Publications by authors named "Fengtang Yang"

141 Publications

Werner helicase is a synthetic-lethal vulnerability in Mismatch Repair-Deficient Colorectal Cancer Refractory to Targeted Therapies, Chemotherapy and Immunotherapy.

Cancer Discov 2021 Apr 9. Epub 2021 Apr 9.

Cancer Programme, Wellcome Sanger Institute

Targeted therapies, chemotherapy, and immunotherapy are used to treat patients with mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) colorectal cancer (CRC). The clinical effectiveness of targeted therapy and chemotherapy is limited by resistance and drug toxicities, and about half of immunotherapy patients are refractory to immune checkpoint inhibitors. Loss of Werner syndrome ATP-dependent helicase (WRN) is a synthetic-lethality in dMMR/MSI-H cells. To inform the development of WRN as a therapeutic target, we performed WRN knockout or knockdown in 60 heterogeneous dMMR CRC preclinical models, demonstrating that WRN dependency is an almost universal feature and a robust marker for patient selection. Furthermore, models of resistance to clinically relevant targeted therapy, chemotherapy, and immunotherapy retain WRN dependency. These data show the potential of therapeutically targeting WRN in dMMR/MSI-H CRC patients, and support WRN as a therapeutic option for patients with dMMR/MSI-H cancers refractory to current treatment strategies.
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http://dx.doi.org/10.1158/2159-8290.CD-20-1508DOI Listing
April 2021

Analysis of multiple chromosomal rearrangements in the genome of Willisornis vidua using BAC-FISH and chromosome painting on a supposed conserved karyotype.

BMC Ecol Evol 2021 03 2;21(1):34. Epub 2021 Mar 2.

School of Biosciences, University of Kent, Canterbury, UK.

Background: Thamnophilidae birds are the result of a monophyletic radiation of insectivorous Passeriformes. They are a diverse group of 225 species and 45 genera and occur in lowlands and lower montane forests of Neotropics. Despite the large degree of diversity seen in this family, just four species of Thamnophilidae have been karyotyped with a diploid number ranging from 76 to 82 chromosomes. The karyotypic relationships within and between Thamnophilidae and another Passeriformes therefore remain poorly understood. Recent studies have identified the occurrence of intrachromosomal rearrangements in Passeriformes using in silico data and molecular cytogenetic tools. These results demonstrate that intrachromosomal rearrangements are more common in birds than previously thought and are likely to contribute to speciation events. With this in mind, we investigate the apparently conserved karyotype of Willisornis vidua, the Xingu Scale-backed Antbird, using a combination of molecular cytogenetic techniques including chromosome painting with probes derived from Gallus gallus (chicken) and Burhinus oedicnemus (stone curlew), combined with Bacterial Artificial Chromosome (BAC) probes derived from the same species. The goal was to investigate the occurrence of rearrangements in an apparently conserved karyotype in order to understand the evolutionary history and taxonomy of this species. In total, 78 BAC probes from the Gallus gallus and Taeniopygia guttata (the Zebra Finch) BAC libraries were tested, of which 40 were derived from Gallus gallus macrochromosomes 1-8, and 38 from microchromosomes 9-28.

Results: The karyotype is similar to typical Passeriformes karyotypes, with a diploid number of 2n = 80. Our chromosome painting results show that most of the Gallus gallus chromosomes are conserved, except GGA-1, 2 and 4, with some rearrangements identified among macro- and microchromosomes. BAC mapping revealed many intrachromosomal rearrangements, mainly inversions, when comparing Willisornis vidua karyotype with Gallus gallus, and corroborates the fissions revealed by chromosome painting.

Conclusions: Willisornis vidua presents multiple chromosomal rearrangements despite having a supposed conservative karyotype, demonstrating that our approach using a combination of FISH tools provides a higher resolution than previously obtained by chromosome painting alone. We also show that populations of Willisornis vidua appear conserved from a cytogenetic perspective, despite significant phylogeographic structure.
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http://dx.doi.org/10.1186/s12862-021-01768-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7927240PMC
March 2021

Combinatorial CRISPR screen identifies fitness effects of gene paralogues.

Nat Commun 2021 02 26;12(1):1302. Epub 2021 Feb 26.

Wellcome Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK.

Genetic redundancy has evolved as a way for human cells to survive the loss of genes that are single copy and essential in other organisms, but also allows tumours to survive despite having highly rearranged genomes. In this study we CRISPR screen 1191 gene pairs, including paralogues and known and predicted synthetic lethal interactions to identify 105 gene combinations whose co-disruption results in a loss of cellular fitness. 27 pairs influence fitness across multiple cell lines including the paralogues FAM50A/FAM50B, two genes of unknown function. Silencing of FAM50B occurs across a range of tumour types and in this context disruption of FAM50A reduces cellular fitness whilst promoting micronucleus formation and extensive perturbation of transcriptional programmes. Our studies reveal the fitness effects of FAM50A/FAM50B in cancer cells.
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http://dx.doi.org/10.1038/s41467-021-21478-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7910459PMC
February 2021

Chromosomal painting of the sandpiper (Actitis macularius) detects several fissions for the Scolopacidae family (Charadriiformes).

BMC Ecol Evol 2021 01 22;21(1). Epub 2021 Jan 22.

Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, ICB, Universidade Federal do Pará, PCT-Guamá, Terreno 11, Belém, Pará, 66075-750, Brazil.

Background: The Scolopacidae family (Suborder Scolopaci, Charadriiformes) is composed of sandpipers and snipes; these birds are long-distance migrants that show great diversity in their behavior and habitat use. Cytogenetic studies in the Scolopacidae family show the highest diploid numbers for order Charadriiformes. This work analyzes for the first time the karyotype of Actitis macularius by classic cytogenetics and chromosome painting.

Results: The species has a diploid number of 92, composed mostly of telocentric pairs. This high 2n is greater than the proposed 80 for the avian ancestral putative karyotype (a common feature among Scolopaci), suggesting that fission rearrangements have formed smaller macrochromosomes and microchromosomes. Fluorescence in situ hybridization using Burhinus oedicnemus whole chromosome probes confirmed the fissions in pairs 1, 2, 3, 4 and 6 of macrochromosomes.

Conclusion: Comparative analysis with other species of Charadriiformes studied by chromosome painting together with the molecular phylogenies for the order allowed us to raise hypotheses about the chromosomal evolution in suborder Scolopaci. From this, we can establish a clear idea of how chromosomal evolution occurred in this suborder.
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http://dx.doi.org/10.1186/s12862-020-01737-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7853317PMC
January 2021

Evidence for multi-copy Mega-NUMTs in the human genome.

Nucleic Acids Res 2021 02;49(3):1517-1531

Institute of Legal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria.

The maternal mode of mitochondrial DNA (mtDNA) inheritance is central to human genetics. Recently, evidence for bi-parental inheritance of mtDNA was claimed for individuals of three pedigrees that suffered mitochondrial disorders. We sequenced mtDNA using both direct Sanger and Massively Parallel Sequencing in several tissues of eleven maternally related and other affiliated healthy individuals of a family pedigree and observed mixed mitotypes in eight individuals. Cells without nuclear DNA, i.e. thrombocytes and hair shafts, only showed the mitotype of haplogroup (hg) V. Skin biopsies were prepared to generate ρ° cells void of mtDNA, sequencing of which resulted in a hg U4c1 mitotype. The position of the Mega-NUMT sequence was determined by fluorescence in situ hybridization and two different quantitative PCR assays were used to determine the number of contributing mtDNA copies. Thus, evidence for the presence of repetitive, full mitogenome Mega-NUMTs matching haplogroup U4c1 in various tissues of eight maternally related individuals was provided. Multi-copy Mega-NUMTs mimic mixtures of mtDNA that cannot be experimentally avoided and thus may appear in diverse fields of mtDNA research and diagnostics. We demonstrate that hair shaft mtDNA sequencing provides a simple but reliable approach to exclude NUMTs as source of misleading results.
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http://dx.doi.org/10.1093/nar/gkaa1271DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7897518PMC
February 2021

PiggyBac mutagenesis and exome sequencing identify genetic driver landscapes and potential therapeutic targets of EGFR-mutant gliomas.

Genome Biol 2020 07 30;21(1):181. Epub 2020 Jul 30.

The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, CB10 1SA, UK.

Background: Glioma is the most common intrinsic brain tumor and also occurs in the spinal cord. Activating EGFR mutations are common in IDH1 wild-type gliomas. However, the cooperative partners of EGFR driving gliomagenesis remain poorly understood.

Results: We explore EGFR-mutant glioma evolution in conditional mutant mice by whole-exome sequencing, transposon mutagenesis forward genetic screening, and transcriptomics. We show mutant EGFR is sufficient to initiate gliomagenesis in vivo, both in the brain and spinal cord. We identify significantly recurrent somatic alterations in these gliomas including mutant EGFR amplifications and Sub1, Trp53, and Tead2 loss-of-function mutations. Comprehensive functional characterization of 96 gliomas by genome-wide piggyBac insertional mutagenesis in vivo identifies 281 known and novel EGFR-cooperating driver genes, including Cdkn2a, Nf1, Spred1, and Nav3. Transcriptomics confirms transposon-mediated effects on expression of these genes. We validate the clinical relevance of new putative tumor suppressors by showing these are frequently altered in patients' gliomas, with prognostic implications. We discover shared and distinct driver mutations in brain and spinal gliomas and confirm in vivo differential tumor suppressive effects of Pten between these tumors. Functional validation with CRISPR-Cas9-induced mutations in novel genes Tead2, Spred1, and Nav3 demonstrates heightened EGFRvIII-glioma cell proliferation. Chemogenomic analysis of mutated glioma genes reveals potential drug targets, with several investigational drugs showing efficacy in vitro.

Conclusion: Our work elucidates functional driver landscapes of EGFR-mutant gliomas, uncovering potential therapeutic strategies, and provides new tools for functional interrogation of gliomagenesis.
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http://dx.doi.org/10.1186/s13059-020-02092-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7392733PMC
July 2020

Structural variation of the malaria-associated human glycophorin A-B-E region.

BMC Genomics 2020 Jun 29;21(1):446. Epub 2020 Jun 29.

Department of Genetics and Genome Biology, University of Leicester, Leicester, UK.

Background: Approximately 5% of the human genome shows common structural variation, which is enriched for genes involved in the immune response and cell-cell interactions. A well-established region of extensive structural variation is the glycophorin gene cluster, comprising three tandemly-repeated regions about 120 kb in length and carrying the highly homologous genes GYPA, GYPB and GYPE. Glycophorin A (encoded by GYPA) and glycophorin B (encoded by GYPB) are glycoproteins present at high levels on the surface of erythrocytes, and they have been suggested to act as decoy receptors for viral pathogens. They are receptors for the invasion of the protist parasite Plasmodium falciparum, a causative agent of malaria. A particular complex structural variant, called DUP4, creates a GYPB-GYPA fusion gene known to confer resistance to malaria. Many other structural variants exist across the glycophorin gene cluster, and they remain poorly characterised.

Results: Here, we analyse sequences from 3234 diploid genomes from across the world for structural variation at the glycophorin locus, confirming 15 variants in the 1000 Genomes project cohort, discovering 9 new variants, and characterising a selection of these variants using fibre-FISH and breakpoint mapping at the sequence level. We identify variants predicted to create novel fusion genes and a common inversion duplication variant at appreciable frequencies in West Africans. We show that almost all variants can be explained by non-allelic homologous recombination and by comparing the structural variant breakpoints with recombination hotspot maps, confirm the importance of a particular meiotic recombination hotspot on structural variant formation in this region.

Conclusions: We identify and validate large structural variants in the human glycophorin A-B-E gene cluster which may be associated with different clinical aspects of malaria.
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http://dx.doi.org/10.1186/s12864-020-06849-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7325229PMC
June 2020

Population Structure, Stratification, and Introgression of Human Structural Variation.

Cell 2020 07 11;182(1):189-199.e15. Epub 2020 Jun 11.

Wellcome Sanger Institute, Hinxton CB10 1SA, UK. Electronic address:

Structural variants contribute substantially to genetic diversity and are important evolutionarily and medically, but they are still understudied. Here we present a comprehensive analysis of structural variation in the Human Genome Diversity panel, a high-coverage dataset of 911 samples from 54 diverse worldwide populations. We identify, in total, 126,018 variants, 78% of which were not identified in previous global sequencing projects. Some reach high frequency and are private to continental groups or even individual populations, including regionally restricted runaway duplications and putatively introgressed variants from archaic hominins. By de novo assembly of 25 genomes using linked-read sequencing, we discover 1,643 breakpoint-resolved unique insertions, in aggregate accounting for 1.9 Mb of sequence absent from the GRCh38 reference. Our results illustrate the limitation of a single human reference and the need for high-quality genomes from diverse populations to fully discover and understand human genetic variation.
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http://dx.doi.org/10.1016/j.cell.2020.05.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7369638PMC
July 2020

Analysis pipelines for cancer genome sequencing in mice.

Nat Protoc 2020 02 6;15(2):266-315. Epub 2020 Jan 6.

Institute of Molecular Oncology and Functional Genomics, School of Medicine, Technische Universität München, Munich, Germany.

Mouse models of human cancer have transformed our ability to link genetics, molecular mechanisms and phenotypes. Both reverse and forward genetics in mice are currently gaining momentum through advances in next-generation sequencing (NGS). Methodologies to analyze sequencing data were, however, developed for humans and hence do not account for species-specific differences in genome structures and experimental setups. Here, we describe standardized computational pipelines specifically tailored to the analysis of mouse genomic data. We present novel tools and workflows for the detection of different alteration types, including single-nucleotide variants (SNVs), small insertions and deletions (indels), copy-number variations (CNVs), loss of heterozygosity (LOH) and complex rearrangements, such as in chromothripsis. Workflows have been extensively validated and cross-compared using multiple methodologies. We also give step-by-step guidance on the execution of individual analysis types, provide advice on data interpretation and make the complete code available online. The protocol takes 2-7 d, depending on the desired analyses.
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http://dx.doi.org/10.1038/s41596-019-0234-7DOI Listing
February 2020

Chromosome-level genome assembly for giant panda provides novel insights into Carnivora chromosome evolution.

Genome Biol 2019 12 6;20(1):267. Epub 2019 Dec 6.

CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

Background: Chromosome evolution is an important driver of speciation and species evolution. Previous studies have detected chromosome rearrangement events among different Carnivora species using chromosome painting strategies. However, few of these studies have focused on chromosome evolution at a nucleotide resolution due to the limited availability of chromosome-level Carnivora genomes. Although the de novo genome assembly of the giant panda is available, current short read-based assemblies are limited to moderately sized scaffolds, making the study of chromosome evolution difficult.

Results: Here, we present a chromosome-level giant panda draft genome with a total size of 2.29 Gb. Based on the giant panda genome and published chromosome-level dog and cat genomes, we conduct six large-scale pairwise synteny alignments and identify evolutionary breakpoint regions. Interestingly, gene functional enrichment analysis shows that for all of the three Carnivora genomes, some genes located in evolutionary breakpoint regions are significantly enriched in pathways or terms related to sensory perception of smell. In addition, we find that the sweet receptor gene TAS1R2, which has been proven to be a pseudogene in the cat genome, is located in an evolutionary breakpoint region of the giant panda, suggesting that interchromosomal rearrangement may play a role in the cat TAS1R2 pseudogenization.

Conclusions: We show that the combined strategies employed in this study can be used to generate efficient chromosome-level genome assemblies. Moreover, our comparative genomics analyses provide novel insights into Carnivora chromosome evolution, linking chromosome evolution to functional gene evolution.
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http://dx.doi.org/10.1186/s13059-019-1889-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6898958PMC
December 2019

Birth, expansion, and death of VCY-containing palindromes on the human Y chromosome.

Genome Biol 2019 10 14;20(1):207. Epub 2019 Oct 14.

The Wellcome Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK.

Background: Large palindromes (inverted repeats) make up substantial proportions of mammalian sex chromosomes, often contain genes, and have high rates of structural variation arising via ectopic recombination. As a result, they underlie many genomic disorders. Maintenance of the palindromic structure by gene conversion between the arms has been documented, but over longer time periods, palindromes are remarkably labile. Mechanisms of origin and loss of palindromes have, however, received little attention.

Results: Here, we use fiber-FISH, 10x Genomics Linked-Read sequencing, and breakpoint PCR sequencing to characterize the structural variation of the P8 palindrome on the human Y chromosome, which contains two copies of the VCY (Variable Charge Y) gene. We find a deletion of almost an entire arm of the palindrome, leading to death of the palindrome, a size increase by recruitment of adjacent sequence, and other complex changes including the formation of an entire new palindrome nearby. Together, these changes are found in ~ 1% of men, and we can assign likely molecular mechanisms to these mutational events. As a result, healthy men can have 1-4 copies of VCY.

Conclusions: Gross changes, especially duplications, in palindrome structure can be relatively frequent and facilitate the evolution of sex chromosomes in humans, and potentially also in other mammalian species.
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http://dx.doi.org/10.1186/s13059-019-1816-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6790999PMC
October 2019

A new patient-derived iPSC model for dystroglycanopathies validates a compound that increases glycosylation of α-dystroglycan.

EMBO Rep 2019 11 30;20(11):e47967. Epub 2019 Sep 30.

Centre for Genomics and Child Health, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.

Dystroglycan, an extracellular matrix receptor, has essential functions in various tissues. Loss of α-dystroglycan-laminin interaction due to defective glycosylation of α-dystroglycan underlies a group of congenital muscular dystrophies often associated with brain malformations, referred to as dystroglycanopathies. The lack of isogenic human dystroglycanopathy cell models has limited our ability to test potential drugs in a human- and neural-specific context. Here, we generated induced pluripotent stem cells (iPSCs) from a severe dystroglycanopathy patient with homozygous FKRP (fukutin-related protein gene) mutation. We showed that CRISPR/Cas9-mediated gene correction of FKRP restored glycosylation of α-dystroglycan in iPSC-derived cortical neurons, whereas targeted gene mutation of FKRP in wild-type cells disrupted this glycosylation. In parallel, we screened 31,954 small molecule compounds using a mouse myoblast line for increased glycosylation of α-dystroglycan. Using human FKRP-iPSC-derived neural cells for hit validation, we demonstrated that compound 4-(4-bromophenyl)-6-ethylsulfanyl-2-oxo-3,4-dihydro-1H-pyridine-5-carbonitrile (4BPPNit) significantly augmented glycosylation of α-dystroglycan, in part through upregulation of LARGE1 glycosyltransferase gene expression. Together, isogenic human iPSC-derived cells represent a valuable platform for facilitating dystroglycanopathy drug discovery and therapeutic development.
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http://dx.doi.org/10.15252/embr.201947967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6832011PMC
November 2019

Expanded potential stem cell media as a tool to study human developmental hematopoiesis in vitro.

Exp Hematol 2019 08 18;76:1-12.e5. Epub 2019 Jul 18.

Department of Haematology, Wellcome & MRC Cambridge Stem Cell Institute, Cambridge, UK. Electronic address:

Pluripotent stem cell (PSC) differentiation in vitro represents a powerful and tractable model to study mammalian development and an unlimited source of cells for regenerative medicine. Within hematology, in vitro PSC hematopoiesis affords novel insights into blood formation and represents an exciting potential approach to generate hematopoietic and immune cell types for transplantation and transfusion. Most studies to date have focused on in vitro hematopoiesis from mouse PSCs and human PSCs. However, differences in mouse and human PSC culture protocols have complicated the translation of discoveries between these systems. We recently developed a novel chemical media formulation, expanded potential stem cell medium (EPSCM), that maintains mouse PSCs in a unique cellular state and extraembryonic differentiation capacity. Herein, we describe how EPSCM can be directly used to stably maintain human PSCs. We further demonstrate that human PSCs maintained in EPSCM can spontaneously form embryoid bodies and undergo in vitro hematopoiesis using a simple differentiation protocol, similar to mouse PSC differentiation. EPSCM-maintained human PSCs generated at least two hematopoietic cell populations, which displayed distinct transcriptional profiles by RNA-sequencing (RNA-seq) analysis. EPSCM also supports gene targeting using homologous recombination, affording generation of an SPI1 (PU.1) reporter PSC line to study and track in vitro hematopoiesis. EPSCM therefore provides a useful tool not only to study pluripotency but also hematopoietic cell specification and developmental-lineage commitment.
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http://dx.doi.org/10.1016/j.exphem.2019.07.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6859476PMC
August 2019

Derivation and maintenance of mouse haploid embryonic stem cells.

Nat Protoc 2019 07 3;14(7):1991-2014. Epub 2019 Jun 3.

UK Dementia Research Institute at University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.

Ploidy represents the number of chromosome sets in a cell. Although gametes have a haploid genome (n), most mammalian cells have diploid genomes (2n). The diploid status of most cells correlates with the number of probable alleles for each autosomal gene and makes it difficult to target these genes via mutagenesis techniques. Here, we describe a 7-week protocol for the derivation of mouse haploid embryonic stem cells (hESCs) from female gametes that also outlines how to maintain the cells once derived. We detail additional procedures that can be used with cell lines obtained from the mouse Haplobank, a biobank of >100,000 individual mouse hESC lines with targeted mutations in 16,970 genes. hESCs can spontaneously diploidize and can be maintained in both haploid and diploid states. Mouse hESCs are genomically and karyotypically stable, are innately immortal and isogenic, and can be derived in an array of differentiated cell types; they are thus highly amenable to genetic screens and to defining molecular connectivity pathways.
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http://dx.doi.org/10.1038/s41596-019-0169-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6997032PMC
July 2019

Establishment of porcine and human expanded potential stem cells.

Nat Cell Biol 2019 06 3;21(6):687-699. Epub 2019 Jun 3.

Key Laboratory of Regenerative Biology of Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China.

We recently derived mouse expanded potential stem cells (EPSCs) from individual blastomeres by inhibiting the critical molecular pathways that predispose their differentiation. EPSCs had enriched molecular signatures of blastomeres and possessed developmental potency for all embryonic and extra-embryonic cell lineages. Here, we report the derivation of porcine EPSCs, which express key pluripotency genes, are genetically stable, permit genome editing, differentiate to derivatives of the three germ layers in chimeras and produce primordial germ cell-like cells in vitro. Under similar conditions, human embryonic stem cells and induced pluripotent stem cells can be converted, or somatic cells directly reprogrammed, to EPSCs that display the molecular and functional attributes reminiscent of porcine EPSCs. Importantly, trophoblast stem-cell-like cells can be generated from both human and porcine EPSCs. Our pathway-inhibition paradigm thus opens an avenue for generating mammalian pluripotent stem cells, and EPSCs present a unique cellular platform for translational research in biotechnology and regenerative medicine.
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http://dx.doi.org/10.1038/s41556-019-0333-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7035105PMC
June 2019

Evolutionary and functional analysis of RBMY1 gene copy number variation on the human Y chromosome.

Hum Mol Genet 2019 08;28(16):2785-2798

Wellcome Genome Campus, Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, UK.

Human RBMY1 genes are located in four variable-sized clusters on the Y chromosome, expressed in male germ cells and possibly associated with sperm motility. We have re-investigated the mutational background and evolutionary history of the RBMY1 copy number distribution in worldwide samples and its relevance to sperm parameters in an Estonian cohort of idiopathic male factor infertility subjects. We estimated approximate RBMY1 copy numbers in 1218 1000 Genomes Project phase 3 males from sequencing read-depth, then chose 14 for valid ation by multicolour fibre-FISH. These fibre-FISH samples provided accurate calibration standards for the entire panel and led to detailed insights into population variation and mutational mechanisms. RBMY1 copy number worldwide ranged from 3 to 13 with a mode of 8. The two larger proximal clusters were the most variable, and additional duplications, deletions and inversions were detected. Placing the copy number estimates onto the published Y-SNP-based phylogeny of the same samples suggested a minimum of 562 mutational changes, translating to a mutation rate of 2.20 × 10-3 (95% CI 1.94 × 10-3 to 2.48 × 10-3) per father-to-son Y-transmission, higher than many short tandem repeat (Y-STRs), and showed no evidence for selection for increased or decreased copy number, but possible copy number stabilizing selection. An analysis of RBMY1 copy numbers among 376 infertility subjects failed to replicate a previously reported association with sperm motility and showed no significant effect on sperm count and concentration, serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone levels or testicular and semen volume. These results provide the first in-depth insights into the structural rearrangements underlying RBMY1 copy number variation across diverse human lineages.
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http://dx.doi.org/10.1093/hmg/ddz101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6687947PMC
August 2019

Functional linkage of gene fusions to cancer cell fitness assessed by pharmacological and CRISPR-Cas9 screening.

Nat Commun 2019 05 16;10(1):2198. Epub 2019 May 16.

Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, CB10 1SA, UK.

Many gene fusions are reported in tumours and for most their role remains unknown. As fusions are used for diagnostic and prognostic purposes, and are targets for treatment, it is crucial to assess their function in cancer. To systematically investigate the role of fusions in tumour cell fitness, we utilized RNA-sequencing data from 1011 human cancer cell lines to functionally link 8354 fusion events with genomic data, sensitivity to >350 anti-cancer drugs and CRISPR-Cas9 loss-of-fitness effects. Established clinically-relevant fusions were identified. Overall, detection of functional fusions was rare, including those involving cancer driver genes, suggesting that many fusions are dispensable for tumour fitness. Therapeutically actionable fusions involving RAF1, BRD4 and ROS1 were verified in new histologies. In addition, recurrent YAP1-MAML2 fusions were identified as activators of Hippo-pathway signaling in multiple cancer types. Our approach discriminates functional fusions, identifying new drivers of carcinogenesis and fusions that could have clinical implications.
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http://dx.doi.org/10.1038/s41467-019-09940-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522557PMC
May 2019

PiggyBac transposon tools for recessive screening identify B-cell lymphoma drivers in mice.

Nat Commun 2019 03 29;10(1):1415. Epub 2019 Mar 29.

The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK.

B-cell lymphoma (BCL) is the most common hematologic malignancy. While sequencing studies gave insights into BCL genetics, identification of non-mutated cancer genes remains challenging. Here, we describe PiggyBac transposon tools and mouse models for recessive screening and show their application to study clonal B-cell lymphomagenesis. In a genome-wide screen, we discover BCL genes related to diverse molecular processes, including signaling, transcriptional regulation, chromatin regulation, or RNA metabolism. Cross-species analyses show the efficiency of the screen to pinpoint human cancer drivers altered by non-genetic mechanisms, including clinically relevant genes dysregulated epigenetically, transcriptionally, or post-transcriptionally in human BCL. We also describe a CRISPR/Cas9-based in vivo platform for BCL functional genomics, and validate discovered genes, such as Rfx7, a transcription factor, and Phip, a chromatin regulator, which suppress lymphomagenesis in mice. Our study gives comprehensive insights into the molecular landscapes of BCL and underlines the power of genome-scale screening to inform biology.
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http://dx.doi.org/10.1038/s41467-019-09180-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6440946PMC
March 2019

Structural rearrangements generate cell-specific, gene-independent CRISPR-Cas9 loss of fitness effects.

Genome Biol 2019 02 5;20(1):27. Epub 2019 Feb 5.

Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.

Background: CRISPR-Cas9 genome editing is widely used to study gene function, from basic biology to biomedical research. Structural rearrangements are a ubiquitous feature of cancer cells and their impact on the functional consequences of CRISPR-Cas9 gene-editing has not yet been assessed.

Results: Utilizing CRISPR-Cas9 knockout screens for 250 cancer cell lines, we demonstrate that targeting structurally rearranged regions, in particular tandem or interspersed amplifications, is highly detrimental to cellular fitness in a gene-independent manner. In contrast, amplifications caused by whole chromosomal duplication have little to no impact on fitness. This effect is cell line specific and dependent on the ploidy status. We devise a copy-number ratio metric that substantially improves the detection of gene-independent cell fitness effects in CRISPR-Cas9 screens. Furthermore, we develop a computational tool, called Crispy, to account for these effects on a single sample basis and provide corrected gene fitness effects.

Conclusion: Our analysis demonstrates the importance of structural rearrangements in mediating the effect of CRISPR-Cas9-induced DNA damage, with implications for the use of CRISPR-Cas9 gene-editing in cancer cells.
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http://dx.doi.org/10.1186/s13059-019-1637-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362594PMC
February 2019

Human blood vessel organoids as a model of diabetic vasculopathy.

Nature 2019 01 16;565(7740):505-510. Epub 2019 Jan 16.

Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria.

The increasing prevalence of diabetes has resulted in a global epidemic. Diabetes is a major cause of blindness, kidney failure, heart attacks, stroke and amputation of lower limbs. These are often caused by changes in blood vessels, such as the expansion of the basement membrane and a loss of vascular cells. Diabetes also impairs the functions of endothelial cells and disturbs the communication between endothelial cells and pericytes. How dysfunction of endothelial cells and/or pericytes leads to diabetic vasculopathy remains largely unknown. Here we report the development of self-organizing three-dimensional human blood vessel organoids from pluripotent stem cells. These human blood vessel organoids contain endothelial cells and pericytes that self-assemble into capillary networks that are enveloped by a basement membrane. Human blood vessel organoids transplanted into mice form a stable, perfused vascular tree, including arteries, arterioles and venules. Exposure of blood vessel organoids to hyperglycaemia and inflammatory cytokines in vitro induces thickening of the vascular basement membrane. Human blood vessels, exposed in vivo to a diabetic milieu in mice, also mimic the microvascular changes found in patients with diabetes. DLL4 and NOTCH3 were identified as key drivers of diabetic vasculopathy in human blood vessels. Therefore, organoids derived from human stem cells faithfully recapitulate the structure and function of human blood vessels and are amenable systems for modelling and identifying the regulators of diabetic vasculopathy, a disease that affects hundreds of millions of patients worldwide.
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http://dx.doi.org/10.1038/s41586-018-0858-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116578PMC
January 2019

ATM orchestrates the DNA-damage response to counter toxic non-homologous end-joining at broken replication forks.

Nat Commun 2019 01 8;10(1):87. Epub 2019 Jan 8.

The Wellcome Trust and Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.

Mutations in the ATM tumor suppressor gene confer hypersensitivity to DNA-damaging chemotherapeutic agents. To explore genetic resistance mechanisms, we performed genome-wide CRISPR-Cas9 screens in cells treated with the DNA topoisomerase I inhibitor topotecan. Thus, we here establish that inactivating terminal components of the non-homologous end-joining (NHEJ) machinery or of the BRCA1-A complex specifically confer topotecan resistance to ATM-deficient cells. We show that hypersensitivity of ATM-mutant cells to topotecan or the poly-(ADP-ribose) polymerase (PARP) inhibitor olaparib reflects delayed engagement of homologous recombination at DNA-replication-fork associated single-ended double-strand breaks (DSBs), allowing some to be subject to toxic NHEJ. Preventing DSB ligation by NHEJ, or enhancing homologous recombination by BRCA1-A complex disruption, suppresses this toxicity, highlighting a crucial role for ATM in preventing toxic LIG4-mediated chromosome fusions. Notably, suppressor mutations in ATM-mutant backgrounds are different to those in BRCA1-mutant scenarios, suggesting new opportunities for patient stratification and additional therapeutic vulnerabilities for clinical exploitation.
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http://dx.doi.org/10.1038/s41467-018-07729-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6325118PMC
January 2019

The Malaria-Protective Human Glycophorin Structural Variant DUP4 Shows Somatic Mosaicism and Association with Hemoglobin Levels.

Am J Hum Genet 2018 11;103(5):769-776

Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK. Electronic address:

Glycophorin A and glycophorin B are red blood cell surface proteins and are both receptors for the parasite Plasmodium falciparum, which is the principal cause of malaria in sub-Saharan Africa. DUP4 is a complex structural genomic variant that carries extra copies of a glycophorin A-glycophorin B fusion gene and has a dramatic effect on malaria risk by reducing the risk of severe malaria by up to 40%. Using fiber-FISH and Illumina sequencing, we validate the structural arrangement of the glycophorin locus in the DUP4 variant and reveal somatic variation in copy number of the glycophorin B-glycophorin A fusion gene. By developing a simple, specific, PCR-based assay for DUP4, we show that the DUP4 variant reaches a frequency of 13% in the population of a malaria-endemic village in south-eastern Tanzania. We genotype a substantial proportion of that village and demonstrate an association of DUP4 genotype with hemoglobin levels, a phenotype related to malaria, using a family-based association test. Taken together, we show that DUP4 is a complex structural variant that may be susceptible to somatic variation and show that DUP4 is associated with a malarial-related phenotype in a longitudinally followed population.
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http://dx.doi.org/10.1016/j.ajhg.2018.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6218809PMC
November 2018

Chromosome assembly of large and complex genomes using multiple references.

Genome Res 2018 11 19;28(11):1720-1732. Epub 2018 Oct 19.

BioTuring Incorporated, San Diego, California 92121, USA.

Despite the rapid development of sequencing technologies, the assembly of mammalian-scale genomes into complete chromosomes remains one of the most challenging problems in bioinformatics. To help address this difficulty, we developed Ragout 2, a reference-assisted assembly tool that works for large and complex genomes. By taking one or more target assemblies (generated from an NGS assembler) and one or multiple related reference genomes, Ragout 2 infers the evolutionary relationships between the genomes and builds the final assemblies using a genome rearrangement approach. By using Ragout 2, we transformed NGS assemblies of 16 laboratory mouse strains into sets of complete chromosomes, leaving <5% of sequence unlocalized per set. Various benchmarks, including PCR testing and realigning of long Pacific Biosciences (PacBio) reads, suggest only a small number of structural errors in the final assemblies, comparable with direct assembly approaches. We applied Ragout 2 to the and genomes, which exhibit karyotype-scale variations compared with other genomes from the family. Chromosome painting maps confirmed most large-scale rearrangements that Ragout 2 detected. We applied Ragout 2 to improve draft sequences of three ape genomes that have recently been published. Ragout 2 transformed three sets of contigs (generated using PacBio reads only) into chromosome-scale assemblies with accuracy comparable to chromosome assemblies generated in the original study using BioNano maps, Hi-C, BAC clones, and FISH.
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http://dx.doi.org/10.1101/gr.236273.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6211643PMC
November 2018

Sixteen diverse laboratory mouse reference genomes define strain-specific haplotypes and novel functional loci.

Nat Genet 2018 11 1;50(11):1574-1583. Epub 2018 Oct 1.

Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.

We report full-length draft de novo genome assemblies for 16 widely used inbred mouse strains and find extensive strain-specific haplotype variation. We identify and characterize 2,567 regions on the current mouse reference genome exhibiting the greatest sequence diversity. These regions are enriched for genes involved in pathogen defence and immunity and exhibit enrichment of transposable elements and signatures of recent retrotransposition events. Combinations of alleles and genes unique to an individual strain are commonly observed at these loci, reflecting distinct strain phenotypes. We used these genomes to improve the mouse reference genome, resulting in the completion of 10 new gene structures. Also, 62 new coding loci were added to the reference genome annotation. These genomes identified a large, previously unannotated, gene (Efcab3-like) encoding 5,874 amino acids. Mutant Efcab3-like mice display anomalies in multiple brain regions, suggesting a possible role for this gene in the regulation of brain development.
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http://dx.doi.org/10.1038/s41588-018-0223-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6205630PMC
November 2018

Multicolor Fluorescence In Situ Hybridization (FISH) Approaches for Simultaneous Analysis of the Entire Human Genome.

Curr Protoc Hum Genet 2018 10 14;99(1):e70. Epub 2018 Sep 14.

Jackson Laboratory for Genomic Medicine, Farmington, Connecticut.

Analysis of the organization of the human genome is vital for understanding genetic diversity, human evolution, and disease pathogenesis. A number of approaches, such as multicolor fluorescence in situ hybridization (FISH) assays, cytogenomic microarray (CMA), and next-generation sequencing (NGS) technologies, are available for simultaneous analysis of the entire human genome. Multicolor FISH-based spectral karyotyping (SKY), multiplex FISH (M-FISH), and Rx-FISH may provide rapid identification of interchromosomal and intrachromosomal rearrangements as well as the origin of unidentified extrachromosomal elements. Recent advances in molecular cytogenetics have made it possible to efficiently examine the entire human genome in a single experiment at much higher resolution and specificity using CMA and NGS technologies. Here, we present an overview of the approaches available for genome-wide analyses. © 2018 by John Wiley & Sons, Inc.
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http://dx.doi.org/10.1002/cphg.70DOI Listing
October 2018

Chromosome painting in Glyphorynchus spirurus (Vieillot, 1819) detects a new fission in Passeriformes.

PLoS One 2018 23;13(8):e0202040. Epub 2018 Aug 23.

Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil.

Glyphorynchus spirurus (GSP), also called the Wedge-billed Woodcreeper (Furnariidae) has an extensive distribution in the Americas, including the Atlantic coast of Brazil. Nevertheless, there is no information about its karyotype or genome organization. To contribute to the knowledge of chromosomal evolution in Passeriformes we analysed the karyotype of Glyphorynchus spirurus by classic and molecular cytogenetics methods. We show that Glyphorynchus spirurus has a 2n = 80 karyotype with a fundamental number (FN) of 84, similar to the avian putative ancestral karyotype (PAK). Glyphorynchus spirurus pair 1 was heteromorphic in the Tapajós population whereby the short arms varied in sizes, possibly due to a pericentric inversion, as described in other Furnariidae birds. FISH with the Histone H5 probe revealed a signal in the pericentromeric region of G. spirurus chromosome 5 and rDNA 18S showed interstitial signal in GSP-1. Chromosome painting with Gallus gallus (GGA) macrochromosomes 1-9 probes showed disruption of chromosome syntenies of GGA-1, 2 and 4 by fission in Glyphorynchus spirurus. Our results confirm that the GGA1 centric fission is a synapomorphic character for the phylogenetic branch composed of Strigiformes, Passeriformes, Columbiformes and Falconiformes. On the other hand, the GGA-2 fission is reported here for the first time in Passeriformes. Chromosome painting with BOE whole chromosome probes confirmed these rearrangements in Glyphorynchus spirurus revealed by Gallus gallus 1-9 probes, in addition to enabling the establishment of genome-wide homology map.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0202040PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107148PMC
January 2019

Sequencing of Supernumerary Chromosomes of Red Fox and Raccoon Dog Confirms a Non-Random Gene Acquisition by B Chromosomes.

Genes (Basel) 2018 Aug 10;9(8). Epub 2018 Aug 10.

Institute of Molecular and Cellular Biology Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia.

B chromosomes (Bs) represent a variable addition to the main karyotype in some lineages of animals and plants. Bs accumulate through non-Mendelian inheritance and become widespread in populations. Despite the presence of multiple genes, most Bs lack specific phenotypic effects, although their influence on host genome epigenetic status and gene expression are recorded. Previously, using sequencing of isolated Bs of ruminants and rodents, we demonstrated that Bs originate as segmental duplications of specific genomic regions, and subsequently experience pseudogenization and repeat accumulation. Here, we used a similar approach to characterize Bs of the red fox ( L.) and the Chinese raccoon dog ( Gray). We confirm the previous findings of the gene on Bs of both species, but demostrate an independent origin of Bs in these species, with two reused regions. Comparison of gene ensembles in Bs of canids, ruminants, and rodents once again indicates enrichment with cell-cycle genes, development-related genes, and genes functioning in the neuron synapse. The presence of B-chromosomal copies of genes involved in cell-cycle regulation and tissue differentiation may indicate importance of these genes for B chromosome establishment.
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http://dx.doi.org/10.3390/genes9080405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116037PMC
August 2018

Shieldin complex promotes DNA end-joining and counters homologous recombination in BRCA1-null cells.

Nat Cell Biol 2018 08 18;20(8):954-965. Epub 2018 Jul 18.

The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, UK.

BRCA1 deficiencies cause breast, ovarian, prostate and other cancers, and render tumours hypersensitive to poly(ADP-ribose) polymerase (PARP) inhibitors. To understand the resistance mechanisms, we conducted whole-genome CRISPR-Cas9 synthetic-viability/resistance screens in BRCA1-deficient breast cancer cells treated with PARP inhibitors. We identified two previously uncharacterized proteins, C20orf196 and FAM35A, whose inactivation confers strong PARP-inhibitor resistance. Mechanistically, we show that C20orf196 and FAM35A form a complex, 'Shieldin' (SHLD1/2), with FAM35A interacting with single-stranded DNA through its C-terminal oligonucleotide/oligosaccharide-binding fold region. We establish that Shieldin acts as the downstream effector of 53BP1/RIF1/MAD2L2 to promote DNA double-strand break (DSB) end-joining by restricting DSB resection and to counteract homologous recombination by antagonizing BRCA2/RAD51 loading in BRCA1-deficient cells. Notably, Shieldin inactivation further sensitizes BRCA1-deficient cells to cisplatin, suggesting how defining the SHLD1/2 status of BRCA1-deficient tumours might aid patient stratification and yield new treatment opportunities. Highlighting this potential, we document reduced SHLD1/2 expression in human breast cancers displaying intrinsic or acquired PARP-inhibitor resistance.
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http://dx.doi.org/10.1038/s41556-018-0140-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145444PMC
August 2018

Chromosomal evolution and phylogeny in the Nullicauda group (Chiroptera, Phyllostomidae): evidence from multidirectional chromosome painting.

BMC Evol Biol 2018 04 25;18(1):62. Epub 2018 Apr 25.

Laboratório de Citogenética, CEABIO, ICB, Universidade Federal do Pará, Av. Bernardo Sayão, sn. Guamá, Belém, Pará, 66075-900, Brazil.

Background: The family Phyllostomidae (Chiroptera) shows wide morphological, molecular and cytogenetic variation; many disagreements regarding its phylogeny and taxonomy remains to be resolved. In this study, we use chromosome painting with whole chromosome probes from the Phyllostomidae Phyllostomus hastatus and Carollia brevicauda to determine the rearrangements among several genera of the Nullicauda group (subfamilies Gliphonycterinae, Carolliinae, Rhinophyllinae and Stenodermatinae).

Results: These data, when compared with previously published chromosome homology maps, allow the construction of a phylogeny comparable to those previously obtained by morphological and molecular analysis. Our phylogeny is largely in agreement with that proposed with molecular data, both on relationships between the subfamilies and among genera; it confirms, for instance, that Carollia and Rhinophylla, previously considered as part of the same subfamily are, in fact, distant genera.

Conclusions: The occurrence of the karyotype considered ancestral for this family in several different branches suggests that the diversification of Phyllostomidae into many subfamilies has occurred in a short period of time. Finally, the comparison with published maps using human whole chromosome probes allows us to track some syntenic associations prior to the emergence of this family.
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http://dx.doi.org/10.1186/s12862-018-1176-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5921544PMC
April 2018