Hook, Line and Infection

Stewart, Alexander; Jackson, Joe; Barber, Iain; Eizaguirre, Christophe; Paterson, Rachel A.; West, Pieter van; Williams, C.; Cable, Joanne

doi:10.1016/bs.apar.2017.07.001

Cited by 28 publications

(20 citation statements)

References 337 publications

(495 reference statements)

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“…Morphologically, S1 and S3 share the ability to produce sexual structures in vitro which are characteristic of the isolates of a non-pathogenic nature obtained from water or aquatic animals other than infected salmonids (Diéguez-Uribeondo et al, 2007). A sexual phase increases the survival chances of oomycetes exposed to the challenging environmental conditions such as desiccation or high temperature (Stewart et al, 2017). Therefore, the S1 and S3 strains can possibly be transmitted to hosts by means of asexual propagation and can also survive difficult conditions by forming sexual oogonia structures.…”

Section: Discussionmentioning

confidence: 99%

Saprolegnia molecular phylogeny among farmed teleosts in Nova Scotia, Canada

Sarowar

Cusack

Duston

2019

Journal of Fish Diseases

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To identify the pathogens causing saprolegniosis among farmed fish in Nova Scotia, 172 infected tissues and 23 water samples were collected from six species of teleosts: Atlantic salmon (Salmo salar), brown trout (Salmo trutta), Arctic charr (Salvelinus alpinus), brook trout (Salvelinus fontinalis), striped bass (Morone saxatilis) and rainbow trout (Oncorhynchus mykiss) at nine facilities over a 600 km range. Following laboratory culture, 132 isolates were recovered. Six species of oomycetes were identified from analysis of the internal transcribed spacer (ITS) sequence of the nrDNA: Saprolegnia parasitica, Saprolegnia ferax, Saprolegnia diclina, Saprolegnia aenigmatica, Saprolegnia torulosa, Saprolegnia sp. and Pythiopsis cymosa. Further phylogenetic analyses of the ITS and cytochrome c oxidase subunit 1 (Cox1) regions revealed four strains of Saprolegnia parasitica (named here as S1, S2, S3 and S4), of which S1 and S2 were common (37% and 42% of the isolates), and two strains of S. ferax. Among S. parasitica, S2 and S3 are more closely related to each other than to S1 based on the phylogenetic analyses and predicted RNA secondary structure of the ITS region. Sexual structures with a similar morphology were formed by S1 and S3 in vitro, but were not formed by S2.

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Section: Discussionmentioning

confidence: 99%

Saprolegnia molecular phylogeny among farmed teleosts in Nova Scotia, Canada

Sarowar

Cusack

Duston

2019

Journal of Fish Diseases

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“…Mycelia masses were washed in sterile dechlorinated water and then maintained for 3 days in 50% dechlorinated water, 50% water from tilapia stock tanks, at 15 °C to induce zoospore production. Heat-killed zoospores were produced by incubating at 60 °C for 1 h. A haemocytometer was used to quantify zoospore concentrations and zoospore suspensions were equilibrated to 24 °C before use [ 36 ].…”

Section: Methodsmentioning

confidence: 99%

Transcriptomic response to parasite infection in Nile tilapia (Oreochromis niloticus) depends on rearing density

et al. 2018

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BackgroundCaptive animal populations, be it for food production or conservation programmes, are often maintained at densities far beyond those in natural environments, which can have profound effects on behaviour, immune and stress levels, and ultimately welfare. How such alterations impact transcriptional responses to pathogen infection is a ‘different kettle of fish’ and remains poorly understood. Here, we assessed survival and gene expression profiles of infected fish reared at two different densities to elucidate potential functional genomic mechanisms for density-related differences in disease susceptibility.ResultsUtilising a whole-transcriptome sequencing (RNAseq) approach, we demonstrate that rearing density in tilapia (Oreochromis niloticus) significantly impacts susceptibility to the oomycete Saprolegnia parasitica, via altered transcriptional infection responses. Tilapia held at low densities have increased expression of genes related to stress, likely due to increased aggressive interactions. When challenged with Saprolegnia, low-density fish exhibit altered expression of inflammatory gene responses and enhanced levels of adaptive immune gene suppression compared to fish reared at higher density, resulting in significantly increased mortality rates. In addition, Saprolegnia infection substantially perturbs expression of circadian clock genes, with fish reared at low-density having higher levels of molecular clock dysregulation.ConclusionsOur results reveal the wide-scale impact of stocking density on transcriptional responses to infection and highlight the need to incorporate circadian biology into our understanding of disease dynamics in managed animals.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5098-7) contains supplementary material, which is available to authorized users.

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“…Increases in the abundance of endoparasites in fish of larger size are attributed to cumulative occurrences of the infection process. However, in order for an infection to be established, the niches of invasive parasite forms have to overlap with the host niches (Stewart et al, 2017). For endoparasites, these processes may be linked to cumulative behavioral or trophic changes along the life of the host (Holmes, 1990).…”

Section: Resultsmentioning

confidence: 99%

Metazoan endoparasites of <i>Brycon orbignyanus</i> (Characidae: Bryconinae) in a neotropical floodplain

Fernandes

Casali

Takemoto

2019

Acta Sci. Biol. Sci.

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Species richness and composition are central themes in community ecology of helminths because they improve the understanding of factors that determine community structure. Floodplain ecosystems and the environmental alterations induced by hydrological cycles are factors that maintain biodiversity over time, as observed in the Upper Paraná River floodplain, where the individuals of Brycon orbignyanus were collected. The objective of this study was to evaluate whether variables such as the richness and abundance of endoparasites are related to the fish size during different hydrological periods (high and low waters). A total of 163 endoparasites belonging to 13 species were collected in the 104 fish examined. Fish size had a positive correlation with mean diversity and abundance of the endoparasite infracommunity, supporting the idea that larger hosts are able to harbor a more abundant and diverse parasite infracommunity. The diversity of habitats provided by the floodplain can be considered the main factor explaining the differences between these attributes of parasite species. Variations in parasite richness between different hosts provide not only a good model for studies on community diversification but are also of great interest in species conservation. All parasite species found in B. orbignyanus were recorded for the first time in this host, especially in the Upper Paraná River floodplain.

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Hook, Line and Infection

Cited by 28 publications

References 337 publications

Saprolegnia molecular phylogeny among farmed teleosts in Nova Scotia, Canada

Saprolegnia molecular phylogeny among farmed teleosts in Nova Scotia, Canada

Transcriptomic response to parasite infection in Nile tilapia (Oreochromis niloticus) depends on rearing density

Metazoan endoparasites of <i>Brycon orbignyanus</i> (Characidae: Bryconinae) in a neotropical floodplain

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