The diversity and evolution of chelicerate hemocyanins

<p>Abstract</p> <p>Background</p> <p>Oxygen transport in the hemolymph of many arthropod species is facilitated by large copper-proteins referred to as hemocyanins. Arthropod hemocyanins are hexamers or oligomers of hexamers, which are characterized by a high O₂transport capacity and a high cooperativity, thereby enhancing O₂supply. Hemocyanin subunit sequences had been available from horseshoe crabs (Xiphosura) and various spiders (Araneae), but not from any other chelicerate taxon. To trace the evolution of hemocyanins and the emergence of the large hemocyanin oligomers, hemocyanin cDNA sequences were obtained from representatives of selected chelicerate classes.</p> <p>Results</p> <p>Hemocyanin subunits from a sea spider, a scorpion, a whip scorpion and a whip spider were sequenced. Hemocyanin has been lost in Opiliones, Pseudoscorpiones, Solifugae and Acari, which may be explained by the evolution of trachea (i.e., taxon Apulmonata). Bayesian phylogenetic analysis was used to reconstruct the evolution of hemocyanin subunits and a relaxed molecular clock approach was applied to date the major events. While the sea spider has a simple hexameric hemocyanin, four distinct subunit types evolved before Xiphosura and Arachnida diverged around 470 Ma ago, suggesting the existence of a 4 × 6mer at that time. Subsequently, independent gene duplication events gave rise to the other distinct subunits in each of the 8 × 6mer hemocyanin of Xiphosura and the 4 × 6mer of Arachnida. The hemocyanin sequences were used to infer the evolutionary history of chelicerates. The phylogenetic trees support a basal position of Pycnogonida, a sister group relationship of Xiphosura and Arachnida, and a sister group relationship of the whip scorpions and the whip spiders.</p> <p>Conclusion</p> <p>Formation of a complex hemocyanin oligomer commenced early in the evolution of euchelicerates. A 4 × 6mer hemocyanin consisting of seven subunit types is conserved in most arachnids since more than 400 Ma, although some entelegyne spiders display selective subunit loss and independent oligomerization. Hemocyanins also turned out to be a good marker to trace chelicerate evolution, which is, however, limited by the loss of hemocyanin in some taxa. The molecular clock calculations were in excellent agreement with the fossil record, also demonstrating the applicability of hemocyanins for such approach.</p

The polyphyly of Plasmodium: Comprehensive phylogenetic analyses of the malaria parasites (Order Haemosporida) reveal widespread taxonomic conflict

© 2018 The Authors. The evolutionary relationships among the apicomplexan blood pathogens known as the malaria parasites (order Haemosporida), some of which infect nearly 200 million humans each year, has remained a vexing phylogenetic problem due to limitations in taxon sampling, character sampling and the extreme nucleotide base composition biases that are characteristic of this clade. Previous phylogenetic work on the malaria parasites has often lacked sufficient representation of the broad taxonomic diversity within the Haemosporida or the multi-locus sequence data needed to resolve deep evolutionary relationships, rendering our understanding of haemosporidian lifehistory evolution and the origin of the human malaria parasites incomplete. Here we present the most comprehensive phylogenetic analysis of the malaria parasites conducted to date, using samples from a broad diversity of vertebrate hosts that includes numerous enigmatic and poorly known haemosporidian lineages in addition to genome-wide multi-locus sequence data. We find that if base composition differences were corrected for during phylogenetic analysis, we recovered a well-supported topology indicating that the evolutionary history of the malaria parasites was characterized by a complex series of transitions in life-history strategies and host usage. Notably we find that Plasmodium, the malaria parasite genus that includes the species of human medical concern, is polyphyletic with the life-history traits characteristic of this genus having evolved in a dynamic manner across the phylogeny. We find support for multiple instances of gain and loss of asexual proliferation in host blood cells and production of haemozoin pigment, two traits that have been used for taxonomic classification as well as considered to be important factors for parasite virulence and used as drug targets. Lastly, our analysis illustrates the need for a widespread reassessment of malaria parasite taxonomy

The taming of an impossible child: a standardized all-in approach to the phylogeny of Hymenoptera using public database sequences

<p>Abstract</p> <p>Background</p> <p>Enormous molecular sequence data have been accumulated over the past several years and are still exponentially growing with the use of faster and cheaper sequencing techniques. There is high and widespread interest in using these data for phylogenetic analyses. However, the amount of data that one can retrieve from public sequence repositories is virtually impossible to tame without dedicated software that automates processes. Here we present a novel bioinformatics pipeline for downloading, formatting, filtering and analyzing public sequence data deposited in GenBank. It combines some well-established programs with numerous newly developed software tools (available at <url>http://software.zfmk.de/</url>).</p> <p>Results</p> <p>We used the bioinformatics pipeline to investigate the phylogeny of the megadiverse insect order Hymenoptera (sawflies, bees, wasps and ants) by retrieving and processing more than 120,000 sequences and by selecting subsets under the criteria of compositional homogeneity and defined levels of density and overlap. Tree reconstruction was done with a partitioned maximum likelihood analysis from a supermatrix with more than 80,000 sites and more than 1,100 species. In the inferred tree, consistent with previous studies, "Symphyta" is paraphyletic. Within Apocrita, our analysis suggests a topology of Stephanoidea + (Ichneumonoidea + (Proctotrupomorpha + (Evanioidea + Aculeata))). Despite the huge amount of data, we identified several persistent problems in the Hymenoptera tree. Data coverage is still extremely low, and additional data have to be collected to reliably infer the phylogeny of Hymenoptera.</p> <p>Conclusions</p> <p>While we applied our bioinformatics pipeline to Hymenoptera, we designed the approach to be as general as possible. With this pipeline, it is possible to produce phylogenetic trees for any taxonomic group and to monitor new data and tree robustness in a taxon of interest. It therefore has great potential to meet the challenges of the phylogenomic era and to deepen our understanding of the tree of life.</p

predicted amino acids

Fasta files containing the predicted amino acid sequences based on the extracted contigs. Sequences from each Assembly are stored in a separate file

dataset 1 superalignment in FASTA format

Concatenated superalignment of all 1420 single gene amino acid alignments of dataset 1 after processing by Gblocks

Data from: Parasite infection of public databases: a data mining approach to identify apicomplexan contaminations in animal genome and transcriptome assemblies

Background: Contaminations from various exogenous sources are a common problem in next-generation sequencing. Another possible source of contaminating DNA are endogenous parasites. On the one hand, undiscovered contaminations of animal sequence assemblies may lead to erroneous interpretation of data; on the other hand, when identified, parasite-derived sequences may provide a valuable source of information. Results: Here we show that sequences deriving from apicomplexan parasites can be found in many animal genome and transcriptome projects, which in most cases derived from an infection of the sequenced host specimen. The apicomplexan sequences were extracted from the sequence assemblies using a newly developed bioinformatic pipeline (ContamFinder) and tentatively assigned to distinct taxa employing phylogenetic methods. We analysed 920 assemblies and found 20,907 contigs of apicomplexan origin in 51 of the datasets. The contaminating species were identified as members of the apicomplexan taxa Gregarinasina, Coccidia, Piroplasmida, and Haemosporida. For example, in the platypus genome assembly, we found a high number of contigs derived from a piroplasmid parasite (presumably Theileria ornithorhynchi). For most of the infecting parasite species, no molecular data had been available previously, and some of the datasets contain sequences representing large amounts of the parasite’s gene repertoire. Conclusion: Our study suggests that parasite-derived contaminations represent a valuable source of information that can help to discover and identify new parasites, and provide information on previously unknown host-parasite interactions. We, therefore, argue that uncurated assembly data should routinely be made available in addition to the final assemblies

dataset 2 single genes

Fasta files containing the single gene amino acid alignments of dataset 2 prior to processing by Gblock

mitochondrial sequences from gorilla Plasmodium in FASTA format

Nucleotide alignment of mitochondrial Plasmodium sequences including two sequences that were extraceted from the gorilla genome. The alignment is based on data from Liu et al. (2010) and only contains sequences from Clades G1 and C1

dataset 2 superalignment in FASTA format

Concatenated superalignment of all 301 single gene amino acid alignments of dataset 2 after processing by Gblocks

dataset 2 single genes after gblocks

Fasta files containing the single gene amino acid alignments of dataset 2 after processing by Gblocks