Ongoing diversification of the global fish pathogen Piscirickettsia salmonis through genetic isolation and transposition bursts.

The management of bacterial pathogens remains a key challenge of aquaculture. The marine gammaproteobacterium Piscirickettsia salmonis is the etiological agent of piscirickettsiosis and causes multi-systemic infections in different salmon species, resulting in considerable mortality and substantial commercial losses. Here, we elucidate its global diversity, evolution, and selection during human interventions. Our comprehensive analysis of 73 closed, high quality genome sequences covered strains from major outbreaks and was supplemented by an analysis of all P. salmonis 16S rRNA gene sequences and metagenomic reads available in public databases. Genome comparison showed that Piscirickettsia comprises at least three distinct, genetically isolated species of which two showed evidence for continuing speciation. However, at least twice the number of species exist in marine fish or seawater. A hallmark of Piscirickettsia diversification is the unprecedented amount and diversity of transposases which are particularly active in subgroups undergoing rapid speciation and are key to the acquisition of novel genes and to pseudogenization. Several group-specific genes are involved in surface antigen synthesis and may explain the differences in virulence between strains. However, the frequent failure of antibiotic treatment of piscirickettsiosis outbreaks cannot be explained by horizontal acquisition of resistance genes which so far occurred only very rarely. Besides revealing a dynamic diversification of an important pathogen, our study also provides the data for improving its surveillance, predicting the emergence of novel lineages, and adapting aquaculture management, and thereby contributes towards the sustainability of salmon farming.

Effects of flavour variety on the intake and palatability of commercial feed in nursery pigs.

Sensory-specific satiety (SSS) could negatively affect pigs' feed intake, even when diets satisfy their nutritional requirements. We evaluated the short-term effects of SSS on feed intake and palatability. Thirty-two nursery pigs (tested in pairs) were exposed to short-term feeding trials for 6 days. In Trial 1, animals received for 90 min over three consecutive days three feeders: with different flavours (VAR); the same flavour (MON); or a mixture of the three flavours (MIX) in a 3 × 3 Latin square design. In Trial 2, with the same animals and different flavours, the three feeders were delivered successively (1 feeder every 30 min). In Trial 1, there was a day-by-diet interaction (F 4,36 = 2.98; p = 0.032), where the VAR diet was least consumed on the first day but most consumed subsequently. In Trial 2 a triple interaction between diet, day and delivery order modified pig's intake (F 12,15 = 3.33; p = 0.015), and consumption patterns (F 12,15 = 3.52; p = 0.012); where VAR diet presented the highest values in the last delivery order on the third experimental day. Flavour variety may decrease the effect of SSS, increasing feed intake and hedonic value in nursery pigs when there was a previous experience with those flavours.

Parameter study of decaying magnetohydrodynamic turbulence.

It is well known that helical magnetohydrodynamic (MHD) turbulence exhibits an inverse transfer of magnetic energy from small to large scales, which is related to the approximate conservation of magnetic helicity. Recently, several numerical investigations noticed the existence of an inverse energy transfer also in nonhelical MHD flows. We run a set of fully resolved direct numerical simulations and perform a wide parameter study of the inverse energy transfer and the decaying laws of helical and nonhelical MHD. Our numerical results show only a small inverse transfer of energy that grows as with increasing Prandtl number (Pm). This latter feature may have interesting consequences for cosmic magnetic field evolution. Additionally, we find that the decaying laws E∼t^{-p} are independent of the scale separation and depend solely on Pm and Re. In the helical case we measure a dependence of the form p_{b}≈0.6+14/Re. We also make a comparison between our results and previous literature and discuss the possible reason for the observed disagreements.

Proteomic and toxicological analysis of the response of dinoflagellate Alexandrium catenella to changes in NaNO3 concentration.

Dinoflagellates of the genus Alexandrium cause Harmful Algal Blooms (HABs) in coastal waters worldwide, damaging marine environments, aquaculture, and human health. They synthesize potent neurotoxic alkaloids known as PSTs (i.e., Paralytic Shellfish Toxins), the etiological agents of PSP (i.e., Paralytic Shellfish Poisoning). In recent decades, the eutrophication of coastal waters with inorganic nitrogen (e.g., nitrate, nitrite, and ammonia) has increased the frequency and scale of HABs. PSTs concentrations within Alexandrium cells can increase by up to 76% after a nitrogen enrichment event; however, the mechanisms that underlie their biosynthesis in dinoflagellates remains unclear. This study combines mass spectrometry, bioinformatics, and toxicology and investigates the expression profiles of PSTs in Alexandrium catenella grown in 0.4, 0.9 and 1.3 mM NaNO3. Pathway analysis of protein expression revealed that tRNA amino acylation, glycolysis, TCA cycle and pigment biosynthesis were upregulated in 0.4 mM and downregulated in 1.3 mM NaNO3 compared to those grown in 0.9 mM NaNO3. Conversely, ATP synthesis, photosynthesis and arginine biosynthesis were downregulated in 0.4 mM and upregulated in 1.3 mM NaNO3. Additionally, the expression of proteins involved in PST biosynthesis (sxtA, sxtG, sxtV, sxtW and sxtZ) and overall PST production like STX, NEO, C1, C2, GTX1-6 and dcGTX2 was higher at lower nitrate concentrations. Therefore, increased nitrogen concentrations increase protein synthesis, photosynthesis, and energy metabolism and decrease enzyme expression in PST biosynthesis and production. This research provides new clues about how the changes in the nitrate concentration can modulate different metabolic pathways and the expression of PST biosynthesis in toxigenic dinoflagellates.

Genomic and proteomic aspects of p57 protein from Renibacterium salmoninarum: Characteristics in virulence patterns.

Renibacterium salmoninarum is one of the oldest known fish bacterial pathogens. This Gram-positive bacterium is the causative agent of Bacterial Kidney Disease (BKD), a chronic infection that primarily infects salmonids at low temperatures. Externally, infected fish may show exophthalmos, skin blisters, ulcerations, and hemorrhages at the base of the fins and along the lateral line. Internally, the kidney, heart, spleen, and liver may show signs of inflammation. The best characterized virulence factor of R. salmoninarum is p57, a 57 kDa protein located on the bacterial cell surface and secreted into surrounding fish tissue. The p57 protein in fish is the main mediator in suppressing the immune system, reducing antibody production, and intervening in cytokine activity. In this review, we will discuss aspects such as single nucleotide polymorphisms (SNPs) that modify the DNA sequence, variants in the number of copies of MSA genes, physical-chemical properties of the signal peptides, and the limited iron conditions that can modify p57 expression and increase the virulence of R. salmoninarum.

Taquicardia sinusal post-COVID-19: patogenia, identificación y estratificación temprana / Post-COVID-19 sinus tachycardia: pathogenesis, identification and early stratification

Resumen La COVID-19 ha sido responsable de una alta morbimortalidad, la cual se caracteriza principalmente por síntomas respiratorios. Su ingreso a la célula está favorecido por la enzima convertidora de angiotensina tipo 2, presente en diversas células del organismo con efectos sistémicos. Los principales síntomas en el sistema cardiovascular son arritmias, insuficiencia cardiaca, choque cardiogénico, síndrome coronario agudo, bradicardia y taquicardia sinusal. Esta enfermedad tiene un pronóstico dependiente de factores genéticos y demográficos, con una evolución a la recuperación, la muerte o secuelas; a esto último diversos autores lo han descrito como «síndrome post-COVID-19¼. El compromiso cardiovascular se ve reflejado por la alta incidencia de taquicardia, detectada en el seguimiento de pacientes recuperados de la COVID-19 que refieren palpitaciones, y al explorar los signos vitales se comprueba el aumento en la frecuencia cardiaca. Sin embargo, su patogenia es desconocida, motivo por el que se realizó una revisión sistemática con el propósito de proponer hipótesis sobre los mecanismos fisiopatológicos para explicarla, algoritmos para la detección temprana y un tratamiento estratificado, para así contribuir en futuras investigaciones sobre esta asociación de taquicardia como daño cardiovascular posterior a la COVID-19, debido a la escasa evidencia científica sobre el tema.

Abstract COVID-19 has been responsible for a high morbi-mortality which is characterized by respiratory symptoms; its entrance to the cell is favored by angiotensin-converting enzyme 2, which is found in a variety of cells with systemic effects. The main symptoms in the cardiovascular system are: arrhythmia, heart failure, cardiogenic shock, acute coronary syndrome, bradycardia and sinus tachycardia. This disease has a prognosis that depends on genetic and demographic factors, with a progress whether to recovery, death or aftermath, then latter being described as "post-COVID-19 syndrome". Cardiovascular compromise is reflected by the high incidence in tachycardia detected in tracing of the recovered patients of COVID-19 that refer palpitations and that during exploration of vital signs can be ascertained by an increase in heart frequency. Nevertheless its pathogenic features are still unknown, for this reason a systematic review was made with the purpose of proposing hypotheses about the physiopathological mechanisms to explain it, algorithms for early detection and a stratified treatment, so it would contribute to future investigations about the association of tachycardia as cardiovascular damage after COVID-19, due to the lack of scientific evidence in this topic.

Health Status of Mytilus chilensis from Intensive Culture Areas in Chile Assessed by Molecular, Microbiological, and Histological Analyses.

Shellfish farming is a relevant economic activity in Chile, where the inner sea in Chiloé island concentrates 99% of the production of the mussel Mytilus chilensis. This area is characterized by the presence of numerous human activities, which could harm the quality of seawater. Additionally, the presence of potentially pathogenic microorganisms can influence the health status of mussels, which must be constantly monitored. To have a clear viewpoint of the health status of M. chilensis and to study its potential as a host species for exotic diseases, microbiological, molecular, and histological analyses were performed. This study was carried out in October 2018, where M. chilensis gut were studied for: presence of food-borne bacteria (Vibrio parahaemolyticus, Escherichia coli, Salmonella spp.), exotic bacteria ("Candidatus Xenohaliotis californiensis"), viruses (abalone and Ostreid herpes virus), and protozoa (Marteilia spp., Perkinsus spp. and Bonamia spp.). Additionally, 18S rDNA metabarcoding and histology analyses were included to have a complete evaluation of the health status of M. chilensis. Overall, despite the presence of risk factors, abnormal mortality rates were not reported during the monitoring period and the histological examination did not reveal significant lesions. Pathogens of mandatory notification to World Organization for Animal Health (OIE) and the Chilean National Fisheries and Aquaculture Service (SERNAPESCA) were not detected, which confirms that M. chilensis have a good health status, highlighting the importance of an integrated vision of different disciplines to ensure the sustainability of this important mussel industry in Chile.

Sucrose Inclusion in Gestating and Lactating Diets of Sows Modifies the Feeding Behavior of Post-Weaning Pigs for Sweet Solutions.

Pigs display an innate preference for sweet taste compounds such as sucrose. However, the influence of sucrose supplementation into maternal diets has not been examined in pigs. We tested the hypothesis that sucrose inclusion into sows' diets would modify the feeding behavior of post-weaning pigs for sweet and umami solutions. Twenty-two sows (85 days of gestation) were used. They randomly received a gestational and lactating diet with or without 50 g/kg of sucrose. Different sucrose and monosodium glutamate solutions were offered to the progeny to analyze different intake behavior measurements during nursery. Pigs born from treated sows presented a higher sucrose threshold than control animals (15 mM vs. 0.1 mM, p = 0.032) and displayed decreased sensory-motivated intake for this disaccharide (p < 0.023). Sucrose consumption decreased (p < 0.021) in pigs born from treated sows, as well as the consumption patterns for the less concentrated solutions (p < 0.014). The inclusion of sucrose into maternal diets (gestation and lactation) could modified pigs' feeding behavior after weaning when offered sweet solutions, which speaks against the practicality of this supplementation in pig production systems.

The Effect of Demonstrator Social Rank on the Attentiveness and Motivation of Pigs to Positively Interact with Their Human Caretakers.

In this study, we addressed the social attentiveness, as well as the phenomenon of social facilitation and inhibition in the context of a positive human-pig relationship. Specifically, we investigated whether the social rank of an experienced pig (termed "demonstrator") has an effect on the attentiveness of the remaining pen mates (N = 40) when they observe the demonstrator being gently handled by a stockperson from behind an acrylic panel. We found that pigs preferentially attended to dominant demonstrators rather than subordinate demonstrators during their gentle handling sessions with the stockperson. Additionally, we also examined whether the presence of a demonstrator pig of different social rank, who previously established a positive relationship with the stockperson in presence of conspecifics, affects the behavior and motivation of their pen mates to positively interact with the stockperson. To test for the effect of the presence and demonstrator's social rank on pen mate interactions with the stockperson, we evaluated the behavior of domestic pigs (N = 65) toward the stockperson using a human-approach test in their home-pen. Pigs showed a decrease in their motivation to positively interact with the stockperson when a socially dominant demonstrator was present, behaving similarly to animals receiving minimal human contact (control group). Overall, they exhibited a greater latency to physical contact, a lower acceptance of stroking, and spent more time looking at the stockperson compared to pigs exposed to subordinate demonstrators. Taken together, these findings expand our current understanding of pigs' cognition and social behavior, and the nature of social attention bias in farm animals. Our findings indicate that positive handling of previously selected subordinate demonstrators seems to be the best strategy to reduce the level of fear in large groups of pigs.

Development of a Multiplex PCR Assay for Genotyping the Fish Pathogen Piscirickettsia salmonis Through Comparative Genomics.

Piscirickettsia salmonis is a bacterial pathogen that severely impact the aquaculture in several countries as Canada, Scotland, Ireland, Norway, and Chile. It provokes Piscirickettsiosis outbreaks in the marine phase of salmonid farming, resulting in economic losses. The monophyletic genogroup LF-89 and a divergent genogroup EM-90 are responsible for the most severe Piscirickettsiosis outbreaks in Chile. Therefore, the development of methods for quick genotyping of P. salmonis genogroups in field samples is vital for veterinary diagnoses and understanding the population structure of this pathogen. The present study reports the development of a multiplex PCR for genotyping LF-89 and EM-90 genogroups based on comparative genomics of 73 fully sequenced P. salmonis genomes. The results revealed 2,322 sequences shared between 35 LF-89 genomes, 2,280 sequences in the core-genome of 38 EM-90 genomes, and 331 and 534 accessory coding sequences each genogroup, respectively. A total of 1,801 clusters of coding sequences were shared among all tested genomes of P. salmonis (LF-89 and EM-90), with 253 and 291 unique sequences for LF-89 and EM-90 genogroups, respectively. The Multiplex-1 prototype was chosen for reliable genotyping because of differences in annealing temperatures and respective reaction efficiencies. This method also identified the pathogen in field samples infected with LF-89 or EM-90 strains, which is not possible with other methods currently available. Finally, the genome-based multiplex PCR protocol presented in this study is a rapid and affordable alternative to classical sequencing of PCR products and analyzing the length of restriction fragment polymorphisms.

Idioventricular rhythm and shock after a honeybee sting / Ritmo idioventricular y shock después de un piquete de abeja

Abstract Objective: The objective of this study was to describe the case of a 19-year-old male presenting with bradycardia and hypotension after a honeybee sting making a review of the literature and pathophysiology of the cardiovascular and electrocardiogram (EKG) changes after a bee sting. Methods: The patient's airway was inspected and secured. Electrocardiogram with an idioventricular rhythm at 41' bpm. Oxygen was administered, an intravenous access was established, and the transcutaneous pacemaker leads were placed on the chest of the patient, then published guidelines management was induced. Results: The EKG showed idioventricular rhythm at a rate of 41 beats/min that resolved to a normal sinus rhythm after treatment. Conclusions: A full and prompt cardiovascular evaluation should be performed in all patients presenting to the emergency department after a bee sting, and published guidelines regarding the management of bradycardia and anaphylaxis should be followed to achieve successful outcomes.

Resumen Objetivo: Describir el caso de un paciente masculino de 19 años que presenta bradicardia e hipotensión después de una picadura de abeja haciendo una revisión de la literatura y fisiopatología de los cambios cardiovasculares y electrocardiográficos después de una picadura de abeja. Métodos: Se inspeccionó y aseguró la vía aérea del paciente. Un rastreo de ECG realizado al ingreso reveló ritmo idioventricular a una ritmo de 41 latidos por minuto. Se administró oxígeno, se estableció un acceso IV y se colocaron los cables del marcapasos transcutáneo en el tórax del paciente, luego se indujo el manejo de las guías publicadas. Resultados: El electrocardiograma mostró un ritmo idioventricular a una frecuencia de 41 latidos por minuto que se resolvió a un ritmo sinusal normal después del tratamiento. Conclusiones: Se debe realizar una evaluación cardiovascular completa y rápida en todos los pacientes que se presentan al departamento de emergencias después de una picadura de abeja, y se deben seguir las pautas publicadas sobre el manejo de la bradicardia y la anafilaxia para lograr resultados exitosos.

Idioventricular rhythm and shock after a honeybee sting.

OBJECTIVE: The objective of this study was to describe the case of a 19-year-old male presenting with bradycardia and hypotension after a honeybee sting making a review of the literature and pathophysiology of the cardiovascular and electrocardiogram (EKG) changes after a bee sting. METHODS: The patient's airway was inspected and secured. Electrocardiogram with an idioventricular rhythm at 41' bpm. Oxygen was administered, an intravenous access was established, and the transcutaneous pacemaker leads were placed on the chest of the patient, then published guidelines management was induced. RESULTS: The EKG showed idioventricular rhythm at a rate of 41 beats/min that resolved to a normal sinus rhythm after treatment. CONCLUSIONS: A full and prompt cardiovascular evaluation should be performed in all patients presenting to the emergency department after a bee sting, and published guidelines regarding the management of bradycardia and anaphylaxis should be followed to achieve successful outcomes.

OBJETIVO: Describir el caso de un paciente masculino de 19 años que presenta bradicardia e hipotensión después de una picadura de abeja haciendo una revisión de la literatura y fisiopatología de los cambios cardiovasculares y electrocardiográficos después de una picadura de abeja. MÉTODOS: Se inspeccionó y aseguró la vía aérea del paciente. Un rastreo de ECG realizado al ingreso reveló ritmo idioventricular a una ritmo de 41 latidos por minuto. Se administró oxígeno, se estableció un acceso IV y se colocaron los cables del marcapasos transcutáneo en el tórax del paciente, luego se indujo el manejo de las guías publicadas. RESULTADOS: El electrocardiograma mostró un ritmo idioventricular a una frecuencia de 41 latidos por minuto que se resolvió a un ritmo sinusal normal después del tratamiento. CONCLUSIONES: Se debe realizar una evaluación cardiovascular completa y rápida en todos los pacientes que se presentan al departamento de emergencias después de una picadura de abeja, y se deben seguir las pautas publicadas sobre el manejo de la bradicardia y la anafilaxia para lograr resultados exitosos.

Protein-Based Vaccine Protect Against Piscirickettsia salmonis in Atlantic Salmon (Salmo salar).

An effective and economical vaccine against the Piscirickettsia salmonis pathogen is needed for sustainable salmon farming and to reduce disease-related economic losses. Consequently, the aquaculture industry urgently needs to investigate efficient prophylactic measures. Three protein-based vaccine prototypes against Piscirickettsia salmonis were prepared from a highly pathogenic Chilean isolate. Only one vaccine effectively protected Atlantic salmon (Salmo salar), in correlation with the induction of Piscirickettsia-specific IgM antibodies and a high induction of transcripts encoding pro-inflammatory cytokines (i.e., Il-1ß and TNF-α). In addition, we studied the proteome fraction protein of P. salmonis strain Austral-005 using multidimensional protein identification technology. The analyzes identified 87 proteins of different subcellular origins, such as the cytoplasmic and membrane compartment, where many of them have virulence functions. The other two prototypes activated only the innate immune responses, but did not protect Salmo salar against P. salmonis. These results suggest that the knowledge of the formulation of vaccines based on P. salmonis proteins is useful as an effective therapy, this demonstrates the importance of the different research tools to improve the study of the different immune responses, resistance to diseases in the Atlantic salmon. We suggest that this vaccine can help prevent widespread infection by P. salmonis, in addition to being able to be used as a booster after a primary vaccine to maintain high levels of circulating protective antibodies, greatly helping to reduce the economic losses caused by the pathogen.

Do Domestic Pigs Acquire a Positive Perception of Humans through Observational Social Learning?

Farm animals can perceive humans positively by observing another animal being positively handled. This study evaluated whether pigs acquire a positive perception of humans after observing either a high or low socially ranked conspecific receiving gentle handling. Seventy-five 21-week-old pigs were housed in 15 nursery pens (five pigs/pen) and randomly assigned to one of three pen treatments: Dominant Demonstrator Group (DDG), Subordinate Demonstrator Group (SDG) and Control Group (CG). Pigs from DDG and SDG observed a high and low socially ranked conspecific ("demonstrator"), respectively, while the demonstrator received gentle stroking and a sucrose solution for 10 min, twice a day for 5 weeks. Control group pigs received minimal human contact. Following treatment, the behavior and heart rate variability of non-demonstrator pigs were evaluated in response to a stockperson in an open-field test. Pigs from the DDG and SDG contacted the stockperson sooner (p < 0.001), spent more time investigating the stockperson (p < 0.05), accepted more stroking (p < 0.001) and exhibited a lower low/high frequency ratio (p = 0.015) compared to the CG. No differences in learning between the pigs from the DDG and SDG were found. These results suggest that pigs can learn to perceive humans positively through observational social learning, regardless of the demonstrator conspecific's social rank.

Analysis of genes encoding for proteolytic enzymes and cytotoxic proteins as virulence factors of Piscirickettsia salmonis in SHK-1 cells.

Piscirickettsia salmonis is the causative agent of Piscirickettsiosis, a systemic disease generating high mortality rates in farmed salmon cultures of southern Chile. Proteolytic enzymes are important virulence factors since they play a key role in bacterial invasion and proliferation within the host. Bacteria growing in muscle tissues are known to secrete proteases, but no proteolytic enzymes have been described in P. salmonis to date. A battery of putative protease genes was found in the genomes and available strains of P. salmonis by bioinformatics analyses, and their identity was established through comparison with protease genes in databases. The transcript levels of five candidate genes were analysed by in vitro infection and qPCR. All strains were found to generate protease activity to varying degrees, and this was significantly increased when bacteria infected a salmon cell line. Gene expression of several types of proteases was also evidenced, with the highest levels corresponding to the type 1 secretion system (T1SS), which is also involved in the transport of haemolysin A, although transcripts with significant levels of peptidase M4 (thermolysin) and CLP protease were also found.

Corneal endothelial cell loss after trabeculectomy and phacoemulsification in one or two steps: a prospective study.

OBJECTIVE: The objective of this study was to analyse the results of the surgical treatment of coexisting cataract and glaucoma and its effects on corneal endothelial cell density (CECD). METHODS: We include two longitudinal prospective studies: one randomised that included 40 eyes with open angle glaucoma that received one- (n = 20) or two-step (n = 20) phacotrabeculectomy and another that included 20 eyes that received phacoemulsification. We assess the impact of surgery on different clinical variables and in particular in CECD using Confoscan 4™ confocal microscopy and semiautomatic counting methods. RESULTS: Phacoemulsification and phacotrabeculectomy, but not trabeculectomy, increase significantly best-corrected visual acuity and anterior chamber depth and trabeculectomy and one- or two-step phacotrabeculectomy decreased similarly the intraocular pressure. We document percentages of endothelial cell loss of 3.1%, 17.9%, 31.6% and 42.6% after trabeculectomy, phacoemulsification and one- or two-step phacotrabeculectomy, respectively. The coefficient of variation did not increase significantly after surgery but the percentage of hexagonality decreased significantly after phacoemulsification and after two-step phacotrabeculectomy. CONCLUSIONS: Trabeculectomy, phacoemulsification and phacotrabeculectomy are surgical techniques that cause morphological changes and decrease the densities of the corneal endothelial cells. Trabeculectomy produces lesser endothelial cell loss than phacoemulsification, and phacoemulsification lesser cell loss than phacotrabeculectomy. Two-step phacotrabeculectomy (trabeculectomy followed 3 months later by phacoemulsification) causes more cell loss than one-step phacotrabeculectomy, and this could be due to the cumulative effects of two separate surgical traumas or to a negative conditioning lesion effect of the first surgery. For the treatment of coexisting glaucoma and cataract, one-step phacotrabeculectomy is the treatment of choice.

Full recombinant flagellin B from Vibrio anguillarum (rFLA) and its recombinant D1 domain (rND1) promote a pro-inflammatory state and improve vaccination against P. salmonis in Atlantic salmon (S. salar).

Flagellin is the major component of the flagellum, and a ligand for Toll-like receptor 5. As reported, recombinant flagellin (rFLA) from Vibrio anguillarum and its D1 domain (rND1) are able to promote in vitro an upregulation of pro-inflammatory genes in gilthead seabream (Sparus aurata) and rainbow trout (Oncorhynchus mykiss) macrophages. This study evaluated the in vitro and in vivo stimulatory/adjuvant effect for rFLA and rND1 during P. salmonis vaccination in Atlantic salmon (Salmo salar). We demonstrated that rFLA and rND1 are molecules able to generate an acute upregulation of pro-inflammatory cytokines (IL-1ß, IL-8, IL-12ß), allowing the expression of genes associated with T-cell activation (IL-2, CD4, CD8ß), and differentiation (IFNγ, IL-4/13, T-bet, Eomes, GATA3), in a differential manner, tissue/time dependent way. Altogether, our results suggest that rFLA and rND1 are valid candidates to be used as an immuno-stimulant or adjuvants with existing vaccines in farmed salmon.

Exploring Anhedonia in Kennelled Dogs: Could Coping Styles Affect Hedonic Preferences for Sweet and Umami Flavours?

Kennelled dogs are at risk of suffering chronic stress due to long-term spatial, social and feeding restrictions. Chronic stress may decrease the dogs' capacity to feel pleasure when facing hedonic experiences, modifying their perception for palatable ingredients. However, different abilities to cope with environmental stressors could prevent the onset of anhedonia. Fourteen kennelled Beagle dogs were used to study the acceptability and preference for different dilute sucrose and monosodium glutamate (MSG) solutions. Coping style of animals was previously evaluated through a human approach test (HAT) and classified as close dogs (CD; proactive) or distant dogs (DD; reactive) according to whether or not they approached an unfamiliar human when a feeding opportunity was presented. Consumption results were analysed taking into account the sucrose/MSG concentrations, HAT (CD or DD), age, and weight of the animals. DD presented a lower intake of sucrose (p = 0.041) and MSG (p = 0.069) solutions compared with CD. However, DD exhibited a higher consumption of MSG than CD at its highest concentrations, supporting that their intake depends on solution palatability. Finally, DD did not prefer sucrose or MSG solutions over water at any dilute solution offered. Together, these results suggest that dogs that are categorized as reactive animals could diminish their ability to perceive dilute palatable solutions, reflecting depressive-like behaviours as anhedonia.

Biofilm Produced In Vitro by Piscirickettsia salmonis Generates Differential Cytotoxicity Levels and Expression Patterns of Immune Genes in the Atlantic Salmon Cell Line SHK-1.

Piscirickettsia salmonis is the causative agent of Piscirickettsiosis, an infectious disease with a high economic impact on the Chilean salmonid aquaculture industry. This bacterium produces biofilm as a potential resistance and persistence strategy against stressful environmental stimuli. However, the in vitro culture conditions that modulate biofilm formation as well as the effect of sessile bacteria on virulence and immune gene expression in host cells have not been described for P. salmonis. Therefore, this study aimed to analyze the biofilm formation by P. salmonis isolates under several NaCl and iron concentrations and to evaluate the virulence of planktonic and sessile bacteria, together with the immune gene expression induced by these bacterial conditions in an Atlantic salmon macrophage cell line. Our results showed that NaCl and Fe significantly increased biofilm production in the LF-89 type strain and EM-90-like isolates. Additionally, the planktonic EM-90 isolate and sessile LF-89 generated the highest virulence levels, associated with differential expression of il-1ß, il-8, nf-κb, and iκb-α genes in SHK-1 cells. These results suggest that there is no single virulence pattern or gene expression profile induced by the planktonic or sessile condition of P. salmonis, which are dependent on each strain and bacterial condition used.

Prolactin peptide (pPRL) induces anti-prolactin antibodies, ROS and cortisol but suppresses specific immune responses in rainbow trout.

Prolactin has several immune functions in fish however, the effects on innate and specific components of rainbow trout immunity are currently unknown. Therefore in this study, prolactin peptide (pPRL) injection in rainbow trout generated anti-PRL antibodies that were confirmed through Western blot assays of fish brain tissue extract. At the same time, this group of fish was immunized with a viral antigen (VP2) and the specific antibody titer generated by the rainbow trout was subsequently determined, as well as the sero-neutralizing capacity of the antibodies. Interestingly, this group of fish (pPRL-VP2) generated approximately 150% less antibodies compared with fish immunized only with the viral antigen (VP2), and pPRL-VP2 fish increased their cortisol level by 4 times compared to the control. Additionally, through qPCR assay, we determined that the pPRL-VP2 fish group decreased pro-inflammatory transcript expression, and the serum of these (pPRL-VP2) fish stimulated ROS production in untreated fish leukocytes, a phenomenon that was blocked by the pharmacological cortisol receptor inhibitor (RU486). Collectively, this is the first report that indicates that pPRL could modulate both components of immunity in rainbow trout.