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Repeated evolution on oceanic islands: comparative genomics reveals species-specific processes in birds.

Understanding the interplay between genetic drift, natural selection, gene flow, and demographic history in driving phenotypic and genomic differentiation of insular populations can help us gain insight into the speciation process. Comparing patterns across different insular taxa subjected to similar selective pressures upon colonizing oceanic islands provides the opportunity to study repeated evolution and identify shared patterns in their genomic landscapes of differentiation. We selected four species of passerine birds (Common Chaffinch Fringilla coelebs/canariensis, Red-billed Chough Pyrrhocorax pyrrhocorax, House Finch  Haemorhous mexicanus and Dark-eyed/island Junco Junco hyemalis/insularis) that have both mainland and insular populations. Changes in body size between island and mainland populations were consistent with the island rule. For each species, we sequenced whole genomes from mainland and insular individuals to infer their demographic history, characterize their genomic differentiation, and identify the factors shaping them. We estimated the relative (Fst) and absolute (dxy) differentiation, nucleotide diversity (π), Tajima's D, gene density and recombination rate. We also searched for selective sweeps and chromosomal inversions along the genome. All species shared a marked reduction in effective population size (Ne) upon island colonization. We found diverse patterns of differentiated genomic regions relative to the genome average in all four species, suggesting the role of selection in island-mainland differentiation, yet the lack of congruence in the location of these regions indicates that each species evolved differently in insular environments. Our results suggest that the genomic mechanisms involved in the divergence upon island colonization-such as chromosomal inversions, and historical factors like recurrent selection-differ in each species, despite the highly conserved structure of avian genomes and the similar selective factors involved. These differences are likely influenced by factors such as genetic drift, the polygenic nature of fitness traits and the action of case-specific selective pressures.

Animals

Distinct types of selection and genetic architecture shape molecular variation during the domestication of vegetable crops.

Humans select vegetable crops with desirable traits via a complex evolutionary process called domestication, generating a variety of cultivars worldwide. With advances in sequencing technologies, genomic scans for "signatures of selection" are widely used to identify target loci of selection. In the early phases of domestication, humans tended to favor similar sets of phenotypes in diverse crops, resulting in "domestication syndrome" and parallel evolution in multiple species. Subsequently, adaptation to distinct environments or different consumer preferences has diversified crop cultivars. Here, we review molecular and population genetic studies on genes affecting trait evolution during this complex process. We emphasize that, depending on interactions among different types of selection (directional selection within or divergent selection between groups), the genetic architecture of the target trait (Mendelian or polygenic), and the origin of the causal variant (new mutation or standing variation), the resulting molecular patterns of variation can be highly diverse. Situations in which the typical hard selective sweep model could be applied may be limited. Therefore, it is crucial to obtain a thorough understanding of the target species' historical, environmental, and ecological contexts.

Domestication

Adaptation to climate across the Arabidopsis thaliana genome.

Understanding the genetic bases and modes of adaptation to current climatic conditions is essential to accurately predict responses to future environmental change. We conducted a genome-wide scan to identify climate-adaptive genetic loci and pathways in the plant Arabidopsis thaliana. Amino acid-changing variants were significantly enriched among the loci strongly correlated with climate, suggesting that our scan effectively detects adaptive alleles. Moreover, from our results, we successfully predicted relative fitness among a set of geographically diverse A. thaliana accessions when grown together in a common environment. Our results provide a set of candidates for dissecting the molecular bases of climate adaptations, as well as insights about the prevalence of selective sweeps, which has implications for predicting the rate of adaptation.

Acclimatization

A wild soybean MADS-box gene GsAGL62 improves seed weight by enhancing cytokinin signaling and cell proliferation.

Soybean seed weight is a key yield determinant, but the transcriptional mechanisms connecting hormone signaling to seed growth are poorly understood. Here, we identify GsAGL62, a wild soybean MADS-box transcription factor located within a previously mapped hundred-seed weight (HSW) locus and a domestication-associated selective sweep. Functional analyses show that overexpression of GsAGL62 in cultivated soybean significantly increases HSW, whereas ethyl methanesulfonate (EMS)-induced gmagl62 mutants reduce it. Integrated transcriptomic and metabolomic analyses reveal that GsAGL62 enhances cytokinin accumulation and signaling cytokinin-associated responses, accompanied by increased expression of genes involved in cell proliferation. Mechanistically, GsAGL62 directly binds to the promoter of the conserved growth inhibitor GmATPK2 and represses its transcription. Consistently, independent EMS-induced gmatpk2 mutants exhibit increased seed weight, supporting GmATPK2 as a downstream negative regulator of seed growth. Population genetic analyses further reveal strong differentiation of GsAGL62 promoter haplotypes during soybean domestication and improvement. These haplotypes show differential promoter activities and are associated with distinct agronomic performance, suggesting that cis-regulatory variation at GsAGL62 contributes to its selection during soybean improvement. Collectively, our findings establish a regulatory module linking GsAGL62 to cytokinin-associated responses, cell proliferation, and seed growth, and highlight GsAGL62 as a potential target for soybean yield improvement.

Cell proliferation

Genomic insights into the population history of fat-tailed sheep and identification of two mutations that contribute to fat tail adipogenesis.

INTRODUCTION: Since their domestication, domestic sheep (Ovis aries) have been culturally and economically significant farming animals worldwide. Fat-tailed sheep serve as a unique genetic resource for understanding adipogenesis and adaptive evolution in livestock. OBJECTIVES: Several genomic analyses have been conducted on various sheep breeds to elucidate the genome and regulation mechanism of the fat tail trait, prior genomic studies have failed to reconcile conflicting evidence about the genetic basis of tail morphology, particularly regarding the roles of PDGFD and BMP2. METHODS: Here, we conducted whole-genome resequencing of 283 sheep, encompassing 66 domestic breeds and 5 wild ovine species, to investigate the domestication history and selection signatures of fat-tailed sheep. Additionally, we performed transcriptome sequencing on adipose tissue to identify differentially expressed genes and cellular assays to validate these results. RESULTS: Demographic analysis revealed that domestic sheep descended from Asiatic mouflon and fat-tailed sheep began to diverge from thin-tailed sheep approximately 4.4-7.5 thousand years ago in East Asia. Chinese indigenous sheep were classified into Mongolian, Kazakh, Tibetan, and Yunnan populations. The Yunnan population may have experienced more recent genetic introgression from wild species, rather than an independent domestication event. Moreover, many potential regions associated with the fat-tailed phenotype (DDI1, PDGFD, and BMP2) were identified by selective sweep and genome-wide association analyses. Additionally, a fine-scale analysis of fat-tailed and thin-tailed sheep revealed two novel mutations: a G/A missense variant of PDGFD (Chr15: 3900312) and a C/T missense variant of BMP2 (Chr13: 48462350), both of which were significantly associated with tail adiposity. Functional validation demonstrated that mutant A-PDGFD significantly activated PFGFD expression and reduced fat deposition compared to wildtype. The C-BMP2 mutant activated BMP2 expression and promoted preadipocyte fat deposition. CONCLUSION: Our study provides the first evidence that these genes jointly regulate fat tail development through complementary mechanisms: PDGFD promotes adipose expansion, whereas BMP2 modulates energy partitioning. These findings offer new insights into the evolutionary history of fat-tailed sheep and identify potential targets for precision breeding in small ruminants.

Animals

Genomic separation of Salish Sea and Pacific outer coast populations of the keystone sea star Pisaster ochraceus.

Environmental boundaries shape genetic diversity through the interacting effects of geographic distance, local adaptation, and constraints on gene flow. The ochre sea star (Pisaster ochraceus), an intertidal keystone predator, has long been considered to have limited spatial genetic structure along the North American Pacific coast, likely due to its extended larval dispersal period and high potential for gene flow. Here, we characterize spatial genomic variation in Pisaster ochraceus using whole-genome sequencing data from individuals spanning nearly 3000 kilometers of coastline from Alaska to southern California. Analyses of putatively neutral SNPs demonstrate considerable mixing across the latitudinal range, but also reveal substantial structure between outer Pacific coast populations and those within the semi-enclosed Salish Sea, suggesting restricted gene flow and demographic divergence between these regions. Genomic divergence is further supported by evidence of selection, with outlier loci highlighting extended regions of low diversity in the Salish Sea, consistent with recent selective sweeps and potential local adaptation to distinct estuarine conditions. These findings support the role of oceanographic barriers and environmental heterogeneity in shaping population structure in Pisaster ochraceus, challenging earlier expectations of range-wide homogeneity and providing insight into the persistence of this keystone marine species in a rapidly changing world.

Pisaster

The ecology, evolution, and physiology of Cardinium: a widespread heritable endosymbiont of invertebrates.

Candidatus Cardinium hertigii (Cardinium) are maternally transmitted obligate intracellular bacteria found in a wide range of invertebrate hosts, including arthropods and nematodes. Infection with Cardinium has substantial consequences for host biology, with many strains manipulating host reproduction to favor symbiont transmission by (i) feminizing male hosts, (ii) altering host sex allocation, (iii) inducing parthenogenesis, or (iv) causing cytoplasmic incompatibility. Other Cardinium strains can confer benefits to their host or alter host behavior. Cardinium-modified host phenotypes can result in selective sweeps of cytological elements through host populations and potentially reinforce host speciation. Cardinium has potential for applications in controlling arthropod pest species and arthropod-vectored disease transmission, although much remains to be explored regarding Cardinium physiology and host interactions. In this review, we provide an overview of Cardinium evolution and host distribution. We describe the various host phenotypes associated with Cardinium and how biological and environmental factors influence these symbioses. We also provide an overview of Cardinium metabolism, physiology, and potential mechanisms for interactions with hosts based on recent studies using genomics and transcriptomics. Finally, we discuss new methodologies and directions for Cardinium research, including improving our understanding of Cardinium physiology, response to environmental stress, and potential for controlling arthropod pest populations.

Symbiosis

Natural variation in GmSOP5 regulates seed oil and protein content during soybean domestication.

Seed oil content, protein content, and yield are agronomically important, correlated traits that determine the economic value of soybean (Glycine max). However, improving seed quality and yield simultaneously is challenging because gains in one breeding target often compromise the other, and the genetic basis of this trade-off is poorly understood. Here, we performed a genome-wide association study of 429 diverse soybean accessions and identified Seed Oil and Protein 5 (SOP5), which encodes a kinesin protein, as a key locus associated with seed oil and protein content. Knockout and overexpression experiments demonstrated that GmSOP5 positively affects seed oil content and 100-seed weight and negatively influences seed protein content. GmSOP5 is located in a selective sweep region, and the domestication-related GmSOP5H1 allele is nearly fixed in cultivated soybean, contributing to increased seed size, weight, and oil content and reduced protein content. Field trials demonstrated that neither loss-of-function GmSOP5-edited mutants, which have increased seed protein content, nor GmSOP5-overexpression lines, which have increased seed oil content, differed significantly in yield from wild-type plants, because changes in plant architecture were offset by changes in seed weight. Our results shed light on soybean domestication and suggest how pleiotropy can be harnessed in breeding to enhance seed quality without compromising yield.

GWAS

Population genomics of Plasmodium malariae from 4 African countries.

BACKGROUNDMalaria caused by Plasmodium malariae is geographically widespread and sometimes associated with prolonged infection, yet little is known about its genomic epidemiology.METHODSWe performed hybrid capture and whole-genome sequencing of 77 isolates collected from Cameroon (n = 7), the Democratic Republic of the Congo (n = 16), Nigeria (n = 4), and Tanzania (n = 50) between 2015 and 2021, analyzing parasite genetic population structure and demography.RESULTSThere is no evidence of geographic population structure. Nucleotide diversity was significantly lower than in colocalized P. falciparum isolates, while linkage disequilibrium was significantly higher. Genome-wide selection scans identified no erythrocyte invasion ligands or antimalarial resistance orthologs as top hits; however, targeted analyses of these loci revealed evidence of selective sweeps around 4 erythrocyte invasion ligands and 6 antimalarial resistance orthologs. Demographic inference modeling suggests that African P. malariae is recovering from a bottleneck.CONCLUSIONP. malariae is genomically atypical among human Plasmodium spp. and lacks strong population structure in Africa. The low diversity has potential impacts on understanding persistent versus new infection through genomic epidemiology.FUNDINGBill & Melinda Gates Foundation (grant 002202), USAID/PMI through Jhpiego and CDC, NIH (T32AI007151, T32AI070114, R01AI107949, R01AI129812, R21 AI148579, R01AI137395, R21AI152260, R01AI132547, and K24AI134990), and the DELTAS Africa initiative (DELGEME grant 107740/Z/15/Z).

Plasmodium malariae

3D chromatin remodeling during domestication defines novel targets for crop improvement.

Three-dimensional (3D) genome folding shapes gene regulation, yet the genetic underpinnings linking 3D genome evolution to phenotypic innovation during domestication remain elusive. Using population-scale Hi-C profiling of 34 semi-wild and 267 cultivated allotetraploid cottons, we generated a pan-3D genome atlas capturing extensive diversity in topologically associating domains (TADs) and chromatin loops. Chromatin interactome-wide association studies identified 105 TAD reconfigurations and 58 loop rewirings that were established as the 3D chromatin basis of fiber quality, boosting heritability estimates for fiber strength by 16% and fiber length by 20%. We reveal that domestication selection within sequence-defined sweeps fixed 57% of 3D conformation signatures, thereby decoupling sequence-level from chromatin-level selection and shifting the subgenome expression balance of 39 homoeologs in cultivated cotton. Sequence-based modeling and mutational analyses identified the C2H2 zinc-finger protein YY1 as a conserved mediator of 3D genome organization. This study provides a resource for redefining precision-breeding paradigms by harnessing cryptic 3D chromatin targets.

3D genome

LCORL and STC2 Variants Increase Body Size and Growth Rate in Cattle and Other Animals.

Natural variants can significantly improve growth traits in livestock and serve as safe targets for gene editing, thus being applied in animal molecular design breeding. However, such safe and large-effect mutations are severely lacking. Using ancestral recombination graphs, we investigated recent selection signatures in beef cattle breeds, pinpointing sweep-driving variants in the LCORL and STC2 loci with notable effects on body size and growth rate. The ACT-to-A frameshift mutation in LCORL occurs mainly in central-European cattle, and stimulates growth. Remarkably, convergent truncating mutations were also found in commercial breeds of sheep, goats, pigs, horses, dogs, rabbits, and chickens. In the STC2 gene, we identified a missense mutation (A60P) located within the conserved region across vertebrates. We validated the two natural mutations in gene-edited mouse models, where both variants in homozygous carriers significantly increase the average weight by 11%. Our findings provide insights into a seemingly recurring gene target of body size enhancing truncating mutations across domesticated species, and offer valuable targets for gene editing-based breeding in animals.

Animals

The Jumonji C domain-containing proteins GmJMJ19 and GmJMJ20 link florigen signaling with epigenetic regulation of photoperiodic flowering and post-flowering plant height in soybean.

Soybean (Glycine max) is a photoperiod-sensitive legume whose latitudinal adaptation depends on the precise control of flowering time and plant height. Histone demethylases of the JmjC domain-containing (JMJ) protein family have been implicated in these processes across plant species, but their specific roles in soybean remain largely unexplored. Here, we identify soybean GmJMJ19 and GmJMJ20, two closely related JMJD5/KDM8 orthologs, as master epigenetic regulators that coordinately control both photoperiodic flowering and post-flowering plant height. Both genes exhibit intrinsic, rhythmic expression peaking at ZT12, and their encoded proteins physically interact with the florigen proteins FT2a and FT5a. Loss-of-function mutants display delayed flowering under long days (LDs) and increased plant height under both LDs and short days (SDs), whereas overexpression phenocopies the mutant flowering phenotype, indicating revealing a critical dosage requirement for proper function. Mechanistically, GmJMJ19 and GmJMJ20 are recruited by the FT/FD transcriptional complex to directly activate AP1a and AP1c expression through chromatin modulation. Population genomic analyses reveal distinct selection signatures: GmJMJ19 underwent sustained directional selection during cultivation, whereas GmJMJ20 experienced an early domestication sweep with limited subsequent change. Haplotype analysis identifies coordinated latitudinal clines, with the JMJ19H1/JMJ20H1 combination predominating at high latitudes to promote early flowering and limit height, while JMJ19H2/JMJ20H2 and wild JMJ19H3/JMJ20H3 alleles prevail at low latitudes, conferring later flowering and increased height. Collectively, our findings establish GmJMJ19 and GmJMJ20 as central chromatin regulators linking florigen signaling to downstream target expression and provide valuable allelic resources for breeding regionally adapted soybean varieties across a wide range of latitudinal environments.

Histone modulation

Efficient Detection and Characterization of Targets of Natural Selection Using Transfer Learning.

Natural selection leaves detectable patterns of altered spatial diversity within genomes, and identifying affected regions is crucial for understanding species evolution. Recently, machine learning approaches applied to raw population genomic data have been developed to uncover these adaptive signatures. Convolutional neural networks (CNNs) are particularly effective for this task, as they handle large data arrays while maintaining element correlations. However, shallow CNNs may miss complex patterns due to their limited capacity, while deep CNNs can capture these patterns but require extensive data and computational power. Transfer learning addresses these challenges by utilizing a deep CNN pretrained on a large dataset as a feature extraction tool for downstream classification and evolutionary parameter prediction. This approach reduces extensive training data generation requirements and computational needs while maintaining high performance. In this study, we developed TrIdent, a tool that uses transfer learning to enhance detection of adaptive genomic regions from image representations of multilocus variation. We evaluated TrIdent across various genetic, demographic, and adaptive settings, in addition to unphased data and other confounding factors. TrIdent demonstrated improved detection of adaptive regions compared to recent methods using similar data representations. We further explored model interpretability through class activation maps and adapted TrIdent to infer selection parameters for identified adaptive candidates. Using whole-genome haplotype data from European and African populations, TrIdent effectively recapitulated known sweep candidates and identified novel cancer, and other disease-associated genes as potential sweeps.

Selection, Genetic

Efficient detection and characterization of targets of natural selection using transfer learning.

Natural selection leaves detectable patterns of altered spatial diversity within genomes, and identifying affected regions is crucial for understanding species evolution. Recently, machine learning approaches applied to raw population genomic data have been developed to uncover these adaptive signatures. Convolutional neural networks (CNNs) are particularly effective for this task, as they handle large data arrays while maintaining element correlations. However, shallow CNNs may miss complex patterns due to their limited capacity, while deep CNNs can capture these patterns but require extensive data and computational power. Transfer learning addresses these challenges by utilizing a deep CNN pre-trained on a large dataset as a feature extraction tool for downstream classification and evolutionary parameter prediction. This approach reduces extensive training data generation requirements and computational needs while maintaining high performance. In this study, we developed TrIdent, a tool that uses transfer learning to enhance detection of adaptive genomic regions from image representations of multilocus variation. We evaluated TrIdent across various genetic, demographic, and adaptive settings, in addition to unphased data and other confounding factors. TrIdent demonstrated improved detection of adaptive regions compared to recent methods using similar data representations. We further explored model interpretability through class activation maps and adapted TrIdent to infer selection parameters for identified adaptive candidates. Using whole-genome haplotype data from European and African populations, TrIdent effectively recapitulated known sweep candidates and identified novel cancer, and other disease-associated genes as potential sweeps.

Journal Article

Host feeding patterns of Connecticut mosquitoes (Diptera: Culicidae).

Blood-engorged Coquillettidia perturbans, Psorophora ferox, Culex, Culiseta, and Aedes mosquitoes were collected principally by sweep net from salt marsh and woodland habitats in Connecticut. Of the 570 mosquitoes tested, precipitin tests identified the origins of 517 blood meals and revealed distinct host feeding patterns. Aedes mosquitoes fed chiefly on mammals; A. abserratus, A. cantator, and A. vexans showed selectivity for cattle and (or) horses. A. cantator also obtained blood from avian hosts and, in some instances, showed mixed passerine-mammal blood meals. These findings increase the vector potential of this salt marsh mosquito for eastern equine encephalomyelitis virus. Feedings on deer by A. abserratus suggest potential involvement of this mosquito in the transmission of certain subtypes of California encephalitis. Culex-pipiens, C. restuans, Culiseta melanura, and Cs. morsitans dyari acquired blood almost exclusively from passeriform birds.

Aedes

[The objective frequency decrement test (OFDT): a new objective EEG-test for determination of the difference limen for frequencies (author's transl)].

Subjective methods measuring the difference limen for frequencies (DLF) take a lot of time and are not reliable. You can find this fact not only while testing normal subjects, but also while testing patients with hearing loss combined with tinnitus. Therefore this new objective DLF-test has been developed. Apart from the testing function for clinical purpose, the different results of other studies can also be controlled. After 1080 msec a pure tone is changed to a lower frequency for a period of 670 msec. Immediately after the tone is finished a picture is presented. As a control pure tones of unvarying pitch are offered. This stimulus sequence is repeated for several times. The expectancies to the change of pitch and to the picture produce a negative slow potential shift (Walter's CNV) in the EEG. The perception of frequency change yields to a late evoked potential and to a DC-shift; as a result of the optimum conditions of the expectancy-situation and the appropriate recording-technique only 5-10 sweeps must be summed up to obtain a potential, sometimes it even can be seen in the "raw-EEG". The test makes a differentiation between a just believed and a real perception possible. A sample of subjects with normal hearing and a subgroup (musicians) were selected for the standardization. Because of objectivity, reliability and economy the test can be used for clinical application.

Electroencephalography

Electron spin resonance in zero magnetic field of the reaction center triplet of photosynthetic bacteria.

The decay rates kx, ky, kz of the individual spin levels of the light-induced triplet state have been accurately measured by the zero-field resonance technique under conditions of very low light intensity and a microwave sweep rate of 2.5 MHz/microseconds, which is in excess of that commonly used in optical detection magnetic resonance experiments. The rates ku found correspond well with those previously determined under somewhat different conditions (Hoff, A.J. (1976) Biochim. Biophys. Acta 440, 765--771) and with those inferred from the decay at 4.2 degrees K of the triplet-triplet absorption after picosecond excitation (Parson, W.W. and Monger, T.G. (1977) Brookhaven Symp. Biology 28, 195--212). Thus there seems no reason to doubt that PR corresponds to the triplet state detected by ESR. In a recent publication Clarke and Connors (Clarke, R.H. and Conners, R.E. (1976) Chem. Phys. Lett. 42, 69--72) published values of the rates ku which differ substantially from ours and which lead to a mean lifetime in excess of that of PR. We show that erroneous rates are obtained when the microwave sweep rate is not made fast relative to the decay of the individual spin levels. Zero-field splitting parameters for a member of photosynthetic bacteria have been measured with an accuracy of better than 0.4% for D and 1% for E. The enhanced precision as compared to conventional ESR allows one to discriminate between species of one family. Deuteration reduces the ku values by a factor of about 2, with little spin selectivity. This effect is much larger than previously observed for chlorophyll a. The present results explain the decrease in fluorescence intensity observed on microwave saturation in zero-field optical detection magnetic resonance experiments, and they also show that the simple exciton model is inadequate to derive the geometry of the reaction center dimer from the observed zerofield splitting and decay rates.

Electron Spin Resonance Spectroscopy

Efficacy...what's that??

We need to develop techniques for measuring the usefulness of medical services. If resources are limited, and we cannot do all the diagnostic tests we would like to do, we must be able to select those that are most useful. To do this we need to known how to weigh benefits against risks and how to measure the worth of a given outcome. This article discusses efficacy, in diagnosis, management, and outcome. Diagnostic efficacy of a test is measured by its ability to change the probability of disease (pre- versus post-test likelihood). Management efficacy is a measure of how the test changes patient management. Outcome efficacy, which may take years to evaluate, is the ultimate yardstick of usefulness. Even though there are many problems in estimating the likelihood of a disease (subjectivity, varying terminology, etc.), physicians can make reasonably close estimates, as shown by the American College of Radiology's Efficacy Study, which analyzed the diagnostic process in 9000 cases. Efficacy studies may be a mixed blessing, however, as they may result in overly strict criteria and sweeping economic changes. They may be ignored because of the difficulty in following the "perfect" protocol for a given clinical situation, and it remains to be shown that they themselves are efficacious. Nevertheless, we are finally coming to grips with the question of how useful our tests are in patient management.

Cost-Benefit Analysis