Trophic and symbiotic links between obligate-glacier water bears (Tardigrada) and cryoconite microorganisms

Insights into biodiversity and trophic webs are important for understanding ecosystem functions. Although the surfaces of glaciers are one of the most productive and biologically diverse parts of the cryosphere, the links between top consumers, their diet and microbial communities are poorly understood. In this study, for the first time we investigated the relationships between bacteria, fungi and other microeukaryotes as they relate to tardigrades, microscopic metazoans that are top consumers in cryoconite, a biologically rich and productive biogenic sediment found on glacier surfaces. Using metabarcoding (16S rDNA for bacteria, ITS1 for fungi, and 18S rDNA for other microeukaryotes), we analyzed the microbial community structures of cryoconite and compared them with the community found in both fully fed and starved tardigrades. The community structure of each microbial group (bacteria, fungi, microeukaryotes) were similar within each host group (cryoconite, fully fed tardigrades and starved tardigrades), and differed significantly between groups, as indicated by redundancy analyses. The relative number of operational taxonomic units (ZOTUs, OTUs) and the Shannon index differed significantly between cryoconite and tardigrades. Species indicator analysis highlighted a group of microbial taxa typical of both fully fed and starved tardigrades (potential commensals), like the bacteria of the genera Staphylococcus and Stenotrophomonas, as well as a group of taxa typical of both cryoconite and fully fed tardigrades (likely part of the tardigrade diet; bacteria Flavobacterium sp., fungi Preussia sp., algae Trebouxiophyceae sp.). Tardigrades are consumers of bacteria, fungi and other microeukaryotes in cryoconite and, being hosts for diverse microbes, their presence can enrich the microbiome of glaciers.

Avian haemosporidian parasites of accipitriform raptors

Background The order Accipitriformes comprises the largest group of birds of prey with 260 species in four families. So far, 21 haemosporidian parasite species have been described from or reported to occur in accipitriform birds. Only five of these parasite species have been characterized molecular genetically. The first part of this study involved molecular genetic screening of accipitriform raptors from Austria and Bosnia-Herzegovina and the first chromogenic in situ hybridization approach targeting parasites in this host group. The aim of the second part of this study was to summarize the CytB sequence data of haemosporidian parasites from accipitriform raptors and to visualize the geographic and host distribution of the lineages. Methods Blood and tissue samples of 183 accipitriform raptors from Austria and Bosnia-Herzegovina were screened for Plasmodium, Haemoproteus and Leucocytozoon parasites by nested PCR, and tissue samples of 23 PCR-positive birds were subjected to chromogenic in situ hybridization using genus-specific probes targeting the parasites’ 18S rRNAs. All published CytB sequence data from accipitriform raptors were analysed, phylogenetic trees were calculated, and DNA haplotype network analyses were performed with sequences from clades featuring multiple lineages detected in this host group. Results Of the 183 raptors from Austria and Bosnia-Herzegovina screened by PCR and sequencing, 80 individuals (44%) were infected with haemosporidian parasites. Among the 39 CytB lineages detected, 18 were found for the first time in the present study. The chromogenic in situ hybridization revealed exo-erythrocytic tissue stages of Leucocytozoon parasites belonging to the Leucocytozoon toddi species group in the kidneys of 14 infected birds. The total number of CytB lineages recorded in accipitriform birds worldwide was 57 for Leucocytozoon, 25 for Plasmodium, and 21 for Haemoproteus. Conclusion The analysis of the DNA haplotype networks allowed identifying numerous distinct groups of lineages, which have not yet been linked to morphospecies, and many of them likely belong to yet undescribed parasite species. Tissue stages of Leucocytozoon parasites developing in accipitriform raptors were discovered and described. The majority of Leucocytozoon and Haemoproteus lineages are specific to this host group, but most Plasmodium lineages were found in birds of other orders. This might indicate local transmission from birds kept at the same facilities (raptor rescue centres and zoos), likely resulting in abortive infections. To clarify the taxonomic and systematic problems, combined morphological and molecular genetic analyses on a wider range of accipitriform host species are needed.

Host-to-Host Group A Streptococcus Transmission Causes Infection of the Lamina Propria but not Epithelium of the Upper Respiratory Tract in MyD88-Deficient Mice

To understand protective immune responses against the onset of Group A Streptococcus respiratory infection, we investigated whether MyD88 KO mice were susceptible to acute infection through transmission. After commingling with mice that had intranasal GAS inoculation, MyD88 -/- recipient mice had increased GAS loads in the nasal cavity and throat that reached a mean throat colonization of 6.3 x 10 6 cfu/swab and mean GAS load of 5.2 x 10 8 cfu in the nasal cavity on day 7. Beyond day 7, MyD88 -/- recipient mice became moribund, with mean 1.6 x 10 7 cfu/swab and 2.5 x 10 9 cfu GAS in the throat and nasal cavity, respectively. Systemic GAS infection occurred a couple of days after the upper respiratory infection. GAS infects the lip, gingival sulcus of the incisor teeth, the lamina propria of the turbinate but not the nasal cavity and nasopharyngeal tract epithelia, and C57BL/6J recipient mice had no or low levels of GAS in the nasal cavity and throat. Direct nasal GAS inoculation of MyD88 -/- mice caused GAS infection mainly in the lamina propria of the turbinate. In contrast, C57BL/6J mice with GAS inoculation had GAS bacteria in the nasal cavity but not in the lamina propria of the turbinates. Thus, MyD88 -/- mice are highly susceptible to acute and lethal GAS infection through transmission, and MyD88 signaling is critical for protection of the respiratory tract lamina propria but not nasal and nasopharyngeal epithelia against GAS infection.

Clinical variations observed among the main hemoparasitosis caused by Rhipicephalus sanguineus in dogs

Hemoparasitosis are diseases of great importance in the practice of a small animal’s veterinarian, due to their high number of cases in the clinical routine of these species, and the wide occurrence of their vectors. Related to hemoparasitosis in dogs, the tick Rhipicephalus sanguineus has the greatest importance due to parasitizing dogs, perpetuating hemoparasitosis in this host group. The present work describes a literature review about the three main hemoparasitosis in the routine of a veterinarian in Brazil, ehrlichiosis, caused by Ehrlichia canis, babesiosis caused by the protozoa Babesia canis and Babesia gibsoni, and anaplasmosis caused by Anaplasma platys, comparing them regarding the differences between clinical signs and laboratory alterations, such as the different types of anemia caused by these conditions that culminate in clinical signs related to them. It also aims to describe the similarity in the diagnostic techniques used and infection treatments, which in all cases is used tetracycline, the most commonly used is doxycycline, and highlight the need for further studies about this topic.

Linking Zoonosis Emergence to Farmland Invasion by Fluctuating Herbivores: Common Vole Populations and Tularemia Outbreaks in NW Spain

The expansion and intensification of agriculture are driving profound changes in ecosystems worldwide, favoring the (re)emergence of many human infectious diseases. Muroid rodents are a key host group for zoonotic infectious pathogens and frequently invade farming environments, promoting disease transmission and spillover. Understanding the role that fluctuating populations of farm dwelling rodents play in the epidemiology of zoonotic diseases is paramount to improve prevention schemes. Here, we review a decade of research on the colonization of farming environments in NW Spain by common voles (Microtus arvalis) and its public health impacts, specifically periodic tularemia outbreaks in humans. The spread of this colonizing rodent was analogous to an invasion process and was putatively triggered by the transformation and irrigation of agricultural habitats that created a novel terrestrial-aquatic interface. This irruptive rodent host is an effective amplifier for the Francisella tularensis bacterium during population outbreaks, and human tularemia episodes are tightly linked in time and space to periodic (cyclic) variations in vole abundance. Beyond the information accumulated to date, several key knowledge gaps about this pathogen-rodent epidemiological link remain unaddressed, namely (i) did colonizing vole introduce or amplified pre-existing F. tularensis? (ii) which features of the “Francisella—Microtus” relationship are crucial for the epidemiology of tularemia? (iii) how virulent and persistent F. tularensis infection is for voles under natural conditions? and (iv) where does the bacterium persist during inter-epizootics? Future research should focus on more integrated, community-based approaches in order to understand the details and dynamics of disease circulation in ecosystems colonized by highly fluctuating hosts.

Genome-Wide Association Mapping of bc-1 and bc-u Reveals Candidate Genes and New Adjustments to the Host-Pathogen Interaction for Resistance to Bean Common Mosaic Necrosis Virus in Common Bean

Bean common mosaic necrosis virus (BCMNV) is a major disease in common bean (Phaseolus vulgaris L.). Host plant resistance is the primary disease control. We sought to identify candidate genes to better understand the host-pathogen interaction and develop tools for marker-assisted selection (MAS). A genome-wide association study (GWAS) approach using 182 lines from a race Durango Diversity Panel (DDP) challenged by BCMNV isolates NL-8 [Pathogroup (PG)-III] and NL-3 (PG-VI), and genotyped with 1.26 million single-nucleotide polymorphisms (SNPs), revealed significant peak regions on chromosomes Pv03 and Pv05, which correspond to bc-1 and bc-u resistance gene loci, respectively. Three candidate genes were identified for NL-3 and NL-8 resistance. Side-by-side receptor-like protein kinases (RLKs), Phvul.003G038700 and Phvul.003G038800 were candidate genes for bc-1. These RLKs were orthologous to linked RLKs associated with virus resistance in soybean (Glycine max). A basic Leucine Zipper (bZIP) transcription factor protein is the candidate gene for bc-u. bZIP protein gene Phvul.005G124100 carries a unique non-synonymous mutation at codon 14 in the first exon (Pv05: 36,114,516 bases), resulting in a premature termination codon that causes a nonfunctional protein. SNP markers for bc-1 and bc-u and new markers for I and bc-3 genes were used to genotype the resistance genes underpinning BCMNV phenotypes in the DDP, host group (HG) differentials, and segregating F3 families. Results revealed major adjustments to the current host-pathogen interaction model: (i) there is only one resistance allele bc-1 for the Bc-1 locus, and differential expression of the allele is based on presence vs. absence of bc-u; (ii) bc-1 exhibits dominance and incomplete dominance; (iii) bc-1 alone confers resistance to NL-8; (iv) bc-u was absent from HGs 2, 4, 5, and 7 necessitating a new gene symbol bc-ud to reflect this change; (v) bc-ud alone delays susceptible symptoms, and when combined with bc-1 enhanced resistance to NL-3; and (vi) bc-ud is on Pv05, not Pv03 as previously thought. These candidate genes, markers, and adjustments to the host-pathogen interaction will facilitate breeding for resistance to BCMNV and related Bean common mosaic virus (BCMV) in common bean.

The interplay between host biogeography and phylogeny in structuring diversification of the feather louse genus Penenirmus

Parasite diversification is influenced by many of the same factors that affect speciation of free-living organisms, such as biogeographic barriers. However, the ecology and evolution of the host lineage also has a major impact on parasite speciation. Here we explore the interplay between biogeography and host-association on the pattern of diversification in a group of ectoparasitic lice (Insecta: Phthiraptera: Penenirmus) that feeds on the feathers of woodpeckers, barbets, and honeyguides (Piciformes) and some songbirds (Passeriformes). We use whole genome sequencing of 41 ingroup and 12 outgroup samples to develop a phylogenomic dataset of DNA sequences from a reference set of 2,395 single copy ortholog genes, for a total of nearly four million aligned base positions. The phylogenetic trees resulting from both concatenated and gene-tree/species-tree coalescent analyses were nearly identical and highly supported. These trees recovered the genus Penenirmus as monophyletic and identified several major clades, which tended to be associated with one major host group. However, cophylogenetic analysis revealed that host-switching was a prominent process in the diversification of this group. This host-switching generally occurred within single major biogeographic regions. We did, however, find one case in which it appears that a rare dispersal event by a woodpecker lineage from North America to Africa allowed its associated louse to colonize a woodpecker in Africa, even though the woodpecker lineage from North America never became established there.

Habitat Patch Size and Landscape Structure Influence, Although Weakly, the Parasite Richness of an Arboreal Folivorous-frugivorous Primate in Anthropogenic Landscapes

ContextAnthropogenic habitat disturbances that affect the ecology and behavior of parasites and hosts can either facilitate or compromise their interactions and modulate the parasite richness.ObjectivesWe assessed if the size of the habitat patch, the composition and configuration of the landscape (forest cover, patch density and mean distance to the nearest patch) and host group size influence the parasite richness of brown howler monkeys (Alouatta guariba clamitans) inhabiting forest fragments immersed in an anthropogenic matrix.MethodsWe collected fecal samples from 60 howler monkey groups inhabiting distinct forest fragments (one group/fragment) from January to July 2019. We used generalized linear models to assess the power of the independent variables in predicting parasite richness at the patch- and patch-landscape scales.ResultsWe found 10 parasite taxa (five basal eukaryotes, four nematodes and one platyhelminth), nine of which also infect humans or domestic animals. Overall parasite richness showed an inverse relationship with habitat patch size and forest cover, and a direct relationship with the mean distance to the nearest patch and group size. Patch-landscape metrics and host group size also influenced the infection with parasites with direct cycle and transmission via ingestion of the infective stage in the arboreal environment or with parasites with indirect cycle and transmission via ingestion of intermediate hosts. However, all significant models presented low weight.ConclusionsWe suggest that characteristics of parasite and host populations among other factors are more critical modulators of the relationship between howler monkeys and their parasites in anthropogenic landscapes.

Galaxy evolution across environments as probed by the ages, stellar metallicities, and [α /Fe] of central and satellite galaxies

ABSTRACT We explore how the star formation and metal enrichment histories of present-day galaxies have been affected by environment combining stellar population parameter estimates and group environment characterization for SDSS DR7. We compare stellar ages, stellar metallicities, and crucially, element abundance ratios $\rm [\alpha /Fe]$ of satellite and central galaxies, as a function of their stellar and host group halo mass, controlling for the current star formation rate and for the infall epoch. We confirm that below M* ∼ 1010.5 M⊙ satellites are older and slightly metal richer than equally massive central galaxies. In contrast, we do not detect any difference in their $\rm [\alpha /Fe]$: $\rm [\alpha /Fe]$ depends primarily on stellar mass and not on group hierarchy nor host halo mass. We also find that the differences in the median age and metallicity of satellites and centrals at stellar mass below $\rm 10^{10.5}\,M_\odot$ are largely due to the higher fraction of passive galaxies among satellites and as a function of halo mass. We argue that the observed trends at low masses reveal the action of satellite-specific environmental effects in a ‘delayed-then-rapid’ fashion. When accounting for the varying quiescent fraction, small residual excess in age, metallicity and $\rm [\alpha /Fe]$ emerge for satellites dominated by old stellar populations and residing in haloes more massive than 1014 M⊙, compared to equally massive central galaxies. This excess in age, metallicity, and $\rm [\alpha /Fe]$ pertain to ancient infallers, i.e. satellites that have accreted on to the current halo more than 5 Gyr ago. This result points to the action of environment in the early phases of star formation in galaxies located close to cosmic density peaks.