scholarly journals Traveler, a New DD35E Family of Tc1/Mariner Transposons, Invaded Vertebrates Very Recently

2020 ◽  
Vol 12 (3) ◽  
pp. 66-76 ◽  
Author(s):  
Wencheng Zong ◽  
Bo Gao ◽  
Mohamed Diaby ◽  
Dan Shen ◽  
Saisai Wang ◽  
...  

Abstract The discovery of new members of the Tc1/mariner superfamily of transposons is expected based on the increasing availability of genome sequencing data. Here, we identified a new DD35E family termed Traveler (TR). Phylogenetic analyses of its DDE domain and full-length transposase showed that, although TR formed a monophyletic clade, it exhibited the highest sequence identity and closest phylogenetic relationship with DD34E/Tc1. This family displayed a very restricted taxonomic distribution in the animal kingdom and was only detected in ray-finned fish, anura, and squamata, including 91 vertebrate species. The structural organization of TRs was highly conserved across different classes of animals. Most intact TR transposons had a length of ∼1.5 kb (range 1,072–2,191 bp) and harbored a single open reading frame encoding a transposase of ∼340 aa (range 304–350 aa) flanked by two short-terminal inverted repeats (13–68 bp). Several conserved motifs, including two helix-turn-helix motifs, a GRPR motif, a nuclear localization sequence, and a DDE domain, were also identified in TR transposases. This study also demonstrated the presence of horizontal transfer events of TRs in vertebrates, whereas the average sequence identities and the evolutionary dynamics of TR elements across species and clusters strongly indicated that the TR family invaded the vertebrate lineage very recently and that some of these elements may be currently active, combining the intact TR copies in multiple lineages of vertebrates. These data will contribute to the understanding of the evolutionary history of Tc1/mariner transposons and that of their hosts.

2017 ◽  
Author(s):  
Ryan M. Moore ◽  
Amelia O. Harrison ◽  
Sean M. McAllister ◽  
Shawn W. Polson ◽  
K. Eric Wommack

ABSTRACTPhylogenetic trees are an important analytical tool for evaluating community diversity and evolutionary history. In the case of microorganisms, the decreasing cost of sequencing has enabled researchers to generate ever-larger sequence datasets, which in turn have begun to fill gaps in the evolutionary history of microbial groups. However, phylogenetic analyses of these types of datasets create complex trees that can be challenging to interpret. Scientific inferences made by visual inspection of phylogenetic trees can be simplified and enhanced by customizing various parts of the tree. Yet, manual customization is time-consuming and error prone, and programs designed to assist in batch tree customization often require programming experience or complicated file formats for annotation. Iroki, a user-friendly web interface for tree visualization, addresses these issues by providing automatic customization of large trees based on metadata contained in tab-separated text files. Iroki’s utility for exploring biological and ecological trends in sequencing data was demonstrated through a variety of microbial ecology applications in which trees with hundreds to thousands of leaf nodes were customized according to extensive collections of metadata. The Iroki web application and documentation are available at https://www.iroki.net or through the VIROME portal (http://virome.dbi.udel.edu). Iroki’s source code is released under the MIT license and is available at https://github.com/mooreryan/iroki.


2019 ◽  
Vol 116 (6) ◽  
pp. 2146-2151 ◽  
Author(s):  
Tetsuto Miyashita ◽  
Michael I. Coates ◽  
Robert Farrar ◽  
Peter Larson ◽  
Phillip L. Manning ◽  
...  

Hagfish depart so much from other fishes anatomically that they were sometimes considered not fully vertebrate. They may represent: (i) an anatomically primitive outgroup of vertebrates (the morphology-based craniate hypothesis); or (ii) an anatomically degenerate vertebrate lineage sister to lampreys (the molecular-based cyclostome hypothesis). This systematic conundrum has become a prominent case of conflict between morphology- and molecular-based phylogenies. To date, the fossil record has offered few insights to this long-branch problem or the evolutionary history of hagfish in general, because unequivocal fossil members of the group are unknown. Here, we report an unequivocal fossil hagfish from the early Late Cretaceous of Lebanon. The soft tissue anatomy includes key attributes of living hagfish: cartilages of barbels, postcranial position of branchial apparatus, and chemical traces of slime glands. This indicates that the suite of characters unique to living hagfish appeared well before Cretaceous times. This new hagfish prompted a reevaluation of morphological characters for interrelationships among jawless vertebrates. By addressing nonindependence of characters, our phylogenetic analyses recovered hagfish and lampreys in a clade of cyclostomes (congruent with the cyclostome hypothesis) using only morphological data. This new phylogeny places the fossil taxon within the hagfish crown group, and resolved other putative fossil cyclostomes to the stem of either hagfish or lamprey crown groups. These results potentially resolve the morphological–molecular conflict at the base of the Vertebrata. Thus, assessment of character nonindependence may help reconcile morphological and molecular inferences for other major discords in animal phylogeny.


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8584 ◽  
Author(s):  
Ryan M. Moore ◽  
Amelia O. Harrison ◽  
Sean M. McAllister ◽  
Shawn W. Polson ◽  
K. Eric Wommack

Phylogenetic trees are an important analytical tool for evaluating community diversity and evolutionary history. In the case of microorganisms, the decreasing cost of sequencing has enabled researchers to generate ever-larger sequence datasets, which in turn have begun to fill gaps in the evolutionary history of microbial groups. However, phylogenetic analyses of these types of datasets create complex trees that can be challenging to interpret. Scientific inferences made by visual inspection of phylogenetic trees can be simplified and enhanced by customizing various parts of the tree. Yet, manual customization is time-consuming and error prone, and programs designed to assist in batch tree customization often require programming experience or complicated file formats for annotation. Iroki, a user-friendly web interface for tree visualization, addresses these issues by providing automatic customization of large trees based on metadata contained in tab-separated text files. Iroki’s utility for exploring biological and ecological trends in sequencing data was demonstrated through a variety of microbial ecology applications in which trees with hundreds to thousands of leaf nodes were customized according to extensive collections of metadata. The Iroki web application and documentation are available at https://www.iroki.net or through the VIROME portal http://virome.dbi.udel.edu. Iroki’s source code is released under the MIT license and is available at https://github.com/mooreryan/iroki.


Author(s):  
Sergio A Muñoz-Gómez ◽  
Keira Durnin ◽  
Laura Eme ◽  
Christopher Paight ◽  
Christopher E Lane ◽  
...  

Abstract A most interesting exception within the parasitic Apicomplexa is Nephromyces, an extracellular, probably mutualistic, endosymbiont found living inside molgulid ascidian tunicates (i.e., sea squirts). Even though Nephromyces is now known to be an apicomplexan, many other questions about its nature remain unanswered. To gain further insights into the biology and evolutionary history of this unusual apicomplexan, we aimed to (1) find the precise phylogenetic position of Nephromyces within the Apicomplexa, (2) search for the apicoplast genome of Nephromyces, and (3) infer the major metabolic pathways in the apicoplast of Nephromyces. To do this, we sequenced a metagenome and a metatranscriptome from the molgulid renal sac, the specialized habitat where Nephromyces thrives. Our phylogenetic analyses of conserved nucleus-encoded genes robustly suggest that Nephromyces is a novel lineage sister to the Hematozoa, which comprises both the Haemosporidia (e.g., Plasmodium) and the Piroplasmida (e.g., Babesia and Theileria). Furthermore, a survey of the renal sac metagenome revealed 13 small contigs that closely resemble the genomes of the non-photosynthetic reduced plastids, or apicoplasts, of other apicomplexans. We show that these apicoplast genomes correspond to a diverse set of most closely related but genetically divergent Nephromyces lineages that co-inhabit a single tunicate host. In addition, the apicoplast of Nephromyces appears to have retained all biosynthetic pathways inferred to have been ancestral to parasitic apicomplexans. Our results shed light on the evolutionary history of the only probably mutualistic apicomplexan known, Nephromyces, and provide context for a better understanding of its life style and intricate symbiosis.


2021 ◽  
Author(s):  
Caitlin Cherryh ◽  
Bui Quang Minh ◽  
Rob Lanfear

AbstractMost phylogenetic analyses assume that the evolutionary history of an alignment (either that of a single locus, or of multiple concatenated loci) can be described by a single bifurcating tree, the so-called the treelikeness assumption. Treelikeness can be violated by biological events such as recombination, introgression, or incomplete lineage sorting, and by systematic errors in phylogenetic analyses. The incorrect assumption of treelikeness may then mislead phylogenetic inferences. To quantify and test for treelikeness in alignments, we develop a test statistic which we call the tree proportion. This statistic quantifies the proportion of the edge weights in a phylogenetic network that are represented in a bifurcating phylogenetic tree of the same alignment. We extend this statistic to a statistical test of treelikeness using a parametric bootstrap. We use extensive simulations to compare tree proportion to a range of related approaches. We show that tree proportion successfully identifies non-treelikeness in a wide range of simulation scenarios, and discuss its strengths and weaknesses compared to other approaches. The power of the tree-proportion test to reject non-treelike alignments can be lower than some other approaches, but these approaches tend to be limited in their scope and/or the ease with which they can be interpreted. Our recommendation is to test treelikeness of sequence alignments with both tree proportion and mosaic methods such as 3Seq. The scripts necessary to replicate this study are available at https://github.com/caitlinch/treelikeness


Author(s):  
Olga Kozhar ◽  
Mee-Sook Kim ◽  
Jorge Ibarra Caballero ◽  
Ned Klopfenstein ◽  
Phil Cannon ◽  
...  

Emerging pathogens have been increasing exponentially over the last century. The knowledge on whether these organisms are native to ecosystems or have been recently introduced is often of great importance. Understanding the ecological and evolutionary processes promoting emergence can help to control their spread and forecast epidemics. Using restriction site-associated DNA sequencing data, we studied genetic relationships, pathways of spread, and evolutionary history of Phellinus noxius, an emerging root-rotting fungus of unknown origin, in eastern Asia, Australia, and the Pacific Islands. We analyzed patterns of genetic variation using Bayesian inference, maximum likelihood phylogeny, populations splits and mixtures measuring correlations in allele frequencies and genetic drift, and finally applied coalescent based theory using approximate Bayesian computation (ABC) with supervised machine learning. Population structure analyses revealed five genetic groups with signatures of complex recent and ancient migration histories. The most probable scenario of ancient pathogen spread is movement from west to east: from Malaysia to the Pacific Islands, with subsequent spread to Taiwan and Australia. Furthermore, ABC analyses indicate that P. noxius spread occurred thousands of generations ago, contradicting previous assumptions that it was recently introduced in multiple areas. Our results suggest that recent emergence of P. noxius in east Asia, Australia, and the Pacific Islands is likely driven by anthropogenic and natural disturbances, including deforestation, land-use change, severe weather events, and introduction of exotic plants. This study provides a novel example of utilization of genome wide allele frequency data to unravel dynamics of pathogen emergence under conditions of changing ecosystems.


2021 ◽  
Author(s):  
Keerthic Aswin ◽  
Srinivasan Ramachandran ◽  
Vivek T Natarajan

AbstractEvolutionary history of coronaviruses holds the key to understand mutational behavior and prepare for possible future outbreaks. By performing comparative genome analysis of nidovirales that contain the family of coronaviruses, we traced the origin of proofreading, surprisingly to the eukaryotic antiviral component ZNFX1. This common recent ancestor contributes two zinc finger (ZnF) motifs that are unique to viral exonuclease, segregating them from DNA proof-readers. Phylogenetic analyses indicate that following acquisition, genomes of coronaviruses retained and further fine-tuned proofreading exonuclease, whereas related families harbor substitution of key residues in ZnF1 motif concomitant to a reduction in their genome sizes. Structural modelling followed by simulation suggests the role of ZnF in RNA binding. Key ZnF residues strongly coevolve with replicase, and the helicase involved in duplex RNA unwinding. Hence, fidelity of replication in coronaviruses is a result of convergent evolution, that enables maintenance of genome stability akin to cellular proofreading systems.


2019 ◽  
Vol 286 (1897) ◽  
pp. 20182929 ◽  
Author(s):  
Elena A. Ritschard ◽  
Robert R. Fitak ◽  
Oleg Simakov ◽  
Sönke Johnsen

Coleoid cephalopods show unique morphological and neural novelties, such as arms with tactile and chemosensory suckers and a large complex nervous system. The evolution of such cephalopod novelties has been attributed at a genomic level to independent gene family expansions, yet the exact association and the evolutionary timing remain unclear. In the octopus genome, one such expansion occurred in the G-protein-coupled receptors (GPCRs) repertoire, a superfamily of proteins that mediate signal transduction. Here, we assessed the evolutionary history of this expansion and its relationship with cephalopod novelties. Using phylogenetic analyses, at least two cephalopod- and two octopus-specific GPCR expansions were identified. Signatures of positive selection were analysed within the four groups, and the locations of these sequences in the Octopus bimaculoides genome were inspected. Additionally, the expression profiles of cephalopod GPCRs across various tissues were extracted from available transcriptomic data. Our results reveal the evolutionary history of cephalopod GPCRs. Unexpanded cephalopod GPCRs shared with other bilaterians were found to be mainly nervous tissue specific. By contrast, duplications that are shared between octopus and the bobtail squid or specific to the octopus' lineage generated copies with divergent expression patterns devoted to tissues outside of the brain. The acquisition of novel expression domains was accompanied by gene order rearrangement through either translocation or duplication and gene loss. Lastly, expansions showed signs of positive selection and some were found to form tandem clusters with shared conserved expression profiles in cephalopod innovations such as the axial nerve cord. Altogether, our results contribute to the understanding of the molecular and evolutionary history of signal transduction and provide insights into the role of this expansion during the emergence of cephalopod novelties and/or adaptations.


2002 ◽  
Vol 93 (4) ◽  
pp. 333-353 ◽  
Author(s):  
Julia J. Day

ABSTRACTThe Eocene sparid fauna (Teleostei: Percoidei) from Monte Bolca, Italy and from the London Clay, U.K. is revised based on re-examination of the type material and phylogenetic analyses of primarily osteological data. Two phylogenetic analyses, one of the Eocene taxa and a combined analysis of fossil and extant taxa, were performed. The addition of fossils to the extant data greatly increased numbers of most parsimonious trees, destabilising and obscuring basal relationships within the Sparidae. Combination of the data from fossil and extant data also affected relationships among the fossil taxa, changing some from those recovered using fossil data alone and destabilising others. Successive approximations character weighting supported the inclusion of the Eocene taxa within a monophyletic Sparidae. The genus Sparnodus, as previously conceived, is paraphyletic and is partitioned to remove the paraphyly. Five monotypic genera are recognised, including three new genera, Abromasta, Ellaserrata and Pseudosparnodus. Inclusion of the fossils in the phylogenetic analysis implies a minimum age of origin for the Sparidae of 55 Ma with most Recent sparid fauna in place no later than the Miocene, and provides further evidence that the diversification of feeding strategies occurred early on in the evolutionary history of the group.


PLoS ONE ◽  
2017 ◽  
Vol 12 (10) ◽  
pp. e0186085 ◽  
Author(s):  
Amy B. Baird ◽  
Janet K. Braun ◽  
Mark D. Engstrom ◽  
Ashlyn C. Holbert ◽  
Maritza G. Huerta ◽  
...  

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