Microbiomes are vast communities of microorganisms and viruses that populate all natural ecosystems. Viruses have been considered to be the most variable component of microbiomes, as supported by virome surveys and examples of high genomic mosaicism. However, recent evidence suggests that the human gut virome is remarkably stable compared with that of other environments. Here, we investigate the origin, evolution and epidemiology of crAssphage, a widespread human gut virus. Through a global collaboration, we obtained DNA sequences of crAssphage from more than one-third of the world's countries and showed that the phylogeography of crAssphage is locally clustered within countries, cities and individuals. We also found fully colinear crAssphage-like genomes in both Old-World and New-World primates, suggesting that the association of crAssphage with primates may be millions of years old. Finally, by exploiting a large cohort of more than 1,000 individuals, we tested whether crAssphage is associated with bacterial taxonomic groups of the gut microbiome, diverse human health parameters and a wide range of dietary factors. We identified strong correlations with different clades of bacteria that are related to Bacteroidetes and weak associations with several diet categories, but no significant association with health or disease. We conclude that crAssphage is a benign cosmopolitan virus that may have coevolved with the human lineage and is an integral part of the normal human gut virome.

• MeSH
• Bacteroidetes klasifikace   genetika   virologie   MeSH
• bakteriofágy klasifikace   genetika   MeSH
• DNA virů genetika   MeSH
• feces virologie   MeSH
• fylogeneze MeSH
• fylogeografie MeSH
• genetická variace MeSH
• koevoluce * MeSH
• lidé MeSH
• primáti virologie   MeSH
• střevní mikroflóra * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

All 100+ bedbug species (Cimicidae) are obligate blood-sucking parasites [1, 2]. In general, blood sucking (hematophagy) is thought to have evolved in generalist feeders adventitiously taking blood meals [3, 4], but those cimicid taxa currently considered ancestral are putative host specialists [1, 5]. Bats are believed to be the ancestral hosts of cimicids [1], but a cimicid fossil [6] predates the oldest known bat fossil [7] by >30 million years (Ma). The bedbugs that parasitize humans [1, 8] are host generalists, so their evolution from specialist ancestors is incompatible with the "resource efficiency" hypothesis and only partially consistent with the "oscillation" hypothesis [9-16]. Because quantifying host shift frequencies of hematophagous specialists and generalists may help to predict host associations when vertebrate ranges expand by climate change [17], livestock, and pet trade in general and because of the previously proposed role of human pre-history in parasite speciation [18-20], we constructed a fossil-dated, molecular phylogeny of the Cimicidae. This phylogeny places ancestral Cimicidae to 115 mya as hematophagous specialists with lineages that later frequently populated bat and bird lineages. We also found that the clades, including the two major current urban pests, Cimex lectularius and C. hemipterus, separated 47 mya, rejecting the notion that the evolutionary trajectories of Homo caused their divergence [18-21]. VIDEO ABSTRACT.

• MeSH
• Chiroptera genetika   parazitologie   MeSH
• Cimicidae genetika   fyziologie   MeSH
• fylogeneze * MeSH
• interakce hostitele a parazita * MeSH
• koevoluce * MeSH
• lidé MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The range of hosts exploited by a parasite is determined by several factors, including host availability, infectivity and exploitability. Each of these can be the target of natural selection on both host and parasite, which will determine the local outcome of interactions, and potentially lead to coevolution. However, geographical variation in host use and specificity has rarely been investigated. Maculinea (= Phengaris) butterflies are brood parasites of Myrmica ants that are patchily distributed across the Palæarctic and have been studied extensively in Europe. Here, we review the published records of ant host use by the European Maculinea species, as well as providing new host ant records for more than 100 sites across Europe. This comprehensive survey demonstrates that while all but one of the Myrmica species found on Maculinea sites have been recorded as hosts, the most common is often disproportionately highly exploited. Host sharing and host switching are both relatively common, but there is evidence of specialization at many sites, which varies among Maculinea species. We show that most Maculinea display the features expected for coevolution to occur in a geographic mosaic, which has probably allowed these rare butterflies to persist in Europe. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

• MeSH
• druhová specificita MeSH
• Formicidae parazitologie   MeSH
• hnízdění * MeSH
• interakce hostitele a parazita * MeSH
• koevoluce * MeSH
• motýli fyziologie   MeSH
• symbióza * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH

During a survey in agricultural fields of the sub-humid region of Meerut district, India, two strains of entomopathogenic nematodes, labelled CS31 and CS32, were isolated using the Galleria baiting technique. Based on morphological and morphometric studies, and molecular data, the nematodes were identified as Steinernema pakistanense, making this finding the first report of this species from India. For the first time, we performed a molecular and biochemical characterization of the bacterial symbiont of S. pakistanense. Furthermore, a co-phylogenetic analysis of the bacteria from the monophyletic clade containing a symbiont of S. pakistanense, together with their nematode hosts, was conducted, to test the degree of nematode-bacteria co-speciation. Both isolates were also tested in a laboratory assay for pathogenicity against two major pests, Helicoverpa armigera and Spodoptera litura. The morphology of the Indian isolates corresponds mainly to the original description, with the only difference being the absence of a mucron in first-generation females and missing epiptygmata in the second generation. The sequences of bacterial recA and gyrB genes have shown that the symbiont of S. pakistanense is closely related to Xenorhabdus indica, which is associated with some other nematodes from the 'bicornutum' group. Co-phylogenetic analysis has shown a remarkable congruence between the nematode and bacterial phylogenies, suggesting that, in some lineages within the Steinernema / Xenorhabdus complex, the nematodes and bacteria have undergone co-speciation. In the virulence assay, both strains caused a 100% mortality of both tested insects after 48 h, even at the lowest doses of 25 infective juveniles per insect, suggesting that S. pakistanense could be considered for use in the biocontrol of these organisms in India.

• MeSH
• dezinsekce MeSH
• fylogeneze * MeSH
• koevoluce * MeSH
• larva růst a vývoj   parazitologie   MeSH
• můry růst a vývoj   parazitologie   MeSH
• symbióza * MeSH
• Tylenchida anatomie a histologie   klasifikace   mikrobiologie   patogenita   MeSH
• virulence MeSH
• Xenorhabdus klasifikace   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Indie MeSH

In the last two decades, the advent of molecular methods has revealed a remarkable diversity of rickettsiae (Rickettsiales: Rickettsiaceae) in invertebrates. Several species of these obligate intracellular bacteria are known to cause human infections, hence more attention has been directed towards human-biting ectoparasites. A spotted fever group Rickettsia sp. was previously detected in Ixodes lividus ticks (Ixodidae) associated with sand martins (Hirundinidae: Riparia riparia). In order to identify whether this rickettsia varies among isolated tick populations, a total of 1758 I. lividus ticks and five Ixodes ricinus ticks (Ixodidae) were collected in the Czech Republic and 148 I. lividus ticks were collected in Belgium, from nests of sand martins, European bee-eaters (Meropidae: Merops apiaster), Eurasian tree sparrows (Passeridae: Passer montanus), and from captured sand martins. We screened 165 and 78 I. lividus ticks (from the Czech Republic and Belgium, respectively) and all five I. ricinus ticks for the presence of rickettsial DNA. Only I. lividus samples were positive for Rickettsia vini, a spotted fever group rickettsia that commonly infects the tree-hole tick Ixodes arboricola (Ixodidae). Maximum likelihood analysis of the rickettsial sequences showed that the most closely related organism to R. vini corresponds to an uncharacterized rickettsia detected in Argas lagenoplastis (Argasidae), a nidicolous soft tick of the fairy martin (Hirundinidae: Petrochelidon ariel) in Australia. The observed variability of R. vini sequences from isolated tick populations was low; all 85 sequenced samples were identical to each other in five out of six partial rickettsial genes, except for the sca4 sequence (99.9% identity, 808/809 nt) that differed in I. lividus ticks from two sampling sites in the Czech Republic.

• MeSH
• Argasidae mikrobiologie   MeSH
• DNA bakterií genetika   MeSH
• fylogeneze MeSH
• infestace klíšťaty epidemiologie   veterinární   MeSH
• klíště mikrobiologie   MeSH
• koevoluce genetika   MeSH
• lidé MeSH
• nemoci ptáků mikrobiologie   MeSH
• nymfa MeSH
• pravděpodobnostní funkce MeSH
• ptáci parazitologie   MeSH
• Rickettsia klasifikace   genetika   izolace a purifikace   MeSH
• rickettsiové infekce epidemiologie   mikrobiologie   veterinární   MeSH
• skvrnité horečky epidemiologie   mikrobiologie   veterinární   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Belgie epidemiologie   MeSH
• Česká republika epidemiologie   MeSH

Legionellaceae are intracellular bacteria known as important human pathogens. In the environment, they are mainly found in biofilms associated with amoebas. In contrast to the gammaproteobacterial family Enterobacteriaceae, which established a broad spectrum of symbioses with many insect taxa, the only instance of legionella-like symbiont has been reported from lice of the genus Polyplax. Here, we sequenced the complete genome of this symbiont and compared its main characteristics to other Legionella species and insect symbionts. Based on rigorous multigene phylogenetic analyses, we confirm this bacterium as a member of the genus Legionella and propose the name Candidatus Legionella polyplacis, sp.n. We show that the genome of Ca. Legionella polyplacis underwent massive degeneration, including considerable size reduction (529.746 bp, 484 protein coding genes) and a severe decrease in GC content (23%). We identify several possible constraints underlying the evolution of this bacterium. On one hand, Ca. Legionella polyplacis and the louse symbionts Riesia and Puchtella experienced convergent evolution, perhaps due to adaptation to similar hosts. On the other hand, some metabolic differences are likely to reflect different phylogenetic positions of the symbionts and hence availability of particular metabolic function in the ancestor. This is exemplified by different arrangements of thiamine metabolism in Ca. Legionella polyplacis and Riesia. Finally, horizontal gene transfer is shown to play a significant role in the adaptive and diversification process. Particularly, we show that Ca. L. polyplacis horizontally acquired a complete biotin operon (bioADCHFB) that likely assisted this bacterium when becoming an obligate mutualist.

• MeSH
• Anoplura genetika   mikrobiologie   MeSH
• fyziologická adaptace MeSH
• genom bakteriální genetika   MeSH
• koevoluce MeSH
• Legionella klasifikace   genetika   fyziologie   MeSH
• molekulární evoluce * MeSH
• přenos genů horizontální MeSH
• sekvenční analýza DNA MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Polymorphic microsatellite loci were characterised for two louse species, the anopluran Polyplax serrata Burmeister, 1839, parasitising Eurasian field mice of the genus Apodemus Kaup, and the amblyceran Myrsidea nesomimi Palma et Price, 2010, found on mocking birds endemic to the Galápagos Islands. Evolutionary histories of the two parasites show complex patterns influenced both by their geographic distribution and through coevolution with their respective hosts, which renders them prospective evolutionary models. In P. serrata, 16 polymorphic loci were characterised and screened across 72 individuals from four European populations that belong to two sympatric mitochondrial lineages differing in their breadth of host-specificity. In M. nesomimi, 66 individuals from three island populations and two host species were genotyped for 15 polymorphic loci. The observed heterozygosity varied from 0.05 to 0.9 in P. serrata and from 0.0 to 0.96 in M. nesomimi. Deviations from the Hardy-Weinberg equilibrium were frequently observed in the populations of both parasites. Fst distances between tested populations correspond with previous phylogenetic data, suggesting the microsatellite loci are an informative resource for ecological and evolutionary studies of the two parasites.

• Klíčová slova
• polymorfismus,
• MeSH
• biologická evoluce MeSH
• genotypizační techniky MeSH
• heterozygot MeSH
• hostitelská specificita MeSH
• koevoluce MeSH
• mikrosatelitní repetice MeSH
• Murinae parazitologie   MeSH
• oligonukleotidy MeSH
• Passeriformes parazitologie   MeSH
• Phthiraptera * klasifikace   MeSH
• polymerázová řetězová reakce MeSH
• populační genetika metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Ekvádor MeSH
• Evropa MeSH