the potential value of methylation in affected PM to further understand penetrance, inform diagnosis and to expand treatment options. PMID:24591415

The Length Distribution of Class I-Restricted T Cell Epitopes Is Determined by Both Peptide Supply and MHC Allele-Specific Binding Preference.

PubMed

Trolle, Thomas; McMurtrey, Curtis P; Sidney, John; Bardet, Wilfried; Osborn, Sean C; Kaever, Thomas; Sette, Alessandro; Hildebrand, William H; Nielsen, Morten; Peters, Bjoern

2016-02-15

HLA class I-binding predictions are widely used to identify candidate peptide targets of human CD8(+) T cell responses. Many such approaches focus exclusively on a limited range of peptide lengths, typically 9 aa and sometimes 9-10 aa, despite multiple examples of dominant epitopes of other lengths. In this study, we examined whether epitope predictions can be improved by incorporating the natural length distribution of HLA class I ligands. We found that, although different HLA alleles have diverse length-binding preferences, the length profiles of ligands that are naturally presented by these alleles are much more homogeneous. We hypothesized that this is due to a defined length profile of peptides available for HLA binding in the endoplasmic reticulum. Based on this, we created a model of HLA allele-specific ligand length profiles and demonstrate how this model, in combination with HLA-binding predictions, greatly improves comprehensive identification of CD8(+) T cell epitopes. Copyright © 2016 by The American Association of Immunologists, Inc.

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras.

PubMed

Lopez, Ana Cecilia; Ortiz, Andres; Coello, Jorge; Sosa-Ochoa, Wilfredo; Torres, Rosa E Mejia; Banegas, Engels I; Jovel, Irina; Fontecha, Gustavo A

2012-11-26

Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite's circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission.

Delimiting Allelic Imbalance of TYMS by Allele-Specific Analysis.

PubMed

Balboa-Beltrán, Emilia; Cruz, Raquel; Carracedo, Angel; Barros, Francisco

2015-07-01

Allelic imbalance of thymidylate synthase (TYMS) is attributed to polymorphisms in the 5'- and 3'-untranslated region (UTR). These polymorphisms have been related to the risk of suffering different cancers, for example leukemia, breast or gastric cancer, and response to different drugs, among which are methotrexate glutamates, stavudine, and specifically 5-fluorouracil (5-FU), as TYMS is its direct target. A vast literature has been published in relation to 5-FU, even suggesting the sole use of these polymorphisms to effectively manage 5-FU dosage. Estimates of the extent to which these polymorphisms influence in TYMS expression have in the past been based on functional analysis by luciferase assays and quantification of TYMS mRNA, but both these studies, as the association studies with cancer risk or with toxicity or response to 5-FU, are very contradictory. Regarding functional assays, the artificial genetic environment created in luciferase assay and the problems derived from quantitative polymerase chain reactions (qPCRs), for example the use of a reference gene, may have distorted the results. To avoid these sources of interference, we have analyzed the allelic imbalance of TYMS by allelic-specific analysis in peripheral blood mononuclear cells (PBMCs) from patients.Allelic imbalance in PBMCs, taken from 40 patients with suspected myeloproliferative haematological diseases, was determined by fluorescent fragment analysis (for the 3'-UTR polymorphism), Sanger sequencing and allelic-specific qPCR in multiplex (for the 5'-UTR polymorphisms).For neither the 3'- nor the 5'-UTR polymorphisms did the observed allelic imbalance exceed 1.5 fold. None of the TYMS polymorphisms is statistically associated with allelic imbalance.The results acquired allow us to deny the previously established assertion of an influence of 2 to 4 fold of the rs45445694 and rs2853542 polymorphisms in the expression of TYMS and narrow its allelic imbalance to 1.5 fold, in our population

Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2

PubMed Central

Chan, Elizabeth A. W.; Teng, Grace; Corbett, Elizabeth; Choudhury, Kingshuk Roy; Bassing, Craig H.; Schatz, David G.; Krangel, Michael S.

2013-01-01

Allelic exclusion requires that the two alleles at antigen-receptor loci attempt to recombine variable (V), diversity (D), and joining (J) gene segments [V(D)J recombination] asynchronously in nuclei of developing lymphocytes. It previously was shown that T-cell receptor β (Tcrb) alleles frequently and stochastically associate with the nuclear lamina and pericentromeric heterochromatin in CD4−CD8− thymocytes. Moreover, rearranged alleles were underrepresented at these locations. Here we used 3D immunofluorescence in situ hybridization to identify recently rearranged Tcrb alleles based on the accumulation of the DNA-repair protein 53BP1. We found that Tcrb alleles recombine asynchronously in double-negative thymocytes and that V(D)J recombination is suppressed on peripheral as compared with central Tcrb alleles. Moreover, the recombination events that did take place at the nuclear periphery preferentially occurred on Tcrb alleles that were partially dissociated from the nuclear lamina. To understand better the mechanism by which V(D)J recombination is suppressed at the nuclear periphery, we evaluated the subnuclear distribution of recombination-activating gene 2 (RAG2) protein. We found that RAG2 abundance was reduced at the nuclear periphery. Moreover, RAG2 was distributed differently from RNA polymerase II and histone H3K4 trimethylation. Our data suggest that the nuclear periphery suppresses V(D)J recombination, at least in part, by segregating Tcrb alleles from RAG proteins. PMID:24218622

Population genetic diversity and fitness in multiple environments

EPA Science Inventory

When a large number of alleles are lost from a population, increases in homozygosity may reduce individual fitness through inbreeding depression. Modest losses of allelic diversity may also negatively impact long-term population viability by reducing the capacity of populations t...

Trends in genome-wide and region-specific genetic diversity in the Dutch-Flemish Holstein-Friesian breeding program from 1986 to 2015.

PubMed

Doekes, Harmen P; Veerkamp, Roel F; Bijma, Piter; Hiemstra, Sipke J; Windig, Jack J

2018-04-11

In recent decades, Holstein-Friesian (HF) selection schemes have undergone profound changes, including the introduction of optimal contribution selection (OCS; around 2000), a major shift in breeding goal composition (around 2000) and the implementation of genomic selection (GS; around 2010). These changes are expected to have influenced genetic diversity trends. Our aim was to evaluate genome-wide and region-specific diversity in HF artificial insemination (AI) bulls in the Dutch-Flemish breeding program from 1986 to 2015. Pedigree and genotype data (~ 75.5 k) of 6280 AI-bulls were used to estimate rates of genome-wide inbreeding and kinship and corresponding effective population sizes. Region-specific inbreeding trends were evaluated using regions of homozygosity (ROH). Changes in observed allele frequencies were compared to those expected under pure drift to identify putative regions under selection. We also investigated the direction of changes in allele frequency over time. Effective population size estimates for the 1986-2015 period ranged from 69 to 102. Two major breakpoints were observed in genome-wide inbreeding and kinship trends. Around 2000, inbreeding and kinship levels temporarily dropped. From 2010 onwards, they steeply increased, with pedigree-based, ROH-based and marker-based inbreeding rates as high as 1.8, 2.1 and 2.8% per generation, respectively. Accumulation of inbreeding varied substantially across the genome. A considerable fraction of markers showed changes in allele frequency that were greater than expected under pure drift. Putative selected regions harboured many quantitative trait loci (QTL) associated to a wide range of traits. In consecutive 5-year periods, allele frequencies changed more often in the same direction than in opposite directions, except when comparing the 1996-2000 and 2001-2005 periods. Genome-wide and region-specific diversity trends reflect major changes in the Dutch-Flemish HF breeding program. Introduction of

Natural selection on marine carnivores elaborated a diverse family of classical MHC class I genes exhibiting haplotypic gene content variation and allelic polymorphism

PubMed Central

Norman, Paul J.; Parham, Peter

2012-01-01

Pinnipeds, marine carnivores, diverged from terrestrial carnivores ~45 million years ago, before their adaptation to marine environments. This lifestyle change exposed pinnipeds to different microbiota and pathogens, with probable impact on their MHC class I genes. Investigating this question, genomic sequences were determined for 71 MHC class I variants: 27 from harbor seal and 44 from gray seal. These variants form three MHC class I gene lineages, one comprising a pseudogene. The second, a candidate nonclassical MHC class I gene, comprises a nonpolymorphic transcribed gene related to dog DLA-79 and giant panda Aime-1906. The third is the diversity lineage, which includes 62 of the 71 seal MHC class I variants. All are transcribed, and they minimally represent six harbor and 12 gray seal MHC class I genes. Besides species-specific differences in gene number, seal MHC class I haplotypes exhibit gene content variation and allelic polymorphism. Patterns of sequence variation, and of positions for positively selected sites, indicate the diversity lineage genes are the seals’ classical MHC class I genes. Evidence that expansion of diversity lineage genes began before gray and harbor seals diverged is the presence in both species of two distinctive sublineages of diversity lineage genes. Pointing to further expansion following the divergence are the presence of species-specific genes and greater MHC class I diversity in gray seals than harbor seals. The elaboration of a complex variable family of classical MHC class I genes in pinnipeds contrasts with the single, highly polymorphic classical MHC class I gene of dog and giant panda, terrestrial carnivores. PMID:23001684

Reciprocal translocation of small numbers of inbred individuals rescues immunogenetic diversity.

PubMed

Grueber, Catherine E; Sutton, Jolene T; Heber, Sol; Briskie, James V; Jamieson, Ian G; Robertson, Bruce C

2017-05-01

Genetic rescue can reduce inbreeding depression and increase fitness of small populations, even when the donor populations are highly inbred. In a recent experiment involving two inbred island populations of the New Zealand South Island robin, Petroica australis, reciprocal translocations improved microsatellite diversity and individual fitness. While microsatellite loci may reflect patterns of genome-wide diversity, they generally do not indicate the specific genetic regions responsible for increased fitness. We tested the effectiveness of this reciprocal translocation for rescuing diversity of two immunogenetic regions: Toll-like receptor (TLR) and major histocompatibility complex (MHC) genes. We found that the relatively small number of migrants (seven and ten per island) effectively brought the characteristic TLR gene diversity of each source population into the recipient population. However, when migrants transmitted TLR alleles that were already present at high frequency in the recipient population, it was possible for offspring of mixed heritage to have decreased gene diversity compared to recipient population diversity prior to translocation. In contrast to TLRs, we did not observe substantial changes in MHC allelic diversity following translocation, with limited evidence of a decrease in differentiation, perhaps because most MHC alleles were observed at both sites prior to the translocation. Overall, we conclude that small numbers of migrants may successfully restore the diversity of immunogenetic loci with few alleles, but that translocating larger numbers of animals would provide additional opportunity for the genetic rescue of highly polymorphic immunity regions, such as the MHC, even when the source population is inbred. © 2017 John Wiley & Sons Ltd.

Population Genetic Diversity and Fitness in Multiple Environments(BMCEB)

EPA Science Inventory

When a large number of alleles are lost from a population, increases in individual homozygosity may reduce individual fitness through inbreeding depression. Modest losses of allelic diversity may also negatively impact long-term population viability by reducing the capacity of p...

Impact of alternative regeneration methods on genetic diversity in coastal Douglas-fir

USGS Publications Warehouse

Adams, W.T.; Zuo, J.; Shimizu, J.Y.; Tappeiner, J. C.

1998-01-01

Genetic implications of natural and artificial regeneration following three regeneration methods (group selection, shelterwood, and clearcut) were investigated in coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) using genetic markers (17 allozyme loci). In general, harvesting followed by either natural or artificial regeneration resulted in offspring populations little altered from those in the previous generation. Cutting the smallest trees to form shelterwoods, however, resulted in the removal of rare, presumably deleterious, alleles, such that slightly fewer alleles per locus were observed among residual trees (2.76) and natural regeneration (2.75) than found in uncut (control) stands (2.86). Thus, although the shelterwood regime appears quite compatible with gene conservation, it would be best to leave parent trees of a range of sizes in shelterwoods designated as gene conservation reserves, in order to maximize the number of alleles (regardless of current adaptive value) in naturally regenerated offspring. Seedling stocks used for artificial regeneration in clearcut, shelterwood, and group selection stands (7 total) had significantly greater levels of genetic diversity, on average, than found in natural regeneration. This is probably because the seeds used in artificial seedling stocks came from many wild stands and thus, sampled more diversity than found in single populations. For. Sci. 44(3): 390-396.

A wild origin of the loss-of-function lycopene beta cyclase (CYC-b) allele in cultivated, red-fleshed papaya (Carica papaya).

PubMed

Wu, Meng; Lewis, Jamicia; Moore, Richard C

2017-01-01

The red flesh of some papaya cultivars is caused by a recessive loss-of-function mutation in the coding region of the chromoplast-specific lycopene beta cyclase gene (CYC-b). We performed an evolutionary genetic analysis of the CYC-b locus in wild and cultivated papaya to uncover the origin of this loss-of-function allele in cultivated papaya. We analyzed the levels and patterns of genetic diversity at the CYC-b locus and six loci in a 100-kb region flanking CYC-b and compared these to genetic diversity levels at neutral autosomal loci. The evolutionary relationships of CYC-b haplotypes were assessed using haplotype network analysis of the CYC-b locus and the 100-kb CYC-b region. Genetic diversity at the recessive CYC-b allele (y) was much lower relative to the dominant Y allele found in yellow-fleshed wild and cultivated papaya due to a strong selective sweep. Haplotype network analyses suggest the y allele most likely arose in the wild and was introduced into domesticated varieties after the first papaya domestication event. The shared haplotype structure between some wild, feral, and cultivated haplotypes around the y allele supports subsequent escape of this allele from red cultivars back into wild populations through feral intermediates. Our study supports a protracted domestication process of papaya through the introgression of wild-derived traits and gene flow from cultivars to wild populations. Evidence of gene flow from cultivars to wild populations through feral intermediates has implications for the introduction of transgenic papaya into Central American countries. © 2017 Botanical Society of America.

Genetic diversity of Plasmodium vivax and Plasmodium falciparum in Honduras

PubMed Central

2012-01-01

Background Understanding the population structure of Plasmodium species through genetic diversity studies can assist in the design of more effective malaria control strategies, particularly in vaccine development. Central America is an area where malaria is a public health problem, but little is known about the genetic diversity of the parasite’s circulating species. This study aimed to investigate the allelic frequency and molecular diversity of five surface antigens in field isolates from Honduras. Methods Five molecular markers were analysed to determine the genotypes of Plasmodium vivax and Plasmodium falciparum from endemic areas in Honduras. Genetic diversity of ama-1, msp-1 and csp was investigated for P. vivax, and msp-1 and msp-2 for P. falciparum. Allelic frequencies were calculated and sequence analysis performed. Results and conclusion A high genetic diversity was observed within Plasmodium isolates from Honduras. A different number of genotypes were elucidated: 41 (n = 77) for pvama-1; 23 (n = 84) for pvcsp; and 23 (n = 35) for pfmsp-1. Pvcsp sequences showed VK210 as the only subtype present in Honduran isolates. Pvmsp-1 (F2) was the most polymorphic marker for P. vivax isolates while pvama-1 was least variable. All three allelic families described for pfmsp-1 (n = 30) block 2 (K1, MAD20, and RO33), and both allelic families described for the central domain of pfmsp-2 (n = 11) (3D7 and FC27) were detected. However, K1 and 3D7 allelic families were predominant. All markers were randomly distributed across the country and no geographic correlation was found. To date, this is the most complete report on molecular characterization of P. vivax and P. falciparum field isolates in Honduras with regards to genetic diversity. These results indicate that P. vivax and P. falciparum parasite populations are highly diverse in Honduras despite the low level of transmission. PMID:23181845

The Diversity Outbred Mouse Population

PubMed Central

Churchill, Gary A.; Gatti, Daniel M.; Munger, Steven C.; Svenson, Karen L.

2012-01-01

The Diversity Outbred (DO) population is a heterogeneous stock derived from the same eight founder strains as the Collaborative Cross (CC) inbred strains. Genetically heterogeneous DO mice display a broad range of phenotypes. Natural levels of heterozygosity provide genetic buffering and, as a result, DO mice are robust and breed well. Genetic mapping analysis in the DO presents new challenges and opportunities. Specialized algorithms are required to reconstruct haplotypes from high-density SNP array data. The eight founder haplotypes can be combined into 36 possible diplotypes, which must be accommodated in QTL mapping analysis. Population structure of the DO must be taken into account here. Estimated allele effects of 8 founder haplotypes provide information that is not available in two-parent crosses and can dramatically reduce the number of candidate loci. Allele effects can also distinguish chance co-location of QTL from pleiotropy – which provides a basis for establishing causality in expression QTL studies. We recommended sample sizes of 200 to 800 mice for QTL mapping studies, larger than for traditional crosses. The CC inbred strains provide a resource for independent validation of DO mapping results. Genetic heterogeneity of the DO can provide a powerful advantage in our ability to generalize conclusions to other genetically diverse populations. Genetic diversity can also help to avoid the pitfall of identifying an idiosyncratic reaction that occurs only in a limited genetic context. Informatics tools and data resources associated with the CC, the DO, and their founder strains are developing rapidly. We anticipate a flood of new results to follow as our community begins to adopt and utilize these new genetic resource populations. PMID:22892839

Diversity and host range of foliar fungal endophytes: are tropical leaves biodiversity hotspots?

PubMed

Arnold, A Elizabeth; Lutzoni, F

2007-03-01

Fungal endophytes are found in asymptomatic photosynthetic tissues of all major lineages of land plants. The ubiquity of these cryptic symbionts is clear, but the scale of their diversity, host range, and geographic distributions are unknown. To explore the putative hyperdiversity of tropical leaf endophytes, we compared endophyte communities along a broad latitudinal gradient from the Canadian arctic to the lowland tropical forest of central Panama. Here, we use molecular sequence data from 1403 endophyte strains to show that endophytes increase in incidence, diversity, and host breadth from arctic to tropical sites. Endophyte communities from higher latitudes are characterized by relatively few species from many different classes of Ascomycota, whereas tropical endophyte assemblages are dominated by a small number of classes with a very large number of endophytic species. The most easily cultivated endophytes from tropical plants have wide host ranges, but communities are dominated by a large number of rare species whose host range is unclear. Even when only the most easily cultured species are considered, leaves of tropical trees represent hotspots of fungal species diversity, containing numerous species not yet recovered from other biomes. The challenge remains to recover and identify those elusive and rarely cultured taxa with narrower host ranges, and to elucidate the ecological roles of these little-known symbionts in tropical forests.

[Genetic diversity of modern Russian durum wheat cultivars at the gliadin-coding loci].

PubMed

Kudriavtsev, A M; Dedova, L V; Mel'nik, V A; Shishkina, A A; Upelniek, V P; Novosel'skaia-Dragovich, A Iu

2014-05-01

The allelic diversity at four gliadin-coding loci was examined in modern cultivars of the spring and winter durum wheat Triticum durum Desf. Comparative analysis of the allelic diversity showed that the gene pools of these two types of durum wheat, having different life styles, were considerably different. For the modern spring durum wheat cultivars, a certain reduction of the genetic diversity was observed compared to the cultivars bred in the 20th century.

A conditional allele of Rspo3 reveals redundant function of R-spondins during mouse limb development.

PubMed

Neufeld, Stanley; Rosin, Jessica M; Ambasta, Anshula; Hui, Kristen; Shaneman, Venessa; Crowder, Ray; Vickerman, Lori; Cobb, John

2012-10-01

R-spondins are secreted ligands that bind cell surface receptors and activate Wnt/β-catenin signaling. Human mutations and gene inactivation studies in mice have revealed a role for these four proteins (RSPO1-4) in diverse developmental processes ranging from sex determination to limb development. Among the genes coding for R-spondins, only inactivation of Rspo3 shows early embryonic lethality (E10.5 in mice). Therefore, a conditional allele of this gene is necessary to understand the function of R-spondins throughout murine development. To address this need, we have produced an allele in which loxP sites flank exons 2-4 of Rspo3, allowing tissue-specific deletion of these exons in the presence of Cre recombinase. We used these mice to investigate the role of Rspo3 during limb development and found that limbs ultimately developed normally in the absence of Rspo3 function. However, severe hindlimb truncations resulted when Rspo3 and Rspo2 mutations were combined, demonstrating redundant function of these genes. Copyright © 2012 Wiley Periodicals, Inc.

Plasmodium vivax merozoite surface protein-3 alpha: a high-resolution marker for genetic diversity studies.

PubMed

Prajapati, Surendra Kumar; Joshi, Hema; Valecha, Neena

2010-06-01

Malaria, an ancient human infectious disease caused by five species of Plasmodium, among them Plasmodium vivax is the most widespread human malaria species and causes huge morbidity to its host. Identification of genetic marker to resolve higher genetic diversity for an ancient origin organism is a crucial task. We have analyzed genetic diversity of P. vivax field isolates using highly polymorphic antigen gene merozoite surface protein-3 alpha (msp-3 alpha) and assessed its suitability as high-resolution genetic marker for population genetic studies. 27 P. vivax field isolates collected during chloroquine therapeutic efficacy study at Chennai were analyzed for genetic diversity. PCR-RFLP was employed to assess the genetic variations using highly polymorphic antigen gene msp-3 alpha. We observed three distinct PCR alleles at msp-3 alpha, and among them allele A showed significantly high frequency (53%, chi2 = 8.22, p = 0.001). PCR-RFLP analysis revealed 14 and 17 distinct RFLP patterns for Hha1 and Alu1 enzymes respectively. Further, RFLP analysis revealed that allele A at msp-3 alpha is more diverse in the population compared with allele B and C. Combining Hha1 and Alu1 RFLP patterns revealed 21 distinct genotypes among 22 isolates reflects higher diversity resolution power of msp-3 alpha in the field isolates. P. vivax isolates from Chennai region revealed substantial amount of genetic diversity and comparison of allelic diversity with other antigen genes and microsatellites suggesting that msp-3 alpha could be a high-resolution marker for genetic diversity studies among P. vivax field isolates.

HLA-DQA1 and HLA-DQB1 allele diversity and its extended haplotypes in Madeira Island (Portugal).

PubMed

Spínola, H; Lemos, A; Couto, A R; Parreira, B; Soares, M; Dutra, I; Bruges-Armas, J; Brehm, A

2017-02-01

This study shows, for the first time, high-resolution allele frequencies of HLA-DQA1 loci in Madeira Island (Portugal) and allows us to better understand and refine present knowledge on DQB1 variation, with the identification of several alleles not previously reported in this population. Estimates on haplotype profile, involving HLA-A, HLA-B, HLA-DRB1, HLA-DQA1 and HLA-DQB1, are also reported. © 2016 John Wiley & Sons Ltd.

Genetic diversity and population structure of an insular tree, Santalum austrocaledonicum in New Caledonian archipelago.

PubMed

Bottin, L; Verhaegen, D; Tassin, J; Olivieri, I; Vaillant, A; Bouvet, J M

2005-06-01

We present a study of the genetic diversity and structure of a tropical tree in an insular system. Santalum austrocaledonicum is endemic to the archipelago of New Caledonia and is exploited for oil extraction from heartwood. A total of 431 individuals over 17 populations were analysed for eight polymorphic microsatellite loci. The number of alleles per locus ranged from 3 to 33 and the observed heterozygosity per population ranged from 0.01 in Mare to 0.74 in Ile des Pins. The genetic diversity was lowest in the most recent islands, the Loyautes, and highest in the oldest island, Grande Terre, as well as the nearby small Ile des Pins. Significant departures from panmixia were observed for some loci-population combinations (per population FIS = 0-0.03 on Grande-Terre and Ile des Pins, and 0-0.67 on Loyautes). A strong genetic differentiation among all islands was observed (FST = 0.22), and the amount of differentiation increased with geographic distance in Iles Loyaute and in Grande Terre. At both population and island levels, island age and isolation seem to be the main factors influencing the amount of genetic diversity. In particular, populations from recent islands had large average FIS that could not be entirely explained by null alleles or a Wahlund effect. This result suggests that, at least in some populations, selfing occurred extensively. Conclusively, our results indicate a strong influence of insularity on the genetic diversity and structure of Santalum austrocaledonicum.

Alleles conferring improved fiber quality from EMS mutagenesis of elite cotton genotypes

USDA-ARS?s Scientific Manuscript database

The elite gene pool of cotton (Gossypium spp.) has less diversity than those of most other major crops, making identification of novel alleles important to ongoing crop improvement. A total of 3,164 M5 lines resulting from ethyl methanesulfonate mutagenesis of two G. hirsutum breeding lines, TAM 94L...

Multiple introductions boosted genetic diversity in the invasive range of black cherry (Prunus serotina; Rosaceae)

PubMed Central

Pairon, Marie; Petitpierre, Blaise; Campbell, Michael; Guisan, Antoine; Broennimann, Olivier; Baret, Philippe V.; Jacquemart, Anne-Laure; Besnard, Guillaume

2010-01-01

Background and Aims Black cherry (Prunus serotina) is a North American tree that is rapidly invading European forests. This species was introduced first as an ornamental plant then it was massively planted by foresters in many countries but its origins and the process of invasion remain poorly documented. Based on a genetic survey of both native and invasive ranges, the invasion history of black cherry was investigated by identifying putative source populations and then assessing the importance of multiple introductions on the maintenance of gene diversity. Methods Genetic variability and structure of 23 populations from the invasive range and 22 populations from the native range were analysed using eight nuclear microsatellite loci and five chloroplast DNA regions. Key Results Chloroplast DNA diversity suggests there were multiple introductions from a single geographic region (the north-eastern United States). A low reduction of genetic diversity was observed in the invasive range for both nuclear and plastid genomes. High propagule pressure including both the size and number of introductions shaped the genetic structure in Europe and boosted genetic diversity. Populations from Denmark, The Netherlands, Belgium and Germany showed high genetic diversity and low differentiation among populations, supporting the hypothesis that numerous introduction events, including multiple individuals and exchanges between sites, have taken place during two centuries of plantation. Conclusions This study postulates that the invasive black cherry has originated from east of the Appalachian Mountains (mainly the Allegheny plateau) and its invasiveness in north-western Europe is mainly due to multiple introductions containing high numbers of individuals. PMID:20400456

Assessment of genetic diversity of Tunisian orange, Citrus sinensis (L.) Osbeck using microsatellite (SSR) markers.

PubMed

Mahjbi, A; Oueslati, A; Baraket, G; Salhi-Hannachi, A; Zehdi Azouzi, S

2016-05-20

Citrus are one of the most cultivated crops in the world. Economically, they are very important fruit trees in Tunisia. Little is known about the genetic diversity of the Tunisian Citrus germplasm. Exploring this diversity is a prerequisite for the identification and characterization of the local germplasm to circumvent and controlling genetic erosion caused by biotic and abiotic stress to aid its conservation and use. In the present study, we explored the genetic diversity of 20 Tunisian orange cultivars [Citrus sinensis (L.) Osbeck] and established their relationships by using seven simple sequence repeat (SSR) loci. In total, 37 alleles and 44 genotypes were scored. The sizes of alleles ranged from 90 to 280 bp. The number of alleles per locus was from 4 to 7, with an average of 5.28. Polymorphic information content value changed from 0.599 to 0.769 with an average of 0.675. Analysis of the genotypes revealed a heterozygote deficiency across all the genotypes. The observed heterozygosity varied from 0 to 1 (average of 0.671). Cluster analysis showed that three groups could be distinguished and the polymorphism occurred independently of the geographical origin of the studied orange cultivars. The detected SSR genotypes allowed the establishment of an identification key with a discriminating power of 100%. Multivariate analysis and the neighbor-joining phylogenetic tree indicated a narrow genetic base for the orange cultivars. The usefulness of SSR markers for orange fingerprinting and evaluation of the genetic diversity in the Tunisian germplasm are discussed in this paper.

A genetically diverse but distinct North American population of Sarcocystis neurona includes an overrepresented clone described by 12 microsatellite alleles.

PubMed

Asmundsson, Ingrid M; Dubey, J P; Rosenthal, Benjamin M

2006-09-01

The population genetics and systematics of most coccidians remain poorly defined despite their impact on human and veterinary health. Non-recombinant parasite clones characterized by distinct transmission and pathogenesis traits persist in the coccidian Toxoplasma gondii despite opportunities for sexual recombination. In order to determine whether this may be generally true for tissue-cyst forming coccidia, and to address evolutionary and taxonomic problems within the genus Sarcocystis, we characterized polymorphic microsatellite markers in Sarcocystis neurona, the major causative agent of equine protozoal myeloencephalitis (EPM). Bayesian statistical modeling, phylogenetic reconstruction based on genotypic chord distances, and analyses of linkage disequilibrium were employed to examine the population structure within S. neurona and closely related Sarcocystis falcatula isolates from North and South America. North American S. neurona were clearly differentiated from those of South America and also from isolates of S. falcatula. Although S. neurona is characterized by substantial allelic and genotypic diversity typical of interbreeding populations, one genotype occurs with significantly excessive frequency; thus, some degree of asexual propagation of S. neurona clones may naturally occur. Finally, S. neurona isolated from disparate North American localities and diverse hosts (opossums, a Southern sea otter, and horses) comprise a single genetic population. Isolates associated with clinical neurological disease bear no obvious distinction as measured by these presumably neutral genetic markers.

Whole genome sequencing of Oryza sativa L. cv. Seeragasamba identifies a new fragrance allele in rice

PubMed Central

Bindusree, Ganigara; Natarajan, Purushothaman; Kalva, Sukesh

2017-01-01

Fragrance of rice is an important trait that confers a large economic benefit to the farmers who cultivate aromatic rice varieties. Several aromatic rice varieties have limited geographic distribution, and are endowed with variety-specific unique fragrances. BADH2 was identified as a fragrance gene in 2005, and it is essential to identify the fragrance alleles from diverse geographical locations and genetic backgrounds. Seeragasamba is a short-grain aromatic rice variety of the indica type, which is cultivated in a limited area in India. Whole genome sequencing of this variety identified a new badh2 allele (badh2-p) with an 8 bp insertion in the promoter region of the BADH2 gene. When the whole genome sequences of 76 aromatic varieties in the 3000 rice genome project were analyzed, the badh2-p allele was present in 13 varieties (approximately 17%) of both indica and japonica types. In addition, the badh2-p allele was present in 17 varieties that already had the loss-of-function allele, badh2-E7. Taken together, the frequency of badh2-p allele (approximately 40%) was found to be greater than that of the badh2-E7 allele (approximately 34%) among the aromatic rice varieties. Therefore, it is suggested to include badh2-p as a predominant allele when screening for fragrance alleles in aromatic rice varieties. PMID:29190814

An assessment of Wx microsatellite allele, alkali degradation and differentiation of chloroplast DNA in traditional black rice (Oryza sativa L.) from Thailand and Lao PDR.

PubMed

Prathepha, Preecha

2007-01-15

Thailand and Lao PDR are the country's rich rice diversity. To contribute a significant knowledge for development new rice varieties, a collection of 142 black rice (Oryza sativa) accessions were determined for variation of physico-chemical properties, Wx microsatellite allele, Wx allele and chloroplast DNA type. The results showed that amylose content of black rice accessions were ranged from 1.9 to 6.8%. All of the alkali disintegration types (high, intermediate and low) was observed in these rice with average of 1.75 on the 1-3 digestibility scale. The unique Wx microsatellite allele (CT)17 was found in these samples and all black rice strains carried Wx(b) allele. In addition, all black rice accessions were found the duplication of the 23 bp sequence motif in the exon 2 of the wx gene. This evidence is a common phenomenon in glutinous rice. Based on two growing condition for black rice, rainfed lowland and rainfed upland, chloroplast DNA type was distinct from each other. All rice strains from rainfed lowland was deletion plastotype, but all other rainfed upland strains were non-deletion types.

Coalescence and genetic diversity in sexual populations under selection.

PubMed

Neher, Richard A; Kessinger, Taylor A; Shraiman, Boris I

2013-09-24

In sexual populations, selection operates neither on the whole genome, which is repeatedly taken apart and reassembled by recombination, nor on individual alleles that are tightly linked to the chromosomal neighborhood. The resulting interference between linked alleles reduces the efficiency of selection and distorts patterns of genetic diversity. Inference of evolutionary history from diversity shaped by linked selection requires an understanding of these patterns. Here, we present a simple but powerful scaling analysis identifying the unit of selection as the genomic "linkage block" with a characteristic length, , determined in a self-consistent manner by the condition that the rate of recombination within the block is comparable to the fitness differences between different alleles of the block. We find that an asexual model with the strength of selection tuned to that of the linkage block provides an excellent description of genetic diversity and the site frequency spectra compared with computer simulations. This linkage block approximation is accurate for the entire spectrum of strength of selection and is particularly powerful in scenarios with many weakly selected loci. The latter limit allows us to characterize coalescence, genetic diversity, and the speed of adaptation in the infinitesimal model of quantitative genetics.

Always look on both sides: Phylogenetic information conveyed by simple sequence repeat allele sequences

USDA-ARS?s Scientific Manuscript database

Simple sequence repeat (SSR) markers are widely used tools for inferences about genetic diversity, phylogeography and spatial genetic structure. Their applications assume that variation among alleles is essentially caused by an expansion or contraction of the number of repeats and that, accessorily,...

Landscape-level patterns of avian diversity in the Oregon Coast Range

Treesearch

Samuel A. Cushman; Kevin McGarigal

2003-01-01

We used a comparative mensurative landscape-level experiment to quantify the relative importance of mature forest area and fragmentation and differences among watersheds in influencing avian community diversity in the Oregon Coast Range, USA. Our study design included three large hydrological basins, two levels of fragmentation, and six levels of mature forest area. We...

Patterns of genetic diversity reveal multiple introductions and recurrent founder effects during range expansion in invasive populations of Geranium carolinianum (Geraniaceae)

PubMed Central

Shirk, R Y; Hamrick, J L; Zhang, C; Qiang, S

2014-01-01

Genetic diversity, and thus the adaptive potential of invasive populations, is largely based on three factors: patterns of genetic diversity in the species' native range, the number and location of introductions and the number of founding individuals per introduction. Specifically, reductions in genetic diversity (‘founder effects') should be stronger for species with low within-population diversity in their native range and few introductions of few individuals to the invasive range. We test these predictions with Geranium carolinianum, a winter annual herb native to North America and invasive in China. We measure the extent of founder effects using allozymes and microsatellites, and ask whether this is consistent with its colonization history and patterns of diversity in the native range. In the native range, genetic diversity is higher and structure is lower than expected based on life history traits. In China, our results provide evidence for multiple introductions near Nanjing, Jiangsu province, with subsequent range expansion to the west and south. Patterns of genetic diversity across China reveal weak founder effects that are driven largely by low-diversity populations at the expansion front, away from the introduction location. This suggests that reduced diversity in China has resulted from successive founder events during range expansion, and that the loss of genetic diversity in the Nanjing area was mitigated by multiple introductions from diverse source populations. This has implications for the future of G. carolinianum in China, as continued gene flow among populations should eventually increase genetic diversity within the more recently founded populations. PMID:24346497

Analysis of genetic diversity of rapeseed genetic resources in Japan and core collection construction

PubMed Central

Chen, Ruikun; Hara, Takashi; Ohsawa, Ryo; Yoshioka, Yosuke

2017-01-01

Diversity analysis of rapeseed accessions preserved in the Japanese Genebank can provide valuable information for breeding programs. In this study, 582 accessions were genotyped with 30 SSR markers covering all 19 rapeseed chromosomes. These markers amplified 311 alleles (10.37 alleles per marker; range, 3–39). The genetic diversity of Japanese accessions was lower than that of overseas accessions. Analysis of molecular variance indicated significant genetic differentiation between Japanese and overseas accessions. Small but significant differences were found among geographical groups in Japan, and genetic differentiation tended to increase with geographical distance. STRUCTURE analysis indicated the presence of two main genetic clusters in the NARO rapeseed collection. With the membership probabilities threshold, 227 accessions mostly originating from overseas were assigned to one subgroup, and 276 accessions mostly originating from Japan were assigned to the other subgroup. The remaining 79 accessions are assigned to admixed group. The core collection constructed comprises 96 accessions of diverse origin. It represents the whole collection well and thus it may be useful for rapeseed genetic research and breeding programs. The core collection improves the efficiency of management, evaluation, and utilization of genetic resources. PMID:28744177

Relationships among walleye population characteristics and genetic diversity in northern Wisconsin Lakes

USGS Publications Warehouse

Waterhouse, Matthew D.; Sloss, Brian L.; Isermann, Daniel A.

2014-01-01

The maintenance of genetic integrity is an important goal of fisheries management, yet little is known regarding the effects of management actions (e.g., stocking, harvest regulations) on the genetic diversity of many important fish species. Furthermore, relationships between population characteristics and genetic diversity remain poorly understood. We examined relationships among population demographics (abundance, recruitment, sex ratio, and mean age of the breeding population), stocking intensity, and genetic characteristics (heterozygosity, effective number of alleles, allelic richness, Wright's inbreeding coefficient, effective population size [Ne], mean d2 [a measure of inbreeding], mean relatedness, and pairwise population ΦST estimates) for 15 populations of Walleye Sander vitreus in northern Wisconsin. We also tested for potential demographic and genetic influences on Walleye body condition and early growth. Combinations of demographic variables explained 47.1–79.8% of the variation in genetic diversity. Skewed sex ratios contributed to a reduction in Ne and subsequent increases in genetic drift and relatedness among individuals within populations; these factors were correlated to reductions in allelic richness and early growth rate. Levels of inbreeding were negatively related to both age-0 abundance and mean age, suggesting Ne was influenced by recruitment and generational overlap. A negative relationship between the effective number of alleles and body condition suggests stocking affected underlying genetic diversity of recipient populations and the overall productivity of the population. These relationships may result from poor performance of stocked fish, outbreeding depression, or density-dependent factors. An isolation-by-distance pattern of genetic diversity was apparent in nonstocked populations, but was disrupted in stocked populations, suggesting that stocking affected genetic structure. Overall, demographic factors were related to genetic

Changing geographic ranges of ticks and tick-borne pathogens: drivers, mechanisms and consequences for pathogen diversity

PubMed Central

Ogden, Nick H.; Mechai, Samir; Margos, Gabriele

2013-01-01

The geographic ranges of ticks and tick-borne pathogens are changing due to global and local environmental (including climatic) changes. In this review we explore current knowledge of the drivers for changes in the ranges of ticks and tick-borne pathogen species and strains via effects on their basic reproduction number (R0), and the mechanisms of dispersal that allow ticks and tick-borne pathogens to invade suitable environments. Using the expanding geographic distribution of the vectors and agent of Lyme disease as an example we then investigate what could be expected of the diversity of tick-borne pathogens during the process of range expansion, and compare this with what is currently being observed. Lastly we explore how historic population and range expansions and contractions could be reflected in the phylogeography of ticks and tick-borne pathogens seen in recent years, and conclude that combined study of currently changing tick and tick-borne pathogen ranges and diversity, with phylogeographic analysis, may help us better predict future patterns of invasion and diversity. PMID:24010124

Changing geographic ranges of ticks and tick-borne pathogens: drivers, mechanisms and consequences for pathogen diversity.

PubMed

Ogden, Nick H; Mechai, Samir; Margos, Gabriele

2013-01-01

The geographic ranges of ticks and tick-borne pathogens are changing due to global and local environmental (including climatic) changes. In this review we explore current knowledge of the drivers for changes in the ranges of ticks and tick-borne pathogen species and strains via effects on their basic reproduction number (R 0), and the mechanisms of dispersal that allow ticks and tick-borne pathogens to invade suitable environments. Using the expanding geographic distribution of the vectors and agent of Lyme disease as an example we then investigate what could be expected of the diversity of tick-borne pathogens during the process of range expansion, and compare this with what is currently being observed. Lastly we explore how historic population and range expansions and contractions could be reflected in the phylogeography of ticks and tick-borne pathogens seen in recent years, and conclude that combined study of currently changing tick and tick-borne pathogen ranges and diversity, with phylogeographic analysis, may help us better predict future patterns of invasion and diversity.

Identification of the third/extra allele for forensic application in cases with TPOX tri-allelic pattern.

PubMed

Picanço, Juliane Bentes; Raimann, Paulo Eduardo; Motta, Carlos Henrique Ares Silveira da; Rodenbusch, Rodrigo; Gusmão, Leonor; Alho, Clarice Sampaio

2015-05-01

Genotyping of polymorphic short tandem repeats (STRs) loci is widely used in forensic DNA analysis. STR loci eventually present tri-allelic pattern as a genotyping irregularity and, in that situation, the doubt about the tri-allele locus frequency calculation can reduce the analysis strength. In the TPOX human STR locus, tri-allelic genotypes have been reported with a widely varied frequency among human populations. We investigate whether there is a single extra allele (the third allele) in the TPOX tri-allelic pattern, what it is, and where it is, aiming to understand its genomic anatomy and to propose the knowledge of this TPOX extra allele from genetic profile, thus preserving the two standard TPOX alleles in forensic analyses. We looked for TPOX tri-allelic subjects in 75,113 Brazilian families. Considering only the parental generation (mother+father) we had 150,226 unrelated subjects evaluated. From this total, we found 88 unrelated subjects with tri-allelic pattern in the TPOX locus (0.06%; 88/150,226). Seventy three of these 88 subjects (73/88; 83%) had the Clayton's original Type 2 tri-allelic pattern (three peaks of even intensity). The remaining 17% (15/88) show a new Type 2 derived category with heterozygote peak imbalance (one double dose peak plus one regular sized peak). In this paper we present detailed data from 66 trios (mother+father+child) with true biological relationships. In 39 of these families (39/66; 59%) the extra TPOX allele was transmitted either from the mother or from the father to the child. Evidences indicated the allele 10 as the extra TPOX allele, and it is on the X chromosome. The present data, which support the previous Lane hypothesis, improve the knowledge about tri-allelic pattern of TPOX CODIS' locus allowing the use of TPOX profile in forensic analyses even when with tri-allelic pattern. This evaluation is now available for different forensic applications. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Population structure and genetic diversity of the amphiatlantic haploid peatmoss Sphagnum affine (Sphagnopsida).

PubMed

Thingsgaard, K

2001-10-01

Nineteen populations of Sphagnum affine were included in a study of genetic diversity and structure in fragmented and less fragmented landscapes, and differentiation at intercontinental and three regional levels. Isozyme electrophoresis of eight enzyme systems revealed 12 variable loci, which could be used for haplotype identification. A hierachical analysis of variance (AMOVA) revealed no significant intercontinental differentiation, and very limited differentiation among European regions. A trend of decreasing diversity with increasing latitude was apparent. Gametic phase disequilibria was high, suggesting nonrandom mating and regionally high incidences of inbreeding. The partitioning of genetic variation within and among populations in each region varied among regions, the northernmost populations having 86% of the total variation among populations, the southernmost in Scandinavia having 25% of the variation among populations, whereas the American populations displayed 89% of the variation within populations. Fifteen alleles at eight loci occurred in the U.S.A. which were not encountered in Europe, whereas only three European alleles at one locus in three populations were not encountered in U.S.A. The differences in diversity between North America and Europe may result from loss of genetic diversity caused by founder effects during postglacial recolonization of northern Europe. In Europe, the main mountain ranges extend E-W, posing severe barriers to northwards migration of lowland species, compared to the N-S trend of mountain ranges in North America. The decline in genetic diversity and increase in population differentiation and gametic phase disequilibria towards the north in Scandinavia may be caused by a series of founder effects during postglacial migration. These may have corresponded to minor climatic oscillations that influenced the migration front/leading edge in the suboceanic lowlands of Norway. According to this model random genetic drift will be an

Protective Effect of HLA-DQB1 Alleles Against Alloimmunization in Patients with Sickle Cell Disease

PubMed Central

Tatari-Calderone, Zohreh; Gordish-Dressman, Heather; Fasano, Ross; Riggs, Michael; Fortier, Catherine; Andrew; Campbell, D.; Charron, Dominique; Gordeuk, Victor R.; Luban, Naomi L.C.; Vukmanovic, Stanislav; Tamouza, Ryad

2015-01-01

Background Alloimmunization or the development of alloantibodies to Red Blood Cell (RBC) antigens is considered one of the major complications after RBC transfusions in patients with sickle cell disease (SCD) and can lead to both acute and delayed hemolytic reactions. It has been suggested that polymorphisms in HLA genes, may play a role in alloimmunization. We conducted a retrospective study analyzing the influence of HLA-DRB1 and DQB1 genetic diversity on RBC-alloimmunization. Study design Two-hundred four multi-transfused SCD patients with and without RBC-alloimmunization were typed at low/medium resolution by PCR-SSO, using IMGT-HLA Database. HLA-DRB1 and DQB1 allele frequencies were analyzed using logistic regression models, and global p-value was calculated using multiple logistic regression. Results While only trends towards associations between HLA-DR diversity and alloimmunization were observed, analysis of HLA-DQ showed that HLA-DQ2 (p=0.02), -DQ3 (p=0.02) and -DQ5 (p=0.01) alleles were significantly higher in non-alloimmunized patients, likely behaving as protective alleles. In addition, multiple logistic regression analysis showed both HLA-DQ2/6 (p=0.01) and HLA-DQ5/5 (p=0.03) combinations constitute additional predictor of protective status. Conclusion Our data suggest that particular HLA-DQ alleles influence the clinical course of RBC transfusion in patients with SCD, which could pave the way towards predictive strategies. PMID:26476208

Analysis of genetic diversity in Bolivian llama populations using microsatellites.

PubMed

Barreta, J; Gutiérrez-Gil, B; Iñiguez, V; Romero, F; Saavedra, V; Chiri, R; Rodríguez, T; Arranz, J J

2013-08-01

South American camelids (SACs) have a major role in the maintenance and potential future of rural Andean human populations. More than 60% of the 3.7 million llamas living worldwide are found in Bolivia. Due to the lack of studies focusing on genetic diversity in Bolivian llamas, this analysis investigates both the genetic diversity and structure of 12 regional groups of llamas that span the greater part of the range of distribution for this species in Bolivia. The analysis of 42 microsatellite markers in the considered regional groups showed that, in general, there were high levels of polymorphism (a total of 506 detected alleles; average PIC across per marker: 0.66), which are comparable with those reported for other populations of domestic SACs. The estimated diversity parameters indicated that there was high intrapopulational genetic variation (average number of alleles and average expected heterozygosity per marker: 12.04 and 0.68, respectively) and weak genetic differentiation among populations (FST range: 0.003-0.052). In agreement with these estimates, Bolivian llamas showed a weak genetic structure and an intense gene flow between all the studied regional groups, which is due to the exchange of reproductive males between the different flocks. Interestingly, the groups for which the largest pairwise FST estimates were observed, Sud Lípez and Nor Lípez, showed a certain level of genetic differentiation that is probably due to the pattern of geographic isolation and limited communication infrastructures of these southern localities. Overall, the population parameters reported here may serve as a reference when establishing conservation policies that address Bolivian llama populations. © 2012 Blackwell Verlag GmbH.

Genotype distribution and allele frequencies of the genes associated with body composition and locomotion traits in Myanmar native horses.

PubMed

Okuda, Yu; Moe, Hla Hla; Moe, Kyaw Kyaw; Shimizu, Yuki; Nishioka, Kenji; Shimogiri, Takeshi; Mannen, Hideyuki; Kanemaki, Misao; Kunieda, Tetsuo

2017-08-01

Myanmar native horses are small horses used mainly for drafting carts or carriages in rural areas and packing loads in mountainy areas. In the present study, we investigated genotype distributions and allele frequencies of the LCORL/NCAPG, MSTN and DMRT3 genes, which are associated with body composition and locomotion traits of horses, in seven local populations of Myanmar native horses. The genotyping result of LCORL/NCAPG showed that allele frequencies of C allele associated with higher withers height ranged from 0.08 to 0.27, and 0.13 in average. For MSTN, allele frequencies of C allele associated with higher proportion of Type 2B muscular fiber ranged from 0.05 to 0.23, and 0.09 in average. For DMRT3, allele frequencies of A allele associated with ambling gait ranged from 0 to 0.04, and 0.01 in average. The presences of the minor alleles of these genes at low frequencies suggest a possibility that these horse populations have not been under strong selection pressure for particular locomotion traits and body composition. Our findings of the presence of these minor alleles in Southeast Asian native horses are also informative for considering the origins of these minor alleles associated with body composition and locomotion traits in horse populations. © 2016 Japanese Society of Animal Science.

Mutant power: using mutant allele collections for yeast functional genomics.

PubMed

Norman, Kaitlyn L; Kumar, Anuj

2016-03-01

The budding yeast has long served as a model eukaryote for the functional genomic analysis of highly conserved signaling pathways, cellular processes and mechanisms underlying human disease. The collection of reagents available for genomics in yeast is extensive, encompassing a growing diversity of mutant collections beyond gene deletion sets in the standard wild-type S288C genetic background. We review here three main types of mutant allele collections: transposon mutagen collections, essential gene collections and overexpression libraries. Each collection provides unique and identifiable alleles that can be utilized in genome-wide, high-throughput studies. These genomic reagents are particularly informative in identifying synthetic phenotypes and functions associated with essential genes, including those modeled most effectively in complex genetic backgrounds. Several examples of genomic studies in filamentous/pseudohyphal backgrounds are provided here to illustrate this point. Additionally, the limitations of each approach are examined. Collectively, these mutant allele collections in Saccharomyces cerevisiae and the related pathogenic yeast Candida albicans promise insights toward an advanced understanding of eukaryotic molecular and cellular biology. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Molecular and morphological diversity in locally grown non-commercial (heirloom) mango varieties of North India.

PubMed

Bajpai, Anju; Muthukumar, M; Ahmad, Israr; Ravishankar, K V; Parthasarthy, V A; Sthapit, Bhuwon; Rao, Ramanatha; Verma, J P; Rajan, S

2016-03-01

Mango (Mangifera indica L.) has been cultivated and conserved in different agro-ecologies including Malihabad region in northern part of India, that is well known for housing diverse types (heirloom and commercial varieties). In the present study, 37 mango types comprising of 27 heirloom varieties from Malihabad region and 10 commercial varieties grown in North and Eastern India were assessed for morphological attributes and molecular diversity. The employed SSR markers amplified 2-13 alleles individually, cumulatively amplifying 124 alleles. These were studied for allelic diversity and genetic dissimilarity ranged from 0.035 to 0.892 arranging the varieties in three major clusters. The results revealed that majority of unique heirloom mangoes from Malihabad were different from the eastern part of the country. It is interesting to note Dashehari, a commercial variety from Malihabad was not aligned with heirloom varieties. Commercial varieties like Gulabkhas and Langra were placed in a separate group including Bombay Green, Himsagar, Dashehari, etc., indicating their dissimilarity with heirloom varieties at molecular level and thus, indicating importance for later from conservation point of view. Furthermore, the hierarchical clustering of varieties based on fruit morphology, assembled these into four groups largely influenced by fruit size. The maximum agreement subtree indicated seemingly good fit as thirteen varieties were arrayed in common grouping pattern. Appreciable dissimilarity among the heirloom varieties demonstrated by molecular analysis, underlines the importance for their on-farm conservation.

Development of Microsatellite Markers and Analysis of Genetic Diversity and Population Structure of Colletotrichum gloeosporioides from Ethiopia

PubMed Central

Moges, Asmare D.; Admassu, Belayneh; Belew, Derbew; Yesuf, Mohammed; Njuguna, Joyce; Kyalo, Martina; Ghimire, Sita R.

2016-01-01

Twenty three polymorphic microsatellite markers were developed for citrus plant pathogenic fungus, Colletotrichum gloeosporioides, and were used to analyze genetic diversity and population structure of 163 isolates from four different geographical regions of Ethiopia. These loci produced a total of 118 alleles with an average of 5.13 alleles per microsatellite marker. The polymorphic information content values ranged from 0.104 to 0.597 with an average of 0.371. The average observed heterozygosity across all loci varied from 0.046 to 0.058. The gene diversity among the loci ranged from 0.106 to 0.664. Unweighted Neighbor-joining and population structure analysis grouped these 163 isolates into three major groups. The clusters were not according to the geographic origin of the isolates. Analysis of molecular variance showed 85% of the total variation within populations and only 5% among populations. There was low genetic differentiation in the total populations (FST = 0.049) as evidenced by high level of gene flow estimate (Nm = 4.8 per generation) among populations. The results show that Ethiopian C. gloeosporioides populations are generally characterized by a low level of genetic diversity. The newly developed microsatellite markers were useful in analyzing the genetic diversity and population structure of the C. gloeosporioides populations. Information obtained from this study could be useful as a base to design strategies for better management of leaf and fruit spot disease of citrus in Ethiopia. PMID:26978654

Plasmodium relictum infection and MHC diversity in the house sparrow (Passer domesticus)

PubMed Central

Loiseau, Claire; Zoorob, Rima; Robert, Alexandre; Chastel, Olivier; Julliard, Romain; Sorci, Gabriele

2011-01-01

Antagonistic coevolution between hosts and parasites has been proposed as a mechanism maintaining genetic diversity in both host and parasite populations. In particular, the high level of genetic diversity usually observed at the major histocompatibility complex (MHC) is generally thought to be maintained by parasite-driven selection. Among the possible ways through which parasites can maintain MHC diversity, diversifying selection has received relatively less attention. This hypothesis is based on the idea that parasites exert spatially variable selection pressures because of heterogeneity in parasite genetic structure, abundance or virulence. Variable selection pressures should select for different host allelic lineages resulting in population-specific associations between MHC alleles and risk of infection. In this study, we took advantage of a large survey of avian malaria in 13 populations of the house sparrow (Passer domesticus) to test this hypothesis. We found that (i) several MHC alleles were either associated with increased or decreased risk to be infected with Plasmodium relictum, (ii) the effects were population specific, and (iii) some alleles had antagonistic effects across populations. Overall, these results support the hypothesis that diversifying selection in space can maintain MHC variation and suggest a pattern of local adaptation where MHC alleles are selected at the local host population level. PMID:20943698

Evaluation of Genetic Diversity and Development of a Core Collection of Wild Rice (Oryza rufipogon Griff.) Populations in China

PubMed Central

Bai, Lin; Lu, Zhenzhen; Chen, Yuhong; Jiang, Lan; Diao, Mengyang; Liu, Xiangdong; Lu, Yonggen

2015-01-01

Common wild rice (Oryza rufipogon Griff.), the progenitor of Asian cultivated rice (O. sativa L.), is endangered due to habitat loss. The objectives of this research were to evaluate the genetic diversity of wild rice species in isolated populations and to develop a core collection of representative genotypes for ex situ conservation. We collected 885 wild rice accessions from eight geographically distinct regions and transplanted these accessions in a protected conservation garden over a period of almost two decades. We evaluated these accessions for 13 morphological or phenological traits and genotyped them for 36 DNA markers evenly distributed on the 12 chromosomes. The coefficient of variation of quantitative traits was 0.56 and ranged from 0.37 to 1.06. SSR markers detected 206 different alleles with an average of 6 alleles per locus. The mean polymorphism information content (PIC) was 0.64 in all populations, indicating that the marker loci have a high level of polymorphism and genetic diversity in all populations. Phylogenetic analyses based on morphological and molecular data revealed remarkable differences in the genetic diversity of common wild rice populations. The results showed that the Zengcheng, Gaozhou, and Suixi populations possess higher levels of genetic diversity, whereas the Huilai and Boluo populations have lower levels of genetic diversity than do the other populations. Based on their genetic distance, 130 accessions were selected as a core collection that retained over 90% of the alleles at the 36 marker loci. This genetically diverse core collection will be a useful resource for genomic studies of rice and for initiatives aimed at developing rice with improved agronomic traits. PMID:26720755

Evaluation of Genetic Diversity and Development of a Core Collection of Wild Rice (Oryza rufipogon Griff.) Populations in China.

PubMed

Liu, Wen; Shahid, Muhammad Qasim; Bai, Lin; Lu, Zhenzhen; Chen, Yuhong; Jiang, Lan; Diao, Mengyang; Liu, Xiangdong; Lu, Yonggen

2015-01-01

Common wild rice (Oryza rufipogon Griff.), the progenitor of Asian cultivated rice (O. sativa L.), is endangered due to habitat loss. The objectives of this research were to evaluate the genetic diversity of wild rice species in isolated populations and to develop a core collection of representative genotypes for ex situ conservation. We collected 885 wild rice accessions from eight geographically distinct regions and transplanted these accessions in a protected conservation garden over a period of almost two decades. We evaluated these accessions for 13 morphological or phenological traits and genotyped them for 36 DNA markers evenly distributed on the 12 chromosomes. The coefficient of variation of quantitative traits was 0.56 and ranged from 0.37 to 1.06. SSR markers detected 206 different alleles with an average of 6 alleles per locus. The mean polymorphism information content (PIC) was 0.64 in all populations, indicating that the marker loci have a high level of polymorphism and genetic diversity in all populations. Phylogenetic analyses based on morphological and molecular data revealed remarkable differences in the genetic diversity of common wild rice populations. The results showed that the Zengcheng, Gaozhou, and Suixi populations possess higher levels of genetic diversity, whereas the Huilai and Boluo populations have lower levels of genetic diversity than do the other populations. Based on their genetic distance, 130 accessions were selected as a core collection that retained over 90% of the alleles at the 36 marker loci. This genetically diverse core collection will be a useful resource for genomic studies of rice and for initiatives aimed at developing rice with improved agronomic traits.

Genetic diversity and population structure analysis between Indian red jungle fowl and domestic chicken using microsatellite markers.

PubMed

Kumar, Vinay; Shukla, Sanjeev K; Mathew, Jose; Sharma, Deepak

2015-01-01

The present study was conducted to assess the genetic diversity, population structure, and relatedness in Indian red jungle fowl (RJF, Gallus gallus murgi) from northern India and three domestic chicken populations (gallus gallus domesticus), maintained at the institute farms, namely White Leghorn (WL), Aseel (AS) and Red Cornish (RC) using 25 microsatellite markers. All the markers were polymorphic, the number of alleles at each locus ranged from five (MCW0111) to forty-three (LEI0212) with an average number of 19 alleles per locus. Across all loci, the mean expected heterozygosity and polymorphic information content were 0.883 and 0.872, respectively. Population-specific alleles were found in each population. A UPGMA dendrogram based on shared allele distances clearly revealed two major clusters among the four populations; cluster I had genotypes from RJF and WL whereas cluster II had AS and RC genotypes. Furthermore, the estimation of population structure was performed to understand how genetic variation is partitioned within and among populations. The maximum ▵K value was observed for K = 4 with four identified clusters. Furthermore, factorial analysis clearly showed four clustering; each cluster represented the four types of population used in the study. These results clearly, demonstrate the potential of microsatellite markers in elucidating the genetic diversity, relationships, and population structure analysis in RJF and domestic chicken populations.

Evaluation of Allele-Specific Somatic Changes of Genome-Wide Association Study Susceptibility Alleles in Human Colorectal Cancers

PubMed Central

Gerber, Madelyn M.; Hampel, Heather; Schulz, Nathan P.; Fernandez, Soledad; Wei, Lai; Zhou, Xiao-Ping; de la Chapelle, Albert; Toland, Amanda Ewart

2012-01-01

Background Tumors frequently exhibit loss of tumor suppressor genes or allelic gains of activated oncogenes. A significant proportion of cancer susceptibility loci in the mouse show somatic losses or gains consistent with the presence of a tumor susceptibility or resistance allele. Thus, allele-specific somatic gains or losses at loci may demarcate the presence of resistance or susceptibility alleles. The goal of this study was to determine if previously mapped susceptibility loci for colorectal cancer show evidence of allele-specific somatic events in colon tumors. Methods We performed quantitative genotyping of 16 single nucleotide polymorphisms (SNPs) showing statistically significant association with colorectal cancer in published genome-wide association studies (GWAS). We genotyped 194 paired normal and colorectal tumor DNA samples and 296 paired validation samples to investigate these SNPs for allele-specific somatic gains and losses. We combined analysis of our data with published data for seven of these SNPs. Results No statistically significant evidence for allele-specific somatic selection was observed for the tested polymorphisms in the discovery set. The rs6983267 variant, which has shown preferential loss of the non-risk T allele and relative gain of the risk G allele in previous studies, favored relative gain of the G allele in the combined discovery and validation samples (corrected p-value = 0.03). When we combined our data with published allele-specific imbalance data for this SNP, the G allele of rs6983267 showed statistically significant evidence of relative retention (p-value = 2.06×10−4). Conclusions Our results suggest that the majority of variants identified as colon cancer susceptibility alleles through GWAS do not exhibit somatic allele-specific imbalance in colon tumors. Our data confirm previously published results showing allele-specific imbalance for rs6983267. These results indicate that allele-specific imbalance of cancer

Genetic diversity among silkworm (Bombyx mori L., Lep., Bombycidae) germplasms revealed by microsatellites.

PubMed

Li, Muwang; Shen, Li; Xu, Anying; Miao, Xuexia; Hou, Chengxiang; Sun, Pingjiang; Zhang, Yuehua; Huang, Yongping

2005-10-01

To determine genetic relationships among strains of silkworm, Bombyx mori L., 31 strains with different origins, number of generations per year, number of molts per generation, and morphological characters were studied using simple sequence repeat (SSR) markers. Twenty-six primer pairs flanking microsatellite sequences in the silkworm genome were assayed. All were polymorphic and unambiguously separated silkworm strains from each other. A total of 188 alleles were detected with a mean value of 7.2 alleles/locus (range 2-17). The average heterozygosity value for each SSR locus ranged from 0 to 0.60, and the highest one was 0.96 (Fl0516 in 4013). The mean polymorphism index content (PIC) was 0.66 (range 0.12-0.89). Unweighted pair group method with arithmetic means (UPGMA) cluster analysis of Nei's genetic distance grouped silkworm strains based on their origin. Seven major ecotypic silkworm groups were analyzed. Principal components analysis (PCA) for SSR data support their UPGMA clustering. The results indicated that SSR markers are an efficient tool for fingerprinting cultivars and conducting genetic-diversity studies in the silkworm.

The grain Hardness locus characterized in a diverse wheat panel (Triticum aestivum L.) adapted to the central part of the Fertile Crescent: genetic diversity, haplotype structure, and phylogeny.

PubMed

Shaaf, Salar; Sharma, Rajiv; Baloch, Faheem Shehzad; Badaeva, Ekaterina D; Knüpffer, Helmut; Kilian, Benjamin; Özkan, Hakan

2016-06-01

Wheat belongs to the most important crops domesticated in the Fertile Crescent. In this region, fortunately, locally adapted wheat landraces are still present in farmers' fields. This material might be of immense value for future breeding programs. However, especially wheat germplasm adapted to the central part of the Fertile Crescent has been poorly characterized for allelic variation at key loci of agricultural importance. Grain hardness is an important trait influencing milling and baking quality of wheat. This trait is mainly determined by three tightly linked genes, namely, Puroindoline a (Pina), Puroindoline b (Pinb), and Grain softness protein-1 (Gsp-1), at the Hardness (Ha-D) locus on chromosome 5DS. To investigate genetic diversity and haplotype structure, we resequenced 96 diverse wheat lines at Pina-D1, Pinb-D1, Gsp-A1, Gsp-B1, and Gsp-D1. Three types of null alleles were identified using diagnostic primers: the first type was a multiple deletion of Pina-D1, Pinb-D1, and Gsp-D1 (Pina-D1k), the second was a Pina-D1 deletion (Pina-D1b); and the third type was a deletion of Gsp-D1, representing a novel null allele designated here as Gsp-D1k. Sequence analysis resulted in four allelic variants at Pinb-D1 and five at Gsp-A1, among them Gsp-A1-V was novel. Pina-D1, Gsp-B1 and Gsp-D1 sequences were monomorphic. Haplotype and phylogenetic analysis suggested that (1) bread wheat inherited its 5DS telomeric region probably from wild diploid Ae. tauschii subsp. tauschii found within an area from Transcaucasia to Caspian Iran; and that (2) the Ha-A and Ha-B homoeoloci were most closely related to sequences of wild tetraploid T. dicocco ides. This study provides a good overview of available genetic diversity at Pina-D1, Pinb-D1, and Gsp-1, which can be exploited to extend the range of grain texture traits in wheat.

Influence of northern limit range on genetic diversity and structure in a widespread North American tree, sugar maple (Acer saccharum Marshall).

PubMed

Graignic, Noémie; Tremblay, Francine; Bergeron, Yves

2018-03-01

Due to climate change, the ranges of many North American tree species are expected to shift northward. Sugar maple ( Acer saccharum Marshall) reaches its northern continuous distributional limit in northeastern North America at the transition between boreal mixed-wood and temperate deciduous forests. We hypothesized that marginal fragmented northern populations from the boreal mixed wood would have a distinct pattern of genetic structure and diversity. We analyzed variation at 18 microsatellite loci from 23 populations distributed along three latitudinal transects (west, central, and east) that encompass the continuous-discontinuous species range. Each transect was divided into two zones, continuous (temperate deciduous) and discontinuous (boreal mixed wood), based on sugar maple stand abundance. Respective positive and negative relationships were found between the distance of each population to the northern limit (D_north), and allelic richness ( A R ) and population differentiation ( F ST ). These relations were tested for each transect separately; the pattern (discontinuous-continuous) remained significant only for the western transect. structure analysis revealed the presence of four clusters. The most northern populations of each transect were assigned to a distinct group. Asymmetrical gene flow occurred from the southern into the four northernmost populations. Southern populations in Québec may have originated from two different postglacial migration routes. No evidence was found to validate the hypothesis that northern populations were remnants of a larger population that had migrated further north of the species range after the retreat of the ice sheet. The northernmost sugar maple populations possibly originated from long-distance dispersal.

Forensic Loci Allele Database (FLAD): Automatically generated, permanent identifiers for sequenced forensic alleles.

PubMed

Van Neste, Christophe; Van Criekinge, Wim; Deforce, Dieter; Van Nieuwerburgh, Filip

2016-01-01

It is difficult to predict if and when massively parallel sequencing of forensic STR loci will replace capillary electrophoresis as the new standard technology in forensic genetics. The main benefits of sequencing are increased multiplexing scales and SNP detection. There is not yet a consensus on how sequenced profiles should be reported. We present the Forensic Loci Allele Database (FLAD) service, made freely available on http://forensic.ugent.be/FLAD/. It offers permanent identifiers for sequenced forensic alleles (STR or SNP) and their microvariants for use in forensic allele nomenclature. Analogous to Genbank, its aim is to provide permanent identifiers for forensically relevant allele sequences. Researchers that are developing forensic sequencing kits or are performing population studies, can register on http://forensic.ugent.be/FLAD/ and add loci and allele sequences with a short and simple application interface (API). Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Diversity of potato genetic resources

PubMed Central

Machida-Hirano, Ryoko

2015-01-01

A considerable number of highly diverse species exist in genus Solanum. Because they can adapt to a broad range of habitats, potato wild relatives are promising sources of desirable agricultural traits. Potato taxonomy is quite complex because of introgression, interspecific hybridization, auto- and allopolyploidy, sexual compatibility among many species, a mixture of sexual and asexual reproduction, possible recent species divergence, phenotypic plasticity, and the consequent high morphological similarity among species. Recent researchers using molecular tools have contributed to the identification of genes controlling several types of resistance as well as to the revision of taxonomical relationships among potato species. Historically, primitive forms of cultivated potato and its wild relatives have been used in breeding programs and there is still an enormous and unimaginable potential for discovering desirable characteristics, particularly in wild species Different methods have been developed to incorporate useful alleles from these wild species into the improved cultivars. Potato germplasm comprising of useful alleles for different breeding objectives is preserved in various gene banks worldwide. These materials, with their invaluable information, are accessible for research and breeding purposes. Precise identification of species base on the new taxonomy is essential for effective use of the germplasm collection. PMID:25931978

Evidence of low genetic variation and rare alleles in a bottlenecked endangered island endemic, the Lasan Teal (Anas laysanensis)

USGS Publications Warehouse

Reynolds, Michelle H.; Pearce, John M.; Lavretsky, Philip; Peters Jeffrey L,; Courtot, Karen; Seixas, Pedro P.

2015-01-01

Genetic diversity is assumed to reflect the evolutionary potential and adaptability of populations, and thus quantifying the genetic diversity of endangered species is useful for recovery programs. In particular, if conservation strategies include reintroductions, periodic genetic assessments are useful to evaluate whether management efforts have resulted in the maximization or loss of genetic variation within populations over generations. In this study, we collected blood, feather, and tissue samples during 1999–2009 and quantified genetic diversity for a critically endangered waterfowl species endemic to the Hawaiian archipelago, the Laysan teal or duck (Anas laysanensis; n = 239 individual birds sampled). The last extant population of this species at Laysan Island was sourced in 2004–2005 for a ‘wild to wild’ translocation of 42 individuals for an experimental reintroduction to Midway Atoll. To inform future management strategies, we compared genetic diversity sampled from the source population (n = 133 Laysan birds) including 23 of Midway’s founders and offspring of the translocated population 2–5 years post release (n = 96 Midway birds). We attempted to identify polymorphic markers by screening nuclear microsatellite (N = 83) and intronic loci (N = 19), as well as the mitochondrial control region (mtDNA) for a subset of samples. Among 83 microsatellite loci screened, six were variable. We found low nuclear variation consistent with the species’ historical population bottlenecks and sequence variation was observed at a single intron locus. We detected no variation within the mtDNA. We found limited but similar estimates of allelic richness (2.58 alleles per locus) and heterozygosity within islands. Two rare alleles found in the Laysan Island source population were not present in the Midway translocated group, and a rare allele was discovered in an individual on Midway in 2008. We found similar genetic diversity and low, but statistically

Mechanisms for dominance: Adh heterodimer formation in heterozygotes between ENU or x-ray induced null alleles and normal alleles in drosophila melanogaster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, J.C.; Lee, W.R.; Chang, S.H.

1992-01-01

To study mechanisms for dominance of phenotype, eight ENU- and four x-ray-induced mutations at the alcohol dehydrogenase (Adh) locus were analyzed for partial dominance in their interaction with normal alleles. All ENU and one of the x-ray mutations were single base substitutions; the other three x-ray mutations were 9-21 base deletions. All but one of the 12 mutant alleles were selected for this study because they produced detectable mutant polypeptides, but seven of the 11 producing a peptide could not form dimers with the normal peptide and the enzyme activity of heterozygotes was about half that of normal homozygotes. Fourmore » mutations formed dimers with a decreased catalytic efficiency and two of these were near the limit of detectability; these two also inhibited the formation of normal homodimers. The mutant alleles therefore show multiple mechanisms leading to partial enzyme expression in heterozygotes and a wide range of dominance ranging from almost complete recessive to nearly dominant. All amino acid changes in mutant peptides that form dimers are located between amino acids 182 and 194, so this region is not critical for dimerization. It may, however, be an important surface domain for catalyzation. 34 refs., 8 figs., 2 tabs.« less

Whole genome SNP discovery and analysis of genetic diversity in Turkey (Meleagris gallopavo)

PubMed Central

2012-01-01

Background The turkey (Meleagris gallopavo) is an important agricultural species and the second largest contributor to the world’s poultry meat production. Genetic improvement is attributed largely to selective breeding programs that rely on highly heritable phenotypic traits, such as body size and breast muscle development. Commercial breeding with small effective population sizes and epistasis can result in loss of genetic diversity, which in turn can lead to reduced individual fitness and reduced response to selection. The presence of genomic diversity in domestic livestock species therefore, is of great importance and a prerequisite for rapid and accurate genetic improvement of selected breeds in various environments, as well as to facilitate rapid adaptation to potential changes in breeding goals. Genomic selection requires a large number of genetic markers such as e.g. single nucleotide polymorphisms (SNPs) the most abundant source of genetic variation within the genome. Results Alignment of next generation sequencing data of 32 individual turkeys from different populations was used for the discovery of 5.49 million SNPs, which subsequently were used for the analysis of genetic diversity among the different populations. All of the commercial lines branched from a single node relative to the heritage varieties and the South Mexican turkey population. Heterozygosity of all individuals from the different turkey populations ranged from 0.17-2.73 SNPs/Kb, while heterozygosity of populations ranged from 0.73-1.64 SNPs/Kb. The average frequency of heterozygous SNPs in individual turkeys was 1.07 SNPs/Kb. Five genomic regions with very low nucleotide variation were identified in domestic turkeys that showed state of fixation towards alleles different than wild alleles. Conclusion The turkey genome is much less diverse with a relatively low frequency of heterozygous SNPs as compared to other livestock species like chicken and pig. The whole genome SNP discovery

Association of the HLA-B*52 allele with non-progression to AIDS in Brazilian HIV-1-infected individuals.

PubMed

Teixeira, S L M; de Sá, N B R; Campos, D P; Coelho, A B; Guimarães, M L; Leite, T C N F; Veloso, V G; Morgado, M G

2014-04-01

Several human leukocyte antigen (HLA) class I alleles are associated with the susceptibility to human immunodeficiency virus-1 (HIV-1) infection and/or AIDS progression. Of these, the HLA-B alleles are considered the strongest genetic determinant of disease outcome. We evaluated the influence of the HLA-B alleles on AIDS progression among HIV-1-positive individuals from Rio de Janeiro, Brazil, who were categorized as rapid progressors (RPs), typical progressors (TPs) or long-term non-progressors (LTNPs). In this study, significant differences in HLA-B allele frequencies were observed among the three progression groups for the B*48, B*49 and B*52 alleles. After controlling for other factors associated with AIDS progression, the presence of the B*52 allele was shown to be a significant protective factor (hazard ratio (HR) 0.49 (95% confidence interval (CI) 0.27-0.90) P<0.03). Although no direct association was observed between the presence of the B*27 or B*57 allele and the LTNP profile compared with the TP or RP groups, the adjusted model confirmed that these alleles are protective factors against AIDS progression (HR 0.62 (95% CI 0.38-0.99) P<0.05), as previously described. These data corroborate the existence of significant differences in HLA-B allele frequencies among the distinct AIDS progression profiles and further elucidate the role of HLA alleles in the outcome of HIV infections in diverse populations.

HLA-A, HLA-B and HLA-DRB1 allele and haplotype frequencies of 10 918 Koreans from bone marrow donor registry in Korea.

PubMed

Park, H; Lee, Y-J; Song, E Y; Park, M H

2016-10-01

The human leucocyte antigen (HLA) system is the most polymorphic genetic system in humans, and HLA matching is crucial in organ transplantation, especially in hematopoietic stem cell transplantation. We investigated HLA-A, HLA-B and HLA-DRB1 allele and haplotype frequencies at allelic level in 10 918 Koreans from bone marrow donor registry in Korea. Intermediate resolution HLA typing was performed using Luminex technology (Wakunaga, Japan), and additional allelic level typing was performed using PCR-single-strand conformation polymorphism method and/or sequence-based typing (Abbott Molecular, USA). Allele and haplotype frequencies were calculated by direct counting and maximum likelihood methods, respectively. A total of 39 HLA-A, 66 HLA-B and 47 HLA-DRB1 alleles were identified. High-frequency alleles found at a frequency of ≥5% were 6 HLA-A (A*02:01, *02:06, *11:01, *24:02, *31:01 and *33:03), 6 HLA-B (B*15:01, *35:01, *44:03, *51:01, 54:01 and *58:01) and 8 HLA-DRB1 (DRB1*01:01, *04:05, *04:06, *07:01, *08:03, *09:01, *13:02 and *15:01) alleles. At each locus, A*02, B*15 and DRB1*14 generic groups were most diverse at allelic level, consisting of 9, 12 and 11 different alleles, respectively. A total of 366, 197 and 21 different HLA-A-B-DRB1 haplotypes were estimated with frequencies of ≥0.05%, ≥0.1% and ≥0.5%, respectively. The five most common haplotypes with frequencies of ≥2.0% were A*33:03-B*44:03-DRB1*13:02 (4.97%), A*33:03-B*58:01-DRB1*13:02, A*33:03-B*44:03-DRB1*07:01, A*24:02-B*07:02-DRB1*01:01 and A*24:02-B*52:01-DRB1*15:02. Among 34 serologic HLA-A-B-DR haplotypes with frequencies of ≥0.5%, 17 haplotypes revealed allele-level diversity and majority of the allelic variation was arising from A2, A26, B61, B62, DR4 and DR14 specificities. Haplotype diversity obtained in this study is the most comprehensive data thus far reported in Koreans, and the information will be useful for unrelated stem cell transplantation as well as for disease

Diversity, distribution of Puroindoline genes and their effect on kernel hardness in a diverse panel of Chinese wheat germplasm.

PubMed

Ma, Xiaoling; Sajjad, Muhammad; Wang, Jing; Yang, Wenlong; Sun, Jiazhu; Li, Xin; Zhang, Aimin; Liu, Dongcheng

2017-09-20

Kernel hardness, which has great influence on the end-use properties of common wheat, is mainly controlled by Puroindoline genes, Pina and Pinb. Using EcoTILLING platform, we herein investigated the allelic variations of Pina and Pinb genes and their association with the Single Kernel Characterization System (SKCS) hardness index in a diverse panel of wheat germplasm. The kernel hardness varied from 1.4 to 102.7, displaying a wide range of hardness index. In total, six Pina and nine Pinb alleles resulting in 15 genotypes were detected in 1787 accessions. The most common alleles are the wild type Pina-D1a (90.4%) and Pina-D1b (7.4%) for Pina, and Pinb-D1b (43.6%), Pinb-D1a (41.1%) and Pinb-D1p (12.8%) for Pinb. All the genotypes have hard type kernel hardness of SKCS index (>60.0), except the wild types of Pina and Pinb combination (Pina-D1a/Pinb-D1a). The most frequent genotypes in Chinese and foreign cultivars was Pina-D1a/Pinb-D1b (46.3 and 39.0%, respectively) and in Chinese landraces was Pina-D1a/Pinb-D1a (54.2%). The frequencies of hard type accessions are increasing from 35.5% in the region IV, to 40.6 and 61.4% in the regions III and II, and then to 77.0% in the region I, while those of soft type are accordingly decreasing along with the increase of latitude. Varieties released after 2000 in Beijing, Hebei, Shandong and Henan have higher average kernel hardness index than that released before 2000. The kernel hardness in a diverse panel of Chinese wheat germplasm revealed an increasing of kernel hardness generally along with the latitude across China. The wild type Pina-D1a and Pinb-D1a, and one Pinb mutant (Pinb-D1b) are the most common alleles of six Pina and nine Pinb alleles, and a new double null genotype (Pina-D1x/Pinb-D1ah) possessed relatively high SKCS hardness index. More hard type varieties were released in recent years with different prevalence of Pin-D1 combinations in different regions. This work would benefit the understanding of the selection

High-resolution HLA allele and haplotype frequencies in majority and minority populations of Costa Rica and Nicaragua: Differential admixture proportions in neighboring countries.

PubMed

Arrieta-Bolaños, E; Madrigal-Sánchez, J J; Stein, J E; Órlich-Pérez, P; Moreira-Espinoza, M J; Paredes-Carias, E; Vanegas-Padilla, Y; Salazar-Sánchez, L; Madrigal, J A; Marsh, S G E; Shaw, B E

2018-06-01

The HLA system shows the most extensive polymorphism in the human genome. Allelic and haplotypic frequencies of HLA genes vary dramatically across human populations. Due to a complex history of migration, populations in Latin America show a broad variety of admixture proportions, usually varying not only between countries, but also within countries. Knowledge of HLA allele and haplotype frequencies is essential for medical fields such as transplantation, but also serves as a means to assess genetic diversity and ancestry in human populations. Here, we have determined high-resolution HLA-A, -B, -C, and -DRB1 allele and haplotype frequencies in a sample of 713 healthy subjects from three Mestizo populations, one population of African descent, and Amerindians of five different groups from Costa Rica and Nicaragua and compared their profiles to a large set of indigenous populations from Iberia, Sub-Saharan Africa, and the Americas. Our results show a great degree of allelic and haplotypic diversity within and across these populations, with most extended haplotypes being private. Mestizo populations show alleles and haplotypes of putative European, Amerindian, and Sub-Saharan African origin, albeit with differential proportions. Despite some degree of gene flow, Amerindians and Afro-descendants show great similarity to other Amerindian and West African populations, respectively. This is the first comprehensive study reporting high-resolution HLA diversity in Central America, and its results will shed light into the genetic history of this region while also supporting the development of medical programs for organ and stem cell transplantation. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Natural variation in non-coding regions underlying phenotypic diversity in budding yeast

PubMed Central

Salinas, Francisco; de Boer, Carl G.; Abarca, Valentina; García, Verónica; Cuevas, Mara; Araos, Sebastian; Larrondo, Luis F.; Martínez, Claudio; Cubillos, Francisco A.

2016-01-01

Linkage mapping studies in model organisms have typically focused their efforts in polymorphisms within coding regions, ignoring those within regulatory regions that may contribute to gene expression variation. In this context, differences in transcript abundance are frequently proposed as a source of phenotypic diversity between individuals, however, until now, little molecular evidence has been provided. Here, we examined Allele Specific Expression (ASE) in six F1 hybrids from Saccharomyces cerevisiae derived from crosses between representative strains of the four main lineages described in yeast. ASE varied between crosses with levels ranging between 28% and 60%. Part of the variation in expression levels could be explained by differences in transcription factors binding to polymorphic cis-regulations and to differences in trans-activation depending on the allelic form of the TF. Analysis on highly expressed alleles on each background suggested ASN1 as a candidate transcript underlying nitrogen consumption differences between two strains. Further promoter allele swap analysis under fermentation conditions confirmed that coding and non-coding regions explained aspartic and glutamic acid consumption differences, likely due to a polymorphism affecting Uga3 binding. Together, we provide a new catalogue of variants to bridge the gap between genotype and phenotype. PMID:26898953

Assessment of genetic diversity in Vigna unguiculata L. (Walp) accessions using inter-simple sequence repeat (ISSR) and start codon targeted (SCoT) polymorphic markers.

PubMed

Igwe, David Okeh; Afiukwa, Celestine Azubike; Ubi, Benjamin Ewa; Ogbu, Kenneth Idika; Ojuederie, Omena Bernard; Ude, George Nkem

2017-11-17

Assessment of genetic diversity of Vigna unguiculata (L.) Walp (cowpea) accessions using informative molecular markers is imperative for their genetic improvement and conservation. Use of efficacious molecular markers to obtain the required knowledge of the genetic diversity within the local and regional germplasm collections can enhance the overall effectiveness of cowpea improvement programs, hence, the comparative assessment of Inter-simple sequence repeat (ISSR) and Start codon targeted (SCoT) markers in genetic diversity of V. unguiculata accessions from different regions in Nigeria. Comparative analysis of the genetic diversity of eighteen accessions from different locations in Nigeria was investigated using ISSR and SCoT markers. DNA extraction was done using Zymogen Kit according to its manufacturer's instructions followed by amplifications with ISSR and SCoT and agarose gel electrophoresis. The reproducible bands were scored for analyses of dendrograms, principal component analysis, genetic diversity, allele frequency, polymorphic information content, and population structure. Both ISSR and SCoT markers resolved the accessions into five major clusters based on dendrogram and principal component analyses. Alleles of 32 and 52 were obtained with ISSR and SCoT, respectively. Numbers of alleles, gene diversity and polymorphic information content detected with ISSR were 9.4000, 0.7358 and 0.7192, while SCoT yielded 11.1667, 0.8158 and 0.8009, respectively. Polymorphic loci were 70 and 80 in ISSR and SCoT, respectively. Both markers produced high polymorphism (94.44-100%). The ranges of effective number of alleles (Ne) were 1.2887 ± 0.1797-1.7831 ± 0.2944 and 1.7416 ± 0.0776-1.9181 ± 0.2426 in ISSR and SCoT, respectively. The Nei's genetic diversity (H) ranged from 0.2112 ± 0.0600-0.4335 ± 0.1371 and 0.4111 ± 0.0226-0.4778 ± 0.1168 in ISSR and SCoT, respectively. Shannon's information index (I) from ISSR and SCoT were 0

Genetic diversity of functional food species Spinacia oleracea L. by protein markers.

PubMed

Rashid, M; Yousaf, Z; Haider, M S; Khalid, S; Rehman, H A; Younas, A; Arif, A

2014-01-01

Exploration of genetic diversity contributes primarily towards crop improvement. Spinaciaoleracea L. is a functional food species but unfortunately the genetic diversity of this vegetable is still unexplored. Therefore, this research was planned to explore the genetic diversity of S. oleracea by using morphological and protein markers. Protein profile of 25 accessions was generated on sodium dodecyl sulphate polyacrylamide gel. Total allelic variation of 27 bands was found. Out of these, 20 were polymorphic and the rest of the bands were monomorphic. Molecular weights of the bands ranged from 12.6 to 91.2 kDa. Major genetic differences were observed in accession 20541 (Peshawar) followed by 20180 (Lahore) and 19902 (AVRDC). Significant differences exist in the protein banding pattern. This variation can further be studied by advanced molecular techniques, including two-dimensional electrophoresis and DNA markers.

Genetic Diversity and Population Structure of Broomcorn Millet (Panicum miliaceum L.) Cultivars and Landraces in China Based on Microsatellite Markers

PubMed Central

Liu, Minxuan; Xu, Yue; He, Jihong; Zhang, Shuang; Wang, Yinyue; Lu, Ping

2016-01-01

Broomcorn millet (Panicum miliaceum L.), one of the first domesticated crops, has been grown in Northern China for at least 10,000 years. The species is presently a minor crop, and evaluation of its genetic diversity has been very limited. In this study, we analyzed the genetic diversity of 88 accessions of broomcorn millet collected from various provinces of China. Amplification with 67 simple sequence repeat (SSR) primers revealed moderate levels of diversity in the investigated accessions. A total of 179 alleles were detected, with an average of 2.7 alleles per locus. Polymorphism information content and expected heterozygosity ranged from 0.043 to 0.729 (mean = 0.376) and 0.045 to 0.771 (mean = 0.445), respectively. Cluster analysis based on the unweighted pair group method of mathematical averages separated the 88 accessions into four groups at a genetic similarity level of 0.633. A genetic structure assay indicated a close correlation between geographical regions and genetic diversity. The uncovered information will be valuable for defining gene pools and developing breeding programs for broomcorn millet. Furthermore, the millet-specific SSR markers developed in this study should serve as useful tools for assessment of genetic diversity and elucidation of population structure in broomcorn millet. PMID:26985894

Short mucin 6 alleles are associated with H pylori infection.

PubMed

Nguyen, Thai V; Janssen, Marcel; Gritters, Paulien; te Morsche, René H M; Drenth, Joost P H; van Asten, Henri; Laheij, Robert J F; Jansen, Jan B M J

2006-10-07

To investigate the relationship between mucin 6 (MUC6) VNTR length and H pylori infection. Blood samples were collected from patients visiting the Can Tho General Hospital for upper gastrointestinal endoscopy. DNA was isolated from whole blood, the repeated section was cut out using a restriction enzyme (Pvu II) and the length of the allele fragments was determined by Southern blotting. H pylori infection was diagnosed by (14)C urea breath test. For analysis, MUC6 allele fragment length was dichotomized as being either long (> 13.5 kbp) or short (< or = 13.5 kbp) and patients were classified according to genotype [long-long (LL), long-short (LS), short-short (SS)]. 160 patients were studied (mean age 43 years, 36% were males, 58% H pylori positive). MUC6 Pvu II-restricted allele fragment lengths ranged from 7 to 19 kbp. Of the patients with the LL, LS, SS MUC6 genotype, 43% (24/56), 57% (25/58) and 76% (11/46) were infected with H pylori, respectively (P = 0.003). Short MUC6 alleles are associated with H pylori infection.

Genetic diversity of dispersed seeds is highly variable among leks of the long-wattled umbrellabird

NASA Astrophysics Data System (ADS)

Ottewell, Kym; Browne, Luke; Cabrera, Domingo; Olivo, Jorge; Karubian, Jordan

2018-01-01

Frugivorous animals frequently generate clumped distributions of seeds away from source trees, but genetic consequences of this phenomenon remain poorly resolved. Seed dispersal of the palm Oenocarpus bataua by long-wattled umbrellabirds Cephalopterus penduliger generates high seed densities in leks (i.e., multi-male display sites), providing a suitable venue to investigate how dispersal by this frugivore may influence seed source diversity and genetic structure at local and landscape levels. We found moderate levels of maternal seed source diversity in primary seed rain across five leks in northwest Ecuador (unweighted mean alpha diversity α = 9.52, weighted mean αr = 3.52), with considerable variation among leks (αr range: 1.81-24.55). Qualitatively similar findings were obtained for allelic diversity and heterozygosity. Higher densities of O. bataua adults around leks were associated with higher values of αr and heterozygosity (non-significant trends) and allelic diversity (significant correlation). Seed source overlap between different leks was not common but did occur at low frequency, providing evidence for long-distance seed dispersal by umbrellabirds into leks. Our findings are consistent with the idea that seed pool diversity within leks may be shaped by the interaction between density of local trees, which can vary considerably between leks, and umbrellabird foraging ecology, particularly a lack of territorial defense of fruiting trees. Taken as a whole, this work adds to our growing appreciation of the ways resource distribution and associated frugivore foraging behaviors mechanistically shape seed dispersal outcomes and the distribution of plant genotypes across the landscape.

Assessment of genetic diversity, population structure and relationships in Indian and non-Indian genotypes of finger millet (Eleusine coracana (L.) Gaertn) using genomic SSR markers.

PubMed

Ramakrishnan, M; Antony Ceasar, S; Duraipandiyan, V; Al-Dhabi, N A; Ignacimuthu, S

2016-01-01

We evaluated the genetic variation and population structure in Indian and non-Indian genotypes of finger millet using 87 genomic SSR primers. The 128 finger millet genotypes were collected and genomic DNA was isolated. Eighty-seven genomic SSR primers with 60-70 % GC contents were used for PCR analysis of 128 finger millet genotypes. The PCR products were separated and visualized on a 6 % polyacrylamide gel followed by silver staining. The data were used to estimate major allele frequency using Power Marker v3.0. Dendrograms were constructed based on the Jaccard's similarity coefficient. Statistical fitness and population structure analyses were performed to find the genetic diversity. The mean major allele frequency was 0.92; the means of polymorphic alleles were 2.13 per primer and 1.45 per genotype; the average polymorphism was 59.94 % per primer and average PIC value was 0.44 per primer. Indian genotypes produced an additional 0.21 allele than non-Indian genotypes. Gene diversity was in the range from 0.02 to 0.35. The average heterozygosity was 0.11, close to 100 % homozygosity. The highest inbreeding coefficient was observed with SSR marker UGEP67. The Jaccard's similarity coefficient value ranged from 0.011 to 0.836. The highest similarity value was 0.836 between genotypes DPI009-04 and GPU-45. Indian genotypes were placed in Eleusine coracana major cluster (EcMC) 1 along with 6 non-Indian genotypes. AMOVA showed that molecular variance in genotypes from various geographical regions was 4 %; among populations it was 3 % and within populations it was 93 %. PCA scatter plot analysis showed that GPU-28, GPU-45 and DPI009-04 were closely dispersed in first component axis. In structural analysis, the genotypes were divided into three subpopulations (SP1, SP2 and SP3). All the three subpopulations had an admixture of alleles and no pure line was observed. These analyses confirmed that all the genotypes were genetically diverse and had been grouped based on

Genetic diversity and phylogenetic relationships in local cattle breeds of Senegal based on autosomal microsatellite markers

PubMed Central

Ndiaye, Ndèye Penda; Sow, Adama; Dayo, Guiguigbaza-Kossigan; Ndiaye, Saliou; Sawadogo, Germain Jerôme; Sembène, Mbacké

2015-01-01

Aim: In Senegal, uncontrolled cross-breeding of cattle breeds and changes in production systems are assumed to lead to an increase of gene flow between populations. This might constitute a relevant threat to livestock improvement. Therewith, this study was carried out to assess the current genetic diversity and the phylogenetic relationships of the four native Senegalese cattle breeds (Gobra zebu, Maure zebu, Djakoré, and N’Dama). Methods: Genomic DNA was isolated from blood samples of 120 unrelated animals collected from three agro-ecological areas of Senegal according to their phenotypic traits. Genotyping was done using 11 specific highly polymorphic microsatellite makers recommended by Food and Agriculture Organization. The basic measures of genetic variation and phylogenetic trees were computed using bioinformatics’ software. Results: A total of 115 alleles were identified with a number of alleles (Na) at one locus ranging from 6 to 16. All loci were polymorphic with a mean polymorphic information content of 0.76. The mean allelic richness (Rs) lay within the narrow range of 5.14 in N’Dama taurine to 6.10 in Gobra zebu. While, the expected heterozygosity (HE) per breed was high in general with an overall mean of 0.76±0.04. Generally, the heterozygote deficiency (FIS) of 0.073±0.026 was relatively due to inbreeding among these cattle breeds or the occurrence of population substructure. The high values of allelic and gene diversity showed that Senegalese native cattle breeds represented an important reservoir of genetic variation. The genetic distances and clustering trees concluded that the N’Dama cattle were most distinct among the investigated cattle populations. So, the principal component analyses showed qualitatively that there was an intensive genetic admixture between the Gobra zebu and Maure zebu breeds. Conclusions: The broad genetic diversity in Senegalese cattle breeds will allow for greater opportunities for improvement of productivity

Comparison of SSR and SNP Markers in Estimation of Genetic Diversity and Population Structure of Indian Rice Varieties

PubMed Central

Singh, Amit Kumar; Kumar, Sundeep; Srinivasan, Kalyani; Tyagi, R. K.; Singh, N. K.; Singh, Rakesh

2013-01-01

Simple sequence repeat (SSR) and Single Nucleotide Polymorphic (SNP), the two most robust markers for identifying rice varieties were compared for assessment of genetic diversity and population structure. Total 375 varieties of rice from various regions of India archived at the Indian National GeneBank, NBPGR, New Delhi, were analyzed using thirty six genetic markers, each of hypervariable SSR (HvSSR) and SNP which were distributed across 12 rice chromosomes. A total of 80 alleles were amplified with the SSR markers with an average of 2.22 alleles per locus whereas, 72 alleles were amplified with SNP markers. Polymorphic information content (PIC) values for HvSSR ranged from 0.04 to 0.5 with an average of 0.25. In the case of SNP markers, PIC values ranged from 0.03 to 0.37 with an average of 0.23. Genetic relatedness among the varieties was studied; utilizing an unrooted tree all the genotypes were grouped into three major clusters with both SSR and SNP markers. Analysis of molecular variance (AMOVA) indicated that maximum diversity was partitioned between and within individual level but not between populations. Principal coordinate analysis (PCoA) with SSR markers showed that genotypes were uniformly distributed across the two axes with 13.33% of cumulative variation whereas, in case of SNP markers varieties were grouped into three broad groups across two axes with 45.20% of cumulative variation. Population structure were tested using K values from 1 to 20, but there was no clear population structure, therefore Ln(PD) derived Δk was plotted against the K to determine the number of populations. In case of SSR maximum Δk was at K=5 whereas, in case of SNP maximum Δk was found at K=15, suggesting that resolution of population was higher with SNP markers, but SSR were more efficient for diversity analysis. PMID:24367635

Genetic diversity of the msp-1, msp-2, and glurp genes of Plasmodium falciparum isolates along the Thai-Myanmar borders.

PubMed

Congpuong, Kanungnit; Sukaram, Rungniran; Prompan, Yuparat; Dornae, Aibteesam

2014-08-01

To study the genetic diversity at the msp-1, msp-2, and glurp genes of Plasmodium falciparum (P. falciparum) isolates from 3 endemic areas in Thailand: Tak, Kanchanaburi and Ranong provinces. A total of 144 P. falciparum isolates collected prior to treatment during January, 2012 to June, 2013 were genotyped. DNA was extracted; allele frequency and diversity of msp-1, msp-2, and glurp genes were investigated by nested polymerase chain reaction. P. falciparum isolates in this study had high rate of multiple genotypes infection (96.5%) with an overall mean multiplicity of infection of 3.21. The distribution of allelic families of msp-1 was significantly different among isolates from Tak, Kanchanaburi, and Ranong but not for the msp-2. K1 and MAD20 were the predominant allelic families at the msp-1 gene, whereas alleles belonging to 3D7 were more frequent at the msp-2 gene. The glurp gene had the least diverse alleles. Population structure of P. falciparum isolates from Tak and Ranong was quite similar as revealed by the presence of similar proportions of MAD20 and K1 alleles at msp-1 loci, 3D7 and FC27 alleles at msp-2 loci as well as comparable mean MOI. Isolates from Kanchanaburi had different structures; the most prevalent alleles were K1 and RO33. The present study shows that P. falciparum isolates from Tak and Ranong provinces had similar allelic pattern of msp-1 and msp-2 and diversity but different from Kanchanaburi isolates. These allelic variant profiles are valuable baseline data for future epidemiological study of malaria transmission and for continued monitoring of polymorphisms associated with antimalarial drug resistance in these areas.

The Plasmodium gaboni genome illuminates allelic dimorphism of immunologically important surface antigens in P. falciparum.

PubMed

Roy, Scott William

2015-12-01

In the deadly human malaria parasite Plasmodium falciparum, several major merozoite surface proteins (MSPs) show a striking pattern of allelic diversity called allelic dimorphism (AD). In AD, the vast majority of observed alleles fall into two highly divergent allelic classes, with recombinant alleles being rare or not observed, presumably due to repression by natural selection (recombination suppression, or RS). The three AD loci, merozoite surface proteins (MSPs) 1, 2, and 6, along with MSP3, which also exhibits RS among four allelic classes, can be collectively called AD/RS. The causes of AD/RS and the evolutionary history of allelic diversity at these loci remain mysterious. The few available sequences from a single closely related chimpanzee parasite, P. reichenowi, have suggested that for 3/4 loci, AD/RS is an ancient state that has been retained in P. falciparum since well before the P. falciparum-P. reichenowi ancestor. On the other hand, based on comparative sequence analysis, we recently suggested that (i) AD/RS P. falciparum loci have undergone interallelic recombination over longer evolutionary times (on the timescale of recent speciation events), and thus (ii) AD/RS may be a recent phenomenon. The recent publication of genomic sequencing efforts for P. gaboni, an outgroup to P. falciparum and P. reichenowi, allows for improved reconstruction of the evolutionary history of these loci. In this work, I report genic sequence for P. gaboni for all four AD/RS P. falciparum loci (MSP1, 2, 3, and 6). Comparison of these sequences with available P. falciparum and P. reichenowi data strengthens the evidence for interallelic recombination over the evolutionary history of these species and also strengthens the case that AD/RS at these loci is ancient. Combined with previous results, these data provide evidence that AD/RS at different loci has evolved at several different times in the evolutionary history of P. falciparum: (i) before the P. gaboni-P. falciparum

Diversity at the major histocompatibility complex Class II in the platypus, Ornithorhynchus anatinus.

PubMed

Lillie, Mette; Woodward, Rachael E; Sanderson, Claire E; Eldridge, Mark D B; Belov, Katherine

2012-07-01

The platypus (Ornithorhynchus anatinus) is the sole survivor of a previously widely distributed and diverse lineage of ornithorhynchid monotremes. Its dependence on healthy water systems imposes an inherent sensitivity to habitat degradation and climate change. Here, we compare genetic diversity at the major histocompatibility complex (MHC) Class II-DZB gene and 3 MHC-associated microsatellite markers with diversity at 6 neutral microsatellite markers in 70 platypuses from across their range, including the mainland of Australia and the isolated populations of Tasmania, King Island, and Kangaroo Island. Overall, high DZB diversity was observed in the platypus, with 57 DZB β1 alleles characterized. Significant positive selection was detected within the DZB peptide-binding region, promoting variation in this domain. Low levels of genetic diversity were detected at all markers in the 2 island populations, King Island (endemic) and Kangaroo Island (introduced), with the King Island platypuses monomorphic at the DZB locus. Loss of MHC diversity on King Island is of concern, as the population may have compromised immunological fitness and reduced ability to resist changing environmental conditions.

Dog leucocyte antigen class II diversity and relationships among indigenous dogs of the island nations of Indonesia (Bali), Australia and New Guinea.

PubMed

Runstadler, J A; Angles, J M; Pedersen, N C

2006-11-01

The genetic polymorphism at the dog leucocyte antigen (DLA) class II loci DQA1, DQB1 and DRB1 was studied in a large genetically diverse population of feral and wild-type dogs from the large island nations of Indonesia (Bali), Australia and New Guinea (Bali street dog, dingo and New Guinea singing dog, respectively). Sequence-based typing (SBT) of the hypervariable region of DLA-DRB1, -DQA1 and -DQB1 alleles was used to determine genetic diversity. No new DQA1 alleles were recognized among the three dog populations, but five novel DLA-DRB1 and 2 novel DLA-DQB1 allele sequences were detected. Additional unknown alleles were postulated to exist in Bali street dogs, as indicated by the large percentage of individuals (15%-33%) that had indeterminate DRB1, DQA1 and DQB1 alleles by SBT. All three groups of dogs possessed alleles that were relatively uncommon in conventional purebreds. The New Guinea singing dog and dingo shared alleles that were not present in the Bali street dogs. These findings suggested that the dingo was more closely related to indigenous dogs from New Guinea. Feral dog populations, in particular large ones such as that of Bali, show genetic diversity that existed prior to phenotypic selection for breeds originating from their respective regions. This diversity needs to be identified and maintained in the face of progressive Westernization. These populations deserve further study as potential model populations for the evolution of major histocompatibility complex alleles, for the study of canine genetic diversity, for the development of dog breeds and for studies on the comigration of ancestral human and dog populations.

Characterization of MHC-I in the blue tit (Cyanistes caeruleus) reveals low levels of genetic diversity and trans-population evolution across European populations.

PubMed

Schut, Elske; Aguilar, Juan Rivero-de; Merino, Santiago; Magrath, Michael J L; Komdeur, Jan; Westerdahl, Helena

2011-08-01

The major histcompatibility complex (MHC) is a vital component of the adaptive immune system in all vertebrates. This study is the first to characterize MHC class I (MHC-I) in blue tits (Cyanistes caeruleus), and we use MHC-I exon 3 sequence data from individuals originating from three locations across Europe: Spain, the Netherlands to Sweden. Our phylogeny of the 17 blue tit MHC-I alleles contains one allele cluster with low nucleotide diversity compared to the remaining more diverse alleles. We found a significant evidence for balancing selection in the peptide-binding region in the diverse allele group only. No separation according to geographic location was found in the phylogeny of alleles. Although the number of MHC-I loci of the blue tit is comparable to that of other passerine species, the nucleotide diversity of MHC-I appears to be much lower than that of other passerine species, including the closely related great tit (Parus major) and the severely inbred Seychelles warbler (Acrocephalus sechellensis). We believe that this initial MHC-I characterization in blue tits provides an important step towards understanding the mechanisms shaping MHC-I diversity in natural populations.

Role of stochastic processes in maintaining discrete strain structure in antigenically diverse pathogen populations.

PubMed

Buckee, Caroline O; Recker, Mario; Watkins, Eleanor R; Gupta, Sunetra

2011-09-13

Many highly diverse pathogen populations appear to exist stably as discrete antigenic types despite evidence of genetic exchange. It has been shown that this may arise as a consequence of immune selection on pathogen populations, causing them to segregate permanently into discrete nonoverlapping subsets of antigenic variants to minimize competition for available hosts. However, discrete antigenic strain structure tends to break down under conditions where there are unequal numbers of allelic variants at each locus. Here, we show that the inclusion of stochastic processes can lead to the stable recovery of discrete strain structure through loss of certain alleles. This explains how pathogen populations may continue to behave as independently transmitted strains despite inevitable asymmetries in allelic diversity of major antigens. We present evidence for this type of structuring across global meningococcal isolates in three diverse antigens that are currently being developed as vaccine components.

Understanding Genetic Diversity and Population Structure of a Poa pratensis Worldwide Collection through Morphological, Nuclear and Chloroplast Diversity Analysis

PubMed Central

Russi, Luigi; Marconi, Gianpiero; Sharbel, Timothy F.; Veronesi, Fabio; Albertini, Emidio

2015-01-01

Poa pratensis L. is a forage and turf grass species well adapted to a wide range of mesic to moist habitats. Due to its genome complexity little is known regarding evolution, genome composition and intraspecific phylogenetic relationships of this species. In the present study we investigated the morphological and genetic diversity of 33 P. pratensis accessions from 23 different countries using both nuclear and chloroplast molecular markers as well as flow cytometry of somatic tissues. This with the aim of shedding light on the genetic diversity and phylogenetic relationships of the collection that includes both cultivated and wild materials. Morphological characterization showed that the most relevant traits able to distinguish cultivated from wild forms were spring growth habit and leaf colour. The genome size analysis revealed high variability both within and between accessions in both wild and cultivated materials. The sequence analysis of the trnL-F chloroplast region revealed a low polymorphism level that could be the result of the complex mode of reproduction of this species. In addition, a strong reduction of chloroplast SSR variability was detected in cultivated materials, where only two alleles were conserved out of the four present in wild accessions. Contrarily, at nuclear level, high variability exist in the collection where the analysis of 11 SSR loci allowed the detection of a total of 91 different alleles. A Bayesian analysis performed on nuclear SSR data revealed that studied materials belong to two main clusters. While wild materials are equally represented in both clusters, the domesticated forms are mostly belonging to cluster P2 which is characterized by lower genetic diversity compared to the cluster P1. In the Neighbour Joining tree no clear distinction was found between accessions with the exception of those from China and Mongolia that were clearly separated from all the others. PMID:25893249

Analysis of mitochondrial genetic diversity of Ustilago maydis in Mexico.

PubMed

Jiménez-Becerril, María F; Hernández-Delgado, Sanjuana; Solís-Oba, Myrna; González Prieto, Juan M

2018-01-01

The current understanding of the genetic diversity of the phytopathogenic fungus Ustilago maydis is limited. To determine the genetic diversity and structure of U. maydis, 48 fungal isolates were analyzed using mitochondrial simple sequence repeats (SSRs). Tumours (corn smut or 'huitlacoche') were collected from different Mexican states with diverse environmental conditions. Using bioinformatic tools, five microsatellites were identified within intergenic regions of the U. maydis mitochondrial genome. SSRMUM4 was the most polymorphic marker. The most common repeats were hexanucleotides. A total of 12 allelic variants were identified, with a mean of 2.4 alleles per locus. An estimate of the genetic diversity using analysis of molecular variance (AMOVA) revealed that the highest variance component is within states (84%), with moderate genetic differentiation between states (16%) (F ST  = 0.158). A dendrogram generated using the unweighted paired-grouping method with arithmetic averages (UPGMA) and the Bayesian analysis of population structure grouped the U. maydis isolates into two subgroups (K = 2) based on their shared SSRs.

Short mucin 6 alleles are associated with H pylori infection

PubMed Central

Nguyen, Thai V; Janssen, Marcel JR; Gritters, Paulien; te Morsche, René HM; Drenth, Joost PH; van Asten, Henri; Laheij, Robert JF; Jansen, Jan BMJ

2006-01-01

AIM: To investigate the relationship between mucin 6 (MUC6) VNTR length and H pylori infection. METHODS: Blood samples were collected from patients visiting the Can Tho General Hospital for upper gastrointestinal endoscopy. DNA was isolated from whole blood, the repeated section was cut out using a restriction enzyme (PvuII) and the length of the allele fragments was determined by Southern blotting. H pylori infection was diagnosed by 14C urea breath test. For analysis, MUC6 allele fragment length was dichotomized as being either long (> 13.5 kbp) or short (≤ 13.5 kbp) and patients were classified according to genotype [long-long (LL), long-short (LS), short-short (SS)]. RESULTS: 160 patients were studied (mean age 43 years, 36% were males, 58% H pylori positive). MUC6 PvuII-restricted allele fragment lengths ranged from 7 to 19 kbp. Of the patients with the LL, LS, SS MUC6 genotype, 43% (24/56), 57% (25/58) and 76% (11/46) were infected with H pylori, respectively (P = 0.003). CONCLUSION: Short MUC6 alleles are associated with H pylori infection. PMID:17009402

Cultivable bacterial diversity along the altitudinal zonation and vegetation range of tropical Eastern Himalaya.

PubMed

Lyngwi, Nathaniel A; Koijam, Khedarani; Sharma, D; Joshi, S R

2013-03-01

The Northeastern part of India sprawls over an area of 262 379km2 in the Eastern Himalayan range. This constitutes a biodiversity hotspot with high levels of biodiversity and endemism; unfortunately, is also a poorly known area, especially on its microbial diversity. In this study, we assessed cultivable soil bacterial diversity and distribution from lowlands to highlands (34 to 3 990m.a.s.l.). Soil physico-chemical parameters and forest types across the different altitudes were characterized and correlated with bacterial distribution and diversity. Microbes from the soil samples were grown in Nutrient, Muller Hinton and Luria-Bertani agar plates and were initially characterized using biochemical methods. Parameters like dehydrogenase and urease activities, temperature, moisture content, pH, carbon content, bulk density of the sampled soil were measured for each site. Representative isolates were also subjected to 16S rDNA sequence analysis. A total of 155 cultivable bacterial isolates were characterized which were analyzed for richness, evenness and diversity indices. The tropical and sub-tropical forests supported higher bacterial diversity compared to temperate pine, temperate conifer, and sub-alpine rhododendron forests. The 16S rRNA phylogenetic analysis revealed that Firmicutes was the most common group followed by Proteobacreria and Bacteroidetes. Species belonging to the genera Bacillus and Pseudomonas were the most abundant. Bacterial CFU showed positive but insignificant correlation with soil parameters like pH (r=0.208), soil temperature (r=0.303), ambient temperature (r=0.443), soil carbon content (r=0.525), soil bulk density (r=0.268), soil urease (r=0.549) and soil dehydrogenase (r=0.492). Altitude (r=-0.561) and soil moisture content (r=-0.051) showed negative correlation. Altitudinal gradient along with the vegetation and soil physico-chemical parameters were found to influence bacterial diversity and distribution. This study points out that this is

Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landraces and cultivars.

PubMed

Cavanagh, Colin R; Chao, Shiaoman; Wang, Shichen; Huang, Bevan Emma; Stephen, Stuart; Kiani, Seifollah; Forrest, Kerrie; Saintenac, Cyrille; Brown-Guedira, Gina L; Akhunova, Alina; See, Deven; Bai, Guihua; Pumphrey, Michael; Tomar, Luxmi; Wong, Debbie; Kong, Stephan; Reynolds, Matthew; da Silva, Marta Lopez; Bockelman, Harold; Talbert, Luther; Anderson, James A; Dreisigacker, Susanne; Baenziger, Stephen; Carter, Arron; Korzun, Viktor; Morrell, Peter Laurent; Dubcovsky, Jorge; Morell, Matthew K; Sorrells, Mark E; Hayden, Matthew J; Akhunov, Eduard

2013-05-14

Domesticated crops experience strong human-mediated selection aimed at developing high-yielding varieties adapted to local conditions. To detect regions of the wheat genome subject to selection during improvement, we developed a high-throughput array to interrogate 9,000 gene-associated single-nucleotide polymorphisms (SNP) in a worldwide sample of 2,994 accessions of hexaploid wheat including landraces and modern cultivars. Using a SNP-based diversity map we characterized the impact of crop improvement on genomic and geographic patterns of genetic diversity. We found evidence of a small population bottleneck and extensive use of ancestral variation often traceable to founders of cultivars from diverse geographic regions. Analyzing genetic differentiation among populations and the extent of haplotype sharing, we identified allelic variants subjected to selection during improvement. Selective sweeps were found around genes involved in the regulation of flowering time and phenology. An introgression of a wild relative-derived gene conferring resistance to a fungal pathogen was detected by haplotype-based analysis. Comparing selective sweeps identified in different populations, we show that selection likely acts on distinct targets or multiple functionally equivalent alleles in different portions of the geographic range of wheat. The majority of the selected alleles were present at low frequency in local populations, suggesting either weak selection pressure or temporal variation in the targets of directional selection during breeding probably associated with changing agricultural practices or environmental conditions. The developed SNP chip and map of genetic variation provide a resource for advancing wheat breeding and supporting future population genomic and genome-wide association studies in wheat.

Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landraces and cultivars

PubMed Central

Cavanagh, Colin R.; Chao, Shiaoman; Wang, Shichen; Huang, Bevan Emma; Stephen, Stuart; Kiani, Seifollah; Forrest, Kerrie; Saintenac, Cyrille; Brown-Guedira, Gina L.; Akhunova, Alina; See, Deven; Bai, Guihua; Pumphrey, Michael; Tomar, Luxmi; Wong, Debbie; Kong, Stephan; Reynolds, Matthew; da Silva, Marta Lopez; Bockelman, Harold; Talbert, Luther; Anderson, James A.; Dreisigacker, Susanne; Baenziger, Stephen; Carter, Arron; Korzun, Viktor; Morrell, Peter Laurent; Dubcovsky, Jorge; Morell, Matthew K.; Sorrells, Mark E.; Hayden, Matthew J.; Akhunov, Eduard

2013-01-01

Domesticated crops experience strong human-mediated selection aimed at developing high-yielding varieties adapted to local conditions. To detect regions of the wheat genome subject to selection during improvement, we developed a high-throughput array to interrogate 9,000 gene-associated single-nucleotide polymorphisms (SNP) in a worldwide sample of 2,994 accessions of hexaploid wheat including landraces and modern cultivars. Using a SNP-based diversity map we characterized the impact of crop improvement on genomic and geographic patterns of genetic diversity. We found evidence of a small population bottleneck and extensive use of ancestral variation often traceable to founders of cultivars from diverse geographic regions. Analyzing genetic differentiation among populations and the extent of haplotype sharing, we identified allelic variants subjected to selection during improvement. Selective sweeps were found around genes involved in the regulation of flowering time and phenology. An introgression of a wild relative-derived gene conferring resistance to a fungal pathogen was detected by haplotype-based analysis. Comparing selective sweeps identified in different populations, we show that selection likely acts on distinct targets or multiple functionally equivalent alleles in different portions of the geographic range of wheat. The majority of the selected alleles were present at low frequency in local populations, suggesting either weak selection pressure or temporal variation in the targets of directional selection during breeding probably associated with changing agricultural practices or environmental conditions. The developed SNP chip and map of genetic variation provide a resource for advancing wheat breeding and supporting future population genomic and genome-wide association studies in wheat. PMID:23630259

Genetic diversity of the Dwarf honeybee (Apis florea Fabricius, 1787) populations based on microsatellite markers.

PubMed

Asadi, N; Rahimi, A; Ghaheri, M; Kahrizi, D; Bagheri Dehbaghi, M; Khederzadeh, S; Banabazi, M H; Esmaeilkhanian, S; Veisi, B; Geravandi, M; Karim, H; Vaziri, S; Daneshgar, F; Zargooshi, J

2016-10-31

Apis florea is one of two species of small, wild honeybee. The present study was conducted to evaluate the genetic diversity of Apis florea honeybee from 48 nests (colonies) using microsatellite markers in the South of Iran. All honeybee samples were analyzed for six microsatellite loci (A88, A107, A7, B124, A113 and A35). The six loci had different numbers of alleles in the sampled colonies ranging from 7 (loci A107) to 3 (loci A7, A35). Gene diversity in Apis florea ranged from 0.491 to 0.595. This range probably reflects the spreading of nests in a large region with a varied climate. Phylogenetic tree showed two distinct clusters including a) Minab region samples and b) Bandar Abbas, Bandar Khamir and Qeshm Island regions. All of these regions are geographically rich, having varied vegetation and climate conditions. Our findings are an important contribution to the methods of studying distribution and conservation of Apis florea.

Ongoing Horizontal and Vertical Transmission of Virulence Genes and papA Alleles among Escherichia coli Blood Isolates from Patients with Diverse-Source Bacteremia

PubMed Central

Johnson, James R.; O'Bryan, Timothy T.; Kuskowski, Michael; Maslow, Joel N.

2001-01-01

The phylogenetic distributions of multiple putative virulence factors (VFs) and papA (P fimbrial structural subunit) alleles among 182 Escherichia coli blood isolates from patients with diverse-source bacteremia were defined. Phylogenetic correspondence among these strains, the E. coli Reference (ECOR) collection, and other collections of extraintestinal pathogenic E. coli (ExPEC) was assessed. Although among the 182 bacteremia isolates phylogenetic group B2 predominated, exhibited the greatest concentration of individual VFs, and contained the largest number of familiar virulent clones, other phylogenetic groups exhibited greater concentrations of certain VFs than did group B2 and included several additional virulent clones. Certain of the newly detected VF genes, e.g., fyuA (yersiniabactin; 76%) and focG (F1C fimbriae; 25%), were as prevalent or more prevalent than their more familiar traditional counterparts, e.g., iut (aerobactin; 57%) and sfaS (S fimbriae; 14%), thus possibly offering additional useful targets for preventive interventions. Considerable diversity of VF profiles was observed at every level within the phylogenetic tree, including even within individual lineages. This suggested that many different pathways can lead to extraintestinal virulence in E. coli and that the evolution of ExPEC, which involves extensive horizontal transmission of VFs and continuous remodeling of pathogenicity-associated islands, is a highly active, ongoing process. PMID:11500406

Does the parasite-mediated selection drive the MHC class IIB diversity in wild populations of European chub (Squalius cephalus)?

PubMed

Seifertová, Mária; Jarkovský, Jiří; Šimková, Andrea

2016-04-01

The genes of major histocompatibility complex (MHC) provide an excellent opportunity to study host-parasite relationships because they are expected to evolve in response to parasites and variation in parasite communities. In this study, we investigated the potential role of parasite-mediated selection acting on MHC class IIB (DAB) genes in European chub (Squalius cephalus) natural populations. We found significant differences between populations in metazoan parasites, neutral and adaptive genetic diversities. The analyses based on pairwise data revealed that populations with dissimilar MHC allelic profiles were geographically distant populations with significantly different diversity in microsatellites and a dissimilar composition of parasite communities. The results from the generalized estimating equations method (GEE) on the level of individuals revealed that metazoan parasite load in European chub was influenced by the diversity of DAB alleles as well as by the diversity of neutral genetic markers and host traits reflecting condition and immunocompetence. The multivariate co-inertia analysis showed specific associations between DAB alleles and parasite species. DAB1-like alleles were more involved in associations with ectoparasites, while DAB3-like alleles were positively associated with endoparasites which could suggest potential differences between DAB genes caused by different selection pressure. Our study revealed that parasite-mediated selection is not the only variable affecting MHC diversity in European chub; however, we strongly support the role of neutral processes as the main driver of DAB diversity across populations. In addition, our study contributes to the understanding of the evolution of MHC genes in wild living fish.

Intrinsic MYH7 expression regulation contributes to tissue level allelic imbalance in hypertrophic cardiomyopathy.

PubMed

Montag, Judith; Syring, Mandy; Rose, Julia; Weber, Anna-Lena; Ernstberger, Pia; Mayer, Anne-Kathrin; Becker, Edgar; Keyser, Britta; Dos Remedios, Cristobal; Perrot, Andreas; van der Velden, Jolanda; Francino, Antonio; Navarro-Lopez, Francesco; Ho, Carolyn Yung; Brenner, Bernhard; Kraft, Theresia

2017-08-01

HCM, the most common inherited cardiac disease, is mainly caused by mutations in sarcomeric genes. More than a third of the patients are heterozygous for mutations in the MYH7 gene encoding for the β-myosin heavy chain. In HCM-patients, expression of the mutant and the wildtype allele can be unequal, thus leading to fractions of mutant and wildtype mRNA and protein which deviate from 1:1. This so-called allelic imbalance was detected in whole tissue samples but also in individual cells. There is evidence that the severity of HCM not only depends on the functional effect of the mutation itself, but also on the fraction of mutant protein in the myocardial tissue. Allelic imbalance has been shown to occur in a broad range of genes. Therefore, we aimed to examine whether the MYH7-alleles are intrinsically expressed imbalanced or whether the allelic imbalance is solely associated with the disease. We compared the expression of MYH7-alleles in non-HCM donors and in HCM-patients with different MYH7-missense mutations. In the HCM-patients, we identified imbalanced as well as equal expression of both alleles. Also at the protein level, allelic imbalance was determined. Most interestingly, we also discovered allelic imbalance and balance in non-HCM donors. Our findings therefore strongly indicate that apart from mutation-specific mechanisms, also non-HCM associated allelic-mRNA expression regulation may account for the allelic imbalance of the MYH7 gene in HCM-patients. Since the relative amount of mutant mRNA and protein or the extent of allelic imbalance has been associated with the severity of HCM, individual analysis of the MYH7-allelic expression may provide valuable information for the prognosis of each patient.

Genome-wide signatures of flowering adaptation to climate temperature: Regional analyses in a highly diverse native range of Arabidopsis thaliana.

PubMed

Tabas-Madrid, Daniel; Méndez-Vigo, Belén; Arteaga, Noelia; Marcer, Arnald; Pascual-Montano, Alberto; Weigel, Detlef; Xavier Picó, F; Alonso-Blanco, Carlos

2018-03-08

Current global change is fueling an interest to understand the genetic and molecular mechanisms of plant adaptation to climate. In particular, altered flowering time is a common strategy for escape from unfavourable climate temperature. In order to determine the genomic bases underlying flowering time adaptation to this climatic factor, we have systematically analysed a collection of 174 highly diverse Arabidopsis thaliana accessions from the Iberian Peninsula. Analyses of 1.88 million single nucleotide polymorphisms provide evidence for a spatially heterogeneous contribution of demographic and adaptive processes to geographic patterns of genetic variation. Mountains appear to be allele dispersal barriers, whereas the relationship between flowering time and temperature depended on the precise temperature range. Environmental genome-wide associations supported an overall genome adaptation to temperature, with 9.4% of the genes showing significant associations. Furthermore, phenotypic genome-wide associations provided a catalogue of candidate genes underlying flowering time variation. Finally, comparison of environmental and phenotypic genome-wide associations identified known (Twin Sister of FT, FRIGIDA-like 1, and Casein Kinase II Beta chain 1) and new (Epithiospecifer Modifier 1 and Voltage-Dependent Anion Channel 5) genes as candidates for adaptation to climate temperature by altered flowering time. Thus, this regional collection provides an excellent resource to address the spatial complexity of climate adaptation in annual plants. © 2018 John Wiley & Sons Ltd.

Allelic variation of the Lyme disease spirochete adhesin DbpA influences spirochetal binding to decorin, dermatan sulfate, and mammalian cells.

PubMed

Benoit, Vivian M; Fischer, Joshua R; Lin, Yi-Pin; Parveen, Nikhat; Leong, John M

2011-09-01

After transmission by an infected tick, the Lyme disease spirochete, Borrelia burgdorferi sensu lato, colonizes the mammalian skin and may disseminate systemically. The three major species of Lyme disease spirochete--B. burgdorferi sensu stricto, B. garinii, and B. afzelii--are associated with different chronic disease manifestations. Colonization is likely promoted by the ability to bind to target tissues, and Lyme disease spirochetes utilize multiple adhesive molecules to interact with diverse mammalian components. The allelic variable surface lipoprotein decorin binding protein A (DbpA) promotes bacterial binding to the proteoglycan decorin and to the glycosaminoglycan (GAG) dermatan sulfate. To assess allelic variation of DbpA in GAG-, decorin-, and cell-binding activities, we expressed dbpA alleles derived from diverse Lyme disease spirochetes in B. burgdorferi strain B314, a noninfectious and nonadherent strain that lacks dbpA. Each DbpA allele conferred upon B. burgdorferi strain B314 the ability to bind to cultured kidney epithelial (but not glial or endothelial) cells, as well as to purified decorin and dermatan sulfate. Nevertheless, allelic variation of DbpA was associated with dramatic differences in substrate binding activity. In most cases, decorin and dermatan sulfate binding correlated well, but DbpA of B. afzelii strain VS461 promoted differential binding to decorin and dermatan sulfate, indicating that the two activities are separable. DbpA from a clone of B. burgdorferi strain N40 that can cause disseminated infection in mice displayed relatively low adhesive activity, indicating that robust DbpA-mediated adhesive activity is not required for spread in the mammalian host.

Genetic exchange of fimbrial alleles exemplifies the adaptive virulence strategy of Porphyromonas gingivalis.

PubMed

Kerr, Jennifer E; Abramian, Jared R; Dao, Doan-Hieu V; Rigney, Todd W; Fritz, Jamie; Pham, Tan; Gay, Isabel; Parthasarathy, Kavitha; Wang, Bing-yan; Zhang, Wenjian; Tribble, Gena D

2014-01-01

Porphyromonas gingivalis is a gram-negative anaerobic bacterium, a member of the human oral microbiome, and a proposed "keystone" pathogen in the development of chronic periodontitis, an inflammatory disease of the gingiva. P. gingivalis is a genetically diverse species, and is able to exchange chromosomal DNA between strains by natural competence and conjugation. In this study, we investigate the role of horizontal DNA transfer as an adaptive process to modify behavior, using the major fimbriae as our model system, due to their critical role in mediating interactions with the host environment. We show that P. gingivalis is able to exchange fimbrial allele types I and IV into four distinct strain backgrounds via natural competence. In all recombinants, we detected a complete exchange of the entire fimA allele, and the rate of exchange varies between the different strain backgrounds. In addition, gene exchange within other regions of the fimbrial genetic locus was identified. To measure the biological implications of these allele swaps we compared three genotypes of fimA in an isogenic background, strain ATCC 33277. We demonstrate that exchange of fimbrial allele type results in profound phenotypic changes, including the quantity of fimbriae elaborated, membrane blebbing, auto-aggregation and other virulence-associated phenotypes. Replacement of the type I allele with either the type III or IV allele resulted in increased invasion of gingival fibroblast cells relative to the isogenic parent strain. While genetic variability is known to impact host-microbiome interactions, this is the first study to quantitatively assess the adaptive effect of exchanging genes within the pan genome cloud. This is significant as it presents a potential mechanism by which opportunistic pathogens may acquire the traits necessary to modify host-microbial interactions.

Genetic Stability and Evolution of the sigB Allele, Used for Listeria Sensu Stricto Subtyping and Phylogenetic Inference

PubMed Central

Liao, Jingqiu; Wiedmann, Martin

2017-01-01

ABSTRACT Sequencing of single genes remains an important tool that allows the rapid classification of bacteria. Sequencing of a portion of sigB, which encodes a stress-responsive alternative sigma factor, has emerged as a commonly used molecular tool for the initial characterization of diverse Listeria isolates. In this study, evolutionary approaches were used to assess the validity of sigB allelic typing for Listeria. For a data set of 4,280 isolates, sigB allelic typing showed a Simpson's index of diversity of 0.96. Analyses of 164 sigB allelic types (ATs) found among the 6 Listeria sensu stricto species, representing these 4,280 isolates, indicate that neither frequent homologous recombination nor positive selection significantly contributed to the evolution of sigB, confirming its genetic stability. The molecular clock test provided evidence for unequal evolution rates across clades; Listeria welshimeri displayed the lowest sigB diversity and was the only species in which sigB evolved in a clocklike manner, implying a unique natural history. Among the four L. monocytogenes lineages, sigB evolution followed a molecular clock only in lineage IV. Moreover, sigB displayed a significant negative Tajima D value in lineage II, suggesting a recent population bottleneck followed by lineage expansion. The absence of positive selection along with the violation of the molecular clock suggested a nearly neutral mechanism of Listeria sensu stricto sigB evolution. While comparison with a whole-genome sequence-based phylogeny revealed that the sigB phylogeny did not correctly reflect the ancestry of L. monocytogenes lineage IV, the availability of a large sigB AT database allowed accurate species classification. IMPORTANCE sigB allelic typing has been widely used for species delineation and subtyping of Listeria. However, an informative evaluation of this method from an evolutionary perspective was missing. Our data indicate that the genetic stability of sigB is affected by

A series of no isthmus (noi) alleles of the zebrafish pax2.1 gene reveals multiple signaling events in development of the midbrain-hindbrain boundary.

PubMed

Lun, K; Brand, M

1998-08-01

Generation of cell diversity in the vertebrate central nervous system starts during gastrulation stages in the ectodermal germ layer and involves specialized cell groups, such as the organizer located at the midbrain-hindbrain boundary (MHB). Mutations in the zebrafish no isthmus (noi) gene alter development of the MHB, and affect the pax2.1 gene (formerly pax(zf-b)). Analysis of the structure of pax2.1 reveals at least 12 normal splice variants. The noi alleles can be arranged, by molecular and phenotypic criteria, into a series of five alleles of differing strength, ranging from a null allele to weak alleles. In keeping with a role in development of the MHB organizer, gene expression is already affected in the MHB primordium of the gastrula neural ectoderm in noi mutants. eng3 activation is completely and eng2 activation is strongly dependent on noi function. In contrast, onset of wnt1, fgf8 and her5 expression occurs normally in the null mutants, but is eliminated later on. Our observations suggest that three signaling pathways, involving pax2.1, wnt1 and fgf8, are activated independently in early anterior-posterior patterning of this area. In addition, analysis of the allelic series unexpectedly suggests that noi activity is also required during dorsal-ventral patterning of the MHB in somitogenesis stages, and possibly in a later eng expression phase. We propose that noi/pax2.1 participates in sequential signaling processes as a key integrator of midbrain-hindbrain boundary development.

Promoting Utilization of Saccharum spp. Genetic Resources through Genetic Diversity Analysis and Core Collection Construction

PubMed Central

Pathak, Bhuvan; Ayala-Silva, Tomas; Yang, Xiping; Todd, James; Glynn, Neil C.; Kuhn, David N.; Glaz, Barry; Gilbert, Robert A.; Comstock, Jack C.; Wang, Jianping

2014-01-01

Sugarcane (Saccharum spp.) and other members of Saccharum spp. are attractive biofuel feedstocks. One of the two World Collections of Sugarcane and Related Grasses (WCSRG) is in Miami, FL. This WCSRG has 1002 accessions, presumably with valuable alleles for biomass, other important agronomic traits, and stress resistance. However, the WCSRG has not been fully exploited by breeders due to its lack of characterization and unmanageable population. In order to optimize the use of this genetic resource, we aim to 1) genotypically evaluate all the 1002 accessions to understand its genetic diversity and population structure and 2) form a core collection, which captures most of the genetic diversity in the WCSRG. We screened 36 microsatellite markers on 1002 genotypes and recorded 209 alleles. Genetic diversity of the WCSRG ranged from 0 to 0.5 with an average of 0.304. The population structure analysis and principal coordinate analysis revealed three clusters with all S. spontaneum in one cluster, S. officinarum and S. hybrids in the second cluster and mostly non-Saccharum spp. in the third cluster. A core collection of 300 accessions was identified which captured the maximum genetic diversity of the entire WCSRG which can be further exploited for sugarcane and energy cane breeding. Sugarcane and energy cane breeders can effectively utilize this core collection for cultivar improvement. Further, the core collection can provide resources for forming an association panel to evaluate the traits of agronomic and commercial importance. PMID:25333358

Inference of genetic diversity in popcorn S3 progenies.

PubMed

Pena, G F; do Amaral, A T; Ribeiro, R M; Ramos, H C C; Boechat, M S B; Santos, J S; Mafra, G S; Kamphorst, S H; de Lima, V J; Vivas, M; de Souza Filho, G A

2016-05-09

Molecular markers are a useful tool for identification of complementary heterotic groups in breeding programs aimed at the production of superior hybrids, particularly for crops such as popcorn in which heterotic groups are not well-defined. The objective of the present study was to analyze the genetic diversity of 47 genotypes of tropical popcorn to identify possible heterotic groups for the development of superior hybrids. Four genotypes of high genetic value were studied: hybrid IAC 125, strain P2, and varieties UENF 14 and BRS Angela. In addition, 43 endogamous S3 progenies obtained from variety UENF 14 were used. Twenty-five polymorphic SSR-EST markers were analyzed. A genetic distance matrix was obtained and the following molecular diversity parameters were estimated: number of alleles, number of effective alleles, polymorphism information content (PIC), observed and expected heterozygosities, Shannon diversity index, and coefficient of inbreeding. We found a moderate PIC and high diversity index, indicating that the studied population presents both good discriminatory ability and high informativeness for the utilized markers. The dendrogram built based on the dissimilarity matrix indicated six distinct groups. Our findings demonstrate the genetic diversity among the evaluated genotypes and provide evidence for heterotic groups in popcorn. Furthermore, the functional genetic diversity indicates that there are informative genetic markers for popcorn.

Genetic Diversity of Aromatic Rice Germplasm Revealed By SSR Markers.

PubMed

Jasim Aljumaili, Saba; Rafii, M Y; Latif, M A; Sakimin, Siti Zaharah; Arolu, Ibrahim Wasiu; Miah, Gous

2018-01-01

Aromatic rice cultivars constitute a small but special group of rice and are considered the best in terms of quality and aroma. Aroma is one of the most significant quality traits of rice, and variety with aroma has a higher price in the market. This research was carried out to study the genetic diversity among the 50 aromatic rice accessions from three regions (Peninsular Malaysia, Sabah, and Sarawak) with 3 released varieties as a control using the 32 simple sequence repeat (SSR) markers. The objectives of this research were to quantify the genetic divergence of aromatic rice accessions using SSR markers and to identify the potential accessions for introgression into the existing rice breeding program. Genetic diversity index among the three populations such as Shannon information index ( I ) ranged from 0.25 in control to 0.98 in Sabah population. The mean numbers of effective alleles and Shannon's information index were 0.36 and 64.90%, respectively. Similarly, the allelic diversity was very high with mean expected heterozygosity ( H e ) of 0.60 and mean Nei's gene diversity index of 0.36. The dendrogram based on UPGMA and Nei's genetic distance classified the 53 rice accessions into 10 clusters. Analysis of molecular variance (AMOVA) revealed that 89% of the total variation observed in this germplasm came from within the populations, while 11% of the variation emanated among the populations. These results reflect the high genetic differentiation existing in this aromatic rice germplasm. Using all these criteria and indices, seven accessions (Acc9993, Acc6288, Acc6893, Acc7580, Acc6009, Acc9956, and Acc11816) from three populations have been identified and selected for further evaluation before introgression into the existing breeding program and for future aromatic rice varietal development.

Genetic Diversity of Aromatic Rice Germplasm Revealed By SSR Markers

PubMed Central

Jasim Aljumaili, Saba; Sakimin, Siti Zaharah; Arolu, Ibrahim Wasiu; Miah, Gous

2018-01-01

Aromatic rice cultivars constitute a small but special group of rice and are considered the best in terms of quality and aroma. Aroma is one of the most significant quality traits of rice, and variety with aroma has a higher price in the market. This research was carried out to study the genetic diversity among the 50 aromatic rice accessions from three regions (Peninsular Malaysia, Sabah, and Sarawak) with 3 released varieties as a control using the 32 simple sequence repeat (SSR) markers. The objectives of this research were to quantify the genetic divergence of aromatic rice accessions using SSR markers and to identify the potential accessions for introgression into the existing rice breeding program. Genetic diversity index among the three populations such as Shannon information index (I) ranged from 0.25 in control to 0.98 in Sabah population. The mean numbers of effective alleles and Shannon's information index were 0.36 and 64.90%, respectively. Similarly, the allelic diversity was very high with mean expected heterozygosity (He) of 0.60 and mean Nei's gene diversity index of 0.36. The dendrogram based on UPGMA and Nei's genetic distance classified the 53 rice accessions into 10 clusters. Analysis of molecular variance (AMOVA) revealed that 89% of the total variation observed in this germplasm came from within the populations, while 11% of the variation emanated among the populations. These results reflect the high genetic differentiation existing in this aromatic rice germplasm. Using all these criteria and indices, seven accessions (Acc9993, Acc6288, Acc6893, Acc7580, Acc6009, Acc9956, and Acc11816) from three populations have been identified and selected for further evaluation before introgression into the existing breeding program and for future aromatic rice varietal development. PMID:29736396

Estimated allele substitution effects underlying genomic evaluation models depend on the scaling of allele counts.

PubMed

Bouwman, Aniek C; Hayes, Ben J; Calus, Mario P L

2017-10-30

Genomic evaluation is used to predict direct genomic values (DGV) for selection candidates in breeding programs, but also to estimate allele substitution effects (ASE) of single nucleotide polymorphisms (SNPs). Scaling of allele counts influences the estimated ASE, because scaling of allele counts results in less shrinkage towards the mean for low minor allele frequency (MAF) variants. Scaling may become relevant for estimating ASE as more low MAF variants will be used in genomic evaluations. We show the impact of scaling on estimates of ASE using real data and a theoretical framework, and in terms of power, model fit and predictive performance. In a dairy cattle dataset with 630 K SNP genotypes, the correlation between DGV for stature from a random regression model using centered allele counts (RRc) and centered and scaled allele counts (RRcs) was 0.9988, whereas the overall correlation between ASE using RRc and RRcs was 0.27. The main difference in ASE between both methods was found for SNPs with a MAF lower than 0.01. Both the ratio (ASE from RRcs/ASE from RRc) and the regression coefficient (regression of ASE from RRcs on ASE from RRc) were much higher than 1 for low MAF SNPs. Derived equations showed that scenarios with a high heritability, a large number of individuals and a small number of variants have lower ratios between ASE from RRc and RRcs. We also investigated the optimal scaling parameter [from - 1 (RRcs) to 0 (RRc) in steps of 0.1] in the bovine stature dataset. We found that the log-likelihood was maximized with a scaling parameter of - 0.8, while the mean squared error of prediction was minimized with a scaling parameter of - 1, i.e., RRcs. Large differences in estimated ASE were observed for low MAF SNPs when allele counts were scaled or not scaled because there is less shrinkage towards the mean for scaled allele counts. We derived a theoretical framework that shows that the difference in ASE due to shrinkage is heavily influenced by the

A survey of FRAXE allele sizes in three populations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, N.; Ju, W.; Curley, D.

1996-08-09

FRAXE is a fragile site located at Xq27-8, which contains polymorphic triplet GCC repeats associated with a CpG island. Similar to FRAXA, expansion of the GCC repeats results in an abnormal methylation of the CpG island and is associated with a mild mental retardation syndrome (FRAXE-MR). We surveyed the GCC repeat alleles of FRAXE from 3 populations. A total of 665 X chromosomes including 416 from a New York Euro-American sample (259 normal and 157 with FRAXA mutations), 157 from a Chinese sample (144 normal and 13 FRAXA), and 92 from a Finnish sample (56 normal and 36 FRAXA) weremore » analyzed by polymerase chain reaction. Twenty-seven alleles, ranging from 4 to 39 GCC repeats, were observed. The modal repeat number was 16 in the New York and Finnish samples and accounted for 24% of all the chromosomes tested (162/665). The modal repeat number in the Chinese sample was 18. A founder effect for FRAXA was suggested among the Finnish FRAXA samples in that 75% had the FRAXE 16 repeat allele versus only 30% of controls. Sequencing of the FRAXE region showed no imperfections within the GCC repeat region, such as those commonly seen in FRAXA. The smaller size and limited range of repeats and the lack of imperfections suggests the molecular mechanisms underlying FRAXE triplet mutations may be different from those underlying FRAXA. 27 refs., 4 figs., 1 tab.« less

Genetic diversity of Plasmodium falciparum merozoite surface protein-1 (block 2), glutamate-rich protein and sexual stage antigen Pfs25 from Chandigarh, North India.

PubMed

Kaur, Hargobinder; Sehgal, Rakesh; Goyal, Kapil; Makkar, Nikita; Yadav, Richa; Bharti, Praveen K; Singh, Neeru; Sarmah, Nilanju P; Mohapatra, Pradyumna K; Mahanta, Jagadish; Bansal, Devendra; Sultan, Ali A; Kanwar, Jagat R

2017-12-01

To elucidate the genetic diversity of Plasmodium falciparum in residual transmission foci of northern India. Clinically suspected patients with malaria were screened for malaria infection by microscopy. 48 P. falciparum-infected patients were enrolled from tertiary care hospital in Chandigarh, India. Blood samples were collected from enrolled patients, genomic DNA extraction and nested PCR was performed for further species confirmation. Sanger sequencing was carried out using block 2 region of msp1, R2 region of glurp and pfs25-specific primers. Extensive diversity was found in msp1 alleles with predominantly RO33 alleles. Overall allelic prevalence was 55.8% for RO33, 39.5% for MAD20 and 4.7% for K1. Six variants were observed in MAD20, whereas no variant was found in RO33 and K1 alleles. A phylogenetic analysis of RO33 alleles indicated more similarity to South African isolates, whereas MAD20 alleles showed similarity with South-East Asian isolates. In glurp, extensive variation was observed with eleven different alleles based on the AAU repeats. However, pfs25 showed less diversity and was the most stable among the targeted genes. Our findings document the genetic diversity among circulating strains of P. falciparum in an area of India with low malaria transmission and could have implications for control strategies to reach the national goal of malaria elimination. © 2017 John Wiley & Sons Ltd.

Genetic diversity and population structure among six cattle breeds in South Africa using a whole genome SNP panel

PubMed Central

Makina, Sithembile O.; Muchadeyi, Farai C.; van Marle-Köster, Este; MacNeil, Michael D.; Maiwashe, Azwihangwisi

2014-01-01

Information about genetic diversity and population structure among cattle breeds is essential for genetic improvement, understanding of environmental adaptation as well as utilization and conservation of cattle breeds. This study investigated genetic diversity and the population structure among six cattle breeds in South African (SA) including Afrikaner (n = 44), Nguni (n = 54), Drakensberger (n = 47), Bonsmara (n = 44), Angus (n = 31), and Holstein (n = 29). Genetic diversity within cattle breeds was analyzed using three measures of genetic diversity namely allelic richness (AR), expected heterozygosity (He) and inbreeding coefficient (f). Genetic distances between breed pairs were evaluated using Nei's genetic distance. Population structure was assessed using model-based clustering (ADMIXTURE). Results of this study revealed that the allelic richness ranged from 1.88 (Afrikaner) to 1.73 (Nguni). Afrikaner cattle had the lowest level of genetic diversity (He = 0.24) and the Drakensberger cattle (He = 0.30) had the highest level of genetic variation among indigenous and locally-developed cattle breeds. The level of inbreeding was lower across the studied cattle breeds. As expected the average genetic distance was the greatest between indigenous cattle breeds and Bos taurus cattle breeds but the lowest among indigenous and locally-developed breeds. Model-based clustering revealed some level of admixture among indigenous and locally-developed breeds and supported the clustering of the breeds according to their history of origin. The results of this study provided useful insight regarding genetic structure of SA cattle breeds. PMID:25295053

Genetic diversity and population structure among six cattle breeds in South Africa using a whole genome SNP panel.

PubMed

Makina, Sithembile O; Muchadeyi, Farai C; van Marle-Köster, Este; MacNeil, Michael D; Maiwashe, Azwihangwisi

2014-01-01

Information about genetic diversity and population structure among cattle breeds is essential for genetic improvement, understanding of environmental adaptation as well as utilization and conservation of cattle breeds. This study investigated genetic diversity and the population structure among six cattle breeds in South African (SA) including Afrikaner (n = 44), Nguni (n = 54), Drakensberger (n = 47), Bonsmara (n = 44), Angus (n = 31), and Holstein (n = 29). Genetic diversity within cattle breeds was analyzed using three measures of genetic diversity namely allelic richness (AR), expected heterozygosity (He) and inbreeding coefficient (f). Genetic distances between breed pairs were evaluated using Nei's genetic distance. Population structure was assessed using model-based clustering (ADMIXTURE). Results of this study revealed that the allelic richness ranged from 1.88 (Afrikaner) to 1.73 (Nguni). Afrikaner cattle had the lowest level of genetic diversity (He = 0.24) and the Drakensberger cattle (He = 0.30) had the highest level of genetic variation among indigenous and locally-developed cattle breeds. The level of inbreeding was lower across the studied cattle breeds. As expected the average genetic distance was the greatest between indigenous cattle breeds and Bos taurus cattle breeds but the lowest among indigenous and locally-developed breeds. Model-based clustering revealed some level of admixture among indigenous and locally-developed breeds and supported the clustering of the breeds according to their history of origin. The results of this study provided useful insight regarding genetic structure of SA cattle breeds.

Insight into the Diversity of Penicillin-Binding Protein 2x Alleles and Mutations in Viridans Streptococci

PubMed Central

van der Linden, Mark; Otten, Julia; Bergmann, Carina; Latorre, Cristina; Liñares, Josefina

2017-01-01

ABSTRACT The identification of commensal streptococci species is an everlasting problem due to their ability to genetically transform. A new challenge in this respect is the recent description of Streptococcus pseudopneumoniae as a new species, which was distinguished from closely related pathogenic S. pneumoniae and commensal S. mitis by a variety of physiological and molecular biological tests. Forty-one atypical S. pneumoniae isolates have been collected at the German National Reference Center for Streptococci (GNRCS). Multilocus sequence typing (MLST) confirmed 35 isolates as the species S. pseudopneumoniae. A comparison with the pbp2x sequences from 120 commensal streptococci isolated from different continents revealed that pbp2x is distinct among penicillin-susceptible S. pseudopneumoniae isolates. Four penicillin-binding protein x (PBPx) alleles of penicillin-sensitive S. mitis account for most of the diverse sequence blocks in resistant S. pseudopneumoniae, S. pneumoniae, and S. mitis, and S. infantis and S. oralis sequences were found in S. pneumoniae from Japan. PBP2x genes of the family of mosaic genes related to pbp2x in the S. pneumoniae clone Spain23F-1 were observed in S. oralis and S. infantis as well, confirming its global distribution. Thirty-eight sites were altered within the PBP2x transpeptidase domains of penicillin-resistant strains, excluding another 37 sites present in the reference genes of sensitive strains. Specific mutational patterns were detected depending on the parental sequence blocks, in agreement with distinct mutational pathways during the development of beta-lactam resistance. The majority of the mutations clustered around the active site, whereas others are likely to affect stability or interactions with the C-terminal domain or partner proteins. PMID:28193649

Silage Collected from Dairy Farms Harbors an Abundance of Listeriaphages with Considerable Host Range and Genome Size Diversity

PubMed Central

Vongkamjan, Kitiya; Switt, Andrea Moreno; den Bakker, Henk C.; Fortes, Esther D.

2012-01-01

Since the food-borne pathogen Listeria monocytogenes is common in dairy farm environments, it is likely that phages infecting this bacterium (“listeriaphages”) are abundant on dairy farms. To better understand the ecology and diversity of listeriaphages on dairy farms and to develop a diverse phage collection for further studies, silage samples collected on two dairy farms were screened for L. monocytogenes and listeriaphages. While only 4.5% of silage samples tested positive for L. monocytogenes, 47.8% of samples were positive for listeriaphages, containing up to >1.5 × 104 PFU/g. Host range characterization of the 114 phage isolates obtained, with a reference set of 13 L. monocytogenes strains representing the nine major serotypes and four lineages, revealed considerable host range diversity; phage isolates were classified into nine lysis groups. While one serotype 3c strain was not lysed by any phage isolates, serotype 4 strains were highly susceptible to phages and were lysed by 63.2 to 88.6% of phages tested. Overall, 12.3% of phage isolates showed a narrow host range (lysing 1 to 5 strains), while 28.9% of phages represented broad host range (lysing ≥11 strains). Genome sizes of the phage isolates were estimated to range from approximately 26 to 140 kb. The extensive host range and genomic diversity of phages observed here suggest an important role of phages in the ecology of L. monocytogenes on dairy farms. In addition, the phage collection developed here has the potential to facilitate further development of phage-based biocontrol strategies (e.g., in silage) and other phage-based tools. PMID:23042180

Development of simple sequence repeat markers and diversity analysis in alfalfa (Medicago sativa L.).

PubMed

Wang, Zan; Yan, Hongwei; Fu, Xinnian; Li, Xuehui; Gao, Hongwen

2013-04-01

Efficient and robust molecular markers are essential for molecular breeding in plant. Compared to dominant and bi-allelic markers, multiple alleles of simple sequence repeat (SSR) markers are particularly informative and superior in genetic linkage map and QTL mapping in autotetraploid species like alfalfa. The objective of this study was to enrich SSR markers directly from alfalfa expressed sequence tags (ESTs). A total of 12,371 alfalfa ESTs were retrieved from the National Center for Biotechnology Information. Total 774 SSR-containing ESTs were identified from 716 ESTs. On average, one SSR was found per 7.7 kb of EST sequences. Tri-nucleotide repeats (48.8 %) was the most abundant motif type, followed by di-(26.1 %), tetra-(11.5 %), penta-(9.7 %), and hexanucleotide (3.9 %). One hundred EST-SSR primer pairs were successfully designed and 29 exhibited polymorphism among 28 alfalfa accessions. The allele number per marker ranged from two to 21 with an average of 6.8. The PIC values ranged from 0.195 to 0.896 with an average of 0.608, indicating a high level of polymorphism of the EST-SSR markers. Based on the 29 EST-SSR markers, assessment of genetic diversity was conducted and found that Medicago sativa ssp. sativa was clearly different from the other subspecies. The high transferability of those EST-SSR markers was also found for relative species.

Evaluation of 16 SNPs allele-specific to quantify post hSCT chimerism by SYBR green-based qRT-PCR.

PubMed

Almeida, Carlos Arthur Cardoso; Dreyfuss, Juliana Luporini; Azevedo-Shimmoto, Marily Maria; Figueiredo, Maria Stela; de Oliveira, José Salvador Rodrigues

2013-03-01

The importance of monitoring post haematopoietic stem cell transplantation (hSCT) chimerism has been defined in numerous publications. Single-nucleotide polymorphisms (SNPs) are molecular markers that vary significantly among different populations. Allied to a very sensible technique, SNP assays seem to be very sensitive (0.001%) when post hSCT chimerism is measured. However, well known SNP frequencies are limited to certain populations, mainly in countries where there is a high level of diversity in its population, therefore restricting their use worldwide. Amplification by SYBR green based quantitative real time PCR of eight pairs of allele-specific SNPs (MLH-1, PECAM-1, ICAM-1, SUR-1, HA-1, rs715405, rs713503, rs2296600) was conducted in 88 patient/donor pairs, who underwent allogeneic myeloablative or non-myeloablative hSCT. One informative allele was detected in at least 42% (n=37) of the samples; 20% (n=18) had at least two informative alleles; 10% (n=9) had at least three informative alleles; 9% (n=8) had more than three informative alleles and 18% (n=16) showed no informative allele at all. Overall, the frequency of informative alleles for these SNPs in the Brazilian population was very low. Consequently, the amount of information attained reached 9% of those expected, being able to discriminate only eight pairs of donor/recipient samples with more than three informative alleles, making them useless for the quantification of chimerism in our routine.

Characterization of bovine MHC DRB3 diversity in Latin American Creole cattle breeds.

PubMed

Giovambattista, Guillermo; Takeshima, Shin-nosuke; Ripoli, Maria Veronica; Matsumoto, Yuki; Franco, Luz Angela Alvarez; Saito, Hideki; Onuma, Misao; Aida, Yoko

2013-04-25

In cattle, bovine leukocyte antigens (BoLAs) have been extensively used as markers for diseases and immunological traits. However, none of the highly adapted Latin American Creole breeds have been characterized for BoLA gene polymorphism by high resolution typing methods. In this work, we sequenced exon 2 of the BoLA class II DRB3 gene from 179 cattle (113 Bolivian Yacumeño cattle and 66 Colombian Hartón del Valle cattle breeds) using a polymerase chain reaction sequence-based typing (PCR-SBT) method. We identified 36 previously reported alleles and three novel alleles. Thirty-five (32 reported and three new) and 24 alleles (22 reported and two new) were detected in Yacumeño and Hartón del Valle breeds, respectively. Interestingly, Latin American Creole cattle showed a high degree of gene diversity despite their small population sizes, and 10 alleles including three new alleles were found only in these two Creole breeds. We next compared the degree of genetic variability at the population and sequence levels and the genetic distance in the two breeds with those previously reported in five other breeds: Holstein, Japanese Shorthorn, Japanese Black, Jersey, and Hanwoo. Both Creole breeds presented gene diversity higher than 0.90, a nucleotide diversity higher than 0.07, and mean number of pairwise differences higher than 19, indicating that Creole cattle had similar genetic diversity at BoLA-DRB3 to the other breeds. A neutrality test showed that the high degree of genetic variability may be maintained by balancing selection. The FST index and the exact G test showed significant differences across all cattle populations (FST=0.0478; p<0.001). Results from the principal components analysis and the phylogenetic tree showed that Yacumeño and Hartón del Valle breeds were closely related to each other. Collectively, our results suggest that the high level of genetic diversity could be explained by the multiple origins of the Creole germplasm (European, African and

Discovery, distribution and diversity of Puroindoline-D1 genes in bread wheat from five countries (Triticum aestivum L.)

PubMed Central

2013-01-01

Background Grain texture is one of the most important characteristics in bread wheat (Triticum aestivum L.). Puroindoline-D1 genes play the main role in controlling grain texture and are intimately associated with the milling and processing qualities in bread wheat. Results A series of diagnostic molecular markers and dCAPS markers were used to characterize Pina-D1 and Pinb-D1 in 493 wheat cultivars from diverse geographic locations. A primer walking strategy was used to characterize PINA-null alleles at the DNA level. Results indicated that Chinese landraces encompassing 12 different Puroindoline-D1 allelic combinations showed the highest diversity, while CIMMYT wheat cultivars containing 3 different Puroindoline-D1 allelic combinations showed the lowest diversity amongst wheat cultivars from the five countries surveyed. Two novel Pina-D1 alleles, designated Pina-D1s with a 4,422-bp deletion and Pina-D1u with a 6,460-bp deletion in the Ha (Hardness) locus, were characterized at the DNA level by a primer walking strategy, and corresponding molecular markers Pina-N3 and Pina-N4 were developed for straightforward identification of the Pina-D1s and Pina-D1u alleles. Analysis of the association of Puroindoline-D1 alleles with grain texture indicated that wheat cultivars with Pina-null/Pinb-null allele, possessing an approximate 33-kb deletion in the Ha locus, have the highest SKCS hardness index amongst the different genotypes used in this study. Moreover, wheat cultivars with the PINA-null allele have significantly higher SKCS hardness index than those of Pinb-D1b and Pinb-D1p alleles. Conclusions Molecular characterization of the Puroindoline-D1 allele was investigated in bread wheat cultivars from five geographic regions, resulting in the discovery of two new alleles - Pina-D1s and Pina-D1u. Molecular markers were developed for both alleles. Analysis of the association of the Puroindoline-D1 alleles with grain texture showed that cultivars with PINA-null allele

Identification, genealogical structure and population genetics of S-alleles in Malus sieversii, the wild ancestor of domesticated apple.

PubMed

Ma, X; Cai, Z; Liu, W; Ge, S; Tang, L

2017-09-01

The self-incompatibility (SI) gene that is specifically expressed in pistils encodes the SI-associated ribonuclease (S-RNase), functioning as the female-specificity determinant of a gametophytic SI system. Despite extensive surveys in Malus domestica, the S-alleles have not been fully investigated for Malus sieversii, the primary wild ancestor of the domesticated apple. Here we screened the M. sieversii S-alleles via PCR amplification and sequencing, and identified 14 distinct alleles in this species. By contrast, nearly 40 are present in its close wild relative, Malus sylvestris. We further sequenced 8 nuclear genes to provide a neutral reference, and investigated the evolution of S-alleles via genealogical and population genetic analyses. Both shared ancestral polymorphism and an excess of non-synonymous substitution were detected in the S-RNases of the tribe Maleae in Rosaceae, indicating the action of long-term balancing selection. Approximate Bayesian Computations based on the reference neutral loci revealed a severe bottleneck in four of the six studied M. sieversii populations, suggesting that the low number of S-alleles found in this species is mainly the result of diversity loss due to a drastic population contraction. Such a bottleneck may lead to ambiguous footprints of ongoing balancing selection detected at the S-locus. This study not only elucidates the constituents and number of S-alleles in M. sieversii but also illustrates the potential utility of S-allele number shifts in demographic inference for self-incompatible plant species.

Relative frequencies of DRB1*11 alleles and their DRB3 associations in five major population groups in a United States bone marrow registry.

PubMed

Tang, T F; Huang, A Y; Pappas, A; Slack, R; Ng, J; Hartzman, R J; Hurley, C K

2000-08-01

One hundred sixty-one individuals from each of five US population groups, Caucasians (CAU), African Americans (AFA), Asians/Pacific Islanders (API), Hispanics (HIS), and Native Americans (NAT), were randomly selected from a volunteer bone marrow registry database consisting of 14,452 HLA-DRB1*11 positive individuals. This sampling provided at least an 80% probability of detecting a rare allele that occurred at 1% in the DRB1*11 positive population. Samples were typed for DRB1*11 alleles by polymerase chain reaction-sequence specific oligonucleotide probe typing (PCR-SSOP). A total of 10 DRB1*11 alleles out of 27 possible alleles were detected. The distribution and diversity of DRB1*11 alleles varied among populations although DRB1*1101 was the predominant DRB1*11 allele in all populations. Caucasians were the least diversified; only four common alleles (DRB1*1101-*1104) were observed. As well as the four common alleles, other groups also carried one or two other less frequent alleles including DRB1*1105 (API), *1106 (API), *1110 (AFA), *1114 (HIS), *1115 (NAT), and *1117 (AFA). A subset (418) of these individuals were also typed for DRB3 alleles. Most (97.6%) showed a strong association of DRB1*11 with DRB3*0202.

Molecular genetic diversity and population structure of Ethiopian white lupin landraces: Implications for breeding and conservation.

PubMed

Atnaf, Mulugeta; Yao, Nasser; Martina, Kyalo; Dagne, Kifle; Wegary, Dagne; Tesfaye, Kassahun

2017-01-01

White lupin is one of the four economically important species of the Lupinus genus and is an important grain legume in the Ethiopian farming system. However, there has been limited research effort to characterize the Ethiopian white lupin landraces. Fifteen polymorphic simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of 212 Ethiopian white lupin (Lupinus albus) landraces and two genotypes from different species (Lupinus angustifolius and Lupinus mutabilis) were used as out-group. The SSR markers revealed 108 different alleles, 98 of them from 212 landraces and 10 from out-group genotypes, with an average of 6.5 alleles per locus. The average gene diversity was 0.31. Twenty eight landraces harbored one or more private alleles from the total of 28 private alleles identified in the 212 white lupin accessions. Seventy-seven rare alleles with a frequency of less than 5% were identified and accounted for 78.6% of the total alleles detected. Analysis of molecular variance (AMOVA) showed that 92% of allelic diversity was attributed to individual accessions within populations while only 8% was distributed among populations. At 70% similarity level, the UPGMA dendrogram resulted in the formation of 13 clusters comprised of 2 to 136 landraces, with the out-group genotypes and five landraces remaining distinct and ungrouped. Population differentiation and genetic distance were relatively high between Gondar and Ethiopian white lupin populations collected by Australians. A model-based population structure analysis divided the white lupin landraces into two populations. All Ethiopian white lupin landrace populations, except most of the landraces collected by Australians (77%) and about 44% from Awi, were grouped together with significant admixtures. The study also suggested that 34 accessions, as core collections, were sufficient to retain 100% of SSR diversity. These accessions (core G-34) represent 16% of the whole 212

Molecular genetic diversity and population structure of Ethiopian white lupin landraces: Implications for breeding and conservation

PubMed Central

Yao, Nasser; Martina, Kyalo; Dagne, Kifle; Wegary, Dagne; Tesfaye, Kassahun

2017-01-01

White lupin is one of the four economically important species of the Lupinus genus and is an important grain legume in the Ethiopian farming system. However, there has been limited research effort to characterize the Ethiopian white lupin landraces. Fifteen polymorphic simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of 212 Ethiopian white lupin (Lupinus albus) landraces and two genotypes from different species (Lupinus angustifolius and Lupinus mutabilis) were used as out-group. The SSR markers revealed 108 different alleles, 98 of them from 212 landraces and 10 from out-group genotypes, with an average of 6.5 alleles per locus. The average gene diversity was 0.31. Twenty eight landraces harbored one or more private alleles from the total of 28 private alleles identified in the 212 white lupin accessions. Seventy-seven rare alleles with a frequency of less than 5% were identified and accounted for 78.6% of the total alleles detected. Analysis of molecular variance (AMOVA) showed that 92% of allelic diversity was attributed to individual accessions within populations while only 8% was distributed among populations. At 70% similarity level, the UPGMA dendrogram resulted in the formation of 13 clusters comprised of 2 to 136 landraces, with the out-group genotypes and five landraces remaining distinct and ungrouped. Population differentiation and genetic distance were relatively high between Gondar and Ethiopian white lupin populations collected by Australians. A model-based population structure analysis divided the white lupin landraces into two populations. All Ethiopian white lupin landrace populations, except most of the landraces collected by Australians (77%) and about 44% from Awi, were grouped together with significant admixtures. The study also suggested that 34 accessions, as core collections, were sufficient to retain 100% of SSR diversity. These accessions (core G-34) represent 16% of the whole 212

Seed fates in crop-wild hybrid sunflower: crop allele and maternal effects.

PubMed

Pace, Brian A; Alexander, Helen M; Emry, Jason D; Mercer, Kristin L

2015-02-01

Domestication has resulted in selection upon seed traits found in wild populations, yet crop-wild hybrids retain some aspects of both parental phenotypes. Seed fates of germination, dormancy, and mortality can influence the success of crop allele introgression in crop-wild hybrid zones, especially if crop alleles or crop-imparted seed coverings result in out-of-season germination. We performed a seed burial experiment using crop, wild, and diverse hybrid sunflower (Helianthus annuus) cross types to test how a cross type's maternal parent and nuclear genetic composition might affect its fate under field conditions. We observed higher maladaptive fall germination in the crop- and F1- produced seeds than wild-produced seeds and, due to an interaction with percent crop alleles, fall germination was higher for cross types with more crop-like nuclear genetics. By spring, crop-produced cross types had the highest overwintering mortality, primarily due to higher fall germination. Early spring germination was identical across maternal types, but germination continued for F1-produced seeds. In conclusion, the more wild-like the maternal parent or the less proportion of the cross type's genome contributed by the crop, the greater likelihood a seed will remain ungerminated than die. Wild-like dormancy may facilitate introgression through future recruitment from the soil seed bank.

Bacterial diversity in faeces from polar bear (Ursus maritimus) in Arctic Svalbard.

PubMed

Glad, Trine; Bernhardsen, Pål; Nielsen, Kaare M; Brusetti, Lorenzo; Andersen, Magnus; Aars, Jon; Sundset, Monica A

2010-01-14

Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81 degrees N, 10-33 degrees E). In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006. A 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70%) were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 x 10(4) to 1.6 x 10(6) colony forming units (cfu)/ml for the rectum swabs and 4.0 x 10(3) to 1.0 x 10(5) cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic beta-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears. The bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations.

Bacterial diversity in faeces from polar bear (Ursus maritimus) in Arctic Svalbard

PubMed Central

2010-01-01

Background Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81°N, 10-33°E). In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006. Results A 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70%) were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 × 104 to 1.6 × 106 colony forming units (cfu)/ml for the rectum swabs and 4.0 × 103 to 1.0 × 105 cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic β-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears. Conclusion The bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations. PMID:20074323

Allele-specific cytokine responses at the HLA-C locus: implications for psoriasis.

PubMed

Hundhausen, Christian; Bertoni, Anna; Mak, Rose K; Botti, Elisabetta; Di Meglio, Paola; Clop, Alex; Laggner, Ute; Chimenti, Sergio; Hayday, Adrian C; Barker, Jonathan N; Trembath, Richard C; Capon, Francesca; Nestle, Frank O

2012-03-01

Psoriasis is an inflammatory skin disorder that is inherited as a complex trait. Genetic studies have repeatedly highlighted HLA-C as the major determinant for psoriasis susceptibility, with the Cw*0602 allele conferring significant disease risk in a wide range of populations. Despite the potential importance of HLA-C variation in psoriasis, either via an effect on peptide presentation or immuno-inhibitory activity, allele-specific expression patterns have not been investigated. Here, we used reporter assays to characterize two regulatory variants, which virtually abolished the response to tumor necrosis factor (TNF)-α (rs2524094) and IFN-γ (rs10657191) in HLA-Cw*0602 and a cluster of related alleles. We validated these findings through the analysis of HLA-Cw*0602 expression in primary keratinocytes treated with TNF-α and IFN-γ. Finally, we showed that HLA-Cw*0602 transcripts are not increased in psoriatic skin lesions, despite highly elevated TNF-α levels. Thus, our findings demonstrate the presence of allele-specific differences in HLA-C expression and indicate that HLA-Cw*0602 is unresponsive to upregulation by key proinflammatory cytokines in psoriasis. These data pave the way for functional studies into the pathogenic role of the major psoriasis susceptibility allele.

Allele-specific cytokine responses at the HLA-C locus, implications for psoriasis

PubMed Central

Hundhausen, Christian; Bertoni, Anna; Mak, Rose K; Botti, Elisabetta; Di Meglio, Paola; Clop, Alex; Laggner, Ute; Chimenti, Sergio; Hayday, Adrian C; Barker, Jonathan N; Trembath, Richard C; Capon, Francesca; Nestle, Frank O

2011-01-01

Psoriasis is an inflammatory skin disorder that is inherited as a complex trait. Genetic studies have repeatedly highlighted HLA-C as the major determinant for psoriasis susceptibility, with the Cw*0602 allele conferring significant disease risk in a wide-range of populations. Despite the potential importance of HLA-C variation in psoriasis, either via an effect on peptide presentation or immuno-inhibitory activity, allele-specific expression patterns have not been investigated. Here, we used reporter assays to characterize two regulatory variants, which virtually abolished the response to TNF-α (rs2524094) and IFN-γ (rs10657191) in HLA-Cw*0602 and a cluster of related alleles. We validated these findings through the analysis of HLA-Cw*0602 expression in primary keratinocytes treated with TNF-α and IFN-γ. Finally, we showed that HLA-Cw*0602 transcripts are not increased in psoriatic skin lesions, despite highly elevated TNF-α levels. Thus, our findings demonstrate the presence of allele-specific differences in HLA-C expression and indicate that HLA-Cw*0602 is unresponsive to up-regulation by key pro-inflammatory cytokines in psoriasis. These data pave the way for functional studies into the pathogenic role of the major psoriasis susceptibility allele. PMID:22113476

The effect of wild card designations and rare alleles in forensic DNA database searches.

PubMed

Tvedebrink, Torben; Bright, Jo-Anne; Buckleton, John S; Curran, James M; Morling, Niels

2015-05-01

Forensic DNA databases are powerful tools used for the identification of persons of interest in criminal investigations. Typically, they consist of two parts: (1) a database containing DNA profiles of known individuals and (2) a database of DNA profiles associated with crime scenes. The risk of adventitious or chance matches between crimes and innocent people increases as the number of profiles within a database grows and more data is shared between various forensic DNA databases, e.g. from different jurisdictions. The DNA profiles obtained from crime scenes are often partial because crime samples may be compromised in quantity or quality. When an individual's profile cannot be resolved from a DNA mixture, ambiguity is introduced. A wild card, F, may be used in place of an allele that has dropped out or when an ambiguous profile is resolved from a DNA mixture. Variant alleles that do not correspond to any marker in the allelic ladder or appear above or below the extent of the allelic ladder range are assigned the allele designation R for rare allele. R alleles are position specific with respect to the observed/unambiguous allele. The F and R designations are made when the exact genotype has not been determined. The F and R designation are treated as wild cards for searching, which results in increased chance of adventitious matches. We investigated the probability of adventitious matches given these two types of wild cards. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Genetic Diversity of the Two Commercial Tetraploid Cotton Species in the Gossypium Diversity Reference Set.

PubMed

Hinze, Lori L; Gazave, Elodie; Gore, Michael A; Fang, David D; Scheffler, Brian E; Yu, John Z; Jones, Don C; Frelichowski, James; Percy, Richard G

2016-05-01

A diversity reference set has been constructed for the Gossypium accessions in the US National Cotton Germplasm Collection to facilitate more extensive evaluation and utilization of accessions held in the Collection. A set of 105 mapped simple sequence repeat markers was used to study the allelic diversity of 1933 tetraploid Gossypium accessions representative of the range of diversity of the improved and wild accessions of G. hirsutum and G. barbadense. The reference set contained 410 G. barbadense accessions and 1523 G. hirsutum accessions. Observed numbers of polymorphic and private bands indicated a greater diversity in G. hirsutum as compared to G. barbadense as well as in wild-type accessions as compared to improved accessions in both species. The markers clearly differentiated the 2 species. Patterns of diversity within species were observed but not clearly delineated, with much overlap occurring between races and regions of origin for wild accessions and between historical and geographic breeding pools for cultivated accessions. Although the percentage of accessions showing introgression was higher among wild accessions than cultivars in both species, the average level of introgression within individual accessions, as indicated by species-specific bands, was much higher in wild accessions of G. hirsutum than in wild accessions of G. barbadense. The average level of introgression within individual accessions was higher in improved G. barbadense cultivars than in G. hirsutum cultivars. This molecular characterization reveals the levels and distributions of genetic diversity that will allow for better exploration and utilization of cotton genetic resources. Published by Oxford University Press on behalf of the American Genetic Association 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

PubMed Central

Gout, Lilian; Eckert, Maria; Rouxel, Thierry; Balesdent, Marie-Hélène

2006-01-01

Leptosphaeria maculans is the most ubiquitous fungal pathogen of Brassica crops and causes the devastating stem canker disease of oilseed rape worldwide. We used minisatellite markers to determine the genetic structure of L. maculans in four field populations from France. Isolates were collected at three different spatial scales (leaf, 2-m2 field plot, and field) enabling the evaluation of spatial distribution of the mating type alleles and of genetic variability within and among field populations. Within each field population, no gametic disequilibrium between the minisatellite loci was detected and the mating type alleles were present at equal frequencies. Both sexual and asexual reproduction occur in the field, but the genetic structure of these populations is consistent with annual cycles of randomly mating sexual reproduction. All L. maculans field populations had a high level of gene diversity (H = 0.68 to 0.75) and genotypic diversity. Within each field population, the number of genotypes often was very close to the number of isolates. Analysis of molecular variance indicated that >99.5% of the total genetic variability was distributed at a small spatial scale, i.e., within 2-m2 field plots. Population differentiation among the four field populations was low (GST < 0.02), suggesting a high degree of gene exchange between these populations. The high gene flow evidenced here in French populations of L. maculans suggests a rapid countrywide diffusion of novel virulence alleles whenever novel resistance sources are used. PMID:16391041

Genetic Diversity of the Endangered Neotropical Cichlid Fish (Gymnogeophagus setequedas) in Brazil.

PubMed

Souza-Shibatta, Lenice; Kotelok-Diniz, Thais; Ferreira, Dhiego G; Shibatta, Oscar A; Sofia, Silvia H; de Assumpção, Lucileine; Pini, Suelen F R; Makrakis, Sergio; Makrakis, Maristela C

2018-01-01

Gymnogeophagus setequedas is a rare and rheophilic species of tribe Geophagini, considered endangered in Brazilian red lists. Its previously known geographical distribution range was the Paraná River basin, in Paraguay, and a tributary of the Itaipu Reservoir in Brazil. Since its description no specimens have been collected in the original known distribution area. However, recent records of G. setequedas in the lower Iguaçu River, in a region considered highly endemic for the ichthyofauna, extended the known geographical distribution and may represent one of the last remnants of the species. The aim of this study was to estimate the genetic diversity and population structure of G. setequedas , using microsatellite markers and mitochondrial haplotypes, in order to test the hypothesis of low genetic diversity in this restricted population. Muscular tissue samples of 86 specimens were obtained from nine locations in the Lower Iguaçu River basin, between upstream of the Iguaçu Falls and downstream of the Salto Caxias Reservoir. Seven microsatellites loci were examined and a total of 120 different alleles were obtained. The number of alleles per locus ( N A ) was 17.429, effective alleles ( N E ) 6.644, expected heterozygosity ( H E ) 0.675, observed ( H O ) heterozygosity 0.592, and inbreeding coefficient ( F IS ) 0.128. Twelve haplotypes in the D-Loop region were revealed, with values of h (0.7642) and π (0.00729), suggesting a large and stable population with a long evolutionary history. Thus, both molecular markers revealed high levels of genetic diversity and indicated the occurrence of a single G. setequedas population distributed along a stretch of approximately 200 km. The pattern of mismatch distribution was multimodal, which is usually ascribed to populations in demographic equilibrium. Nevertheless, the construction of a new hydroelectric power plant, already underway between the Salto Caxias Reservoir and Iguaçu Falls, could fragment this population

Genetic Diversity of the Endangered Neotropical Cichlid Fish (Gymnogeophagus setequedas) in Brazil

PubMed Central

Souza-Shibatta, Lenice; Kotelok-Diniz, Thais; Ferreira, Dhiego G.; Shibatta, Oscar A.; Sofia, Silvia H.; de Assumpção, Lucileine; Pini, Suelen F. R.; Makrakis, Sergio; Makrakis, Maristela C.

2018-01-01

Gymnogeophagus setequedas is a rare and rheophilic species of tribe Geophagini, considered endangered in Brazilian red lists. Its previously known geographical distribution range was the Paraná River basin, in Paraguay, and a tributary of the Itaipu Reservoir in Brazil. Since its description no specimens have been collected in the original known distribution area. However, recent records of G. setequedas in the lower Iguaçu River, in a region considered highly endemic for the ichthyofauna, extended the known geographical distribution and may represent one of the last remnants of the species. The aim of this study was to estimate the genetic diversity and population structure of G. setequedas, using microsatellite markers and mitochondrial haplotypes, in order to test the hypothesis of low genetic diversity in this restricted population. Muscular tissue samples of 86 specimens were obtained from nine locations in the Lower Iguaçu River basin, between upstream of the Iguaçu Falls and downstream of the Salto Caxias Reservoir. Seven microsatellites loci were examined and a total of 120 different alleles were obtained. The number of alleles per locus (NA) was 17.429, effective alleles (NE) 6.644, expected heterozygosity (HE) 0.675, observed (HO) heterozygosity 0.592, and inbreeding coefficient (FIS) 0.128. Twelve haplotypes in the D-Loop region were revealed, with values of h (0.7642) and π (0.00729), suggesting a large and stable population with a long evolutionary history. Thus, both molecular markers revealed high levels of genetic diversity and indicated the occurrence of a single G. setequedas population distributed along a stretch of approximately 200 km. The pattern of mismatch distribution was multimodal, which is usually ascribed to populations in demographic equilibrium. Nevertheless, the construction of a new hydroelectric power plant, already underway between the Salto Caxias Reservoir and Iguaçu Falls, could fragment this population, causing loss of

Evolutionary dynamics of sporophytic self-incompatibility alleles in plants.

PubMed

Schierup, M H; Vekemans, X; Christiansen, F B

1997-10-01

The stationary frequency distribution and allelic dynamics in finite populations are analyzed through stochastic simulations in three models of single-locus, multi-allelic sporophytic self-incompatibility. The models differ in the dominance relationships among alleles. In one model, alleles act codominantly in both pollen and style (SSIcod), in the second, alleles form a dominance hierarchy in pollen and style (SSIdom). In the third model, alleles interact codominantly in the style and form a dominance hierarchy in the pollen (SSIdomcod). The SSIcod model behaves similarly to the model of gametophytic self-incompatibility, but the selection intensity is stronger. With dominance, dominant alleles invade the population more easily than recessive alleles and have a lower frequency at equilibrium. In the SSIdom model, recessive alleles have both a higher allele frequency and higher expected life span. In the SSIdomcod model, however, loss due to drift occurs more easily for pollen-recessive than for pollen-dominant alleles, and therefore, dominant alleles have a higher expected life span than the more recessive alleles. The process of allelic turnover in the SSIdomcod and SSIdom models is closely approximated by a random walk on a dominance ladder. Implications of the results for experimental studies of sporophytic self-incompatibility in natural populations are discussed.

Evaluation of genetic diversity in Piper spp using RAPD and SRAP markers.

PubMed

Jiang, Y; Liu, J-P

2011-11-29

Random amplified polymorphic DNA (RAPD) and sequence-related amplified polymorphism (SRAP) analysis were applied to 74 individual plants of Piper spp in Hainan Island. The results showed that the SRAP technique may be more informative and more efficient and effective for studying genetic diversity of Piper spp than the RAPD technique. The overall level of genetic diversity among Piper spp in Hainan was relatively high, with the mean Shannon diversity index being 0.2822 and 0.2909, and the mean Nei's genetic diversity being 0.1880 and 0.1947, calculated with RAPD and SRAP data, respectively. The ranges of the genetic similarity coefficient were 0.486-0.991 and 0.520-1.000 for 74 individual plants of Piper spp (the mean genetic distance was 0.505 and 0.480) and the within-species genetic distance ranged from 0.063 to 0.291 and from 0.096 to 0.234, estimated with RAPD and SRAP data, respectively. These genetic indices indicated that these species are closely related genetically. The dendrogram generated with the RAPD markers was topologically different from the dendrogram based on SRAP markers, but the SRAP technique clearly distinguished all Piper spp from each other. Evaluation of genetic variation levels of six populations showed that the effective number of alleles, Nei's gene diversity and the Shannon information index within Jianfengling and Diaoluoshan populations are higher than those elsewhere; consequently conservation of wild resources of Piper in these two regions should have priority.

Allele frequency data of 15 autosomal STR loci in four major population groups of South Africa.

PubMed

Lucassen, Anton; Ehlers, Karen; Grobler, Paul J; Shezi, Adeline L

2014-03-01

Allele frequency distributions for 15 tetrameric short tandem repeat (STR) loci were determined using the AmpFlSTR® Identifiler Plus™ PCR amplification kit. There was little evidence of departures from Hardy-Weinberg equilibrium or association of alleles of different loci in the population samples. The probability of identity values for the different populations range from 1/3.3 × 10(17) (White) to 1/1.88 × 10(18) (Coloured). The combined probability of paternal exclusion for the different population groups ranges from 0.9995858 (Coloured) to 0.9997874 (Indian).

Genetic Stability and Evolution of the sigB Allele, Used for Listeria Sensu Stricto Subtyping and Phylogenetic Inference.

PubMed

Liao, Jingqiu; Wiedmann, Martin; Kovac, Jasna

2017-06-15

Sequencing of single genes remains an important tool that allows the rapid classification of bacteria. Sequencing of a portion of sigB , which encodes a stress-responsive alternative sigma factor, has emerged as a commonly used molecular tool for the initial characterization of diverse Listeria isolates. In this study, evolutionary approaches were used to assess the validity of sigB allelic typing for Listeria For a data set of 4,280 isolates, sigB allelic typing showed a Simpson's index of diversity of 0.96. Analyses of 164 sigB allelic types (ATs) found among the 6 Listeria sensu stricto species, representing these 4,280 isolates, indicate that neither frequent homologous recombination nor positive selection significantly contributed to the evolution of sigB , confirming its genetic stability. The molecular clock test provided evidence for unequal evolution rates across clades; Listeria welshimeri displayed the lowest sigB diversity and was the only species in which sigB evolved in a clocklike manner, implying a unique natural history. Among the four L. monocytogenes lineages, sigB evolution followed a molecular clock only in lineage IV. Moreover, sigB displayed a significant negative Tajima D value in lineage II, suggesting a recent population bottleneck followed by lineage expansion. The absence of positive selection along with the violation of the molecular clock suggested a nearly neutral mechanism of Listeria sensu stricto sigB evolution. While comparison with a whole-genome sequence-based phylogeny revealed that the sigB phylogeny did not correctly reflect the ancestry of L. monocytogenes lineage IV, the availability of a large sigB AT database allowed accurate species classification. IMPORTANCE sigB allelic typing has been widely used for species delineation and subtyping of Listeria However, an informative evaluation of this method from an evolutionary perspective was missing. Our data indicate that the genetic stability of sigB is affected by neither

European Invasion of North American Pinus strobus at Large and Fine Scales: High Genetic Diversity and Fine-Scale Genetic Clustering over Time in the Adventive Range

PubMed Central

Mandák, Bohumil; Hadincová, Věroslava; Mahelka, Václav; Wildová, Radka

2013-01-01

Background North American Pinus strobus is a highly invasive tree species in Central Europe. Using ten polymorphic microsatellite loci we compared various aspects of the large-scale genetic diversity of individuals from 30 sites in the native distribution range with those from 30 sites in the European adventive distribution range. To investigate the ascertained pattern of genetic diversity of this intercontinental comparison further, we surveyed fine-scale genetic diversity patterns and changes over time within four highly invasive populations in the adventive range. Results Our data show that at the large scale the genetic diversity found within the relatively small adventive range in Central Europe, surprisingly, equals the diversity found within the sampled area in the native range, which is about thirty times larger. Bayesian assignment grouped individuals into two genetic clusters separating North American native populations from the European, non-native populations, without any strong genetic structure shown over either range. In the case of the fine scale, our comparison of genetic diversity parameters among the localities and age classes yielded no evidence of genetic diversity increase over time. We found that SGS differed across age classes within the populations under study. Old trees in general completely lacked any SGS, which increased over time and reached its maximum in the sapling stage. Conclusions Based on (1) the absence of difference in genetic diversity between the native and adventive ranges, together with the lack of structure in the native range, and (2) the lack of any evidence of any temporal increase in genetic diversity at four highly invasive populations in the adventive range, we conclude that population amalgamation probably first happened in the native range, prior to introduction. In such case, there would have been no need for multiple introductions from previously isolated populations, but only several introductions from

Clustering of Genetically Defined Allele Classes in the Caenorhabditis elegans DAF-2 Insulin/IGF-1 Receptor

PubMed Central

Patel, Dhaval S.; Garza-Garcia, Acely; Nanji, Manoj; McElwee, Joshua J.; Ackerman, Daniel; Driscoll, Paul C.; Gems, David

2008-01-01

The DAF-2 insulin/IGF-1 receptor regulates development, metabolism, and aging in the nematode Caenorhabditis elegans. However, complex differences among daf-2 alleles complicate analysis of this gene. We have employed epistasis analysis, transcript profile analysis, mutant sequence analysis, and homology modeling of mutant receptors to understand this complexity. We define an allelic series of nonconditional daf-2 mutants, including nonsense and deletion alleles, and a putative null allele, m65. The most severe daf-2 alleles show incomplete suppression by daf-18(0) and daf-16(0) and have a range of effects on early development. Among weaker daf-2 alleles there exist distinct mutant classes that differ in epistatic interactions with mutations in other genes. Mutant sequence analysis (including 11 newly sequenced alleles) reveals that class 1 mutant lesions lie only in certain extracellular regions of the receptor, while class 2 (pleiotropic) and nonconditional missense mutants have lesions only in the ligand-binding pocket of the receptor ectodomain or the tyrosine kinase domain. Effects of equivalent mutations on the human insulin receptor suggest an altered balance of intracellular signaling in class 2 alleles. These studies consolidate and extend our understanding of the complex genetics of daf-2 and its underlying molecular biology. PMID:18245374

Mutation intolerant genes and targets of FMRP are enriched for nonsynonymous alleles in schizophrenia.

PubMed

Leonenko, Ganna; Richards, Alexander L; Walters, James T; Pocklington, Andrew; Chambert, Kimberly; Al Eissa, Mariam M; Sharp, Sally I; O'Brien, Niamh L; Curtis, David; Bass, Nicholas J; McQuillin, Andrew; Hultman, Christina; Moran, Jennifer L; McCarroll, Steven A; Sklar, Pamela; Neale, Benjamin M; Holmans, Peter A; Owen, Michael J; Sullivan, Patrick F; O'Donovan, Michael C

2017-10-01

Risk of schizophrenia is conferred by alleles occurring across the full spectrum of frequencies from common SNPs of weak effect through to ultra rare alleles, some of which may be moderately to highly penetrant. Previous studies have suggested that some of the risk of schizophrenia is attributable to uncommon alleles represented on Illumina exome arrays. Here, we present the largest study of exomic variation in schizophrenia to date, using samples from the United Kingdom and Sweden (10,011 schizophrenia cases and 13,791 controls). Single variants, genes, and gene sets were analyzed for association with schizophrenia. No single variant or gene reached genome-wide significance. Among candidate gene sets, we found significant enrichment for rare alleles (minor allele frequency [MAF] < 0.001) in genes intolerant of loss-of-function (LoF) variation and in genes whose messenger RNAs bind to fragile X mental retardation protein (FMRP). We further delineate the genetic architecture of schizophrenia by excluding a role for uncommon exomic variants (0.01 ≤ MAF ≥ 0.001) that confer a relatively large effect (odds ratio [OR] > 4). We also show risk alleles within this frequency range exist, but confer smaller effects and should be identified by larger studies. © 2017 Wiley Periodicals, Inc.

Antibiotics reduce genetic diversity of core species in the honeybee gut microbiome.

PubMed

Raymann, Kasie; Bobay, Louis-Marie; Moran, Nancy A

2018-04-01

The gut microbiome plays a key role in animal health, and perturbing it can have detrimental effects. One major source of perturbation to microbiomes, in humans and human-associated animals, is exposure to antibiotics. Most studies of how antibiotics affect the microbiome have used amplicon sequencing of highly conserved 16S rRNA sequences, as in a recent study showing that antibiotic treatment severely alters the species-level composition of the honeybee gut microbiome. But because the standard 16S rRNA-based methods cannot resolve closely related strains, strain-level changes could not be evaluated. To address this gap, we used amplicon sequencing of protein-coding genes to assess effects of antibiotics on fine-scale genetic diversity of the honeybee gut microbiota. We followed the population dynamics of alleles within two dominant core species of the bee gut community, Gilliamella apicola and Snodgrassella alvi, following antibiotic perturbation. Whereas we observed a large reduction in genetic diversity in G. apicola, S. alvi diversity was mostly unaffected. The reduction in G. apicola diversity accompanied an increase in the frequency of several alleles, suggesting resistance to antibiotic treatment. We find that antibiotic perturbation can cause major shifts in diversity and that the extent of these shifts can vary substantially across species. Thus, antibiotics impact not only species composition, but also allelic diversity within species, potentially affecting hosts if variants with particular functions are reduced or eliminated. Overall, we show that amplicon sequencing of protein-coding genes, without clustering into operational taxonomic units, provides an accurate picture of the fine-scale dynamics of microbial communities over time. © 2017 John Wiley & Sons Ltd.

Microsatellite variation and rare alleles in a bottlenecked Hawaiian Islands endemic: implications for reintroductions

USGS Publications Warehouse

Reynolds, Michelle H.; Pearce, John M.; Lavretsky, Philip; Seixas, Pedro P.; Courtot, Karen

2015-01-01

Conservation of genetic biodiversity in endangered wildlife populations is an important challenge to address since the loss of alleles and genetic drift may influence future adaptability. Reintroduction aims to re-establish species to restored or protected ecosystems; however, moving a subset of individuals may result in loss of gene variants during the management-induced bottleneck (i.e. translocation). The endangered Laysan teal Anas laysanensis was once widespread across the Hawaiian archipelago, but became isolated on Laysan Island (415 ha) from the mid-1800s until 2004 when a translocation to Midway Atoll (596 ha) was undertaken to reduce extinction risks. We compared genetic diversity and quantified variation at microsatellite loci sampled from 230 individuals from the wild populations at Laysan (1999 to 2009) and Midway (2007 to 2010; n = 133 Laysan, n = 96 Midway birds). We identified polymorphic markers by screening nuclear microsatellites (N = 83). Low nuclear variation was detected, consistent with the species’ insular isolation and historical bottleneck. Six of 83 microsatellites were polymorphic. We found limited but similar estimates of allelic richness (2.58 alleles per locus) and heterozygosity within populations. However, 2 rare alleles found in the Laysan source population were not present in Midway’s reintroduced population, and a unique allele was discovered in an individual on Midway. Differentiation between island populations was low (FST = 0.6%), but statistically significant. Our results indicate that genetic drift had little effect on offspring generations 3 to 6 yr post-release and demonstrate the utility of using known founder events to help quantify genetic capture during translocations and to inform management decisions.

Allelic genealogies in sporophytic self-incompatibility systems in plants.

PubMed

Schierup, M H; Vekemans, X; Christiansen, F B

1998-11-01

Expectations for the time scale and structure of allelic genealogies in finite populations are formed under three models of sporophytic self-incompatibility. The models differ in the dominance interactions among the alleles that determine the self-incompatibility phenotype: In the SSIcod model, alleles act codominantly in both pollen and style, in the SSIdom model, alleles form a dominance hierarchy, and in SSIdomcod, alleles are codominant in the style and show a dominance hierarchy in the pollen. Coalescence times of alleles rarely differ more than threefold from those under gametophytic self-incompatibility, and transspecific polymorphism is therefore expected to be equally common. The previously reported directional turnover process of alleles in the SSIdomcod model results in coalescence times lower and substitution rates higher than those in the other models. The SSIdom model assumes strong asymmetries in allelic action, and the most recessive extant allele is likely to be the most recent common ancestor. Despite these asymmetries, the expected shape of the allele genealogies does not deviate markedly from the shape of a neutral gene genealogy. The application of the results to sequence surveys of alleles, including interspecific comparisons, is discussed.

A Maximum-Likelihood Method to Correct for Allelic Dropout in Microsatellite Data with No Replicate Genotypes

PubMed Central

Wang, Chaolong; Schroeder, Kari B.; Rosenberg, Noah A.

2012-01-01

Allelic dropout is a commonly observed source of missing data in microsatellite genotypes, in which one or both allelic copies at a locus fail to be amplified by the polymerase chain reaction. Especially for samples with poor DNA quality, this problem causes a downward bias in estimates of observed heterozygosity and an upward bias in estimates of inbreeding, owing to mistaken classifications of heterozygotes as homozygotes when one of the two copies drops out. One general approach for avoiding allelic dropout involves repeated genotyping of homozygous loci to minimize the effects of experimental error. Existing computational alternatives often require replicate genotyping as well. These approaches, however, are costly and are suitable only when enough DNA is available for repeated genotyping. In this study, we propose a maximum-likelihood approach together with an expectation-maximization algorithm to jointly estimate allelic dropout rates and allele frequencies when only one set of nonreplicated genotypes is available. Our method considers estimates of allelic dropout caused by both sample-specific factors and locus-specific factors, and it allows for deviation from Hardy–Weinberg equilibrium owing to inbreeding. Using the estimated parameters, we correct the bias in the estimation of observed heterozygosity through the use of multiple imputations of alleles in cases where dropout might have occurred. With simulated data, we show that our method can (1) effectively reproduce patterns of missing data and heterozygosity observed in real data; (2) correctly estimate model parameters, including sample-specific dropout rates, locus-specific dropout rates, and the inbreeding coefficient; and (3) successfully correct the downward bias in estimating the observed heterozygosity. We find that our method is fairly robust to violations of model assumptions caused by population structure and by genotyping errors from sources other than allelic dropout. Because the data sets

Genetic diversity of Plasmodium falciparum populations in southeast and western Myanmar.

PubMed

Soe, Than Naing; Wu, Yanrui; Tun, Myo Win; Xu, Xin; Hu, Yue; Ruan, Yonghua; Win, Aung Ye Naung; Nyunt, Myat Htut; Mon, Nan Cho Nwe; Han, Kay Thwe; Aye, Khin Myo; Morris, James; Su, Pincan; Yang, Zhaoqing; Kyaw, Myat Phone; Cui, Liwang

2017-07-04

The genetic diversity of malaria parasites reflects the complexity and size of the parasite populations. This study was designed to explore the genetic diversity of Plasmodium falciparum populations collected from two southeastern areas (Shwekyin and Myawaddy bordering Thailand) and one western area (Kyauktaw bordering Bangladesh) of Myanmar. A total of 267 blood samples collected from patients with acute P. falciparum infections during 2009 and 2010 were used for genotyping at the merozoite surface protein 1 (Msp1), Msp2 and glutamate-rich protein (Glurp) loci. One hundred and eighty four samples were successfully genotyped at three genes. The allelic distributions of the three genes were all significantly different among three areas. MAD20 and 3D7 were the most prevalent alleles in three areas for Msp1 and Msp2, respectively. The Glurp allele with a bin size of 700-750 bp was the most prevalent both in Shwekyin and Myawaddy, whereas two alleles with bin sizes of 800-850 bp and 900-1000 bp were the most prevalent in the western site Kyauktaw. Overall, 73.91% of samples contained multiclonal infections, resulting in a mean multiplicity of infection (MOI) of 1.94. Interestingly, the MOI level presented a rising trend with the order of Myawaddy, Kyauktaw and Shwekyin, which also paralleled with the increasing frequencies of Msp1 RO33 and Msp2 FC27 200-250 bp alleles. Msp1 and Msp2 genes displayed higher levels of diversity and higher MOI rates than Glurp. PCR revealed four samples (two from Shwekyin and two from Myawaddy) with mixed infections of P. falciparum and P. vivax. This study genotyped parasite clinical samples from two southeast regions and one western state of Myanmar at the Msp1, Msp2 and Glurp loci, which revealed high levels of genetic diversity and mixed-strain infections of P. falciparum populations at these sites. The results indicated that malaria transmission intensity in these regions remained high and more strengthened control efforts are

sGD: software for estimating spatially explicit indices of genetic diversity.

PubMed

Shirk, A J; Cushman, S A

2011-09-01

Anthropogenic landscape changes have greatly reduced the population size, range and migration rates of many terrestrial species. The small local effective population size of remnant populations favours loss of genetic diversity leading to reduced fitness and adaptive potential, and thus ultimately greater extinction risk. Accurately quantifying genetic diversity is therefore crucial to assessing the viability of small populations. Diversity indices are typically calculated from the multilocus genotypes of all individuals sampled within discretely defined habitat patches or larger regional extents. Importantly, discrete population approaches do not capture the clinal nature of populations genetically isolated by distance or landscape resistance. Here, we introduce spatial Genetic Diversity (sGD), a new spatially explicit tool to estimate genetic diversity based on grouping individuals into potentially overlapping genetic neighbourhoods that match the population structure, whether discrete or clinal. We compared the estimates and patterns of genetic diversity using patch or regional sampling and sGD on both simulated and empirical populations. When the population did not meet the assumptions of an island model, we found that patch and regional sampling generally overestimated local heterozygosity, inbreeding and allelic diversity. Moreover, sGD revealed fine-scale spatial heterogeneity in genetic diversity that was not evident with patch or regional sampling. These advantages should provide a more robust means to evaluate the potential for genetic factors to influence the viability of clinal populations and guide appropriate conservation plans. © 2011 Blackwell Publishing Ltd.

Characterization of casein gene complex and genetic diversity analysis in Indian goats.

PubMed

Rout, P K; Kumar, A; Mandal, A; Laloe, D; Singh, S K; Roy, R

2010-04-01

Milk protein polymorphism plays an important role in genetic diversity analysis, phylogenetic studies, establishing geographical diversity, conservation decision, and improving breeding goals. Milk protein polymorphism in Indian goat breeds has not been well studied; therefore, an investigation was carried out to analyze the genetic structure of the casein gene and milk protein diversity at six milk protein loci in nine Indian goat breeds/genetic groups from varied agro-climatic zones. Milk protein genotyping was carried out in 1098 individual milk samples by SDS-PAGE at alphaS1-CN (CSN1S1), beta-CN (CSN2), alphaS2-CN (CSN1S2), kappa-CN (CSN3), beta-LG, and alpha-LA loci. Indian goats exhibited alphaS1-casein A allele in higher frequency in the majority of breeds except Ganjam and local goats. The alphaS1-casein A allele frequencies varied from 0.45 to 0.77. A total of 16 casein haplotypes were observed in seven breeds and breed specific haplotypes were observed with respect to geographic region. The average number of alleles was lowest in Ganjam (1.66 +/- 0.81) and highest in Sirohi goats (2.50 +/- 1.05). Expected heterozygosity at six different loci demonstrated genetic diversity and breed fragmentation. Neighbor-Joining tree was built basing on Nei's distance. There was about 16.95% variability due to differences between breeds, indicating a strong subdivision. Principal component analysis was carried out to highlight the relationship among breeds. The variability among goat breeds was contributed by alphaS2-CN, beta-LG and alphaS1-CN. The Indian goats exhibited alphaS1-CN (CSN1S1) A allele in higher frequency in all the breeds indicating the higher casein yield in their milk.

MHC variability supports dog domestication from a large number of wolves: high diversity in Asia.

PubMed

Niskanen, A K; Hagström, E; Lohi, H; Ruokonen, M; Esparza-Salas, R; Aspi, J; Savolainen, P

2013-01-01

The process of dog domestication is still somewhat unresolved. Earlier studies indicate that domestic dogs from all over the world have a common origin in Asia. So far, major histocompatibility complex (MHC) diversity has not been studied in detail in Asian dogs, although high levels of genetic diversity are expected at the domestication locality. We sequenced the second exon of the canine MHC gene DLA-DRB1 from 128 Asian dogs and compared our data with a previously published large data set of MHC alleles, mostly from European dogs. Our results show that Asian dogs have a higher MHC diversity than European dogs. We also estimated that there is only a small probability that new alleles have arisen by mutation since domestication. Based on the assumption that all of the currently known 102 DLA-DRB1 alleles come from the founding wolf population, we simulated the number of founding wolf individuals. Our simulations indicate an effective population size of at least 500 founding wolves, suggesting that the founding wolf population was large or that backcrossing has taken place.

MHC variability supports dog domestication from a large number of wolves: high diversity in Asia

PubMed Central

Niskanen, A K; Hagström, E; Lohi, H; Ruokonen, M; Esparza-Salas, R; Aspi, J; Savolainen, P

2013-01-01

The process of dog domestication is still somewhat unresolved. Earlier studies indicate that domestic dogs from all over the world have a common origin in Asia. So far, major histocompatibility complex (MHC) diversity has not been studied in detail in Asian dogs, although high levels of genetic diversity are expected at the domestication locality. We sequenced the second exon of the canine MHC gene DLA–DRB1 from 128 Asian dogs and compared our data with a previously published large data set of MHC alleles, mostly from European dogs. Our results show that Asian dogs have a higher MHC diversity than European dogs. We also estimated that there is only a small probability that new alleles have arisen by mutation since domestication. Based on the assumption that all of the currently known 102 DLA–DRB1 alleles come from the founding wolf population, we simulated the number of founding wolf individuals. Our simulations indicate an effective population size of at least 500 founding wolves, suggesting that the founding wolf population was large or that backcrossing has taken place. PMID:23073392

Study of Genetic Diversity among Simmental Cross Cattle in West Sumatra Based on Microsatellite Markers

PubMed Central

Agung, Paskah Partogi; Saputra, Ferdy; Septian, Wike Andre; Lusiana; Zein, Moch. Syamsul Arifin; Sulandari, Sri; Anwar, Saiful; Wulandari, Ari Sulistyo; Said, Syahruddin; Tappa, Baharuddin

2016-01-01

A study was conducted to assess the genetic diversity among Simmental Cross cattle in West Sumatra using microsatellite DNA markers. A total of 176 individual cattle blood samples was used for obtaining DNA samples. Twelve primers of microsatellite loci as recommended by FAO were used to identify the genetic diversity of the Simmental Cross cattle population. Multiplex DNA fragment analysis method was used for allele identification. All the microsatellite loci in this study were highly polymorphic and all of the identified alleles were able to classify the cattle population into several groups based on their genetic distance. The heterozygosity values of microsatellite loci in this study ranged from 0.556 to 0.782. The polymorphism information content (PIC) value of the 12 observed loci is high (PIC>0.5). The highest PIC value in the Simmental cattle population was 0.893 (locus TGLA53), while the lowest value was 0.529 (locus BM1818). Based on the genetic distance value, the subpopulation of the Simmental Cross-Agam and the Simmental Cross-Limapuluh Kota was exceptionally close to the Simmental Purebred thus indicating that a grading-up process has taken place with the Simmental Purebred. In view of the advantages possessed by the Simmental Cross cattle and the evaluation of the genetic diversity results, a number of subpopulations in this study can be considered as the initial (base) population for the Simmental Cross cattle breeding programs in West Sumatra, Indonesia. PMID:26732442

Efficiency of RAPD versus SSR markers for determining genetic diversity among popcorn lines.

PubMed

Leal, A A; Mangolin, C A; do Amaral, A T; Gonçalves, L S A; Scapim, C A; Mott, A S; Eloi, I B O; Cordovés, V; da Silva, M F P

2010-01-05

Using only one type of marker to quantify genetic diversity generates results that have been questioned in terms of reliability, when compared to the combined use of different markers. To compare the efficiency of the use of single versus multiple markers, we quantified genetic diversity among 10 S(7) inbred popcorn lines using both RAPD and SSR markers, and we evaluated how well these two types of markers discriminated the popcorn genotypes. These popcorn genotypes: "Yellow Pearl Popcorn" (P1-1 and P1-5), "Zélia" (P1-2 and P1-4), "Curagua" (P1-3), "IAC 112" (P9-1 and P9-2), "Avati Pichinga" (P9-3 and P9-5), and "Pisankalla" (P9-4) have different soil and climate adaptations. Using RAPD marker analysis, each primer yielded bands of variable intensities that were easily detected, as well as non-specific bands, which were discarded from the analysis. The nine primers used yielded 126 bands, of which 104 were classified as polymorphic, giving an average of 11.6 polymorphisms per primer. Using SSR procedures, the number of alleles per locus ranged from two to five, giving a total of 47 alleles for the 14 SSR loci. When comparing the groups formed using SSR and RAPD markers, there were similarities in the combinations of genotypes from the same genealogy. Correlation between genetic distances obtained through RAPD and SSR markers was relatively high (0.5453), indicating that both techniques are efficient for evaluating genetic diversity in the genotypes of popcorn that we evaluated, though RAPDs yielded more polymorphisms.

Characteristics of allelic gene expression in human brain cells from single-cell RNA-seq data analysis.

PubMed

Zhao, Dejian; Lin, Mingyan; Pedrosa, Erika; Lachman, Herbert M; Zheng, Deyou

2017-11-10

Monoallelic expression of autosomal genes has been implicated in human psychiatric disorders. However, there is a paucity of allelic expression studies in human brain cells at the single cell and genome wide levels. In this report, we reanalyzed a previously published single-cell RNA-seq dataset from several postmortem human brains and observed pervasive monoallelic expression in individual cells, largely in a random manner. Examining single nucleotide variants with a predicted functional disruption, we found that the "damaged" alleles were overall expressed in fewer brain cells than their counterparts, and at a lower level in cells where their expression was detected. We also identified many brain cell type-specific monoallelically expressed genes. Interestingly, many of these cell type-specific monoallelically expressed genes were enriched for functions important for those brain cell types. In addition, function analysis showed that genes displaying monoallelic expression and correlated expression across neuronal cells from different individual brains were implicated in the regulation of synaptic function. Our findings suggest that monoallelic gene expression is prevalent in human brain cells, which may play a role in generating cellular identity and neuronal diversity and thus increasing the complexity and diversity of brain cell functions.

Comparisons of genetic diversity in captive versus wild populations of the federally endangered Quino checkerspot butterfly (Euphydryas editha quino Behr; Lepidoptera: Nymphalidae)

USGS Publications Warehouse

Miller, Mark P.; Pratt, Gordon F.; Mullins, Thomas D.; Haig, Susan M.

2014-01-01

Captive populations can play a significant role in threatened and endangered species management. An important consideration when developing and managing captive populations, however, is the maintenance of genetic diversity to ensure that adequate variation exists to avoid the negative consequences of inbreeding. In this investigation, we compared genetic diversity patterns within captive and wild populations of the federally endangered Quino checkerspot butterfly (Euphydryas editha quino Behr [Lepidoptera: Nymphalidae]), a taxon with a restricted distribution to chaparral and sage shrublands within Riverside and San Diego counties, California. Our analyses revealed that medium to high-frequency alleles from the wild populations were also present in the captive populations. While there was no significant difference in genetic diversity as quantified by expected heterozygosity, the captive populations showed tendencies toward significantly lower allelic richness than their wild counterparts. Given that alleles from the wild populations were occasionally not detected in captive populations, periodic incorporation of new wild specimens into the captive population would help ensure that allelic diversity is maintained to the extent possible. If performed in advance, genetic surveys of wild populations may provide the clearest insights regarding the number of individuals needed in captivity to adequately reflect wild populations.

A Diverse Range of Novel RNA Viruses in Geographically Distinct Honey Bee Populations

PubMed Central

Shi, Mang; Buchmann, Gabriele; Blacquière, Tjeerd; Beekman, Madeleine; Ashe, Alyson

2017-01-01

overwhelmed with high levels of picornaviruses. To examine the underlying viral diversity in honey bees, we employed viral metatranscriptomics analyses on three geographically diverse Varroa-resistant populations from Europe, Africa, and the Pacific. We describe seven novel viruses from a range of diverse viral families, including two viruses that are present in all three locations. In honey bees, small RNA sequences indicate that these viruses are processed by Dicer and the RNA interference pathway, whereas Varroa mites produce strikingly novel small RNA patterns. This work increases the number and diversity of known honey bee viruses and will ultimately contribute to improved disease management in our most important agricultural pollinator. PMID:28515299

A Diverse Range of Novel RNA Viruses in Geographically Distinct Honey Bee Populations.

PubMed

Remnant, Emily J; Shi, Mang; Buchmann, Gabriele; Blacquière, Tjeerd; Holmes, Edward C; Beekman, Madeleine; Ashe, Alyson

2017-08-15

with high levels of picornaviruses. To examine the underlying viral diversity in honey bees, we employed viral metatranscriptomics analyses on three geographically diverse Varroa- resistant populations from Europe, Africa, and the Pacific. We describe seven novel viruses from a range of diverse viral families, including two viruses that are present in all three locations. In honey bees, small RNA sequences indicate that these viruses are processed by Dicer and the RNA interference pathway, whereas Varroa mites produce strikingly novel small RNA patterns. This work increases the number and diversity of known honey bee viruses and will ultimately contribute to improved disease management in our most important agricultural pollinator. Copyright © 2017 Remnant et al.

Evaluating genetic diversity and constructing core collections of Chinese Lentinula edodes cultivars using ISSR and SRAP markers.

PubMed

Liu, Jun; Wang, Zhuo-Ren; Li, Chuang; Bian, Yin-Bing; Xiao, Yang

2015-06-01

Genetic diversity among 89 Chinese Lentinula edodes cultivars was analyzed by inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers. A 123 out of 126 ISSR loci (97.62%) and 108 out of 129 SRAP loci (83.73%) were polymorphic between two or more strains. A dendrogram constructed by cluster analysis based on the ISSR and SRAP markers separated the L. edodes strains into two major groups, of which group B was further divided into five subgroups. Clustering results also showed a positive correlation with the main agronomic traits of the strains, and that strains with similar traits clustered together into the same groups or subgroups in most cases. The average coefficient of pairwise genetic similarity was 0.820 (range: 0.576-0.988). Compared to the wild strains, Chinese L. edodes cultivars indicated a lower level of genetic diversity. Two preliminary core collections of L. edodes, Core1 and Core2, were established based on the ISSR and SRAP data, respectively. Core1 was constructed by the advanced M (maximization) strategy using the PowerCore version 1.0 software and contained 21 strains, whereas Core2 was created by the allele preferred sampling strategy using the cluster method and contained 18 strains. Both core collections were highly representative of the genetic diversity of the original germplasm, as confirmed by the values of Na (observed number of alleles), Ne (effective number of alleles), H (Nei's gene diversity) and I (Shannon's information index), as well as results of principal coordinate analysis. The loci retention ratio of Core1 (99.61%) was higher than that of Core2 (97.65%). Moreover, Core1 contained strains with more types of agronomic traits than those in Core2. This study builds the basis for further effective protection, management and use of L. edodes germplasm resource. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Variability of Sesquiterpenes Emitted from Two Zea mays Cultivars Is Controlled by Allelic Variation of Two Terpene Synthase Genes Encoding Stereoselective Multiple Product Enzymes

PubMed Central

Köllner, Tobias G.; Schnee, Christiane; Gershenzon, Jonathan; Degenhardt, Jörg

2004-01-01

The mature leaves and husks of Zea mays release a complex blend of terpene volatiles after anthesis consisting predominantly of bisabolane-, sesquithujane-, and bergamotane-type sesquiterpenes. The varieties B73 and Delprim release the same volatile constituents but in significantly different proportions. To study the molecular genetic and biochemical mechanisms controlling terpene diversity and distribution in these varieties, we isolated the closely related terpene synthase genes terpene synthase4 (tps4) and tps5 from both varieties. The encoded enzymes, TPS4 and TPS5, each formed the same complex mixture of sesquiterpenes from the precursor farnesyl diphosphate but with different proportions of products. These mixtures correspond to the sesquiterpene blends observed in the varieties B73 and Delprim, respectively. The differences in the stereoselectivity of TPS4 and TPS5 are determined by four amino acid substitutions with the most important being a Gly instead of an Ala residue at position 409 at the catalytic site of the enzyme. Although both varieties contain tps4 and tps5 alleles, their differences in terpene composition result from the fact that B73 has only a single functional allele of tps4 and no functional alleles of tps5, whereas Delprim has only a functional allele of tps5 and no functional alleles of tps4. Lack of functionality was shown to be attributable to frame-shift mutations or amino acid substitutions that greatly reduce the activity of their encoded proteins. Therefore, the diversity of sesquiterpenes in these two maize cultivars is strongly influenced by single nucleotide changes in the alleles of two terpene synthase genes. PMID:15075399

The variability of sesquiterpenes emitted from two Zea mays cultivars is controlled by allelic variation of two terpene synthase genes encoding stereoselective multiple product enzymes.

PubMed

Köllner, Tobias G; Schnee, Christiane; Gershenzon, Jonathan; Degenhardt, Jörg

2004-05-01

The mature leaves and husks of Zea mays release a complex blend of terpene volatiles after anthesis consisting predominantly of bisabolane-, sesquithujane-, and bergamotane-type sesquiterpenes. The varieties B73 and Delprim release the same volatile constituents but in significantly different proportions. To study the molecular genetic and biochemical mechanisms controlling terpene diversity and distribution in these varieties, we isolated the closely related terpene synthase genes terpene synthase4 (tps4) and tps5 from both varieties. The encoded enzymes, TPS4 and TPS5, each formed the same complex mixture of sesquiterpenes from the precursor farnesyl diphosphate but with different proportions of products. These mixtures correspond to the sesquiterpene blends observed in the varieties B73 and Delprim, respectively. The differences in the stereoselectivity of TPS4 and TPS5 are determined by four amino acid substitutions with the most important being a Gly instead of an Ala residue at position 409 at the catalytic site of the enzyme. Although both varieties contain tps4 and tps5 alleles, their differences in terpene composition result from the fact that B73 has only a single functional allele of tps4 and no functional alleles of tps5, whereas Delprim has only a functional allele of tps5 and no functional alleles of tps4. Lack of functionality was shown to be attributable to frame-shift mutations or amino acid substitutions that greatly reduce the activity of their encoded proteins. Therefore, the diversity of sesquiterpenes in these two maize cultivars is strongly influenced by single nucleotide changes in the alleles of two terpene synthase genes.

A powerful and flexible statistical framework for testing hypotheses of allele-specific gene expression from RNA-seq data

PubMed Central

Skelly, Daniel A.; Johansson, Marnie; Madeoy, Jennifer; Wakefield, Jon; Akey, Joshua M.

2011-01-01

Variation in gene expression is thought to make a significant contribution to phenotypic diversity among individuals within populations. Although high-throughput cDNA sequencing offers a unique opportunity to delineate the genome-wide architecture of regulatory variation, new statistical methods need to be developed to capitalize on the wealth of information contained in RNA-seq data sets. To this end, we developed a powerful and flexible hierarchical Bayesian model that combines information across loci to allow both global and locus-specific inferences about allele-specific expression (ASE). We applied our methodology to a large RNA-seq data set obtained in a diploid hybrid of two diverse Saccharomyces cerevisiae strains, as well as to RNA-seq data from an individual human genome. Our statistical framework accurately quantifies levels of ASE with specified false-discovery rates, achieving high reproducibility between independent sequencing platforms. We pinpoint loci that show unusual and biologically interesting patterns of ASE, including allele-specific alternative splicing and transcription termination sites. Our methodology provides a rigorous, quantitative, and high-resolution tool for profiling ASE across whole genomes. PMID:21873452

Human minisatellite alleles detectable only after PCR amplification.

PubMed

Armour, J A; Crosier, M; Jeffreys, A J

1992-01-01

We present evidence that a proportion of alleles at two human minisatellite loci is undetected by standard Southern blot hybridization. In each case the missing allele(s) can be identified after PCR amplification and correspond to tandem arrays too short to detect by hybridization. At one locus, there is only one undetected allele (population frequency 0.3), which contains just three repeat units. At the second locus, there are at least five undetected alleles (total population frequency 0.9) containing 60-120 repeats; they are not detected because these tandem repeats give very poor signals when used as a probe in standard Southern blot hybridization, and also cross-hybridize with other sequences in the genome. Under these circumstances only signals from the longest tandemly repeated alleles are detectable above the nonspecific background. The structures of these loci have been compared in human and primate DNA, and at one locus the short human allele containing three repeat units is shown to be an intermediate state in the expansion of a monomeric precursor allele in primates to high copy number in the longer human arrays. We discuss the implications of such loci for studies of human populations, minisatellite isolation by cloning, and the evolution of highly variable tandem arrays.

High-Level Genetic Diversity and Complex Population Structure of Siberian Apricot (Prunus sibirica L.) in China as Revealed by Nuclear SSR Markers

PubMed Central

Wang, Zhe; Kang, Ming; Liu, Huabo; Gao, Jiao; Zhang, Zhengdong; Li, Yingyue; Wu, Rongling; Pang, Xiaoming

2014-01-01

Siberian apricot (Prunus sibirica L.), an ecologically and economically important tree species with a high degree of tolerance to a variety of extreme environmental conditions, is widely distributed across the mountains of northeastern and northern China, eastern and southeastern regions of Mongolia, Eastern Siberia, and the Maritime Territory of Russia. However, few studies have examined the genetic diversity and population structure of this species. Using 31 nuclear microsatellites, we investigated the level of genetic diversity and population structure of Siberian apricot sampled from 22 populations across China. The number of alleles per locus ranged from 5 to 33, with an average of 19.323 alleles. The observed heterozygosity and expected heterozygosity ranged from 0.037 to 0.874 and 0.040 to 0.924 with average values of 0.639 and 0.774, respectively. A STRUCTURE-based analysis clustered all of the populations into four genetic clusters. Significant genetic differentiation was observed between all population pairs. A hierarchical analysis of molecular variance attributed about 94% of the variation to within populations. No significant difference was detected between the wild and semi-wild groups, indicating that recent cultivation practices have had little impact on the genetic diversity of Siberian apricot. The Mantel test showed that the genetic distance among the populations was not significantly correlated with geographic distance (r = 0.4651, p = 0.9940). Our study represents the most comprehensive investigation of the genetic diversity and population structure of Siberian apricot in China to date, and it provides valuable information for the collection of genetic resources for the breeding of Siberian apricot and related species. PMID:24516551

Considerable MHC Diversity Suggests That the Functional Extinction of Baiji Is Not Related to Population Genetic Collapse

PubMed Central

Xu, Shixia; Ju, Jianfeng; Zhou, Xuming; Wang, Lian; Zhou, Kaiya; Yang, Guang

2012-01-01

To further extend our understanding of the mechanism causing the current nearly extinct status of the baiji (Lipotes vexillifer), one of the most critically endangered species in the world, genetic diversity at the major histocompatibility complex (MHC) class II DRB locus was investigated in the baiji. Nine highly divergent DRB alleles were identified in 17 samples, with an average of 28.4 (13.2%) nucleotide difference and 16.7 (23.5%) amino acid difference between alleles. The unexpectedly high levels of DRB allelic diversity in the baiji may partly be attributable to its evolutionary adaptations to the freshwater environment which is regarded to have a higher parasite diversity compared to the marine environment. In addition, balancing selection was found to be the main mechanisms in generating sequence diversity at baiji DRB gene. Considerable sequence variation at the adaptive MHC genes despite of significant loss of neutral genetic variation in baiji genome might suggest that intense selection has overpowered random genetic drift as the main evolutionary forces, which further suggested that the critically endangered or nearly extinct status of the baiji is not an outcome of genetic collapse. PMID:22272349

Development and characterization of novel EST-SSR markers and their application for genetic diversity analysis of Jerusalem artichoke (Helianthus tuberosus L.).

PubMed

Mornkham, T; Wangsomnuk, P P; Mo, X C; Francisco, F O; Gao, L Z; Kurzweil, H

2016-10-24

Jerusalem artichoke (Helianthus tuberosus L.) is a perennial tuberous plant and a traditional inulin-rich crop in Thailand. It has become the most important source of inulin and has great potential for use in chemical and food industries. In this study, expressed sequence tag (EST)-based simple sequence repeat (SSR) markers were developed from 40,362 Jerusalem artichoke ESTs retrieved from the NCBI database. Among 23,691 non-redundant identified ESTs, 1949 SSR motifs harboring 2 to 6 nucleotides with varied repeat motifs were discovered from 1676 assembled sequences. Seventy-nine primer pairs were generated from EST sequences harboring SSR motifs. Our results show that 43 primers are polymorphic for the six studied populations, while the remaining 36 were either monomorphic or failed to amplify. These 43 SSR loci exhibited a high level of genetic diversity among populations, with allele numbers varying from 2 to 7, with an average of 3.95 alleles per loci. Heterozygosity ranged from 0.096 to 0.774, with an average of 0.536; polymorphic index content ranged from 0.096 to 0.854, with an average of 0.568. Principal component analysis and neighbor-joining analysis revealed that the six populations could be divided into six clusters. Our results indicate that these newly characterized EST-SSR markers may be useful in the exploration of genetic diversity and range expansion of the Jerusalem artichoke, and in cross-species application for the genus Helianthus.

Huntingtin Haplotypes Provide Prioritized Target Panels for Allele-specific Silencing in Huntington Disease Patients of European Ancestry

PubMed Central

Kay, Chris; Collins, Jennifer A; Skotte, Niels H; Southwell, Amber L; Warby, Simon C; Caron, Nicholas S; Doty, Crystal N; Nguyen, Betty; Griguoli, Annamaria; Ross, Colin J; Squitieri, Ferdinando; Hayden, Michael R

2015-01-01

Huntington disease (HD) is a dominant neurodegenerative disorder caused by a CAG repeat expansion in the Huntingtin gene (HTT). Heterozygous polymorphisms in cis with the mutation allow for allele-specific suppression of the pathogenic HTT transcript as a therapeutic strategy. To prioritize target selection, precise heterozygosity estimates are needed across diverse HD patient populations. Here we present the first comprehensive investigation of all common target alleles across the HTT gene, using 738 reference haplotypes from the 1000 Genomes Project and 2364 haplotypes from HD patients and relatives in Canada, Sweden, France, and Italy. The most common HD haplotypes (A1, A2, and A3a) define mutually exclusive sets of polymorphisms for allele-specific therapy in the greatest number of patients. Across all four populations, a maximum of 80% are treatable using these three target haplotypes. We identify a novel deletion found exclusively on the A1 haplotype, enabling potent and selective silencing of mutant HTT in approximately 40% of the patients. Antisense oligonucleotides complementary to the deletion reduce mutant A1 HTT mRNA by 78% in patient cells while sparing wild-type HTT expression. By suppressing specific haplotypes on which expanded CAG occurs, we demonstrate a rational approach to the development of allele-specific therapy for a monogenic disorder. PMID:26201449

Mapping the mouse Allelome reveals tissue-specific regulation of allelic expression

PubMed Central

Andergassen, Daniel; Dotter, Christoph P; Wenzel, Daniel; Sigl, Verena; Bammer, Philipp C; Muckenhuber, Markus; Mayer, Daniela; Kulinski, Tomasz M; Theussl, Hans-Christian; Penninger, Josef M; Bock, Christoph; Barlow, Denise P; Pauler, Florian M; Hudson, Quanah J

2017-01-01

To determine the dynamics of allelic-specific expression during mouse development, we analyzed RNA-seq data from 23 F1 tissues from different developmental stages, including 19 female tissues allowing X chromosome inactivation (XCI) escapers to also be detected. We demonstrate that allelic expression arising from genetic or epigenetic differences is highly tissue-specific. We find that tissue-specific strain-biased gene expression may be regulated by tissue-specific enhancers or by post-transcriptional differences in stability between the alleles. We also find that escape from X-inactivation is tissue-specific, with leg muscle showing an unexpectedly high rate of XCI escapers. By surveying a range of tissues during development, and performing extensive validation, we are able to provide a high confidence list of mouse imprinted genes including 18 novel genes. This shows that cluster size varies dynamically during development and can be substantially larger than previously thought, with the Igf2r cluster extending over 10 Mb in placenta. DOI: http://dx.doi.org/10.7554/eLife.25125.001 PMID:28806168

Range-azimuth decouple beamforming for frequency diverse array with Costas-sequence modulated frequency offsets

NASA Astrophysics Data System (ADS)

Wang, Zhe; Wang, Wen-Qin; Shao, Huaizong

2016-12-01

Different from the phased-array using the same carrier frequency for each transmit element, the frequency diverse array (FDA) uses a small frequency offset across the array elements to produce range-angle-dependent transmit beampattern. FDA radar provides new application capabilities and potentials due to its range-dependent transmit array beampattern, but the FDA using linearly increasing frequency offsets will produce a range and angle coupled transmit beampattern. In order to decouple the range-azimuth beampattern for FDA radar, this paper proposes a uniform linear array (ULA) FDA using Costas-sequence modulated frequency offsets to produce random-like energy distribution in the transmit beampattern and thumbtack transmit-receive beampattern. In doing so, the range and angle of targets can be unambiguously estimated through matched filtering and subspace decomposition algorithms in the receiver signal processor. Moreover, random-like energy distributed beampattern can also be utilized for low probability of intercept (LPI) radar applications. Numerical results show that the proposed scheme outperforms the standard FDA in focusing the transmit energy, especially in the range dimension.

Extensive genetic diversity present within North American switchgrass germplasm

USDA-ARS?s Scientific Manuscript database

Switchgrass (Panicum virgatum L.) is a perennial, native North American grass currently grown for ecological restoration and forage purposes that has potential as a biofuel feedstock crop. Understanding the genetic diversity of switchgrass can provide insight into allelic variants important in devel...

A rapid, highly accurate method for quantifying CALR mutant allele burden in persons with myeloproliferative neoplasms.

PubMed

Yao, Qiu-Mei; Zhou, Jiao; Gale, Robert Peter; Li, Jin-Lan; Li, Ling-Di; Li, Ning; Chen, Shan-Shan; Ruan, Guo-Rui

2015-10-01

Calreticulin (CALR) mutations were recently identified in a substantial proportion of persons with essential thrombocythemia (ET) and with primary myelofibrosis (PMF) without JAK2(V617F). Consequently rapid, sensitive, and specific methods to detect and quantify these mutations are needed. We studied samples from 1088 persons with myeloproliferative neoplasms (MPNs) including 421 JAK2(V617F) negative subjects with ET, PMF, polycythemia vera (PV), chronic myeloid leukemia (CML) and hyper-eosinophilic syndrome (HES). Detection of CALR exon 9 mutations was done by PCR amplification followed by fragment length analysis and direct sequencing. Dilution assays were used to determine CALR mutant allele burden. We detected CALR mutations in blood and bone marrow samples from 152 subjects with ET and with PMF but not in samples from normal or persons with PV, CML, or HES. CALR mutant peaks were distinct from wild-type peaks and dilution experiments indicated a sensitivity level of 0.5-5% for a CALR mutant allele in a wild-type background. Diverse types of mutations were detected including deletions, insertions, and complex indels. All mutations were confirmed by direct sequencing. We also used dilution experiments to quantify mutant allele burden. We were able to reproducibly detect mutant allele levels as low 5% (0.5-5%) in a wild-type background. PCR amplification followed by fragment length analysis is a rapid, sensitive, and specific method for screening persons with MPNs for CALR mutations, especially those with ET and PMF and for estimating mutant allele burden.

Phenotypic and genotypic expression of self-incompatibility haplotypes in Arabidopsis lyrata suggests unique origin of alleles in different dominance classes.

PubMed

Prigoda, Nadia L; Nassuth, Annette; Mable, Barbara K

2005-07-01

conversion might have contributed to allelic diversity is discussed.

Genetic diversity trend in Indian rice varieties: an analysis using SSR markers.

PubMed

Singh, Nivedita; Choudhury, Debjani Roy; Tiwari, Gunjan; Singh, Amit Kumar; Kumar, Sundeep; Srinivasan, Kalyani; Tyagi, R K; Sharma, A D; Singh, N K; Singh, Rakesh

2016-09-05

The knowledge of the extent and pattern of diversity in the crop species is a prerequisite for any crop improvement as it helps breeders in deciding suitable breeding strategies for their future improvement. Rice is the main staple crop in India with the large number of varieties released every year. Studies based on the small set of rice genotypes have reported a loss in genetic diversity especially after green revolution. However, a detailed study of the trend of diversity in Indian rice varieties is lacking. SSR markers have proven to be a marker of choice for studying the genetic diversity. Therefore, the present study was undertaken with the aim to characterize and assess trends of genetic diversity in a large set of Indian rice varieties (released between 1940-2013), conserved in the National Gene Bank of India using SSR markers. A set of 729 Indian rice varieties were genotyped using 36 HvSSR markers to assess the genetic diversity and genetic relationship. A total of 112 alleles was amplified with an average of 3.11 alleles per locus with mean Polymorphic Information Content (PIC) value of 0.29. Cluster analysis grouped these varieties into two clusters whereas the model based population structure divided them into three populations. AMOVA study based on hierarchical cluster and model based approach showed 3 % and 11 % variation between the populations, respectively. Decadal analysis for gene diversity and PIC showed increasing trend from 1940 to 2005, thereafter values for both the parameters showed decreasing trend between years 2006-2013. In contrast to this, allele number demonstrated increasing trend in these varieties released and notified between1940 to 1985, it remained nearly constant during 1986 to 2005 and again showed an increasing trend. Our results demonstrated that the Indian rice varieties harbors huge amount of genetic diversity. However, the trait based improvement program in the last decades forced breeders to rely on few parents, which

Alleles versus mutations: Understanding the evolution of genetic architecture requires a molecular perspective on allelic origins.

PubMed

Remington, David L

2015-12-01

Perspectives on the role of large-effect quantitative trait loci (QTL) in the evolution of complex traits have shifted back and forth over the past few decades. Different sets of studies have produced contradictory insights on the evolution of genetic architecture. I argue that much of the confusion results from a failure to distinguish mutational and allelic effects, a limitation of using the Fisherian model of adaptive evolution as the lens through which the evolution of adaptive variation is examined. A molecular-based perspective reveals that allelic differences can involve the cumulative effects of many mutations plus intragenic recombination, a model that is supported by extensive empirical evidence. I discuss how different selection regimes could produce very different architectures of allelic effects under a molecular-based model, which may explain conflicting insights on genetic architecture from studies of variation within populations versus between divergently selected populations. I address shortcomings of genome-wide association study (GWAS) practices in light of more suitable models of allelic evolution, and suggest alternate GWAS strategies to generate more valid inferences about genetic architecture. Finally, I discuss how adopting more suitable models of allelic evolution could help redirect research on complex trait evolution toward addressing more meaningful questions in evolutionary biology. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Influence of ethnic traditional cultures on genetic diversity of rice landraces under on-farm conservation in southwest China.

PubMed

Wang, Yanjie; Wang, Yanli; Sun, Xiaodong; Caiji, Zhuoma; Yang, Jingbiao; Cui, Di; Cao, Guilan; Ma, Xiaoding; Han, Bing; Xue, Dayuan; Han, Longzhi

2016-10-27

Crop genetic resources are important components of biodiversity. However, with the large-scale promotion of mono-cropping, genetic diversity has largely been lost. Ex-situ conservation approaches were widely used to protect traditional crop varieties worldwide. However, this method fails to maintain the dynamic evolutionary processes of crop genetic resources in their original habitats, leading to genetic diversity reduction and even loss of the capacity of resistance to new diseases and pests. Therefore, on-farm conservation has been considered a crucial complement to ex-situ conservation. This study aimed at clarifying the genetic diversity differences between ex-situ conservation and on-farm conservation and to exploring the influence of traditional cultures on genetic diversity of rice landraces under on-farm conservation. The conservation status of rice landrace varieties, including Indica and Japonica, non-glutinous rice (Oryza sativa) and glutinous rice (Oryza sativa var. glutinosa Matsum), was obtained through ethno-biology investigation method in 12 villages of ethnic groups from Guizhou, Yunnan and Guangxi provinces of China. The genetic diversity between 24 pairs of the same rice landraces from different times were compared using simple sequence repeat (SSR) molecular markers technology. The landrace paris studied were collected in 1980 and maintained ex-situ, while 2014 samples were collected on-farm in southwest of China. The results showed that many varieties of rice landraces have been preserved on-farm by local farmers for hundreds or thousands of years. The number of alleles (Na), effective number of alleles (Ne), Nei genetic diversity index (He) and Shannon information index (I) of rice landraces were significantly higher by 12.3-30.4 % under on-farm conservation than under ex-situ conservation. Compared with the ex-situ conservation approach, rice landraces under on-farm conservation programs had more alleles and higher genetic diversity. In

Sex-chromosome differentiation parallels postglacial range expansion in European tree frogs (Hyla arborea).

PubMed

Dufresnes, Christophe; Bertholet, Youna; Wassef, Jérôme; Ghali, Karim; Savary, Romain; Pasteur, Baptiste; Brelsford, Alan; Rozenblut-Kościsty, Beata; Ogielska, Maria; Stöck, Matthias; Perrin, Nicolas

2014-12-01

Occasional XY recombination is a proposed explanation for the sex-chromosome homomorphy in European tree frogs. Numerous laboratory crosses, however, failed to detect any event of male recombination, and a detailed survey of NW-European Hyla arborea populations identified male-specific alleles at sex-linked loci, pointing to the absence of XY recombination in their recent history. Here, we address this paradox in a phylogeographic framework by genotyping sex-linked microsatellite markers in populations and sibships from the entire species range. Contrasting with postglacial populations of NW Europe, which display complete absence of XY recombination and strong sex-chromosome differentiation, refugial populations of the southern Balkans and Adriatic coast show limited XY recombination and large overlaps in allele frequencies. Geographically and historically intermediate populations of the Pannonian Basin show intermediate patterns of XY differentiation. Even in populations where X and Y occasionally recombine, the genetic diversity of Y haplotypes is reduced below the levels expected from the fourfold drop in copy numbers. This study is the first in which X and Y haplotypes could be phased over the distribution range in a species with homomorphic sex chromosomes; it shows that XY-recombination patterns may differ strikingly between conspecific populations, and that recombination arrest may evolve rapidly (<5000 generations). © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

A and MdMYB1 allele-specific markers controlling apple (Malus x domestica Borkh.) skin color and suitability for marker-assisted selection.

PubMed

Zhang, X J; Wang, L X; Chen, X X; Liu, Y L; Meng, R; Wang, Y J; Zhao, Z Y

2014-10-31

Pre-selection for fruit skin color at the seedling stage would be highly advantageous, with marker-assisted selection offering a potential method for apple pre-selection. A and MdMYB1 alleles are allele-specific DNA markers that are potentially associated with apple skin color, and co-segregate with the Rf and Rni loci, respectively. Here, we assessed the potential application of these 2 alleles for marker-assisted breeding across 30 diverse cultivars and 2 apple seedling progenies. The red skin color phenotype was usually associated with the MdMYB1-1 allele and A(1) allele, respectively, while the 2 molecular markers provided approximately 91% predictability in the 'Fuji' x 'Cripps Pink' and 'Fuji' x 'Gala' progenies. The results obtained from the 30 cultivars and 2 progenies were consistent for the 2 molecular markers. Hence, the results supported that Rf and Rni could be located in a gene cluster, or even correspond to alleles of the same gene. Our results are consistent with the hypothesis that red/yellow dimorphism is controlled by a monogenic system, with the presence of the red anthocyanin pigmentation being dominant. In addition, our results supported that the practical utilization of the 2 function markers to efficiently and accurately select red-skinned apple cultivars in apple scion breeding programs.

Somatic Mutation Allelic Ratio Test Using ddPCR (SMART-ddPCR): An Accurate Method for Assessment of Preferential Allelic Imbalance in Tumor DNA.

PubMed

de Smith, Adam J; Walsh, Kyle M; Hansen, Helen M; Endicott, Alyson A; Wiencke, John K; Metayer, Catherine; Wiemels, Joseph L

2015-01-01

The extent to which heritable genetic variants can affect tumor development has yet to be fully elucidated. Tumor selection of single nucleotide polymorphism (SNP) risk alleles, a phenomenon called preferential allelic imbalance (PAI), has been demonstrated in some cancer types. We developed a novel application of digital PCR termed Somatic Mutation Allelic Ratio Test using Droplet Digital PCR (SMART-ddPCR) for accurate assessment of tumor PAI, and have applied this method to test the hypothesis that heritable SNPs associated with childhood acute lymphoblastic leukemia (ALL) may demonstrate tumor PAI. These SNPs are located at CDKN2A (rs3731217) and IKZF1 (rs4132601), genes frequently lost in ALL, and at CEBPE (rs2239633), ARID5B (rs7089424), PIP4K2A (rs10764338), and GATA3 (rs3824662), genes located on chromosomes gained in high-hyperdiploid ALL. We established thresholds of AI using constitutional DNA from SNP heterozygotes, and subsequently measured allelic copy number in tumor DNA from 19-142 heterozygote samples per SNP locus. We did not find significant tumor PAI at these loci, though CDKN2A and IKZF1 SNPs showed a trend towards preferential selection of the risk allele (p = 0.17 and p = 0.23, respectively). Using a genomic copy number control ddPCR assay, we investigated somatic copy number alterations (SCNA) underlying AI at CDKN2A and IKZF1, revealing a complex range of alterations including homozygous and hemizygous deletions and copy-neutral loss of heterozygosity, with varying degrees of clonality. Copy number estimates from ddPCR showed high agreement with those from multiplex ligation-dependent probe amplification (MLPA) assays. We demonstrate that SMART-ddPCR is a highly accurate method for investigation of tumor PAI and for assessment of the somatic alterations underlying AI. Furthermore, analysis of publicly available data from The Cancer Genome Atlas identified 16 recurrent SCNA loci that contain heritable cancer risk SNPs associated with a

[Analysis of diversity of Russian and Ukrainian bread wheat (Triticum aestivum L.) cultivars for high-molecular-weight glutenin subunits].

PubMed

Dobrotvorskaia, T V; Martynov, S P

2011-07-01

The allelic diversity of high-moleculat-weght glutenin subunits (H WIGS) in Russian and Ukrainian bread wheat cultivars was analyzed. The diversity of spring wheat cultivars for alleles of the Glu-1 loci is characterized by medium values of the polymorphism index (polymorphism information content, PlC), and in winter wheats it varies from high at the Glu-A1 locus to low at the Glu-D1 locus. The spring and winter cultivars differ significantly in the frequencies of alleles of the glutenin loci. The combination of the Glu-A1b, Glu-B1c, and Glu-D1a alleles prevails among the spring cultivars, and the combination of the Glu-A1a, Glu-B1c, and Glu-D1d alleles prevails among the winter cultivars. The distribution of the Glu-1 alleles significantly depends on the moisture and heat supply in the region of origin of the cultivars. Drought resistance is associated with the Glu-D1a allele in the spring wheat and with the Glu-B1b allele in the winter wheat. The sources of the Glu-1 alleles were identified in the spring and wheat cultivars. The analysis of independence of the distribution of the spring and winter cultivars by the market classes and by the alleles of the HMWGS loci showed a highly significant association of the alleles of three Glu-1 loci with the market classes in foreign cultivars and independence or a weak association in the Russian and Ukrainian cultivars. This seems to be due to the absence of a statistically substantiated system of classification of the domestic cultivars on the basis of their quality.

Determination of Wolbachia Diversity in Butterflies from Western Ghats, India, by a Multigene Approach

PubMed Central

Salunke, Bipinchandra K.; Salunkhe, Rahul C.; Dhotre, Dhiraj P.; Walujkar, Sandeep A.; Khandagale, Avinash B.; Chaudhari, Rahul; Chandode, Rakesh K.; Ghate, Hemant V.; Patole, Milind S.; Werren, John H.

2012-01-01

Members of the genus Wolbachia are intracellular bacteria that are widespread in arthropods and establish diverse symbiotic associations with their hosts, ranging from mutualism to parasitism. Here we present the first detailed analyses of Wolbachia in butterflies from India with screening of 56 species. Twenty-nine species (52%) representing five families were positive for Wolbachia. This is the first report of Wolbachia infection in 27 of the 29 species; the other two were reported previously. This study also provides the first evidence of infection in the family Papilionidae. A striking diversity was observed among Wolbachia strains in butterfly hosts based on five multilocus sequence typing (MLST) genes, with 15 different sequence types (STs). Thirteen STs are new to the MLST database, whereas ST41 and ST125 were reported earlier. Some of the same host species from this study carried distinctly different Wolbachia strains, whereas the same or different butterfly hosts also harbored closely related Wolbachia strains. Butterfly-associated STs in the Indian sample originated by recombination and point mutation, further supporting the role of both processes in generating Wolbachia diversity. Recombination was detected only among the STs in this study and not in those from the MLST database. Most of the strains were remarkably similar in their wsp genotype, despite divergence in MLST. Only two wsp alleles were found among 25 individuals with complete hypervariable region (HVR) peptide profiles. Although both wsp and MLST show variability, MLST gives better separation between the strains. Completely different STs were characterized for the individuals sharing the same wsp alleles. PMID:22504801

Both XPD alleles contribute to the phenotype of compound heterozygote xeroderma pigmentosum patients

PubMed Central

Ueda, Takahiro; Compe, Emmanuel; Catez, Philippe; Kraemer, Kenneth H.

2009-01-01

Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH result in the rare recessive genetic disorder xeroderma pigmentosum (XP). Many XP patients are compound heterozygotes with a “causative” XPD point mutation R683W and different second mutant alleles, considered “null alleles.” However, there is marked clinical heterogeneity (including presence or absence of skin cancers or neurological degeneration) in these XPD/R683W patients, thus suggesting a contribution of the second allele. Here, we report XP patients carrying XPD/R683W and a second XPD allele either XPD/Q452X, /I455del, or /199insPP. We performed a systematic study of the effect of these XPD mutations on several enzymatic functions of TFIIH and found that each mutation exhibited unique biochemical properties. Although all the mutations inhibited the nucleotide excision repair (NER) by disturbing the XPD helicase function, each of them disrupted specific molecular steps during transcription: XPD/Q452X hindered the transactivation process, XPD/I455del disturbed RNA polymerase II phosphorylation, and XPD/199insPP inhibited kinase activity of the cdk7 subunit of TFIIH. The broad range and severity of clinical features in XP patients arise from a broad set of deficiencies in NER and transcription that result from the combination of mutations found on both XPD alleles. PMID:19934020

Clonal Population Structure of Pseudomonas stutzeri, a Species with Exceptional Genetic Diversity

PubMed Central

Rius, Núria; Fusté, M. Carme; Guasp, Caterina; Lalucat, Jorge; Lorén, José G.

2001-01-01

Genetic diversity and genetic relationships among 42 Pseudomonas stutzeri strains belonging to several genomovars and isolated from different sources were investigated in an examination of 20 metabolic enzymes by multilocus enzyme electrophoresis analysis. Forty-two distinct allele profiles were identified, indicating that all multilocus genotypes were represented by a single strain. All 20 loci were exceptionally polymorphic, with an average of 15.9 alleles per locus. To the best of our knowledge, this P. stutzeri sample exhibited the highest mean genetic diversity (H = 0.876) found to date in all bacterial species studied by multilocus enzyme electrophoresis. A high frequency of occurrence of null alleles was identified. The index of association (IA) for the P. stutzeri strains analyzed was 1.10. The IA values were always significantly different from zero for all subgroups studied, including clinical and environmental isolates and strains classified as genomovar 1. These results suggest that the population structure of P. stutzeri is strongly clonal, indicating that there is no significant level of assortative recombination that might destroy linkage disequilibrium. PMID:11133969

MS205 Minisatellite Diversity in Basques: Evidence for a Pre-Neolithic Component

PubMed Central

Alonso, Santos; Armour, John A.L.

1998-01-01

A number of studies have suggested that Basques might be a relic of Mesolithic Europeans who escaped much of the homogenization brought about by the Neolithic expansion. In an attempt to add new insights into this hypothesis, MS205 minisatellite diversity has been investigated by Minisatellite Variant Repeat (MVR) analysis in a sample of >100 autochthonous individuals from the Basque Country, along with 24 Castilian (N. Spain) and 23 individuals from the United Kingdom. These populations were examined in the context of the available world database for MS205 alleles. To deduce the similarities among populations, we have applied a phylogenetic approach that takes into account similarity between alleles. The variability of these populations seems to be a subset of the greater and presumably older African diversity, as has been suggested previously for non-Africans. Within non-Africans, Basques seem to cluster with other Northern European populations; however, some apparently Basque-specific alleles can be dated back to post-Aurignacian times, supporting the continuity of some lineages of this population since the Upper Paleolithic period. PMID:9872983

Mapping genetic diversity of cherimoya (Annona cherimola Mill.): application of spatial analysis for conservation and use of plant genetic resources.

PubMed

Zonneveld, Maarten van; Scheldeman, Xavier; Escribano, Pilar; Viruel, María A; Van Damme, Patrick; Garcia, Willman; Tapia, César; Romero, José; Sigueñas, Manuel; Hormaza, José I

2012-01-01

There is a growing call for inventories that evaluate geographic patterns in diversity of plant genetic resources maintained on farm and in species' natural populations in order to enhance their use and conservation. Such evaluations are relevant for useful tropical and subtropical tree species, as many of these species are still undomesticated, or in incipient stages of domestication and local populations can offer yet-unknown traits of high value to further domestication. For many outcrossing species, such as most trees, inbreeding depression can be an issue, and genetic diversity is important to sustain local production. Diversity is also crucial for species to adapt to environmental changes. This paper explores the possibilities of incorporating molecular marker data into Geographic Information Systems (GIS) to allow visualization and better understanding of spatial patterns of genetic diversity as a key input to optimize conservation and use of plant genetic resources, based on a case study of cherimoya (Annona cherimola Mill.), a Neotropical fruit tree species. We present spatial analyses to (1) improve the understanding of spatial distribution of genetic diversity of cherimoya natural stands and cultivated trees in Ecuador, Bolivia and Peru based on microsatellite molecular markers (SSRs); and (2) formulate optimal conservation strategies by revealing priority areas for in situ conservation, and identifying existing diversity gaps in ex situ collections. We found high levels of allelic richness, locally common alleles and expected heterozygosity in cherimoya's putative centre of origin, southern Ecuador and northern Peru, whereas levels of diversity in southern Peru and especially in Bolivia were significantly lower. The application of GIS on a large microsatellite dataset allows a more detailed prioritization of areas for in situ conservation and targeted collection across the Andean distribution range of cherimoya than previous studies could do, i.e. at

Mapping Genetic Diversity of Cherimoya (Annona cherimola Mill.): Application of Spatial Analysis for Conservation and Use of Plant Genetic Resources

PubMed Central

van Zonneveld, Maarten; Scheldeman, Xavier; Escribano, Pilar; Viruel, María A.; Van Damme, Patrick; Garcia, Willman; Tapia, César; Romero, José; Sigueñas, Manuel; Hormaza, José I.

2012-01-01

There is a growing call for inventories that evaluate geographic patterns in diversity of plant genetic resources maintained on farm and in species' natural populations in order to enhance their use and conservation. Such evaluations are relevant for useful tropical and subtropical tree species, as many of these species are still undomesticated, or in incipient stages of domestication and local populations can offer yet-unknown traits of high value to further domestication. For many outcrossing species, such as most trees, inbreeding depression can be an issue, and genetic diversity is important to sustain local production. Diversity is also crucial for species to adapt to environmental changes. This paper explores the possibilities of incorporating molecular marker data into Geographic Information Systems (GIS) to allow visualization and better understanding of spatial patterns of genetic diversity as a key input to optimize conservation and use of plant genetic resources, based on a case study of cherimoya (Annona cherimola Mill.), a Neotropical fruit tree species. We present spatial analyses to (1) improve the understanding of spatial distribution of genetic diversity of cherimoya natural stands and cultivated trees in Ecuador, Bolivia and Peru based on microsatellite molecular markers (SSRs); and (2) formulate optimal conservation strategies by revealing priority areas for in situ conservation, and identifying existing diversity gaps in ex situ collections. We found high levels of allelic richness, locally common alleles and expected heterozygosity in cherimoya's putative centre of origin, southern Ecuador and northern Peru, whereas levels of diversity in southern Peru and especially in Bolivia were significantly lower. The application of GIS on a large microsatellite dataset allows a more detailed prioritization of areas for in situ conservation and targeted collection across the Andean distribution range of cherimoya than previous studies could do, i.e. at

Genetic Diversity and Population Structure of Theileria annulata in Oman

PubMed Central

Al-Hamidhi, Salama; H. Tageldin, Mohammed.; Weir, William; Al-Fahdi, Amira; Johnson, Eugene H.; Bobade, Patrick; Alqamashoui, Badar; Beja-Pereira, Albano; Thompson, Joanne; Kinnaird, Jane; Shiels, Brian; Tait, Andy; Babiker, Hamza

2015-01-01

Background Theileriosis, caused by a number of species within the genus Theileria, is a common disease of livestock in Oman. It is a major constraint to the development of the livestock industry due to a high rate of morbidity and mortality in both cattle and sheep. Since little is currently known about the genetic diversity of the parasites causing theileriosis in Oman, the present study was designed to address this issue with specific regard to T. annulata in cattle. Methods Blood samples were collected from cattle from four geographically distinct regions in Oman for genetic analysis of the Theileria annulata population. Ten genetic markers (micro- and mini-satellites) representing all four chromosomes of T. annulata were applied to these samples using a combination of PCR amplification and fragment analysis. The resultant genetic data was analysed to provide a first insight into the structure of the T. annulata population in Oman. Results We applied ten micro- and mini-satellite markers to a total of 310 samples obtained from different regions (174 [56%] from Dhofar, 68 [22%] from Dhira, 44 [14.5%] from Batinah and 24 [8%] from Sharqia). A high degree of allelic diversity was observed among the four parasite populations. Expected heterozygosity for each site ranged from 0.816 to 0.854. A high multiplicity of infection was observed in individual hosts, with an average of 3.3 to 3.4 alleles per locus, in samples derived from Batinah, Dhofar and Sharqia regions. In samples from Dhira region, an average of 2.9 alleles per locus was observed. Mild but statistically significant linkage disequilibrium between pairs of markers was observed in populations from three of the four regions. In contrast, when the analysis was performed at farm level, no significant linkage disequilibrium was observed. Finally, no significant genetic differentiation was seen between the four populations, with most pair-wise FST values being less than 0.03. Slightly higher FST values (GST�

Genetic Diversity and Population Structure of Theileria annulata in Oman.

PubMed

Al-Hamidhi, Salama; H Tageldin, Mohammed; Weir, William; Al-Fahdi, Amira; Johnson, Eugene H; Bobade, Patrick; Alqamashoui, Badar; Beja-Pereira, Albano; Thompson, Joanne; Kinnaird, Jane; Shiels, Brian; Tait, Andy; Babiker, Hamza

2015-01-01

Theileriosis, caused by a number of species within the genus Theileria, is a common disease of livestock in Oman. It is a major constraint to the development of the livestock industry due to a high rate of morbidity and mortality in both cattle and sheep. Since little is currently known about the genetic diversity of the parasites causing theileriosis in Oman, the present study was designed to address this issue with specific regard to T. annulata in cattle. Blood samples were collected from cattle from four geographically distinct regions in Oman for genetic analysis of the Theileria annulata population. Ten genetic markers (micro- and mini-satellites) representing all four chromosomes of T. annulata were applied to these samples using a combination of PCR amplification and fragment analysis. The resultant genetic data was analysed to provide a first insight into the structure of the T. annulata population in Oman. We applied ten micro- and mini-satellite markers to a total of 310 samples obtained from different regions (174 [56%] from Dhofar, 68 [22%] from Dhira, 44 [14.5%] from Batinah and 24 [8%] from Sharqia). A high degree of allelic diversity was observed among the four parasite populations. Expected heterozygosity for each site ranged from 0.816 to 0.854. A high multiplicity of infection was observed in individual hosts, with an average of 3.3 to 3.4 alleles per locus, in samples derived from Batinah, Dhofar and Sharqia regions. In samples from Dhira region, an average of 2.9 alleles per locus was observed. Mild but statistically significant linkage disequilibrium between pairs of markers was observed in populations from three of the four regions. In contrast, when the analysis was performed at farm level, no significant linkage disequilibrium was observed. Finally, no significant genetic differentiation was seen between the four populations, with most pair-wise FST values being less than 0.03. Slightly higher FST values (GST' = 0.075, θ = 0.07) were

Allele-specific locus binding and genome editing by CRISPR at the p16INK4a locus.

PubMed

Fujita, Toshitsugu; Yuno, Miyuki; Fujii, Hodaka

2016-07-28

The clustered regularly interspaced short palindromic repeats (CRISPR) system has been adopted for a wide range of biological applications including genome editing. In some cases, dissection of genome functions requires allele-specific genome editing, but the use of CRISPR for this purpose has not been studied in detail. In this study, using the p16INK4a gene in HCT116 as a model locus, we investigated whether chromatin states, such as CpG methylation, or a single-nucleotide gap form in a target site can be exploited for allele-specific locus binding and genome editing by CRISPR in vivo. First, we showed that allele-specific locus binding and genome editing could be achieved by targeting allele-specific CpG-methylated regions, which was successful for one, but not all guide RNAs. In this regard, molecular basis underlying the success remains elusive at this stage. Next, we demonstrated that an allele-specific single-nucleotide gap form could be employed for allele-specific locus binding and genome editing by CRISPR, although it was important to avoid CRISPR tolerance of a single nucleotide mismatch brought about by mismatched base skipping. Our results provide information that might be useful for applications of CRISPR in studies of allele-specific functions in the genomes.

Estimating Time to the Common Ancestor for a Beneficial Allele

PubMed Central

Smith, Joel; Coop, Graham; Stephens, Matthew; Novembre, John

2018-01-01

Abstract The haplotypes of a beneficial allele carry information about its history that can shed light on its age and the putative cause for its increase in frequency. Specifically, the signature of an allele’s age is contained in the pattern of variation that mutation and recombination impose on its haplotypic background. We provide a method to exploit this pattern and infer the time to the common ancestor of a positively selected allele following a rapid increase in frequency. We do so using a hidden Markov model which leverages the length distribution of the shared ancestral haplotype, the accumulation of derived mutations on the ancestral background, and the surrounding background haplotype diversity. Using simulations, we demonstrate how the inclusion of information from both mutation and recombination events increases accuracy relative to approaches that only consider a single type of event. We also show the behavior of the estimator in cases where data do not conform to model assumptions, and provide some diagnostics for assessing and improving inference. Using the method, we analyze population-specific patterns in the 1000 Genomes Project data to estimate the timing of adaptation for several variants which show evidence of recent selection and functional relevance to diet, skin pigmentation, and morphology in humans. PMID:29361025

Genetic Adaptation to Climate in White Spruce Involves Small to Moderate Allele Frequency Shifts in Functionally Diverse Genes

PubMed Central

Hornoy, Benjamin; Pavy, Nathalie; Gérardi, Sébastien; Beaulieu, Jean; Bousquet, Jean

2015-01-01

Understanding the genetic basis of adaptation to climate is of paramount importance for preserving and managing genetic diversity in plants in a context of climate change. Yet, this objective has been addressed mainly in short-lived model species. Thus, expanding knowledge to nonmodel species with contrasting life histories, such as forest trees, appears necessary. To uncover the genetic basis of adaptation to climate in the widely distributed boreal conifer white spruce (Picea glauca), an environmental association study was conducted using 11,085 single nucleotide polymorphisms representing 7,819 genes, that is, approximately a quarter of the transcriptome. Linear and quadratic regressions controlling for isolation-by-distance, and the Random Forest algorithm, identified several dozen genes putatively under selection, among which 43 showed strongest signals along temperature and precipitation gradients. Most of them were related to temperature. Small to moderate shifts in allele frequencies were observed. Genes involved encompassed a wide variety of functions and processes, some of them being likely important for plant survival under biotic and abiotic environmental stresses according to expression data. Literature mining and sequence comparison also highlighted conserved sequences and functions with angiosperm homologs. Our results are consistent with theoretical predictions that local adaptation involves genes with small frequency shifts when selection is recent and gene flow among populations is high. Accordingly, genetic adaptation to climate in P. glauca appears to be complex, involving many independent and interacting gene functions, biochemical pathways, and processes. From an applied perspective, these results shall lead to specific functional/association studies in conifers and to the development of markers useful for the conservation of genetic resources. PMID:26560341

Nucleation and Spread of an Invasive Allele

NASA Astrophysics Data System (ADS)

Korniss, Gyorgy; Caraco, Thomas

2005-03-01

We analyze a prototypical discrete spatial model for the spread of an invasive allele when individuals compete preemptively for common limiting resources. Initially, the population is genetically monomorphic with the resident allele at high density. The invasive allele is introduced through rare, but recurrent, mutation. The mutant allele is the better competitor (has an individual-level advantage) but its spread is limited by the local availability of resources. We find that each successful introduction of the mutant leads to strong spatial clustering. Spatial patterns in simulation resemble nucleation and subsequent growth, articulately described by Avrami's law in sufficiently large systemsootnotetextG. Korniss and T. Caraco, J. Theor. Biol. (in press, 2004); http://www.rpi.edu/ korniss/Research/JTB04.pdf.

Genetic diversity of avenin-like b genes in Aegilops tauschii Coss.

PubMed

Cao, Dong; Wang, Hongxia; Zhang, Bo; Liu, Baolong; Liu, Dengcai; Chen, Wenjie; Zhang, Huaigang

2018-02-01

Avenin-like storage proteins influence the rheological properties and processing quality in common wheat, and the discovery of new alleles will benefit wheat quality improvement. In this study, 13 avenin-like b alleles (TaALPb7D-A-M) were discovered in 108 Aegilops tauschii Coss. accessions. Ten alleles were reported for the first time, while the remaining three alleles were the same as alleles in other species. A total of 15 nucleotide changes were detected in the 13 alleles, resulting in only 11 amino acid changes because of synonymous mutations. Alleles TaALPb7D-E, TaALPb7D-G, and TaALPb7D-J encoded the same protein. These polymorphic sites existed in the N-terminus, Repetitive region (Left), Repetitive region (Right) and C-terminus domains, with no polymorphisms in the signal peptide sequence nor in those encoding the 18 conserved cysteine residues. Phylogenetic analysis divided the TaALPb7Ds into four clades. The Ae. tauschii alleles were distributed in all four clades, while the alleles derived from common wheat, TaALPb7D-G and TaALPb7D-C, belonged to clade III and IV, respectively. Alleles TaALPb7D-G and TaALPb7D-C were the most widely distributed, being present in nine and six countries, respectively. Iran and Turkey exhibited the highest genetic diversity with respect to TaALPb7D alleles, accessions from these countries carrying seven and six alleles, respectively, which implied that these countries were the centers of origin of the avenin-like b gene. The new alleles discovered and the phylogenetic analysis of avenin-like b genes will provide breeding materials and a theoretical basis for wheat quality improvement.

Several Different Lactase Persistence Associated Alleles and High Diversity of the Lactase Gene in the Admixed Brazilian Population

PubMed Central

Friedrich, Deise C.; Santos, Sidney E. B.; Ribeiro-dos-Santos, Ândrea K. C.; Hutz, Mara H.

2012-01-01

Adult-type hypolactasia is a common phenotype caused by the lactase enzyme deficiency. The −13910 C>T polymorphism, located 14 Kb upstream of the lactase gene (LCT) in the MCM6 gene was associated with lactase persistence (LP) in Europeans. This polymorphism is rare in Africa but several other variants associated with lactase persistence were observed in Africans. The aims of this study were to identify polymorphisms in the MCM6 region associated with the lactase persistence phenotype and to determine the distribution of LCT gene haplotypes in 981 individuals from North, Northeast and South Brazil. These polymorphisms were genotyped by PCR based methods and sequencing. The −13779*C,−13910*T, −13937*A, −14010*C, −14011*T LP alleles previously described in the MCM6 gene region that acts as an enhancer for the LCT gene were identified in Brazilians. The most common LP allele was −13910*T. Its frequency was highly correlated with European ancestry in the Brazilian populations investigated. The −13910*T was higher (0.295) in southern Brazilians of European ancestry and lower (0.175) in the Northern admixed population. LCT haplotypes were derived from the 10 LCT SNPs genotyped. Overall twenty six haplotypes previously described were identified in the four Brazilian populations studied. The Multidimensional Scaling analysis showed that Belém, in the north, was closer to Amerindians. Northeastern and southern Afro-descendants were more related with Bantu-speaking South Africans whereas the Southern population with European ancestry grouped with Southern and Northern Europeans. This study shows a high variability considering the number of LCT haplotypes observed. Due to the highly admixed nature of the Brazilian populations, the diagnosis of hypolactasia in Brazil, based only in the investigation of the −13910*T allele is an oversimplification. PMID:23029545

Detection of new HLA-DPB1 alleles generated by interallelic gene conversion using PCR amplification of DPB1 second exon sequences from sperm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erlich, H.; Zangenberg, G.; Bugawan, T.

The rate at which allelic diversity at the HLA class I and class II loci evolves has been the subject of considerable controversy as have the mechanisms which generate new alleles. The patchwork pattern of polymorphism, particularly within the second exon of the HLA-DPB1 locus where the polymorphic sequence motifs are localized to 6 discrete regions, is consistent with the hypothesis that much of the allelic sequence variation may have been generated by segmental exchange (gene conversion). To measure the rate of new DPB1 variant generation, we have developed a strategy in which DPB1 second exon sequences are amplified frommore » pools of FACS-sorted sperm (n=50) from a heterozygous sperm donor. Pools of sperm from these heterozygous individuals are amplified with an allele-specific primer for one allele and analyzed with sequence-specific oligonucleotide probes (SSOP) complementary to the other allele. This screening procedure, which is capable of detecting a single variant molecule in a pool of parental alleles, allows the identification of new variants that have been generated by recombination and/or gene conversion between the two parental alleles. To control for potential PCR artifacts, the same screening procedure was carried out with mixtures of sperm from DPB1 *0301/*0301 and DPB1 *0401/ 0401 individuals. Pools containing putative new variants DPB1 alleles were analyzed further by cloning into M13 and sequencing the M13 clones. Our current estimate is that about 1/10,000 sperm from these heterozygous individuals represents a new DPB1 allele generated by micro-gene conversion within the second exon.« less

Are ‘Endurance’ Alleles ‘Survival’ Alleles? Insights from the ACTN3 R577X Polymorphism

PubMed Central

Fiuza-Luces, Carmen; Ruiz, Jonatan R.; Rodríguez-Romo, Gabriel; Santiago, Catalina; Gómez-Gallego, Félix; Yvert, Thomas; Cano-Nieto, Amalia; Garatachea, Nuria

2011-01-01

Exercise phenotypes have played a key role for ensuring survival over human evolution. We speculated that some genetic variants that influence exercise phenotypes could be associated with exceptional survival (i.e. reaching ≥100years of age). Owing to its effects on muscle structure/function, a potential candidate is the Arg(R)577Ter(X) polymorphism (rs1815739) in ACTN3, the structural gene encoding the skeletal muscle protein α-actinin-3. We compared the ACTN3 R577X genotype/allele frequencies between the following groups of ethnically-matched (Spanish) individuals: centenarians (cases, n = 64; 57 female; age range: 100–108 years), young healthy controls (n = 283, 67 females, 216 males; 21±2 years), and humans who are at the two end-points of exercise capacity phenotypes, i.e. muscle endurance (50 male professional road cyclists) and muscle power (63 male jumpers/sprinters). Although there were no differences in genotype/allele frequencies between centenarians (RR:28.8%; RX:47.5%; XX:23.7%), and controls (RR:31.8%; RX:49.8%; XX:18.4%) or endurance athletes (RR:28.0%; RX:46%; XX:26.0%), we observed a significantly higher frequency of the X allele (P = 0.019) and XX genotype (P = 0.011) in centenarians compared with power athletes (RR:47.6%; RX:36.5%;XX:15.9%). Notably, the frequency of the null XX (α-actinin-3 deficient) genotype in centenarians was the highest ever reported in non-athletic Caucasian populations. In conclusion, despite there were no significant differences with the younger, control population, overall the ACTN3 genotype of centenarians resembles that of world-class elite endurance athletes and differs from that of elite power athletes. Our preliminary data would suggest a certain ‘survival’ advantage brought about by α-actinin-3 deficiency and the ‘endurance’/oxidative muscle phenotype that is commonly associated with this condition. PMID:21407828

High-efficiency genome editing and allele replacement in prototrophic and wild strains of Saccharomyces.

PubMed

Alexander, William G; Doering, Drew T; Hittinger, Chris Todd

2014-11-01

Current genome editing techniques available for Saccharomyces yeast species rely on auxotrophic markers, limiting their use in wild and industrial strains and species. Taking advantage of the ancient loss of thymidine kinase in the fungal kingdom, we have developed the herpes simplex virus thymidine kinase gene as a selectable and counterselectable marker that forms the core of novel genome engineering tools called the H: aploid E: ngineering and R: eplacement P: rotocol (HERP) cassettes. Here we show that these cassettes allow a researcher to rapidly generate heterogeneous populations of cells with thousands of independent chromosomal allele replacements using mixed PCR products. We further show that the high efficiency of this approach enables the simultaneous replacement of both alleles in diploid cells. Using these new techniques, many of the most powerful yeast genetic manipulation strategies are now available in wild, industrial, and other prototrophic strains from across the diverse Saccharomyces genus. Copyright © 2014 by the Genetics Society of America.

Assigning breed origin to alleles in crossbred animals.

PubMed

Vandenplas, Jérémie; Calus, Mario P L; Sevillano, Claudia A; Windig, Jack J; Bastiaansen, John W M

2016-08-22

For some species, animal production systems are based on the use of crossbreeding to take advantage of the increased performance of crossbred compared to purebred animals. Effects of single nucleotide polymorphisms (SNPs) may differ between purebred and crossbred animals for several reasons: (1) differences in linkage disequilibrium between SNP alleles and a quantitative trait locus; (2) differences in genetic backgrounds (e.g., dominance and epistatic interactions); and (3) differences in environmental conditions, which result in genotype-by-environment interactions. Thus, SNP effects may be breed-specific, which has led to the development of genomic evaluations for crossbred performance that take such effects into account. However, to estimate breed-specific effects, it is necessary to know breed origin of alleles in crossbred animals. Therefore, our aim was to develop an approach for assigning breed origin to alleles of crossbred animals (termed BOA) without information on pedigree and to study its accuracy by considering various factors, including distance between breeds. The BOA approach consists of: (1) phasing genotypes of purebred and crossbred animals; (2) assigning breed origin to phased haplotypes; and (3) assigning breed origin to alleles of crossbred animals based on a library of assigned haplotypes, the breed composition of crossbred animals, and their SNP genotypes. The accuracy of allele assignments was determined for simulated datasets that include crosses between closely-related, distantly-related and unrelated breeds. Across these scenarios, the percentage of alleles of a crossbred animal that were correctly assigned to their breed origin was greater than 90 %, and increased with increasing distance between breeds, while the percentage of incorrectly assigned alleles was always less than 2 %. For the remaining alleles, i.e. 0 to 10 % of all alleles of a crossbred animal, breed origin could not be assigned. The BOA approach accurately assigns

Spatio-temporal dynamics of genetic diversity in Sorghum bicolor in Niger.

PubMed

Deu, Monique; Sagnard, F; Chantereau, J; Calatayud, C; Vigouroux, Y; Pham, J L; Mariac, C; Kapran, I; Mamadou, A; Gérard, B; Ndjeunga, J; Bezançon, G

2010-05-01

The dynamics of crop genetic diversity need to be assessed to draw up monitoring and conservation priorities. However, few surveys have been conducted in centres of diversity. Sub-Saharan Africa is the centre of origin of sorghum. Most Sahel countries have been faced with major human, environmental and social changes in recent decades, which are suspected to cause genetic erosion. Sorghum is the second staple cereal in Niger, a centre of diversity for this crop. Niger was submitted to recurrent drought period and to major social changes during these last decades. We report here on a spatio-temporal analysis of sorghum genetic diversity, conducted in 71 villages covering the rainfall gradient and range of agro-ecological conditions in Niger's agricultural areas. We used 28 microsatellite markers and applied spatial and genetic clustering methods to investigate change in genetic diversity over a 26-year period (1976-2003). Global genetic differentiation between the two collections was very low (F (st) = 0.0025). Most of the spatial clusters presented no major differentiation, as measured by F (st), and showed stability or an increase in allelic richness, except for two of them located in eastern Niger. The genetic clusters identified by Bayesian analysis did not show a major change between the two collections in the distribution of accessions between them or in their spatial location. These results suggest that farmers' management has globally preserved sorghum genetic diversity in Niger.

Diversity of the Cronobacter Genus as Revealed by Multilocus Sequence Typing

PubMed Central

Joseph, S.; Sonbol, H.; Hariri, S.; Desai, P.; McClelland, M.

2012-01-01

Cronobacter (previously known as Enterobacter sakazakii) is a diverse bacterial genus consisting of seven species: C. sakazakii, C. malonaticus, C. turicensis, C. universalis, C. muytjensii, C. dublinensis, and C. condimenti. In this study, we have used a multilocus sequence typing (MLST) approach employing the alleles of 7 genes (atpD, fusA, glnS, gltB, gyrB, infB, and ppsA; total length, 3,036 bp) to investigate the phylogenetic relationship of 325 Cronobacter species isolates. Strains were chosen on the basis of their species, geographic and temporal distribution, source, and clinical outcome. The earliest strain was isolated from milk powder in 1950, and the earliest clinical strain was isolated in 1953. The existence of seven species was supported by MLST. Intraspecific variation ranged from low diversity in C. sakazakii to extensive diversity within some species, such as C. muytjensii and C. dublinensis, including evidence of gene conversion between species. The predominant species from clinical sources was found to be C. sakazakii. C. sakazakii sequence type 4 (ST4) was the predominant sequence type of cerebral spinal fluid isolates from cases of meningitis. PMID:22785185

Extensive variation between tissues in allele specific expression in an outbred mammal.

PubMed

Chamberlain, Amanda J; Vander Jagt, Christy J; Hayes, Benjamin J; Khansefid, Majid; Marett, Leah C; Millen, Catriona A; Nguyen, Thuy T T; Goddard, Michael E

2015-11-23

allele expression imbalance reversed between tissues. For example the gene SPTY2D1 showed almost complete paternal allele expression in kidney and thymus, and almost complete maternal allele expression in the brain caudal lobe and brain cerebellum. Mono allelic expression (MAE) was common, with 1349 of 4856 genes (28 %) tested with more than one heterozygous SNP showing MAE. Across all tissues, 54.17 % of all genes with ASE favoured the paternal allele. Genes that are closely linked on the chromosome were more likely to show higher expression of the same allele (paternal or maternal) than expected by chance. We identified several long runs of neighbouring genes that showed either paternal or maternal ASE, one example was five adjacent genes (GIMAP8, GIMAP7 copy1, GIMAP4, GIMAP7 copy 2 and GIMAP5) that showed almost exclusive paternal expression in brain caudal lobe. Investigating the extent of ASE across 18 bovine tissues in one cow and two tissues in 20 cows demonstrated 1) ASE is pervasive in cattle, 2) the ASE is often MAE but ranges from MAE to slight overexpression of the major allele, 3) the ASE is most often tissue specific and that more than half the time displays divergent allele specific expression patterns across tissues, 4) across all genes there is a slight bias towards expression of the paternal allele and 5) genes expressing the same parental allele are clustered together more than expected by chance, and there are several runs of large numbers of genes expressing the same parental allele.

Use of allele scores as instrumental variables for Mendelian randomization

PubMed Central

Burgess, Stephen; Thompson, Simon G

2013-01-01

Background An allele score is a single variable summarizing multiple genetic variants associated with a risk factor. It is calculated as the total number of risk factor-increasing alleles for an individual (unweighted score), or the sum of weights for each allele corresponding to estimated genetic effect sizes (weighted score). An allele score can be used in a Mendelian randomization analysis to estimate the causal effect of the risk factor on an outcome. Methods Data were simulated to investigate the use of allele scores in Mendelian randomization where conventional instrumental variable techniques using multiple genetic variants demonstrate ‘weak instrument’ bias. The robustness of estimates using the allele score to misspecification (for example non-linearity, effect modification) and to violations of the instrumental variable assumptions was assessed. Results Causal estimates using a correctly specified allele score were unbiased with appropriate coverage levels. The estimates were generally robust to misspecification of the allele score, but not to instrumental variable violations, even if the majority of variants in the allele score were valid instruments. Using a weighted rather than an unweighted allele score increased power, but the increase was small when genetic variants had similar effect sizes. Naive use of the data under analysis to choose which variants to include in an allele score, or for deriving weights, resulted in substantial biases. Conclusions Allele scores enable valid causal estimates with large numbers of genetic variants. The stringency of criteria for genetic variants in Mendelian randomization should be maintained for all variants in an allele score. PMID:24062299

The Pleiotropic Phenotype of Apc Mutations in the Mouse: Allele Specificity and Effects of the Genetic Background

PubMed Central

Halberg, Richard B.; Chen, Xiaodi; Amos-Landgraf, James M.; White, Alanna; Rasmussen, Kristin; Clipson, Linda; Pasch, Cheri; Sullivan, Ruth; Pitot, Henry C.; Dove, William F.

2008-01-01

Familial adenomatous polyposis (FAP) is a human cancer syndrome characterized by the development of hundreds to thousands of colonic polyps and extracolonic lesions including desmoid fibromas, osteomas, epidermoid cysts, and congenital hypertrophy of the pigmented retinal epithelium. Afflicted individuals are heterozygous for mutations in the APC gene. Detailed investigations of mice heterozygous for mutations in the ortholog Apc have shown that other genetic factors strongly influence the phenotype. Here we report qualitative and quantitative modifications of the phenotype of Apc mutants as a function of three genetic variables: Apc allele, p53 allele, and genetic background. We have found major differences between the Apc alleles Min and 1638N in multiplicity and regionality of intestinal tumors, as well as in incidence of extracolonic lesions. By contrast, Min mice homozygous for either of two different knockout alleles of p53 show similar phenotypic effects. These studies illustrate the classic principle that functional genetics is enriched by assessing penetrance and expressivity with allelic series. The mouse permits study of an allelic gene series on multiple genetic backgrounds, thereby leading to a better understanding of gene action in a range of biological processes. PMID:18723878

The pleiotropic phenotype of Apc mutations in the mouse: allele specificity and effects of the genetic background.

PubMed

Halberg, Richard B; Chen, Xiaodi; Amos-Landgraf, James M; White, Alanna; Rasmussen, Kristin; Clipson, Linda; Pasch, Cheri; Sullivan, Ruth; Pitot, Henry C; Dove, William F

2008-09-01

Familial adenomatous polyposis (FAP) is a human cancer syndrome characterized by the development of hundreds to thousands of colonic polyps and extracolonic lesions including desmoid fibromas, osteomas, epidermoid cysts, and congenital hypertrophy of the pigmented retinal epithelium. Afflicted individuals are heterozygous for mutations in the APC gene. Detailed investigations of mice heterozygous for mutations in the ortholog Apc have shown that other genetic factors strongly influence the phenotype. Here we report qualitative and quantitative modifications of the phenotype of Apc mutants as a function of three genetic variables: Apc allele, p53 allele, and genetic background. We have found major differences between the Apc alleles Min and 1638N in multiplicity and regionality of intestinal tumors, as well as in incidence of extracolonic lesions. By contrast, Min mice homozygous for either of two different knockout alleles of p53 show similar phenotypic effects. These studies illustrate the classic principle that functional genetics is enriched by assessing penetrance and expressivity with allelic series. The mouse permits study of an allelic gene series on multiple genetic backgrounds, thereby leading to a better understanding of gene action in a range of biological processes.

ALEA: a toolbox for allele-specific epigenomics analysis.

PubMed

Younesy, Hamid; Möller, Torsten; Heravi-Moussavi, Alireza; Cheng, Jeffrey B; Costello, Joseph F; Lorincz, Matthew C; Karimi, Mohammad M; Jones, Steven J M

2014-04-15

The assessment of expression and epigenomic status using sequencing based methods provides an unprecedented opportunity to identify and correlate allelic differences with epigenomic status. We present ALEA, a computational toolbox for allele-specific epigenomics analysis, which incorporates allelic variation data within existing resources, allowing for the identification of significant associations between epigenetic modifications and specific allelic variants in human and mouse cells. ALEA provides a customizable pipeline of command line tools for allele-specific analysis of next-generation sequencing data (ChIP-seq, RNA-seq, etc.) that takes the raw sequencing data and produces separate allelic tracks ready to be viewed on genome browsers. The pipeline has been validated using human and hybrid mouse ChIP-seq and RNA-seq data. The package, test data and usage instructions are available online at http://www.bcgsc.ca/platform/bioinfo/software/alea CONTACT: : mkarimi1@interchange.ubc.ca or sjones@bcgsc.ca Supplementary information: Supplementary data are available at Bioinformatics online. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Selection, trans-species polymorphism, and locus identification of major histocompatibility complex class IIβ alleles of New World ranid frogs

USGS Publications Warehouse

Kiemnec-Tyburczy, Karen M.; Richmond, Jonathan Q.; Savage, Anna E.; Zamudio, Kelly R.

2010-01-01

Genes encoded by the major histocompatibility complex (MHC) play key roles in the vertebrate immune system. However, our understanding of the evolutionary processes and underlying genetic mechanisms shaping these genes is limited in many taxa, including amphibians, a group currently impacted by emerging infectious diseases. To further elucidate the evolution of the MHC in frogs (anurans) and develop tools for population genetics, we surveyed allelic diversity of the MHC class II ??1 domain in both genomic and complementary DNA of seven New World species in the genus Rana (Lithobates). To assign locus affiliation to our alleles, we used a "gene walking" technique to obtain intron 2 sequences that flanked MHC class II?? exon 2. Two distinct intron sequences were recovered, suggesting the presence of at least two class II?? loci in Rana. We designed a primer pair that successfully amplified an orthologous locus from all seven Rana species. In total, we recovered 13 alleles and documented trans-species polymorphism for four of the alleles. We also found quantitative evidence of selection acting on amino acid residues that are putatively involved in peptide binding and structural stability of the ??1 domain of anurans. Our results indicated that primer mismatch can result in polymerase chain reaction (PCR) bias, which influences the number of alleles that are recovered. Using a single locus may minimize PCR bias caused by primer mismatch, and the gene walking technique was an effective approach for generating single-copy orthologous markers necessary for future studies of MHC allelic variation in natural amphibian populations. ?? 2010 Springer-Verlag.

Range Expansion and the Origin of USA300 North American Epidemic Methicillin-Resistant Staphylococcus aureus

PubMed Central

Challagundla, Lavanya; Luo, Xiao; Tickler, Isabella A.; Coombs, Geoffrey W.; Sordelli, Daniel O.; Brown, Eric L.; Skov, Robert; Larsen, Anders Rhod; Reyes, Jinnethe; Robledo, Iraida E.; Vazquez, Guillermo J.; Rivera, Raul; Fey, Paul D.; Stevenson, Kurt; Wang, Shu-Hua; Kreiswirth, Barry N.; Mediavilla, Jose R.; Arias, Cesar A.; Planet, Paul J.; Nolan, Rathel L.; Tenover, Fred C.; Goering, Richard V.

2018-01-01

ABSTRACT The USA300 North American epidemic (USA300-NAE) clone of methicillin-resistant Staphylococcus aureus has caused a wave of severe skin and soft tissue infections in the United States since it emerged in the early 2000s, but its geographic origin is obscure. Here we use the population genomic signatures expected from the serial founder effects of a geographic range expansion to infer the origin of USA300-NAE and identify polymorphisms associated with its spread. Genome sequences from 357 isolates from 22 U.S. states and territories and seven other countries are compared. We observe two significant signatures of range expansion, including decreases in genetic diversity and increases in derived allele frequency with geographic distance from the Pennsylvania region. These signatures account for approximately half of the core nucleotide variation of this clone, occur genome wide, and are robust to heterogeneity in temporal sampling of isolates, human population density, and recombination detection methods. The potential for positive selection of a gyrA fluoroquinolone resistance allele and several intergenic regions, along with a 2.4 times higher recombination rate in a resistant subclade, is noted. These results are the first to show a pattern of genetic variation that is consistent with a range expansion of an epidemic bacterial clone, and they highlight a rarely considered but potentially common mechanism by which genetic drift may profoundly influence bacterial genetic variation. PMID:29295910

Association of the insertion allele of the common ACE gene polymorphism with type 2 diabetes mellitus among Kuwaiti cardiovascular disease patients.

PubMed

Al-Serri, Ahmad; Ismael, Fatma G; Al-Bustan, Suzanne A; Al-Rashdan, Ibrahim

2015-12-01

The D allele of the common angiotensin-converting enzyme (ACE) I/D gene polymorphism (rs4646994) predisposes to type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). However, results on which allele predisposes to disease susceptibility remain controversial in Asian populations. This study was performed to evaluate the association of the common ACE I/D gene polymorphism with both T2DM and CVD susceptibility in an Arab population. We genotyped the ACE I/D polymorphisms by direct allele-specific PCR in 183 healthy controls and 400 CVD patients with diabetes (n=204) and without (n=196). Statistical analysis comparing between the different groups were conducted using R statistic package "SNPassoc". Two genetic models were used: the additive and co-dominant models. The I allele was found to be associated with T2DM (OR=1.84, p=0.00009) after adjusting for age, sex and body mass index. However, there was no association with CVD susceptibility (p>0.05). The ACE I allele is found to be associated with T2DM; however, no association was observed with CVD. The inconsistency between studies is suggested to be attributed to genetic diversity due to the existence of sub-populations found in Asian populations. © The Author(s) 2015.

Effects of Favorable Alleles for Water-Soluble Carbohydrates at Grain Filling on Grain Weight under Drought and Heat Stresses in Wheat

PubMed Central

Chang, Xiaoping; Li, Runzhi; Jing, Ruilian

2014-01-01

Drought, heat and other abiotic stresses during grain filling can result in reductions in grain weight. Conserved water-soluble carbohydrates (WSC) at early grain filling play an important role in partial compensation of reduced carbon supply. A diverse population of 262 historical winter wheat accessions was used in the present study. There were significant correlations between 1000-grain weight (TGW) and four types of WSC, viz. (1) total WSC at the mid-grain filling stage (14 days after flowering) produced by leaves and non-leaf organs; (2) WSC contributed by current leaf assimilation during the mid-grain filling; (3) WSC in non-leaf organs at the mid-grain filling, excluding the current leaf assimilation; and (4) WSC used for respiration and remobilization during the mid-grain filling. Association and favorable allele analyses of 209 genome-wide SSR markers and the four types of WSC were conducted using a mixed linear model. Seven novel favorable WSC alleles exhibited positive individual contributions to TGW, which were verified under 16 environments. Dosage effects of pyramided favorable WSC alleles and significantly linear correlations between the number of favorable WSC alleles and TGW were observed. Our results suggested that pyramiding more favorable WSC alleles was effective for improving both WSC and grain weight in future wheat breeding programs. PMID:25036550

Characterization of a New Pm2 Allele Conferring Powdery Mildew Resistance in the Wheat Germplasm Line FG-1

PubMed Central

Ma, Pengtao; Xu, Hongxng; Li, Lihui; Zhang, Hongxia; Han, Guohao; Xu, Yunfeng; Fu, Xiaoyi; Zhang, Xiaotian; An, Diaoguo

2016-01-01

Powdery mildew has a negative impact on wheat production. Novel host resistance increases the diversity of resistance genes and helps to control the disease. In this study, wheat line FG-1 imported from France showed a high level of powdery mildew resistance at both the seedling and adult stages. An F2 population and F2:3 families from the cross FG-1 × Mingxian 169 both fit Mendelian ratios for a single dominant resistance gene when tested against multiple avirulent Blumeria tritici f. sp. tritici (Bgt) races. This gene was temporarily designated PmFG. PmFG was mapped on the multi-allelic Pm2 locus of chromosome 5DS using seven SSR, 10 single nucleotide polymorphism (SNP)-derived and two SCAR markers with the flanking markers Xbwm21/Xcfd81/Xscar112 (distal) and Xbwm25 (proximal) at 0.3 and 0.5 cM being the closest. Marker SCAR203 co-segregated with PmFG. Allelism tests between PmFG and documented Pm2 alleles confirmed that PmFG was allelic with Pm2. Line FG-1 produced a significantly different reaction pattern compared to other lines with genes at or near Pm2 when tested against 49 Bgt isolates. The PmFG-linked marker alleles detected by the SNP-derived markers revealed significant variation between FG-1 and other lines with genes at or near Pm2. It was concluded that PmFG is a new allele at the Pm2 locus. Data from seven closely linked markers tested on 31 wheat cultivars indicated opportunities for marker-assisted pyramiding of this gene with other genes for powdery mildew resistance and additional traits. PMID:27200022

Genetic diversity of merozoite surface protein-2 in Plasmodium falciparum isolates from Aceh province, Indonesia

NASA Astrophysics Data System (ADS)

Jamil, K. F.; Supargiyono, S.; Syafruddin, D.; Pratama, N.; Silvy, S.

2018-03-01

Estimated 3.3 million Indonesian population were infected with malaria. However, extensive genetic polymorphism of the field isolates MSP-2 of P. falciparum represents a major obstacle for the development of malaria treatment. The aim of this study to investigate the genetic diversity of MSP-2 genotype in field isolates of P. falciparum collected in Aceh Province. A total of 90 patients enrolled in this study who were selected from positive malaria from eleven district Hospitals in Aceh from 2013-2015. Data was collected by anamnesis, complete physical examination and laboratory tests for MSP-2. All protocol to diagnose malaria assigned following the WHO 2010 guideline. All samples were stored in Eijkman Biology Molecular Institute, Jakarta.Among 90 samples were 57.7% male and 42.3% female with the most cases ages between 21-30 years old. Allele typing analysis displayed the polymorphic nature of P. falciparum. The MSP-2 have two alleles, 62.2% (56/90) for FC27 type and 58.9% (53/90) for 3D7 type and 21.2% (19/90) for mixed FC27 and 3D7 infection were identified. Diverse allele types from Aceh Province was identified in MSP-2 P. falciparum patients; there is the almost similar number of patients infected with both allele. A moderate level of the mixed allele was also observed.

Deducing the pathogenic contribution of recessive ABCA4 alleles in an outbred population.

PubMed

Schindler, Emily I; Nylen, Erik L; Ko, Audrey C; Affatigato, Louisa M; Heggen, Andrew C; Wang, Kai; Sheffield, Val C; Stone, Edwin M

2010-10-01

Accurate prediction of the pathogenic effects of specific genotypes is important for the design and execution of clinical trials as well as for meaningful counseling of individual patients. However, for many autosomal recessive diseases, it can be difficult to deduce the relative pathogenic contribution of individual alleles because relatively few affected individuals share the same two disease-causing variations. In this study, we used multiple regression analysis to estimate the pathogenicity of specific alleles of ABCA4 in patients with retinal phenotypes ranging from Stargardt disease to retinitis pigmentosa. This analysis revealed quantitative allelic effects on two aspects of the visual phenotype, visual acuity (P < 10(-3)) and visual field (P < 10(-7)). Discordance between visual acuity and visual field in individual patients suggests the existence of at least two non-ABCA4 modifying factors. The findings of this study will facilitate the discovery of factors that modify ABCA4 disease and will also aid in the optimal selection of subjects for clinical trials of new therapies.

Schizophrenia and neurotrophin-3 alleles.

PubMed

Jŏnsson, E; Brené, S; Zhang, X R; Nimgaonkar, V L; Tylec, A; Schalling, M; Sedvall, G

1997-05-01

Studies of brain anatomy and premorbid functioning indicate that schizophrenia may be of neurodevelopmental origin. In the neurotrophic factor neurotrophin-3 (NT-3) gene, the A3/147-bp allele in a dinucleotide repeat polymorphism located in the promoter region was found to be associated with schizophrenia in a Japanese study. Another NT-3 polymorphism (Glu63Gly) indicated an association with schizophrenic patients with a putative neurodevelopmental form of the disease. We examined Swedish schizophrenic patients (n = 109) and control subjects (n = 78) for the same two NT-3 polymorphisms, as well as a third silent exonic polymorphism (at Pro55). No significant difference was found between the two groups. However, in a meta-analysis including the present and previous studies of Caucasian subjects, the A3/147-bp allele frequency was found to be significantly higher in the schizophrenic patients. In the present study, carriers of the A3/147 bp allele tended to have an earlier age of onset and to display more extrapyramidal symptoms. In the silent exonic polymorphism (at Pro55), female schizophrenic patients had higher adenine and lower guanine allele frequencies than control female subjects. Together with previous studies, the results provide some support for an association between the NT-3 gene and certain forms of schizophrenia. This warrants further investigation of NT-3 and other neurotrophic factors with additional polymorphisms and larger patient samples.

How do reproductive skew and founder group size affect genetic diversity in reintroduced populations?

PubMed

Miller, K A; Nelson, N J; Smith, H G; Moore, J A

2009-09-01

Reduced genetic diversity can result in short-term decreases in fitness and reduced adaptive potential, which may lead to an increased extinction risk. Therefore, maintaining genetic variation is important for the short- and long-term success of reintroduced populations. Here, we evaluate how founder group size and variance in male reproductive success influence the long-term maintenance of genetic diversity after reintroduction. We used microsatellite data to quantify the loss of heterozygosity and allelic diversity in the founder groups from three reintroductions of tuatara (Sphenodon), the sole living representatives of the reptilian order Rhynchocephalia. We then estimated the maintenance of genetic diversity over 400 years (approximately 10 generations) using population viability analyses. Reproduction of tuatara is highly skewed, with as few as 30% of males mating across years. Predicted losses of heterozygosity over 10 generations were low (1-14%), and populations founded with more animals retained a greater proportion of the heterozygosity and allelic diversity of their source populations and founder groups. Greater male reproductive skew led to greater predicted losses of genetic diversity over 10 generations, but only accelerated the loss of genetic diversity at small population size (<250 animals). A reduction in reproductive skew at low density may facilitate the maintenance of genetic diversity in small reintroduced populations. If reproductive skew is high and density-independent, larger founder groups could be released to achieve genetic goals for management.

Adenovirus and Herpesvirus Diversity in Free-Ranging Great Apes in the Sangha Region of the Republic of Congo

PubMed Central

Seimon, Tracie A.; Olson, Sarah H.; Lee, Kerry Jo; Rosen, Gail; Ondzie, Alain; Cameron, Kenneth; Reed, Patricia; Anthony, Simon J.; Joly, Damien O.; McAloose, Denise; Lipkin, W. Ian

2015-01-01

Infectious diseases have caused die-offs in both free-ranging gorillas and chimpanzees. Understanding pathogen diversity and disease ecology is therefore critical for conserving these endangered animals. To determine viral diversity in free-ranging, non-habituated gorillas and chimpanzees in the Republic of Congo, genetic testing was performed on great-ape fecal samples collected near Odzala-Kokoua National Park. Samples were analyzed to determine ape species, identify individuals in the population, and to test for the presence of herpesviruses, adenoviruses, poxviruses, bocaviruses, flaviviruses, paramyxoviruses, coronaviruses, filoviruses, and simian immunodeficiency virus (SIV). We identified 19 DNA viruses representing two viral families, Herpesviridae and Adenoviridae, of which three herpesviruses had not been previously described. Co-detections of multiple herpesviruses and/or adenoviruses were present in both gorillas and chimpanzees. Cytomegalovirus (CMV) and lymphocryptovirus (LCV) were found primarily in the context of co-association with each other and adenoviruses. Using viral discovery curves for herpesviruses and adenoviruses, the total viral richness in the sample population of gorillas and chimpanzees was estimated to be a minimum of 23 viruses, corresponding to a detection rate of 83%. These findings represent the first description of DNA viral diversity in feces from free-ranging gorillas and chimpanzees in or near the Odzala-Kokoua National Park and form a basis for understanding the types of viruses circulating among great apes in this region. PMID:25781992

Adenovirus and herpesvirus diversity in free-ranging great apes in the Sangha region of the Republic Of Congo.

PubMed

Seimon, Tracie A; Olson, Sarah H; Lee, Kerry Jo; Rosen, Gail; Ondzie, Alain; Cameron, Kenneth; Reed, Patricia; Anthony, Simon J; Joly, Damien O; Karesh, William B; McAloose, Denise; Lipkin, W Ian

2015-01-01

Infectious diseases have caused die-offs in both free-ranging gorillas and chimpanzees. Understanding pathogen diversity and disease ecology is therefore critical for conserving these endangered animals. To determine viral diversity in free-ranging, non-habituated gorillas and chimpanzees in the Republic of Congo, genetic testing was performed on great-ape fecal samples collected near Odzala-Kokoua National Park. Samples were analyzed to determine ape species, identify individuals in the population, and to test for the presence of herpesviruses, adenoviruses, poxviruses, bocaviruses, flaviviruses, paramyxoviruses, coronaviruses, filoviruses, and simian immunodeficiency virus (SIV). We identified 19 DNA viruses representing two viral families, Herpesviridae and Adenoviridae, of which three herpesviruses had not been previously described. Co-detections of multiple herpesviruses and/or adenoviruses were present in both gorillas and chimpanzees. Cytomegalovirus (CMV) and lymphocryptovirus (LCV) were found primarily in the context of co-association with each other and adenoviruses. Using viral discovery curves for herpesviruses and adenoviruses, the total viral richness in the sample population of gorillas and chimpanzees was estimated to be a minimum of 23 viruses, corresponding to a detection rate of 83%. These findings represent the first description of DNA viral diversity in feces from free-ranging gorillas and chimpanzees in or near the Odzala-Kokoua National Park and form a basis for understanding the types of viruses circulating among great apes in this region.

Diversity in boron toxicity tolerance of Australian barley (Hordeum vulgare L.) genotypes.

PubMed

Hayes, Julie E; Pallotta, Margaret; Garcia, Melissa; Öz, Mehmet Tufan; Rongala, Jay; Sutton, Tim

2015-09-26

Boron (B) is an important micronutrient for plant growth, but is toxic when levels are too high. This commonly occurs in environments with alkaline soils and relatively low rainfall, including many of the cereal growing regions of southern Australia. Four major genetic loci controlling tolerance to high soil B have been identified in the landrace barley, Sahara 3771. Genes underlying two of the loci encode the B transporters HvBot1 and HvNIP2;1. We investigated sequence and expression level diversity in HvBot1 and HvNIP2;1 across barley germplasm, and identified five novel coding sequence alleles for HvBot1. Lines were identified containing either single or multiple copies of the Sahara HvBot1 allele. We established that only the tandemly duplicated Sahara allele conferred B tolerance, and this duplicated allele was found only in a set of nine lines accessioned in Australian collections as Sahara 3763-3771. HvNIP2;1 coding sequences were highly conserved across barley germplasm. We identified the likely causative SNP in the 5'UTR of Sahara HvNIP2;1, and propose that the creation of a small upstream open reading frame interferes with HvNIP2;1 translation in Sahara 3771. Similar to HvBot1, the tolerant HvNIP2;1 allele was unique to the Sahara barley accessions. We identified a new source of the 2H B tolerance allele controlling leaf symptom development, in the landrace Ethiopia 756. Ethiopia 756, as well as the cultivar Sloop Vic which carries both the 2H and HvBot1 B tolerance alleles derived from Sahara 3771, may be valuable as alternative parents in breeding programs targeted to high soil B environments. There is significant diversity in B toxicity tolerance among contemporary Australian barley varieties but this is not related to variation at any of the four known B tolerance loci, indicating that novel, as yet undiscovered, sources of tolerance exist.

Grain sorghum proteomics: integrated approach toward characterization of endosperm storage proteins in kafirin allelic variants.

PubMed

Cremer, Julia E; Bean, Scott R; Tilley, Michael M; Ioerger, Brian P; Ohm, Jae B; Kaufman, Rhett C; Wilson, Jeff D; Innes, David J; Gilding, Edward K; Godwin, Ian D

2014-10-08

Grain protein composition determines quality traits, such as value for food, feedstock, and biomaterials uses. The major storage proteins in sorghum are the prolamins, known as kafirins. Located primarily on the periphery of the protein bodies surrounding starch, cysteine-rich β- and γ-kafirins may limit enzymatic access to internally positioned α-kafirins and starch. An integrated approach was used to characterize sorghum with allelic variation at the kafirin loci to determine the effects of this genetic diversity on protein expression. Reversed-phase high performance liquid chromatography and lab-on-a-chip analysis showed reductions in alcohol-soluble protein in β-kafirin null lines. Gel-based separation and liquid chromatography-tandem mass spectrometry identified a range of redox active proteins affecting storage protein biochemistry. Thioredoxin, involved in the processing of proteins at germination, has reported impacts on grain digestibility and was differentially expressed across genotypes. Thus, redox states of endosperm proteins, of which kafirins are a subset, could affect quality traits in addition to the expression of proteins.

Automated analysis of high-throughput B-cell sequencing data reveals a high frequency of novel immunoglobulin V gene segment alleles.

PubMed

Gadala-Maria, Daniel; Yaari, Gur; Uduman, Mohamed; Kleinstein, Steven H

2015-02-24

Individual variation in germline and expressed B-cell immunoglobulin (Ig) repertoires has been associated with aging, disease susceptibility, and differential response to infection and vaccination. Repertoire properties can now be studied at large-scale through next-generation sequencing of rearranged Ig genes. Accurate analysis of these repertoire-sequencing (Rep-Seq) data requires identifying the germline variable (V), diversity (D), and joining (J) gene segments used by each Ig sequence. Current V(D)J assignment methods work by aligning sequences to a database of known germline V(D)J segment alleles. However, existing databases are likely to be incomplete and novel polymorphisms are hard to differentiate from the frequent occurrence of somatic hypermutations in Ig sequences. Here we develop a Tool for Ig Genotype Elucidation via Rep-Seq (TIgGER). TIgGER analyzes mutation patterns in Rep-Seq data to identify novel V segment alleles, and also constructs a personalized germline database containing the specific set of alleles carried by a subject. This information is then used to improve the initial V segment assignments from existing tools, like IMGT/HighV-QUEST. The application of TIgGER to Rep-Seq data from seven subjects identified 11 novel V segment alleles, including at least one in every subject examined. These novel alleles constituted 13% of the total number of unique alleles in these subjects, and impacted 3% of V(D)J segment assignments. These results reinforce the highly polymorphic nature of human Ig V genes, and suggest that many novel alleles remain to be discovered. The integration of TIgGER into Rep-Seq processing pipelines will increase the accuracy of V segment assignments, thus improving B-cell repertoire analyses.

The DNA of coral reef biodiversity: predicting and protecting genetic diversity of reef assemblages

PubMed Central

Gaggiotti, Oscar E.; Treml, Eric A.; Wren, Johanna L. K.; Donovan, Mary K.; Toonen, Robert J.

2016-01-01

Conservation of ecological communities requires deepening our understanding of genetic diversity patterns and drivers at community-wide scales. Here, we use seascape genetic analysis of a diversity metric, allelic richness (AR), for 47 reef species sampled across 13 Hawaiian Islands to empirically demonstrate that large reefs high in coral cover harbour the greatest genetic diversity on average. We found that a species's life history (e.g. depth range and herbivory) mediates response of genetic diversity to seascape drivers in logical ways. Furthermore, a metric of combined multi-species AR showed strong coupling to species richness and habitat area, quality and stability that few species showed individually. We hypothesize that macro-ecological forces and species interactions, by mediating species turnover and occupancy (and thus a site's mean effective population size), influence the aggregate genetic diversity of a site, potentially allowing it to behave as an apparent emergent trait that is shaped by the dominant seascape drivers. The results highlight inherent feedbacks between ecology and genetics, raise concern that genetic resilience of entire reef communities is compromised by factors that reduce coral cover or available habitat, including thermal stress, and provide a foundation for new strategies for monitoring and preserving biodiversity of entire reef ecosystems. PMID:27122569

The DNA of coral reef biodiversity: predicting and protecting genetic diversity of reef assemblages.

PubMed

Selkoe, Kimberly A; Gaggiotti, Oscar E; Treml, Eric A; Wren, Johanna L K; Donovan, Mary K; Toonen, Robert J

2016-04-27

Conservation of ecological communities requires deepening our understanding of genetic diversity patterns and drivers at community-wide scales. Here, we use seascape genetic analysis of a diversity metric, allelic richness (AR), for 47 reef species sampled across 13 Hawaiian Islands to empirically demonstrate that large reefs high in coral cover harbour the greatest genetic diversity on average. We found that a species's life history (e.g. depth range and herbivory) mediates response of genetic diversity to seascape drivers in logical ways. Furthermore, a metric of combined multi-species AR showed strong coupling to species richness and habitat area, quality and stability that few species showed individually. We hypothesize that macro-ecological forces and species interactions, by mediating species turnover and occupancy (and thus a site's mean effective population size), influence the aggregate genetic diversity of a site, potentially allowing it to behave as an apparent emergent trait that is shaped by the dominant seascape drivers. The results highlight inherent feedbacks between ecology and genetics, raise concern that genetic resilience of entire reef communities is compromised by factors that reduce coral cover or available habitat, including thermal stress, and provide a foundation for new strategies for monitoring and preserving biodiversity of entire reef ecosystems. © 2016 The Authors.

Long-range high-speed visible light communication system over 100-m outdoor transmission utilizing receiver diversity technology

NASA Astrophysics Data System (ADS)

Wang, Yiguang; Huang, Xingxing; Shi, Jianyang; Wang, Yuan-quan; Chi, Nan

2016-05-01

Visible light communication (VLC) has no doubt become a promising candidate for future wireless communications due to the increasing trends in the usage of light-emitting diodes (LEDs). In addition to indoor high-speed wireless access and positioning applications, VLC usage in outdoor scenarios, such as vehicle networks and intelligent transportation systems, are also attracting significant interest. However, the complex outdoor environment and ambient noise are the key challenges for long-range high-speed VLC outdoor applications. To improve system performance and transmission distance, we propose to use receiver diversity technology in an outdoor VLC system. Maximal ratio combining-based receiver diversity technology is utilized in two receivers to achieve the maximal signal-to-noise ratio. A 400-Mb/s VLC transmission using a phosphor-based white LED and a 1-Gb/s wavelength division multiplexing VLC transmission using a red-green-blue LED are both successfully achieved over a 100-m outdoor distance with the bit error rate below the 7% forward error correction limit of 3.8×10-3. To the best of our knowledge, this is the highest data rate at 100-m outdoor VLC transmission ever achieved. The experimental results clearly prove the benefit and feasibility of receiver diversity technology for long-range high-speed outdoor VLC systems.

Uneven segregation of sporophytic self-incompatibility alleles in Arabidopsis lyrata.

PubMed

Bechsgaard, J; Bataillon, T; Schierup, M H

2004-05-01

Self-incompatibility in Arabidopsis lyrata is sporophytically controlled by the multi-allelic S-locus. Self-incompatibility alleles (S-alleles) are under strong negative frequency dependent selection because pollen carrying common S-alleles have fewer mating opportunities. Population genetics theory predicts that deleterious alleles can accumulate if linked to the S-locus. This was tested by studying segregation of S-alleles in 11 large full sib families in A. lyrata. Significant segregation distortion leading to an up to fourfold difference in transmission rates was found in six families. Differences in transmission rates were not significantly different in reciprocal crosses and the distortions observed were compatible with selection acting at the gametic stage alone. The S-allele with the largest segregation advantage is also the most recessive, and is very common in natural populations concordant with its apparent segregation advantage. These results imply that frequencies of S-alleles in populations of A. lyrata cannot be predicted based on simple models of frequency-dependent selection alone.

The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model

PubMed Central

Fields, Peter D.; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

2017-01-01

Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis

The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model.

PubMed

Bento, Gilberto; Routtu, Jarkko; Fields, Peter D; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

2017-02-01

Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis.

Allelic variants of hereditary prions: The bimodularity principle.

PubMed

Tikhodeyev, Oleg N; Tarasov, Oleg V; Bondarev, Stanislav A

2017-01-02

Modern biology requires modern genetic concepts equally valid for all discovered mechanisms of inheritance, either "canonical" (mediated by DNA sequences) or epigenetic. Applying basic genetic terms such as "gene" and "allele" to protein hereditary factors is one of the necessary steps toward these concepts. The basic idea that different variants of the same prion protein can be considered as alleles has been previously proposed by Chernoff and Tuite. In this paper, the notion of prion allele is further developed. We propose the idea that any prion allele is a bimodular hereditary system that depends on a certain DNA sequence (DNA determinant) and a certain epigenetic mark (epigenetic determinant). Alteration of any of these 2 determinants may lead to establishment of a new prion allele. The bimodularity principle is valid not only for hereditary prions; it seems to be universal for any epigenetic hereditary factor.

A genomic scale map of genetic diversity in Trypanosoma cruzi

PubMed Central

2012-01-01

Background Trypanosoma cruzi, the causal agent of Chagas Disease, affects more than 16 million people in Latin America. The clinical outcome of the disease results from a complex interplay between environmental factors and the genetic background of both the human host and the parasite. However, knowledge of the genetic diversity of the parasite, is currently limited to a number of highly studied loci. The availability of a number of genomes from different evolutionary lineages of T. cruzi provides an unprecedented opportunity to look at the genetic diversity of the parasite at a genomic scale. Results Using a bioinformatic strategy, we have clustered T. cruzi sequence data available in the public domain and obtained multiple sequence alignments in which one or two alleles from the reference CL-Brener were included. These data covers 4 major evolutionary lineages (DTUs): TcI, TcII, TcIII, and the hybrid TcVI. Using these set of alignments we have identified 288,957 high quality single nucleotide polymorphisms and 1,480 indels. In a reduced re-sequencing study we were able to validate ~ 97% of high-quality SNPs identified in 47 loci. Analysis of how these changes affect encoded protein products showed a 0.77 ratio of synonymous to non-synonymous changes in the T. cruzi genome. We observed 113 changes that introduce or remove a stop codon, some causing significant functional changes, and a number of tri-allelic and tetra-allelic SNPs that could be exploited in strain typing assays. Based on an analysis of the observed nucleotide diversity we show that the T. cruzi genome contains a core set of genes that are under apparent purifying selection. Interestingly, orthologs of known druggable targets show statistically significant lower nucleotide diversity values. Conclusions This study provides the first look at the genetic diversity of T. cruzi at a genomic scale. The analysis covers an estimated ~ 60% of the genetic diversity present in the population, providing an

Genetic diversity among sea otter isolates of Toxoplasma gondii

USGS Publications Warehouse

Sundar, N.; Cole, Rebecca A.; Thomas, N.J.; Majumdar, D.; Dubey, J.P.; Su, C.

2008-01-01

Sea otters (Enhydra lutris) have been reported to become infected with Toxoplasma gondiiand at times succumb to clinical disease. Here, we determined genotypes of 39 T. gondiiisolates from 37 sea otters in two geographically distant locations (25 from California and 12 from Washington). Six genotypes were identified using 10 PCR-RFLP genetic markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico, and by DNA sequencing of loci SAG1 and GRA6 in 13 isolates. Of these 39 isolates, 13 (33%) were clonal Type II which can be further divided into two groups at the locus Apico. Two of the 39 isolates had Type II alleles at all loci except a Type I allele at locus L358. One isolate had Type II alleles at all loci except the Type I alleles at loci L358 and Apico. One isolate had Type III alleles at all loci except Type II alleles at SAG2 and Apico. Two sea otter isolates had a mixed infection. Twenty-one (54%) isolates had an unique allele at SAG1 locus. Further genotyping or DNA sequence analysis for 18 of these 21 isolates at loci SAG1 and GRA6 revealed that there were two different genotypes, including the previously identified Type X (four isolates) and a new genotype named Type A (14 isolates). The results from this study suggest that the sea otter isolates are genetically diverse.

Identifying Darwinian Selection Acting on Different Human APOL1 Variants among Diverse African Populations

PubMed Central

Ko, Wen-Ya; Rajan, Prianka; Gomez, Felicia; Scheinfeldt, Laura; An, Ping; Winkler, Cheryl A.; Froment, Alain; Nyambo, Thomas B.; Omar, Sabah A.; Wambebe, Charles; Ranciaro, Alessia; Hirbo, Jibril B.; Tishkoff, Sarah A.

2013-01-01

Disease susceptibility can arise as a consequence of adaptation to infectious disease. Recent findings have suggested that higher rates of chronic kidney disease (CKD) in individuals with recent African ancestry might be attributed to two risk alleles (G1 and G2) at the serum-resistance-associated (SRA)-interacting-domain-encoding region of APOL1. These two alleles appear to have arisen adaptively, possibly as a result of their protective effects against human African trypanosomiasis (HAT), or African sleeping sickness. In order to explore the distribution of potential functional variation at APOL1, we studied nucleotide variation in 187 individuals across ten geographically and genetically diverse African ethnic groups with exposure to two Trypanosoma brucei subspecies that cause HAT. We observed unusually high levels of nonsynonymous polymorphism in the regions encoding the functional domains that are required for lysing parasites. Whereas allele frequencies of G2 were similar across all populations (3%–8%), the G1 allele was only common in the Yoruba (39%). Additionally, we identified a haplotype (termed G3) that contains a nonsynonymous change at the membrane-addressing-domain-encoding region of APOL1 and is present in all populations except for the Yoruba. Analyses of long-range patterns of linkage disequilibrium indicate evidence of recent selection acting on the G3 haplotype in Fulani from Cameroon. Our results indicate that the G1 and G2 variants in APOL1 are geographically restricted and that there might be other functional variants that could play a role in HAT resistance and CKD risk in African populations. PMID:23768513

Molecular diversity and population structure at the Cytochrome P450 3A5 gene in Africa

PubMed Central

2013-01-01

Background Cytochrome P450 3A5 (CYP3A5) is an enzyme involved in the metabolism of many therapeutic drugs. CYP3A5 expression levels vary between individuals and populations, and this contributes to adverse clinical outcomes. Variable expression is largely attributed to four alleles, CYP3A5*1 (expresser allele); CYP3A5*3 (rs776746), CYP3A5*6 (rs10264272) and CYP3A5*7 (rs41303343) (low/non-expresser alleles). Little is known about CYP3A5 variability in Africa, a region with considerable genetic diversity. Here we used a multi-disciplinary approach to characterize CYP3A5 variation in geographically and ethnically diverse populations from in and around Africa, and infer the evolutionary processes that have shaped patterns of diversity in this gene. We genotyped 2538 individuals from 36 diverse populations in and around Africa for common low/non-expresser CYP3A5 alleles, and re-sequenced the CYP3A5 gene in five Ethiopian ethnic groups. We estimated the ages of low/non-expresser CYP3A5 alleles using a linked microsatellite and assuming a step-wise mutation model of evolution. Finally, we examined a hypothesis that CYP3A5 is important in salt retention adaptation by performing correlations with ecological data relating to aridity for the present day, 10,000 and 50,000 years ago. Results We estimate that ~43% of individuals within our African dataset express CYP3A5, which is lower than previous independent estimates for the region. We found significant intra-African variability in CYP3A5 expression phenotypes. Within Africa the highest frequencies of high-activity alleles were observed in equatorial and Niger-Congo speaking populations. Ethiopian allele frequencies were intermediate between those of other sub-Saharan African and non-African groups. Re-sequencing of CYP3A5 identified few additional variants likely to affect CYP3A5 expression. We estimate the ages of CYP3A5*3 as ~76,400 years and CYP3A5*6 as ~218,400 years. Finally we report that global CYP3A5 expression

Habitat predictors of genetic diversity for two sympatric wetland-breeding amphibian species.

PubMed

McKee, Anna M; Maerz, John C; Smith, Lora L; Glenn, Travis C

2017-08-01

Population genetic diversity is widely accepted as important to the conservation and management of wildlife. However, habitat features may differentially affect evolutionary processes that facilitate population genetic diversity among sympatric species. We measured genetic diversity for two pond-breeding amphibian species (Dwarf salamanders, Eurycea quadridigitata ; and Southern Leopard frogs, Lithobates sphenocephalus ) to understand how habitat characteristics and spatial scale affect genetic diversity across a landscape. Samples were collected from wetlands on a longleaf pine reserve in Georgia. We genotyped microsatellite loci for both species to assess population structures and determine which habitat features were most closely associated with observed heterozygosity and rarefied allelic richness. Both species exhibited significant population genetic structure; however, structure in Southern Leopard frogs was driven primarily by one outlier site. Dwarf salamander allelic richness was greater at sites with less surrounding road area within 0.5 km and more wetland area within 1.0 and 2.5 km, and heterozygosity was greater at sites with more wetland area within 0.5 km. In contrast, neither measure of Southern Leopard frog genetic diversity was associated with any habitat features at any scale we evaluated. Genetic diversity in the Dwarf salamander was strongly associated with land cover variables up to 2.5 km away from breeding wetlands, and/or results suggest that minimizing roads in wetland buffers may be beneficial to the maintenance of population genetic diversity. This study suggests that patterns of genetic differentiation and genetic diversity have associations with different habitat features across different spatial scales for two syntopic pond-breeding amphibian species.

Diversity of seM in Streptococcus equi subsp. equi isolated from strangles outbreaks.

PubMed

Libardoni, Felipe; Vielmo, Andréia; Farias, Luana; Matter, Letícia Beatriz; Pötter, Luciana; Spilki, Fernando Rosado; de Vargas, Agueda Castagna

2013-03-23

Strangles is the main upper respiratory tract disease of horses. There are currently no studies on the changes in alleles of the M protein gene (seM) in Brazilian isolates of Streptococcus equi ssp. equi (S. equi). This study aimed to analyze and differentiate molecularly S. equi isolates from equine clinical specimens from southern Brazil, between 1994 and 2010. seM alleles were analyzed in 47 isolates of S. equi obtained from clinical cases of strangles (15 Thoroughbred horses, 29 Crioulo breed horses and three Brasileiro de Hipismo--BH). seM alleles characterization was performed by comparing variable region sequences of the seM gene. The alleles were also phylogenetically grouped by Neighbor-joining analysis, which demonstrated the geographic distribution of those in properties from southern Brazil. Fifteen alleles of the gene seM were found among the 47 S. equi isolates analyzed. Among these, only one allele (seM-61), which was identified in seven isolates (14.9%), was found in the database PubMLST-seM. Within the new alleles, allele seM-115 was the most prevalent, having been found in 13 isolates (27.7%), followed by allele seM-117 in 10 isolates (21.3%). In the Brazilian horse population studied, there is greater diversity of M protein alleles in S. equi isolates compared to worldwide data deposited in PubMLST-seM. Among the 15 seM alleles identified, only one allele sequence was previously published. The alleles identification is important to control the disease by guiding selection of strains for the manufacture of commercial and autogenous vaccines. Copyright © 2012 Elsevier B.V. All rights reserved.

Genetic Adaptation to Climate in White Spruce Involves Small to Moderate Allele Frequency Shifts in Functionally Diverse Genes.

PubMed

Hornoy, Benjamin; Pavy, Nathalie; Gérardi, Sébastien; Beaulieu, Jean; Bousquet, Jean

2015-11-11

Understanding the genetic basis of adaptation to climate is of paramount importance for preserving and managing genetic diversity in plants in a context of climate change. Yet, this objective has been addressed mainly in short-lived model species. Thus, expanding knowledge to nonmodel species with contrasting life histories, such as forest trees, appears necessary. To uncover the genetic basis of adaptation to climate in the widely distributed boreal conifer white spruce (Picea glauca), an environmental association study was conducted using 11,085 single nucleotide polymorphisms representing 7,819 genes, that is, approximately a quarter of the transcriptome.Linear and quadratic regressions controlling for isolation-by-distance, and the Random Forest algorithm, identified several dozen genes putatively under selection, among which 43 showed strongest signals along temperature and precipitation gradients. Most of them were related to temperature. Small to moderate shifts in allele frequencies were observed. Genes involved encompassed a wide variety of functions and processes, some of them being likely important for plant survival under biotic and abiotic environmental stresses according to expression data. Literature mining and sequence comparison also highlighted conserved sequences and functions with angiosperm homologs.Our results are consistent with theoretical predictions that local adaptation involves genes with small frequency shifts when selection is recent and gene flow among populations is high. Accordingly, genetic adaptation to climate in P. glauca appears to be complex, involving many independent and interacting gene functions, biochemical pathways, and processes. From an applied perspective, these results shall lead to specific functional/association studies in conifers and to the development of markers useful for the conservation of genetic resources. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular

Geographic distribution of genetic diversity in populations of Rio Grande Chub Gila pandora

USGS Publications Warehouse

Galindo, Rene; Wilson, Wade; Caldwell, Colleen A.

2016-01-01

In the southwestern United States (US), the Rio Grande chub (Gila pandora) is state-listed as a fish species of greatest conservation need and federally listed as sensitive due to habitat alterations and competition with non-native fishes. Characterizing genetic diversity, genetic population structure, and effective number of breeders will assist with conservation efforts by providing a baseline of genetic metrics. Genetic relatedness within and among G. pandora populations throughout New Mexico was characterized using 11 microsatellite loci among 15 populations in three drainage basins (Rio Grande, Pecos, Canadian). Observed heterozygosity (HO) ranged from 0.71–0.87 and was similar to expected heterozygosity (0.75–0.87). Rio Ojo Caliente (Rio Grande) had the highest allelic richness (AR = 15.09), while Upper Rio Bonito (Pecos) had the lowest allelic richness (AR = 6.75). Genetic differentiation existed among all populations with the lowest genetic variation occurring within the Pecos drainage. STRUCTURE analysis revealed seven genetic clusters. Populations of G. pandora within the upper Rio Grande drainage (Rio Ojo Caliente, Rio Vallecitos, Rio Pueblo de Taos) had high levels of admixture with Q-values ranging from 0.30–0.50. In contrast, populations within the Pecos drainage (Pecos River and Upper Rio Bonito) had low levels of admixture (Q = 0.94 and 0.87, respectively). Estimates of effective number of breeders (N b ) varied from 6.1 (Pecos: Upper Rio Bonito) to 109.7 (Rio Grande: Rio Peñasco) indicating that populations in the Pecos drainage are at risk of extirpation. In the event that management actions are deemed necessary to preserve or increase genetic diversity of G. pandora, consideration must be given as to which populations are selected for translocation.

Genetic diversity and population structure in Physalis peruviana and related taxa based on InDels and SNPs derived from COSII and IRG markers

PubMed Central

Garzón-Martínez, Gina A.; Osorio-Guarín, Jaime A.; Delgadillo-Durán, Paola; Mayorga, Franklin; Enciso-Rodríguez, Felix E.; Landsman, David

2015-01-01

The genus Physalis is common in the Americas and includes several economically important species, among them Physalis peruviana that produces appetizing edible fruits. We studied the genetic diversity and population structure of P. peruviana and characterized 47 accessions of this species along with 13 accessions of related taxa consisting of 222 individuals from the Colombian Corporation of Agricultural Research (CORPOICA) germplasm collection, using Conserved Orthologous Sequences (COSII) and Immunity Related Genes (IRGs). In addition, 642 Single Nucleotide Polymorphism (SNPs) markers were identified and used for the genetic diversity analysis. A total of 121 alleles were detected in 24 InDels loci ranging from 2 to 9 alleles per locus, with an average of 5.04 alleles per locus. The average number of alleles in the SNP markers was two. The observed heterozygosity for P. peruviana with InDel and SNP markers was higher (0.48 and 0.59) than the expected heterozygosity (0.30 and 0.41). Interestingly, the observed heterozygosity in related taxa (0.4 and 0.12) was lower than the expected heterozygosity (0.59 and 0.25). The coefficient of population differentiation FST was 0.143 (InDels) and 0.038 (SNPs), showing a relatively low level of genetic differentiation among P. peruviana and related taxa. Higher levels of genetic variation were instead observed within populations based on the AMOVA analysis. Population structure analysis supported the presence of two main groups and PCA analysis based on SNP markers revealed two distinct clusters in the P. peruviana accessions corresponding to their state of cultivation. In this study, we identified molecular markers useful to detect genetic variation in Physalis germplasm for assisting conservation and crossbreeding strategies. PMID:26550601

Genetic diversity and population structure in Physalis peruviana and related taxa based on InDels and SNPs derived from COSII and IRG markers.

PubMed

Garzón-Martínez, Gina A; Osorio-Guarín, Jaime A; Delgadillo-Durán, Paola; Mayorga, Franklin; Enciso-Rodríguez, Felix E; Landsman, David; Mariño-Ramírez, Leonardo; Barrero, Luz Stella

2015-12-01

The genus Physalis is common in the Americas and includes several economically important species, among them Physalis peruviana that produces appetizing edible fruits. We studied the genetic diversity and population structure of P. peruviana and characterized 47 accessions of this species along with 13 accessions of related taxa consisting of 222 individuals from the Colombian Corporation of Agricultural Research (CORPOICA) germplasm collection, using Conserved Orthologous Sequences (COSII) and Immunity Related Genes (IRGs). In addition, 642 Single Nucleotide Polymorphism (SNPs) markers were identified and used for the genetic diversity analysis. A total of 121 alleles were detected in 24 InDels loci ranging from 2 to 9 alleles per locus, with an average of 5.04 alleles per locus. The average number of alleles in the SNP markers was two. The observed heterozygosity for P. peruviana with InDel and SNP markers was higher (0.48 and 0.59) than the expected heterozygosity (0.30 and 0.41). Interestingly, the observed heterozygosity in related taxa (0.4 and 0.12) was lower than the expected heterozygosity (0.59 and 0.25). The coefficient of population differentiation F ST was 0.143 (InDels) and 0.038 (SNPs), showing a relatively low level of genetic differentiation among P. peruviana and related taxa. Higher levels of genetic variation were instead observed within populations based on the AMOVA analysis. Population structure analysis supported the presence of two main groups and PCA analysis based on SNP markers revealed two distinct clusters in the P. peruviana accessions corresponding to their state of cultivation. In this study, we identified molecular markers useful to detect genetic variation in Physalis germplasm for assisting conservation and crossbreeding strategies.

India Allele Finder: a web-based annotation tool for identifying common alleles in next-generation sequencing data of Indian origin.

PubMed

Zhang, Jimmy F; James, Francis; Shukla, Anju; Girisha, Katta M; Paciorkowski, Alex R

2017-06-27

We built India Allele Finder, an online searchable database and command line tool, that gives researchers access to variant frequencies of Indian Telugu individuals, using publicly available fastq data from the 1000 Genomes Project. Access to appropriate population-based genomic variant annotation can accelerate the interpretation of genomic sequencing data. In particular, exome analysis of individuals of Indian descent will identify population variants not reflected in European exomes, complicating genomic analysis for such individuals. India Allele Finder offers improved ease-of-use to investigators seeking to identify and annotate sequencing data from Indian populations. We describe the use of India Allele Finder to identify common population variants in a disease quartet whole exome dataset, reducing the number of candidate single nucleotide variants from 84 to 7. India Allele Finder is freely available to investigators to annotate genomic sequencing data from Indian populations. Use of India Allele Finder allows efficient identification of population variants in genomic sequencing data, and is an example of a population-specific annotation tool that simplifies analysis and encourages international collaboration in genomics research.

Patterns of Adaptive and Neutral Diversity Identify the Xiaoxiangling Mountains as a Refuge for the Giant Panda

PubMed Central

Wan, Qiu-Hong; Lou, Ji-Kang; Li, Wen-Jing; Ge, Yun-Fa; Fang, Sheng-Guo

2013-01-01

Genetic variation plays a significant role in maintaining the evolutionary potential of a species. Comparing the patterns of adaptive and neutral diversity in extant populations is useful for understanding the local adaptations of a species. In this study, we determined the fine-scale genetic structure of 6 extant populations of the giant panda (Ailuropoda melanoleuca) using mtDNA and DNA fingerprints, and then overlaid adaptive variations in 6 functional Aime-MHC class II genes (DRA, DRB3, DQA1, DQA2, DQB1, and DQB2) on this framework. We found that: (1) analysis of the mtDNA and DNA fingerprint-based networks of the 6 populations identified the independent evolutionary histories of the 2 panda subspecies; (2) the basal (ancestral) branches of the fingerprint-based Sichuan-derived network all originated from the smallest Xiaoxiangling (XXL) population, suggesting the status of a glacial refuge in XXL; (3) the MHC variations among the tested populations showed that the XXL population exhibited extraordinary high levels of MHC diversity in allelic richness, which is consistent with the diversity characteristics of a glacial refuge; (4) the phylogenetic tree showed that the basal clades of giant panda DQB sequences were all occupied by XXL-specific sequences, providing evidence for the ancestor-resembling traits of XXL. Finally, we found that the giant panda had many more DQ alleles than DR alleles (33∶13), contrary to other mammals, and that the XXL refuge showed special characteristics in the DQB loci, with 7 DQB members of 9 XXL-unique alleles. Thus, this study identified XXL as a glacial refuge, specifically harboring the most number of primitive DQB alleles. PMID:23894623

Patterns of adaptive and neutral diversity identify the Xiaoxiangling mountains as a refuge for the giant panda.

PubMed

Chen, Yi-Yan; Zhu, Ying; Wan, Qiu-Hong; Lou, Ji-Kang; Li, Wen-Jing; Ge, Yun-Fa; Fang, Sheng-Guo

2013-01-01

Genetic variation plays a significant role in maintaining the evolutionary potential of a species. Comparing the patterns of adaptive and neutral diversity in extant populations is useful for understanding the local adaptations of a species. In this study, we determined the fine-scale genetic structure of 6 extant populations of the giant panda (Ailuropoda melanoleuca) using mtDNA and DNA fingerprints, and then overlaid adaptive variations in 6 functional Aime-MHC class II genes (DRA, DRB3, DQA1, DQA2, DQB1, and DQB2) on this framework. We found that: (1) analysis of the mtDNA and DNA fingerprint-based networks of the 6 populations identified the independent evolutionary histories of the 2 panda subspecies; (2) the basal (ancestral) branches of the fingerprint-based Sichuan-derived network all originated from the smallest Xiaoxiangling (XXL) population, suggesting the status of a glacial refuge in XXL; (3) the MHC variations among the tested populations showed that the XXL population exhibited extraordinary high levels of MHC diversity in allelic richness, which is consistent with the diversity characteristics of a glacial refuge; (4) the phylogenetic tree showed that the basal clades of giant panda DQB sequences were all occupied by XXL-specific sequences, providing evidence for the ancestor-resembling traits of XXL. Finally, we found that the giant panda had many more DQ alleles than DR alleles (33∶13), contrary to other mammals, and that the XXL refuge showed special characteristics in the DQB loci, with 7 DQB members of 9 XXL-unique alleles. Thus, this study identified XXL as a glacial refuge, specifically harboring the most number of primitive DQB alleles.

Allelic Expression of Deleterious Protein-Coding Variants across Human Tissues

PubMed Central

Kukurba, Kimberly R.; Zhang, Rui; Li, Xin; Smith, Kevin S.; Knowles, David A.; How Tan, Meng; Piskol, Robert; Lek, Monkol; Snyder, Michael; MacArthur, Daniel G.; Li, Jin Billy; Montgomery, Stephen B.

2014-01-01

Personal exome and genome sequencing provides access to loss-of-function and rare deleterious alleles whose interpretation is expected to provide insight into individual disease burden. However, for each allele, accurate interpretation of its effect will depend on both its penetrance and the trait's expressivity. In this regard, an important factor that can modify the effect of a pathogenic coding allele is its level of expression; a factor which itself characteristically changes across tissues. To better inform the degree to which pathogenic alleles can be modified by expression level across multiple tissues, we have conducted exome, RNA and deep, targeted allele-specific expression (ASE) sequencing in ten tissues obtained from a single individual. By combining such data, we report the impact of rare and common loss-of-function variants on allelic expression exposing stronger allelic bias for rare stop-gain variants and informing the extent to which rare deleterious coding alleles are consistently expressed across tissues. This study demonstrates the potential importance of transcriptome data to the interpretation of pathogenic protein-coding variants. PMID:24786518

Characterization of the treefrog null allele, 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guttman, S.I.

1992-04-01

Spring peeper (Hyla crucifer) tadpoles collected from the waste storage area during the Biological and Ecological Site Characterization of the Feed Materials Production Center (FEMP) in 1986 and 1987 appeared to be unique. A null (inactive) allele was found at the glucose phosphate isomerase enzyme locus in significant frequencies (approximately 20%) each year; this allele did not appear to occur in the offsite sample collected approximately 15km from the FEMP. Null alleles at this locus have not been reported in other amphibian populations; when they have been found in other organisms they have invariably been lethal in the homozygous condition.

Genetic diversity and population differentiation of small giant clam Tridacna maxima in Comoros islands assessed by microsatellite markers.

PubMed

Ahmed Mohamed, Nadjim; Yu, Qian; Chanfi, Mohamed Ibrahim; Li, Yangping; Wang, Shi; Huang, Xiaoting; Bao, Zhenmin

2016-01-01

Small giant clam, Tridacna maxima , widely distributed from French Polynesia to East Africa, has faced population declines due to over-exploitation. Comoros islands are an important biogeographic region due to potential richness of marine species, but no relevant information is available. In order to facilitate devising effective conservation management plan for T. maxima , nine microsatellite markers were used to survey genetic diversity and population differentiation of 72 specimens collected from three Comoros islands, Grande Comore, Moheli and Anjouan. A total of 51 alleles were detected ranged from 2 to 8 per locus. Observed and expected heterozygosity varied from 0.260 to 0.790 and from 0.542 to 0.830, respectively. All populations have high genetic diversity, especially the population in Moheli, a protected area, has higher genetic diversity than the others. Significant heterozygote deficiencies were recorded, and null alleles were probably the main factor leading to these deficits. F ST value indicated medium genetic differentiation among the populations. Although significant, AMOVA revealed 48.9 % of genetic variation within individuals and only a small variation of 8.9 % was found between populations. Gene flow was high ( Nm  = 12.40) between Grande Comore and Moheli, while lower ( Nm  = 1.80) between Grande Comore and Anjouan, explaining geographic barriers to genetic exchanges might exist in these two islands. Global gene flow analysis ( Nm  = 5.50) showed that larval dispersal is enough to move between the islands. The high genetic diversity and medium population differentiation revealed in the present study offer useful information on genetic conservation of small giant clams.

Diversity of Sarcocystis spp shed by opossums in Brazil inferred with phylogenetic analysis of DNA coding ITS1, cytochrome B, and surface antigens.

PubMed

Valadas, Samantha Y O B; da Silva, Juliana I G; Lopes, Estela Gallucci; Keid, Lara B; Zwarg, Ticiana; de Oliveira, Alice S; Sanches, Thaís C; Joppert, Adriana M; Pena, Hilda F J; Oliveira, Tricia M F S; Ferreira, Helena L; Soares, Rodrigo M

2016-05-01

Although few species of Sarcocystis are known to use marsupials of the genus Didelphis as definitive host, an extensive diversity of alleles of surface antigen genes (sag2, sag3, and sag4) has been described in samples of didelphid opossums in Brazil. In this work, we studied 25 samples of Sarcocystis derived from gastrointestinal tract of opossums of the genus Didelphis by accessing the variability of sag2, sag3, sag4, gene encoding cytochrome b (cytB) and first internal transcribed spacer (ITS1). Reference samples of Sarcocystis neurona (SN138) and Sarcocystis falcatula (SF1) maintained in cell culture were also analyzed. We found four allele variants of cytB, seven allele variants of ITS1, 10 allele variants of sag2, 13 allele variants of sag3, and 6 allele variants of sag4. None of the sporocyst-derived sequences obtained from Brazilian opossums revealed 100% identity to SN138 at cytB gene, nor to SN138 or SF1 at ITS1 locus. In addition, none of the sag alleles were found identical to either SF1 or SN138 homologous sequences, and a high number of new sag allele types were found other than those previously described in Brazil. Out of ten sag2 alleles, four are novel, while eight out of 13 sag3 alleles are novel and one out of six sag4 alleles is novel. Further studies are needed to clarify if such a vast repertoire of allele variants of Sarcocystis is the consequence of re-assortments driven by sexual exchange, in order to form individuals with highly diverse characteristics, such as pathogenicity, host spectrum, among others or if it only represents allele variants of different species with different biological traits. Copyright © 2016 Elsevier Inc. All rights reserved.

Isolation and characterization of 108 novel microsatellite loci for Atlantic coastal killifish (Fundulus heteroclitus)

EPA Science Inventory

We characterized 108 polymorphic microsatellite loci for the mummichog (Fundulus heteroclitus), an Atlantic coastal killifish. Allelic diversity among 26 individuals ranged between 2 and 15 alleles per locus, while expected heterozygosity ranged from 0.075 to 0.904. Significant ...

Competition-based cellular peptide binding assays for 13 prevalent HLA class I alleles using fluorescein-labeled synthetic peptides.

PubMed

Kessler, Jan H; Mommaas, Bregje; Mutis, Tuna; Huijbers, Ivo; Vissers, Debby; Benckhuijsen, Willemien E; Schreuder, Geziena M Th; Offringa, Rienk; Goulmy, Els; Melief, Cornelis J M; van der Burg, Sjoerd H; Drijfhout, Jan W

2003-02-01

We report the development, validation, and application of competition-based peptide binding assays for 13 prevalent human leukocyte antigen (HLA) class I alleles. The assays are based on peptide binding to HLA molecules on living cells carrying the particular allele. Competition for binding between the test peptide of interest and a fluorescein-labeled HLA class I binding peptide is used as read out. The use of cell membrane-bound HLA class I molecules circumvents the need for laborious biochemical purification of these molecules in soluble form. Previously, we have applied this principle for HLA-A2 and HLA-A3. We now describe the assays for HLA-A1, HLA-A11, HLA-A24, HLA-A68, HLA-B7, HLA-B8, HLA-B14, HLA-B35, HLA-B60, HLA-B61, and HLA-B62. Together with HLA-A2 and HLA-A3, these alleles cover more than 95% of the Caucasian population. Several allele-specific parameters were determined for each assay. Using these assays, we identified novel HLA class I high-affinity binding peptides from HIVpol, p53, PRAME, and minor histocompatibility antigen HA-1. Thus these convenient and accurate peptide-binding assays will be useful for the identification of putative cytotoxic T lymphocyte epitopes presented on a diverse array of HLA class I molecules.

Genetic structure and diversity of coffee (Coffea) across Africa and the Indian Ocean islands revealed using microsatellites

PubMed Central

Razafinarivo, Norosoa J.; Guyot, Romain; Davis, Aaron P.; Couturon, Emmanuel; Hamon, Serge; Crouzillat, Dominique; Rigoreau, Michel; Dubreuil-Tranchant, Christine; Poncet, Valerie; De Kochko, Alexandre; Rakotomalala, Jean-Jacques; Hamon, Perla

2013-01-01

Background and Aims The coffee genus (Coffea) comprises 124 species, and is indigenous to the Old World Tropics. Due to its immense economic importance, Coffea has been the focus of numerous genetic diversity studies, but despite this effort it remains insufficiently studied. In this study the genetic diversity and genetic structure of Coffea across Africa and the Indian Ocean islands is investigated. Methods Genetic data were produced using 13 polymorphic nuclear microsatellite markers (simple sequence repeats, SSRs), including seven expressed sequence tag-SSRs, and the data were analysed using model- and non-model-based methods. The study includes a total of 728 individuals from 60 species. Key Results Across Africa and the Indian Ocean islands Coffea comprises a closely related group of species with an overall pattern of genotypes running from west to east. Genetic structure was identified in accordance with pre-determined geographical regions and phylogenetic groups. There is a good relationship between morpho-taxonomic species delimitations and genetic units. Genetic diversity in African and Indian Ocean Coffea is high in terms of number of alleles detected, and Madagascar appears to represent a place of significant diversification in terms of allelic richness and species diversity. Conclusions Cross-species SSR transferability in African and Indian Ocean islands Coffea was very efficient. On the basis of the number of private alleles, diversification in East Africa and the Indian Ocean islands appears to be more recent than in West and West-Central Africa, although this general trend is complicated in Africa by the position of species belonging to lineages connecting the main geographical regions. The general pattern of phylogeography is not in agreement with an overall east to west (Mascarene, Madagascar, East Africa, West Africa) increase in genome size, the high proportion of shared alleles between the four regions or the high numbers of exclusive shared

Apolipoprotein E alleles in Alzheimer`s and Parkinson`s patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poduslo, S.E.; Schwankhaus, J.D.

1994-09-01

A number of investigators have found an association between the apolipoprotein E4 allele and Alzheimer`s disease. The E4 allele appears at a higher frequency in late onset familial Alzheimer`s patients. In our studies we obtained blood samples from early and late onset familial and sporadic Alzheimer`s patients and spouses, as well as from Parkinson`s patients. The patients were diagnosed as probable Alzheimer`s patients after a neurological examination, extensive blood work, and a CAT scan. The diagnosis was made according to the NINCDS-ADRDA criteria. The apolipoprotein E4 polymorphism was detected after PCR amplification of genomic DNA, restriction enzyme digestion with Hhal,more » and polyacrylamide gel electrophoresis. Ethidium bromide-stained bands at 91 bp were designated as allele 3, at 83 bp as allele 2, and at 72 bp as allele 4. Of the 84 probable Alzheimer`s patients (all of whom were Caucasian), 47 were heterozygous and 13 were homozygous for the E4 allele. There were 26 early onset patients; 13 were heterozygous and 7 homozygous for the E4 allele. The frequencies for the E4 allele for late onset familial patients was 0.45 and for sporadic patients was 0.37. We analyzed 77 spouses with an average age of 71.9 {plus_minus} 7.4 years as controls, and 15 were heterozygous for the E4 allele for an E4 frequency of 0.097. Of the 53 Parkinson`s patients, 11 had the E4 allele for a frequency of 0.113. Thus our findings support the association of the ApoE4 allele with Alzheimer`s disease.« less

Genetic diversity of the merozoite surface protein-3 gene in Plasmodium falciparum populations in Thailand.

PubMed

Pattaradilokrat, Sittiporn; Sawaswong, Vorthon; Simpalipan, Phumin; Kaewthamasorn, Morakot; Siripoon, Napaporn; Harnyuttanakorn, Pongchai

2016-10-21

An effective malaria vaccine is an urgently needed tool to fight against human malaria, the most deadly parasitic disease of humans. One promising candidate is the merozoite surface protein-3 (MSP-3) of Plasmodium falciparum. This antigenic protein, encoded by the merozoite surface protein (msp-3) gene, is polymorphic and classified according to size into the two allelic types of K1 and 3D7. A recent study revealed that both the K1 and 3D7 alleles co-circulated within P. falciparum populations in Thailand, but the extent of the sequence diversity and variation within each allelic type remains largely unknown. The msp-3 gene was sequenced from 59 P. falciparum samples collected from five endemic areas (Mae Hong Son, Kanchanaburi, Ranong, Trat and Ubon Ratchathani) in Thailand and analysed for nucleotide sequence diversity, haplotype diversity and deduced amino acid sequence diversity. The gene was also subject to population genetic analysis (F st ) and neutrality tests (Tajima's D, Fu and Li D* and Fu and Li' F* tests) to determine any signature of selection. The sequence analyses revealed eight unique DNA haplotypes and seven amino acid sequence variants, with a haplotype and nucleotide diversity of 0.828 and 0.049, respectively. Neutrality tests indicated that the polymorphism detected in the alanine heptad repeat region of MSP-3 was maintained by positive diversifying selection, suggesting its role as a potential target of protective immune responses and supporting its role as a vaccine candidate. Comparison of MSP-3 variants among parasite populations in Thailand, India and Nigeria also inferred a close genetic relationship between P. falciparum populations in Asia. This study revealed the extent of the msp-3 gene diversity in P. falciparum in Thailand, providing the fundamental basis for the better design of future blood stage malaria vaccines against P. falciparum.

Genetic diversity based on SSR analysis of the cultured snakehead fish, Channa argus, (Channidae) in China.

PubMed

Zhu, S-R; Li, J-L; Xie, N; Zhu, L-M; Wang, Q; Yue, G-H

2014-02-13

The snakehead fish Channa argus is an important food fish in China. We identified six microsatellite loci for C. argus. These six microsatellite loci and four other microsatellite markers were used to analyze genetic diversity in four cultured populations of C. argus (SD, JX, HN, and ZJ) and determine their relationships. A total of 154 alleles were detected at the 10 microsatellite loci. The average expected and observed heterozygosities varied from 0.70-0.84 and 0.69-0.83, respectively, and polymorphism information content ranged between 0.66 and 0.82 in the four populations, indicating high genetic diversity. Population JX deviated from mutation-drift equilibrium and may have experienced a recent bottleneck. Analysis of pairwise genetic differentiation revealed FST values that ranged from 0.028 to 0.100, which indicates a moderate level of genetic differentiation. The largest distances were observed between populations HN and SD, whereas the smallest distances were obtained between populations HN and JX. Genetic clustering analysis demonstrated that the ZJ and HN populations probably share the same origin. This information about the genetic diversity within each of the four populations, and their genetic relationships will be useful for future genetic improvement of C. argus through selective breeding.

Divergent Hd1, Ghd7, and DTH7 Alleles Control Heading Date and Yield Potential of Japonica Rice in Northeast China.

PubMed

Ye, Jing; Niu, Xiaojun; Yang, Yaolong; Wang, Shan; Xu, Qun; Yuan, Xiaoping; Yu, Hanyong; Wang, Yiping; Wang, Shu; Feng, Yue; Wei, Xinghua

2018-01-01

The heading date is a vital factor in achieving a full rice yield. Cultivars with particular flowering behaviors have been artificially selected to survive in the long-day and low-temperature conditions of Northeast China. To dissect the genetic mechanism responsible for heading date in rice populations from Northeast China, association mapping was performed to identify major controlling loci. A genome-wide association study (GWAS) identified three genetic loci, Hd1 , Ghd7 , and DTH7 , using general and mixed linear models. The three genes were sequenced to analyze natural variations and identify their functions. Loss-of-function alleles of these genes contributed to early rice heading dates in the northern regions of Northeast China, while functional alleles promoted late rice heading dates in the southern regions of Northeast China. Selecting environmentally appropriate allele combinations in new varieties is recommended during breeding. Introducing the early indica rice's genetic background into Northeast japonica rice is a reasonable strategy for improving genetic diversity.

Discovery of Novel Bmy1 Alleles Increasing β-Amylase Activity in Chinese Landraces and Tibetan Wild Barley for Improvement of Malting Quality via MAS

PubMed Central

Gong, Xue; Westcott, Sharon; Zhang, Xiao-Qi; Yan, Guijun; Lance, Reg; Zhang, Guoping; Sun, Dongfa; Li, Chengdao

2013-01-01

China has a large barley germplasm collection which has not been well characterized and is therefore underutilized. The Bmy1 locus encoding the β-amylase enzyme on chromosome 4H has been well characterized in the worldwide barley germplasm collections due to its importance in the malting and brewing industry. The Bmy1 locus was chosen as an indicator to understand genetic potential for improvement of malting quality in Chinese landraces and Tibetan wild barley. The genetic diversity of 91 barley accessions was assessed using allele specific Multiplex-ready molecular markers. Eight accessions were further sequenced, based on the Multiplex-ready marker diversity for Bmy1 in the germplasm. Six of the eight accessions clustered together in a unique group, and showed similarities to ‘Haruna Nijo’, wild barley accession PI296896 and ‘Ashqelon’. Sequence comparisons with the known Bmy1 alleles identified not only the existing 13 amino acid substitutions, but also a new substitution positioned at A387T from a Chinese landrace W127, which has the highest β-amylase activity. Two new alleles/haplotypes namely Bmy1-Sd1c and Bmy1-Sd5 were designated based on different amino acid combinations. We identified new amino acid combination of C115, D165, V233, S347 and V430 in the germplasm. The broad variation in both β-amylase activity and amino acid composition provides novel alleles for the improvement of malting quality for different brewing styles, which indicates the high potential value of the Chinese landraces and Tibetan wild barley. PMID:24019884

Analysis of an "off-ladder" allele at the Penta D short tandem repeat locus.

PubMed

Yang, Y L; Wang, J G; Wang, D X; Zhang, W Y; Liu, X J; Cao, J; Yang, S L

2015-11-25

Kinship testing of a father and his son from Guangxi, China, the location of the Zhuang minority people, was performed using the PowerPlex® 18D System with a short tandem repeat typing kit. The results indicated that both the father and his son had an off-ladder allele at the Penta D locus, with a genetic size larger than that of the maximal standard allelic ladder. To further identify this locus, monogenic amplification, gene cloning, and genetic sequencing were performed. Sequencing analysis demonstrated that the fragment size of the Penta D-OL locus was 469 bp and the core sequence was [AAAGA]21, also called Penta D-21. The rare Penta D-21 allele was found to be distributed among the Zhuang population from the Guangxi Zhuang Autonomous Region of China; therefore, this study improved the range of DNA data available for this locus and enhanced our ability for individual identification of gene loci.

Conservation genetics of the alligator snapping turtle: cytonuclear evidence of range-wide bottleneck effects and unusually pronounced geographic structure

USGS Publications Warehouse

Echelle, A.A.; Hackler, J.C.; Lack, Justin B.; Ballard, S. R.; Roman, J.; Fox, S. F.; Leslie,, David M.; Van Den Bussche, Ronald A.

2010-01-01

A previous mtDNA study indicated that female-mediated gene flow was extremely rare among alligator snapping turtle populations in different drainages of the Gulf of Mexico. In this study, we used variation at seven microsatellite DNA loci to assess the possibility of male-mediated gene flow, we augmented the mtDNA survey with additional sampling of the large Mississippi River System, and we evaluated the hypothesis that the consistently low within-population mtDNA diversity reflects past population bottlenecks. The results show that dispersal between drainages of the Gulf of Mexico is rare (F STmsat  = 0.43, ΦSTmtDNA = 0.98). Past range-wide bottlenecks are indicated by several genetic signals, including low diversity for microsatellites (1.1–3.9 alleles/locus; H e = 0.06–0.53) and mtDNA (h = 0.00 for most drainages; π = 0.000–0.001). Microsatellite data reinforce the conclusion from mtDNA that the Suwannee River population might eventually be recognized as a distinct taxonomic unit. It was the only population showing fixation or near fixation for otherwise rare microsatellite alleles. Six evolutionarily significant units are recommended on the basis of reciprocal mtDNA monophyly and high levels of microsatellite DNA divergence.

Molecular characterization of allelic variants of (GATA)n microsatellite loci in parthenogenetic lizards Darevskia unisexualis (Lacertidae).

PubMed

Korchagin, V I; Badaeva, T N; Tokarskaya, O N; Martirosyan, I A; Darevsky, I S; Ryskov, A P

2007-05-01

Populations of parthenogenetic lizards of the genus Darevskia consist of genetically identical animals, and represent a unique model for studying the molecular mechanisms underlying the variability and evolution of hypervariable DNA repeats. As unisexual lineages, parthenogenetic lizards are characterized by some level of genetic diversity at microsatellite loci. We cloned and sequenced a number of (GATA)n microsatellite loci of Darevskia unisexualis. PCR products from these loci were also sequenced and the degree of intraspecific polymorphism was assessed. Among the five (GATA)n loci analysed, two (Du215 and Du281) were polymorphic. Cross-species analysis of Du215 and Du281 indicate that the priming sites at the D. unisexualis loci are conserved in the bisexual parental species, D. raddei and D. valentini. Sequencing the PCR products amplified from Du215 and Du281 and from monomorphic Du323 showed that allelic differences at the polymorphic loci are caused by microsatellite mutations and by point mutations in the flanking regions. The haplotypes identified among the allelic variants of Du281 and among its orthologues in the parental species provide new evidence of the cross-species origin of D. unisexualis. To our knowledge, these data are the first to characterize the nucleotide sequences of allelic variants at microsatellite loci within parthenogenetic vertebrate animals.

Marker-assisted selection for recognizing wheat mutant genotypes carrying HMW glutenin alleles related to baking quality.

PubMed

Zamani, Mohammad Javad; Bihamta, Mohammad Reza; Naserian Khiabani, Behnam; Tahernezhad, Zahra; Hallajian, Mohammad Taher; Shamsi, Marzieh Varasteh

2014-01-01

Allelic diversity of HMW glutenin loci in several studies revealed that allelic combinations affect dough quality. Dx5 + Dy10 subunits are related to good baking quality and Dx2 + Dy12 are related to undesirable baking quality. One of the most regular methods to evaluate the baking quality is SDS-PAGE which is used to improve baking quality labs. Marker-assisted selection is the method which can recognize the alleles related to baking quality and this method is based on polymerase chain reaction. 10 pairs of specific primers related to Dx2, Dx2.1, Dx5, Dy10, and Dy12 subunits were used for recognizing baking quality of some wheat varieties and some mutant genotypes. Only 5 pairs of them could show the specific bands. All subunits were recognized by the primers except Dx2.1. Some of the primers were extracted from previous studies and the others were designed based on D genome subunits of wheat. SDS-PAGE method accomplished having confidence in these marker's results. To realize the effect of mutation, seed storage proteins were measured. It showed that mutation had effect on the amount of seed storage protein on the mutant seeds (which showed polymorphism).

Erasure and reestablishment of random allelic expression imbalance after epigenetic reprogramming

PubMed Central

Jeffries, Aaron Richard; Uwanogho, Dafe Aghogho; Cocks, Graham; Perfect, Leo William; Dempster, Emma; Mill, Jonathan; Price, Jack

2016-01-01

Clonal level random allelic expression imbalance and random monoallelic expression provides cellular heterogeneity within tissues by modulating allelic dosage. Although such expression patterns have been observed in multiple cell types, little is known about when in development these stochastic allelic choices are made. We examine allelic expression patterns in human neural progenitor cells before and after epigenetic reprogramming to induced pluripotency, observing that loci previously characterized by random allelic expression imbalance (0.63% of expressed genes) are generally reset to a biallelic state in induced pluripotent stem cells (iPSCs). We subsequently neuralized the iPSCs and profiled isolated clonal neural stem cells, observing that significant random allelic expression imbalance is reestablished at 0.65% of expressed genes, including novel loci not found to show allelic expression imbalance in the original parental neural progenitor cells. Allelic expression imbalance was associated with altered DNA methylation across promoter regulatory regions, with clones characterized by skewed allelic expression being hypermethylated compared to their biallelic sister clones. Our results suggest that random allelic expression imbalance is established during lineage commitment and is associated with increased DNA methylation at the gene promoter. PMID:27539784

REVIEW-ARTICLE Intermediate alleles of Huntington's disease HTT gene in different populations worldwide: a systematic review.

PubMed

Apolinário, T A; Paiva, C L A; Agostinho, L A

2017-04-05

Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disorder caused by a dynamic mutation due to the expansion of CAG repeats in the HTT gene (4p16.3). The considered normal alleles have less than 27 CAG repeats. Intermediate alleles (IAs) show 27 to 35 CAG repeats and expanded alleles have more than 35 repeats. The IAs apparently have shown a normal phenotype. However, there are some reported associations between individuals that bear an IA and clinical HD signs, such as behavioral disturbs. The association of IAs with the presence of clinical signs gives clinical relevance to these patients. We emphasized the importance of determining the frequency of IA alleles in the general population as well as in HD families. Therefore, the aim of this study was to conduct a systematic review, in order to investigate the frequency of IAs in the overall chromosomes of different ethnic groups and of families with HD history worldwide as well as the frequency of individuals who bear the intermediate alleles. We searched indexed articles from the following electronic databases: U.S. National Library of Medicine and the National Institutes of Health (PubMed), Pubmed Central (PMC) and Virtual Health Library (VHL). Therefore, 488 articles were obtained and, of these, 33 had been published in more than one database. We accepted the article of only one database and ended up with 455 articles for this review. The frequency of IAs within the chromosomes of the general population ranged from 0.45 to 8.7% and of individuals with family history of HD ranged from 0.05 to 5.1%. The higher frequency of IAs in the general population (8.7%) was found in one Brazilian cohort.

Identification of four novel HLA-B alleles, B*1590, B*1591, B*2726, and B*4705, from an East African population by high-resolution sequence-based typing.

PubMed

Luo, M; Mao, X; Plummer, F A

2005-02-01

We report here four novel HLA-B alleles, B*1590, B*1591, B*2726, and B*4705, identified from an East African population during sequence-based HLA-B typing. The novel alleles were confirmed by sequencing two separate polymerase chain reaction products, and by molecular cloning and sequencing multiple clones. B*1590 is identical to B*1510 at exon 2 and exon 3, except for a difference (GCCGTC) at codon 158. Sequence differences at codon 152 (GAGGTG) and codon 167 (TGGTCG) differentiate B*1591 from B*1503 at exon 3. B*2726 is identical to B*2708 at exon 2 and exon 3, except for a difference (AAGCAG) at codon 70. B*4705 was identified in three Kenyan women. The allele is identical to B*47010101/02 at exon 2 and exon 3, except for differences at codon 97 (AGGAAT) and codon 99 (TTTTAT). These new alleles have been named by the WHO Nomenclature Committee. Identification of these novel HLA-B alleles reflects the genetic diversity of this East African population.

Phenotypic analysis of separation-of-function alleles of MEI-41, Drosophila ATM/ATR.

PubMed Central

Laurençon, Anne; Purdy, Amanda; Sekelsky, Jeff; Hawley, R Scott; Su, Tin Tin

2003-01-01

ATM/ATR kinases act as signal transducers in eukaryotic DNA damage and replication checkpoints. Mutations in ATM/ATR homologs have pleiotropic effects that range from sterility to increased killing by genotoxins in humans, mice, and Drosophila. Here we report the generation of a null allele of mei-41, Drosophila ATM/ATR homolog, and the use of it to document a semidominant effect on a larval mitotic checkpoint and methyl methanesulfonate (MMS) sensitivity. We also tested the role of mei-41 in a recently characterized checkpoint that delays metaphase/anaphase transition after DNA damage in cellular embryos. We then compare five existing mei-41 alleles to the null with respect to known phenotypes (female sterility, cell cycle checkpoints, and MMS resistance). We find that not all phenotypes are affected equally by each allele, i.e., the functions of MEI-41 in ensuring fertility, cell cycle regulation, and resistance to genotoxins are genetically separable. We propose that MEI-41 acts not in a single rigid signal transduction pathway, but in multiple molecular contexts to carry out its many functions. Sequence analysis identified mutations, which, for most alleles, fall in the poorly characterized region outside the kinase domain; this allowed us to tentatively identify additional functional domains of MEI-41 that could be subjected to future structure-function studies of this key molecule. PMID:12807779

Nucleotide diversity, natural variation, and evolution of Flexible culm-1 and Strong culm-2 lodging resistance genes in rice.

PubMed

Rashid, Muhammad Abdul Rehman; Zhao, Yan; Zhang, Hongliang; Li, Jinjie; Li, Zichao

2016-07-01

Lodging resistance is one of the vital traits in yield improvement and sustainability. Culm wall thickness, diameter, and strength are different traits that can govern the lodging resistance in rice. The genes SCM2 and FC1 have been isolated for culm thickness, strength, and flexibility, but their functional nucleotide variations were still unknown. We used a 13× deep sequence of 795 diverse genotypes to present the functional variation and SNP diversity in SCM2 and FC1. The major functional variant for the SCM2 gene was at position 27480181 and for the FC1 gene at position 31072992. Haplotype analysis of both genes provided their various allelic differences among haplotypes. SCM2 alleles further presented the evolution of Oryza sativa L. subsp. indica and subsp. japonica genomes from common parent in different geographical zones, while the haplotypes of FC1 suggested their evolution from different strains of the common parent Oryza rufipogon. SCM2 showed purifying selection and functional associations with rare alleles, while FC1 displayed balanced selection favored by multiple heterozygous alleles. Genotypes with an allelic combination of SCM2-3 and FC1-2 in japonica background exhibited striking resistance against lodging, which can be used in further breeding programs.

Mutant maize variety containing the glt1-1 allele

DOEpatents

Nelson, O.E.; Pan, D.

1994-07-19

A maize plant has in its genome a non-mutable form of a mutant allele designated vitX-8132. The allele is located at a locus designated as glt which conditions kernels having an altered starch characteristic. Maize plants including such a mutant allele produce a starch that does not increase in viscosity on cooling, after heating. 2 figs.

Mutant maize variety containing the glt1-1 allele

DOEpatents

Nelson, Oliver E.; Pan, David

1994-01-01

A maize plant has in its genome a non-mutable form of a mutant allele designated vitX-8132. The allele is located at a locus designated as glt which conditions kernels having an altered starch characteristic. Maize plants including such a mutant allele produce a starch that does not increase in viscosity on cooling, after heating.

Novel allelic variants in ACD6 cause hybrid necrosis in local collection of Arabidopsis thaliana.

PubMed

Świadek, Magdalena; Proost, Sebastian; Sieh, Daniela; Yu, Jing; Todesco, Marco; Jorzig, Christian; Rodriguez Cubillos, Andrés Eduardo; Plötner, Björn; Nikoloski, Zoran; Chae, Eunyoung; Giavalisco, Patrick; Fischer, Axel; Schröder, Florian; Kim, Sang-Tae; Weigel, Detlef; Laitinen, Roosa A E

2017-01-01

Hybrid necrosis is a common type of hybrid incompatibility in plants. This phenomenon is caused by deleterious epistatic interactions, resulting in spontaneous activation of plant defenses associated with leaf necrosis, stunted growth and reduced fertility in hybrids. Specific combinations of alleles of ACCELERATED CELL DEATH 6 (ACD6) have been shown to be a common cause of hybrid necrosis in Arabidopsis thaliana. Increased ACD6 activity confers broad-spectrum resistance against biotrophic pathogens but reduces biomass production. We generated 996 crosses among individuals derived from a single collection area around Tübingen (Germany) and screened them for hybrid necrosis. Necrotic hybrids were further investigated by genetic linkage, amiRNA silencing, genomic complementation and metabolic profiling. Restriction site associated DNA (RAD)-sequencing was used to understand genetic diversity in the collection sites containing necrosis-inducing alleles. Novel combinations of ACD6 alleles found in neighbouring stands were found to activate the A. thaliana immune system. In contrast to what we observed in controlled conditions, necrotic hybrids did not show reduced fitness in the field. Metabolic profiling revealed changes associated with the activation of the immune system in ACD6-dependent hybrid necrosis. This study expands our current understanding of the active role of ACD6 in mediating trade-offs between defense responses and growth in A.  thaliana. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Cross-Scale Analysis of the Region Effect on Vascular Plant Species Diversity in Southern and Northern European Mountain Ranges

PubMed Central

Lenoir, Jonathan; Gégout, Jean-Claude; Guisan, Antoine; Vittoz, Pascal; Wohlgemuth, Thomas; Zimmermann, Niklaus E.; Dullinger, Stefan; Pauli, Harald; Willner, Wolfgang; Grytnes, John-Arvid; Virtanen, Risto; Svenning, Jens-Christian

2010-01-01

Background The divergent glacial histories of southern and northern Europe affect present-day species diversity at coarse-grained scales in these two regions, but do these effects also penetrate to the more fine-grained scales of local communities? Methodology/Principal Findings We carried out a cross-scale analysis to address this question for vascular plants in two mountain regions, the Alps in southern Europe and the Scandes in northern Europe, using environmentally paired vegetation plots in the two regions (n = 403 in each region) to quantify four diversity components: (i) total number of species occurring in a region (total γ-diversity), (ii) number of species that could occur in a target plot after environmental filtering (habitat-specific γ-diversity), (iii) pair-wise species compositional turnover between plots (plot-to-plot β-diversity) and (iv) number of species present per plot (plot α-diversity). We found strong region effects on total γ-diversity, habitat-specific γ-diversity and plot-to-plot β-diversity, with a greater diversity in the Alps even towards distances smaller than 50 m between plots. In contrast, there was a slightly greater plot α-diversity in the Scandes, but with a tendency towards contrasting region effects on high and low soil-acidity plots. Conclusions/Significance We conclude that there are strong regional differences between coarse-grained (landscape- to regional-scale) diversity components of the flora in the Alps and the Scandes mountain ranges, but that these differences do not necessarily penetrate to the finest-grained (plot-scale) diversity component, at least not on acidic soils. Our findings are consistent with the contrasting regional Quaternary histories, but we also consider alternative explanatory models. Notably, ecological sorting and habitat connectivity may play a role in the unexpected limited or reversed region effect on plot α-diversity, and may also affect the larger-scale diversity components. For

Gut microbiomes of free-ranging and captive Namibian cheetahs: Diversity, putative functions and occurrence of potential pathogens.

PubMed

Wasimuddin; Menke, Sebastian; Melzheimer, Jörg; Thalwitzer, Susanne; Heinrich, Sonja; Wachter, Bettina; Sommer, Simone

2017-10-01

Although the significance of the gut microbiome for host health is well acknowledged, the impact of host traits and environmental factors on the interindividual variation of gut microbiomes of wildlife species is not well understood. Such information is essential; however, as changes in the composition of these microbial communities beyond the natural range might cause dysbiosis leading to increased susceptibility to infections. We examined the potential influence of sex, age, genetic relatedness, spatial tactics and the environment on the natural range of the gut microbiome diversity in free-ranging Namibian cheetahs (Acinonyx jubatus). We further explored the impact of an altered diet and frequent contact with roaming dogs and cats on the occurrence of potential bacterial pathogens by comparing free-ranging and captive individuals living under the same climatic conditions. Abundance patterns of particular bacterial genera differed between the sexes, and bacterial diversity and richness were higher in older (>3.5 years) than in younger individuals. In contrast, male spatial tactics, which probably influence host exposure to environmental bacteria, had no discernible effect on the gut microbiome. The profound resemblance of the gut microbiome of kin in contrast to nonkin suggests a predominant role of genetics in shaping bacterial community characteristics and functional similarities. We also detected various Operational Taxonomic Units (OTUs) assigned to potential pathogenic bacteria known to cause diseases in humans and wildlife species, such as Helicobacter spp., and Clostridium perfringens. Captive individuals did not differ in their microbial alpha diversity but exhibited higher abundances of OTUs related to potential pathogenic bacteria and shifts in disease-associated functional pathways. Our study emphasizes the need to integrate ecological, genetic and pathogenic aspects to improve our comprehension of the main drivers of natural variation and shifts in

Reduced Height (Rht) Alleles Affect Wheat Grain Quality.

PubMed

Casebow, Richard; Hadley, Caroline; Uppal, Rajneet; Addisu, Molla; Loddo, Stefano; Kowalski, Ania; Griffiths, Simon; Gooding, Mike

2016-01-01

The effects of dwarfing alleles (reduced height, Rht) in near isogenic lines on wheat grain quality are characterised in field experiments and related to effects on crop height, grain yield and GA-sensitivity. Alleles included those that conferred GA-insensitivity (Rht-B1b, Rht-B1c, Rht-D1b, Rht-D1c) as well as those that retained GA-sensitivity (rht(tall), Rht8, Rht8 + Ppd-D1a, Rht12). Full characterisation was facilitated by including factors with which the effects of Rht alleles are known to interact for grain yield (i.e. system, [conventional or organic]; tillage intensity [plough-based, minimum or zero]; nitrogen fertilizer level [0-450 kg N/ha]; and genetic backgrounds varying in height [cvs Maris Huntsman, Maris Widgeon, and Mercia]. Allele effects on mean grain weight and grain specific weight were positively associated with final crop height: dwarfing reduced these quality criteria irrespective of crop management or GA-sensitivity. In all but two experiments the effects of dwarfing alleles on grain nitrogen and sulphur concentrations were closely and negatively related to effects on grain yield, e.g. a quadratic relationship between grain yield and crop height manipulated by the GA-insensitive alleles was mirrored by quadratic relationships for nitrogen and sulphur concentrations: the highest yields and most dilute concentrations occurred around 80cm. In one of the two exceptional experiments the GA-insensitive Rht-B1b and Rht-B1c significantly (P<0.05) reduced grain nitrogen concentration in the absence of an effect on yield, and in the remaining experiment the GA-sensitive Rht8 significantly reduced both grain yield and grain nitrogen concentration simultaneously. When Rht alleles diluted grain nitrogen concentration, N:S ratios and SDS-sedimentation volumes were often improved. Hagberg falling number (HFN) was negatively related to crop height but benefits from dwarfing were only seen for GA-insensitive alleles. For HFN, therefore, there was the

Introducing close-range photogrammetry for characterizing forest understory plant diversity and surface fuel structure at fine scales

Treesearch

Benjamin C. Bright; E. Louise Loudermilk; Scott M. Pokswinski; Andrew T. Hudak; Joseph J. O' Brien

2016-01-01

Methods characterizing fine-scale fuels and plant diversity can advance understanding of plant-fire interactions across scales and help in efforts to monitor important ecosystems such as longleaf pine (Pinus palustris Mill.) forests of the southeastern United States. Here, we evaluate the utility of close-range photogrammetry for measuring fuels and plant...

Erasure and reestablishment of random allelic expression imbalance after epigenetic reprogramming.

PubMed

Jeffries, Aaron Richard; Uwanogho, Dafe Aghogho; Cocks, Graham; Perfect, Leo William; Dempster, Emma; Mill, Jonathan; Price, Jack

2016-10-01

Clonal level random allelic expression imbalance and random monoallelic expression provides cellular heterogeneity within tissues by modulating allelic dosage. Although such expression patterns have been observed in multiple cell types, little is known about when in development these stochastic allelic choices are made. We examine allelic expression patterns in human neural progenitor cells before and after epigenetic reprogramming to induced pluripotency, observing that loci previously characterized by random allelic expression imbalance (0.63% of expressed genes) are generally reset to a biallelic state in induced pluripotent stem cells (iPSCs). We subsequently neuralized the iPSCs and profiled isolated clonal neural stem cells, observing that significant random allelic expression imbalance is reestablished at 0.65% of expressed genes, including novel loci not found to show allelic expression imbalance in the original parental neural progenitor cells. Allelic expression imbalance was associated with altered DNA methylation across promoter regulatory regions, with clones characterized by skewed allelic expression being hypermethylated compared to their biallelic sister clones. Our results suggest that random allelic expression imbalance is established during lineage commitment and is associated with increased DNA methylation at the gene promoter. © 2016 Jeffries et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Maize ARGOS1 (ZAR1) transgenic alleles increase hybrid maize yield.

PubMed

Guo, Mei; Rupe, Mary A; Wei, Jun; Winkler, Chris; Goncalves-Butruille, Marymar; Weers, Ben P; Cerwick, Sharon F; Dieter, Jo Ann; Duncan, Keith E; Howard, Richard J; Hou, Zhenglin; Löffler, Carlos M; Cooper, Mark; Simmons, Carl R

2014-01-01

Crop improvement for yield and drought tolerance is challenging due to the complex genetic nature of these traits and environmental dependencies. This study reports that transgenic over-expression of Zea mays AR GOS1 (ZAR1) enhanced maize organ growth, grain yield, and drought-stress tolerance. The ZAR1 transgene exhibited environmental interactions, with yield increase under Temperate Dry and yield reduction under Temperate Humid or High Latitude environments. Native ZAR1 allele variation associated with drought-stress tolerance. Two founder alleles identified in the mid-maturity germplasm of North America now predominate in Pioneer's modern breeding programme, and have distinct proteins, promoters and expression patterns. These two major alleles show heterotic group partitioning, with one predominant in Pioneer's female and the other in the male heterotic groups, respectively. These two alleles also associate with favourable crop performance when heterozygous. Allele-specific transgene testing showed that, of the two alleles discussed here, each allele differed in their impact on yield and environmental interactions. Moreover, when transgenically stacked together the allelic pair showed yield and environmental performance advantages over either single allele, resembling heterosis effects. This work demonstrates differences in transgenic efficacy of native alleles and the differences reflect their association with hybrid breeding performance.

Maize ARGOS1 (ZAR1) transgenic alleles increase hybrid maize yield

PubMed Central

Guo, Mei

2014-01-01

Crop improvement for yield and drought tolerance is challenging due to the complex genetic nature of these traits and environmental dependencies. This study reports that transgenic over-expression of Zea mays ARGOS1 (ZAR1) enhanced maize organ growth, grain yield, and drought-stress tolerance. The ZAR1 transgene exhibited environmental interactions, with yield increase under Temperate Dry and yield reduction under Temperate Humid or High Latitude environments. Native ZAR1 allele variation associated with drought-stress tolerance. Two founder alleles identified in the mid-maturity germplasm of North America now predominate in Pioneer’s modern breeding programme, and have distinct proteins, promoters and expression patterns. These two major alleles show heterotic group partitioning, with one predominant in Pioneer’s female and the other in the male heterotic groups, respectively. These two alleles also associate with favourable crop performance when heterozygous. Allele-specific transgene testing showed that, of the two alleles discussed here, each allele differed in their impact on yield and environmental interactions. Moreover, when transgenically stacked together the allelic pair showed yield and environmental performance advantages over either single allele, resembling heterosis effects. This work demonstrates differences in transgenic efficacy of native alleles and the differences reflect their association with hybrid breeding performance. PMID:24218327

Genetic diversity analysis of common beans based on molecular markers

PubMed Central

Gill-Langarica, Homar R.; Muruaga-Martínez, José S.; Vargas-Vázquez, M.L. Patricia; Rosales-Serna, Rigoberto; Mayek-Pérez, Netzahualcoyotl

2011-01-01

A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5% polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation. PMID:22215964

Genetic diversity analysis of common beans based on molecular markers.

PubMed

Gill-Langarica, Homar R; Muruaga-Martínez, José S; Vargas-Vázquez, M L Patricia; Rosales-Serna, Rigoberto; Mayek-Pérez, Netzahualcoyotl

2011-10-01

A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5% polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation.

Genetic Diversity and Population Structure of the Rare and Endangered Plant Species Pulsatilla patens (L.) Mill in East Central Europe.

PubMed

Szczecińska, Monika; Sramko, Gabor; Wołosz, Katarzyna; Sawicki, Jakub

2016-01-01

Pulsatilla patens s.s. is a one of the most endangered plant species in Europe. The present range of this species in Europe is highly fragmented and the size of the populations has been dramatically reduced in the past 50 years. The rapid disappearance of P. patens localities in Europe has prompted the European Commission to initiate active protection of this critically endangered species. The aim of this study was to estimate the degree and distribution of genetic diversity within European populations of this endangered species. We screened 29 populations of P. patens using a set of six microsatellite primers. The results of our study indicate that the analyzed populations are characterized by low levels of genetic diversity (Ho = 0.005) and very high levels of inbreeding (FIS = 0.90). These results suggest that genetic erosion could be partially responsible for the lower fitness in smaller populations of this species. Private allelic richness was very low, being as low as 0.00 for most populations. Average genetic diversity over loci and mean number of alleles in P. patens populations were significantly correlated with population size, suggesting severe genetic drift. The results of AMOVA point to higher levels of variation within populations than between populations.The results of Structure and PCoA analyses suggest that the genetic structure of the studied P. patens populations fall into three clusters corresponding to geographical regions. The most isolated populations (mostly from Romania) formed a separate group with a homogeneous gene pool located at the southern, steppic part of the distribution range. Baltic, mostly Polish, populations fall into two genetic groups which were not fully compatible with their geographic distribution.Our results indicate the serious genetic depauperation of P. patens in the western part of its range, even hinting at an ongoing extinction vortex. Therefore, special conservation attention is required to maintain the populations

Genetic diversity and relationship analysis of Gossypium arboreum accessions.

PubMed

Liu, F; Zhou, Z L; Wang, C Y; Wang, Y H; Cai, X Y; Wang, X X; Zhang, Z S; Wang, K B

2015-11-19

Simple sequence repeat techniques were used to identify the genetic diversity of 101 Gossypium arboreum accessions collected from India, Vietnam, and the southwest of China (Guizhou, Guangxi, and Yunnan provinces). Twenty-six pairs of SSR primers produced a total of 103 polymorphic loci with an average of 3.96 polymorphic loci per primer. The average of the effective number of alleles, Nei's gene diversity, and Shannon's information index were 0.59, 0.2835, and 0.4361, respectively. The diversity varied among different geographic regions. The result of principal component analysis was consistent with that of unweighted pair group method with arithmetic mean clustering analysis. The 101 G. arboreum accessions were clustered into 2 groups.

Balancing selection is common in the extended MHC region but most alleles with opposite risk profile for autoimmune diseases are neutrally evolving

PubMed Central

2011-01-01

Background Several susceptibility genetic variants for autoimmune diseases have been identified. A subset of these polymorphisms displays an opposite risk profile in different autoimmune conditions. This observation open interesting questions on the evolutionary forces shaping the frequency of these alleles in human populations. We aimed at testing the hypothesis whereby balancing selection has shaped the frequency of opposite risk alleles. Results Since balancing selection signatures are expected to extend over short genomic portions, we focused our analyses on 11 regions carrying putative functional polymorphisms that may represent the disease variants (and the selection targets). No exceptional nucleotide diversity was observed for ZSCAN23, HLA-DMB, VARS2, PTPN22, BAT3, C6orf47, and IL10; summary statistics were consistent with evolutionary neutrality for these gene regions. Conversely, CDSN/PSORS1C1, TRIM10/TRIM40, BTNL2, and TAP2 showed extremely high nucleotide diversity and most tests rejected neutrality, suggesting the action of balancing selection. For TAP2 and BTNL2 these signatures are not secondary to linkage disequilibrium with HLA class II genes. Nonetheless, with the exception of variants in TRIM40 and CDSN, our data suggest that opposite risk SNPs are not selection targets but rather have accumulated as neutral variants. Conclusion Data herein indicate that balancing selection is common within the extended MHC region and involves several non-HLA loci. Yet, the evolutionary history of most SNPs with an opposite effect for autoimmune diseases is consistent with evolutionary neutrality. We suggest that variants with an opposite effect on autoimmune diseases should not be considered a distinct class of disease alleles from the evolutionary perspective and, in a few cases, the opposite effect on distinct diseases may derive from complex haplotype structures in regions with high genetic diversity. PMID:21682861

Genetic diversity is related to climatic variation and vulnerability in threatened bull trout

USGS Publications Warehouse

Kovach, Ryan; Muhlfeld, Clint C.; Wade, Alisa A.; Hand, Brian K.; Whited, Diane C.; DeHaan, Patrick W.; Al-Chokhachy, Robert K.; Luikart, Gordon

2015-01-01

Understanding how climatic variation influences ecological and evolutionary processes is crucial for informed conservation decision-making. Nevertheless, few studies have measured how climatic variation influences genetic diversity within populations or how genetic diversity is distributed across space relative to future climatic stress. Here, we tested whether patterns of genetic diversity (allelic richness) were related to climatic variation and habitat features in 130 bull trout (Salvelinus confluentus) populations from 24 watersheds (i.e., ~4–7th order river subbasins) across the Columbia River Basin, USA. We then determined whether bull trout genetic diversity was related to climate vulnerability at the watershed scale, which we quantified on the basis of exposure to future climatic conditions (projected scenarios for the 2040s) and existing habitat complexity. We found a strong gradient in genetic diversity in bull trout populations across the Columbia River Basin, where populations located in the most upstream headwater areas had the greatest genetic diversity. After accounting for spatial patterns with linear mixed models, allelic richness in bull trout populations was positively related to habitat patch size and complexity, and negatively related to maximum summer temperature and the frequency of winter flooding. These relationships strongly suggest that climatic variation influences evolutionary processes in this threatened species and that genetic diversity will likely decrease due to future climate change. Vulnerability at a watershed scale was negatively correlated with average genetic diversity (r = −0.77;P < 0.001); watersheds containing populations with lower average genetic diversity generally had the lowest habitat complexity, warmest stream temperatures, and greatest frequency of winter flooding. Together, these findings have important conservation implications for bull trout and other imperiled species. Genetic diversity is already

Examination of Allelic Variation at the Hexokinase Loci of DROSOPHILA PSEUDOOBSCURA and D. PERSIMILIS by Different Methods

PubMed Central

Beckenbach, Andrew T.; Prakash, Satya

1977-01-01

Recently a number of electrophoretic techniques have been applied to reveal the presence of additional genetic variation among the electrophoretic mobility classes of the highly polymorphic xanthine dehydrogenase (XDH ) and esterase-5 (est-5) loci. We examined the hexokinase loci of Drosophila pseudoobscura and D. persimilis using a variety of techniques to determine whether further allelic variation could be revealed for these much less polymorphic loci and to analyze the nature of the known variation at the hexokinase-1 (hex-1) locus. The following studies were conducted: 135 strains of the two species from six localities were examined with buffer pH ranging from 5.5 to 10.0; 40 strains of D. pseudoobscura and 9 strains of D. persimilis from Mather were studied using starch gel concentrations ranging from 8.5 to 15.5% and were examined for differences in heat stability and reactivity to the thiol reagent pCMSA; strains were also tested for susceptibility to urea denaturation and differences in relative activities. Major findings of the work are: (1) No additional allelic variation could be detected at any of the hexokinase loci by applying these techniques. The finding of abundant hidden genetic variation in XDH and est-5 does not extend to all enzyme loci. (2) Evidence from studies using pCMSA indicates that the hex-1 alleles 0.6, 0.8, 1.0 and 1.2 of the two species form a series of unit charge steps. Since the 0.94 allele of D. persimilis has mobility intermediate between 0.8 and 1.0, it is argued that routine electrophoretic techniques are sensitive to at least some conservative amino acid substitutions. (3) Strong correlations were found at the hex-1 locus between low allelic frequency, reduced relative activity and reduced stability to heat and urea denaturation. Since the three sibling species, D. pseudoobscura, D. persimilis and D. miranda, all appear to share a common high frequency allele (1.0) at that locus, these findings are taken as evidence that the

Restricted VH gene usage and generation of antibody diversity in rabbit.

PubMed

Knight, K L

1992-01-01

The presence of VHa allotypic specificities on nearly all rabbit Ig molecules has perplexed immunologists for many years. How could these allotypic specificities be inherited as if controlled by alleles if the germline has hundreds of VHa allotype-encoding genes and if most of these genes are used in VDJ gene rearrangements. I review recent data indicating that the allelic inheritance of the VHa allotypes can be explained by preferential utilization of the D-proximal VH gene VH1 in VDJ gene rearrangements. The preferential usage of one VH gene, however, limits the contribution of combinatorial joining of multiple VH, D and JH gene segments to the generation of antibody diversity. The roles of somatic gene conversion and somatic mutation in generating antibody diversity are discussed. Further, the limited usage of germline VH genes in normal, allotype-suppressed and the mutant Alicia rabbit as well as the molecular basis of latent allotypes and VH/CH recombinants is reviewed.

Analysis of Plasmodium falciparum diversity in natural infections by deep sequencing

PubMed Central

Manske, Magnus; Miotto, Olivo; Campino, Susana; Auburn, Sarah; Almagro-Garcia, Jacob; Maslen, Gareth; O’Brien, Jack; Djimde, Abdoulaye; Doumbo, Ogobara; Zongo, Issaka; Ouedraogo, Jean-Bosco; Michon, Pascal; Mueller, Ivo; Siba, Peter; Nzila, Alexis; Borrmann, Steffen; Kiara, Steven M.; Marsh, Kevin; Jiang, Hongying; Su, Xin-Zhuan; Amaratunga, Chanaki; Fairhurst, Rick; Socheat, Duong; Nosten, Francois; Imwong, Mallika; White, Nicholas J.; Sanders, Mandy; Anastasi, Elisa; Alcock, Dan; Drury, Eleanor; Oyola, Samuel; Quail, Michael A.; Turner, Daniel J.; Rubio, Valentin Ruano; Jyothi, Dushyanth; Amenga-Etego, Lucas; Hubbart, Christina; Jeffreys, Anna; Rowlands, Kate; Sutherland, Colin; Roper, Cally; Mangano, Valentina; Modiano, David; Tan, John C.; Ferdig, Michael T.; Amambua-Ngwa, Alfred; Conway, David J.; Takala-Harrison, Shannon; Plowe, Christopher V.; Rayner, Julian C.; Rockett, Kirk A.; Clark, Taane G.; Newbold, Chris I.; Berriman, Matthew; MacInnis, Bronwyn; Kwiatkowski, Dominic P.

2013-01-01

Malaria elimination strategies require surveillance of the parasite population for genetic changes that demand a public health response, such as new forms of drug resistance. 1,2 Here we describe methods for large-scale analysis of genetic variation in Plasmodium falciparum by deep sequencing of parasite DNA obtained from the blood of patients with malaria, either directly or after short term culture. Analysis of 86,158 exonic SNPs that passed genotyping quality control in 227 samples from Africa, Asia and Oceania provides genome-wide estimates of allele frequency distribution, population structure and linkage disequilibrium. By comparing the genetic diversity of individual infections with that of the local parasite population, we derive a metric of within-host diversity that is related to the level of inbreeding in the population. An open-access web application has been established for exploration of regional differences in allele frequency and of highly differentiated loci in the P. falciparum genome. PMID:22722859

Genome-wide association study identifies HLA 8.1 ancestral haplotype alleles as major genetic risk factors for myositis phenotypes.

PubMed

Miller, F W; Chen, W; O'Hanlon, T P; Cooper, R G; Vencovsky, J; Rider, L G; Danko, K; Wedderburn, L R; Lundberg, I E; Pachman, L M; Reed, A M; Ytterberg, S R; Padyukov, L; Selva-O'Callaghan, A; Radstake, T R; Isenberg, D A; Chinoy, H; Ollier, W E R; Scheet, P; Peng, B; Lee, A; Byun, J; Lamb, J A; Gregersen, P K; Amos, C I

2015-10-01

Autoimmune muscle diseases (myositis) comprise a group of complex phenotypes influenced by genetic and environmental factors. To identify genetic risk factors in patients of European ancestry, we conducted a genome-wide association study (GWAS) of the major myositis phenotypes in a total of 1710 cases, which included 705 adult dermatomyositis, 473 juvenile dermatomyositis, 532 polymyositis and 202 adult dermatomyositis, juvenile dermatomyositis or polymyositis patients with anti-histidyl-tRNA synthetase (anti-Jo-1) autoantibodies, and compared them with 4724 controls. Single-nucleotide polymorphisms showing strong associations (P<5×10(-8)) in GWAS were identified in the major histocompatibility complex (MHC) region for all myositis phenotypes together, as well as for the four clinical and autoantibody phenotypes studied separately. Imputation and regression analyses found that alleles comprising the human leukocyte antigen (HLA) 8.1 ancestral haplotype (AH8.1) defined essentially all the genetic risk in the phenotypes studied. Although the HLA DRB1*03:01 allele showed slightly stronger associations with adult and juvenile dermatomyositis, and HLA B*08:01 with polymyositis and anti-Jo-1 autoantibody-positive myositis, multiple alleles of AH8.1 were required for the full risk effects. Our findings establish that alleles of the AH8.1 comprise the primary genetic risk factors associated with the major myositis phenotypes in geographically diverse Caucasian populations.

Genome-wide Association Study Identifies HLA 8.1 Ancestral Haplotype Alleles as Major Genetic Risk Factors for Myositis Phenotypes

PubMed Central

Miller, Frederick W.; Chen, Wei; O’Hanlon, Terrance P.; Cooper, Robert G.; Vencovsky, Jiri; Rider, Lisa G.; Danko, Katalin; Wedderburn, Lucy R.; Lundberg, Ingrid E.; Pachman, Lauren M.; Reed, Ann M.; Ytterberg, Steven R.; Padyukov, Leonid; Selva-O’Callaghan, Albert; Radstake, Timothy R.; Isenberg, David A.; Chinoy, Hector; Ollier, William E.R.; Scheet, Paul; Peng, Bo; Lee, Annette; Byun, Jinyoung; Lamb, Janine A.; Gregersen, Peter K.; Amos, Christopher I.

2016-01-01

Autoimmune muscle diseases (myositis) comprise a group of complex phenotypes influenced by genetic and environmental factors. To identify genetic risk factors in patients of European ancestry, we conducted a genome-wide association study (GWAS) of the major myositis phenotypes in a total of 1710 cases, which included 705 adult dermatomyositis; 473 juvenile dermatomyositis; 532 polymyositis; and 202 adult dermatomyositis, juvenile dermatomyositis or polymyositis patients with anti-histidyl tRNA synthetase (anti-Jo-1) autoantibodies, and compared them with 4724 controls. Single-nucleotide polymorphisms showing strong associations (P < 5 × 10−8) in GWAS were identified in the major histocompatibility complex (MHC) region for all myositis phenotypes together, as well as for the four clinical and autoantibody phenotypes studied separately. Imputation and regression analyses found that alleles comprising the human leukocyte antigen (HLA) 8.1 ancestral haplotype (AH8.1) defined essentially all the genetic risk in the phenotypes studied. Although the HLA DRB1*03:01 allele showed slightly stronger associations with adult and juvenile dermatomyositis, and HLA B*08:01 with polymyositis and anti-Jo-1 autoantibody-positive myositis, multiple alleles of AH8.1 were required for the full risk effects. Our findings establish that alleles of the AH8.1haplotype comprise the primary genetic risk factors associated with the major myositis phenotypes in geographically diverse Caucasian populations. PMID:26291516

Development of MHC-Linked Microsatellite Markers in the Domestic Cat and Their Use to Evaluate MHC Diversity in Domestic Cats, Cheetahs, and Gir Lions

PubMed Central

Morris, Katrina M.; Kirby, Katherine; Beatty, Julia A.; Barrs, Vanessa R.; Cattley, Sonia; David, Victor; O’Brien, Stephen J.; Menotti-Raymond, Marilyn

2014-01-01

Diversity within the major histocompatibility complex (MHC) reflects the immunological fitness of a population. MHC-linked microsatellite markers provide a simple and an inexpensive method for studying MHC diversity in large-scale studies. We have developed 6 MHC-linked microsatellite markers in the domestic cat and used these, in conjunction with 5 neutral microsatellites, to assess MHC diversity in domestic mixed breed (n = 129) and purebred Burmese (n = 61) cat populations in Australia. The MHC of outbred Australian cats is polymorphic (average allelic richness = 8.52), whereas the Burmese population has significantly lower MHC diversity (average allelic richness = 6.81; P < 0.01). The MHC-linked microsatellites along with MHC cloning and sequencing demonstrated moderate MHC diversity in cheetahs (n = 13) and extremely low diversity in Gir lions (n = 13). Our MHC-linked microsatellite markers have potential future use in diversity and disease studies in other populations and breeds of cats as well as in wild felid species. PMID:24620003

Identifying Darwinian selection acting on different human APOL1 variants among diverse African populations.

PubMed

Ko, Wen-Ya; Rajan, Prianka; Gomez, Felicia; Scheinfeldt, Laura; An, Ping; Winkler, Cheryl A; Froment, Alain; Nyambo, Thomas B; Omar, Sabah A; Wambebe, Charles; Ranciaro, Alessia; Hirbo, Jibril B; Tishkoff, Sarah A

2013-07-11

Disease susceptibility can arise as a consequence of adaptation to infectious disease. Recent findings have suggested that higher rates of chronic kidney disease (CKD) in individuals with recent African ancestry might be attributed to two risk alleles (G1 and G2) at the serum-resistance-associated (SRA)-interacting-domain-encoding region of APOL1. These two alleles appear to have arisen adaptively, possibly as a result of their protective effects against human African trypanosomiasis (HAT), or African sleeping sickness. In order to explore the distribution of potential functional variation at APOL1, we studied nucleotide variation in 187 individuals across ten geographically and genetically diverse African ethnic groups with exposure to two Trypanosoma brucei subspecies that cause HAT. We observed unusually high levels of nonsynonymous polymorphism in the regions encoding the functional domains that are required for lysing parasites. Whereas allele frequencies of G2 were similar across all populations (3%-8%), the G1 allele was only common in the Yoruba (39%). Additionally, we identified a haplotype (termed G3) that contains a nonsynonymous change at the membrane-addressing-domain-encoding region of APOL1 and is present in all populations except for the Yoruba. Analyses of long-range patterns of linkage disequilibrium indicate evidence of recent selection acting on the G3 haplotype in Fulani from Cameroon. Our results indicate that the G1 and G2 variants in APOL1 are geographically restricted and that there might be other functional variants that could play a role in HAT resistance and CKD risk in African populations. Copyright © 2013 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Aligning molecular studies of mycorrhizal fungal diversity with ecologically important levels of diversity in ecosystems

PubMed Central

Sanders, Ian R; Rodriguez, Alia

2016-01-01

Arbuscular mycorrhizal fungi (AMF) occur in the roots of most plants and are an ecologically important component of the soil microbiome. Richness of AMF taxa is a strong driver of plant diversity and productivity, thus providing a rationale for characterizing AMF diversity in natural ecosystems. Consequently, a large number of molecular studies on AMF community composition are currently underway. Most published studies, at best, only address species or genera-level resolution. However, several experimental studies indicate that variation in plant performance is large among plants colonised by different individuals of one AMF species. Thus, there is a potential disparity between how molecular community ecologists are currently describing AMF diversity and the level of AMF diversity that may actually be ecologically relevant. We propose a strategy to find many polymorphic loci that can define within-species genetic variability within AMF, or at any level of resolution desired within the Glomermycota. We propose that allele diversity at the intraspecific level could then be measured for target AMF groups, or at other levels of resolution, in environmental DNA samples. Combining the use of such markers with experimental studies on AMF diversity would help to elucidate the most important level(s) of AMF diversity in plant communities. Our goal is to encourage ecologists who are trying to explain how mycorrhizal fungal communities are structured to take an approach that could also yield meaningful information that is relevant to the diversity, functioning and productivity of ecosystems. PMID:27128992

A molecular analysis of the patterns of genetic diversity in local chickens from western Algeria in comparison with commercial lines and wild jungle fowls.

PubMed

Mahammi, F Z; Gaouar, S B S; Laloë, D; Faugeras, R; Tabet-Aoul, N; Rognon, X; Tixier-Boichard, M; Saidi-Mehtar, N

2016-02-01

The objectives of this study were to characterize the genetic variability of village chickens from three agro-ecological regions of western Algeria: coastal (CT), inland plains (IP) and highlands (HL), to reveal any underlying population structure, and to evaluate potential genetic introgression from commercial lines into local populations. A set of 233 chickens was genotyped with a panel of 23 microsatellite markers. Geographical coordinates were individually recorded. Eight reference populations were included in the study to investigate potential gene flow: four highly selected commercial pure lines and four lines of French slow-growing chickens. Two populations of wild red jungle fowls were also genotyped to compare the range of diversity between domestic and wild fowls. A genetic diversity analysis was conducted both within and between populations. Multivariate redundancy analyses were performed to assess the relative influence of geographical location among Algerian ecotypes. The results showed a high genetic variability within the Algerian population, with 184 alleles and a mean number of 8.09 alleles per locus. The values of heterozygosity (He and Ho) ranged from 0.55 to 0.62 in Algerian ecotypes and were smaller than values found in Jungle fowl populations and higher than values found in commercial populations. Although the structuring analysis of genotypes did not reveal clear subpopulations within Algerian ecotypes, the supervised approach using geographical data showed a significant (p < 0.01) differentiation between the three ecotypes which was mainly due to altitude. Thus, the genetic diversity of Algerian ecotypes may be under the influence of two factors with contradictory effects: the geographical location and climatic conditions may induce some differentiation, whereas the high level of exchanges and gene flow may suppress it. Evidence of gene flow between commercial and Algerian local populations was observed, which may be due to unrecorded

Genetic diversity analysis in the section Caulorrhizae (genus Arachis) using microsatellite markers.

PubMed

Palmieri, Darío A; Bechara, Marcelo D; Curi, Rogério A; Monteiro, Jomar P; Valente, Sérgio E S; Gimenes, Marcos A; Lopes, Catalina R

2010-01-01

Diversity in 26 microsatellite loci from section Caulorrhizae germplasm was evaluated by using 33 accessions of A. pintoi Krapov. & W.C. Gregory and ten accessions of Arachis repens Handro. Twenty loci proved to be polymorphic and a total of 196 alleles were detected with an average of 9.8 alleles per locus. The variability found in those loci was greater than the variability found using morphological characters, seed storage proteins and RAPD markers previously used in this germplasm. The high potential of these markers to detect species-specific alleles and discriminate among accessions was demonstrated. The set of microsatellite primer pairs developed by our group for A. pintoi are useful molecular tools for evaluating Section Caulorrhizae germplasm, as well as that of species belonging to other Arachis sections.

Genetic diversity analysis in the section Caulorrhizae (genus Arachis) using microsatellite markers

PubMed Central

2010-01-01

Diversity in 26 microsatellite loci from section Caulorrhizae germplasm was evaluated by using 33 accessions of A. pintoi Krapov. & W.C. Gregory and ten accessions of Arachis repens Handro. Twenty loci proved to be polymorphic and a total of 196 alleles were detected with an average of 9.8 alleles per locus. The variability found in those loci was greater than the variability found using morphological characters, seed storage proteins and RAPD markers previously used in this germplasm. The high potential of these markers to detect species-specific alleles and discriminate among accessions was demonstrated. The set of microsatellite primer pairs developed by our group for A. pintoi are useful molecular tools for evaluating Section Caulorrhizae germplasm, as well as that of species belonging to other Arachis sections. PMID:21637613

MHC class II B diversity in blue tits: a preliminary study.

PubMed

Aguilar, Juan Rivero-de; Schut, Elske; Merino, Santiago; Martínez, Javier; Komdeur, Jan; Westerdahl, Helena

2013-07-01

In this study, we partly characterize major histocompatibility complex (MHC) class II B in the blue tit (Cyanistes caeruleus). A total of 22 individuals from three different European locations: Spain, The Netherlands, and Sweden were screened for MHC allelic diversity. The MHC genes were investigated using both PCR-based methods and unamplified genomic DNA with restriction fragment length polymorphism (RFLP) and southern blots. A total of 13 different exon 2 sequences were obtained independently from DNA and/or RNA, thus confirming gene transcription and likely functionality of the genes. Nine out of 13 alleles were found in more than one country, and two alleles appeared in all countries. Positive selection was detected in the region coding for the peptide binding region (PBR). A maximum of three alleles per individual was detected by sequencing and the RFLP pattern consisted of 4-7 fragments, indicating a minimum number of 2-4 loci per individual. A phylogenetic analysis, demonstrated that the blue tit sequences are divergent compared to sequences from other passerines resembling a different MHC lineage than those possessed by most passerines studied to date.

The evolution of hyperactivity, impulsivity and cognitive diversity

PubMed Central

Williams, Jonathan; Taylor, Eric

2005-01-01

The evolutionary status of attention deficit/hyperactivity disorder (ADHD) is central to assessments of whether modern society has created it, either physically or socially; and is potentially useful in understanding its neurobiological basis and treatment. The high prevalence of ADHD (5–10%) and its association with the seven-repeat allele of DRD4, which is positively selected in evolution, raise the possibility that ADHD increases the reproductive fitness of the individual, and/or the group. However, previous suggestions of evolutionary roles for ADHD have not accounted for its confinement to a substantial minority. Because one of the key features of ADHD is its diversity, and many benefits of population diversity are well recognized (as in immunity), we study the impact of groups' behavioural diversity on their fitness. Diversity occurs along many dimensions, and for simplicity we choose unpredictability (or variability), excess of which is a well-established characteristic of ADHD. Simulations of the Changing Food group task show that unpredictable behaviour by a minority optimizes results for the group. Characteristics of such group exploration tasks are risk-taking, in which costs are borne mainly by the individual; and information-sharing, in which benefits accrue to the entire group. Hence, this work is closely linked to previous studies of evolved altruism. We conclude that even individually impairing combinations of genes, such as ADHD, can carry specific benefits for society, which can be selected for at that level, rather than being merely genetic coincidences with effects confined to the individual. The social benefits conferred by diversity occur both inside and outside the ‘normal’ range, and these may be distinct. This view has the additional merit of offering explanations for the prevalence, sex and age distribution, severity distribution and heterogeneity of ADHD. PMID:16849269

Heterogenous Distribution of MTHFR Gene Variants among Mestizos and Diverse Amerindian Groups from Mexico

PubMed Central

Contreras-Cubas, Cecilia; Sánchez-Hernández, Beatríz E.; García-Ortiz, Humberto; Martínez-Hernández, Angélica; Barajas-Olmos, Francisco; Cid, Miguel; Mendoza-Caamal, Elvia C.; Centeno-Cruz, Federico; Ortiz-Cruz, Gabriela; Jiménez-López, José Concepción; Córdova, Emilio J.; Salas-Bautista, Eva Gabriela; Saldaña-Alvarez, Yolanda; Fernández-López, Juan Carlos; Mutchinick, Osvaldo M.

2016-01-01

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in folate metabolism. Folate deficiency has been related to several conditions, including neural tube defects (NTDs) and cardiovascular diseases. Hence, MTHFR genetic variants have been studied worldwide, particularly the C677T and A1298C. We genotyped the C677T and A1298C MTHFR polymorphisms in Mexican Amerindians (MAs), from the largest sample included in a genetic study (n = 2026, from 62 ethnic groups), and in a geographically-matched Mexican Mestizo population (MEZ, n = 638). The 677T allele was most frequent in Mexican individuals, particularly in MAs. The frequency of this allele in both MAs and MEZs was clearly enriched in the South region of the country, followed by the Central East and South East regions. In contrast, the frequency of the 1298C risk allele in Mexicans was one of the lowest in the world. Both in MAs and MEZs the variants 677T and 1298C displayed opposite allele frequency gradients from southern to northern Mexico. Our findings suggest that in Mestizos the 677T allele was derived from Amerindians while the 1298C allele was a European contribution. Some subgroups showed an allele frequency distribution that highlighted their genetic diversity. Notably, the distribution of the frequency of the 677T allele was consistent with that of the high incidence of NTDs reported in MEZ. PMID:27649570

Population-based analysis of Alzheimer's disease risk alleles implicates genetic interactions.

PubMed

Ebbert, Mark T W; Ridge, Perry G; Wilson, Andrew R; Sharp, Aaron R; Bailey, Matthew; Norton, Maria C; Tschanz, JoAnn T; Munger, Ronald G; Corcoran, Christopher D; Kauwe, John S K

2014-05-01

Reported odds ratios and population attributable fractions (PAF) for late-onset Alzheimer's disease (LOAD) risk loci (BIN1, ABCA7, CR1, MS4A4E, CD2AP, PICALM, MS4A6A, CD33, and CLU) come from clinically ascertained samples. Little is known about the combined PAF for these LOAD risk alleles and the utility of these combined markers for case-control prediction. Here we evaluate these loci in a large population-based sample to estimate PAF and explore the effects of additive and nonadditive interactions on LOAD status prediction performance. 2419 samples from the Cache County Memory Study were genotyped for APOE and nine LOAD risk loci from AlzGene.org. We used logistic regression and receiver operator characteristic analysis to assess the LOAD status prediction performance of these loci using additive and nonadditive models and compared odds ratios and PAFs between AlzGene.org and Cache County. Odds ratios were comparable between Cache County and AlzGene.org when identical single nucleotide polymorphisms were genotyped. PAFs from AlzGene.org ranged from 2.25% to 37%; those from Cache County ranged from .05% to 20%. Including non-APOE alleles significantly improved LOAD status prediction performance (area under the curve = .80) over APOE alone (area under the curve = .78) when not constrained to an additive relationship (p < .03). We identified potential allelic interactions (p values uncorrected): CD33-MS4A4E (synergy factor = 5.31; p < .003) and CLU-MS4A4E (synergy factor = 3.81; p < .016). Although nonadditive interactions between loci significantly improve diagnostic ability, the improvement does not reach the desired sensitivity or specificity for clinical use. Nevertheless, these results suggest that understanding gene-gene interactions may be important in resolving Alzheimer's disease etiology. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Genetic diversity and genetic relationships of japonica rice varieties in Northeast Asia based on SSR markers

PubMed Central

Wang, Jingguo; Jiang, Tingbo; Zou, Detang; Zhao, Hongwei; Li, Qiang; Liu, Hualong; Zhou, Changjun

2014-01-01

Genetic diversity and the relationship among nine japonica rice groups consisting of 288 landraces and varieties in different geographical origins of Northeast Asia (China, Japan, Korea, Democratic People's Republic of Korea) and the Russian Far East district of the Russian Federation were evaluated with 154 simple sequence repeat (SSR) markers. A total of 823 alleles were detected. The observed allele numbers (Na) per locus, Nei's gene diversity (He) and the polymorphism information content (PIC) ranged from 2 to 9, 0.061 to 0.869 and 0.060 to 0.856, with an average of 5.344, 0.624 and 0.586, respectively. Five SSR loci, RM1350, RM1369, RM257, RM336 and RM1374, provided the highest PIC values and are potential for exploring the genetic diversity of rice cultivars in Northeast Asia. Molecular variance analysis showed that a significant difference existed both among groups (91.6%) and within each group (8.4%). The low genetic variation within each group indicated that the gene pool is narrow and alien genetic variation should be introduced into the rice breeding program in Northeast Asia. Based on the He and PIC values, the nine groups were ranked in a descending order: Heilongjiang landraces, Jilin landraces, Japanese improved varieties, Heilongjiang improved varieties, Russian Far East district of the Russian Federation improved varieties, Liaoning improved varieties, Jilin improved varieties, Korean improved varieties and Democratic People's Republic of Korea improved varieties. The nine groups were further divided into three subgroups and the 288 varieties into five clusters. This study provided information for parent selection in order to broaden the gene pool of the japonica rice germplasm in Northeast Asia. PMID:26019508

Genetic diversity and genetic relationships of japonica rice varieties in Northeast Asia based on SSR markers.

PubMed

Wang, Jingguo; Jiang, Tingbo; Zou, Detang; Zhao, Hongwei; Li, Qiang; Liu, Hualong; Zhou, Changjun

2014-03-04

Genetic diversity and the relationship among nine japonica rice groups consisting of 288 landraces and varieties in different geographical origins of Northeast Asia (China, Japan, Korea, Democratic People's Republic of Korea) and the Russian Far East district of the Russian Federation were evaluated with 154 simple sequence repeat (SSR) markers. A total of 823 alleles were detected. The observed allele numbers (Na) per locus, Nei's gene diversity (He) and the polymorphism information content (PIC) ranged from 2 to 9, 0.061 to 0.869 and 0.060 to 0.856, with an average of 5.344, 0.624 and 0.586, respectively. Five SSR loci, RM1350, RM1369, RM257, RM336 and RM1374, provided the highest PIC values and are potential for exploring the genetic diversity of rice cultivars in Northeast Asia. Molecular variance analysis showed that a significant difference existed both among groups (91.6%) and within each group (8.4%). The low genetic variation within each group indicated that the gene pool is narrow and alien genetic variation should be introduced into the rice breeding program in Northeast Asia. Based on the He and PIC values, the nine groups were ranked in a descending order: Heilongjiang landraces, Jilin landraces, Japanese improved varieties, Heilongjiang improved varieties, Russian Far East district of the Russian Federation improved varieties, Liaoning improved varieties, Jilin improved varieties, Korean improved varieties and Democratic People's Republic of Korea improved varieties. The nine groups were further divided into three subgroups and the 288 varieties into five clusters. This study provided information for parent selection in order to broaden the gene pool of the japonica rice germplasm in Northeast Asia.

Error correction and statistical analyses for intra-host comparisons of feline immunodeficiency virus diversity from high-throughput sequencing data.

PubMed

Liu, Yang; Chiaromonte, Francesca; Ross, Howard; Malhotra, Raunaq; Elleder, Daniel; Poss, Mary

2015-06-30

Infection with feline immunodeficiency virus (FIV) causes an immunosuppressive disease whose consequences are less severe if cats are co-infected with an attenuated FIV strain (PLV). We use virus diversity measurements, which reflect replication ability and the virus response to various conditions, to test whether diversity of virulent FIV in lymphoid tissues is altered in the presence of PLV. Our data consisted of the 3' half of the FIV genome from three tissues of animals infected with FIV alone, or with FIV and PLV, sequenced by 454 technology. Since rare variants dominate virus populations, we had to carefully distinguish sequence variation from errors due to experimental protocols and sequencing. We considered an exponential-normal convolution model used for background correction of microarray data, and modified it to formulate an error correction approach for minor allele frequencies derived from high-throughput sequencing. Similar to accounting for over-dispersion in counts, this accounts for error-inflated variability in frequencies - and quite effectively reproduces empirically observed distributions. After obtaining error-corrected minor allele frequencies, we applied ANalysis Of VAriance (ANOVA) based on a linear mixed model and found that conserved sites and transition frequencies in FIV genes differ among tissues of dual and single infected cats. Furthermore, analysis of minor allele frequencies at individual FIV genome sites revealed 242 sites significantly affected by infection status (dual vs. single) or infection status by tissue interaction. All together, our results demonstrated a decrease in FIV diversity in bone marrow in the presence of PLV. Importantly, these effects were weakened or undetectable when error correction was performed with other approaches (thresholding of minor allele frequencies; probabilistic clustering of reads). We also queried the data for cytidine deaminase activity on the viral genome, which causes an asymmetric increase

Complex and multi-allelic copy number variation in human disease

PubMed Central

McCarroll, Steven A.

2015-01-01

Hundreds of copy number variants are complex and multi-allelic, in that they have many structural alleles and have rearranged multiple times in the ancestors who contributed chromosomes to current humans. Not only are the relationships of these multi-allelic CNVs (mCNVs) to phenotypes generally unknown, but many mCNVs have not yet been described at the basic levels—alleles, allele frequencies, structural features—that support genetic investigation. To date, most reported disease associations to these variants have been ascertained through candidate gene studies. However, only a few associations have reached the level of acceptance defined by durable replications in many cohorts. This likely stems from longstanding challenges in making precise molecular measurements of the alleles individuals have at these loci. However, approaches for mCNV analysis are improving quickly, and some of the unique characteristics of mCNVs may assist future association studies. Their various structural alleles are likely to have different magnitudes of effect, creating a natural allelic series of growing phenotypic impact and giving investigators a set of natural predictions and testable hypotheses about the extent to which each allele of an mCNV predisposes to a phenotype. Also, mCNVs’ low-to-modest correlation to individual single-nucleotide polymorphisms (SNPs) may make it easier to distinguish between mCNVs and nearby SNPs as the drivers of an association signal, and perhaps, make it possible to preliminarily screen candidate loci, or the entire genome, for the many mCNV–disease relationships that remain to be discovered. PMID:26163405

Association of canine hypothyroidism with a common major histocompatibility complex DLA class II allele.

PubMed

Kennedy, L J; Quarmby, S; Happ, G M; Barnes, A; Ramsey, I K; Dixon, R M; Catchpole, B; Rusbridge, C; Graham, P A; Hillbertz, N S; Roethel, C; Dodds, W J; Carmichael, N G; Ollier, W E R

2006-07-01

Dogs exhibit a range of immune-mediated conditions including a lymphocytic thyroiditis which has many similarities to Hashimoto's thyroiditis in man. We have recently reported an association in Doberman Pinschers between canine hypothyroidism and a rare DLA class II haplotype that contains the DLA-DQA1*00101 allele. We now report a further series of 173 hypothyroid dogs in a range of breeds where a significant association with DLA-DQA1*00101 is shown.

High diversity and no significant selection signal of human ADH1B gene in Tibet

PubMed Central

2012-01-01

Background ADH1B is one of the most studied human genes with many polymorphic sites. One of the single nucleotide polymorphism (SNP), rs1229984, coding for the Arg48His substitution, have been associated with many serious diseases including alcoholism and cancers of the digestive system. The derived allele, ADH1B*48His, reaches high frequency only in East Asia and Southwest Asia, and is highly associated with agriculture. Micro-evolutionary study has defined seven haplogroups for ADH1B based on seven SNPs encompassing the gene. Three of those haplogroups, H5, H6, and H7, contain the ADH1B*48His allele. H5 occurs in Southwest Asia and the other two are found in East Asia. H7 is derived from H6 by the derived allele of rs3811801. The H7 haplotype has been shown to have undergone significant positive selection in Han Chinese, Hmong, Koreans, Japanese, Khazak, Mongols, and so on. Methods In the present study, we tested whether Tibetans also showed evidence for selection by typing 23 SNPs in the region covering the ADH1B gene in 1,175 individuals from 12 Tibetan populations representing all districts of the Tibet Autonomous Region. Multiple statistics were estimated to examine the gene diversities and positive selection signals among the Tibetans and other populations in East Asia. Results The larger Tibetan populations (Qamdo, Lhasa, Nagqu, Nyingchi, Shannan, and Shigatse) comprised mostly farmers, have around 12% of H7, and 2% of H6. The smaller populations, living on hunting or recently switched to farming, have lower H7 frequencies (Tingri 9%, Gongbo 8%, Monba and Sherpa 6%). Luoba (2%) and Deng (0%) have even lower frequencies. Long-range haplotype analyses revealed very weak signals of positive selection for H7 among Tibetans. Interestingly, the haplotype diversity of H7 is higher in Tibetans than in any other populations studied, indicating a longer diversification history for that haplogroup in Tibetans. Network analysis on the long-range haplotypes revealed

Determination of multiple-clone infection at allelic dimorphism site of Plasmodium vivax merozoite surface protein-1 in the Republic of Korea by pyrosequencing assay.

PubMed

Dinzouna-Boutamba, Sylvatrie-Danne; Lee, Sanghyun; Son, Ui-Han; Yun, Hae Soo; Joo, So-Young; Jeong, Sookwan; Rhee, Man Hee; Kwak, Dongmi; Xuan, Xuenan; Hong, Yeonchul; Chung, Dong-Il; Goo, Youn-Kyoung

2017-12-01

Allelic diversity leading to multiple gene polymorphisms of vivax malaria parasites has been shown to greatly contribute to antigenic variation and drug resistance, increasing the potential for multiple-clone infections within the host. Therefore, to identify multiple-clone infections and the predominant haplotype of Plasmodium vivax in a South Korean population, P. vivax merozoite surface protein-1 (PvMSP-1) was analyzed by pyrosequencing. Pyrosequencing of 156 vivax malaria-infected samples yielded 97 (62.18%) output pyrograms showing two main types of peak patterns of the dimorphic allele for threonine and alanine (T1476A). Most of the samples evaluated (88.66%) carried multiple-clone infections (wild- and mutant-types), whereas 11.34% of the same population carried only the mutant-type (1476A). In addition, each allele showed a high frequency of guanine (G) base substitution at both the first and third positions (86.07% and 81.13%, respectively) of the nucleotide combinations. Pyrosequencing of the PvMSP-1 42-kDa fragment revealed a heterogeneous parasite population, with the mutant-type dominant compared to the wild-type. Understanding the genetic diversity and multiple-clone infection rates may lead to improvements in vivax malaria prevention and strategic control plans. Further studies are needed to improve the efficacy of the pyrosequencing assay with large sample sizes and additional nucleotide positions. Copyright © 2017 Elsevier B.V. All rights reserved.

Reduced Height (Rht) Alleles Affect Wheat Grain Quality

PubMed Central

Casebow, Richard; Hadley, Caroline; Uppal, Rajneet; Addisu, Molla; Loddo, Stefano; Kowalski, Ania; Griffiths, Simon; Gooding, Mike

2016-01-01

The effects of dwarfing alleles (reduced height, Rht) in near isogenic lines on wheat grain quality are characterised in field experiments and related to effects on crop height, grain yield and GA-sensitivity. Alleles included those that conferred GA-insensitivity (Rht-B1b, Rht-B1c, Rht-D1b, Rht-D1c) as well as those that retained GA-sensitivity (rht(tall), Rht8, Rht8 + Ppd-D1a, Rht12). Full characterisation was facilitated by including factors with which the effects of Rht alleles are known to interact for grain yield (i.e. system, [conventional or organic]; tillage intensity [plough-based, minimum or zero]; nitrogen fertilizer level [0–450 kg N/ha]; and genetic backgrounds varying in height [cvs Maris Huntsman, Maris Widgeon, and Mercia]. Allele effects on mean grain weight and grain specific weight were positively associated with final crop height: dwarfing reduced these quality criteria irrespective of crop management or GA-sensitivity. In all but two experiments the effects of dwarfing alleles on grain nitrogen and sulphur concentrations were closely and negatively related to effects on grain yield, e.g. a quadratic relationship between grain yield and crop height manipulated by the GA-insensitive alleles was mirrored by quadratic relationships for nitrogen and sulphur concentrations: the highest yields and most dilute concentrations occurred around 80cm. In one of the two exceptional experiments the GA-insensitive Rht-B1b and Rht-B1c significantly (P<0.05) reduced grain nitrogen concentration in the absence of an effect on yield, and in the remaining experiment the GA-sensitive Rht8 significantly reduced both grain yield and grain nitrogen concentration simultaneously. When Rht alleles diluted grain nitrogen concentration, N:S ratios and SDS-sedimentation volumes were often improved. Hagberg falling number (HFN) was negatively related to crop height but benefits from dwarfing were only seen for GA-insensitive alleles. For HFN, therefore, there was the

Effects of historical climate change, habitat connectivity, and vicariance on genetic structure and diversity across the range of the Red Tree Vole (Phenacomys longicaudus) in the Pacific Northwest United States

USGS Publications Warehouse

Miller, Mark P.; Bellinger, R.M.; Forsman, E.D.; Haig, Susan M.

2006-01-01

Phylogeographical analyses conducted in the Pacific Northwestern United States have often revealed concordant patterns of genetic diversity among taxa. These studies demonstrate distinct North/South genetic discontinuities that have been attributed to Pleistocene glaciation. We examined phylogeographical patterns of red tree voles (Phenacomys longicaudus) in western Oregon by analysing mitochondrial control region sequences for 169 individuals from 18 areas across the species' range. Cytochrome b sequences were also analysed from a subset of our samples to confirm the presence of major haplotype groups. Phylogenetic network analyses suggested the presence of two haplotype groups corresponding to northern and southern regions of P. longicaudus' range. Spatial genetic analyses (samova and Genetic Landscape Shapes) of control region sequences demonstrated a primary genetic discontinuity separating northern and southern sampling areas, while a secondary discontinuity separated northern sampling areas into eastern and western groups divided by the Willamette Valley. The North/South discontinuity likely corresponds to a region of secondary contact between lineages rather than an overt barrier. Although the Cordilleran ice sheet (maximum a??12 000 years ago) did not move southward to directly affect the region occupied by P. longicaudus, climate change during glaciation fragmented the forest landscape that it inhabits. Signatures of historical fragmentation were reflected by positive associations between latitude and variables such as Tajima's D and patterns associated with location-specific alleles. Genetic distances between southern sampling areas were smaller, suggesting that forest fragmentation was reduced in southern vs. northern regions.

Patterns of genetic diversity and candidate genes for ecological divergence in a homoploid hybrid sunflower, Helianthus anomalus

PubMed Central

SAPIR, YUVAL; MOODY, MICHAEL L.; BROUILLETTE, LARRY C.; DONOVAN, LISA A.; RIESEBERG, LOREN H.

2008-01-01

Natural hybridization accompanied by a shift in niche preference by hybrid genotypes can lead to hybrid speciation. Natural selection may cause the fixation of advantageous alleles in the ecologically diverged hybrids, and the loci experiencing selection should exhibit a reduction in allelic diversity relative to neutral loci. Here, we analyzed patterns of genetic diversity at 59 microsatellite loci associated with expressed sequence tags (ESTs) in a homoploid hybrid sunflower species, Helianthus anomalus. We used two indices, ln RV and ln RH, to compare variation and heterozygosity (respectively) at each locus between the hybrid species and its two parental species, H. annuus and H. petiolaris. Mean values of ln RV and ln RH were significantly lower than zero, which implies that H. anomalus experienced a population bottleneck during its recent evolutionary history. After correcting for the apparent bottleneck, we found six loci with a significant reduction in variation or with heterozygosity in the hybrid species, compared to one or both of the parental species. These loci should be viewed as a ranked list of candidate loci, pending further sequencing and functional analyses. Sequence data were generated for two of the candidate loci, but population genetics tests failed to detect deviations from neutral evolution at either locus. Nonetheless, a greater than eight-fold excess of nonsynonymous substitutions was found near a putative N-myristoylation motif at the second locus (HT998), and likelihood-based models indicated that the protein has been under selection in H. anomalus in the past and, perhaps, in one or both parental species. Finally, our data suggest that selective sweeps may have united populations of H. anomalus isolated by a mountain range, indicating that even low gene-flow species may be held together by the spread of advantageous alleles. PMID:17944850

Genetic Diversity and Ecological Niche Modelling of Wild Barley: Refugia, Large-Scale Post-LGM Range Expansion and Limited Mid-Future Climate Threats?

PubMed Central

Russell, Joanne; van Zonneveld, Maarten; Dawson, Ian K.; Booth, Allan; Waugh, Robbie; Steffenson, Brian

2014-01-01

Describing genetic diversity in wild barley (Hordeum vulgare ssp. spontaneum) in geographic and environmental space in the context of current, past and potential future climates is important for conservation and for breeding the domesticated crop (Hordeum vulgare ssp. vulgare). Spatial genetic diversity in wild barley was revealed by both nuclear- (2,505 SNP, 24 nSSR) and chloroplast-derived (5 cpSSR) markers in 256 widely-sampled geo-referenced accessions. Results were compared with MaxEnt-modelled geographic distributions under current, past (Last Glacial Maximum, LGM) and mid-term future (anthropogenic scenario A2, the 2080s) climates. Comparisons suggest large-scale post-LGM range expansion in Central Asia and relatively small, but statistically significant, reductions in range-wide genetic diversity under future climate. Our analyses support the utility of ecological niche modelling for locating genetic diversity hotspots and determine priority geographic areas for wild barley conservation under anthropogenic climate change. Similar research on other cereal crop progenitors could play an important role in tailoring conservation and crop improvement strategies to support future human food security. PMID:24505252

Genetic diversity analysis among collected purslane (Portulaca oleracea L.) accessions using ISSR markers.

PubMed

Alam, M Amirul; Juraimi, Abdul Shukor; Rafii, Mohd Yusop; Hamid, Azizah Abdul; Arolu, Ibrahim Wasiu; Abdul Latif, M

2015-01-01

Genetic diversity and relationships among 45 collected purslane accessions were evaluated using ISSR markers. The 28 primers gave a total of 167 bands, among which 163 were polymorphic (97.6%). The genetic diversity as estimated by Shannon's information index was 0.513, revealing a quite high level of genetic diversity in the germplasm. The average number of observed allele, effective allele, expected heterozygosity, polymorphic information content (PIC) and Nei's index were 5.96, 1.59, 0.43, 0.35 and 0.35, respectively. The UPGMA dendrogram based on Nei's genetic distance grouped the whole germplasm into 7 distinct clusters. The analysis of molecular variance (AMOVA) revealed that 89% of total variation occurred within population, while 11% were found among populations. Based on the constructed dendrogram using ISSR markers those accessions that are far from each other by virtue of genetic origin and diversity index (like Ac1 and Ac42; Ac19 and Ac45; Ac9 and Ac23; Ac18 and A25; Ac24 and Ac18) are strongly recommended to select as parent for future breeding program to develop high yielding and stress tolerant purslane variety in contribution to global food security. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Allelic variants of hereditary prions: The bimodularity principle

PubMed Central

Tikhodeyev, Oleg N.; Tarasov, Oleg V.; Bondarev, Stanislav A.

2017-01-01

ABSTRACT Modern biology requires modern genetic concepts equally valid for all discovered mechanisms of inheritance, either “canonical” (mediated by DNA sequences) or epigenetic. Applying basic genetic terms such as “gene” and “allele” to protein hereditary factors is one of the necessary steps toward these concepts. The basic idea that different variants of the same prion protein can be considered as alleles has been previously proposed by Chernoff and Tuite. In this paper, the notion of prion allele is further developed. We propose the idea that any prion allele is a bimodular hereditary system that depends on a certain DNA sequence (DNA determinant) and a certain epigenetic mark (epigenetic determinant). Alteration of any of these 2 determinants may lead to establishment of a new prion allele. The bimodularity principle is valid not only for hereditary prions; it seems to be universal for any epigenetic hereditary factor. PMID:28281926

Global sequence diversity of the lactate dehydrogenase gene in Plasmodium falciparum.

PubMed

Simpalipan, Phumin; Pattaradilokrat, Sittiporn; Harnyuttanakorn, Pongchai

2018-01-09

Antigen-detecting rapid diagnostic tests (RDTs) have been recommended by the World Health Organization for use in remote areas to improve malaria case management. Lactate dehydrogenase (LDH) of Plasmodium falciparum is one of the main parasite antigens employed by various commercial RDTs. It has been hypothesized that the poor detection of LDH-based RDTs is attributed in part to the sequence diversity of the gene. To test this, the present study aimed to investigate the genetic diversity of the P. falciparum ldh gene in Thailand and to construct the map of LDH sequence diversity in P. falciparum populations worldwide. The ldh gene was sequenced for 50 P. falciparum isolates in Thailand and compared with hundreds of sequences from P. falciparum populations worldwide. Several indices of molecular variation were calculated, including the proportion of polymorphic sites, the average nucleotide diversity index (π), and the haplotype diversity index (H). Tests of positive selection and neutrality tests were performed to determine signatures of natural selection on the gene. Mean genetic distance within and between species of Plasmodium ldh was analysed to infer evolutionary relationships. Nucleotide sequences of P. falciparum ldh could be classified into 9 alleles, encoding 5 isoforms of LDH. L1a was the most common allelic type and was distributed in P. falciparum populations worldwide. Plasmodium falciparum ldh sequences were highly conserved, with haplotype and nucleotide diversity values of 0.203 and 0.0004, respectively. The extremely low genetic diversity was maintained by purifying selection, likely due to functional constraints. Phylogenetic analysis inferred the close genetic relationship of P. falciparum to malaria parasites of great apes, rather than to other human malaria parasites. This study revealed the global genetic variation of the ldh gene in P. falciparum, providing knowledge for improving detection of LDH-based RDTs and supporting the candidacy of

Genetic Diversity of Plasmodium falciparum in Haiti: Insights from Microsatellite Markers

PubMed Central

Carter, Tamar E.; Malloy, Halley; Existe, Alexandre; Memnon, Gladys; St. Victor, Yves; Okech, Bernard A.; Mulligan, Connie J.

2015-01-01

Hispaniola, comprising Haiti and the Dominican Republic, has been identified as a candidate for malaria elimination. However, incomplete surveillance data in Haiti hamper efforts to assess the impact of ongoing malaria control interventions. Characteristics of the genetic diversity of Plasmodium falciparum populations can be used to assess parasite transmission, which is information vital to evaluating malaria elimination efforts. Here we characterize the genetic diversity of P. falciparum samples collected from patients at seven sites in Haiti using 12 microsatellite markers previously employed in population genetic analyses of global P. falciparum populations. We measured multiplicity of infections, level of genetic diversity, degree of population geographic substructure, and linkage disequilibrium (defined as non-random association of alleles from different loci). For low transmission populations like Haiti, we expect to see few multiple infections, low levels of genetic diversity, high degree of population structure, and high linkage disequilibrium. In Haiti, we found low levels of multiple infections (12.9%), moderate to high levels of genetic diversity (mean number of alleles per locus = 4.9, heterozygosity = 0.61), low levels of population structure (highest pairwise Fst = 0.09 and no clustering in principal components analysis), and moderate linkage disequilibrium (ISA = 0.05, P<0.0001). In addition, population bottleneck analysis revealed no evidence for a reduction in the P. falciparum population size in Haiti. We conclude that the high level of genetic diversity and lack of evidence for a population bottleneck may suggest that Haiti’s P. falciparum population has been stable and discuss the implications of our results for understanding the impact of malaria control interventions. We also discuss the relevance of parasite population history and other host and vector factors when assessing transmission intensity from genetic diversity data. PMID:26462203

Allelic variation in PtoPsbW associated with photosynthesis, growth, and wood properties in Populus tomentosa.

PubMed

Wang, Longxin; Wang, Bowen; Du, Qingzhang; Chen, Jinhui; Tian, Jiaxing; Yang, Xiaohui; Zhang, Deqiang

2017-02-01

Photosynthesis is one of the most important reactions on earth. PsbW, a nuclear-encoded subunit of photosystem II (PSII), stabilizes PSII structure and plays an important role in photosynthesis. Here, we used candidate gene-based linkage disequilibrium (LD) mapping to detect significant associations between allelic variations of PtoPsbW and traits related to photosynthesis, growth, and wood properties in Populus tomentosa. PtoPsbW showed the highest expression in leaves and it increased during the development of these leaves, suggesting that PtoPsbW may play an important role in plant growth and development. Analysis of nucleotide diversity and LD revealed that PtoPsbW has low single-nucleotide polymorphism (SNP) diversity (π tot  = 0.0048 and θ w  = 0.0050) and relatively low average value of LD (0.1500), indicating that PtoPsbW is conserved due to its indispensable function. Using single-SNP associations in an association population of 435 individuals, we identified five significant associations at the threshold of P ≤ 0.05, explaining 3.28-15.98 % of the phenotypic variation. Haplotype-based association analyses indicated that 13 haplotypes (P ≤ 0.05) from six blocks were associated with photosynthesis, growth, and wood properties. Our work shows that identifying allelic variation and LD can help to decipher the genetic basis of photosynthesis and could potentially be applied for molecular marker-assisted selection in Populus.

Spatial variation and low diversity in the major histocompatibility complex in walrus (Odobenus rosmarus)

USGS Publications Warehouse

Sonsthagen, Sarah A.; Fales, Krystal R.; Jay, Chadwick V.; Sage, George K.; Talbot, Sandra L.

2014-01-01

Increased global temperature and associated changes to Arctic habitats will likely result in the northward advance of species, including an influx of pathogens novel to the Arctic. How species respond to these immunological challenges will depend in part on the adaptive potential of their immune response system. We compared levels of genetic diversity at a gene associated with adaptive immune response [Class II major histocompatibility complex (MHC), DQB exon 2] between populations of walrus (Odobenus rosmarus), a sea ice-dependent Arctic species. Walrus was represented by only five MHC DQB alleles, with frequency differences observed between Pacific and Atlantic populations. MHC DQB alleles appear to be under balancing selection, and most (80 %; n = 4/5) of the alleles were observed in walruses from both oceans, suggesting broad scale differences in the frequency of exposure and diversity of pathogens may be influencing levels of heterozygosity at DQB in walruses. Limited genetic diversity at MHC, however, suggests that walrus may have a reduced capacity to respond to novel immunological challenges associated with shifts in ecological communities and environmental stressors predicted for changing climates. This is particularly pertinent for walrus, since reductions in summer sea ice may facilitate both northward expansion of marine species and associated pathogens from more temperate regions, and exchange of marine mammals and associated pathogens through the recently opened Northwest Passage between the Atlantic and Pacific Oceans in the Canadian high Arctic.

Heterospecific SNP diversity in humans and rhesus macaque (Macaca mulatta)

PubMed Central

Ng, Jillian; Trask, Jessica Satkoski; Smith, David Glenn; Kanthaswamy, Sree

2018-01-01

Background Conservation of single nucleotide polymorphisms (SNPs) between human and other primates (i.e., heterospecific SNPs) in candidate genes can be used to assess the utility of those organisms as models for human biomedical research. Methods 59,691 heterospecific SNPs in 22 rhesus macaques and 20 humans were analyzed for human trait associations and 4,207 heterospecific SNPs biallelic in both taxa were compared for genetic variation. Results Variation comparisons at the 4,207 SNPs showed that humans were more genetically diverse than rhesus macaques with observed and expected heterozygosities of 0.337 and 0.323 versus 0.119 and 0.102, and minor allele frequencies of 0.239 and 0.063, respectively. 431 of the 59,691 heterospecific SNPs are reportedly associated with human-specific traits. Conclusion While comparisons between human and rhesus macaque genomes are plausible, functional studies of heterospecific SNPs are necessary to determine whether rhesus macaque alleles are associated with the same phenotypes as their corresponding human alleles. PMID:25963897

An allele of an ancestral transcription factor dependent on a horizontally acquired gene product.

PubMed

Chen, H Deborah; Jewett, Mollie W; Groisman, Eduardo A

2012-01-01

Changes in gene regulatory circuits often give rise to phenotypic differences among closely related organisms. In bacteria, these changes can result from alterations in the ancestral genome and/or be brought about by genes acquired by horizontal transfer. Here, we identify an allele of the ancestral transcription factor PmrA that requires the horizontally acquired pmrD gene product to promote gene expression. We determined that a single amino acid difference between the PmrA proteins from the human adapted Salmonella enterica serovar Paratyphi B and the broad host range S. enterica serovar Typhimurium rendered transcription of PmrA-activated genes dependent on the PmrD protein in the former but not the latter serovar. Bacteria harboring the serovar Typhimurium allele exhibited polymyxin B resistance under PmrA- or under PmrA- and PmrD-inducing conditions. By contrast, isogenic strains with the serovar Paratyphi B allele displayed PmrA-regulated polymyxin B resistance only when experiencing activating conditions for both PmrA and PmrD. We establish that the two PmrA orthologs display quantitative differences in several biochemical properties. Strains harboring the serovar Paratyphi B allele showed enhanced biofilm formation, a property that might promote serovar Paratyphi B's chronic infection of the gallbladder. Our findings illustrate how subtle differences in ancestral genes can impact the ability of horizontally acquired genes to confer new properties.

Genetic diversity of Plasmodium Vivax revealed by the merozoite surface protein-1 icb5-6 fragment.

PubMed

Ruan, Wei; Zhang, Ling-Ling; Feng, Yan; Zhang, Xuan; Chen, Hua-Liang; Lu, Qiao-Yi; Yao, Li-Nong; Hu, Wei

2017-06-05

Plasmodium vivax remains a potential cause of morbidity and mortality for people living in its endemic areas. Understanding the genetic diversity of P. vivax from different regions is valuable for studying population dynamics and tracing the origins of parasites. The PvMSP-1 gene is highly polymorphic and has been used as a marker in many P. vivax population studies. The aim of this study was to investigate the genetic diversity of the PvMSP-1 gene icb5-6 fragment and to provide more genetic polymorphism data for further studies on P. vivax population structure and tracking of the origin of clinical cases. Nested PCR and sequencing of the PvMSP-1 icb5-6 marker were performed to obtain the nucleotide sequences of 95 P. vivax isolates collected from Zhejiang province, China. To investigate the genetic diversity of PvMSP-1, the 95 nucleotide sequences of the PvMSP-1 icb5-6 fragment were genotyped and analyzed using DnaSP v5, MEGA software. The 95 P. vivax isolates collected from Zhejiang province were either indigenous cases or imported cases from different regions around the world. A total of 95 sequences ranging from 390 to 460 bp were obtained. The 95 sequences were genotyped into four allele-types (Sal I, Belem, R-III and R-IV) and 17 unique haplotypes. R-III and Sal I were the predominant allele-types. The haplotype diversity (Hd) and nucleotide diversity (Pi) were estimated to be 0.729 and 0.062, indicating that the PvMSP-1 icb5-6 fragment had the highest level of polymorphism due to frequent recombination processes and single nucleotide polymorphism. The values of dN/dS and Tajima's D both suggested neutral selection for the PvMSP-1icb5-6 fragment. In addition, a rare recombinant style of R-IV type was identified. This study presented high genetic diversity in the PvMSP-1 marker among P. vivax strains from around the world. The genetic data is valuable for expanding the polymorphism information on P. vivax, which could be helpful for further study on

PATTERNS OF ALLOZYME DIVERSITY IN THE THREATENED PLANT ERIGERON PARISHII (ASTERACEAE). (R826102)

EPA Science Inventory

Thirty-one occurrences of Erigeron parishii, a narrowly endemic plant threatened by mining, were sampled for allozyme diversity. This taxon held considerable genetic variation at the [4 allozyme loci surveyed. Species (e.g., alleles per locus [A] = 4.3 and proportion of polymorph...

Genetic Diversity of Spanish Melons (Cucumis melo L.) of the Madrid Provenance

USDA-ARS?s Scientific Manuscript database

The genetic diversity of five Group Inodorus landraces having a historic presence in the town of Villaconejos, Spain (near Madrid) and four reference accessions (one accession Group Flexuosus) (Lopez-Sese et al, 2002), was assessed using the allelic variation at 19 SSR loci. Seventy-two polymorphic...

Spatio-temporal variation in parasite communities maintains diversity at the major histocompatibility complex class IIβ in the endangered Rio Grande silvery minnow.

PubMed

Osborne, Megan J; Pilger, Tyler J; Lusk, Joel D; Turner, Thomas F

2017-01-01

Climate change will strongly impact aquatic ecosystems particularly in arid and semi-arid regions. Fish-parasite interactions will also be affected by predicted altered flow and temperature regimes, and other environmental stressors. Hence, identifying environmental and genetic factors associated with maintaining diversity at immune genes is critical for understanding species' adaptive capacity. Here, we combine genetic (MHC class IIβ and microsatellites), parasitological and ecological data to explore the relationship between these factors in the remnant wild Rio Grande silvery minnow (Hybognathus amarus) population, an endangered species found in the southwestern United States. Infections with multiple parasites on the gills were observed and there was spatio-temporal variation in parasite communities and patterns of infection among individuals. Despite its highly endangered status and chronically low genetic effective size, Rio Grande silvery minnow had high allelic diversity at MHC class IIβ with more alleles recognized at the presumptive DAB1 locus compared to the DAB3 locus. We identified significant associations between specific parasites and MHC alleles against a backdrop of generalist parasite prevalence. We also found that individuals with higher individual neutral heterozygosity and higher amino acid divergence between MHC alleles had lower parasite abundance and diversity. Taken together, these results suggest a role for fluctuating selection imposed by spatio-temporal variation in pathogen communities and divergent allele advantage in maintenance of high MHC polymorphism. Understanding the complex interaction of habitat, pathogens and immunity in protected species will require integrated experimental, genetic and field studies. © 2016 John Wiley & Sons Ltd.

Comparative analysis of microsatellites in five different antagonistic Trichoderma species for diversity assessment.

PubMed

Rai, Shalini; Kashyap, Prem Lal; Kumar, Sudheer; Srivastava, Alok Kumar; Ramteke, Pramod W

2016-01-01

Microsatellites provide an ideal molecular markers system to screen, characterize and evaluate genetic diversity of several fungal species. Currently, there is very limited information on the genetic diversity of antagonistic Trichoderma species as determined using a range of molecular markers. In this study, expressed and whole genome sequences available in public database were used to investigate the occurrence, relative abundance and relative density of SSRs in five different antagonistic Trichoderma species: Trichoderma atroviride, T. harzianum, T. reesei, T. virens and T. asperellum. Fifteen SSRs loci were used to evaluate genetic diversity of twenty isolates of Trichoderma spp. from different geographical regions of India. Results indicated that relative abundance and relative density of SSRs were higher in T. asperellum followed by T. reesei and T. atroviride. Tri-nucleotide repeats (80.2%) were invariably the most abundant in all species. The abundance and relative density of SSRs were not influenced by the genome sizes and GC content. Out of eighteen primer sets, only 15 primer pairs showed successful amplification in all the test species. A total of 24 alleles were detected and five loci were highly informative with polymorphism information content values greater than 0.40, these markers provide useful information on genetic diversity and population genetic structure, which, in turn, can exploit for establishing conservation strategy for antagonistic Trichoderma isolates.

[Evaluation of Molecular Genetic Diversity of Wild Apple Malus sieversii Populations from Zailiysky Alatau by Microsatellite Markers].

PubMed

Omasheva, M E; Chekalin, S V; Galiakparov, N N

2015-07-01

The territory of Kazakhstan is part of the distribution range of Malus sieversii, which is one of the ancestors of cultivated apple tree varieties. The collected samples of Sievers apple leaves from five populations growing in the Zailiysky Alatau region served as a source not only for the creation of a bank of genomic DNA but also for determination ofthe wild apple genetic polymorphism. The seven microsatellite markers used in this study revealed 86 alleles with different frequencies, as well as the characteristic pools of rare alleles for each of the populations. Molecular genetic analysis showed a high level of genetic diversity (H(o) = 0.704; PIC = 0.752; I = 1.617). Moreover, interpopulation variability accounted only for 7.5% of total variability, confirming the genetic closeness of the populations examined. Based on phylogenetic analysis, it was demonstrated that the Bel'bulak and Almaty Reserve populations were closest to each other, while the most distant were the Ketmen and Great Almaty gorge populations, which suggests the dependence of genetic distance on the geographical.

Cytochrome P450 2D6 variants in a Caucasian population: Allele frequencies and phenotypic consequences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sachse, C.; Brockmoeller, J.; Bauer, S.

Cytochrome P450 2D6 (CYP2D6) metabolizes many important drugs. CYP2D6 activity ranges from complete deficiency to ultrafast metabolism, depending on at least 16 different known alleles. Their frequencies were determined in 589 unrelated German volunteers and correlated with enzyme activity measured by phenotyping with dextromethorphan or debrisoquine. For genotyping, nested PCR-RFLP tests from a PCR amplificate of the entire CYP2D6 gene were developed. The frequency of the CYP2D6*1 allele coding for extensive metabolizer (EM) phenotype was .364. The alleles coding for slightly (CYP2D6*2) or moderately (*9 and *10) reduced activity (intermediate metabolizer phenotype [IM]) showed frequencies of .324, .018, and .015,more » respectively. By use of novel PCR tests for discrimination, CYP2D6 gene duplication alleles were found with frequencies of.005 (*1 x 2), .013 (* 2 x 2), and .001 (*4 x 2). Frequencies of alleles with complete deficiency (poor metabolizer phenotype [PM]) were .207 (*4), .020 (*3 and *5), .009 (*6), and .001 (*7, *15, and *16). The defective CYP2D6 alleles *8, *11, *12, *13, and *14 were not found. All 41 PMs (7.0%) in this sample were explained by five mutations detected by four PCR-RFLP tests, which may suffice, together with the gene duplication test, for clinical prediction of CYP2D6 capacity. Three novel variants of known CYP2D6 alleles were discovered: *1C (T{sub 1957}C), *2B (additional C{sub 2558}T), and *4E (additional C{sub 2938}T). Analysis of variance showed significant differences in enzymatic activity measured by the dextromethorphan metabolic ratio (MR) between carriers of EN/PM (mean MR = .006) and IM/PM (mean MR = .014) alleles and between carriers of one (mean MR = .009) and two (mean MR = .003) functional alleles. The results of this study provide a solid basis for prediction of CYP2D6 capacity, as required in drug research and routine drug treatment. 35 refs., 4 figs., 5 tabs.« less

Diversity of Pneumolysin and Pneumococcal Histidine Triad Protein D of Streptococcus pneumoniae Isolated from Invasive Diseases in Korean Children.

PubMed

Yun, Ki Wook; Lee, Hyunju; Choi, Eun Hwa; Lee, Hoan Jong

2015-01-01

Pneumolysin (Ply) and pneumococcal histidine triad protein D (PhtD) are candidate proteins for a next-generation pneumococcal vaccine. We aimed to analyze the genetic diversity and antigenic heterogeneity of Ply and PhtD for 173 pneumococci isolated from invasive diseases in Korean children. Allele was designated based on the variation of amino acid sequence. Antigenicity was predicted by the amino acid hydrophobicity of the region. There were seven and 39 allele types for the ply and phtD genes, respectively. The nucleotide sequence identity was 97.2%-99.9% for ply and 91.4%-98.0% for phtD gene. Only minor variations in hydrophobicity were noted among the antigenicity plots of Ply and PhtD. Overall, the allele types of the ply and phtD genes were remarkably homogeneous, and the antigenic diversity of the corresponding proteins was very limited. The Ply and PhtD could be useful antigens for universal pneumococcal vaccines.