Pseudoscorpion Wolbachia symbionts: diversity and evidence for a new supergroup S.

BACKGROUND: Wolbachia are the most widely spread endosymbiotic bacteria, present in a wide variety of insects and two families of nematodes. As of now, however, relatively little genomic data has been available. The Wolbachia symbiont can be parasitic, as described for many arthropod systems, an obligate mutualist, as in filarial nematodes or a combination of both in some organisms. They are currently classified into 16 monophyletic lineage groups ("supergroups"). Although the nature of these symbioses remains largely unknown, expanded Wolbachia genomic data will contribute to understanding their diverse symbiotic mechanisms and evolution. RESULTS: This report focuses on Wolbachia infections in three pseudoscorpion species infected by two distinct groups of Wolbachia strains, based upon multi-locus phylogenies. Geogarypus minor harbours wGmin and Chthonius ischnocheles harbours wCisc, both closely related to supergroup H, while Atemnus politus harbours wApol, a member of a novel supergroup S along with Wolbachia from the pseudoscorpion Cordylochernes scorpioides (wCsco). Wolbachia supergroup S is most closely related to Wolbachia supergroups C and F. Using target enrichment by hybridization with Wolbachia-specific biotinylated probes to capture large fragments of Wolbachia DNA, we produced two draft genomes of wApol. Annotation of wApol highlights presence of a biotin operon, which is incomplete in many sequenced Wolbachia genomes. CONCLUSIONS: The present study highlights at least two symbiont acquisition events among pseudoscorpion species. Phylogenomic analysis indicates that the Wolbachia from Atemnus politus (wApol), forms a separate supergroup ("S") with the Wolbachia from Cordylochernes scorpioides (wCsco). Interestingly, the biotin operon, present in wApol, appears to have been horizontally transferred multiple times along Wolbachia evolutionary history.

Amblypygid-fungal interactions: The whip spider exoskeleton as a substrate for fungal growth.

Fungi and arthropods represent some of the most diverse organisms on our planet, yet the ecological relationships between them remain largely unknown. In animals, fungal growth on body surfaces is often hazardous and is known to cause mortality. In contrast, here we report the presence of an apparently non-harmful mycobiome on the cuticle of whip spiders (Arachnida: Amblypygi). The associations are not species-specific and involve a diversity of fungal species, including cosmopolitan and local decomposers as well as entomopathogens. We discuss the ecology of the detected fungal species and hypothesize that the thick epicuticular secretion coat of whip spiders (the cerotegument) promotes fungal growth. It is possible that this relationship is beneficial towards the host if it leads to parasite control or chemical camouflage. Our findings, which are the first from this arthropod lineage, indicate that non-pathogenic interactions between arthropods and fungi may be much more widespread than predicted and call for more studies in this area.

Effect of gregarines (Apicomplexa: Sporozoa) on survival and weight loss of Victorwithius similis (Arachnida: Pseudoscorpiones).

Gregarines are common intestinal parasites of numerous invertebrate groups. Their effects on host viability and development have been a matter of debate. Although they may not be lethal to the host, they can be harmless commensals, by affecting adaptive traits, or have a beneficial relationship with the host. This study focused on determining prevalence, intensity, and change in infection intensity over time by septate gregarines, and monitoring the effects on survival and weight loss in the pseudoscorpion Victorwithius similis. Individuals (n=24 females, n=55 males and n=41 tritonymphs) were captured in the field, transported to the vivarium and bred under laboratory conditions. A high prevalence of infection was found, with 77.27% of females, 62.50% of males and 73.53% of tritonymphs harboring intense infections. Of the infected pseudoscorpions, 62% of females, 58% of males and 71% of tritonymphs did not show changes in infection intensity over time. The group that maintained intense infections survived longer than those with less intense infections (χ(2)=8.642; p=0.035). Most of the results obtained indicate that relationship studied between gregarines and the pseudoscorpion V. similis might be a case of commensalism. This would explain why the infection level and prevalence was very high, as well as the apparent lack of direct costs to highly infected individuals those with infections.

Two Trichosporon species isolated from Central-European mygalomorph spiders (Araneae: Mygalomorphae).

Trichosporon (Dikarya: Basidiomycota) is a genus of anamorphic yeasts typically associated with soil and water, although many species are causative agents of diseases in animals and man. Here we provide the first compelling evidence that spiders can be occasionally colonized by at least two Trichosporon species. Trichosporon dulcitum (Berkhout) Weijman 1979 was isolated from the exoskeleton of purse-web spider Atypus piceus, while Trichosporon porosum (Stautz) Middelhoven, Scorzetti & Fell 2001 was isolated from the exoskeleton of purse-web spider Atypus affinis. Both of the species were identified based on DNA sequence analysis of the host specimens displaying macroscopic signs of the superficial white mycosis on their exoskeleton. Only two specimens with macroscopic signs of superficial yeast growth were identified among the 125 individuals of A. affinis, A. piceus and Atypus muralis examined that were collected at various sites throughout the Czech Republic. The consistent burrow microclimate, uninterrupted occupancy of the single burrow for several subsequent years, and presence of prey remnants in the burrow below the purse-web may play a role in the course of infection of the mygalomorphs examined. The phylogenetic relationships of Trichosporon species are analyzed, concluding that association with invertebrates clusters predominantly among four groups of closely related species in independent Trichosporon clades.

Wolbachia strains typing in different geographic population spider, Hylyphantes graminicola (Linyphiidae).

The Wolbachia endosymbiont of spiders has not been extensively examined. In order to investigate the distribution, evolutionary history, and reproductive phenotype of Wolbachia in spiders in China, we tested 11 geographic populations of Hylyphantes graminicola. Wolbachia infection has been detected in each population. 10 Wolbachia strains have been characterized by multilocus sequence typing (MLST). Phylogenetic analyses indicated that eight Wolbachia strains in H. graminicola belonged to supergroup B, and two belonged to supergroup A. No correlation existed between Wolbachia diversity and host's geographic distance. The significant correlation was observed between pairwise distance of H. graminicola COI and genetic divergence of associated Wolbachia strains. We also found that Wolbachia infection frequencies in hosts varied over geographic space.

A divergent Cardinium found in daddy long-legs (Arachnida: Opiliones).

Recent studies indicate that a newly described bacterial endosymbiont, Cardinium, is widespread in arthropods and induces different reproductive manipulations in hosts. In this study, we used a portion of the 16S rRNA gene of the Cardinium to screen 16 Opilionid species from the suborder Palptores. We found the incidence of Cardinium in these Opiliones was significantly higher than in other pooled arthropods (31.2% versus 7.2%, P=0.007). Phylogenetic analyses using maximum parsimony (MP) and Bayesian analysis revealed two distinct clades in Opiliones. One is a divergent monophyletic clade with strong support that has so far not been found in other arthropods, and a second one contains Cardinium both from Opiliones and other arthropods. There is not complete concordance of the Cardinium strains with host phylogeny, suggesting some horizontal movement of the bacteria among Opiliones. Although the divergence in the sequenced 16S rRNA region between the Cardinium infecting Opiliones and Cardinium from other arthropods is greater than among Cardinium found in other arthropods, all are monophyletic with respect to the outgroup bacteria (endosymbionts of Acanthamoeba). Based on high pairwise genetic distances, deep branch, and a distinct phylogenetic grouping, we conclude that some Opiliones harbor a newly discovered Cardinium clade.

Reproductive compensation favours male-killing Wolbachia in a live-bearing host.

Wolbachia are maternally inherited, cellular endosymbionts that can enhance their fitness by biasing host sex ratio in favour of females. Male killing (MK) is an extreme form of sex-ratio manipulation that is selectively advantageous if the self-sacrifice of Wolbachia in males increases transmission through females. In live-bearing hosts, females typically produce more embryos than can be carried to term, and reproductive compensation through maternal resource reallocation from dead males to female embryos could increase the number of daughters born to infected females. Here, we report a new strain of MK Wolbachia (wCsc2) in the pseudoscorpion, Cordylochernes scorpioides, and present the first empirical evidence that reproductive compensation favours the killing of males in a viviparous host. Females infected with the wCsc2 strain produced 26 per cent more and significantly larger daughters than tetracycline-cured females. In contrast to the previously described wCsc1 MK Wolbachia strain in C. scorpioides, wCsc2 infection was not accompanied by an increase in the rate of spontaneous brood abortion. Characterization of the wCsc1 and wCsc2 strains by multi-locus sequence typing and by Wolbachia surface protein (wsp) gene sequencing indicates that the marked divergence between these two MK strains in their impact on host reproductive success, and hence in their potential to spread, has occurred in association with homologous recombination in the wsp gene.

[Bacterial contamination of arthropods in a health facility]. / Bakteriální kontaminace clenovcu ve zdravotnickém zarízení.

At 55 sites of a health institution in July and September 1990 a total of 161 specimens of arthropods were detected, 30 outdoors and 131 on the premises of the health institution. On their bodies 116 bacterial strains were isolated, mostly Gram-negative rods (more than 85%), in particular spp. Enterobacter, Acinetobacter, Klebsiella, Citrobacter and Pseudomonas. Gram-positive cocci accounted for cca 12%, in particular strains of S. haemolyticus and S. hominis. The greatest number of strains was detected on bodies of cockroaches, flies, Chironomus and Tenebrio. In about one third of strains the diffuse disk test revealed resistance to more than three antibiotics. The investigation was supplemented by microbiological examination of strains from a hospital environment (45 smears) and strains from biological material (82 specimens), from patients with nosocomial infections.

Epidemiological role of arthropods detectable in health facilities.

A total of 161 arthropod specimens were collected from 55 sites in a health care facility during July and September 1990. Of the 116 bacterial isolates obtained from their body surfaces 6% were from parasites (mosquitoes), 59% from eusynanthropic arthropods (Tenebrionid beetles, flies, German cockroaches, wasps), 16% from hemisynanthropic arthropods (ants, spiders) and 19% from occasionally encountered insects (non-biting midges, moths, beetles). Most (88%) of the isolated bacteria were Gram-negative rods of the species E. coli, Enterobacter, Klebsiella, Citrobacter, Proteus, Serratia, Pseudomonas and Acinetobacter. Gram-positive cocci accounted for 13% of isolates and were primarily represented by coagulase-negative staphylococci. The highest isolation rates were from body surfaces of flies, German cockroaches, non-biting midges (Chironomids) and Tenebrionid beetles. About one third of all isolates were resistant to more than three antimicrobials using a standard disc diffusion assay. The presence of multiple resistance to antibiotics was observed in two thirds of Enterobacter isolates, namely those of Enterobacter cloacae from the body surface of Germany cockroaches, in 13% of Citrobacter spp and in 8% of Klebsiella spp as well as Acinetobacter calcoaceticus strains. Strains of Morganella and Hafnia species were very infrequent but all of them shared resistance to the antibiotics tested. In contrast, strains of Serratia spp were relatively antibiotic-sensitive. The group of isolated Gram-positive organisms was represented by two strains of Staphylococcus hominis and one strain of Enterococcus sp, all of them were multiply-resistant to antimicrobials.

Overwintering mechanisms of mosquito-borne arboviruses in temperate climates.

It can be concluded from the data cited that transovarial transmission is a plausible explanation for the overwintering of mosquito-borne bunyaviruses of the California serogroup. Vertical transmission of mosquito-borne flaviviruses could explain the overwintering of this group of viruses, but this is far from having been established. At present, the mechanism by which mosquito-borne alphaviruses pass the winter is obscure.