Biology subjects

Jones, C.

Publications and source records attributed to Jones, C..

At least 73 records · Page 4Linked to original sources

bioRxiv2021

Comparison of neuromuscular junction dynamics following ischemic and aged skeletal muscle

Both aging and neuromuscular diseases lead to significant changes in the morphology and functionality of the neuromuscular synapse. Skeletal muscles display a remarkable regenerative capacity, however, are still susceptible to diseases of aging and peripheral nerve perturbations. In this study, we assessed how neuromuscular synapses differ in aged and injured skeletal muscle using an improved neuromuscular junction (NMJ) staining and imaging method. We found that both aged and ischemic skeletal muscle display Wallerian degeneration of the presynaptic motor axons and fragmentation of postsynaptic acetylcholine receptors (AChRs). Quantifiable measurements of various metrics of the NMJs provide a more concrete idea of the dynamics that are occurring in the muscle microenvironment. We questioned whether neuronal degradation precedes myofiber atrophy or vice versa. Previously, it was shown that a cellular crosstalk exists among the motor neurons, myofibers, vasculature, and mitochondria within the muscle microdomain. It is apparent that lack of blood flow to motor neurons in ischemic skeletal muscle disrupts the structure of NMJs, however it is unclear if the aging condition experiences similar dynamics. We demonstrated that both aged and ischemic skeletal muscle demonstrate similar patterns of degeneration, characterized by a smaller percentage overlap of presynaptic and postsynaptic sides, greater fragmentation of AChRs, and a smaller area of AChR clusters. Together, these results reveal high resolution, precise parallels between the aged and ischemic NMJs. Impact StatementThe goal of this study was to assess changes in presynaptic motor neurons and postsynaptic acetylcholine receptors following an ischemic injury model and compare this with an aging model. This was accomplished by characterizing key components of NMJ morphology, including overlap and size of the receptors. There is currently limited research investigating the cellular communication between skeletal muscle fibers and motor neurons. Additionally, there is limited work comparing neuromuscular remodeling in aged and young models. With the substantial prevalence of neuromuscular disorders, especially in the aging population, it is essential to understand nerve-muscle interactions in order to promote increased mobility and improved quality of life in both injury and aging models.

neuroscience↗

bioRxiv2021

Loss of the H4 lysine methyltransferase KMT5B drives tumorigenic phenotypes by depleting H3K27me3 at loci otherwise retained in H3K27M mutant DIPG cells

DIPG are characterised by histone H3K27M mutations, resulting in global loss of the repressive mark H3K27me3, although certain key loci are retained. We recently identified subclonal loss-of-function mutations in the H4 lysine methyltransferase KMT5B to be associated with enhanced invasion/migration, but the mechanism by which this occurred was unclear. Here we use integrated ChIP-seq, ATAC-seq and RNA-seq on patient-derived, subclonal and CRISPR-Cas9-KD DIPG cells to show that loss of KMT5B/C causes depletion of these retained H3K27me3 loci via changes in chromatin accessibility, causing a raft of transcriptional changes which promote tumorigenesis. De-repression occurred at bivalent loci marked by H3K4me3, driving increased transcriptional heterogeneity and elevated gene expression associated with increased invasion, abrogated DNA repair and mesenchymal transition, along with a markedly altered secretome. These data suggest a previously unrecognised trans-histone (H4/H3) interaction in DIPG cells with a potentially profound effect on their diffusely infiltrating phenotype.

cancer biology↗

bioRxiv2021

Quantification of spatial subclonal interactions enhancing the invasive phenotype of paediatric glioma

Intra-tumour heterogeneity is an intrinsic property of all cancers. In some cases, such variation can be maintained by interactions between tumour subclones with distinct molecular and phenotypic characteristics. In paediatric gliomas, interactions can take the form of enhanced invasive phenotype, a hallmark of these malignancies. However, subclonal interactions are hard to quantify and difficult to distinguish from spatial confounding factors and experimental bias. Here we combine spatial computational modelling of cellular interactions and invasion, with co-evolution experiments of clonally disassembled primary glioma lines derived at autopsy. We design a Bayesian inference framework to quantify spatial subclonal interactions between molecular and phenotypically distinct lineages with different patterns of invasion. We show how this approach could discriminate genuine subclonal interactions where one clone enhanced the invasive phenotype of another, from apparent interactions that were only due to the complex dynamics of subclones growing in space. This study provides a new approach for the identification and quantification of spatial subclonal interactions in cancer.

cancer biology↗

bioRxiv2021

Novel Hendra virus variant detected by sentinel surveillance of Australian horses.

A novel Hendra virus (HeV) variant, not detected by routine testing, was identified and isolated from a Queensland horse that suffered acute, fatal disease consistent with HeV infection. Whole genome sequencing and phylogenetic analysis demonstrated the variant to have ~83% nucleotide identity to the prototype HeV strain. An updated RT-qPCR assay was designed for routine HeV surveillance. In silico and in vitro comparison of the receptor-binding protein with prototypic HeV showed that the human monoclonal antibody m102.4 used for post-exposure prophylaxis, as well as the current equine vaccine, should be effective against this variant. Genetic similarity of this virus to sequences detected from grey-headed flying-foxes suggests the variant circulates at-least in this species. Studies determining infection kinetics, pathogenicity, reservoir-species associations, viral-host co-evolution and spillover dynamics for this virus are urgently needed. Surveillance and biosecurity practices should be updated to appreciate HeV spillover risk across all regions frequented by flying foxes.

molecular biology↗

bioRxiv2021

Single Cell Transcriptomics Reveals Cell Type Specific Diversification in Human Heart Failure

Heart failure represents a major cause of morbidity and mortality worldwide. Single cell transcriptomics have revolutionized our understanding of cell composition and associated gene expression across human tissues. Through integrated analysis of single cell and single nucleus RNA sequencing data generated from 45 individuals, we define the cell composition of the healthy and failing human heart. We identify cell specific transcriptional signatures of heart failure and reveal the emergence of disease associated cell states. Intriguingly, cardiomyocytes converge towards a common disease associated cell state, while fibroblasts and myeloid cells undergo dramatic diversification. Endothelial cells and pericytes display global transcriptional shifts without changes in cell complexity. Collectively, our findings provide a comprehensive analysis of the cellular and transcriptomic landscape of human heart failure, identify cell type specific transcriptional programs and states associated with disease, and establish a valuable resource for the investigation of human heart failure.

genomics↗

bioRxiv2021

Intrinsic and extrinsic regulation of human fetal bone marrow haematopoiesis and perturbations in Down syndrome

Throughout postnatal life, haematopoiesis in the bone marrow (BM) maintains blood and immune cell production. Haematopoiesis first emerges in human BM at 12 post conception weeks while fetal liver (FL) haematopoiesis is still expanding. Yet, almost nothing is known about how fetal BM evolves to meet the highly specialised needs of the fetus and newborn infant. Here, we detail the development of fetal BM including stroma using single cell RNA-sequencing. We find that the full blood and immune cell repertoire is established in fetal BM in a short time window of 6-7 weeks early in the second trimester. Fetal BM promotes rapid and extensive diversification of myeloid cells, with granulocytes, eosinophils and dendritic cell (DC) subsets emerging for the first time. B-lymphocyte expansion occurs, in contrast with erythroid predominance in FL at the same gestational age. We identify transcriptional and functional differences that underlie tissue-specific identity and cellular diversification in fetal BM and FL. Finally, we reveal selective disruption of B-lymphocyte, erythroid and myeloid development due to cell intrinsic differentiation bias as well as extrinsic regulation through an altered microenvironment in the fetal BM from constitutional chromosome anomaly Down syndrome during this crucial developmental time window.

developmental biology↗

bioRxiv2021

Changes in splicing and neuromodulatory gene expression programs in sensory neurons with pheromone signaling and social experience

Social experience and pheromone signaling in olfactory neurons affect neuronal responses and male courtship behaviors in Drosophila. We previously showed that social experience and pheromone signaling modulate chromatin around behavioral switch gene fruitless, which encodes a transcription factor necessary and sufficient for male behaviors. Fruitless drives social experience dependent modulation of courtship behaviors and pheromone responses in sensory neurons, however, the molecular mechanisms underlying this neuromodulation remain less clear. To identify the molecular mechanisms driving social experience-dependent neuromodulation, we performed RNA-seq from antennal samples of mutants in pheromone receptors and fruitless, as well as grouped or isolated wild-type males. We found that loss of pheromone detection differentially alters the levels of fruitless exons suggesting changes in splicing patterns. In addition, many Fruitless target neuromodulatory genes, such as neurotransmitter receptors, ion channels, ion and membrane transporters, and odorant binding proteins are differentially regulated by social context and pheromone signaling. Recent studies showed that social experience and juvenile hormone signaling coregulate fru chromatin to modify pheromone responses in olfactory neurons. Interestingly, genes involved in juvenile hormone metabolism are also misregulated in different social contexts and mutant backgrounds. Our results suggest that modulation of neuronal activity and behaviors in response to social experience and pheromone signaling likely arise due to large-scale changes in transcriptional programs for neuromodulators downstream of behavioral switch gene function.

neuroscience↗

bioRxiv2021

The influence of sex, hormone status, and growth rate on dietary isotope fractionation: a case study with laboratory rats

Stable isotope analysis is increasingly used to discern ecological differences within and among species, especially those difficult to observe. In applied ecological studies, variations in stable isotope composition are often attributed to foraging behavior or trophic ecology rather than fractionation during metabolic processes. One physiological difference among individuals is gonadal hormone levels, which affects food intake, metabolism, and locomotor activity. However, it is unclear how these effects- isolated from ecology- affect metabolic dynamics and expression in stable isotope analysis. Here, we test the linkage between gonadal hormones and isotopic heterogeneity among individuals with captive rats. We found that sex and removal of gonadal hormones are factors either individually or interactive for {delta}15N and {delta}13C values in serum and blood as well as {delta}15N values of muscle and liver. Furthermore, the degree of fractionation in these tissues is related to growth rate. Gonadectomization also affected isotopic composition for liver {delta}13C values and kidney {delta}15N values, but fat {delta}13C values were affected only by sex. The pattern of differentiation between groups was most different for kidney {delta}15N and {delta}13C values, which also had the largest isotopic variability among groups. Overall, isotopic variation within one tissue for the four groups demonstrated up to 1{per thousand} difference in {delta}13C and {delta}15N values suggesting that sex based within population variations should into consideration these potential physiological effects. What is already knownThere are isotopic differences between diet and various consumer tissues with variability among individuals, which is often characterized based on captive feeding studies. Effects of protein quality and quantity, variable growth rate based on ontogeny, and differences between sexes have been tested thus far in experiments. Furthermore, it is known that gonadal hormones affect energy regulation with difference in weight gain, which suggest differences in extent and rate of biochemical processes. What this study addsThis study demonstrates effects of gonadal hormone status with metabolic biochemistry by using stable isotopes of carbon and nitrogen as dietary tracers. We find that gonadal hormone status accounts for some isotopic heterogeneity among individuals, which should be considered when interpreting stable isotope data from wild specimens. Rather than attributing isotopic differences to ecological factors, such as foraging preference, there may be underlying physiological processes that differentiate groups based on ontogeny and sex.

ecology↗

bioRxiv2021

Genetic Susceptibility to Enteric Fever in Experimentally Challenged Human Volunteers

BackgroundInfection with Salmonella enterica serovars Typhi and Paratyphi A cause an estimated 14 million cases of enteric fever annually. Here the controlled nature of challenge studies is exploited to identify genetic variants associated with enteric fever susceptibility. MethodsHuman challenge participants were genotyped by Illumina OmniExpress-24 BeadChip array (n=176) and/or transcriptionally profiled by RNA-sequencing (n=178). ResultsTwo SNPs within CAPN14 and MIATNB were identified with p<10-5 for association with development of symptoms or bacteraemia following oral S. Typhi or S. Paratyphi A challenge. Imputation of classical human leukocyte antigen (HLA) types from genomic and transcriptomic data identified HLA-B*27:05, previously associated with non-typhoidal Salmonella-induced reactive arthritis, as the HLA type most strongly associated with enteric fever susceptibility (p=0.012). Genes related to the unfolded protein response and heat shock were over-represented in HLA-B*27:05+ participants following challenge (p=0.01). Furthermore, intracellular replication of S. Typhi is higher in C1R cells transfected with HLA-B*27:05 (p=0.02). ConclusionThese data suggest that activation of the unfolded protein response by HLA-B*27:05 misfolding may create an intracellular environment conducive to S. Typhi replication, increasing susceptibility to enteric fever.

genetics↗

bioRxiv2020

A Kernel-Based Change Detection Method to Map Shifts in Phytoplankton Communities Measured by Flow Cytometry

O_LIAutomated, ship-board flow cytometers provide high-resolution maps of phytoplankton composition over large swaths of the worlds oceans. They therefore pave the way for understanding how environmental conditions shape community structure. Identification of community changes along a cruise transect commonly segments the data into distinct regions. However, existing segmentation methods are generally not applicable to flow cytometry data, as this data is recorded as "point cloud" data, with hundreds or thousands of particles measured during each time interval. Moreover, nonparametric segmentation methods that do not rely on prior knowledge of the number of species, are desirable to map community shifts. C_LIO_LIWe present CytoSegmenter, a kernel-based change-point estimation method for segmenting point cloud data that does not rely on parametric assumptions on the data distributions. Our method relies on a Hilbertian embedding of point clouds that allows us to work with point cloud data similarly to vectorial data. The change-point locations can be found using an efficient dynamic programming algorithm. The method can be used to automatically segment long series of underway flow cytometry data. C_LIO_LIThrough an analysis of 12 cruises, we demonstrate that CytoSegmenter allows us to locate abrupt changes in phytoplankton community structure. We show that the changes in community structure generally coincide with changes in the temperature and salinity of the ocean. We also illustrate how the main parameter of CytoSegmenter can be easily calibrated using limited auxiliary annotated data. C_LIO_LICytoSegmenter is publicly available and implemented in the programming language Python. The method is generally applicable for segmenting series of point cloud data from any domain. Moreover, it readily scales to thousands of point clouds, each containing thousands of points. In the context of underway flow cytometry data, it does not require prior clustering of particles to define taxa labels, eliminating a potential source of error. This represents an important advance in automating the analysis of large datasets now emerging in biological oceanography and other fields. It also allows for the approach to potentially be applied during research cruises. C_LI

ecology↗

bioRxiv2020

Poised cell circuits in human skin are activated in disease

The human skin confers biophysical and immunological protection through a complex cellular network that is established early in development. We profiled ~500,000 single cells using RNA-sequencing from healthy adult and developing skin, and skin from patients with atopic dermatitis and psoriasis. Our findings reveal a predominance of innate lymphoid cells and macrophages in developing skin in contrast to T cells and migratory dendritic cells in adult skin. We demonstrate dual keratinocyte differentiation trajectories and activated cellular circuits comprising vascular endothelial cells mediating immune cell trafficking, disease-specific clonally expanded IL13/IL22 and IL17A/F-expressing lymphocytes, epidermal IL23-expressing dendritic cells and inflammatory keratinocytes in disease. Our findings provide key insights into the dynamic cellular landscape of human skin in health and disease. One Sentence SummarySingle cell atlas of human skin reveals cell circuits which are quantitatively and qualitatively reconfigured in inflammatory skin disease.

immunology↗

bioRxiv2020

ASPP2/PP1 complexes maintain the integrity of pseudostratified epithelia undergoing remodelling during morphogenesis

During development, pseudostratified epithelia undergo large scale morphogenetic events associated with increased mechanical stress. The molecular mechanisms that maintain tissue integrity in this context are poorly understood. Using a variety of genetic and imaging approaches, we uncover that the ASPP2/PP1 complex ensures proper epiblast and proamniotic cavity architecture via a mechanism that specifically prevents the most apical daughter cells from delaminating apically following cell division events. The ASPP2/PP1 complex achieves this by maintaining the integrity and organisation of the F-actin cytoskeleton at the apical surface of dividing cells. ASPP2/PP1 is also essential during gastrulation in the primitive streak, in somites and in the head fold region, suggesting that this complex is required across a wide range of pseudostratified epithelia during morphogenetic events that are accompanied by intense tissue remodelling and high cell proliferation. Finally, our study also suggests that the interaction between ASPP2 and PP1 is essential to the tumour suppressor function of ASPP2 which may be particularly relevant in the context of tissues that are subject to increased mechanical stress.

developmental biology↗

bioRxiv2020

In vitro assessment of the virucidal activity of four mouthwashes containing Cetylpyridinium Chloride, ethanol, zinc and a mix of enzyme and proteins against a human coronavirus

Backgroundsaliva is established to contain high counts SARS-CoV-2 virus and contact with saliva droplets, contaminated surfaces or airborne particles are sources of viral transmission. The generation of infective aerosols during clinical procedures is of particular concern. Therefore, a fuller understanding of the potential of mouthwash to reduce viral counts and modulate the risk of transmission in medical professional and public context is an important research topic. Methodwe determined the virucidal activity of four anti-bacterial mouthwashes against a surrogate for SARS-CoV-2, Human CoV-SARS 229E, using a standard ASTM suspension test, with dilution and contact times applicable to recommended mouthwash use. Resultsthe mouthwash formulated with 0.07% Cetylpyridinium Chloride exhibited virucidal effects providing a [≥]3.0 log reduction HCoV-229E viral count. Mouthwashes containing 15.7% ethanol, 0.2% zinc sulphate heptahydrate and a mix of enzymes and proteins did not demonstrate substantive virucidal activity in this test. Conclusionmouthwash containing 0.07% Cetylpyridinium Chloride warrants further laboratory and clinical assessment to determine their potential benefit in reducing the risk of SARS-CoV-2. HighlightsSARS-CoV-2 can be transmitted through contact with infective saliva. Studies are needed to understand if mouthwash can lower SARS-CoV-2 transmission risk. 0.07% Cetylpyridinium Chloride (CPC) mouthwash exhibited virucidal effects against HCoV-SARS 229E. Further studies on potential of 0.07% CPC mouthwash against SARS-CoV-2 are warranted.

microbiology↗

bioRxiv2020

Deep conservation of ribosome stall sites across RNA processing genes

The rate of translation can vary considerably depending on the mRNA template. During the elongation phase the ribosome can transiently pause or permanently stall. A pause can provide the nascent protein with the required time to fold or be transported, while stalling can serve as quality control and trigger degradation of aberrant mRNA and peptide. Ribosome profiling has allowed for the genome-wide detection of such pause and stall sites, but due to library-specific biases, these predictions are often unreliable. Here, we address this by taking advantage of the deep conservation of the protein synthesis machinery, hypothesizing that similar conservation could exist for functionally important positions of ribosome slowdown - here collectively called stall sites. We analyze multiple ribosome profiling datasets from a phylogenetically diverse group of eukaryotes: yeast, fruit fly, zebrafish, mouse, and human and identify conserved stall sites. We find thousands of stall sites across multiple species, with proline, glycine, and negatively charged amino acids being the main facilitators of stalling. Many of the sites are found in RNA processing genes, suggesting that stalling might have a conserved regulatory effect on RNA metabolism. In summary, our results provide a rich resource for the study of conserved stalling and indicate possible roles of stalling in gene regulation.

genomics↗

bioRxiv2020

A subset of pediatric thalamic gliomas share a distinct DNA methylation profile, H3K27me3 loss and frequent alteration of EGFR

BackgroundMalignant astrocytic gliomas in children show a remarkable biological and clinical diversity. Small in-frame insertions or missense mutations in the EGFR gene have recently been identified in a distinct subset of pediatric bithalamic gliomas with a unique DNA methylation pattern. MethodsHere, we investigated an epigenetically homogeneous cohort of malignant gliomas (n=58) distinct from other subtypes and enriched for pediatric cases and thalamic location, in order to elucidate the overlap with this recently identified subtype of pediatric bithalamic gliomas. ResultsEGFR gene amplification was detected in 16/58 (27%) tumors, and missense mutations or small in-frame insertions in EGFR were found in 20/30 tumors with available sequencing data (67%; five of them co-occurring with EGFR amplification). Additionally, eight of the 30 tumors (27%) harbored an H3.1 or H3.3 K27M mutation (six of them with a concomitant EGFR alteration). All tumors tested showed loss of H3K27me3 staining, with evidence of EZHIP overexpression in the H3 wildtype cases. Although some tumors indeed showed a bithalamic growth pattern, a significant proportion of tumors occurred in the unilateral thalamus or in other (predominantly midline) locations. ConclusionsOur findings present a distinct molecular class of pediatric malignant gliomas largely overlapping with the recently reported bithalamic gliomas characterized by EGFR alteration, but additionally showing a broader spectrum of EGFR alterations and tumor localization. Global H3K27me3 loss in this group appears to be mediated by either H3 K27 mutation or EZHIP overexpression. EGFR inhibition may represent a potential therapeutic strategy in these highly aggressive gliomas. Key pointsO_LIThis study confirms a distinct new subset of pediatric diffuse midline glioma with H3K27me3 loss, with or without H3 K27 mutation C_LIO_LIThe poor outcome of these tumors is in line with the broader family of pediatric diffuse midline gliomas with H3 K27 mutation or EZHIP overexpression C_LIO_LIFrequent EGFR alterations in these tumors may represent a therapeutic target in this subset C_LI Importance of the StudyMalignant astrocytic gliomas in children show a remarkable biological and clinical diversity. Here, we highlight a distinct molecular class of pediatric malignant gliomas characterized by EGFR alteration and global H3K27me3 loss that appears to be mediated by either H3 K27 mutation or EZHIP overexpression. EGFR inhibition may represent a potential therapeutic strategy in these highly aggressive gliomas.

cancer biology↗

bioRxiv2020

Transmission and control strategies for porcine reproductive and respiratory syndrome virus

Many aspects of the porcine reproductive and respiratory syndrome virus (PRRSV) between-farm transmission dynamics have been investigated, but uncertainty remains about the significance of farm type and different transmission routes on PRRSV spread. We developed a stochastic epidemiological model calibrated on weekly PRRSV outbreaks accounting for the population dynamics in different pig production phases, breeding herds, gilt development units, nurseries, and finisher farms, of three hog producer companies. Our model accounted for indirect contacts by the close distance between farms (local transmission), between-farm animal movements (pig flow), and reinfection of sow farms (re-break). The fitted model was used to examine the effectiveness of vaccination strategies and complementary interventions such as enhanced PRRSV detection and vaccination delays and forecast the spatial distribution of PRRSV outbreak. The results of our analysis indicated that for sow farms, 59% of the simulated infections were related to local transmission (e.g. airborne, feed deliveries, shared equipment) whereas 36% and 5% were related to animal movements and re-break, respectively. For nursery farms, 80% of infections were related to animal movements and 20% to local transmission; while at finisher farms it was split between local transmission and animal movements. Assuming that the current vaccines are 1% effective in mitigating between-farm PRRSV transmission, weaned pigs vaccination would reduce the incidence of PRRSV outbreaks by 2%, indeed under any scenario vaccination alone was insufficient for completely controlling PRRSV spread. Our results also showed that intensifying PRRSV detection and/or vaccination pigs at placement increased the effectiveness of all simulated vaccination strategies. Our model reproduced the incidence and PRRSV spatial distribution; therefore, this model could also be used to map current and future farms at-risk. Finally, this model could be a useful tool for veterinarians, allowing them to identify the effect of transmission routes and different vaccination interventions to control PRRSV spread.

ecology↗

bioRxiv2020

Kill and cure: genomic phylogeny and bioactivity of a diverse collection of Burkholderia gladioli bacteria capable of pathogenic and beneficial lifestyles

Burkholderia gladioli is one of few bacteria with a broad ecology spanning disease in humans, animals, and plants, and encompassing beneficial interactions with multiple eukaryotic hosts. It is a plant pathogen, a bongkrekic acid toxin producing food-poisoning agent, and a lung pathogen in people with cystic fibrosis (CF). Contrasting beneficial traits include antifungal production exploited by insects to protect their eggs, plant protective abilities and antibiotic biosynthesis. We explored the ecological diversity and specialized metabolite biosynthesis of 206 B. gladioli strains, phylogenomically defining 5 evolutionary clades. Historical disease pathovars (pv) B. gladioli pv. allicola and B. gladioli pv. cocovenenans were phylogenetically distinct, while B. gladioli pv. gladioli and B. gladioli pv. agaricicola were indistinguishable. Soft-rot disease and CF infection pathogenicity traits were conserved across all pathovars. Biosynthetic gene clusters for toxoflavin, caryoynencin and enacyloxin were dispersed across B. gladioli, but bongkrekic acid and gladiolin production were clade specific. Strikingly, 13% of CF-infection strains characterised (n=194) were bongkrekic acid toxin positive, uniquely linking this food-poisoning risk factor to chronic lung disease. Toxin production was suppressed by exposing strains to the antibiotic trimethoprim, providing a potential therapeutic strategy to minimise poisoning risk in CF.

microbiology↗

bioRxiv2020

Infestation dynamics between parasitic Antarctic fish leeches (Piscicolidae) and their crocodile icefish hosts (Channichthyidae)

An understanding of host-parasite interactions represents an important, but often overlooked, axis for predicting how marine biodiversity may be impacted by continued environmental change over the next century. For host and parasite communities in the Southern Ocean, investigations of many major groups of parasites have largely been limited to taxonomic and phylogenetic studies, creating an urgent need for the collection of baseline ecological data if we are to detect changes in host-parasite interactions in the future. Here, we survey three species of Crocodile icefish (Notothenioidei: Channichthyidae) collected from two island archipelagos in Antarcticas South Scotia Arc region for evidence of leech infestations. Specifically, we report on infestation prevalence and intensity of three leech species (Trulliobdella bacilliformis, Trulliobdella capitis, and Nototheniobdella sawyeri) on the host fish species Chaenocephalus aceratus, Champsocephalus gunnari, and Chionodraco rastrospinosus. Additionally, we characterize spatial patterns of relative abundances of each leech species across the Elephant and South Orkney Islands, size distribution of parasitized fish, and patterns of host and attachment site specificity. Our results reveal high levels of attachment area fidelity for each leech species. These results suggest skin thickness and density of the vascular network constrain leech attachment sites and further suggest trophic transmission to be an important axis of parasitization. We also demonstrate that, while leech species appear to be clustered spatially, this clustering does not appear to be correlated with fish biomass. This study illuminates the complex interactions among fish hosts and leech parasites in the Southern Ocean and lays the groundwork for future studies of Antarctic marine leech ecology that can aid in forecasting how host-parasite interactions may shift in the face of ongoing climate change.

ecology↗