Time filter

Source Type

Calbuco, Chile

Nunez-Acuna G.,University of Concepcion | Goncalves A.T.,University of Concepcion | Valenzuela-Munoz V.,University of Concepcion | Pino-Marambio J.,EWOS Innovation Chile | And 2 more authors.
Fish and Shellfish Immunology | Year: 2015

One of the most significant threats to the Chilean salmon aquaculture industry is the ectoparasitic sea louse Caligus rogercresseyi. To cope with sea lice infestations, functional diets have become an important component in strengthening the host immune response. The aim of this study was to evaluate molecular mechanisms activated through immunostimulation by in-feed plant-derived additives in Atlantic salmon infected with sea lice. Herein, a transcriptome-wide sequencing analysis was performed from skin and head kidney tissues, evidencing that the immune response genes were the most variable after the challenge, especially in the head kidney, while other genes involved in metabolism were highly expressed individuals fed with the immunostimulants. Interestingly, defensive enzymes such as Cytochrome p450 and serpins were down-regulated in infested individuals, especially in skin tissue. Additionally, MHC-I and MHC-II genes were differentially expressed after the incorporation of the in-feed additives, giving some cues about the protection mechanisms of plant-derived compound as immunostimulants for infested salmons. This is the first published study that evaluates the transcriptomic response of sea lice-infested Atlantic salmon fed with in-feed additives. © 2015 Elsevier Ltd.

Nunez-Acuna G.,University of Concepcion | Valenzuela-Munoz V.,University of Concepcion | Marambio J.P.,EWOS Innovation Chile | Wadsworth S.,Innovation Norway | Gallardo-Escarate C.,University of Concepcion
Experimental Parasitology | Year: 2014

Although various elements of the olfactory system have been elucidated in insects, it remains practically unstudied in crustaceans at a molecular level. Among crustaceans, some species are classified as ectoparasites that impact the finfish aquaculture industry. Thus, there is an urgent need to identify and comprehend the signaling pathways used by these in host recognition. The present study, through RNA-seq and qPCR analyses, found novel transcripts involved in the olfactory system of Caligus rogercresseyi, in addition to the transcriptomic patterns expressed during different stages of salmon lice development. From a transcriptomic library generated by Illumina sequencing, contigs that annotated for ionotropic receptors and other genes implicated in the olfactory system were identified and extracted. Full length mRNA was obtained for the ionotropic glutamate receptor 25, which had 3923. bp, and for the glutamate receptor ionotropic kainate 2, which had 2737. bp. Furthermore, two other transcripts identified as glutamate receptor, ionotropic kainate 2-like were found. In silico analysis was performed for the transcription expression from different stages of development in C. rogercresseyi, and clusters according to RPKM values were constructed. Gene transcription data were validated through qPCR assays in ionotropic receptors, and showed an expression of glutamate receptor 25 associated with the copepodid stage whereas adults, especially male adults, were associated with the kainate 2 and kainate 2-like transcripts. Additionally, gene transcription analysis of the ionotropic receptors showed an overexpression in response to the presence of masking compounds and immunostimulant in salmon diets. This response correlated to a reduction in sea lice infection following in vivo challenge. Diets with masking compounds showed a decrease of lice infestation of up to 25%. This work contributes to the available knowledge on chemosensory systems in this ectoparasite, providing novel elements towards understanding the host-finding process of the salmon louse C. rogercresseyi. © 2014 Elsevier Inc.

Oliver C.,Austral University of Chile | Valenzuela K.,Austral University of Chile | Silva H.,Austral University of Chile | Haro R.E.,Austral University of Chile | And 12 more authors.
Journal of Applied Microbiology | Year: 2015

Aims: To produce and characterize egg yolk immunoglobulin (IgY) against the fish intracellular pathogen Piscirickettsia salmonis as well as to evaluate the antibacterial activity of IgY in vitro and the availability in the serum of fish immunized orally. Methods and Results: Specific IgY was produced by immunizing hens with P. salmonis proteins. The IgY was obtained from egg yolks using the ammonium sulphate precipitation method and it was characterized by SDS-PAGE, Western-blot and ELISA, demonstrating that anti-P. salmonis IgY strongly reacted specifically against P. salmonis proteins. In an in vitro neutralization assay, IgY inhibited the growth of P. salmonis in liquid medium at concentrations ranging from 128 to 256 μg ml-1 in a dose-dependent manner. Interestingly, IgY against P. salmonis also generates a strong protective effect on the infection of P. salmonis in salmon head kidney-1 cells. In addition, the bacteriostatic function of IgY appears to result possibly from agglutination by the interaction of IgY with surface components of the pathogen. Finally, to confirm this IgY as an alternative for salmonid treatment, Atlantic salmon (Salmo salar) specimens were orally inoculated with IgY. The analysis of the sera demonstrates that IgY was effectively transported by fish intestine and that this immunoglobulins maintains its properties and recognizes several proteins of P. salmonis up to 12 h after inoculation of IgY against P. salmonis. Conclusions: Specific IgY effectively inhibited the growth of P. salmonis and this immunoglobulin can be released in the Atlantic salmon sera when administered orally to fish. Significance and Impact of the Study: We propose that this specific IgY against this fastidious micro-organism could be a useful strategy for the treatment of piscirickettsiosis. © 2015 The Society for Applied Microbiology.

Oelckers K.,EWOS Innovation Chile | Vike S.,Cermaq ASA | Duesund H.,Cermaq ASA | Gonzalez J.,EWOS Innovation Chile | And 2 more authors.
Aquaculture | Year: 2014

The sea louse Caligus rogercresseyi is the most serious ectoparasite on farmed salmonids in Chile, mainly affecting Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss). In 2007 the highest infestation ever recorded for this sea louse struck the aquaculture industry. In the same year a serious epizootic due to the Infectious Salmon Anaemia (ISA) virus (Isavirus, family Orthomyxoviridae) also occurred.This study shows that C. rogercresseyi is capable of being a mechanical vector for ISA virus. The findings indicate that even after 48. hours away from its host C. rogercresseyi can still transmit ISA virus to naïve Atlantic salmon, which was confirmed by sequencing of the virus. Both the amount and prevalence of ISA virus RNA were decreasing the longer C. rogercresseyi was away from its host. This indicates that ISA virus is not replicating in the lice and hence, it is not likely that C. rogercresseyi could be a biological vector.ISA virus positive Caligus sp. nauplius larvae or copepodids were neither detected inside nor outside the Atlantic salmon farming cage experiencing ISA outbreaks. Nor was it possible to detect ISA virus RNA in nauplius larvae or copepodids retained in the lab, even if they were the offspring of ISA virus positive C. rogercresseyi population. This indicates that ISA virus is not vertically transmitted from adult C. rogercresseyi to nauplii. Based on these results it is not very likely that Caligus sp. nauplius larvae or copepodids are vectors for ISA viruses.For the salmonid industry this means that a co-infection with ISA virus and C. rogercresseyi increases the risk of transmission of ISA virus within the site and also to other sites in the same hydrographical area. © 2013 Elsevier B.V.

Nunez-Acuna G.,University of Concepcion | Vera-Bizama F.,University of Concepcion | Boltana S.,University of Concepcion | Hawes C.,EWOS Innovation Chile | And 3 more authors.
Aquaculture | Year: 2016

Recently, a group of chemosensory receptors from the ionotropic receptor family wasmolecularly characterized in the sea louse Caligus rogercresseyi. Nonetheless, understanding the physiological functions of these genes during the sea lice infestation process remains pending. Herein, the aim of this study was to determine the transcriptional modulation of ionotropic receptor genes from C. rogercresseyi while infesting Salmo salar and Oncorhynchus kisutch, aswell as to evaluate the effects in-feed additives on sea lice transcriptome. The results revealed significant differences in parasitic load between control diet and the anti-attachment or immunostimulant diet groups. Moreover, therewere notable differences in the gene transcription profiles of ionotropic receptors in each group. Under a normal commercial diet, therewas a general trend towards higher transcription levels in sea lice infesting S. salar, especially at seven days post-infection. This same tendency occurred in sea lice infesting fish fed an immunostimulant diet, but an opposite trendwas found in sea lice infesting fish fed with anti-attachment masking compounds. In this case, sea lice infesting O. kisutch expressed higher ionotropic receptor levels at seven days post-infection. This study advances the knowledge related to ionotropic receptors and the involvement of these in host-parasite interactions, especially in relation to semiochemical signaling detection. Statement of relevance: This is a contribution to sea lice control in salmon farms. © 2015 Elsevier B.V.

Discover hidden collaborations