Fur microbiome as a putative source of symbiotic bacteria in sucking lice.

Symbiosis between insects and bacteria has been established countless times. While it is well known that the symbionts originated from a variety of different bacterial taxa, it is usually difficult to determine their environmental source and a route of their acquisition by the host. In this study, we address this question using a model of Neisseriaceae symbionts in rodent lice. These bacteria established their symbiosis independently with different louse taxa (Polyplax, Hoplopleura, Neohaematopinus), most likely from the same environmental source. We first applied amplicon analysis to screen for candidate source bacterium in the louse environment. Since lice are permanent ectoparasites, often specific to the particular host, we screened various microbiomes associated with three rodent species (Microtus arvalis, Clethrionomys glareolus, and Apodemus flavicollis). The analyzed samples included fur, skin, spleen, and other ectoparasites sampled from these rodents. The fur microbiome data revealed a Neisseriaceae bacterium, closely related to the known louse symbionts. The draft genomes of the environmental Neisseriaceae, assembled from all three rodent hosts, converged to a remarkably small size of approximately 1.4 Mbp, being even smaller than the genomes of the related symbionts. Our results suggest that the rodent fur microbiome can serve as a source for independent establishment of bacterial symbiosis in associated louse species. We further propose a hypothetical scenario of the genome evolution during the transition of a free-living bacterium to the member of the rodent fur-associated microbiome and subsequently to the facultative and obligate louse symbionts.

Division of labor within psyllids: metagenomics reveals an ancient dual endosymbiosis with metabolic complementarity in the genus Cacopsylla.

IMPORTANCE: Heritable beneficial bacterial endosymbionts have been crucial for the evolutionary success of numerous insects by enabling the exploitation of nutritionally limited food sources. Herein, we describe a previously unknown dual endosymbiosis in the psyllid genus Cacopsylla, consisting of the primary endosymbiont "Candidatus Carsonella ruddii" and a co-occurring Enterobacteriaceae bacterium for which we propose the name "Candidatus Psyllophila symbiotica." Its localization within the bacteriome and its small genome size confirm that Psyllophila is a co-primary endosymbiont widespread within the genus Cacopsylla. Despite its highly eroded genome, Psyllophila perfectly complements the tryptophan biosynthesis pathway that is incomplete in the co-occurring Carsonella. Moreover, the genome of Psyllophila is almost as small as Carsonella's, suggesting an ancient dual endosymbiosis that has now reached a precarious stage where any additional gene loss would make the system collapse. Hence, our results shed light on the dynamic interactions of psyllids and their endosymbionts over evolutionary time.

Arsenophonus symbiosis with louse flies: multiple origins, coevolutionary dynamics, and metabolic significance.

IMPORTANCE: Insects that live exclusively on vertebrate blood utilize symbiotic bacteria as a source of essential compounds, e.g., B vitamins. In louse flies, the most frequent symbiont originated in genus Arsenophonus, known from a wide range of insects. Here, we analyze genomic traits, phylogenetic origins, and metabolic capacities of 11 Arsenophonus strains associated with louse flies. We show that in louse flies, Arsenophonus established symbiosis in at least four independent events, reaching different stages of symbiogenesis. This allowed for comparative genomic analysis, including convergence of metabolic capacities. The significance of the results is twofold. First, based on a comparison of independently originated Arsenophonus symbioses, it determines the importance of individual B vitamins for the insect host. This expands our theoretical insight into insect-bacteria symbiosis. The second outcome is of methodological significance. We show that the comparative approach reveals artifacts that would be difficult to identify based on a single-genome analysis.

Gypsum endolithic phototrophs under moderate climate (Southern Sicily): their diversity and pigment composition.

In this study, we used microscopic, spectroscopic, and molecular analysis to characterize endolithic colonization in gypsum (selenites and white crystalline gypsum) from several sites in Sicily. Our results showed that the dominant microorganisms in these environments are cyanobacteria, including: Chroococcidiopsis sp., Gloeocapsopsis pleurocapsoides, Gloeocapsa compacta, and Nostoc sp., as well as orange pigmented green microalgae from the Stephanospherinia clade. Single cell and filament sequencing coupled with 16S rRNA amplicon metagenomic profiling provided new insights into the phylogenetic and taxonomic diversity of the endolithic cyanobacteria. These organisms form differently pigmented zones within the gypsum. Our metagenomic profiling also showed differences in the taxonomic composition of endoliths in different gypsum varieties. Raman spectroscopy revealed that carotenoids were the most common pigments present in the samples. Other pigments such as gloeocapsin and scytonemin were also detected in the near-surface areas, suggesting that they play a significant role in the biology of endoliths in this environment. These pigments can be used as biomarkers for basic taxonomic identification, especially in case of cyanobacteria. The findings of this study provide new insights into the diversity and distribution of phototrophic microorganisms and their pigments in gypsum in Southern Sicily. Furthemore, this study highlights the complex nature of endolithic ecosystems and the effects of gypsum varieties on these communities, providing additional information on the general bioreceptivity of these environments.

Microbiomes of Blood-Feeding Triatomines in the Context of Their Predatory Relatives and the Environment.

The importance of gut microbiomes has become generally recognized in vector biology. This study addresses microbiome signatures in North American Triatoma species of public health significance (vectors of Trypanosoma cruzi) linked to their blood-feeding strategy and the natural habitat. To place the Triatoma-associated microbiomes within a complex evolutionary and ecological context, we sampled sympatric Triatoma populations, related predatory reduviids, unrelated ticks, and environmental material from vertebrate nests where these arthropods reside. Along with five Triatoma species, we have characterized microbiomes of five reduviids (Stenolemoides arizonensis, Ploiaria hirticornis, Zelus longipes, and two Reduvius species), a single soft tick species, Ornithodoros turicata, and environmental microbiomes from selected sites in Arizona, Texas, Florida, and Georgia. The microbiomes of predatory reduviids lack a shared core microbiota. As in triatomines, microbiome dissimilarities among species correlate with dominance of a single bacterial taxon. These include Rickettsia, Lactobacillus, "Candidatus Midichloria," and Zymobacter, which are often accompanied by known symbiotic genera, i.e., Wolbachia, "Candidatus Lariskella," Asaia, Gilliamella, and Burkholderia. We have further identified a compositional convergence of the analyzed microbiomes in regard to the host phylogenetic distance in both blood-feeding and predatory reduviids. While the microbiomes of the two reduviid species from the Emesinae family reflect their close relationship, the microbiomes of all Triatoma species repeatedly form a distinct monophyletic cluster highlighting their phylosymbiosis. Furthermore, based on environmental microbiome profiles and blood meal analysis, we propose three epidemiologically relevant and mutually interrelated bacterial sources for Triatoma microbiomes, i.e., host abiotic environment, host skin microbiome, and pathogens circulating in host blood. IMPORTANCE This study places microbiomes of blood-feeding North American Triatoma vectors (Reduviidae) into a broader evolutionary and ecological context provided by related predatory assassin bugs (Reduviidae), another unrelated vector species (soft tick Ornithodoros turicata), and the environment these arthropods coinhabit. For both vectors, microbiome analyses suggest three interrelated sources of bacteria, i.e., the microbiome of vertebrate nests as their natural habitat, the vertebrate skin microbiome, and the pathobiome circulating in vertebrate blood. Despite an apparent influx of environment-associated bacteria into the arthropod microbiomes, Triatoma microbiomes retain their specificity, forming a distinct cluster that significantly differs from both predatory relatives and ecologically comparable ticks. Similarly, within the related predatory Reduviidae, we found the host phylogenetic distance to underlie microbiome similarities.

Microbiome Structure of a Wild Drosophila Community along Tropical Elevational Gradients and Comparison to Laboratory Lines.

Variation along environmental gradients in host-associated microbial communities is not well understood compared to free-living microbial communities. Because elevational gradients may serve as natural proxies for climate change, understanding patterns along these gradients can inform our understanding of the threats hosts and their symbiotic microbes face in a warming world. In this study, we analyzed bacterial microbiomes from pupae and adults of four Drosophila species native to Australian tropical rainforests. We sampled wild individuals at high and low elevations along two mountain gradients to determine natural diversity patterns. Further, we sampled laboratory-reared individuals from isofemale lines established from the same localities to see if any natural patterns are retained in the lab. In both environments, we controlled for diet to help elucidate other deterministic patterns of microbiome composition. We found small but significant differences in Drosophila bacterial community composition across elevation, with some notable taxonomic differences between different Drosophila species and sites. Further, we found that field-collected fly pupae had significantly richer microbiomes than laboratory-reared pupae. We also found similar microbiome composition in both types of provided diet, suggesting that the significant differences found among Drosophila microbiomes are the products of surrounding environments with different bacterial species pools, possibly bound to elevational differences in temperature. Our results suggest that comparative studies between lab and field specimens help reveal the true variability in microbiome communities that can exist within a single species. IMPORTANCE Bacteria form microbial communities inside most higher-level organisms, but we know little about how the microbiome varies along environmental gradients and between natural host populations and laboratory colonies. To explore such effects on insect-associated microbiomes, we studied the gut microbiome in four Drosophila species over two mountain gradients in tropical Australia. We also compared these data to individuals kept in the laboratory to understand how different settings changed microbiome communities. We found that field-sampled individuals had significantly higher microbiome diversity than those from the lab. In wild Drosophila populations, elevation explains a small but significant amount of the variation in their microbial communities. Our study highlights the importance of environmental bacterial sources for Drosophila microbiome composition across elevational gradients and shows how comparative studies help reveal the true flexibility in microbiome communities that can exist within a species.

Murine herpesvirus-68-related growth factors treatment correlates with decrease of p53 and HIF-1α protein levels.

Murine herpesvirus 68 (MHV-68) belongs to the subfamily Gammaherpesvirinae of the family Herpesviridae. This exceptional murine herpesvirus is an excellent model for the study of human gammaherpesvirus infections. Cells infected with MHV-68 under nonpermissive conditions for viral replication produce substances designated as MHV-68 growth factors (MHGF-68), that can cause transformation of the cells, or on the other side, turn transformed cells into normal. It was already proposed, that the MHGF-68 fractions cause transformation, disruption of the cytoskeleton and slower growth of the tumors in nude mice. Here, we examined newly extracted fractions of MHGF-68 designated as F5 and F8. Both fractions proved to inhibit the growth of the spheroids and also tumours induced in nude mice. What more, the fractions caused the decrease of the protein levels of wt p53 and HIF-1α. Decreased levels of p53 and HIF-1α activity leads to decreased vascularization, slower tumour growth, and lower adaptation to hypoxic conditions. This would propose MHGF-68 fractions, or their human herpesvirus equivalents, as a potential anticancer drugs in combined chemotherapy.

Supergroup F Wolbachia with extremely reduced genome: transition to obligate insect symbionts.

BACKGROUND: Wolbachia belong to highly abundant bacteria which are frequently found in invertebrate microbiomes and manifest by a broad spectrum of lifestyles from parasitism to mutualism. Wolbachia supergroup F is a particularly interesting clade as it gave rise to symbionts of both arthropods and nematodes, and some of its members are obligate mutualists. Investigations on evolutionary transitions among the different symbiotic stages have been hampered by a lack of the known diversity and genomic data for the supergroup F members. RESULTS: Based on amplicon screening, short- and long-read WGS approaches, and laser confocal microscopy, we characterize five new supergroup F Wolbachia strains from four chewing lice species. These strains reached different evolutionary stages and represent two remarkably different types of symbiont genomes. Three of the genomes resemble other known members of Wolbachia F supergroup, while the other two show typical signs of ongoing gene inactivation and removal (genome size, coding density, low number of pseudogenes). Particularly, wMeur1, a symbiont fixed in microbiomes of Menacanthus eurysternus across four continents, possesses a highly reduced genome of 733,850 bp. The horizontally acquired capacity for pantothenate synthesis and localization in specialized bacteriocytes suggest its obligate nutritional role. CONCLUSIONS: The genome of wMeur1 strain, from the M. eurysternus microbiome, represents the smallest currently known Wolbachia genome and the first example of Wolbachia which has completed genomic streamlining as known from the typical obligate symbionts. This points out that despite the large amount and great diversity of the known Wolbachia strains, evolutionary potential of these bacteria still remains underexplored. The diversity of the four chewing lice microbiomes indicates that this vast parasitic group may provide suitable models for further investigations. Video Abstract.

Functionalization of decavanadate anion by coordination to cobalt(II): Binding to proteins, cytotoxicity, and water oxidation catalysis.

A series of five decavanadates (V10) using a simple, one-pot synthesis, adhering to the model template: transition metal ion - decavanadate - ligands:(Hnicotinamide)2{[Co(H2O)3(nicotinamide)2]2[µ-V10O28]}.6H2O (1), {[Co(H2O)4(isonicotinamide)2]3}V10O28·4H2O (2), {[Co(H2O)4]2[Co(H2O)2(µ-pyrazinamide)2][µ-V10O28]}·4H2O (3) {[Co(H2O)4(µ-pyrazinamide)]3.V10O28}·4H2O (4), and (NH4)2{[Ni(H2O)4(2-hydroxyethylpyridine)]2}V10O28·2H2O (5) was synthesized. X-ray analysis reveals that 1 and 3 are decavanadato complexes, while 2, 4 and 5 are decavanadate complex salts. Moreover, 3 is the first example of a polymeric decavanadato complex, employing direct coordination with the metal center and the organic ligand, in toto. From the solution studies using 51V NMR spectroscopy, it was decoded that 1 and 3 stay stable in the model buffer solution and aqueous media. Binding to model proteins, cytotoxicity and water oxidation catalysis (WOC) was studied primarily for 1 and 3 and concluded that neither 1 nor 3 have an interaction with the model proteins thaumatin, lysozyme and proteinase K, because of the presence of the organic ligands in the Co(II) center, any further interplay with the proteins was blocked. Cytotoxicity studies reveal that 1 is 40% less toxic (0.05 mM) and 26% less toxic (0.1 mM) than the uncoordinated V10 with human cell lines A549 and HeLa respectively. In WOC, 1 performed superior activity, by evolving 143.37 nmol of O2 which is 700% (9-fold) increase than the uncoordinated V10.

Fitness of mCherry Reporter Tick-Borne Encephalitis Virus in Tick Experimental Models.

The tick-borne encephalitis virus (TBEV) causes a most important viral life-threatening illness transmitted by ticks. The interactions between the virus and ticks are largely unexplored, indicating a lack of experimental tools and systematic studies. One such tool is recombinant reporter TBEV, offering antibody-free visualization to facilitate studies of transmission and interactions between a tick vector and a virus. In this paper, we utilized a recently developed recombinant TBEV expressing the reporter gene mCherry to study its fitness in various tick-derived in vitro cell cultures and live unfed nymphal Ixodes ricinus ticks. The reporter virus was successfully replicated in tick cell lines and live ticks as confirmed by the plaque assay and the mCherry-specific polymerase chain reaction (PCR). Although a strong mCherry signal determined by fluorescence microscopy was detected in several tick cell lines, the fluorescence of the reporter was not observed in the live ticks, corroborated also by immunoblotting. Our data indicate that the mCherry reporter TBEV might be an excellent tool for studying TBEV-tick interactions using a tick in vitro model. However, physiological attributes of a live tick, likely contributing to the inactivity of the reporter, warrant further development of reporter-tagged viruses to study TBEV in ticks in vivo.