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1.
Gene ; 862: 147259, 2023 Apr 30.
Article in English | MEDLINE | ID: mdl-36758844

ABSTRACT

Trehalose is a primary sugar and its distribution across the insect body, regulated by trehalose transporters (TRETs), is essential for sugar metabolism and energy homeostasis. The large diversity of Tret-like sugar transporters (ST), belonging to SLC2A transporter family, in polyphagous insects probably contributes to their extremely adaptive nature. We aim to study spatio-temporal expression dynamics and functional relevance of ST transcript variants in the lepidopteran model organism, Helicoverpa armigera. Identification of 69 putative Tret-like HaST transcript variants from databases and their digital gene expression analysis indicated tissue and development-specific expression patterns. Phylogenetic and sequence similarity network analysis of HaSTs signify evolutionary divergence, while motif and structure analysis depicted conserved signatures. In vitro gene expression validation for selected genes depicts that HaST09 and 69 are fat body and haemolymph-specific. While, HaST06, 30, 36 and 57 are developmental stage or sex-specific. HaST69 has high expression in the haemolymph of fifth instar larvae. In the presence of trehalose metabolism inhibitors and abiotic stress, HaSTs expression show dysregulation, indicating their possible association with trehalose metabolism and stress recovery. In vivo gene silencing of HaST69 resulted in reduced trehalose accumulation in the insect body, suggesting its plausible role in sugar metabolism. The overall understanding of HaST diversity and expression dynamics highlights their putative roles in sugar transport during adaptation and stress recovery of insects.


Subject(s)
Moths , Trehalose , Animals , Male , Female , Trehalose/metabolism , Phylogeny , Moths/genetics , Larva/genetics , Insecta/genetics , Membrane Transport Proteins/genetics
2.
Hemodial Int ; 26(2): 147-159, 2022 04.
Article in English | MEDLINE | ID: mdl-34989465

ABSTRACT

INTRODUCTION: Acute kidney injury (AKI) is a clinical condition characterized by an abrupt increase in serum creatinine levels due to functional changes in the kidneys from a newfound insult or injury. For supportive treatment, continuous renal replacement therapy (CRRT) is one of the most widely used modalities due to its precise control of fluid balance over extended periods of time. However, its complications include circuit clotting, the most frequent cause for CRRT interruption. Vascular access and circuit management were found to be major determinants of performance efficiency. Anticoagulation required to prevent clotting has the downside of increasing the risk of bleeding, especially in the setting of overdosage. Hence, a delicate balance needs to be maintained consistently. METHODS: This study explores the adequacy of non-anticoagulation measures in the prevention of circuit clotting. A comprehensive literature search was conducted using PubMed/Medline and Embase databases to include all relevant studies. FINDINGS: The most-effective CRRT catheter would be made of nonthrombogenic material, noncuffed and nontunneled with separate lumens for arterial and venous blood. Further, studies show that blood flow during the process is optimized at 200 ml/min, which can be lowered in the pediatric population due to more narrow catheters. Platelet count and hematocrit need to be closely monitored as levels above 450,000 × 106 /L and 0.40, respectively, increase risk of clotting. Predilution is a non-anticoagulation technique to reduce the risk of clotting by returning replacement solution to the blood before it reaches the filter. Also, biocompatible membranes such as polyacrylonitrile or polysulfone activate the coagulation cascade significantly less than the conventional cellulose-based membranes, thereby reducing clotting chances. DISCUSSIONS: With the advent of such techniques and maneuvers, anticoagulation can be efficiently maintained in patients undergoing CRRT without increasing the risk of bleeding.


Subject(s)
Acute Kidney Injury , Continuous Renal Replacement Therapy , Acute Kidney Injury/etiology , Acute Kidney Injury/therapy , Anticoagulants/pharmacology , Blood Coagulation , Child , Heparin/therapeutic use , Humans , Renal Dialysis/methods , Renal Replacement Therapy/methods
3.
Cells ; 10(12)2021 12 18.
Article in English | MEDLINE | ID: mdl-34944087

ABSTRACT

Atypical hemolytic uremic syndrome (aHUS) is a rare disorder characterized by dysregulation of the alternate pathway. The diagnosis of aHUS is one of exclusion, which complicates its early detection and corresponding intervention to mitigate its high rate of mortality and associated morbidity. Heterozygous mutations in complement regulatory proteins linked to aHUS are not always phenotypically active, and may require a particular trigger for the disease to manifest. This list of triggers continues to expand as more data is aggregated, particularly centered around COVID-19 and pediatric vaccinations. Novel genetic mutations continue to be identified though advancements in technology as well as greater access to cohorts of interest, as in diacylglycerol kinase epsilon (DGKE). DGKE mutations associated with aHUS are the first non-complement regulatory proteins associated with the disease, drastically changing the established framework. Additional markers that are less understood, but continue to be acknowledged, include the unique autoantibodies to complement factor H and complement factor I which are pathogenic drivers in aHUS. Interventional therapeutics have undergone the most advancements, as pharmacokinetic and pharmacodynamic properties are modified as needed in addition to their as biosimilar counterparts. As data continues to be gathered in this field, future advancements will optimally decrease the mortality and morbidity of this disease in children.


Subject(s)
Atypical Hemolytic Uremic Syndrome/genetics , Complement Factor H/genetics , Complement Factor I/genetics , Diacylglycerol Kinase/genetics , Mutation , Atypical Hemolytic Uremic Syndrome/drug therapy , Atypical Hemolytic Uremic Syndrome/immunology , Autoantibodies/immunology , COVID-19/genetics , COVID-19/immunology , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/immunology , COVID-19 Vaccines/therapeutic use , Child , Complement Factor H/immunology , Complement Factor I/immunology , Diacylglycerol Kinase/immunology , Humans , SARS-CoV-2/genetics , SARS-CoV-2/immunology , COVID-19 Drug Treatment
4.
iScience ; 24(4): 102290, 2021 Apr 23.
Article in English | MEDLINE | ID: mdl-33870123

ABSTRACT

Single-cell sequencing of environmental microorganisms is an essential component of the microbial ecology toolkit. However, large-scale targeted single-cell sequencing for the whole-genome recovery of uncultivated eukaryotes is lagging. The key challenges are low abundance in environmental communities, large complex genomes, and cell walls that are difficult to break. We describe a pipeline composed of state-of-the art single-cell genomics tools and protocols optimized for poorly studied and uncultivated eukaryotic microorganisms that are found at low abundance. This pipeline consists of seven distinct steps, beginning with sample collection and ending with genome annotation, each equipped with quality review steps to ensure high genome quality at low cost. We tested and evaluated each step on environmental samples and cultures of early-diverging lineages of fungi and Chromista/SAR. We show that genomes produced using this pipeline are almost as good as complete reference genomes for functional and comparative genomics for environmental microbial eukaryotes.

5.
Cochlear Implants Int ; 22(4): 203-215, 2021 07.
Article in English | MEDLINE | ID: mdl-33634749

ABSTRACT

OBJECTIVES: The objectives of this prospective, cross-sectional study were to compare self-perception and communication-success ratings of adolescents with cochlear implant (AWCI) and their caregivers (C-AWCI) and to explore associations with age at CI, implant age, and chronological age. METHOD: Fourteen CI centers across India participated. The Think About it Quiz (TAIQ), Self Assessment of Communication-Adolescent (SAC-A), and Significant Other Assessment of Communication-Adolescent (SOAC-A) were translated into five languages. Data were collected from 173 AWCI aged 10;0-19;6 years and an associated caregiver for each participant. RESULTS: On the TAIQ, self-ratings by AWCI were significantly lower than the ratings by C-AWCI. Peer acceptance correlated with athletic competence for both groups. For the SAC-A versus SOAC-A, there was no significant difference between AWCI and C-AWCI ratings. Except for a negative correlation between peer-acceptance and chronological age for caregiver ratings, no other associations were found between any other ratings and age at CI, implant age, and chronological age. CONCLUSIONS: Caregiver judgments of their adolescents with CI were not in equal agreement with self-ratings by the adolescents across various aspects of performance. Caregivers appeared to underestimate the self-perception issues faced by adolescents with CI but had excellent agreement with their adolescents' self-rating of communication success. The inclusion of activities to improve children's participation in sports could possibly improve peer acceptance.


Subject(s)
Cochlear Implantation , Cochlear Implants , Adolescent , Child , Communication , Cross-Sectional Studies , Humans , Prospective Studies , Self Concept
6.
Nature ; 590(7846): 438-444, 2021 02.
Article in English | MEDLINE | ID: mdl-33505029

ABSTRACT

Long-term climate change and periodic environmental extremes threaten food and fuel security1 and global crop productivity2-4. Although molecular and adaptive breeding strategies can buffer the effects of climatic stress and improve crop resilience5, these approaches require sufficient knowledge of the genes that underlie productivity and adaptation6-knowledge that has been limited to a small number of well-studied model systems. Here we present the assembly and annotation of the large and complex genome of the polyploid bioenergy crop switchgrass (Panicum virgatum). Analysis of biomass and survival among 732 resequenced genotypes, which were grown across 10 common gardens that span 1,800 km of latitude, jointly revealed extensive genomic evidence of climate adaptation. Climate-gene-biomass associations were abundant but varied considerably among deeply diverged gene pools. Furthermore, we found that gene flow accelerated climate adaptation during the postglacial colonization of northern habitats through introgression of alleles from a pre-adapted northern gene pool. The polyploid nature of switchgrass also enhanced adaptive potential through the fractionation of gene function, as there was an increased level of heritable genetic diversity on the nondominant subgenome. In addition to investigating patterns of climate adaptation, the genome resources and gene-trait associations developed here provide breeders with the necessary tools to increase switchgrass yield for the sustainable production of bioenergy.


Subject(s)
Acclimatization/genetics , Biofuels , Genome, Plant/genetics , Genomics , Global Warming , Panicum/genetics , Polyploidy , Biomass , Ecotype , Evolution, Molecular , Gene Flow , Gene Pool , Genetic Introgression , Molecular Sequence Annotation , Panicum/classification , Panicum/growth & development , United States
9.
Sci Rep ; 8(1): 525, 2018 01 11.
Article in English | MEDLINE | ID: mdl-29323202

ABSTRACT

There is a need to clarify relationships within the actinobacterial genus Micromonospora, the type genus of the family Micromonosporaceae, given its biotechnological and ecological importance. Here, draft genomes of 40 Micromonospora type strains and two non-type strains are made available through the Genomic Encyclopedia of Bacteria and Archaea project and used to generate a phylogenomic tree which showed they could be assigned to well supported phyletic lines that were not evident in corresponding trees based on single and concatenated sequences of conserved genes. DNA G+C ratios derived from genome sequences showed that corresponding data from species descriptions were imprecise. Emended descriptions include precise base composition data and approximate genome sizes of the type strains. antiSMASH analyses of the draft genomes show that micromonosporae have a previously unrealised potential to synthesize novel specialized metabolites. Close to one thousand biosynthetic gene clusters were detected, including NRPS, PKS, terpenes and siderophores clusters that were discontinuously distributed thereby opening up the prospect of prioritising gifted strains for natural product discovery. The distribution of key stress related genes provide an insight into how micromonosporae adapt to key environmental variables. Genes associated with plant interactions highlight the potential use of micromonosporae in agriculture and biotechnology.


Subject(s)
Genome, Bacterial , Industrial Microbiology/methods , Micromonospora/genetics , Phylogeny , Base Composition , Micromonospora/classification , Micromonospora/metabolism
10.
New Phytol ; 213(1): 154-169, 2017 01.
Article in English | MEDLINE | ID: mdl-27443672

ABSTRACT

Flowering time is a major determinant of biomass yield in switchgrass (Panicum virgatum), a perennial bioenergy crop, because later flowering allows for an extended period of vegetative growth and increased biomass production. A better understanding of the genetic regulation of flowering time in switchgrass will aid the development of switchgrass varieties with increased biomass yields, particularly at northern latitudes, where late-flowering but southern-adapted varieties have high winter mortality. We use genotypes derived from recently published exome-capture sequencing, which mitigates challenges related to the large, highly repetitive and polyploid switchgrass genome, to perform genome-wide association studies (GWAS) using flowering time data from a switchgrass association panel in an effort to characterize the genetic architecture and genes underlying flowering time regulation in switchgrass. We identify associations with flowering time at multiple loci, including in a homolog of FLOWERING LOCUS T and in a locus containing TIMELESS, a homolog of a key circadian regulator in animals. Our results suggest that flowering time variation in switchgrass is due to variation at many positions across the genome. The relationship of flowering time and geographic origin indicates likely roles for genes in the photoperiod and autonomous pathways in generating switchgrass flowering time variation.


Subject(s)
Exome Sequencing/methods , Exome/genetics , Flowers/genetics , Flowers/physiology , Genome-Wide Association Study , Panicum/genetics , Alleles , Genes, Plant , Genetic Association Studies , Genetic Variation , Genotype , Geography , Linkage Disequilibrium/genetics , Phenotype , Seasons , Temperature , Time Factors
11.
J Voice ; 31(3): 391.e19-391.e25, 2017 May.
Article in English | MEDLINE | ID: mdl-28029557

ABSTRACT

OBJECTIVE: The purpose of this study was to investigate the duration required by children with cochlear implants to approximate the norms of voice acoustic parameters. STUDY DESIGN: The study design is retrospective. METHODS: Thirty children with cochlear implants (chronological ages ranging between 4.1 and 6.7 years) were divided into three groups, based on the postimplantation duration. Ten normal-hearing children (chronological ages ranging between 4 and 7 years) were selected as the control group. All implanted children underwent an objective voice analysis using Dr. Speech software (Tiger DRS, Inc., Seattle, WA, USA) at 6 months and at 1 and 2 years of implant use. Voice analysis was done for the children in the control group and means were derived for all the parameters analyzed to obtain the normal values. Habitual fundamental frequency (HFF), jitter (frequency variation), and shimmer (amplitude variation) were the voice acoustic parameters analyzed for the vowels |a|, |i|, and |u|. The obtained values of these parameters were then compared with the norms. RESULTS: HFF for the children with implant use for 6 months and 1 year did significantly differ from the control group. However, there was no significant difference (P > 0.5) observed in the children with implant use for 2 years, thus matching the norms. Jitter and shimmer showed a significant difference (P < 0.5) even at 2 years of implant use when compared with the control group. CONCLUSIONS: The findings of the study divulge that children with cochlear implants approximate age-matched normal-hearing kids with respect to the voice acoustic parameter of HFF by 2 years of implant use. However, jitter and shimmer were not found to stabilize for the duration studied.


Subject(s)
Cochlear Implantation/instrumentation , Cochlear Implants , Persons With Hearing Impairments/rehabilitation , Speech Acoustics , Speech Perception , Voice Quality , Acoustic Stimulation , Acoustics , Adaptation, Psychological , Child , Child, Preschool , Electric Stimulation , Female , Humans , India , Male , Persons With Hearing Impairments/psychology , Phonation , Retrospective Studies , Signal Processing, Computer-Assisted , Speech Production Measurement , Time Factors
12.
Sci Data ; 3: 160081, 2016 Sep 27.
Article in English | MEDLINE | ID: mdl-27673566

ABSTRACT

Generating sequence data of a defined community composed of organisms with complete reference genomes is indispensable for the benchmarking of new genome sequence analysis methods, including assembly and binning tools. Moreover the validation of new sequencing library protocols and platforms to assess critical components such as sequencing errors and biases relies on such datasets. We here report the next generation metagenomic sequence data of a defined mock community (Mock Bacteria ARchaea Community; MBARC-26), composed of 23 bacterial and 3 archaeal strains with finished genomes. These strains span 10 phyla and 14 classes, a range of GC contents, genome sizes, repeat content and encompass a diverse abundance profile. Short read Illumina and long-read PacBio SMRT sequences of this mock community are described. These data represent a valuable resource for the scientific community, enabling extensive benchmarking and comparative evaluation of bioinformatics tools without the need to simulate data. As such, these data can aid in improving our current sequence data analysis toolkit and spur interest in the development of new tools.

13.
Proc Natl Acad Sci U S A ; 113(35): 9882-7, 2016 08 30.
Article in English | MEDLINE | ID: mdl-27535936

ABSTRACT

Ascomycete yeasts are metabolically diverse, with great potential for biotechnology. Here, we report the comparative genome analysis of 29 taxonomically and biotechnologically important yeasts, including 16 newly sequenced. We identify a genetic code change, CUG-Ala, in Pachysolen tannophilus in the clade sister to the known CUG-Ser clade. Our well-resolved yeast phylogeny shows that some traits, such as methylotrophy, are restricted to single clades, whereas others, such as l-rhamnose utilization, have patchy phylogenetic distributions. Gene clusters, with variable organization and distribution, encode many pathways of interest. Genomics can predict some biochemical traits precisely, but the genomic basis of others, such as xylose utilization, remains unresolved. Our data also provide insight into early evolution of ascomycetes. We document the loss of H3K9me2/3 heterochromatin, the origin of ascomycete mating-type switching, and panascomycete synteny at the MAT locus. These data and analyses will facilitate the engineering of efficient biosynthetic and degradative pathways and gateways for genomic manipulation.


Subject(s)
Biotechnology/methods , Genome, Fungal/genetics , Genomics/methods , Yeasts/genetics , Ascomycota/classification , Ascomycota/genetics , Ascomycota/metabolism , Evolution, Molecular , Fungal Proteins/genetics , Fungal Proteins/metabolism , Genetic Code/genetics , Metabolic Networks and Pathways/genetics , Phylogeny , Species Specificity , Yeasts/classification , Yeasts/metabolism
14.
Cochlear Implants Int ; 17(4): 207-210, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27251776

ABSTRACT

OBJECTIVE: Cochlear implantation is routinely performed under general anaesthesia in most centres in the world. There have been reports of this surgery being performed under local anaesthesia and sedation for unilateral cochlear implantation. Our case study reports the first bilateral cochlear implantation carried out under local anaesthesia with sedation. This paper outlines the protocol used and discusses the challenges and advantages of the procedure being performed under local anaesthesia. CASE STUDY: A 28-year-old female with a history of multidrug-resistant tuberculosis presented with bilateral severe to profound sensorineural hearing loss. On evaluation, she was found to be a suitable candidate for cochlear implantation. However, she was clinically unfit to undergo the surgery under general anaesthesia. After counselling the patient, the decision to undertake the procedure under local anaesthesia was made. The procedure took 105 min and was uneventful. The patient was discharged the next day Conclusion: In the hands of an experienced surgeon and anaesthesiology team, bilateral cochlear implantation is possible under local anaesthesia. Patient motivation and cooperation are extremely important for the procedure to be done under local anaesthesia. This is an option for patients needing cochlear implantation who are medically unfit for general anaesthesia.


Subject(s)
Anesthesia, Local/methods , Cochlear Implantation/methods , Hearing Loss, Bilateral/surgery , Hearing Loss, Sensorineural/surgery , Adult , Anesthesia, General , Contraindications , Female , Hearing Loss, Bilateral/microbiology , Hearing Loss, Sensorineural/microbiology , Humans , Treatment Outcome , Tuberculosis, Multidrug-Resistant/complications
15.
mBio ; 6(4): e00918, 2015 Jul 21.
Article in English | MEDLINE | ID: mdl-26199329

ABSTRACT

UNLABELLED: Microbial fermentation of agro-industrial waste holds great potential for reducing the environmental impact associated with the production of lipids for industrial purposes from plant biomass. However, the chemical complexity of many residues currently prevents efficient conversion into lipids, creating a high demand for strains with the ability to utilize all energy-rich components of agricultural residues. Here, we present results of genome and transcriptome analyses of Trichosporon oleaginosus. This oil-accumulating yeast is able to grow on a wide variety of substrates, including pentoses and N-acetylglucosamine, making it an interesting candidate for biotechnological applications. Transcriptomics shows specific changes in gene expression patterns under lipid-accumulating conditions. Furthermore, gene content and expression analyses indicate that T. oleaginosus is well-adapted for the utilization of chitin-rich biomass. We also focused on the T. oleaginosus mating type, because this species is a member of the Tremellomycetes, a group that has been intensively analyzed as a model for the evolution of sexual development, the best-studied member being Cryptococcus neoformans. The structure of the T. oleaginosus mating-type regions differs significantly from that of other Tremellomycetes and reveals a new evolutionary trajectory paradigm. Comparative analysis shows that recruitment of developmental genes to the ancestral tetrapolar mating-type loci occurred independently in the Trichosporon and Cryptococcus lineages, supporting the hypothesis of a trend toward larger mating-type regions in fungi. IMPORTANCE: Finite fossil fuel resources pose sustainability challenges to society and industry. Microbial oils are a sustainable feedstock for biofuel and chemical production that does not compete with food production. We describe genome and transcriptome analyses of the oleaginous yeast Trichosporon oleaginosus, which can accumulate up to 70% of its dry weight as lipids. In contrast to conventional yeasts, this organism not only shows an absence of diauxic effect while fermenting hexoses and pentoses but also effectively utilizes xylose and N-acetylglucosamine, which are building blocks of lignocellulose and chitin, respectively. Transcriptome analysis revealed metabolic networks that govern conversion of xylose or N-acetylglucosamine as well as lipid accumulation. These data form the basis for a targeted strain optimization strategy. Furthermore, analysis of the mating type of T. oleaginosus supports the hypothesis of a trend toward larger mating-type regions in fungi, similar to the evolution of sex chromosomes in animals and plants.


Subject(s)
Gene Expression Profiling , Genes, Mating Type, Fungal , Lipid Metabolism , Metabolic Networks and Pathways , Trichosporon/genetics , Trichosporon/metabolism , Biomass , DNA, Fungal/chemistry , DNA, Fungal/genetics , Evolution, Molecular , Molecular Sequence Data , Plants/chemistry , Sequence Analysis, DNA
16.
G3 (Bethesda) ; 5(8): 1593-602, 2015 Jun 01.
Article in English | MEDLINE | ID: mdl-26038364

ABSTRACT

Delayed transition from the vegetative stage to the reproductive stage of development and increased plant height have been shown to increase biomass productivity in grasses. The goal of this project was to detect quantitative trait loci using extremes from a large synthetic population, as well as a related recombinant inbred line mapping population for these two traits. Ten thousand individuals from a B73 × Mo17 noninbred population intermated for 14 generations (IBM Syn14) were grown at a density of approximately 16,500 plants ha(-1). Flowering time and plant height were measured within this population. DNA was pooled from the 46 most extreme individuals from each distributional tail for each of the traits measured and used in bulk segregant analysis (BSA) sequencing. Allelic divergence at each of the ∼1.1 million SNP loci was estimated as the difference in allele frequencies between the selected extremes. Additionally, 224 intermated B73 × Mo17 recombinant inbred lines were concomitantly grown at a similar density adjacent to the large synthetic population and were assessed for flowering time and plant height. Using the BSA sequencing method, 14 and 13 genomic regions were identified for flowering time and plant height, respectively. Linkage mapping with the RIL population identified eight and three regions for flowering time and plant height, respectively. Of the regions identified, three colocalized between the two populations for flowering time and two colocalized for plant height. This study demonstrates the utility of using BSA sequencing for the dissection of complex quantitative traits important for production of lignocellulosic ethanol.


Subject(s)
Genome, Plant/drug effects , Zea mays/genetics , Alleles , Chromosome Mapping , Chromosomes, Plant , DNA, Plant/chemistry , DNA, Plant/metabolism , Flowers/metabolism , Gene Frequency , Genetic Linkage , Phenotype , Polymorphism, Single Nucleotide , Quantitative Trait Loci , Sequence Analysis, DNA , Zea mays/growth & development
17.
Genome Biol Evol ; 6(9): 2557-66, 2014 Sep.
Article in English | MEDLINE | ID: mdl-25364804

ABSTRACT

Lignocellulosic plant material is a viable source of biomass to produce alternative energy including ethanol and other biofuels. However, several factors­including toxic by products from biomass pretreatment and poor fermentation of xylose and other pentose sugars­currently limit the efficiency of microbial biofuel production. To begin to understand the genetic basis of desirable traits, we characterized three strains of Saccharomyces cerevisiae with robust growth in a pretreated lignocellulosic hydrolysate or tolerance to stress conditions relevant to industrial biofuel production, through genome and transcriptome sequencing analysis. All stress resistant strains were highly mosaic, suggesting that genetic admixture may contribute to novel allele combinations underlying these phenotypes. Strain-specific gene sets not found in the lab strain were functionally linked to the tolerances of particular strains. Furthermore,genes with signatures of evolutionary selection were enriched for functional categories important for stress resistance and included stress-responsive signaling factors. Comparison of the strains' transcriptomic responses to heat and ethanol treatment­two stresses relevant to industrial bioethanol production­pointed to physiological processes that were related to particular stress resistance profiles. Many of the genotype-by-environment expression responses occurred at targets of transcription factors with signatures of positive selection, suggesting that these strains have undergone positive selection for stress tolerance. Our results generate new insights into potential mechanisms of tolerance to stresses relevant to biofuel production, including ethanol and heat, present a backdrop for further engineering, and provide glimpses into the natural variation of stress tolerance in wild yeast strains.


Subject(s)
Ethanol/metabolism , Genome, Fungal , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Energy Metabolism , Fermentation , Genomics , Polymorphism, Single Nucleotide , Saccharomyces cerevisiae/growth & development
18.
Genetics ; 198(1): 409-21, 2014 Sep.
Article in English | MEDLINE | ID: mdl-25037958

ABSTRACT

Grain produced from cereal crops is a primary source of human food and animal feed worldwide. To understand the genetic basis of seed-size variation, a grain yield component, we conducted a genome-wide scan to detect evidence of selection in the maize Krug Yellow Dent long-term divergent seed-size selection experiment. Previous studies have documented significant phenotypic divergence between the populations. Allele frequency estimates for ∼3 million single nucleotide polymorphisms (SNPs) in the base population and selected populations were estimated from pooled whole-genome resequencing of 48 individuals per population. Using FST values across sliding windows, 94 divergent regions with a median of six genes per region were identified. Additionally, 2729 SNPs that reached fixation in both selected populations with opposing fixed alleles were identified, many of which clustered in two regions of the genome. Copy-number variation was highly prevalent between the selected populations, with 532 total regions identified on the basis of read-depth variation and comparative genome hybridization. Regions important for seed weight in natural variation were identified in the maize nested association mapping population. However, the number of regions that overlapped with the long-term selection experiment did not exceed that expected by chance, possibly indicating unique sources of variation between the two populations. The results of this study provide insights into the genetic elements underlying seed-size variation in maize and could also have applications for other cereal crops.


Subject(s)
Seeds/genetics , Selection, Genetic , Zea mays/genetics , DNA Copy Number Variations , Gene Frequency , Genome, Plant , Models, Genetic , Polymorphism, Single Nucleotide , Quantitative Trait, Heritable , Seeds/anatomy & histology , Zea mays/growth & development
19.
Genetics ; 196(3): 829-40, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24381334

ABSTRACT

A genome-wide scan to detect evidence of selection was conducted in the Golden Glow maize long-term selection population. The population had been subjected to selection for increased number of ears per plant for 30 generations, with an empirically estimated effective population size ranging from 384 to 667 individuals and an increase of more than threefold in the number of ears per plant. Allele frequencies at >1.2 million single-nucleotide polymorphism loci were estimated from pooled whole-genome resequencing data, and FST values across sliding windows were employed to assess divergence between the population preselection and the population postselection. Twenty-eight highly divergent regions were identified, with half of these regions providing gene-level resolution on potentially selected variants. Approximately 93% of the divergent regions do not demonstrate a significant decrease in heterozygosity, which suggests that they are not approaching fixation. Also, most regions display a pattern consistent with a soft-sweep model as opposed to a hard-sweep model, suggesting that selection mostly operated on standing genetic variation. For at least 25% of the regions, results suggest that selection operated on variants located outside of currently annotated coding regions. These results provide insights into the underlying genetic effects of long-term artificial selection and identification of putative genetic elements underlying number of ears per plant in maize.


Subject(s)
Genome, Plant , Selection, Genetic , Zea mays/genetics , Chromosomes, Plant , Gene Frequency , Genetic Heterogeneity , Genetic Variation , Phenotype , Polymorphism, Single Nucleotide
20.
Appl Environ Microbiol ; 80(2): 540-54, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24212571

ABSTRACT

The fermentation of lignocellulose-derived sugars, particularly xylose, into ethanol by the yeast Saccharomyces cerevisiae is known to be inhibited by compounds produced during feedstock pretreatment. We devised a strategy that combined chemical profiling of pretreated feedstocks, high-throughput phenotyping of genetically diverse S. cerevisiae strains isolated from a range of ecological niches, and directed engineering and evolution against identified inhibitors to produce strains with improved fermentation properties. We identified and quantified for the first time the major inhibitory compounds in alkaline hydrogen peroxide (AHP)-pretreated lignocellulosic hydrolysates, including Na(+), acetate, and p-coumaric (pCA) and ferulic (FA) acids. By phenotyping these yeast strains for their abilities to grow in the presence of these AHP inhibitors, one heterozygous diploid strain tolerant to all four inhibitors was selected, engineered for xylose metabolism, and then allowed to evolve on xylose with increasing amounts of pCA and FA. After only 149 generations, one evolved isolate, GLBRCY87, exhibited faster xylose uptake rates in both laboratory media and AHP switchgrass hydrolysate than its ancestral GLBRCY73 strain and completely converted 115 g/liter of total sugars in undetoxified AHP hydrolysate into more than 40 g/liter ethanol. Strikingly, genome sequencing revealed that during the evolution from GLBRCY73, the GLBRCY87 strain acquired the conversion of heterozygous to homozygous alleles in chromosome VII and amplification of chromosome XIV. Our approach highlights that simultaneous selection on xylose and pCA or FA with a wild S. cerevisiae strain containing inherent tolerance to AHP pretreatment inhibitors has potential for rapid evolution of robust properties in lignocellulosic biofuel production.


Subject(s)
Ethanol/metabolism , Genetic Engineering/methods , Genetic Variation , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Xylose/metabolism , Biomass , Chromosomes, Fungal , Coumaric Acids/metabolism , Fermentation , Hydrogen Peroxide/pharmacology , Hydrolysis , Industrial Microbiology/methods , Lignin , Loss of Heterozygosity , Panicum/drug effects , Propionates
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