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2. |
- Jarvis, Erich D., et al.
(author)
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Whole-genome analyses resolve early branches in the tree of life of modern birds
- 2014
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 346:6215, s. 1320-1331
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Journal article (peer-reviewed)abstract
- To better determine the history of modern birds, we performed a genome-scale phylogenetic analysis of 48 species representing all orders of Neoaves using phylogenomic methods created to handle genome-scale data. We recovered a highly resolved tree that confirms previously controversial sister or close relationships. We identified the first divergence in Neoaves, two groups we named Passerea and Columbea, representing independent lineages of diverse and convergently evolved land and water bird species. Among Passerea, we infer the common ancestor of core landbirds to have been an apex predator and confirm independent gains of vocal learning. Among Columbea, we identify pigeons and flamingoes as belonging to sister clades. Even with whole genomes, some of the earliest branches in Neoaves proved challenging to resolve, which was best explained by massive protein-coding sequence convergence and high levels of incomplete lineage sorting that occurred during a rapid radiation after the Cretaceous-Paleogene mass extinction event about 66 million years ago.
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3. |
- Sinjela, Kwangaika Mwala, et al.
(author)
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Exploring for-profit healthcare providers’ perceptions of inclusion in the Zambia National Health Insurance Scheme : A qualitative content analysis
- 2022
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:5 May
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Journal article (peer-reviewed)abstract
- Background In 2019, Zambia introduced the national health insurance (NHI) as a healthcare financing strategy to increase universal access to health care services. The private health sector can complement public sector providers as service providers under the NHI. As such, the NHI Management Authority seeks to accredit for-profit private healthcare facilities in the NHI. Ascertaining factors that influence private-for-profit health providers to participate in the NHI is essential, but the evidence is lacking. In this study, we aimed to explore and characterize perceptions and experiences of for-profit private hospitals, dental clinics, eye clinics, diagnostic centres, and pharmacies regarding their inclusion in the NHI. Methods We conducted in-depth interviews with owners or management officers of purposively sampled private health care providers in Lusaka, Zambia (n = 22) between May and June 2020. Qualitative content analysis was used to analyse data. Results The findings highlight low awareness of the NHI among providers and a need to understand the NHI. Providers revealed their positions and views on the accreditation process and payment arrangements and stated that their participation would complement the NHI. They also cited conditions to participate in the NHI, highlighted opportunities and challenges of engaging in the NHI, and expressed a need for sustainable ways of governing the scheme. Conclusion The assessment of health providers’ inclusion in the NHI scheme is multifaceted. The results of this study surfaced factors such as raising awareness on the NHI among providers and how their concerns on aspects such as payments can be considered as inputs to enlighten consensual agreements between the NHI authority and health providers in leveraging the private health sector. Private providers’ concerns must be further understood and considered as the NHI strives to include this group as health care providers in the scheme.
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4. |
- Zhang, Guojie, et al.
(author)
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Comparative genomics reveals insights into avian genome evolution and adaptation
- 2014
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 346:6215, s. 1311-1320
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Journal article (peer-reviewed)abstract
- Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits.
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5. |
- Balakrishnan, Christopher N., et al.
(author)
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Gene duplication and fragmentation in the zebra finch major histocompatibility complex
- 2010
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In: BMC Biology. - : Springer Science and Business Media LLC. - 1741-7007. ; 8, s. 29-
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Journal article (peer-reviewed)abstract
- Background: Due to its high polymorphism and importance for disease resistance, the major histocompatibility complex (MHC) has been an important focus of many vertebrate genome projects. Avian MHC organization is of particular interest because the chicken Gallus gallus, the avian species with the best characterized MHC, possesses a highly streamlined minimal essential MHC, which is linked to resistance against specific pathogens. It remains unclear the extent to which this organization describes the situation in other birds and whether it represents a derived or ancestral condition. The sequencing of the zebra finch Taeniopygia guttata genome, in combination with targeted bacterial artificial chromosome (BAC) sequencing, has allowed us to characterize an MHC from a highly divergent and diverse avian lineage, the passerines. Results: The zebra finch MHC exhibits a complex structure and history involving gene duplication and fragmentation. The zebra finch MHC includes multiple Class I and Class II genes, some of which appear to be pseudogenes, and spans a much more extensive genomic region than the chicken MHC, as evidenced by the presence of MHC genes on each of seven BACs spanning 739 kb. Cytogenetic (FISH) evidence and the genome assembly itself place core MHC genes on as many as four chromosomes with TAP and Class I genes mapping to different chromosomes. MHC Class II regions are further characterized by high endogenous retroviral content. Lastly, we find strong evidence of selection acting on sites within passerine MHC Class I and Class II genes. Conclusion: The zebra finch MHC differs markedly from that of the chicken, the only other bird species with a complete genome sequence. The apparent lack of synteny between TAP and the expressed MHC Class I locus is in fact reminiscent of a pattern seen in some mammalian lineages and may represent convergent evolution. Our analyses of the zebra finch MHC suggest a complex history involving chromosomal fission, gene duplication and translocation in the history of the MHC in birds, and highlight striking differences in MHC structure and organization among avian lineages.
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- Franchini, Paolo, et al.
(author)
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Long-term experimental hybridisation results in the evolution of a new sex chromosome in swordtail fish
- 2018
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In: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- The remarkable diversity of sex determination mechanisms known in fish may be fuelled by exceptionally high rates of sex chromosome turnovers or transitions. However, the evolutionary causes and genomic mechanisms underlying this variation and instability are yet to be understood. Here we report on an over 30-year evolutionary experiment in which we tested the genomic consequences of hybridisation and selection between two Xiphophorus fish species with different sex chromosome systems. We find that introgression and imposing selection for pigmentation phenotypes results in the retention of an unexpectedly large maternally derived genomic region. During the hybridisation process, the sex-determining region of the X chromosome from one parental species was translocated to an autosome in the hybrids leading to the evolution of a new sex chromosome. Our results highlight the complexity of factors contributing to patterns observed in hybrid genomes, and we experimentally demonstrate that hybridisation can catalyze rapid evolution of a new sex chromosome.
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8. |
- Hillier, Ladeana W, et al.
(author)
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
- 2004
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In: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
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Journal article (peer-reviewed)abstract
- We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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9. |
- Hoencamp, Claire, et al.
(author)
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3D genomics across the tree of life reveals condensin II as a determinant of architecture type
- 2021
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 372:6545, s. 984-989
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Journal article (peer-reviewed)abstract
- We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional (3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedly during eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with the absence of condensin II subunits. Moreover, condensin II depletion converts the architecture of the human genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state, centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physical model in which lengthwise compaction of chromosomes by condensin II during mitosis determines chromosome-scale genome architecture, with effects that are retained during the subsequent interphase. This mechanism likely has been conserved since the last common ancestor of all eukaryotes.
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10. |
- Holt, Carson, et al.
(author)
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Improved Genome Assembly and Annotation for the Rock Pigeon (Columba livia)
- 2018
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In: G3. - : GENETICS SOCIETY AMERICA. - 2160-1836. ; 8:5, s. 1391-1398
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Journal article (peer-reviewed)abstract
- The domestic rock pigeon (Columba livia) is among the most widely distributed and phenotypically diverse avian species. C. livia is broadly studied in ecology, genetics, physiology, behavior, and evolutionary biology, and has recently emerged as a model for understanding the molecular basis of anatomical diversity, the magnetic sense, and other key aspects of avian biology. Here we report an update to the C. livia genome reference assembly and gene annotation dataset. Greatly increased scaffold lengths in the updated reference assembly, along with an updated annotation set, provide improved tools for evolutionary and functional genetic studies of the pigeon, and for comparative avian genomics in general.
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11. |
- Kuderna, Lukas F. K., et al.
(author)
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A 3-way hybrid approach to generate a new high-quality chimpanzee reference genome (Pan_tro_3.0)
- 2017
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In: GigaScience. - : Oxford University Press (OUP). - 2047-217X. ; 6:11, s. 1-6
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Journal article (peer-reviewed)abstract
- The chimpanzee is arguably the most important species for the study of human origins. A key resource for these studies is a high-quality reference genome assembly; however, as with most mammalian genomes, the current iteration of the chimpanzee reference genome assembly is highly fragmented. In the current iteration of the chimpanzee reference genome assembly (Pan tro 2.1.4), the sequence is scattered across more then 183 000 contigs, incorporating more than 159 000 gaps, with a genome-wide contig N50 of 51 Kbp. In this work, we produce an extensive and diverse array of sequencing datasets to rapidly assemble a new chimpanzee reference that surpasses previous iterations in bases represented and organized in large scaffolds. To this end, we show substantial improvements over the current release of the chimpanzee genome (Pan tro 2.1.4) by several metrics, such as increased contiguity by > 750% and 300% on contigs and scaffolds, respectively, and closure of 77% of gaps in the Pan tro 2.1.4 assembly gaps spanning > 850 Kbp of the novel coding sequence based on RNASeq data. We further report more than 2700 genes that had putatively erroneous frame-shift predictions to human in Pan tro 2.1.4 and show a substantial increase in the annotation of repetitive elements. We apply a simple 3-way hybrid approach to considerably improve the reference genome assembly for the chimpanzee, providing a valuable resource for the study of human origins. Furthermore, we produce extensive sequencing datasets that are all derived from the same cell line, generating a broad non-human benchmark dataset.
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12. |
- Künstner, Axel, et al.
(author)
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Comparative genomics based on massive parallel transcriptome sequencing reveals patterns of substitution and selection across 10 bird species
- 2010
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In: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 19:Suppl.1, s. 266-276
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Journal article (peer-reviewed)abstract
- Next-generation sequencing technology provides an attractive means to obtain largescale sequence data necessary for comparative genomic analysis. To analyse the patterns of mutation rate variation and selection intensity across the avian genome, we performed brain transcriptome sequencing using Roche 454 technology of 10 different non-model avian species. Contigs from de novo assemblies were aligned to the two available avian reference genomes, chicken and zebra finch. In total, we identified 6499 different genes across all 10 species, with ∼1000 genes found in each full run per species. We found evidence for a higher mutation rate of the Z chromosome than of autosomes (male-biased mutation) and a negative correlation between the neutral substitution rate (dS) and chromosome size. Analyses of the mean dN/dS ratio (ω) of genes across chromosomes supported the Hill-Robertson effect (the effect of selection at linked loci) and point at stochastic problems with x as an independent measure of selection. Overall, this study demonstrates the usefulness of next-generation sequencing for obtaining genomic resources for comparative genomic analysis of non-model organisms.
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13. |
- Lindblad-Toh, Kerstin, et al.
(author)
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A high-resolution map of human evolutionary constraint using 29 mammals
- 2011
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 478:7370, s. 476-482
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Journal article (peer-reviewed)abstract
- The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering similar to 4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for similar to 60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate-and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease.
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14. |
- Malbet, F., et al.
(author)
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Faint objects in motion: the new frontier of high precision astrometry
- 2021
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In: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 51:3, s. 845-886
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Journal article (peer-reviewed)abstract
- Sky survey telescopes and powerful targeted telescopes play complementary roles in astronomy. In order to investigate the nature and characteristics of the motions of very faint objects, a flexibly-pointed instrument capable of high astrometric accuracy is an ideal complement to current astrometric surveys and a unique tool for precision astrophysics. Such a space-based mission will push the frontier of precision astrometry from evidence of Earth-mass habitable worlds around the nearest stars, to distant Milky Way objects, and out to the Local Group of galaxies. As we enter the era of the James Webb Space Telescope and the new ground-based, adaptive-optics-enabled giant telescopes, by obtaining these high precision measurements on key objects that Gaia could not reach, a mission that focuses on high precision astrometry science can consolidate our theoretical understanding of the local Universe, enable extrapolation of physical processes to remote redshifts, and derive a much more consistent picture of cosmological evolution and the likely fate of our cosmos. Already several missions have been proposed to address the science case of faint objects in motion using high precision astrometry missions: NEAT proposed for the ESA M3 opportunity, micro-NEAT for the S1 opportunity, and Theia for the M4 and M5 opportunities. Additional new mission configurations adapted with technological innovations could be envisioned to pursue accurate measurements of these extremely small motions. The goal of this White Paper is to address the fundamental science questions that are at stake when we focus on the motions of faint sky objects and to briefly review instrumentation and mission profiles.
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15. |
- Schartl, Manfred, et al.
(author)
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The Developmental and Genetic Architecture of the Sexually Selected Male Ornament of Swordtails
- 2021
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In: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 31:5, s. 911-922.e4
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Journal article (peer-reviewed)abstract
- Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin-the ``sword''-in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome and are located in the genomic region associated with this trait we identify the potassium channel, Kcnh8, as a sword development gene. In addition to its neural function kcnh8 performs a known role in fin growth. These findings indicate that during evolution of swordtails a brain gene has been co-opted for an additional novel function in establishing a male ornament.
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17. |
- Warren, Wesley C, et al.
(author)
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The genome of a songbird
- 2010
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 464:7289, s. 757-762
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Journal article (peer-reviewed)abstract
- The zebra finch is an important model organism in several fields with unique relevance to human neuroscience. Like other songbirds, the zebra finch communicates through learned vocalizations, an ability otherwise documented only in humans and a few other animals and lacking in the chicken-the only bird with a sequenced genome until now. Here we present a structural, functional and comparative analysis of the genome sequence of the zebra finch (Taeniopygia guttata), which is a songbird belonging to the large avian order Passeriformes. We find that the overall structures of the genomes are similar in zebra finch and chicken, but they differ in many intrachromosomal rearrangements, lineage-specific gene family expansions, the number of long-terminal-repeat-based retrotransposons, and mechanisms of sex chromosome dosage compensation. We show that song behaviour engages gene regulatory networks in the zebra finch brain, altering the expression of long non-coding RNAs, microRNAs, transcription factors and their targets. We also show evidence for rapid molecular evolution in the songbird lineage of genes that are regulated during song experience. These results indicate an active involvement of the genome in neural processes underlying vocal communication and identify potential genetic substrates for the evolution and regulation of this behaviour.
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19. |
- Zody, Michael C., et al.
(author)
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Evolutionary toggling of the MAPT 17q21.31 inversion region
- 2008
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 40:9, s. 1076-83
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Journal article (peer-reviewed)abstract
- Using comparative sequencing approaches, we investigated the evolutionary history of the European-enriched 17q21.31 MAPT inversion polymorphism. We present a detailed, BAC-based sequence assembly of the inverted human H2 haplotype and compare it to the sequence structure and genetic variation of the corresponding 1.5-Mb region for the noninverted H1 human haplotype and that of chimpanzee and orangutan. We found that inversion of the MAPT region is similarly polymorphic in other great ape species, and we present evidence that the inversions occurred independently in chimpanzees and humans. In humans, the inversion breakpoints correspond to core duplications with the LRRC37 gene family. Our analysis favors the H2 configuration and sequence haplotype as the likely great ape and human ancestral state, with inversion recurrences during primate evolution. We show that the H2 architecture has evolved more extensive sequence homology, perhaps explaining its tendency to undergo microdeletion associated with mental retardation in European populations.
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