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Karin Boxaspen - One of the best experts on this subject based on the ideXlab platform.

Juan G. Cárcamo - One of the best experts on this subject based on the ideXlab platform.

  • comparative pan genome analysis of piscirickettsia salmonis reveals genomic divergences within genogroups
    Frontiers in Cellular and Infection Microbiology, 2017
    Co-Authors: Cristian Molina, Patricio Sánchez, Guillermo Nourdingalindo, Daniela A Espinozarojas, Cristian Oliver, Pamela Ruiz, Luis Vargaschacoff, Juan G. Cárcamo
    Abstract:

    Piscirickettsia salmonis is the etiological agent of Salmonid rickettsial septicemia, a disease that seriously affects the Salmonid industry. Despite efforts to genomically characterize P. salmonis, functional information on the life cycle, pathogenesis mechanisms, diagnosis, treatment, and control of this fish pathogen remain lacking. To address this knowledge gap, the present study conducted an in silico pan-genome analysis of 19 P. salmonis strains from distinct geographic locations and genogroups. Results revealed an expected open pan-genome of 3,463 genes and a core-genome of 1,732 genes. Two marked genogroups were identified, as confirmed by phylogenetic and phylogenomic relationships to the LF-89 and EM-90 reference strains, as well as by assessments of genomic structures. Different structural configurations were found for the six identified copies of the ribosomal operon in the P. salmonis genome, indicating translocation throughout the genetic material. Chromosomal divergences in genomic localization and quantity of genetic cassettes were also found for the Dot/Icm type IVB secretion system. To determine divergences between core-genomes, additional pan-genome descriptions were compiled for the so-termed LF and EM genogroups. Open pan-genomes composed of 2,924 and 2,778 genes and core-genomes composed of 2,170 and 2,228 genes were respectively found for the LF and EM genogroups. The core-genomes were functionally annotated using the Gene Ontology, KEGG, and Virulence Factor databases, revealing the presence of several shared groups of genes related to basic function of intracellular survival and bacterial pathogenesis. Additionally, the specific pan-genomes for the LF and EM genogroups were defined, resulting in the identification of 148 and 273 exclusive proteins, respectively. Notably, specific virulence factors linked to adherence, colonization, invasion factors, and endotoxins were established. The obtained data suggest that these genes could be directly associated with inter-genogroup differences in pathogenesis and host-pathogen interactions, information that could be useful in designing novel strategies for diagnosing and controlling P. salmonis infection.

  • Draft Genome Sequence of Virulent Strain AUSTRAL-005 of Piscirickettsia salmonis, the Etiological Agent of Piscirickettsiosis
    Genome announcements, 2014
    Co-Authors: Alejandro J. Yáñez, Cristian Molina, Ronie E. Haro, Patricio Sánchez, Adolfo Isla, Julio Mendoza, Marcelo Rojas-herrera, Annette N. Trombert, Andrea X. Silva, Juan G. Cárcamo
    Abstract:

    We report here the draft genome sequence of a lethal pathogen of farmed Salmonids, Piscirickettsia salmonis strain AUSTRAL-005. This virulent strain was isolated in 2008 from Oncorhynchus mykiss farms, and multiple genes involved in pathogenicity, environmental adaptation, and metabolic pathways were identified.

  • broth microdilution protocol for minimum inhibitory concentration mic determinations of the intracellular Salmonid pathogen piscirickettsia salmonis to florfenicol and oxytetracycline
    Journal of Fish Diseases, 2014
    Co-Authors: Alejandro J. Yáñez, Jaime Figueroa, Ruben Avendanoherrera, K Valenzuela, C Matzner, Victor H Olavarria, Juan G. Cárcamo
    Abstract:

    Piscirickettsia salmonis is a facultative intracellular Gram-negative bacterium (Mauel, Ware & Smith 2008; Mikalsen et al. 2008) originally isolated from fish in Chile and constitutes one of the main problems in farmed Salmonids and marine fish worldwide (see reviews by Almendras & Fuentealba 1997; Mauel & Miller 2002; Fryer & Hedrick 2003). This fastidious pathogen was first observed in southern Chile in 1989 (Bravo & Campos 1989; Branson & Diaz-Mu~ noz 1991; Cvitanich, Garate & Smith 1991), then in western Canada (Brocklebank et al. 1992), Ireland (Rodger & Drinan 1993), Scotland (Grant et al. 1996), Norway (Olsen et al. 1997), eastern Canada (Cusack, Groman & Jones 2002) and southern USA (Arkush et al. 2005). Currently, an official report from the Chilean authorities indicates that piscirickettsiosis or Salmonid rickettsial septicaemia (SRS) caused by P. salmonis has a high prevalence with 68% of fish diagnosed as positive (www.sernapesca.cl). Treatments with antimicrobial drugs represent the only measure to control SRS in farmed fish. In fact, in 2010, its use in Chilean salmon farms added up to approximately 103 000 kg (www. sernapesca.cl). Chemotherapy with a fluorinated structural synthetic analogue to thiamphenicol and chloramphenicol, florfenicol (FLO) and oxytetracycline (OTC), two bacteriostatic agents with broad-spectrum activity, has often been the choice of drugs for treating the outbreaks. However, since their first use, the results of antimicrobial treatments have been inconsistent and have failed to effectively control SRS (Branson & Diaz-Mu~ noz 1991; Cvitanich et al. 1991). The irregular effects of the chemotherapy in controlling P. salmonis in Salmonids indicate that the bacterium has developed drug resistance. The drug resistance mechanisms for some fish pathogens have been studied but have not been characterized for P. salmonis (http://www.who.int/topics/foodborne_diseases/aquaculture_rep_13_16june2006% 20.pdf). Therefore, the appearance of potentially resistant isolates has raised efforts to provide data about the antimicrobial susceptibility of P. salmonis isolates to different antibiotics. Correspondence A J Y a~ nez, R Avenda~ no-Herrera and J G Carcamo, Interdisciplinary Center for Aquaculture Research (INCAR), V ictor Lamas 1290, PO Box 160-C, Concepci on, Chile (e-mails: ayanez@uach.cl, gcarcamo@uach. cl, ravendano@unab.cl)

Magne Aldrin - One of the best experts on this subject based on the ideXlab platform.

  • space time modelling of the spread of salmon lice between and within norwegian marine salmon farms
    PLOS ONE, 2013
    Co-Authors: Magne Aldrin, Bard Storvik, Anja B Kristoffersen, Peder A Jansen
    Abstract:

    Parasitic salmon lice are potentially harmful to Salmonid hosts and farm produced lice pose a threat to wild Salmonids. To control salmon lice infections in Norwegian Salmonid farming, numbers of lice are regularly counted and lice abundance is reported from all Salmonid farms every month. We have developed a stochastic space-time model where monthly lice abundance is modelled simultaneously for all farms. The set of farms is regarded as a network where the degree of contact between farms depends on their seaway distance. The expected lice abundance at each farm is modelled as a function of i) lice abundance in previous months at the same farm, ii) at neighbourhood farms, and iii) other, unspecified sources. In addition, the model includes explanatory variables such as seawater temperature and farm-numbers of fish. The model gives insight into factors that affect salmon lice abundance and contributing sources of infection. New findings in this study were that 66% of the expected salmon lice abundance was attributed to infection within farms, 28% was attributed to infection from neighbourhood farms and 6% to non-specified sources of infection. Furthermore, we present the relative risk of infection between neighbourhood farms as a function of seaway distance, which can be viewed as a between farm transmission kernel for salmon lice. The present modelling framework lays the foundation for development of future scenario simulation tools for examining the spread and abundance of salmon lice on farmed Salmonids under different control regimes.

  • sea lice as a density dependent constraint to Salmonid farming
    Proceedings of The Royal Society B: Biological Sciences, 2012
    Co-Authors: Peder A Jansen, Magne Aldrin, Anja B Kristoffersen, Hildegunn Viljugrein, Daniel Jimenez, Audun Stien
    Abstract:

    Fisheries catches worldwide have shown no increase over the last two decades, while aquaculture has been booming. To cover the demand for fish in the growing human population, continued high growth rates in aquaculture are needed. A potential constraint to such growth is infectious diseases, as disease transmission rates are expected to increase with increasing densities of farmed fish. Using an extensive dataset from all farms growing Salmonids along the Norwegian coast, we document that densities of farmed Salmonids surrounding individual farms have a strong effect on farm levels of parasitic sea lice and efforts to control sea lice infections. Furthermore, increased intervention efforts have been unsuccessful in controlling elevated infection levels in high Salmonid density areas in 2009–2010. Our results emphasize host density effects of farmed Salmonids on the population dynamics of sea lice and suggest that parasitic sea lice represent a potent negative feedback mechanism that may limit sustainable spatial densities of farmed Salmonids.

Ben F. Koop - One of the best experts on this subject based on the ideXlab platform.

  • the sex determining loci and sex chromosomes in the family Salmonidae
    Sexual Development, 2009
    Co-Authors: William S. Davidson, Kristian R. Von Schalburg, T K Huang, K Fujiki, Ben F. Koop
    Abstract:

    Salmonids are descended from a common ancestor that underwent an autotetraploidization event. After a whole genome duplication species could deal with sex determination by deleting one copy of SEX, the sex determining locus, or by recruiting a duplicated transcription factor to become a novel sex determining gene. It is not known which if any of these strategies Salmonids adopted, but it appears that they all have primarily a genetic mechanism of sex determination with male heterogamety. The sharing of sex-linked markers on the X and Y chromosomes and the difficulty in identifying Y-specific markers indicate that X and Y chromosomes in Salmonids have a large pseudoautosomal region and a small sex determining region. Linkage analyses suggest that either SEX differs in different lineages or else has remained the same and moved by transposition to different chromosomes. The identification of the sex chromosomes in Salmonid species has not resolved this issue. It is clear that Salmonids are at an early stage in sex chromosome differentiation and therefore provide a wonderful opportunity to study the evolution of sex determination. The availability of a reference Salmonid genome sequence would provide an important resource for research in this area.

  • Microarray analyses identify molecular biomarkers of Atlantic salmon macrophage and hematopoietic kidney response to Piscirickettsia salmonis infection
    Physiological genomics, 2004
    Co-Authors: Matthew L. Rise, Simon R. M. Jones, Gordon D. Brown, Kristian R. Von Schalburg, William S. Davidson, Ben F. Koop
    Abstract:

    Piscirickettsia salmonis is the intracellular bacterium that causes Salmonid rickettsial septicemia, an infectious disease that kills millions of farmed fish each year. The mechanisms used by P. sa...

Peter Andreas Heuch - One of the best experts on this subject based on the ideXlab platform.