Distribution Of Haplotypes Research Articles

Redescription and molecular analysis of Corynosoma pseudohamanni Zdzitowiecki, 1984 (Acanthocephala: Polymorphidae) juveniles from Notothenia coriiceps Richardson in the water area of Argentine Islands, West Antarctica.

Corynosoma pseudohamanni Zdzitowiecki, 1984 (Polymorphidae) was described from the intestinal tract of 5 species of seals including the type and main host, the Weddell seal Leptonycotes weddellii (Lesson) in the South Shetlands, West Antarctica. Notothenia coriiceps was the primary paratenic host of 14 fish hosts reported in the original description. We describe excysted juveniles from the body cavity of the major paratenic host, Notothenia coriiceps Richardson collected off Galindez Island, Argentine Islands, West Antarctica for the first time. The original description was not "based on material collected from the final hosts (seals) and paratenic hosts (fish)" as stated since no description of juveniles was given then. Our excysted juveniles were generally smaller than reported adults and many of the other measurements were comparable to those of the adults in the original description. We added many of the incomplete measurements of adults in the original description especially those of the underdeveloped reproductive structures. We compared our morphometric description with the only other one available for juveniles collected from three paratenic fish hosts from Prince Gustav Channel, Antarctica. We have added informative optical microscopy images and SEM images of internal and external structures, previously missed in the original description. Energy Dispersive X-ray analysis revealed the highest levels of calcium in all hooks and hook roots compared to sulfur and phosphorus. We also provide a molecular characterization of the species for the first time. Newly generated sequences of the mitochondrial cytochrome c oxidase subunit 1 (mtcox1) gene from isolates of C. pseudohamanni cystacanths were compared with sequences of other acanthocephalans available in GenBank. Phylogenetic analyses based on maximum likelihood (ML) and Bayesian inference (BI) methods of the cox1 dataset placed all the species of Corynosoma in a single clade, with strong support. The mt cox1 sequences of C. pseudohamanni formed a strongly supported individual clade with the published sequences of Corynosoma nortmeri and Corynosoma magdaleni from the North Sea, Germany. We have determined the genetic diversity ofC. pseudohamanni and compare it with other Corynosoma species haplotype diversity and distribution.

Genetic diversity and phylogeography of the circumboreal peatland violets (Viola epipsila‐V. palustris complex, Violaceae) as inferred from non‐coding nuclear and chloroplast DNA regions

AbstractThe Pleistocene glaciation cycles are a major factor shaping plant genetic diversity, speciation and radiations, and current distribution ranges in the Northern Hemisphere. Case studies are important for improving our understanding of postglacial migration patterns in the Northern Hemisphere taxa in general. Here, we studied the circumboreal Viola epipsila‐V. palustris complex, whose taxonomy and patterns of variation are unclear, and phylogeography unknown, using non‐coding nuclear (ISSRs; inter simple sequence repeats) and chloroplast (cpDNA; trnS‐trnG and trnH‐psbA spacers) DNA regions. Our ISSR results separated five groups corresponding to V. epipsila, V. palustris, V. pluviae, V. suecica and hybrids (V. epipsila × V. palustris). These groups were also confirmed by the genome size of selected samples from each group. The ISSR results showed low within‐population genetic variation in V. epipsila, V. palustris, and V. pluviae as compared to V. suecica, which also has the widest distribution. The cpDNA data allowed us to infer postglacial migration routes and historical impact of gene flow between populations. A total of 13 haplotypes were identified across all species, with the largest number (eight) in European‐eastern Asian‐North American V. suecica. Five haplotypes were present in more than one taxon of the group. The low haplotype variation of European V. epipsila and V. palustris results from their status as glacial relicts. The cpDNA and ISSR phylogenies were congruent. The pattern of haplotype variation and distribution in the ranges of studied species indicates postglacial intercontinental migration of V. suecica across Beringia and V. palustris across the Atlantic.

Persistence of Ancestral KhoeSan Mitochondrial Patterns in Contemporary South African Populations.

Southern Africa has been inhabited by hunter-gatherers for at least 20,000 years and has received diverse immigration flows in the last 2000 years. The original inhabitants have interacted with the pastoralist migrants from Eastern Africa (∼2000 ybp), followed by the southern Bantu migration arriving some 1000 ybp, and more recently with the European and Asian settlers after the 17th century. Many of the original Khoekhoe and San inhabitants have either become extinct or have disappeared through admixture in South Africa (SA), in a sex-biased manner involving KhoeSan women. In this study, we generated mitochondrial DNA (mtDNA) control region (CR) sequences for 247 South African individuals. The sampling effort was concentrated in regions and populations with historical links to the KhoeSan population groups: admixed (Coloured, Griqua), Nama (Khoekhoe) and Bantu in three provinces. Here we evaluate the composition and extent of connectivity between population groups and regions, and to assess the distribution of haplotypes for the practical application of mtDNA CR data in forensic identifications. The analysis of the newly generated sequences revealed 142 distinct haplotypes, of which 122 were unique. Haplogroup L0 was predominant (overall 71.7%). A high-frequency L0d2a haplotype dominated the pool of the admixed groups with 10%-12.5% incidence overall or per region. Comparative analysis with 545 extant mtDNA CR sequences from South African KhoeSan and admixed descendants revealed extensive population structure and high within-group haplotype sharing. The observed population and regional variations, combined with the prevalence of high-frequency haplotypes, align with patterns of matrilocality. These findings highlight the limitations of using mtDNA control region analysis for forensic applications in South Africa.

Genetic analysis of APOE reveals distinct origins and distribution of ancestry-enrichment haplotypes in the Mexican Biobank

Genetic analysis of APOE reveals distinct origins and distribution of ancestry-enrichment haplotypes in the Mexican Biobank

Environmental DNA Haplotyping Reveals Dispersal Patterns of Invasive Bluegill Sunfish, Lepomis macrochirus, in Japan

ABSTRACTBiological invasions represent a significant threat to global biodiversity. Population genetics plays a crucial role in addressing the invasion history of invasive species, as information on the genetic structure of local populations of invasive species is useful in estimating their source and dispersal. This study aimed to demonstrate the potential of an environmental DNA (eDNA)‐based approach for estimating the dispersal patterns of invasive species, using bluegill sunfish (Lepomis macrochirus), a freshwater fish introduced to Japan in 1960. We developed an eDNA haplotyping assay based on high‐throughput sequencing and validated its ability to reproduce the haplotype distribution of bluegill sunfish in Japan, which had previously been determined through DNA analysis of individual fish. We also detected a negative relationship between the number of detected haplotypes and the geographic distance from Lake Biwa, one of the initial introduction sites, to each study site. This genetic pattern can occur in introduced species as a result of serial founder events during their range expansion. Our results suggested that Lake Biwa is the source of bluegill sunfish distribution in Japan, which is consistent with the invasion records of this species. We demonstrated the potential of the eDNA haplotyping assay for estimating the dispersal patterns of invasive species, which would aid the preparation of countermeasures against emerging biological invasions by simultaneously enabling the early detection and tracking of invasive species.

Amino acid substitution patterns in the <i>E6</i> and <i>E7</i> Proteins of HPV type 16: Phylogeography and Evolution

The E6 and E7 proteins of human papillomavirus (HPV) play a key role in the oncogenesis of papillomavirus infection. Data on the variability of these proteins are limited, and the factors affecting their variability are poorly understood. We analyzed the variability of the currently known sequences of HPV type 16 (HPV16) E6 and E7 proteins, taking into account their geographic origin and year of sample collection, as well as the direction of their evolution in major geographic regions of the world. All sequences belonging to HPV16 genome fragments encoding E6 and E7 oncoproteins were downloaded from the NCBI GenBank database on October 6, 2022. Samples were filtered according to the following parameters: the sequence includes at least one of the two whole open reading frames, the collection date and the country of origin are known. A total of 3,651 full-genome nucleotide sequences encoding the E6 protein and 4,578 full-genome nucleotide sequences encoding the E7 protein were sampled. The nucleotide sequences obtained after sampling and alignment were converted to amino acid sequences and analyzed using MEGA11, R, RStudio, Jmodeltest 2.1.20, BEAST v1.10.4, Fastcov, and Biostrings software. The highest variability in E6 protein structure was recorded at positions 17, 21, 32, 85, and 90, while in E7, positions 28, 29, 51, and 77 were the most variable. The samples were divided geographically into 5 heterogeneous groups: African, European, American, Southwest and South Asia and Southeast Asia. Unique amino acid substitutions (AA-substitutions) in the E6/E7 proteins of HPV16, presumably characteristic of certain ethnic groups, were identified for a number of countries. They are mainly localized in sites of known B- and T-cell epitopes and relatively rarely in structural and functional domains. The revealed differences in AA-substitutions in different ethnic groups and their colocalization with clusters of B- and T-cell epitopes suggest their possible relationship with the geographical distribution of alleles and haplotypes of the major histocompatibility complex (HLA). This may lead to the recognition of a different set of B- and T-cell epitopes of the virus, resulting in regional differences in the direction of epitope drift. Phylogenetic analysis of the nucleotide sequences encoding the E6 protein of HPV16 revealed a common ancestor, confirmed regional clustering of the E6 protein gene sequences by the set of the most common AA-substitutions, and identified cases of reversion of individual AA-substitutions when the virus distribution region changed. For the E7 protein, a similar analysis was not possible due to high sequence homology. Covariance analysis of the pooled sample revealed that there was no relationship between amino acid residues in the E6 protein, in the E7 protein, and between E6 and E7. Data obtained are important for the development of therapeutic vaccines against HPV of high carcinogenic risk.

Carboxyl ester lipase hybrid 1 (CEL-HYB1) haplotypes confer varying risk for chronic pancreatitis

The CEL-HYB1 hybrid allele of the carboxyl ester lipase (CEL) gene and its pseudogene (CELP) has been associated with chronic pancreatitis (CP). Recent work indicated that amino acid positions 488 and 548 in CEL-HYB1 determined pathogenicity. Haplotype Thr488-Ile548 was associated with CP while haplotypes Thr488-Thr548 and Ile488-Thr548 were benign. However, functional analysis revealed that Thr488 is the primary determinant of CEL-HYB1 misfolding and associated endoplasmic reticulum (ER) stress. To address this contradiction, we analyzed a cohort from Hungary and found significantly increased CEL-HYB1 carrier frequency in CP cases (9/319, 2.8%) versus controls (5/618, 0.8%), yielding an odds ratio of 3.6 (95% confidence interval 1.2–10.7, P = 0.024). All CEL-HYB1 positive carriers from Hungary had the Thr488-Thr548 haplotype. We analyzed the haplotype distribution of reported CEL-HYB1 carriers from three European cohorts and found that 14/29 CP cases from Germany and 2/6 CP cases from Poland carried the Thr488-Ile548 haplotype, which was absent in CEL-HYB1 positive controls from Germany (n = 13) and Poland (n = 8). All patients (n = 17) and controls (n = 9) from France carrying CEL-HYB1 contained the Thr488-Thr548 haplotype. Functional studies using transfected cells indicated that both CEL-HYB1 haplotypes induced significant ER stress and the Thr488-Ile548 haplotype had a stronger effect. We conclude that the Thr488-Thr548 haplotype of CEL-HYB1 is widespread in Europe and increases CP risk by almost fourfold. In contrast, the Thr488-Ile548 haplotype is regionally restricted, but confers markedly stronger CP risk.

Genetic diversity and phylogeography of the endemic species Prunus mira in the Qinghai–Tibetan Plateau

Studying the evolutionary history of plants in the Qinghai–Tibetan Plateau region provides a theoretical basis for the conservation and use of plant genetic resources. In this study, we analyzed five chloroplast gene fragments to examine the genetic diversity and phylogeography of Prunus mira in 577 individuals from 32 populations. The results indicated that P. mira populations exhibit high genetic diversity and significant phylogeographic structure (NST > GST). High genetic differentiation (FST = 0.979) and limited gene flow were detected among populations, likely due to geographic isolation. Neutrality tests and mismatch analysis indicated that the P. mira population has not experienced significant expansion during the historical period and remains relatively stable. Additionally, based on haplotype distribution and genetic diversity levels, we propose that P. mira had three refugia during the glacial period. Considering the genetic diversity of P. mira populations, we propose dividing all populations into two conservation units and prioritizing in situ conservation of populations with high genetic diversity within each unit. Furthermore, ex situ conservation of specific populations could prevent the loss of unique genes, such as those in populations with low genetic diversity but distinct haplotypes.

The influence of post-glacial migration and hybridization on the gene pool of marginal Quercus pubescens populations in Central Europe.

In Central Europe, the drought-tolerant downy oak (Quercus pubescens) is at the northern edge of its natural distribution range, often growing in small and spatially isolated populations. Here, we elucidate how the population genetic structure of Central European Q. pubescens was shaped by geographic barriers, genetic drift and introgression with the closely related sessile oak (Q. petraea). 27 Q. pubescens populations from the northern margin of Q. pubescens' natural distribution range were sampled. Based on 16 nuclear microsatellite markers (nSSRs), Bayesian clustering and distance-based analyses were performed to determine the intraspecific genetic structure and to identify genetic barriers. To identify drivers of introgression with Q. petraea, generalised linear models were applied to link levels of introgression with environmental conditions. To track post-glacial migration routes, the spatial distribution of haplotypes based on 8 chloroplast microsatellite markers (cpSSRs) was investigated. Based on nSSRs, the study populations of Q. pubescens were divided into a western and an eastern genetic cluster. Within these clusters, more pronounced genetic substructure was observed in the west, probably due to a rugged topography and limited gene flow. Introgression from Q. petraea was more prevalent at wetter and north-exposed sites and in the west. The identified cpSSR haplotypes followed known migration pathways. Our results suggest two late-glacial refugia in or near the southwestern Alps and the southeastern Alps as potential sources for post-glacial migration. Although some genetic exchange is evident in Northern Italy, south of the Alps, the two clusters remain distinct at a large scale. Landscape features and introgression with Q. petraea shaped the genetic substructure at a smaller scale. Our study provides a comprehensive overview of the genetic structure of Q. pubescens in Central Europe, relevant for conservation.

Regional distribution of polymorphisms associated to the disease-causing gene of spinocerebellar ataxia type 3

IntroductionKnowledge about the distribution and frequency of the respective haplotypes on the wildtype and mutant allele is highly relevant in the context of future gene therapy clinical studies in Spinocerebellar Ataxia Type 3, the most common autosomal dominantly inherited ataxia. Single nucleotide polymorphisms associated to the disease-causing gene, ATXN3, have been determined. We wanted to investigate the frequency and regional distribution of two intragenic single nucleotide polymorphisms (SNPs) in a large European SCA3 cohort and their relation to the clinical phenotype.MethodsThe genotypes of the two polymorphisms at base pair positions 987 and 1118 of the ATXN3 were determined for their co-localization on the normal and expanded allele, respectively, in 286 SCA3 mutation carriers and 117 healthy controls from 11 European sites.ResultsThe distribution of genotypes on the expanded allele differed from those of the wildtype allele of SCA3 mutation carriers and of healthy controls, and was mainly influenced by the regional origin. In our cohort, no particular clinical phenotype was associated with any specific haplotype.ConclusionsOur results confirm distinct allocations of SNPs associated to the expanded ATXN3, and accordingly the consideration of allele-specific therapies.

Haplotypic diversity of <i>Leptidea morsei</i> (Fenton, 1882) (Lepidoptera, Pieridae) on the northwestern periphery of the area

The first data on haplotypic diversity in natural populations of the L. morsei in the north-east of the Russian plain and in the northern regions of the Urals have been obtained. Our interest is caused by the fact that the northwestern border of this species distribution passes here. Six haplotypes were identified, of which five were found only in the studied region. A comparative analysis of haplotypic diversity in different parts of the species range and the geographical distribution of haplotypes allowed us to draw a preliminary conclusion that the population groupings of L. morsei in the north-west of the range have greater genetic similarity with Asian populations than with isolated Central European ones. The settlement of this species to the north of the Russian Plain and the Urals in the post-Glacial epoch obviously took place along the south of the West Siberian Plain through the Southern Trans-Urals.

Multiple ancestral components and complex origins of the Yugur people in Gansu province revealing by 35 Y-STR.

The Yugur people represent one of the ethnic groups residing within the Hexi Corridor, distinguishable by their small population size, linguistic diversity, intricate ancestral components, serving as a quintessential exemplar of the populations inhabiting this corridor. There are still many controversial issues in the academic community regarding the origin, migration, and formation process of the Yugur. In this study, we explored the formation process of the Yugur from the perspective of molecular anthropology, based on the paternal genetic characteristics of the Yugur people. And the study will synthesize multiple disciplines, encompassing ethnology, history and linguistics, in order to offer a thorough analysis. Within this research endeavor, a high-resolution kit comprising 35 Y-STRs was employed to examine 237 male specimens from the Yugur people in Gansu province. Y-SNP haplogroups were deduced through the utilization of Y-STR data. The paternal genetic data from diverse populations documented in published literature were merged to construct a 16 Y-STR dataset, a 25 Y-STR dataset, and a dataset detailing haplogroup frequencies. In this study, we employed haplotype network analysis, principal component analysis, multidimensional scaling analysis, phylogenetic tree construction, and genetic distance calculations to delve into the genetic structure, haplotype distribution, and genetic relationship with neighboring populations of the Yugur people. The findings of this study reveal that the Yugur people are a blend of ancestral lineages from both Eastern and Western Eurasian origins, with approximately 13% of their genetic component traced back to Western Eurasian populations. The Yugur people in Gansu province exhibits a more intimate genetic relationship with the Han, Tibetan, and Mongolian populations inhabiting nearby regions, while showing distinct genetic differences with Turkic-speaking groups like the Uyghur. Based on the merged data, we identified Q1b1a3-L330 and R1a1a-M17 shared with Turkic-speaking people, C2a1a1-F1756, C2a1a3-M504, C2a1a3a-F3796, C2a1a2-M48 and C2b1a1a1a-M407 shared with Mongolic-speaking people, D1a1a-M15 and D1a1b1-P47 shared with Tibetans, and multiple paternal lineages shared with Han people, which are the main paternal lineages of Yugur people, indicating multiple ancestral components and complex origins of Yugur. In this study, we provided a clearer genetic landscape which further supports the formation process and population characteristics of the Yugur people recorded in history, ethnology, and linguistics, and lays the foundation for more detailed studies on population genetics and forensic genetics in the future.

On Non-Random Mating, Adaptive Evolution, and Information Theory.

Population genetics describes evolutionary processes, focusing on the variation within and between species and the forces shaping this diversity. Evolution reflects information accumulated in genomes, enhancing organisms' adaptation to their environment. In this paper, I propose a model that begins with the distribution of mating based on mutual fitness and progresses to viable adult genotype distribution. At each stage, the changes result in different measures of information. The evolutionary dynamics at each stage of the model correspond to certain aspects of interest, such as the type of mating, the distribution of genotypes in regard to mating, and the distribution of genotypes and haplotypes in the next generation. Changes to these distributions are caused by variations in fitness and result in Jeffrey's divergence values other than zero. As an example, a model of hybrid sterility is developed of a biallelic locus, comparing the information indices associated with each stage of the evolutionary process. In conclusion, the informational perspective seems to facilitate the connection between cause and effect and allows the development of statistical tests to perform hypothesis testing against zero-information null models (random mating, no selection, etc.). The informational perspective could contribute to clarify, deepen, and expand the mathematical foundations of evolutionary theory.

Hybridization has localized effect on genetic variation in closely related pine species

BackgroundHybridization is a known phenomenon in nature but its genetic impact on populations of parental species remains less understood. We investigated the evolutionary consequences of the interspecific gene flow in several contact zones of closely related pine species. Using a set of genetic markers from both nuclear and organellar genomes, we analyzed four hybrid zones (384 individuals) and a large panel of reference allopatric populations of parental taxa (2104 individuals from 96 stands).ResultsWe observed reduced genetic diversity in maternally transmitted mitochondrial genomes of pure pine species and hybrids from contact zones compared to reference allopatric populations. The distribution of mtDNA haplotypes followed geographic rather than species boundaries. Additionally, no new haplotypes emerged in the contact zones, instead these zones contained the most common local variants. However, species diverged significantly at nuclear genomes and populations in contact zones exhibited similar or higher genetic diversity compared to the reference stands. There were no signs of admixture in any allopatric population, while clear admixture was evident in the contact zones, indicating that hybridization has a geographically localized effect on the genetic variation of the analyzed pine species.ConclusionsOur results suggest that hybrid zones act as sinks rather than melting pots of genetic diversity. Hybridization influences sympatric populations but is confined to contact zones. The spectrum of parental species ancestry in hybrids reflects the old evolutionary history of the sympatric populations. These findings also imply that introgression may play a crucial role in the adaptation of hybrids to specific environments.

Genetic diversity and molecular evolution of the internal transcribed spacer regions (ITS1–5.8S–ITS2) of Babesia vogeli

Canine babesiosis, a severe haemoparasitic disease caused by Babesia species, has a significant global presence and can be fatal if left untreated. The current study was aimed to perform the population genetic characterization of B. vogeli on the basis of the internal transcribed spacer regions (ITS1–5.8S–ITS2). A maximum likelihood tree constructed with the Hasegawa-Kishino-Yano model grouped all sequences into a single major clade (BvG1), with the exception of a Taiwanese isolate (EF186914), which branched separately. This Taiwanese isolate represented a novel genotype (BvG2) identified in the present study. Nucleotide sequences (n = 62) exhibited 92.5–100 % nucleotide identity among themselves. However, the BvG1 and BvG2 genotypes shared a lower identity of 92.5–93.8 % between them. Notably, the newly generated Indian sequences (n = 21) demonstrated a high degree of homology, with 98.3–100 % identity. Alignment of the nucleotide sequences revealed 58 variations across the dataset. Additionally, 32 sites exhibited variation within the BvG1 genotype, while 56 sites differed between BvG1 and BvG2 genotypes. Within different B. vogeli populations, the nucleotide diversity (π) was low, but the haplotype diversity (Hd) was high. The haplotype diversity of the Indian population, BvG1 genotype, and the combined dataset was ∼0.8 suggesting a high haplotype diversity. The median-joining haplotype network displayed a total of 21 haplotypes, out of which six haplotypes consisted of more than one sequence (2–25 sequences). Haplotype distribution showed significant geographical structuring, with most haplotypes confined to a single country. Only two haplotypes (9.52 %; Hap_1 and Hap_4) were shared between countries, whereas 19 haplotypes (90.48 %) were country-specific. Hap_1, Hap_6, and Hap_4 were the most representative haplotypes, comprising 25, 10, and four sequences, respectively. India exhibited the highest number of haplotypes (h = 13) followed by China (h = 4), the United States of America (h = 3), Taiwan and Tunisia (h = 2), and Thailand (h = 1). Both location-wise and genotype-wise median joining haplotype networks clustered the haplotypes in two groups, representing two distinct genotypes (BvG1 and BvG2). The B. vogeli populations between Thailand and Tunisia exhibited the highest genetic differentiation (FST = 0.80) with a low gene flow (Nm = 0.125) between them. Results of AMOVA revealed a higher genetic variation within populations (69.43 %) as compared to the variation between them (30.57 %). Neutrality indices and the mismatch distributions of the Indian population and the overall dataset of B. vogeli indicated a constant population size to population expansion and population expansion, respectively, with the presence of two distinct genotypes. These data provide information about parasite population genetics and highlight the importance of starting a long-term molecular surveillance program. In conclusion, a high genetic diversity along with the presence of two distinct genotypes of B. vogeli were observed on the basis of internal transcribed spacer regions (ITS1–5.8S–ITS2).

Genomic and metabolomic insights into the selection and differentiation of bioactive compounds in citrus

Bioactive compounds play an increasingly prominent role in breeding functional and nutritive fruit crops such as citrus. However, the genomic and metabolic bases for the selection and differentiation underlying bioactive compound variations in citrus remain poorly understood. In this study, we constructed a species-level variation atlas of genomes and metabolomes using 299 citrus accessions. A total of 19 829 significant SNPs were targeted to 653 annotated metabolites, among which multiple significant signals were identified for secondary metabolites, especially flavonoids. Significant differential accumulation of bioactive compounds in the phenylpropane pathway, mainly flavonoids and coumarins, was unveiled across ancestral citrus species during differentiation, which is likely associated with the divergent haplotype distribution and/or expression profiles of relevant genes, including p-coumaroyl coenzyme A 2′-hydroxylases, flavone synthases, cytochrome P450 enzymes, prenyltransferases, and UDP-glycosyltransferases. Moreover, we systematically evaluated the beneficial bioactivities such as the antioxidant and anticancer capacities of 219 citrus varieties, and identified robust associations between distinct bioactivities and specific metabolites. Collectively, these findings provide citrus breeding options for enrichment of beneficial flavonoids and avoidance of potential risk of coumarins. Our study will accelerate the application of genomic and metabolic engineering strategies in developing modern healthy citrus cultivars.

Exploring Distribution and Evolution of Pi-ta Haplotypes in Rice Landraces across Different Rice Cultivation Regions in Yunnan.

Background: Rice blast, caused by Magnaporthe oryzae, seriously damages the yield and quality of rice worldwide. Pi-ta is a durable resistance gene that combats M. oryzae carrying AVR-Pita1. However, the distribution of the Pi-ta gene in rice germplasms in Yunnan Province has been inadequately studied. Methods: We analyzed the potential molecular evolution pattern of Pi-ta alleles by examining the diversity in the coding sequence (CDS) among rice varieties. Results: The results revealed that 95% of 405 rice landraces collected from different ecological regions in Yunnan Province carry Pi-ta alleles. We identified 17 nucleotide variation sites in the CDS regions of the Pi-ta gene across 385 rice landraces. These variations led to the identification of 28 Pi-ta haplotypes, encoding 12 novel variants. Among these, 5 Pi-ta haplotypes (62 rice landraces) carried R alleles. The evolutionary cluster and network of the Pi-ta haplotypes suggested that the Pi-ta S alleles were the ancestral alleles, which could potentially evolve into R variants through base substitution. Conclusions: This study suggests that Pi-ta alleles are diverse in the rice landraces in Yunnan, and the Pi-ta sites resistant to blast evolved from the susceptible plants of the rice landraces. These results provide the basis for breeding resistant varieties.

South! Phylogeography of the Antarctic fairy shrimp Branchinecta gaini and its closest Patagonian congener Branchinecta granulosa reveals a long-term association of freshwater fauna with the southern continent

Branchinecta gaini Daday, 1910 is the southernmost extant Anostracan species occurring in various localities across Maritime Antarctica. Since this region was almost completely glaciated during the Last Glacial Maximum, the identification of potential glacial refugia and the colonization sequence of freshwater habitats within Maritime Antarctica remains primary biogeographic objective for understanding the evolution of the Antarctic environment. To evaluate the history of B. gaini in Maritime Antarctica, we performed phylogeographic analyses of B. gaini and its closest Patagonian congener Branchinecta granulosa Daday, 1902. We sampled 47 populations from all three Antarctic bioregions where B. gaini occurs – South Orkney Islands, North-west and North-east Antarctic Peninsula. B. granulosa was represented by 8 populations from Patagonia. Molecular analyses of two mitochondrial (16S, COI) and one nuclear (ITS2) marker showed low overall mitochondrial variability and the ambiguous nature of ITS2 variability. The species assessment revealed insufficient genetic differentiation between B. gaini and B. granulosa to consider them two separate species. Therefore, the widely accepted idea that there is a species of Branchinecta endemic to Antarctica and sub-Antarctic islands should be omitted, and B. gaini should be synonymized with B. granulosa. Molecular clock analysis of COI for two substitution rates dated the separation of B. gaini from B. granulosa to the Pleistocene (170 – 502 ka BP and 17 – 50 ka BP, respectively). Therefore, Antarctic populations of B. gaini separated from Patagonian B. granulosa before or during the Last Glacial Maximum, indicating an older association with the southern continent than previously anticipated. The geographic distribution of haplotypes further suggests that B. gaini most likely survived at least the last glacial period in an as-yet unknown refugium in Antarctica.

B-052 Celiac Disease Risk Assessment of HLA-DQ Typing in IgA Deficient Patients

Abstract Background Celiac disease (CeD) is a chronic autoimmune disorder triggered by the ingestion of gluten in persons with the genetic risk factors human leukocyte antigens (HLA)-DQ2 and DQ8. Diagnostic evaluation of patients with suspected CeD often includes serology tests for tissue transglutaminase (tTG) antibodies. While the presence of HLA-DQ2 or DQ8 is required for the initiation and development of CeD, the genetic risk associated with the various alleles is not equivalent. Previous studies in patients with normal total IgA demonstrated the risk gradients of various HLA-DQ2 and DQ8 heterodimers in CeD. However, the impact of both gene variants in IgA deficient patients has not been investigated. In this study, HLA-DQ2 and HLA-DQ8 as risk factors for tTG-IgG positivity in IgA deficient patients were evaluated. Methods Retrospective data was collected from a cohort of individuals (n=3,515) with IgA concentrations below the age-dependent reference interval with suspicion for CeD who were tested for HLA-DQ genotyping and tTG-IgG (reference interval < 6 U/mL) at Mayo Clinic Laboratories. Total IgA was measured using quantitative nephelometry (Siemens BN™ II System); HLA typing was performed using the reverse SSO DNA typing assay (LABType SSO kits). tTG-IgG was determined by enzyme-linked immunosorbent assay (QUANTA Lite R h-tTG, Werfen Diagnostics) on the Dynex Agility System. The prevalence and frequency distribution of HLA-DQ2 and DQ8 haplotypes were determined and the odds ratio (OR) was calculated to evaluate the risk gradient for tTG-IgG positivity based on different HLA-DQ variants. Results Among IgA deficient patients, 58% (n=2,041) expressed HLA-DQ2 or DQ8 haplotypes. Relative to patients without permissive alleles, patients homozygous for HLA-DQ2.5 exhibited a significantly increased risk for tTG-IgG positivity (OR = 10.98, 95% CI: 6.56-18.18, p < 0.001) while those homozygous for HLA-DQ2.2 and DQ8 did not (DQ2.2/DQ2.2_OR = 0.72, 95% CI: 0.04-3.44, p = 0.75; DQ8/DQ8_OR = 0.96, 95% CI: 0.05-4.64, p = 0.97). Patients heterozygous for HLA-DQ2.5 (DQ2.5/x) displayed a lower odds ratio relative to homozygous patients (OR = 3.31, 95% CI: 2.29-4.82, p < 0.001); however, the risk for tTG-IgG positivity increased in the presence of HLA-DQ2.2 (DQ2.5/DQ2.2_OR = 7.59, 95% CI: 4.48-12.65, p < 0.001) or HLA-DQ8 (DQ2.5/DQ8_OR = 6.26, 95% CI: 3.55-10.73, p < 0.001) alleles. Conversely, in the absence of HLA-DQ2.5, HLA-DQ2.2 heterozygotes (DQ2.2/x_OR = 2.80, 95% CI: 1.77-4.39, p < 0.001) and HLA-DQ8 heterozygotes (DQ8/x_OR = 0.99, 95% CI: 0.52-1.77, p = 0.99) displayed lower correlations with tTG-IgG positivity, suggesting a potential risk elevation for tTG-IgG positivity is associated with the combination of DQ2.5 and DQ2.2 or DQ8. Conclusions Our study indicates the risk gradient of HLA-DQ genes in IgA deficient patients. Overall, compared to patients without HLA-DQ2 or DQ8 haplotypes, the homozygous HLA-DQ2.5 genotype had the highest correlation with tTG-IgG positivity, followed by HLA-DQ2.5/DQ2.2 and HLA-DQ2.5/DQ8 heterodimers. The results suggest that HLA-DQ2.2 or HLA-DQ8 alone does not confer risk, but when in the presence of HLA-DQ2.5 these alleles may increase the risk for tTG-IgG positivity. Results from this study shed light on the risk of CeD in patients with IgA deficiency.

HLA Diversity in Transylvanian Ethnic Groups: Consequences for Hematopoietic Cell Transplantation

The HLA profile is essential in cell and tissue transplantation, particularly in patients with autoimmune conditions and infections. Due to the extreme polymorphism in certain HLA loci, it also serves as a key tool for population genetic analysis. This study aimed to identify the allele and haplotype distributions of HLA class I (A, B, and C) and class II (DRB1) genotypes in unrelated hematopoietic stem cell donors. A retrospective analysis was conducted between 2016 and 2020 on 9832 Transylvanian volunteers, divided into Romanian and Hungarian groups based on self-reported ethnicity. Using PCR-SSO for HLA typing, significant differences were found in allele frequencies between ethnic groups. A total of 19 HLA-A, 31 HLA-B, 14 HLA-C, and 13 HLA-DRB1 distinct allele groups were identified between ethnic groups. Notably, B*18, B*51, and C*12 were more frequent in Romanians, while B*44, B*40, and C*07 were more common in Hungarians. Differences in haplotype distributions were also observed, with HLA-A*02~B*18~C*07~DRB1*11 being significantly more frequent in Romanians. Understanding these population-specific HLA profiles can improve donor matching for hematologic diseases, enhancing patient outcomes and access to life-saving hematopoietic stem cell transplantation.