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1.
Am J Bot ; 107(11): 1567-1576, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33150610

RESUMO

PREMISE: Polyploidy may serve to contribute to range size if autopolyploid cytotypes are adapted to differing ecological conditions. This study aims to establish the geographic distribution of cytotypes within the giant goldenrod (Solidago gigantea), and to assess whether cytotypes exhibit differing ecological tolerances and morphology. METHODS: A range-wide set of 629 Solidago gigantea individuals was obtained through field collecting, sampling from herbarium specimens, and incorporating existing chromosome counts. Cytotype of each unknown sample was estimated by observing allele numbers at twelve microsatellite loci, a strategy that was assessed by comparing estimated to known cytotype in 20 chromosome-counted samples. Abiotic ecological differentiation was assessed for two transitions: diploid-tetraploid and tetraploid-hexaploid. Morphological differentiation among cytotypes was assessed. RESULTS: Microsatellite repeat variation accurately estimated cytotype in 85% of samples for which ploidy was known. Applying this approach to samples of unknown ploidy established that the three cytotypes are non-randomly distributed. Although niche modeling and MANOVA approaches identified significant differences in macro-climatic conditions for both cytotype transitions, the tetraploid to hexaploid transition was more substantial. Leaf length and width did not differ among cytotypes. Although leaf vestiture exhibited strong trends, no absolute differences were observed among cytotypes. CONCLUSIONS: With the largest such study to date, we established niche transitions among giant goldenrod cytotypes of differing magnitudes. Collectively, this suggests that whole-genome duplication has contributed to Solidago gigantea's large range.


Assuntos
Solidago , Diploide , Humanos , Ploidias , Poliploidia , Solidago/genética , Tetraploidia
2.
PLoS Biol ; 18(11): e3000930, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33156841

RESUMO

Cues of maternal and paternal origins interact to control seed development, and the underlying molecular mechanisms are still far from clear. Here, we show that TOPOISOMERASE Iα (TOP1α), UP-FRAMESHIFT SUPPRESSOR 1 (UPF1), and TRANSPARENT TESTA GLABRA2 (TTG2) gametophytically, biparentally regulate seed size in Arabidopsis. TOP1α and UPF1 are mainly expressed in antipodal cells, and loss of their function leads to ectopic TTG2 expression in these female gametophytic cells. We further demonstrate that TOP1α and UPF1 directly repress TTG2 expression through affecting its chromatin status and determine its relative expression in antipodal cells versus sperm cells, which controls seed size in a dosage-dependent and parent-of-origin-dependent manner. The molecular interplay among these three genes explains their biparental gametophytic effect during diploidy and interploidy reciprocal crosses. Taken together, our findings reveal a molecular framework of parental interaction for seed size control.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/genética , DNA Topoisomerases Tipo I/genética , RNA Helicases/genética , Fatores de Transcrição/genética , Cruzamentos Genéticos , Diploide , Dosagem de Genes , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Modelos Biológicos , Fenótipo , Plantas Geneticamente Modificadas , Sementes/anatomia & histologia , Sementes/genética , Sementes/crescimento & desenvolvimento , Tetraploidia
3.
Cytogenet Genome Res ; 160(9): 539-553, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33227787

RESUMO

The family Aspredinidae comprises a clade of complex systematic relationships, both from molecular and morphological approaches. In this study, conventional and molecular cytogenetic studies coupled with nucleotide sequencing were performed in 6 Aspredininae species (Amaralia hypsiura, Bunocephalus cf. aloikae, Bunocephalus amaurus, Bunocephalus aff. coracoideus, Bunocephalus verrucosus, and Platystacus cotylephorus) from different locations of the Amazon hydrographic basin. Our results showed highly divergent diploid numbers (2n) among the species, ranging from 49 to 74, including the occurrence of an XX/X0 sex chromosome system. A neighbor-joining phylogram based on the cytochrome c oxidase I (COI) showed that Bunocephalus coracoideus is not a monophyletic clade, but closely related to B. verrucosus. The karyotypic data associated with COI suggest an ancestral karyotype for Aspredinidae with a reduced 2n, composed of bi-armed chromosomes and a trend toward chromosomal fissions resulting in higher diploid number karyotypes, mainly composed of acrocentric chromosomes. Evolutionary relationships were discussed under a phylogenetic context with related species from different Siluriformes families. The karyotype features and chromosomal diversity of Aspredinidae show an amazing differentiation, making this family a remarkable model for investigating the evolutionary dynamics in siluriforms as well as in fish as a whole.


Assuntos
Peixes-Gato/genética , Cromossomos/genética , Animais , Evolução Biológica , Brasil , Peixes-Gato/classificação , Cromossomos/ultraestrutura , Código de Barras de DNA Taxonômico , DNA Ribossômico/genética , Diploide , Evolução Molecular , Feminino , Hibridização in Situ Fluorescente , Cariotipagem , Masculino , Filogenia , RNA Ribossômico 18S/genética , RNA Ribossômico 5S/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Cromossomos Sexuais/genética , Cromossomos Sexuais/ultraestrutura , Especificidade da Espécie
4.
BMC Evol Biol ; 20(1): 148, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-33167862

RESUMO

BACKGROUND: Gene flow and polyploidy have been found to be important in Juniperus evolution. However, little evidence has been published elucidating the association of both phenomena in juniper taxa in the wild. Two main areas were studied in Spain (Eastern Iberian Range and Sierra de Baza) with both diploid and tetraploid taxa present in sympatry. Gene flow and ploidy level were assessed for these taxa and the resulted offspring. RESULTS: Twenty-two allo-triploid hybrids between J. sabina var. sabina and J. thurifera were found in the Eastern Iberian Range population. However, in the Sierra de Baza population no triploids were found. Instead, 18 allo-tetraploid hybrids between two tetraploid taxa: J. sabina var. balkanensis and J. thurifera were discovered. High genetic diversity was exhibited among the tetraploid hybrids at Sierra de Baza, in contrast to the genetically identical triploid hybrids at the Eastern Iberian Range; this suggests meiotic difficulties within the triploid hybrids. In addition, unidirectional gene flow was observed in both studied areas. CONCLUSION: Polyploidy and hybridization can be complementary partners in the evolution of Juniperus taxa in sympatric occurrences. Juniperus was shown to be an ideal coniferous model to study these two phenomena, independently or in concert.


Assuntos
Diploide , Fluxo Gênico , Juniperus , Hibridização Genética , Juniperus/genética , Espanha , Tetraploidia
5.
Nucleic Acids Res ; 48(21): e123, 2020 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-33074315

RESUMO

The recently developed Hi-C technique has been widely applied to map genome-wide chromatin interactions. However, current methods for analyzing diploid Hi-C data cannot fully distinguish between homologous chromosomes. Consequently, the existing diploid Hi-C analyses are based on sparse and inaccurate allele-specific contact matrices, which might lead to incorrect modeling of diploid genome architecture. Here we present ASHIC, a hierarchical Bayesian framework to model allele-specific chromatin organizations in diploid genomes. We developed two models under the Bayesian framework: the Poisson-multinomial (ASHIC-PM) model and the zero-inflated Poisson-multinomial (ASHIC-ZIPM) model. The proposed ASHIC methods impute allele-specific contact maps from diploid Hi-C data and simultaneously infer allelic 3D structures. Through simulation studies, we demonstrated that ASHIC methods outperformed existing approaches, especially under low coverage and low SNP density conditions. Additionally, in the analyses of diploid Hi-C datasets in mouse and human, our ASHIC-ZIPM method produced fine-resolution diploid chromatin maps and 3D structures and provided insights into the allelic chromatin organizations and functions. To summarize, our work provides a statistically rigorous framework for investigating fine-scale allele-specific chromatin conformations. The ASHIC software is publicly available at https://github.com/wmalab/ASHIC.


Assuntos
Montagem e Desmontagem da Cromatina , Cromatina/ultraestrutura , Mapeamento Cromossômico/estatística & dados numéricos , Software , Alelos , Animais , Teorema de Bayes , Cromatina/metabolismo , Mapeamento Cromossômico/métodos , Simulação por Computador , Diploide , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Impressão Genômica , Histonas/genética , Histonas/metabolismo , Humanos , Fator de Crescimento Insulin-Like II/genética , Fator de Crescimento Insulin-Like II/metabolismo , Internet , Camundongos , Polimorfismo de Nucleotídeo Único
6.
Proc Natl Acad Sci U S A ; 117(45): 28191-28200, 2020 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-33106417

RESUMO

Genomic alterations including single-base mutations, deletions and duplications, translocations, mitotic recombination events, and chromosome aneuploidy generate genetic diversity. We examined the rates of all of these genetic changes in a diploid strain of Saccharomyces cerevisiae by whole-genome sequencing of many independent isolates (n = 93) subcloned about 100 times in unstressed growth conditions. The most common alterations were point mutations and small (<100 bp) insertion/deletions (n = 1,337) and mitotic recombination events (n = 1,215). The diploid cells of most eukaryotes are heterozygous for many single-nucleotide polymorphisms (SNPs). During mitotic cell divisions, recombination can produce derivatives of these cells that have become homozygous for the polymorphisms, termed loss-of-heterozygosity (LOH) events. LOH events can change the phenotype of the cells and contribute to tumor formation in humans. We observed two types of LOH events: interstitial events (conversions) resulting in a short LOH tract (usually less than 15 kb) and terminal events (mostly cross-overs) in which the LOH tract extends to the end of the chromosome. These two types of LOH events had different distributions, suggesting that they may have initiated by different mechanisms. Based on our results, we present a method of calculating the probability of an LOH event for individual SNPs located throughout the genome. We also identified several hotspots for chromosomal rearrangements (large deletions and duplications). Our results provide insights into the relative importance of different types of genetic alterations produced during vegetative growth.


Assuntos
Cromossomos Fúngicos/genética , Mutação/genética , Saccharomyces cerevisiae/genética , Mapeamento Cromossômico , Diploide , Conversão Gênica/genética , Rearranjo Gênico/genética , Perda de Heterozigosidade/genética , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Saccharomyces cerevisiae/citologia
8.
PLoS One ; 15(10): e0241206, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33108401

RESUMO

Satellite DNA (satDNA) is one of the major fractions of the eukaryotic nuclear genome. Highly variable satDNA is involved in various genome functions, and a clear link between satellites and phenotypes exists in a wide range of organisms. However, little is known about the origin and temporal dynamics of satDNA. The "library hypothesis" indicates that the rapid evolutionary changes experienced by satDNAs are mostly quantitative. Although this hypothesis has received some confirmation, a number of its aspects are still controversial. A recently developed next-generation sequencing (NGS) method allows the determination of the satDNA landscape and could shed light on unresolved issues. Here, we explore low-coverage NGS data to infer satDNA evolution in the phylogenetic context of the diploid species of the Chenopodium album aggregate. The application of the Illumina read assembly algorithm in combination with Oxford Nanopore sequencing and fluorescent in situ hybridization allowed the estimation of eight satDNA families within the studied group, six of which were newly described. The obtained set of satDNA families of different origins can be divided into several categories, namely group-specific, lineage-specific and species-specific. In the process of evolution, satDNA families can be transmitted vertically and can be eliminated over time. Moreover, transposable element-derived satDNA families may appear repeatedly in the satellitome, creating an illusion of family conservation. Thus, the obtained data refute the "library hypothesis", rather than confirming it, and in our opinion, it is more appropriate to speak about "the library of the mechanisms of origin".


Assuntos
Chenopodium album/genética , DNA de Plantas/análise , DNA Satélite/análise , Diploide , Evolução Molecular , Genoma de Planta , Chenopodium album/crescimento & desenvolvimento , DNA de Plantas/genética , DNA Satélite/genética , Biblioteca Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Especificidade da Espécie
9.
Nat Commun ; 11(1): 5442, 2020 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-33116128

RESUMO

Miscanthus is a perennial wild grass that is of global importance for paper production, roofing, horticultural plantings, and an emerging highly productive temperate biomass crop. We report a chromosome-scale assembly of the paleotetraploid M. sinensis genome, providing a resource for Miscanthus that links its chromosomes to the related diploid Sorghum and complex polyploid sugarcanes. The asymmetric distribution of transposons across the two homoeologous subgenomes proves Miscanthus paleo-allotetraploidy and identifies several balanced reciprocal homoeologous exchanges. Analysis of M. sinensis and M. sacchariflorus populations demonstrates extensive interspecific admixture and hybridization, and documents the origin of the highly productive triploid bioenergy crop M. × giganteus. Transcriptional profiling of leaves, stem, and rhizomes over growing seasons provides insight into rhizome development and nutrient recycling, processes critical for sustainable biomass accumulation in a perennial temperate grass. The Miscanthus genome expands the power of comparative genomics to understand traits of importance to Andropogoneae grasses.


Assuntos
Poaceae/genética , Biomassa , Cromossomos de Plantas/genética , Elementos de DNA Transponíveis , Diploide , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Variação Genética , Genoma de Planta , Genômica , Modelos Genéticos , Filogenia , Poaceae/classificação , Poaceae/crescimento & desenvolvimento , Poliploidia , Saccharum/genética , Estações do Ano , Sorghum/genética
10.
Am J Bot ; 107(10): 1375-1388, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32974906

RESUMO

PREMISE: Whole genome duplication is a major evolutionary event, but its role in ecological divergence remains equivocal. When populations of different ploidy (cytotypes) overlap in space, "contact zones" are formed, allowing the study of evolutionary mechanisms contributing toward ploidy divergence. Multiple contact zones per species' range are often described but rarely leveraged as natural replicates. We explored whether the strength of niche differentiation of diploid and autotetraploid Arabidopsis arenosa varies over distinct contact zones and if the frequency of triploids decreases from seedling to adult stage. METHODS: We characterized ploidy composition and habitat preferences in 264 populations across three contact zones using climatic niche modeling. Ecological differences of cytotypes were also assessed using local vegetation surveys at 110 populations within two contact zones, and at the finer scale within five mixed-ploidy sites. This was complemented by flow cytometry of seedlings. RESULTS: We found no niche differences between diploid and tetraploid populations within contact zones for either climatic or local environmental variables. Comparisons of cytotypes within mixed-ploidy sites found weak niche differences that were inconsistent in direction. Triploid individuals were virtually absent (0.14%) in the field, and they were at a similarly low frequency (0.2%) in ex situ germinated seedlings. CONCLUSIONS: This study demonstrates the strength in investigating different spatial scales across several contact zones when addressing ecological niche differentiation between ploidies. The lack of consistent habitat differentiation of ploidies across the scales and locations supports the recently emerging picture that processes other than ecological differentiation may underlie ploidy coexistence in diploid-autopolyploid systems.


Assuntos
Arabidopsis , Diploide , Arabidopsis/genética , Humanos , Ploidias , Poliploidia , Tetraploidia
11.
Proc Natl Acad Sci U S A ; 117(40): 24947-24956, 2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-32968016

RESUMO

The acquisition of mutations plays critical roles in adaptation, evolution, senescence, and tumorigenesis. Massive genome sequencing has allowed extraction of specific features of many mutational landscapes but it remains difficult to retrospectively determine the mechanistic origin(s), selective forces, and trajectories of transient or persistent mutations and genome rearrangements. Here, we conducted a prospective reciprocal approach to inactivate 13 single or multiple evolutionary conserved genes involved in distinct genome maintenance processes and characterize de novo mutations in 274 diploid Saccharomyces cerevisiae mutation accumulation lines. This approach revealed the diversity, complexity, and ultimate uniqueness of mutational landscapes, differently composed of base substitutions, small insertions/deletions (InDels), structural variants, and/or ploidy variations. Several landscapes parallel the repertoire of mutational signatures in human cancers while others are either novel or composites of subsignatures resulting from distinct DNA damage lesions. Notably, the increase of base substitutions in the homologous recombination-deficient Rad51 mutant, specifically dependent on the Polζ translesion polymerase, yields COSMIC signature 3 observed in BRCA1/BRCA2-mutant breast cancer tumors. Furthermore, "mutome" analyses in highly polymorphic diploids and single-cell bottleneck lineages revealed a diverse spectrum of loss-of-heterozygosity (LOH) signatures characterized by interstitial and terminal chromosomal events resulting from interhomolog mitotic cross-overs. Following the appearance of heterozygous mutations, the strong stimulation of LOHs in the rad27/FEN1 and tsa1/PRDX1 backgrounds leads to fixation of homozygous mutations or their loss along the lineage. Overall, these mutomes and their trajectories provide a mechanistic framework to understand the origin and dynamics of genome variations that accumulate during clonal evolution.


Assuntos
Neoplasias da Mama/genética , Carcinogênese/genética , Mutação/genética , Saccharomyces cerevisiae/genética , Acetiltransferases/genética , Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/patologia , Dano ao DNA/genética , DNA Polimerase Dirigida por DNA , Diploide , Feminino , Endonucleases Flap/genética , Genoma Fúngico/genética , Humanos , Perda de Heterozigosidade/genética , Proteínas de Membrana/genética , Peroxirredoxinas/genética , Rad51 Recombinase/genética , Proteínas de Saccharomyces cerevisiae/genética , Sequenciamento Completo do Genoma
12.
Nat Genet ; 52(10): 1018-1023, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32989320

RESUMO

Potato (Solanum tuberosum L.) is the most important tuber crop worldwide. Efforts are underway to transform the crop from a clonally propagated tetraploid into a seed-propagated, inbred-line-based hybrid, but this process requires a better understanding of potato genome. Here, we report the 1.67-Gb haplotype-resolved assembly of a diploid potato, RH89-039-16, using a combination of multiple sequencing strategies, including circular consensus sequencing. Comparison of the two haplotypes revealed ~2.1% intragenomic diversity, including 22,134 predicted deleterious mutations in 10,642 annotated genes. In 20,583 pairs of allelic genes, 16.6% and 30.8% exhibited differential expression and methylation between alleles, respectively. Deleterious mutations and differentially expressed alleles were dispersed throughout both haplotypes, complicating strategies to eradicate deleterious alleles or stack beneficial alleles via meiotic recombination. This study offers a holistic view of the genome organization of a clonally propagated diploid species and provides insights into technological evolution in resolving complex genomes.


Assuntos
Genoma de Planta/genética , Haplótipos/genética , Anotação de Sequência Molecular , Solanum tuberosum/genética , Alelos , Diploide , Heterozigoto , Tetraploidia
13.
Yi Chuan ; 42(9): 916-925, 2020 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-32952125

RESUMO

Common wheat (T. aestivum L.) is also known as allohexaploid wheat. Its genome is composed of A/B/D sub-genomes from three closely related diploid ancestors. The evolutionary history of common wheat is used as a classic example to illustrate the mechanism of species formation and chromosome number variation in the current genetics class. In recent years, with the rapid development and application of research technologies, there have been many breakthroughs in the study of common wheat, at the cytological, molecular and genomic level. Here, we summarize the latest research achievements on common wheat, and discuss our practice in combining them with the genetics teaching. Our approach is not only a supplement to the current genetics textbooks, but also enables students to realize that genetics is a constantly evolving natural science. We aim to enhance students' interests in learning, as well as their systematic learning abilities on genetics and related scientific research frontiers.


Assuntos
Triticum , Evolução Biológica , Diploide , Genoma de Planta , Poliploidia , Ensino
14.
PLoS One ; 15(9): e0239377, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986735

RESUMO

Double pollen fertility neutral genes, San and Sbn, can control pollen sterility in intersubspecific (indica × japonica) rice hybrids, which has excellent potential to increase rice yield. Previous studies showed that polyploidy could increase the interaction of three pollen sterility loci, i.e. Sa, Sb and Sc, which cause pollen sterility in autotetraploid rice hybrids, and hybrid fertility could be improved by double neutral genes, San and Sbn, in autotetraploid rice hybrids. We compared cytological and transcriptome data between autotetraploid and diploid rice hybrid during meiosis and single microspore stages to understand the molecular mechanism of neutral genes for overcoming pollen sterility in autotetraploid rice hybrids, which harbored double neutral genes. Cytological results revealed that the double neutral genes resulted in higher pollen fertility (76.74%) and lower chromosomal abnormalities in autotetraploid hybrid than in parents during metaphase I, metaphase II, anaphase I and anaphase II. Moreover, autotetraploid rice hybrid displayed stronger heterosis than a diploid hybrid. Compared with diploid rice hybrid, a total of 904 and 68 differently expressed genes (DEGs) were identified explicitly in autotetraploid hybrid at meiosis and single microspore stages, respectively. Of these, 133 and 41 genes were detected in higher-parent dominance and transgressive up-regulation dominance, respectively, which were considered autotetraploid potential heterosis genes, including a meiosis-related gene (Os01g0917500, MSP1) and two meiosis specific-genes (Os07g0624900 and Os04g0208600). Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes pathway (KEGG) analysis revealed that DEGs significantly enriched in amino acid metabolism and photosynthesis metabolism. These results indicated that meiosis-specific and meiosis-related genes, and amino acids and photosynthesis metabolism-related genes contribute to higher yield and pollen fertility in autotetraploid rice hybrid. This study provides a theoretical basis for molecular mechanisms of heterosis in autotetraploid rice harboring double neutral genes for pollen fertility.


Assuntos
Análise Citogenética , Diploide , Perfilação da Expressão Gênica , Genes de Plantas/genética , Oryza/genética , Tetraploidia , Cromossomos de Plantas/genética , Fenótipo , Infertilidade das Plantas/genética , Pólen/genética , Pólen/fisiologia
15.
Nat Commun ; 11(1): 4662, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32938926

RESUMO

Haplotype reconstruction of distant genetic variants remains an unsolved problem due to the short-read length of common sequencing data. Here, we introduce HapTree-X, a probabilistic framework that utilizes latent long-range information to reconstruct unspecified haplotypes in diploid and polyploid organisms. It introduces the observation that differential allele-specific expression can link genetic variants from the same physical chromosome, thus even enabling using reads that cover only individual variants. We demonstrate HapTree-X's feasibility on in-house sequenced Genome in a Bottle RNA-seq and various whole exome, genome, and 10X Genomics datasets. HapTree-X produces more complete phases (up to 25%), even in clinically important genes, and phases more variants than other methods while maintaining similar or higher accuracy and being up to 10×  faster than other tools. The advantage of HapTree-X's ability to use multiple lines of evidence, as well as to phase polyploid genomes in a single integrative framework, substantially grows as the amount of diverse data increases.


Assuntos
Desequilíbrio Alélico , Haplótipos , Análise de Sequência de RNA , Algoritmos , Bases de Dados Genéticas , Diploide , Humanos , Células K562 , Modelos Genéticos , Modelos Estatísticos , Polimorfismo de Nucleotídeo Único , Poliploidia , RNA-Seq , Análise de Sequência de RNA/métodos , Análise de Sequência de RNA/estatística & dados numéricos
16.
Nat Commun ; 11(1): 4794, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32963235

RESUMO

Most human genomes are characterized by aligning individual reads to the reference genome, but accurate long reads and linked reads now enable us to construct accurate, phased de novo assemblies. We focus on a medically important, highly variable, 5 million base-pair (bp) region where diploid assembly is particularly useful - the Major Histocompatibility Complex (MHC). Here, we develop a human genome benchmark derived from a diploid assembly for the openly-consented Genome in a Bottle sample HG002. We assemble a single contig for each haplotype, align them to the reference, call phased small and structural variants, and define a small variant benchmark for the MHC, covering 94% of the MHC and 22368 variants smaller than 50 bp, 49% more variants than a mapping-based benchmark. This benchmark reliably identifies errors in mapping-based callsets, and enables performance assessment in regions with much denser, complex variation than regions covered by previous benchmarks.


Assuntos
Diploide , Complexo Principal de Histocompatibilidade/genética , Benchmarking , Linhagem Celular , Variação Genética , Genoma Humano , Haplótipos , Humanos
17.
BMC Evol Biol ; 20(1): 118, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32928096

RESUMO

BACKGROUND: The Chinese Isoetes L. are distributed in a stairway pattern: diploids in the high altitude and polyploids in the low altitude. The allopolyploid I. sinensis and its diploid parents I. yunguiensis and I. taiwanensis is an ideal system with which to investigate the relationships between polyploid speciation and the ecological niches preferences. RESULTS: There were two major clades in the nuclear phylogenetic tree, all of the populations of polyploid were simultaneously located in both clades. The chloroplast phylogenetic tree included two clades with different populations of the polyploid clustered with the diploids separately: I. yunguiensis with partial populations of the I. sinensis and I. taiwanensis with the rest populations of the I. sinensis. The crow node of the I. sinensis allopolyploid system was 4.43 Ma (95% HPD: 2.77-6.97 Ma). The divergence time between I. sinensis and I. taiwanensis was estimated to 0.65 Ma (95% HPD: 0.26-1.91 Ma). The narrower niche breadth in I.sinensis than those of its diploid progenitors and less niche overlap in the pairwise comparisons between the polyploid and its progenitors. CONCLUSIONS: Our results elucidate that I. yunguinensis and I. taiwanensis contribute to the speciation of I. sinensis, the diploid parents are the female parents of different populations. The change of altitude might have played an important role in allopolyploid speciation and the pattern of distribution of I. sinensis. Additionally, niche novelty of the allopolyploid population of I. sinensis has been detected, in accordance with the hypothesis that niche shift between the polyploids and its diploid progenitors is important for the establishment and persistence of the polyploids.


Assuntos
Adaptação Biológica , Diploide , Especiação Genética , Poliploidia , Traqueófitas/classificação , China , Ecossistema , Filogenia
18.
Proc Biol Sci ; 287(1934): 20200962, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32873209

RESUMO

Although polyploidy is widespread across the plant Tree of Life, its long-term evolutionary significance is still poorly understood. Here, we examine the effects of polyploidy in explaining the large-scale evolutionary patterns within angiosperms by focusing on a single family exhibiting extensive interspecific variation in chromosome numbers. We inferred ploidy from haploid chromosome numbers for 80% of species in the most comprehensive species-level chronogram for the Brassicaceae. After evaluating a total of 94 phylogenetic models of diversification, we found that ploidy influences diversification rates across the Brassicaceae. We also found that despite diversifying at a similar rate to diploids, polyploids have played a significant role in driving present-day differences in species richness among clades. Overall, in addition to highlighting the complexity in the evolutionary consequences of polyploidy, our results suggest that rare successful polyploids persist while significantly contributing to the long-term evolution of clades. Our findings further indicate that polyploidy has played a major role in driving the long-term evolution of the Brassicaceae and highlight the potential of polyploidy in shaping present-day diversity patterns across the plant Tree of Life.


Assuntos
Brassicaceae/genética , Diploide , Poliploidia , Evolução Biológica , Variação Genética , Genoma de Planta , Magnoliopsida , Filogenia , Ploidias
19.
Pan Afr Med J ; 36: 90, 2020.
Artigo em Francês | MEDLINE | ID: mdl-32774649

RESUMO

Partial hydatiform mole (MHP) represents a spectrum of trophoblastic-related disorders occurring during pregnancy. Also known as embryonal mole, it is characterized by a recognizable ovum abnormality with vesicular transformation of villi but with recognizable placental appearance and amniotic cavity containing the fetus. First-trimester spontaneous abortion most commonly suggests the diagnosis. Partial moles rarely persist beyond the first trimester and are then a cause of maternal and fetal complications and diagnostic confusion. MHP of genetic origin is triploid with extra chromosome of paternal origin. The coexistence of normal fetal karyotype and MHP is exceptional. We report a rare case of partial molar pregnancy with liveborn diploid fetus in a 36-year-old woman diagnosed with threat of premature labour associated with placenta previa at 27 weeks of amenorrhea (WA).


Assuntos
Diploide , Doenças Fetais/diagnóstico , Mola Hidatiforme/diagnóstico , Neoplasias Uterinas/diagnóstico , Adulto , Feminino , Humanos , Nascimento Vivo , Trabalho de Parto Prematuro , Placenta Prévia/diagnóstico , Gravidez
20.
Planta ; 252(1): 13, 2020 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-32621079

RESUMO

MAIN CONCLUSION: NtALS1 is specifically expressed in glandular trichomes, and can improve the content of acylsugars in tobacco. ABTRACT: The glandular trichomes of many species in the Solanaceae family play an important role in plant defense. These epidermal outgrowths exhibit specialized secondary metabolism, including the production of structurally diverse acylsugars that function in defense against insects and have substantial developmental potential for commercial uses. However, our current understanding of genes involved in acyl chain biosynthesis of acylsugars remains poor in tobacco. In this study, we identified three acetolactate synthase (ALS) genes in tobacco through homology-based gene prediction using Arabidopsis ALS. Quantitative real-time PCR (qRT-PCR) and tissue distribution analyses suggested that NtALS1 was highly expressed in the tips of glandular trichomes. Subcellular localization analysis showed that the NtALS1 localized to the chloroplast. Moreover, in the wild-type K326 variety background, we generated two ntals1 loss-of-function mutants using the CRISPR-Cas9 system. Acylsugars contents in the two ntals1 mutants were significantly lower than those in the wild type. Through phylogenetic tree analysis, we also identified NtALS1 orthologs that may be involved in acylsugar biosynthesis in other Solanaceae species. Taken together, these findings indicate a functional role for NtALS1 in acylsugar biosynthesis in tobacco.


Assuntos
Acetolactato Sintase/genética , Açúcares/metabolismo , Tabaco/metabolismo , Tricomas/enzimologia , Acetolactato Sintase/metabolismo , Proteínas de Arabidopsis/genética , Sistemas CRISPR-Cas , Cloroplastos/enzimologia , Diploide , Regulação da Expressão Gênica de Plantas , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Tabaco/genética , Tricomas/genética
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