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Roughly 10% to 15% of insect species host heritable symbiotic bacteria known as endosymbionts. The lice parasitizing mammals rely on endosymbionts to provide essential vitamins absent in their blood meals. Here, we describe two bacterial associates from a louse, Proechinophthirus fluctus, which is an obligate ectoparasite of a marine mammal. One of these is a heritable endosymbiont that is not closely related to endosymbionts of other mammalian lice. Rather, it is more closely related to endosymbionts of the genus Sodalis associated with spittlebugs and feather-chewing bird lice. Localization and vertical transmission of this endosymbiont are also more similar to those of bird lice than to those of other mammalian lice. The endosymbiont genome appears to be degrading in symbiosis; however, it is considerably larger than the genomes of other mammalian louse endosymbionts. These patterns suggest the possibility that this Sodalis endosymbiont might be recently acquired, replacing a now-extinct, ancient endosymbiont. From the same lice, we also identified an abundant bacterium belonging to the genus Rickettsia that is closely related to Rickettsia ricketsii, a human pathogen vectored by ticks. No obvious masses of the Rickettsia bacterium were observed in louse tissues, nor did we find any evidence of vertical transmission, so the nature of its association remains unclear. IMPORTANCE Many insects are host to heritable symbiotic bacteria. These heritable bacteria have been identified from numerous species of parasitic lice. It appears that novel symbioses have formed between lice and bacteria many times, with new bacterial symbionts potentially replacing existing ones. However, little was known about the symbionts of lice parasitizing marine mammals. Here, we identified a heritable bacterial symbiont in lice parasitizing northern fur seals. This bacterial symbiont appears to have been recently acquired by the lice. The findings reported here provide insights into how new symbioses form and how this lifestyle is shaping the symbiont genome.

prior to this study, complete mitochondrial genomes from order thysanoptera were restricted to a single family, the thripidae, resulting in a biased view of their evolution. Here we present the sequences for the mitochondrial genomes of four additional thrips species, adding three extra families and an additional subfamily, thus greatly improving taxonomic coverage. thrips mitochondrial genomes are marked by high rates of gene rearrangement, duplications of the control region and tRnA mutations. Derived features of mitochondrial tRnAs in thrips include gene duplications, anticodon mutations, loss of secondary structures and high gene translocation rates. Duplicated control regions are found in the Aeolothripidae and the 'core' thripinae clade but do not appear to promote gene rearrangement as previously proposed. phylogenetic analysis of thrips mitochondrial sequence data supports the monophyly of two suborders, a sister-group relationship between Stenurothripidae and thripidae, and suggests a novel set of relationships between thripid genera. Ancestral state reconstructions indicate that genome rearrangements are common, with just eight gene blocks conserved between any thrips species and the ancestral insect mitochondrial genome. Conversely, 71 derived rearrangements are shared between at least two species, and 24 of these are unambiguous synapomorphies for clades identified by phylogenetic analysis. While the reconstructed sequence of genome rearrangements among the protein-coding and ribosomal RnA genes could be inferred across the phylogeny, direct inference of phylogeny from rearrangement data in MLGo resulted in a highly discordant set of relationships inconsistent with both sequence-based phylogenies and previous morphological analysis. Given the demonstrated rates of genomic evolution within thrips, extensive sampling is needed to fully understand these phenomena across the order.Complete mitochondrial genomes have been shown to be useful for phylogenetic and evolutionary studies at various taxonomic scales, as they provide more phylogenetic information than individual genes alone 1-4 . The mitochondrial genome of metazoans is typically a circular molecule 14-19 kilobases (kb) in length, that contains a conserved set of 37 genes: 13 protein-coding genes (PCGs), ATPase subunits 6 and 8 (atp6 and atp8), Cytochrome oxidase subunits 1 to 3 (cox1-cox3), cytochrome b (cob), NADH dehydrogenase subunits 1-6 and 4 L (nad1-6 and nad4L); the small and large subunit rRNAs (rrnL and rrnS), 22 transfer RNA (tRNA) genes, and a non-coding control region (CR) which contains initiation sites for transcription and replication 1,5 . In addition to sequence variation, metazoan mitochondrial genomes also exhibit variation in a number of features, such as length, tRNA secondary structure, gene order, and the number and internal structure of control regions 6-8 . These features can provide evidence for evolutionary relationships among taxa at high and/or low taxonomic levels beyond that provided by analysis of mitochondrial seq...

In this paper we construct an atlas that summarizes functional connectivity characteristics of a cognitive process from a population of individuals. The atlas encodes functional connectivity structure in a low-dimensional embedding space that is derived from a diffusion process on a graph that represents correlations of fMRI time courses. The functional atlas is decoupled from the anatomical space, and thus can represent functional networks with variable spatial distribution in a population. In practice the atlas is represented by a common prior distribution for the embedded fMRI signals of all subjects. We derive an algorithm for fitting this generative model to the observed data in a population. Our results in a language fMRI study demonstrate that the method identifies coherent and functionally equivalent regions across subjects. The method also successfully maps functional networks from a healthy population used as a training set to individuals whose language networks are affected by tumors.

Most animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes (“minicircles”) are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species known to have between nine and 20 mitochondrial minicircles per genome. All of these species belong to the same clade (mammalian lice), suggesting a single origin of drastic fragmentation. Nevertheless, other work indicates a lesser degree of fragmentation (2–3 chromosomes/genome) is present in some avian feather lice (Ischnocera: Philopteridae). In this study, we tested for minicircles in four species of the feather louse genus Columbicola (Philopteridae). Using whole genome shotgun sequence data, we applied three different bioinformatic approaches for assembling the Columbicola mitochondrial genome. We further confirmed these approaches by assembling the mitochondrial genome of Pediculus humanus from shotgun sequencing reads, a species known to have minicircles. Columbicola spp. genomes are highly fragmented into 15–17 minicircles between ∼1,100 and ∼3,100 bp in length, with 1–4 genes per minicircle. Subsequent annotation of the minicircles indicated that tRNA arrangements of minicircles varied substantially between species. These mitochondrial minicircles for species of Columbicola represent the first feather lice (Philopteridae) for which minicircles have been found in a full mitochondrial genome assembly. Combined with recent phylogenetic studies of parasitic lice, our results provide strong evidence that highly fragmented mitochondrial genomes, which are otherwise rare across the Tree of Life, evolved multiple times within parasitic lice.