Host Specificity Research Articles

Discovery of adults of the gorgoderid trematode Cercaria duplicata with first morphological description, molecular identification and notes on host specificity

Rhopalocercous Cercaria duplicata von Baer, 1827 develops in an intermediate host, the unionid bivalve Anodonta anatina (L.), but its adult form has been unknown. We examined eight fish species occurring in the presence of a highly infested population of A. anatina in the Zesławice reservoir (S Poland). Gravid Phyllodistomum specimens were obtained from the ureters of ide, Leuciscus idus (L.) and common rudd, Scardinius erythrophthalmus (L.). One of the rudd specimens was doubly infected, a trematode was also found in the urinary bladder. In addition, a gravid Phyllodistomum specimen was found in the ureter of a tench Tinca tinca (L.), caught in Lake Ilmėdas (Lithuania). In order to clarify the phylogenetic position of larval and adult gorgoderids and to establish their life cycle, ITS2 and 28S rDNA sequences were analysed. The analysis showed that adult Phyllodistomum specimens located in the ureters are conspecific with C. duplicata. The trematode found in the urinary bladder of S. erythrophthalmus was P. folium (Olfers, 1816). It is suggested that adult stages of C. duplicata should be referred to as Phyllodistomum duplicatum n. comb. The intercaecal position of the uterus and the deeply-lobed ovary are the main features distinguishing it from other Phyllodistomum species. Host specificity and ecology are discussed.

A host-adapted auxotrophic gut symbiont induces mucosal immunodeficiency.

Harnessing the microbiome to benefit human health requires an initial step in determining the identity and function of causative microorganisms that affect specific host physiological functions. We show a functional screen of the bacterial microbiota from mice with low intestinal immunoglobulin A (IgA) levels; we identified a Gram-negative bacterium, proposed as Tomasiella immunophila, that induces and degrades IgA in the mouse intestine. Mice harboring T. immunophila are susceptible to infections and show poor mucosal repair. T. immunophila is auxotrophic for the bacterial cell wall amino sugar N-acetylmuramic acid. It delivers immunoglobulin-degrading proteases into outer membrane vesicles that preferentially degrade rodent antibodies with kappa but not lambda light chains. This work indicates a role for symbionts in immunodeficiency, which might be applicable to human disease.

Parasite Abundance‐Occupancy Relationships Across Biogeographic Regions: Joint Effects of Niche Breadth, Host Availability and Climate

ABSTRACTAimChanging biodiversity and environmental conditions may allow multi‐host pathogens to spread among host species and affect prevalence. There are several widely acknowledged theories about mechanisms that may influence variation in pathogen prevalence, including the controversially debated dilution effect and abundance‐occupancy relationship hypotheses. Here, we explore such abundance‐occupancy relationships for unique lineages of three vector‐borne avian blood parasite genera (the avian malaria parasite Plasmodium and the related haemosporidian parasites Parahaemoproteus and Leucocytozoon) across biogeographical regions.LocationNearctic‐Neotropical and Palearctic‐Afrotropical regions.MethodsWe compiled a cross‐continental dataset of 17,116 bird individuals surveyed from 46 bird assemblages across the Nearctic‐Neotropical and Palearctic‐Afrotropical regions and explored relationships between local parasite lineage prevalence and host assemblage metrics in a Bayesian random regression framework.ResultsMost lineages from these three genera infected ≥ 5 host species and exhibited clear phylogenetic or functional host specificity. Lineage prevalence from all three genera increased with host range, but also with higher degrees of specialisation to phylogenetically or functionally related host species. Local avian community features were also found to be important drivers of prevalence. For example, bird species richness was positively correlated with lineage prevalence for Plasmodium and Leucocytozoon, whereas higher relative abundances of the main host species were associated with lower prevalence for Plasmodium and Parahaemoproteus but higher prevalence for Leucocytozoon.ConclusionsOur results broadly support several of the leading hypotheses about mechanisms that influence pathogen prevalence, including the niche breadth hypothesis in that higher avian host species diversity and broader host range amplify prevalence through increasing ecological opportunities and the trade‐off hypotheses in that specialisation among subsets of available host species may increase prevalence. Furthermore, the three studied avian haemosporidian genera exhibited different abundance‐occupancy relationships across the major global climate gradients and in relation to host availability, emphasising that these relationships do not strictly follow common rules for vector‐borne parasites with different life histories.

Characterization and Genomic Analyses of dsDNA Vibriophage vB_VpaM_XM1, Representing a New Viral Family.

A novel vibriophage vB_VpaM_XM1 (XM1) was described in the present study. Morphological analysis revealed that phage XM1 had Myovirus morphology, with an oblate icosahedral head and a long contractile tail. The genome size of XM1 is 46,056 bp, with a G + C content of 42.51%, encoding 69 open reading frames (ORFs). Moreover, XM1 showed a narrow host range, only lysing Vibrio xuii LMG 21346 (T) JL2919, Vibrio parahaemolyticus 1.1997, and V. parahaemolyticus MCCC 1H00029 among the tested bacteria. One-step growth curves showed that XM1 has a 20-min latent period and a burst size of 398 plaque-forming units (PFU)/cell. In addition, XM1 exhibited broad pH, thermal, and salinity stability, as well as strong lytic activity, even at a multiplicity of infection (MOI) of 0.001. Multiple genome comparisons and phylogenetic analyses showed that phage XM1 is grouped in a clade with three other phages, including Vibrio phages Rostov 7, X29, and phi 2, and is distinct from all known viral families that have ratified by the standard genomic analysis of the International Committee on Taxonomy of Viruses (ICTV). Therefore, the above four phages might represent a new viral family, tentatively named Weiviridae. The broad physiological adaptability of phage XM1 and its high lytic activity and host specificity indicated that this novel phage is a good candidate for being used as a therapeutic bioagent against infections caused by certain V. parahaemolyticus strains.

Host Tropism and Structural Biology of ABC Toxin Complexes.

ABC toxin complexes are a class of protein toxin translocases comprised of a multimeric assembly of protein subunits. Each subunit displays a unique composition, contributing to the formation of a syringe-like nano-machine with natural cargo carrying, targeting, and translocation capabilities. Many of these toxins are insecticidal, drawing increasing interest in agriculture for use as biological pesticides. The A subunit (TcA) is the largest subunit of the complex and contains domains associated with membrane permeation and targeting. The B and C subunits, TcB and TcC, respectively, package into a cocoon-like structure that contains a toxic peptide and are coupled to TcA to form a continuous channel upon final assembly. In this review, we outline the current understanding and gaps in the knowledge pertaining to ABC toxins, highlighting seven published structures of TcAs and how these structures have led to a better understanding of the mechanism of host tropism and toxin translocation. We also highlight similarities and differences between homologues that contribute to variations in host specificity and conformational change. Lastly, we review the biotechnological potential of ABC toxins as both pesticides and cargo-carrying shuttles that enable the transport of peptides into cells.

Enumerating genotypic diversity and host specificity of Giardia in wild rodents around a New York watershed

Giardia is a genus of flagellated protozoans that parasitize the gastrointestinal tract of humans and wildlife worldwide. While G. duodenalis is well-studied due to its potential to cause outbreaks of diarrheal illness in humans, other Giardia species from wildlife have been largely understudied. This study examines the occurrence, host specificity, and genotypic diversity of Giardia in wild rodents living within the New York City water supply watershed. A novel nested PCR assay targeting the 18S ssu-rDNA gene is introduced, which captures nearly the entire gene for improved species-level determination versus existing molecular typing methods. Molecular characterization of 55 Giardia specimens reveals at least seven novel lineages. Phylogenetic analysis indicates a close relationship between the newly characterized Giardia lineages and rodent hosts, suggesting rodents as important reservoirs of Giardia and its close relatives. These findings provide insights into the diversity of Giardia species and their public health potential in localities with human-wildlife interaction and further emphasizes the need for continued efforts to improve the molecular tools used to study microbial eukaryotes, especially those with zoonotic potential.

N-linked protein glycosylation in Nanobdellati (formerly DPANN) archaea and their hosts.

Members of the kingdom Nanobdellati, previously known as DPANN archaea, are characterized by ultrasmall cell sizes and reduced genomes. They primarily thrive through ectosymbiotic interactions with specific hosts in diverse environments. Recent successful cultivations have emphasized the importance of adhesion to host cells for understanding the ecophysiology of Nanobdellati. Cell adhesion is often mediated by cell surface carbohydrates, and in archaea, this may be facilitated by the glycosylated S-layer protein that typically coats their cell surface. In this study, we conducted glycoproteomic analyses on two co-cultures of Nanobdellati with their host archaea, as well as on pure cultures of both host and non-host archaea. Nanobdellati exhibited various glycoproteins, including archaellins and hypothetical proteins, with glycans that were structurally distinct from those of their hosts. This indicated that Nanobdellati autonomously synthesize their glycans for protein modifications probably using host-derived substrates, despite the high energy cost. Glycan modifications on Nanobdellati proteins consistently occurred on asparagine residues within the N-X-S/T sequon, consistent with patterns observed across archaea, bacteria, and eukaryotes. In both host and non-host archaea, S-layer proteins were commonly modified with hexose, N-acetylhexosamine, and sulfonated deoxyhexose. However, the N-glycan structures of host archaea, characterized by distinct sugars such as deoxyhexose, nonulosonate sugar, and pentose at the nonreducing ends, were implicated in enabling Nanobdellati to differentiate between host and non-host cells. Interestingly, the specific sugar, xylose, was eliminated from the N-glycan in a host archaeon when co-cultured with Nanobdella. These findings enhance our understanding of the role of protein glycosylation in archaeal interactions.IMPORTANCENanobdellati archaea, formerly known as DPANN, are phylogenetically diverse, widely distributed, and obligately ectosymbiotic. The molecular mechanisms by which Nanobdellati recognize and adhere to their specific hosts remain largely unexplored. Protein glycosylation, a fundamental biological mechanism observed across all domains of life, is often crucial for various cell-cell interactions. This study provides the first insights into the glycoproteome of Nanobdellati and their host and non-host archaea. We discovered that Nanobdellati autonomously synthesize glycans for protein modifications, probably utilizing substrates derived from their hosts. Additionally, we identified distinctive glycosylation patterns that suggest mechanisms through which Nanobdellati differentiate between host and non-host cells. This research significantly advances our understanding of the molecular basis of microbial interactions in extreme environments.

Taxonogenomic analysis of the Xanthomonas translucens complex leads to the descriptions of Xanthomonas cerealis sp. nov. and Xanthomonas graminis sp. nov.

The pathovar-based taxonomy of the Xanthomonas translucens group is very confusing due to an overlap of plant host ranges and level of host specificity. Here, whole-genome sequence-based parameters (digital DNA–DNA hybridization and blast-based average nucleotide identity), phylogenomic, biochemical and phenotypical data were used to taxonomically analyse the 11 known pathovars of the X. translucens complex. This polyphasic approach taxonomically assigned the 11 pathovars of X. translucens complex into three distinct species, two of which are new: X. translucens, X. cerealis sp. nov. and X. graminis sp. nov. X. translucens consists of three pathovars: pv. translucens (=pv. hordei), pv. pistaciae strain A ICMP 16316PT and pv. undulosa (=pv. secalis). X. cerealis sp. nov. encompasses the pv. cerealis strain LMG 679PT and pv. pistaciae strain B ICMP 16317PT with genome similarity of 92.7% (dDDH) and 99.0% (ANIb) suggesting taxonomically similar genotypes. The other new species, X. graminis sp. nov., consists of the remaining five designated pathovars (pv. graminis, pv. arrhenatheri, pv. poae, pv. phleipratensis and pv. phlei) with highly variable dDDH and ANIb values ranging from 74.5 to 93.0% and from 96.7 to 99.2%, respectively, an indication of a very divergent taxonomic group. Only strains of pvs. phlei and phleipratensis showed the highest genomic similarities of 93.0% (dDDH) and 99.2% (ANIb), suggesting synonymic pathovars as both infect the same plant hosts. The dDDH and ANI data were corroborated by phylogenomics clustering. The fatty acid contents were similar but the type strain of X. graminis sp. nov. exhibited 20% less C15 : 0 iso and 40% more C17 : 0 iso fatty acids than the other species. Based on phenotypic, biochemical and whole-genome sequence data, we propose two new species, Xanthomonas cerealis sp. nov. and Xanthomonas graminis sp. nov. with type strains LMG 679T (=NCPPB 1944T) and LMG 726T (=NCPPB 2700T), respectively.

Design and performance of ELSA v2.0: an isochronal model for ice-sheet layer tracing

Abstract. We provide a detailed description of the ice-sheet layer age tracer Englacial Layer Simulation Architecture (ELSA) – a model that uses a straightforward method to simulate the englacial stratification of large ice sheets – as an alternative to Eulerian or Lagrangian tracer schemes. ELSA's vertical axis is time, and individual layers of accumulation are modeled explicitly and are isochronal. ELSA is not a standalone ice-sheet model but requires unidirectional coupling to another model providing ice physics and dynamics (the “host model”). Via ELSA's layer tracing, the host model’s output can be evaluated throughout the interior using ice core or radiostratigraphy data. We describe the stability and resolution dependence of this coupled modeling system using simulations of the last glacial cycle of the Greenland ice sheet using one specific host model. Key questions concern ELSA's design to maximize usability, which includes making it computationally efficient enough for ensemble runs, as well as exploring the requirements for offline forcing of ELSA with output from a range of existing ice-sheet models. ELSA is an open source and collaborative project, and this work provides the foundation for a well-documented, flexible, and easily adaptable model code to effectively force ELSA with (any) existing full ice-sheet model via a clear interface.

Engineering bacteriophages through deep mining of metagenomic motifs.

Bacteriophages can adapt to new hosts by altering sequence motifs through recombination or convergent evolution. Where such motifs exist and what fitness advantage they confer remains largely unknown. We report a new method, Metagenomic Sequence Informed Functional Scoring (Meta-SIFT), to discover sequence motifs in metagenomic datasets that can be used to engineer phage activity. Meta-SIFT uses experimental deep mutational scanning data to create sequence profiles to enable deep mining of metagenomes for functional motifs which are otherwise invisible to searches. We experimentally tested over 17,000 Meta-SIFT derived sequence motifs in the receptor-binding protein of the T7 phage. The screen revealed thousands of T7 variants with novel host specificity with functional motifs sourced from distant families. Position, substitution and location preferences dictated specificity across a panel of 20 hosts and conditions. To demonstrate therapeutic utility, we engineered active T7 variants against foodborne pathogen E. coli O121. Meta-SIFT is a powerful tool to unlock the functional potential encoded in phage metagenomes to engineer bacteriophages.

One must imagine Sisyphus happy: Integrative taxonomic characterization of 22 new Ceroptres species (Hymenoptera: Cynipidae: Ceroptresini)

We describe new species in the genus Ceroptres Hartig, 1840 (Hymenoptera: Cynipidae: Ceroptresini) represented by voucher material sequenced by Ward et al. (2024). We describe 22 new species, all authored by Nastasi, Smith, & Davis: C. anansii sp. nov., C. anzui sp. nov., C. bruti sp. nov., C. curupira sp. nov., C. daleki sp. nov., C. dandoi sp. nov., C. demerzelae sp. nov., C. iktomii sp. nov., C. jabbai sp. nov., C. jarethi sp. nov., C. lokii sp. nov., C. lupini sp. nov., C. mallowi sp. nov., C. promethei sp. nov., C. sandiegoae sp. nov., C. selinae sp. nov., C. soloi sp. nov., C. songae sp. nov., C. swiperi sp. nov., C. thrymi sp. nov., C. tikoloshei sp. nov., and C. zorroi sp. nov. After our taxonomic treatment, the genus Ceroptres includes 43 species, all but three of which are known from North America. Among our new species are two reared from cecidomyiid midge galls, an association previously recorded but without valid taxonomic association. We provide new records for two additional previously described species; we record C. ensiger (Walsh, 1864) from Pennsylvania and confirm characters for the male, and we record C. lanigerae Ashmead, 1885 from Texas. We also examined several putative species corresponding to either C. cornigera Melika & Buss, 2002 and/or C. frondosae Ashmead, 1896, which we regard as a species complex that requires elucidation in future studies. To enable further studies on Ceroptres, we provide an updated key to North American females. Overall, we find that species of Ceroptres are host specialists associated with a single host gall species or several galls that are phylogenetically or ecologically related. We suggest that there are many North American species of Ceroptres, possibly hundreds, still awaiting collection and characterization.

Dissecting negative effects of two root-associated bacteria on the growth of an invasive weed.

Plant-associated microorganisms can negatively influence plant growth, which makes them potential biocontrol agents for weeds. Two Gammaproteobacteria, Serratia plymuthica and Pseudomonas brassicacearum, isolated from roots of Jacobaea vulgaris, an invasive weed, negatively affect its root growth. We examined whether the effects of S. plymuthica and P. brassicacearum on J. vulgaris through root inoculation are concentration-dependent and investigated if these effects were mediated by metabolites in bacterial suspensions. We also tested whether the two bacteria negatively affected seed germination and seedling growth through volatile emissions. Lastly, we investigated the host specificity of these two bacteria on nine other plant species. Both bacteria significantly reduced J. vulgaris root growth after root inoculation, with S. plymuthica showing a concentration-dependent pattern in vitro. The cell-free supernatants of both bacteria did not affect J. vulgaris root growth. Both bacteria inhibited J. vulgaris seed germination and seedling growth via volatiles, displaying distinct volatile profiles. However, these negative effects were not specific to J. vulgaris. Both bacteria negatively affect J. vulgaris through root inoculation via the activity of bacterial cells, while also producing volatiles that hinder J. vulgaris germination and seedling growth. However, their negative effects extend to other plant species, limiting their potential for weed control.

Exploring symbiont gene expression in two echinoid-associated shrimp species under host separation

Symbiotic relationships are omnipresent and particularly diverse in the marine world. In the Western Indian Ocean, the sea urchin Echinometra mathaei associates with two obligate ectosymbiotic shrimp species, Tuleariocaris holthuisi and Arete indicus. These shrimps are known for their host-dependent nature. T. holthuisi, for example, exhibits severe host separation syndrome, showing signs of stress and rapid mortality when isolated. Specific host pigments called spinochromes seem essential for T. holthuisi survival. Our study employs a transcriptomic approach to assess the stress induced by host separation on these shrimps.Using paired-end Illumina HiSeq technology, we analyzed transcriptomes of both species under three conditions: (i) symbionts on their host (CC), (ii) isolated symbionts in seawater (IC), and (iii) isolated symbionts in spinochrome-enriched seawater (IC + S).Sequencing revealed a total of 217,832 assembled unigenes, with an N50 value of 2061 bp. Isolated T. holthuisi showed 16.5 % DEGs (IC/CC), reduced to 8.5 % with spinochromes (IC + S/CC), both compared to the control condition (CC). Further analyses of stress-related genes show that T. holthuisi expressed stress-related genes when isolated in comparison to the control (IC/CC). Notably, heat shock proteins (HSPs) were significantly up-regulated in isolated T. holthuisi, especially without spinochromes. In contrast, A. indicus displayed differential expression of diverse genes, suggesting an adaptive micro-regulation mechanism to cope with isolation stress.This study pioneers the use of NGS in exploring the transcriptomic responses of symbiotic shrimp species, shedding some light on the molecular impact of the host-separation syndrome and chemical dependencies.

Reciprocal transplant experiments demonstrate a dynamic coevolutionary relationship between parasitic mussel larvae and bitterling fishes

Abstract The coevolutionary dynamic of host–parasite associations varies from strictly local adaptations to diffuse guild coevolution. How innate and acquired immune responses modulate host resistance to parasitism and how host specificity and geographic scaling affect the efficacy of host response have consequences for range dynamics and biological invasions. Using reciprocal transplant experiments, we tested whether local or diffuse coevolution shapes host response to parasitism in the host–parasite association between bitterling fishes and larval stages (glochidia) of freshwater mussels from Europe and East Asia. We found that glochidia initially indiscriminately attached to all study host species, but immune responses elicited significant differences in host responses within 24 h of infection, which intensified during glochidial development. European bitterlings were more resistant to European glochidia and Asian bitterlings to Asian glochidia, with the strongest geographic bias in resistance in the Asian bitterling hosts. This finding suggests a strong effect of local adaptation but also indicates the non‐negligible role of coevolutionary hotspots. Low natural glochidia load on bitterling species overall hence arise from competent immune response rather than glochidia avoidance behaviour. Bitterling immune response is primarily innate and not acquired. Overall, our data demonstrate the complex outcome of parasite pressure on the evolution of host resistance, and important role of geographically structured coevolution in shaping host response.

Determining Gene Order Patterns in the Suillus and Boletales through Comparative Analysis of Their Mitogenomes.

Suillus is one of the most important genera of ectomycorrhizal fungi. As a model for studying host specificity, its molecular fragments and nuclear genome have been analyzed. However, its mitochondrial genome has not yet been reported. In this study, we assembled five mitogenomes of Suillus and analyzed and compared their basic characteristics. Owing to the large number of introns as well as intergenic regions, the mitogenomic lengths of species of Suillus were greater than those of other species of Boletales. We identified two main patterns of gene order arrangement in the members of the order Boletales. The Ka/Ks values of 15 protein-coding genes were <1 for the mitochondrial genes of 39 Boletales species, indicating their conserved evolution. Phylogenetic trees, reconstructed using the mitogenomes, indicated that the genus Suillus was monophyletic. Phylogenetic results based on the internal transcribed spacer region and mitogenome were used to confirm the distribution of Suillus placidus in China. The results showed that the mitogenome was superior in distinguishing species compared with a single molecular fragment. This is the first study to investigate the mitogenome of Suillus, enriching the mitogenome information and providing basic data for the phylogeny, resource conservation, and genetic diversity of this genus.

Detection, isolation and characterization of phage-host complexes using BONCAT and click chemistry.

Phages are viruses that infect prokaryotes and can shape microbial communities by lysis, thus offering applications in various fields. However, challenges exist in sampling, isolation and accurate prediction of the host specificity of phages as well as in the identification of newly replicated virions in response to environmental challenges. A new workflow using biorthogonal non-canonical amino acid tagging (BONCAT) and click chemistry (CC) allowed the combined analysis of phages and their hosts, the identification of newly replicated virions, and the specific tagging of phages with biotin for affinity chromatography. Replication of phage λ in Escherichia coli was selected as a model for workflow development. Specific labeling of phage λ proteins with the non-canonical amino acid 4-azido-L-homoalanine (AHA) during phage development in E. coli was confirmed by LC-MS/MS. Subsequent tagging of AHA with fluorescent dyes via CC allowed the visualization of phages adsorbed to the cell surface by fluorescence microscopy. Flow cytometry enabled the automated detection of these fluorescent phage-host complexes. Alternatively, AHA-labeled phages were tagged with biotin for purification by affinity chromatography. Despite biotinylation the tagged phages could be purified and were infectious after purification. Applying this approach to environmental samples would enable host screening without cultivation. A flexible and powerful workflow for the detection and enrichment of phages and their hosts in pure cultures has been established. The developed method lays the groundwork for future workflows that could enable the isolation of phage-host complexes from diverse complex microbial communities using fluorescence-activated cell sorting or biotin purification. The ability to expand and customize the workflow through the growing range of compounds for CC offers the potential to develop a versatile toolbox in phage research. This work provides a starting point for these further studies by providing a comprehensive standard operating procedure.

Bacterial allelopathy: an approach for biological control of weeds.

Weed infestation is one of the most damaging biotic factors to limit crop production by competing with the crop for space, water, and nutrients. Different conventional approaches are being used to cope with weed infestation, including labor intensive manual removal and the use of soil-degrading, crop-damaging, and environment-deteriorating chemical herbicides. The use of chemicals for weed control has increased 2-fold after the green revolution and their non-judicious use is posing serious threats to mankind, animals, and biodiversity. The detrimental effects of these approaches have shifted the researchers' attention from the last two decades towards alternate, sustainable, and eco-friendly approaches to cope with weed infestation. The recent approaches of weed control, including plant and microbial allelopathy have gained popularity during last decade. Farmers still use conventional methods, but the majority of farmers are very passionate about organic agriculture and describe it as a slogan in the developed world. The effectiveness of these approaches lies in host specificity by selective bacteria and differential response towards weeds and crops. Moreover, the crop growth promoting effect of microorganisms (allelopathic bacteria) possessing various growth promoting traits, that is, mineral solubilization, phytohormone production, and beneficial enzymatic activity, provide additional benefits. The significance of this review lies in the provision of a comprehensive comparison of the conventional approaches along with their potential limitations with advanced/biological weed control approaches in sustainable production. In addition, the knowledge imparted about weed control will contribute to a better understanding of biological control methods.

Niche partitioning and host specialisation in fish-parasitising isopods: Trait-dependent patterns from three ecosystems on the east coast of India.

Due to their large size and obligate nature, Cymothoid isopods inflict a high degree of tissue damage to fish. Still, they are understudied at an ecosystem level despite their global presence and ecological role. In this work, we collected fish host-isopod parasite data, along with their life history and ecological traits, from the northern part of the east coast of India and investigated patterns in host specialisation and preference of isopod parasites using a trait-based network perspective. We observed that the region of attachment of the parasite (buccal cavity, branchial cavity, and skin) and host fish ecology (schooling behaviour and habitat characteristics) influenced host specialisation and preference. We found that branchial cavity-attaching parasites preferred schooling, pelagic fishes, whereas buccal cavity-attaching parasites preferred mostly non-schooling, demersal fishes. Skin-attaching parasites were found to be generalists and had no preference based on our examined host traits.

Cryptosporidium spp. in German wildlife: Detection, regional occurrence and diversity in wild boar, roe, red and fallow deer

Cryptosporidium is a cause of diarrheal infections responsible for a loss of human and animal welfare worldwide. The impact of the parasite is underestimated and the reported sources of infection are diverse, as it occurs in a wide variety of hosts. Wildlife has been reported as a notifiable source, but few studies are available on its occurrence in European wild boar and cervid species. To determine the occurrence of Cryptosporidium in game in Brandenburg, Germany, a molecular survey was conducted during the 2017 to 2020 hunting seasons. A total of 562 fecal samples from wild boar (Sus scrofa, n = 262), roe deer (Capreolus capreolus, n = 174), red deer (Cervus elaphus, n = 62), fallow deer (Dama dama, n = 51) and 13 samples of unspecified species were analyzed for both 18S ribosomal RNA (18S rRNA) and Cryptosporidium oocyst wall protein (COWP) gene sequence regions. PCR results showed that 21.2 % of the samples (n = 119/562) were positive for at least one target gene (18S rRNA: n = 114; COWP: n = 14), but differences in Cryptosporidium occurrence were observed within species and hunting seasons, with variations ranging from 1.8 % to 41.7 % (roe deer), respectively. Analysis of Sanger sequences of the 18S rRNA and COWP PCR products indicated that the C. sp. deer genotype was predominant in deer (roe deer: 86.7 %, red deer: 66.7 %, fallow deer: 58.8 %), while C. suis and C. scrofarum were mainly detected in wild boar (88.5 %). The human pathogenic species C. parvum was detected in only 1.2 % (n = 7) of the samples analyzed, but without a clear indication of a specific wild animal host. The highest Cryptosporidium diversity was found in wild boar and roe deer with five and four different species, respectively. Comparison of the 18S rRNA sequences with the designated reference revealed minor variations at several nucleotide positions in some isolates, possibly indicating evolutionary adaptations and the development of new subtypes. In conclusion, wildlife represents a reservoir for a diverse spectrum of Cryptosporidium species and may thus contribute to their environmental spread and the transmission to humans.

Calliobothrium Narsisae n. sp. (Tetraphyllidea: Calliobothriidae) from the Triakid Shark Mustelus mosis Hemprich and Ehrenberg from the Persian Gulf, with a Note on Its Specific Proglottisation Process and a Key to the Species of the Genus.

The members of the tetraphyllidean genus Calliobothrium exhibit a high degree of host specificity in the shark genus Mustelus. In the Indian Ocean, where M. mosis occurs dominantly, there is no information on Calliobothrium. The purpose of this study was the evaluation of the Calliobothrium species in M. mosis in the Persian Gulf, northwestern Indian Ocean. Nine specimens of Mustelus mosis were caught from the Persian Gulf. The tapeworms isolated were stained, measured, and the line drawings were made. Calliobothrium narsisae n. sp. is described and differs from C. creeveyae in the intact, rather than the three-lobed, posterior bothridial margins, from C. tylotocephalum in possessing three, rather than one, suckers per bothridial muscular pad, from C. nodosum in possessing the elongated, rather than robust and thorn-like, hooks, from C. shirozame in a maximum number of four, rather than three, dorsal and four, rather than three, ventral laciniations along the strobila, and from its other congeners in possessing three, rather than two, dorsal and three, rather than two, ventral laciniations in the anteriormost immature proglottids. A key to the species of the genus is presented and the proglottisation process, by the germinative zone placed in the terminal part of the worm at least in some stages of growth to maturity, is discussed. The description of C. narsisae n. sp., which brings the total number of valid species of Calliobothrium to 10, also indicates that the germinative zone is not always at the anterior to strobila and in this new species it is placed in the terminal part of the worm at least in some stages of growth to maturity.