Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 289
Filtrar
1.
Sci Data ; 8(1): 60, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33574331

RESUMO

Caligus rogercresseyi, commonly known as sea louse, is an ectoparasite copepod that impacts the salmon aquaculture in Chile, causing losses of hundreds of million dollars per year. In this study, we report a chromosome-scale assembly of the sea louse (C. rogercresseyi) genome based on single-molecule real-time sequencing (SMRT) and proximity ligation (Hi-C) analysis. Coding RNAs and non-coding RNAs, and specifically long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) were identified through whole transcriptome sequencing from different life stages. A total of 23,686 protein-coding genes and 12,558 non-coding RNAs were annotated. In addition, 6,308 lncRNAs and 5,774 miRNAs were found to be transcriptionally active from larvae to adult stages. Taken together, this genomic resource for C. rogercresseyi represents a valuable tool to develop sustainable control strategies in the salmon aquaculture industry.


Assuntos
Copépodes/genética , MicroRNAs/genética , RNA Longo não Codificante/genética , Transcriptoma , Animais , Cromossomos , Copépodes/patogenicidade , Doenças dos Peixes/parasitologia , Estágios do Ciclo de Vida/genética , Salmão/parasitologia
2.
Ecotoxicol Environ Saf ; 203: 111029, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888609

RESUMO

The chitin synthesis inhibitor teflubenzuron (TFB) is a feed antiparasitic agents used to impede molting of the salmon lice, an ecto-parasite that severely affects the salmon industry. Low absorption of oral administered TFB may cause elevated concentrations in the feces discharged from the salmon into the benthic environment. The polychaete Capitella sp. are often dominant in such habitats and consume organic waste deposited on the sediment. In the present study, Capitella sp. were exposed to doses of TFB in salmon feed of 1, 2 and 4 g TFB kg-1 (0 g TFB kg-1 in control group) over an experimental period of 32 days. Cumulative mortality was 12%-15% in both treatment groups with 1 and 2 g TFB kg-1 and reached 27% in the group with 4 g TFB kg-1. Only the highest dose (4 g TFB kg-1) negatively affected feed intake, growth and respiration of the polychaetes while food conversion efficiency was not affected. At the end of the experiment, the concentrations of TFB in the Capitella sp. were high, in the range of 9.24-10.32 µg g-1 for the three treatment groups. It was suggested that a maximum level of absorption rate was reached, also for the lowest dose. High concentrations of TFB in the Capitella sp. might pose a risk to crustaceans that forage for polychaetes in the vicinity of fish farms. We conclude that the effects of TFB on Capitella sp. may therefore primarily be to the predators rather than the Capitella sp.


Assuntos
Antiparasitários/toxicidade , Benzamidas/toxicidade , Bioacumulação , Sedimentos Geológicos/química , Poliquetos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antiparasitários/metabolismo , Benzamidas/metabolismo , Copépodes/efeitos dos fármacos , Relação Dose-Resposta a Droga , Pesqueiros , Modelos Teóricos , Poliquetos/metabolismo , Salmão/parasitologia , Análise de Sobrevida , Poluentes Químicos da Água/metabolismo
3.
Parasite Immunol ; 42(8): e12731, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32403169

RESUMO

The salmon louse Lepeophtheirus salmonis (Lsal) is an ectoparasitic copepod that exerts immunomodulatory and physiological effects on its host Atlantic salmon. Over 30 years of research on louse biology, control, host responses and the host-parasite relationship has provided a plethora of information on the intricacies of host resistance and parasite adaptation. Atlantic salmon exhibit temporal and spatial impairment of the immune system and wound healing ability during infection. This immunosuppression may render Atlantic salmon less tolerant to stress and other confounders associated with current management strategies. Contrasting susceptibility of salmonid hosts exists, and early pro-inflammatory Th1 type responses are associated with resistance. Rapid cellular responses to larvae appear to tip the balance of the host-parasite relationship in favour of the host, preventing severe immune-physiological impacts of the more invasive adults. Immunological, transcriptomic, genomic and proteomic evidence suggests pathological impacts occur in susceptible hosts through modulation of host immunity and physiology via pharmacologically active molecules. Co-evolutionary and farming selection pressures may have incurred preference of Atlantic salmon as a host for Lsal reflected in their interactome. Here, we review host-parasite interactions at the primary attachment/feeding site, and the complex life stage-dependent molecular mechanisms employed to subvert host physiology and immune responses.


Assuntos
Copépodes/imunologia , Doenças dos Peixes/parasitologia , Interações Hospedeiro-Parasita/imunologia , Salmão/imunologia , Salmão/parasitologia , Animais , Suscetibilidade a Doenças/imunologia , Doenças dos Peixes/imunologia , Tolerância Imunológica/imunologia , Larva/imunologia , Proteômica , Salmão/genética , Células Th1/imunologia , Transcriptoma , Cicatrização/imunologia
4.
Proc Natl Acad Sci U S A ; 117(10): 5358-5363, 2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-32094163

RESUMO

Although aerobic respiration is a hallmark of eukaryotes, a few unicellular lineages, growing in hypoxic environments, have secondarily lost this ability. In the absence of oxygen, the mitochondria of these organisms have lost all or parts of their genomes and evolved into mitochondria-related organelles (MROs). There has been debate regarding the presence of MROs in animals. Using deep sequencing approaches, we discovered that a member of the Cnidaria, the myxozoan Henneguya salminicola, has no mitochondrial genome, and thus has lost the ability to perform aerobic cellular respiration. This indicates that these core eukaryotic features are not ubiquitous among animals. Our analyses suggest that H. salminicola lost not only its mitochondrial genome but also nearly all nuclear genes involved in transcription and replication of the mitochondrial genome. In contrast, we identified many genes that encode proteins involved in other mitochondrial pathways and determined that genes involved in aerobic respiration or mitochondrial DNA replication were either absent or present only as pseudogenes. As a control, we used the same sequencing and annotation methods to show that a closely related myxozoan, Myxobolus squamalis, has a mitochondrial genome. The molecular results are supported by fluorescence micrographs, which show the presence of mitochondrial DNA in M. squamalis, but not in H. salminicola. Our discovery confirms that adaptation to an anaerobic environment is not unique to single-celled eukaryotes, but has also evolved in a multicellular, parasitic animal. Hence, H. salminicola provides an opportunity for understanding the evolutionary transition from an aerobic to an exclusive anaerobic metabolism.


Assuntos
Genoma Mitocondrial , Interações Hospedeiro-Parasita , Myxozoa/classificação , Myxozoa/genética , Salmão/parasitologia , Animais , Filogenia
5.
Parasitol Res ; 119(2): 513-518, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31848744

RESUMO

Diphyllobothriasis is a parasitic fish-borne disease caused by tapeworms of the genus Dibothriocephalus (=Diphyllobothrium). The majority of reported cases are attributed to D. latum, based on morphological identification of eggs or proglottids. However, numerous reports in recent years suggested that other Dibothriocephalus species could be involved in human infections, mainly after consumption of salmonid fish. Among these, D. nihonkaiense has been predominantly reported from Eastern Asia and probably underestimated in the rest of the world. We report here a clinical case of D. nihonkaiense in a French patient (without history of travel abroad) after consumption of salmon. Suspected on morphological characteristics, the final identification of D. nihonkaiense was performed using molecular methods by sequencing nad1, cox1, and 5.8S rRNA (containing ITS1 and 2) genes sequences. The patient was successfully treated by a single dose of praziquantel. Reports of diphyllobothriasis due to D. nihonkaiense are rare outside Asia, but worldwide demand of seafood could lead to the globalization of cases and reflect the need to monitor the distribution of Dibothriocephalus species. Thus, clinical parasitologists should be aware of this risk and able to raise the possibility of infections by non-endemic Dibothriocephalus species in order to use the proper molecular tools.


Assuntos
Anti-Helmínticos/uso terapêutico , Difilobotríase/diagnóstico , Adulto , Animais , DNA de Helmintos , Difilobotríase/tratamento farmacológico , Difilobotríase/etiologia , Difilobotríase/parasitologia , Diphyllobothrium , Doenças dos Peixes/parasitologia , França , Humanos , Masculino , Técnicas de Diagnóstico Molecular , Praziquantel/uso terapêutico , Salmão/parasitologia , Alimentos Marinhos/parasitologia , Análise de Sequência de DNA
6.
Parasit Vectors ; 12(1): 563, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31775848

RESUMO

BACKGROUND: The salmon louse (Lepeophtheirus salmonis) infests farmed and wild salmonid fishes, causing considerable economic damage to the salmon farming industry. Infestations of farmed salmon are controlled using a combination of non-medicinal approaches and veterinary drug treatments. While L. salmonis has developed resistance to most available salmon delousing agents, relatively little is known about the molecular mechanisms involved. Members of the cytochrome P450 (CYP) superfamily are typically monooxygenases, some of which are involved in the biosynthesis and metabolism of endogenous compounds, while others have central roles in the detoxification of xenobiotics. In terrestrial arthropods, insecticide resistance can be based on the enhanced expression of CYPs. The reported research aimed to characterise the CYP superfamily in L. salmonis and assess its potential roles in drug resistance. METHODS: Lepeophtheirus salmonis CYPs were identified by homology searches of the genome and transcriptome of the parasite. CYP transcript abundance in drug susceptible and multi-resistant L. salmonis was assessed by quantitative reverse transcription PCR, taking into account both constitutive expression and expression in parasites exposed to sublethal levels of salmon delousing agents, ecdysteroids and environmental chemicals. RESULTS: The above strategy led to the identification of 25 CYP genes/pseudogenes in L. salmonis, making its CYP superfamily the most compact characterised for any arthropod to date. Lepeophtheirus salmonis possesses homologues of a number of arthropod CYP genes with roles in ecdysteroid metabolism, such as the fruit fly genes disembodied, shadow, shade, spook and Cyp18a1. CYP transcript expression did not differ between one drug susceptible and one multi-resistant strain of L. salmonis. Exposure of L. salmonis to emamectin benzoate or deltamethrin caused the transcriptional upregulation of certain CYPs. In contrast, neither ecdysteroid nor benzo[a]pyrene exposure affected CYP transcription significantly. CONCLUSIONS: The parasite L. salmonis is demonstrated to possess the most compact CYP superfamily characterised for any arthropod to date. The complement of CYP genes in L. salmonis includes conserved CYP genes involved in ecdysteroid biosynthesis and metabolism, as well as drug-inducible CYP genes. The present study does not provide evidence for a role of CYP genes in the decreased susceptibility of the multiresistant parasite strain studied.


Assuntos
Copépodes/genética , Sistema Enzimático do Citocromo P-450/genética , Salmão/parasitologia , Animais , Aquicultura , Copépodes/efeitos dos fármacos , Doenças dos Peixes/parasitologia , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Transcriptoma
7.
Proc Biol Sci ; 286(1904): 20190428, 2019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-31185867

RESUMO

Regional variation in climate can generate differences in population dynamics and stage structure. Where regional differences exist, the best approach to pest management may be region-specific. Salmon lice are a stage-structured marine copepod that parasitizes salmonids at aquaculture sites worldwide, and have fecundity, development and mortality rates that depend on temperature and salinity. We show that in Atlantic Canada and Norway, where the oceans are relatively cold, salmon lice abundance decreases during the winter months, but ultimately increases from year to year, while in Ireland and Chile, where the oceans are warmer, the population size grows monotonically without any seasonal declines. In colder regions, during the winter the stage structure is dominated by the adult stage, which is in contrast to warmer regions where all stages are abundant year round. These differences translate into region-specific recommendations for management: regions with slower population growth have lower critical stocking densities, and regions with cold winters have a seasonal dependence in the timing of follow-up chemotherapeutic treatments. Predictions of our salmon lice model agree with empirical data, and our approach provides a method to understand the effects of regional differences in climate on salmon lice dynamics and management.


Assuntos
Clima , Copépodes/fisiologia , Salmão/parasitologia , Temperatura , Animais , Aquicultura , Canadá , Chile , Irlanda , Modelos Teóricos , Noruega , Oceanos e Mares , Densidade Demográfica , Dinâmica Populacional , Estações do Ano
8.
Transbound Emerg Dis ; 66(5): 2107-2119, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31155828

RESUMO

This study documents the development of a non-lethal sampling method to recover gyrodactylid parasites from large numbers of fish that will underpin an improved surveillance strategy for Gyrodactylus salaris. A review of published literature identified over 80 compounds that have previously been tested against gyrodactylids or closely related parasite species. Five safe and relatively fast-acting compounds were selected for testing to determine their efficiency in removing gyrodactylids from host fish in small-scale aquaria trials using three-spined stickleback infected with Gyrodactylus gasterostei as a model host-parasite system. The most effective compound was hydrogen peroxide; short-duration exposure (3 min) achieved a parasite detection sensitivity of 80%-89%. The practicality of exposing farmed salmonids to hydrogen peroxide for G. salaris surveillance was tested in the field by conducting a parasite recovery trial using a brown trout stock endemically infected with G. truttae and G. derjavinoides and comparing this to the whole-body examination procedure currently conducted by UK authorities. Significantly more parasites were recovered after exposing fish to hydrogen peroxide and filtering the treatment solution than by direct whole-body examination of killed fish (mean: 225 vs. 138 parasites per fish). The gyrodactylid recovery rate of the two methods was 84.6% and 51.9%, respectively. A comparison of timings for the two methods indicated scope for significant time savings in adopting the chemical screening method. The study demonstrated that hydrogen peroxide bath treatment may be successfully applied to the surveillance of gyrodactylid parasites and established as a non-lethal method for sampling farmed and wild fish. This approach has the potential to reduce resources required to collect and isolate parasites for diagnostic testing and improve the sensitivity and confidence of surveillance programmes designed to demonstrate freedom from disease, thus underpinning a robust and defensible surveillance strategy for G. salaris for the UK aquatic animal disease contingency plan.


Assuntos
Doenças dos Peixes/parasitologia , Peróxido de Hidrogênio/administração & dosagem , Platelmintos/efeitos dos fármacos , Salmão/parasitologia , Trematódeos/efeitos dos fármacos , Infecções por Trematódeos/tratamento farmacológico , Truta/parasitologia , Animais , Aquicultura
9.
J Fish Dis ; 42(7): 985-989, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31044445

RESUMO

The sea louse, Lepeophtheirus salmonis (Krøyer 1837), is a significant parasite of farmed salmon throughout the Northern Hemisphere. Management of on-farm louse populations can be improved by understanding the role that wild fish play in sustaining and providing refuge for the local population of sea lice. In this study, 1,064 sticklebacks were captured. Of these animals, 176 individuals were carrying a total of 238 sea lice, yielding a prevalence and intensity of 16.5% and 1.4 lice per fish, respectively. Detailed examination of the sea lice on the three-spined sticklebacks captured in Cobscook Bay found two L. salmonis individuals using three-spined sticklebacks as hosts. A 2012 survey of wild fish in Cobscook Bay, Maine, found multiple wild hosts for Caligus elongatus (von Nordmann 1832), including three-spined sticklebacks (Gasterosteus aculeatus L.), but no L. salmonis were found in this earlier study.


Assuntos
Copépodes/patogenicidade , Ectoparasitoses/veterinária , Doenças dos Peixes/parasitologia , Salmão/parasitologia , Smegmamorpha/parasitologia , Animais , Estuários , Maine/epidemiologia , Prevalência
10.
Parasit Vectors ; 12(1): 267, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138323

RESUMO

BACKGROUND: Diphyllobothriosis is an intestinal cestodosis caused by tapeworms of the family Diphyllobothriidae. In France, endemic cases are limited to south-east and due to Dibothriocephalus latus. In this paper, we investigate a series of seven cases of diphyllobothriosis in the non-endemic French region of Brittany. All have been diagnosed between 2016 and 2018 at the University Hospital of Rennes. METHODS: Parasites were identified by their morphological features and by phylogenetic analysis of the cox1 gene. Phylogenetic tree was built using maximum likelihood criterion under the GTR+G+I model and 2000 bootstrap replicates. A form was sent to all patients to collect data concerning clinical signs and possible sources of infection. RESULTS: All cases were due to Dibothriocephalus nihonkaiensis, a species strictly distributed in the North Pacific. Epidemiological investigation showed that the parasite was probably acquired in France, after consumption of Japanese food containing raw salmon. All patients presented with at least abdominal pain and fatigue except for one patient who had no symptoms. CONCLUSIONS: To our knowledge, this case series is the most important cohort of allochthonous diphyllobothriosis described in Europe. This sudden emergence raises concern about foodborne infections, highlighting (i) risky food habits in absence of adequate sanitary control; and (ii) the breaking of the rule of geographical restriction due to globalization and worldwide trades.


Assuntos
Difilobotríase/diagnóstico , Diphyllobothrium/isolamento & purificação , Alimentos Crus/parasitologia , Alimentos Marinhos/parasitologia , Adolescente , Adulto , Animais , Antiparasitários/uso terapêutico , Estudos de Coortes , Ciclo-Oxigenase 1/genética , Difilobotríase/tratamento farmacológico , Diphyllobothrium/genética , Feminino , França/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Filogenia , Salmão/parasitologia , Adulto Jovem
11.
BMC Biol ; 17(1): 19, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30823887

RESUMO

BACKGROUND: Spironucleus salmonicida is an anaerobic parasite that can cause systemic infections in Atlantic salmon. Unlike other diplomonad parasites, such as the human pathogen Giardia intestinalis, Spironucleus species can infiltrate the blood stream of their hosts eventually colonizing organs, skin and gills. How this presumed anaerobe can persist and invade oxygenated tissues, despite having a strictly anaerobic metabolism, remains elusive. RESULTS: To investigate how S. salmonicida response to oxygen stress, we performed RNAseq transcriptomic analyses of cells grown in the presence of oxygen or antioxidant-free medium. We found that over 20% of the transcriptome is differentially regulated in oxygen (1705 genes) and antioxidant-depleted (2280 genes) conditions. These differentially regulated transcripts encode proteins related to anaerobic metabolism, cysteine and Fe-S cluster biosynthesis, as well as a large number of proteins of unknown function. S. salmonicida does not encode genes involved in the classical elements of oxygen metabolism (e.g., catalases, superoxide dismutase, glutathione biosynthesis, oxidative phosphorylation). Instead, we found that genes encoding bacterial-like oxidoreductases were upregulated in response to oxygen stress. Phylogenetic analysis revealed some of these oxygen-responsive genes (e.g., nadh oxidase, rubrerythrin, superoxide reductase) are rare in eukaryotes and likely derived from lateral gene transfer (LGT) events into diplomonads from prokaryotes. Unexpectedly, we observed that many host evasion- and invasion-related genes were also upregulated under oxidative stress suggesting that oxygen might be an important signal for pathogenesis. CONCLUSION: While oxygen is toxic for related organisms, such as G. intestinalis, we find that oxygen is likely a gene induction signal for host invasion- and evasion-related pathways in S. salmonicida. These data provide the first molecular evidence for how S. salmonicida could tolerate oxic host environments and demonstrate how LGT can have a profound impact on the biology of anaerobic parasites.


Assuntos
Anaerobiose/genética , Diplomonadida/genética , Oxigênio/administração & dosagem , Estresse Fisiológico/genética , Animais , Diplomonadida/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Salmão/parasitologia
12.
J Fish Dis ; 42(4): 533-547, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30742305

RESUMO

In response to concerns that novel infectious agents were introduced through the movement of eggs as Atlantic salmon aquaculture developed in British Columbia (BC), Canada, we estimated the prevalence of infectious agents in archived return-migrating Sockeye salmon, from before and during aquaculture expansion in BC (1985-94). Of 45 infectious agents assessed through molecular assays in 652 samples, 23 (7 bacterial, 2 viral and 14 parasitic) were detected in liver tissue from six regions in BC. Prevalence ranged from 0.005 to 0.83 and varied significantly by region and year. Agent diversity ranged from 0 to 12 per fish (median 4), with the lowest diversity observed in fish from the Trans-Boundary and Central Coast regions. Agents known to be endemic in Sockeye salmon in BC, including Flavobacterium psychrophilum, Infectious haematopoietic necrosis virus, Ceratonova shasta and Parvicapsula minibicornis, were commonly observed. Others, such as Kudoa thyrsites and Piscirikettsia salmonis, were also detected. Surprisingly, infectious agents described only recently in BC salmon, Ca. Branchiomonas cysticola, Parvicapsula pseudobranchicola and Paranucleospora theridion, were also detected, indicating their potential presence prior to the expansion of the aquaculture industry. In general, our data suggest that agent distributions may not have substantially changed because of the salmon aquaculture industry.


Assuntos
Infecções Bacterianas/veterinária , Doenças Parasitárias em Animais/epidemiologia , Salmão/microbiologia , Salmão/parasitologia , Salmão/virologia , Viroses/veterinária , Animais , Aquicultura , Infecções Bacterianas/epidemiologia , Colúmbia Britânica/epidemiologia , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/microbiologia , Doenças dos Peixes/virologia , Prevalência , Salmo salar , Bancos de Tecidos , Viroses/epidemiologia
14.
Epidemics ; 26: 9-22, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30172577

RESUMO

The parasitic salmon louse constrains growth in the Norwegian salmon farming industry through density dependent host-parasite interaction. Hence, there is a need for insight into how increases in salmon production, varying spatial organisation of the production and pest control strategies affect salmon louse population dynamics. Here we present a new salmon louse model for exploring effects of varying salmon farming conditions on spatio-temporal abundances of the parasite. The salmon louse model is partly stage-structured, comprising of (i) adult female lice and (ii) other mobile stages of lice. The abundance of adult females depend on survival of females from previous weeks and recruitment from the other mobile group of lice. The other mobiles also depend on survival of other mobiles from previous weeks, as well as recruitment from the previous generation of reproducing adult females from the same farm or from farms in the neighbourhood. In addition, expected abundances of the two stage-groups are modelled as functions of biological and physical covariates. The model is fitted to weekly salmon farm data covering all marine farms producing salmonids along the Norwegian cost over the years 2012-2016. Among novel results from fitting the model are estimates of the time-lag structure representing recruitment of other mobile lice from the previous generation adult females for different temperatures. Furthermore, the model estimates how various factors affect the susceptibility of fish on farms to louse infection and effects of treatments to control infection. Finally, the model estimates density dependent effects of increasing the number of fish in farms and of increasing the numbers of farms, on the rate of recruitment of other mobile lice. Analytically, the parameters representing density dependencies suggest that few farms with many fish and large between farm distances is effective in terms of minimising the overall output of salmon lice infection.


Assuntos
Aquicultura , Copépodes/parasitologia , Doenças dos Peixes/epidemiologia , Salmão/parasitologia , Animais , Feminino , Doenças dos Peixes/parasitologia , Interações Hospedeiro-Parasita , Noruega , Dinâmica Populacional , Salmonidae/parasitologia
15.
Parasit Vectors ; 11(1): 570, 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30376873

RESUMO

BACKGROUND: Control of the sea louse Caligus rogercresseyi in the Chilean salmonid industry is reliant on chemical treatments. Azamethiphos was introduced in 2013, although other organophosphates were previously used. In 2014, reduced sensitivity to azamethiphos was detected in the Los Lagos Region using bioassays. The main target of organophosphates is the enzyme acetylcholinesterase (AChE). Mutations in the AChE gene are the main cause of organophosphate resistance in arthropods, including other sea lice. In the present study, we aimed to characterize C. rogercresseyi AChE(s) gene(s) and to study the association between AChE variants and azamethiphos resistance in this sea louse species. METHODS: Samples of adult male and female C. rogercresseyi were collected in the Los Lagos Region in 2014. Twenty-four hour exposure bioassays with azamethiphos were performed to select sensitive and resistant lice. The full-length cDNA coding sequences encoding for two AChEs in C. rogercresseyi were molecularly characterized. One of the AChE genes was screened by direct sequencing in the azamethiphos-selected lice to search for variants. An additional louse sampling was performed before and after an azamethiphos treatment in the field in 2017 to validate the findings. RESULTS: The molecular analysis revealed two putative AChEs in C. rogercresseyi. In silico analysis and 3D modelling of the protein sequences identified both of them as invertebrate AChE type 1; they were named C. rogercresseyi AChE1a and 1b. AChE1a had the characteristics of the main synaptic AChE, while AChE1b lacked some of the important amino acids of a typical AChE. A missense change found in the main synaptic AChE (1a), F318F/V (F290 in Torpedo californica), was associated with survival of C. rogercresseyi at high azamethiphos concentrations (bioassays and field treatment). The amino acid change was located in the acyl pocket of the active-site gorge of the protein. CONCLUSIONS: The present study demonstrates the presence of two types of AChE1 genes in C. rogercresseyi. Although enzymatic assays are needed, AChE1a is most probably the main synaptic AChE. The function of AChE1b is unknown, but evidence points to a scavenger role. The AChE1a F/V318 variant is most probably involved in organophosphate resistance, and can be a good marker for resistance monitoring.


Assuntos
Acetilcolinesterase/genética , Antiparasitários/farmacologia , Copépodes/enzimologia , Doenças dos Peixes/parasitologia , Polimorfismo Genético/genética , Salmão/parasitologia , Sequência de Aminoácidos , Animais , Biomarcadores , Chile , Copépodes/efeitos dos fármacos , Copépodes/genética , Resistência a Medicamentos , Feminino , Masculino , Organotiofosfatos/farmacologia , Filogenia , Alinhamento de Sequência/veterinária
16.
Genet Sel Evol ; 50(1): 47, 2018 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-30285629

RESUMO

BACKGROUND: Macroparasites, such as ticks, lice, and helminths, are a concern in livestock and aquaculture production, and can be controlled by genetic improvement of the host population. Genetic improvement should aim at reducing the rate at which parasites spread across the farmed population. This rate is determined by the basic reproduction ratio, i.e. [Formula: see text], which is the appropriate breeding goal trait. This study aims at providing a method to derive the economic value of [Formula: see text]. METHODS: Costs of a disease are the sum of production losses and expenditures on disease control. Genetic improvement of [Formula: see text] lowers the loss-expenditure frontier. Its economic effect depends on whether the management strategy is optimized or not. The economic value may be derived either from the reduction in losses with constant expenditures or from the reduction in expenditures with constant losses. RESULTS: When [Formula: see text] ≤ 1, the economic value of a further reduction is zero because there is no risk of a major epidemic. When [Formula: see text] > 1 and management is optimized, the economic value increases with decreasing values of [Formula: see text], because both the mean number of parasites per host and frequency of treatments decrease at an increasing rate when [Formula: see text] decreases. When [Formula: see text] > 1 and management is not optimized, the economic value depends on whether genetic improvement is used for reducing expenditures or losses. For sea lice in salmon, the economic value depends on a reduction in expenditures with constant losses, and is estimated to be 0.065€/unit [Formula: see text]/kg production. DISCUSSION: Response to selection for measures of disease prevalence cannot be predicted from quantitative genetic theory alone. Moreover, many studies fail to address the issue of whether genetic improvement results in reduced losses or expenditures. Using [Formula: see text] as the breeding goal trait, weighed by its appropriate economic value, avoids these issues. CONCLUSION: When management is optimized, the economic value increases with decreasing values of [Formula: see text] (until the threshold of [Formula: see text], where it drops to zero). When management is not optimized, the economic value depends on whether genetic improvement is used for reduced expenditures or production losses. For sea lice in salmon, the economic value is estimated to be 0.065 €/unit [Formula: see text]/kg production.


Assuntos
Efeitos Psicossociais da Doença , Doenças dos Peixes/economia , Doenças Parasitárias/economia , Salmão/genética , Animais , Copépodes/patogenicidade , Doenças dos Peixes/genética , Doenças Parasitárias/genética , Reprodução , Salmão/parasitologia , Salmão/fisiologia , Seleção Artificial
17.
Vet Rec ; 183(12): 383, 2018 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-30061113

RESUMO

Currently, cleaner fish are one of the most widely used sea lice control strategies in Atlantic salmon aquaculture. Two species are currently being farmed in North Atlantic countries, ballan wrasse (Labrus bergylta) and lumpfish (Cyclopterus lumpus), and the sector in most countries is rapidly expanding towards self-sufficiency. The species are very different both in terms of their biology and life histories and, consequently, production and husbandry methods must be tailored to each species. There are numerous health challenges currently experienced in both species, with bacterial and parasitic diseases being the most prevalent, and cohabitation with salmon may increase the risk of disease. Good husbandry and routine health monitoring are essential, although treatment is often required when disease outbreaks occur. Ballan wrasse and lumpfish are both proven to be effective salmon delousers, although delousing efficacy can be variable in farmed fish; the provision of suitable habitat and acclimation to net-pen conditions may encourage natural behaviours, including delousing, and the use of operational welfare indicators can highlight potential welfare issues. Cleaner fish research is progressing rapidly, although much of the basic knowledge regarding the species' biology remains unknown. The simultaneous domestication of two new marine aquaculture species is a significant challenge demanding sustained effort and funding over a prolonged period of time. Research must focus on enhancing the robustness of the farmed stocks and increasing hatchery outputs to meet the urgent demands from the salmon sector and protect wild stocks from overfishing.


Assuntos
Copépodes , Ectoparasitoses/veterinária , Doenças dos Peixes/prevenção & controle , Pesqueiros , Controle Biológico de Vetores/métodos , Animais , Ectoparasitoses/parasitologia , Ectoparasitoses/prevenção & controle , Comportamento Alimentar/fisiologia , Doenças dos Peixes/parasitologia , Peixes , Perciformes/fisiologia , Salmão/parasitologia
18.
J Parasitol ; 104(6): 645-650, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30142293

RESUMO

The distribution of the freshwater myxozoan parasite Ceratonova shasta in the Pacific Northwest of North America is limited to overlap in the ranges of its 2 hosts: the polychaete Manyunkia sp., and Pacific salmonids. Studies in the Klamath River (Oregon/California) and Deschutes River (Oregon), showed that the parasite population is comprised of multiple sympatric genotypes, some of which correlate with particular salmonid host species and with differences in clinical disease in those hosts. The 3 primary genotypes O, I, and II are defined by the number of a specific tri-nucleotide repeat in the internal transcribed spacer-1 region. To understand the spatial extent of host-parasite genotype patterns, we sequenced the parasite from 448 salmonid fishes from river basins in California, Oregon, Washington, Idaho, and British Columbia, Canada. We sampled intestinal tissues from 6 species of salmon and trout, both those that exist naturally with the parasite (sympatric) and those that do not naturally co-occur with the parasite and were exposed artificially in cages (allopatric). In most river basins we detected the same primary C. shasta genotypes that were described from the Klamath and Deschutes rivers, and we did not detect any novel primary genotypes. Host-parasite genotype patterns were consistent with previous data: genotype O was found in sympatric trout only; genotype I predominantly in Chinook salmon, and genotype II in all 6 fish species but dominant in coho salmon. Our findings of widespread, consistent host-parasite genotype patterns support the hypothesis that C. shasta has a long evolutionary history with salmonid fishes in the Pacific Northwest, and impels additional studies to determine if these parasite genotypes should be considered different species.


Assuntos
Doenças dos Peixes/parasitologia , Myxozoa/fisiologia , Doenças Parasitárias em Animais/parasitologia , Salmão/parasitologia , Truta/parasitologia , Adaptação Biológica , Animais , Evolução Biológica , Colúmbia Britânica , California , DNA/isolamento & purificação , Água Doce/parasitologia , Genótipo , Interações Hospedeiro-Parasita/genética , Enteropatias Parasitárias/parasitologia , Enteropatias Parasitárias/veterinária , Intestinos/parasitologia , Myxozoa/classificação , Myxozoa/genética , Oregon , Rios/parasitologia , Washington
19.
Transbound Emerg Dis ; 65(6): 1474-1481, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30144307

RESUMO

International biodiversity assessments often overlook the role of emerging infectious pathogens in the decline of freshwater fish populations despite the many examples of emerging diseases in other more visible taxa on a global scale. Whilst the introduction of the rosette agent Sphaerothecum destruens in Europe remained an epidemiological enigma, recent findings have shown that this parasite arrived in Europe with the introduction of the healthy carrier Pseudorasbora parva from China nearly 60 years ago and its emergence went unnoticed for over 45 years despite its severe impact on European fish biodiversity. Recent reports on the host and pathogen phylogeny point towards an ancient host-pathogen co-evolution with direct implications on disease risk. Here, we postulate that the observed rapid population decline of native fish species following their infection with virulent strains of S. destruens has underpinned the rapid establishment of P. parva populations during the invasion process. We reviewed the existing evidence supporting the claim of an S. destruens' emergence worldwide and also suggest that the origin of the US strains is to be found among contaminated Asian Oncorhynchus tshawytscha living in sympatry with native Asian P. parva population. Finally, several important preventative steps are suggested as a way to manage the impact of S. destruens on local fish communities.


Assuntos
Doenças Transmissíveis Emergentes/veterinária , Cyprinidae/parasitologia , Doenças dos Peixes/epidemiologia , Infecções por Mesomycetozoea/epidemiologia , Mesomycetozoea , Animais , China/epidemiologia , Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/parasitologia , Europa (Continente)/epidemiologia , Doenças dos Peixes/parasitologia , Água Doce , Infecções por Mesomycetozoea/parasitologia , Filogenia , Salmão/parasitologia
20.
J Fish Biol ; 93(2): 263-271, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29956312

RESUMO

We conducted a manipulative field experiment to determine whether the leaping behaviour of wild juvenile sockeye salmon Oncorhynchus nerka dislodges ectoparasitic sea lice Caligus clemensi and Lepeophtheirus salmonis by comparing sea-lice abundances between O. nerka juveniles prevented from leaping and juveniles allowed to leap at a natural frequency. Juvenile O. nerka allowed to leap had consistently fewer sea lice after the experiment than fish that were prevented from leaping. Combined with past research, these results imply potential costs due to parasitism and indicate that the leaping behaviour of juvenile O. nerka does, in fact, dislodge sea lice.


Assuntos
Comportamento Animal , Copépodes , Salmão/parasitologia , Animais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...