New sequencing technologies are providing a large-scale proliferation of sequence data, including complete mitochondrial genomes as a side effect of target capture methods. In this study, we use massively parallel sequencing to provide the nearly complete mitochondrial genome of the ant Octostruma stenognatha. The annotation of the genome revealed an interesting pattern that agrees with a recent deep reorganization in the systematics within the Formicidae family. This is the first mitogenome for the genus in a lineage, where the scarcity of mitochondrial information has restricted our understanding of its evolutionary history. This is a valuable example of the power and velocity with which products from new sequencing technologies can increase our capacity to understand evolutionary biology, especially in non-model species.
Understanding both the role of selection in driving phenotypic change and its underlying genetic basis remain major challenges in evolutionary biology. Here, we use modern tools to revisit a classic system of local adaptation in the North American deer mouse, Peromyscus maniculatus, which occupies two main habitat types: prairie and forest. Using historical collections, we find that forest-dwelling mice have longer tails than those from nonforested habitat, even when we account for individual and population relatedness. Using genome-wide SNP data, we show that mice from forested habitats in the eastern and western parts of their range form separate clades, suggesting that increased tail length evolved independently. We find that forest mice in the east and west have both more and longer caudal vertebrae, but not trunk vertebrae, than nearby prairie forms. By intercrossing prairie and forest mice, we show that the number and length of caudal vertebrae are not correlated in this recombinant population, indicating that variation in these traits is controlled by separate genetic loci. Together, these results demonstrate convergent evolution of the long-tailed forest phenotype through two distinct genetic mechanisms, affecting number and length of vertebrae, and suggest that these morphological changes—either independently or together—are adaptive.
Museum specimens provide a wealth of information to biologists, but obtaining genetic data from formalin-fixed and fluid-preserved specimens remains challenging. While DNA sequences have been recovered from such specimens, most approaches are time-consuming and produce low data quality and quantity. Here, we use a modified DNA extraction protocol combined with high-throughput sequencing to recover DNA from formalin-fixed and fluid-preserved snakes that were collected over a century ago and for which little or no modern genetic materials exist in public collections. We successfully extracted DNA and sequenced ultraconserved elements (x¯ = 2318 loci) from 10 fluid-preserved snakes and included them in a phylogeny with modern samples. This phylogeny demonstrates the general use of such specimens in phylogenomic studies and provides evidence for the placement of enigmatic snakes, such as the rare and never-before sequenced Indian Xylophis stenorhynchus. Our study emphasizes the relevance of museum collections in modern research and simultaneously provides a protocol that may prove useful for specimens that have been previously intractable for DNA sequencing.
Cell-free transcription-translationplatforms havebeen widely utilized to express soluble proteins in basic synthetic biological circuit prototyping. From asynthetic biology point of view, it is critical to express membrane proteins in cell-freetranscription-translationsystems, and use them directly in biocircuits,considering the fact that histidine kinases, G-protein coupled receptors (GPCRs) and other important biosensors are all membraneproteins.Previous studies have expressed membrane proteins in cell-free systems with the help of detergents, liposomes or nanodiscs, but have not demonstrated the ability to prototype circuit behavior for the purpose of testing more complex circuit functions involving membrane-bound proteins. Built on previous efforts, in this work we demonstrated that we could co-translationally express solubilizedand activemembrane proteins in our cell-free TX-TL platform with membrane-like materials. Wefirsttested the expression ofseveral constructs with β1 and β2 adrenergicreceptorsin TX-TL and observed significantinsoluble membraneprotein production.The addition ofnanodiscs to the cell free expression system enabled solubilization of membrane proteins. Nanodisc is lipoprotein-based membrane-like material. The activity of β2 adrenergicreceptor was tested withboth fluorescence and Surface Plasmon Resonance (SPR) binding assays by monitoring the specific binding response ofsmall-molecule binders, carazolol and norepinephrine.Our results suggest that it is promisingto use cell-free expression systems to prototype synthetic biocircuits involvingsingle chain membrane proteinswithout extra procedures. This data made us one step closer to testingcomplex membrane protein circuits in cell-free environment.
Standard phylogenetic methods produce conflicting results for several parts of the tree of life. Here, a new phylogenomic method is presented, which resolves controversial relationships within the Otophysi freshwater fish and several other recalcitrant groups.
Mineralized placental tissue from Late Byzantine Troy enables the detailed reconstruction of genomes of mixed bacterial species responsible for maternal sepsis in the ancient world.
We aimed to develop a pipeline for the bioinformatic analysis and interpretation of NGS data and detection of a wide range of single-nucleotide somatic mutations within tumor DNA. Initially, the NGS reads were submitted to a quality control check by the Cutadapt program. Low-quality 3¢-nucleotides were removed. After that the reads were mapped to the reference genome hg19 (GRCh37.p13) by BWA. The SAMtools program was used for exclusion of duplicates. MuTect was used for SNV calling. The functional effect of SNVs was evaluated using the algorithm, including annotation and evaluation of SNV pathogenicity by SnpEff and analysis of such databases as COSMIC, dbNSFP, Clinvar, and OMIM. The effect of SNV on the protein function was estimated by SIFT and PolyPhen2. Mutation frequencies were obtained from 1000 Genomes and ExAC projects, as well as from our own databases with frequency data. In order to evaluate the pipeline we used 18 breast cancer tumor biopsies. The MYbaits Onconome KL v1.5 Panel (“MYcroarray”) was used for targeted enrichment. NGS was performed on the Illumina HiSeq 2500 platform. As a result, we identified alterations in BRCA1, BRCA2, ATM, CDH1, CHEK2, TP53 genes that affected the sequence of encoded proteins. Our pipeline can be used for effective search and annotation of tumor SNVs. In this study, for the first time, we have tested this pipeline for NGS data analysis of samples from patients of the Russian population. However, further confirmation of efficiency and accuracy of the pipeline is required on NGS data from larger datasets as well as data from several types of solid tumors.
Virulence determines the impact a pathogen has on the fitness of its host, yet current understanding of the evolutionary origins and causes of virulence of many pathogens is surprisingly incomplete. Here, we explore the evolution of Marek’s disease virus (MDV), a herpesvirus commonly afflicting chickens and rarely other avian species. The history of MDV in the 20th century represents an important case study in the evolution of virulence. The severity of MDV infection in chickens has been rising steadily since the adoption of intensive farming techniques and vaccination programs in the 1950s and 1970s respectively. It has remained uncertain, however, which of these factors is causally more responsible for the observed increase in virulence of circulating viruses. We conducted a phylogenomic study to understand the evolution of MDV in the context of dramatic changes to poultry farming and disease control. Our analysis reveals evidence of geographical structuring of MDV strains, with reconstructions supporting the emergence of virulent viruses independently in North America and Eurasia. Of note, the emergence of virulent viruses appears to coincide approximately with the introduction of comprehensive vaccination on both continents. The time-dated phylogeny also indicated that MDV has a mean evolutionary rate of ~1.6 x 10-5 substitutions / site / year. An examination of gene-linked mutations did not identify a strong association between mutational variation and virulence phenotypes, indicating that MDV may evolve readily and rapidly under strong selective pressures, and that multiple genotypic pathways may underlie virulence adaptation in MDV. This article is protected by copyright. All rights reserved.
The aquatic planorbid snail Biomphalaria glabrate is one of the most intensively-studied mollusks due to its role in the transmission of schistosomiasis. Its 916 Mb genome has recently been sequenced and annotated, but it remains poorly assembled. Here we used targeted capture markers to map over 10,000 B. glabrate scaffolds in a linkage cross of 94 F1 offspring, generating 24 linkage groups. We added additional scaffolds to these linkage groups based on linkage disequilibrium analysis of targeted capture and whole-genome sequences of 96 unrelated snails. Our final linkage map consists of 18,613 scaffolds comprising 515 Mb, representing 56% of the genome and 75% of genic and nonrepetitive regions. There are 18 large (>10 Mb) linkage groups, likely representing the expected 18 haploid chromosomes, and more than 50% of the genome has been assigned to linkage groups of at least 17 Mb. Comparisons with other gastropod genomes reveal patterns of synteny and chromosomal rearrangements. Linkage relationships of key immune-relevant genes may help clarify snail-schistosome interactions. By focusing on linkage among genic and nonrepetitive regions, we have generated a useful resource for associating snail phenotypes with causal genes, even in the absence of a complete genome assembly. A similar approach could potentially improve numerous poorly-assembled genomes in other taxa. This map will facilitate future work on this host of a serious human parasite.
The rapid diversification of Myotis bats into more than 100 species is one of the most extensive mammalian radiations available for study. Efforts to understand relationships within Myotis have primarily utilized mitochondrial markers and trees inferred from nuclear markers lacked resolution. Our current understanding of relationships within Myotis is therefore biased towards a set of phylogenetic markers that may not reflect the history of the nuclear genome. To resolve this, we sequenced the full mitochondrial genomes of 37 representative Myotis, primarily from the New World, in conjunction with targeted sequencing of 3648 ultraconserved elements (UCEs). We inferred the phylogeny and explored the effects of concatenation and summary phylogenetic methods, as well as combinations of markers based on informativeness or levels of missing data, on our results. Of the 294 phylogenies generated from the nuclear UCE data, all are significantly different from phylogenies inferred using mitochondrial genomes. Even within the nuclear data, quartet frequencies indicate that around half of all UCE loci conflict with the estimated species tree. Several factors can drive such conflict, including incomplete lineage sorting, introgressive hybridization, or even phylogenetic error. Despite the degree of discordance between nuclear UCE loci and the mitochondrial genome and among UCE loci themselves, the most common nuclear topology is recovered in one quarter of all analyses with strong nodal support. Based on these results, we re-examine the evolutionary history of Myotis to better understand the phenomena driving their unique nuclear, mitochondrial, and biogeographic histories.
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