Subjective machines: Probabilistic risk assessment based on deep learning of soft information.

For several years machine learning methods have been proposed for risk classification. While machine learning methods have also been used for failure diagnosis and condition monitoring, to the best of our knowledge, these methods have not been used for probabilistic risk assessment. Probabilistic risk assessment is a subjective process. The problem of how well machine learning methods can emulate expert judgments is challenging. Expert judgments are based on mental shortcuts, heuristics, which are susceptible to biases. This paper presents a process for developing natural language-based probabilistic risk assessment models, applying deep learning algorithms to emulate experts' quantified risk estimates. This allows the risk analyst to obtain an a priori risk assessment when there is limited information in the form of text and numeric data. Universal sentence embedding (USE) with gradient boosting regression (GBR) trees trained over limited structured data presented the most promising results. When we apply these models' outputs to generate survival distributions for autonomous systems' likelihood of loss with distance, we observe that for open water and ice shelf operating environments, the differences between the survival distributions generated by the machine learning algorithm and those generated by the experts are not statistically significant.

Estimates of Effective Population Size in Commercial and Hatchery Strains of Coho Salmon (Oncorhynchus kisutch (Walbaum, 1792)).

Understanding the genetic status of aquaculture strains is essential for developing management guidelines aimed at sustaining the rates of genetic gain for economically important traits, as well as securing populations that will be robust to climate change. Coho salmon was the first salmonid introduced to Chile for commercial purposes and now comprises an essential component of the country's aquaculture industry. Several events, such as admixture, genetic bottlenecks, and rapid domestication, appear to be determinants in shaping the genome of commercial strains representing this species. To determine the impact of such events on the genetic diversity of these strains, we sought to estimate the effective population size (Ne) of several of these strains using genome-wide approaches. We compared these estimates to commercial strains from North America and Japan, as well as a hatchery strain used for supportive breeding of wild populations. The estimates of Ne were based on a method robust to assumptions about changes in population history, and ranged from low (Ne = 34) to relatively high (Ne = 80) in the Chilean strains. These estimates were higher than those obtained from the commercial North American strain but lower than those observed in the hatchery population and the Japanese strain (with Ne over 150). Our results suggest that some populations require measures to control the rates of inbreeding, possibly by using genomic information and incorporating new genetic material to ensure the long-term sustainability of these populations.

First genome sequence of Chilean Brucella canis SCL strain provides insights on the epidemiology and virulence factors, explaining differences between geographical origins

BACKGROUND: Brucella canis is the etiological agent of canine brucellosis, a worldwide neglected zoonosis that constitutes one of the major infectious causes of infertility and reproductive failure in dogs. Although genomic information available for this pathogen has increased in recent years, here we report the first genome sequencing of a B. canis strain in Chile, and the differences in virulence genes with other B. canis strains. RESULTS: Genome assembly produced a total length of 3,289,216 bp, N50 of 95,163 and GC% of 57.27, organized in 54 contigs in chromosome I, and 21 contigs in chromosome II. The genome annotation identified a total of 1981 CDS, 3 rRNA and 36 tRNA in chromosome I, and 1113 CDS and 10 tRNA in chromosome II. There is little variation between the different strains and the SCL isolate. Phylogenetic analysis showed that the Chilean SCL strain is closely related to B. canis and B. suis strains. Small differences were found when compared to the Serbian isolate, but all strains shared the same recent common ancestor. Finally, changes in the sequence of some virulence factors showed that the SCL strain is similar to other South American B. canis strains. CONCLUSIONS: This work sequenced and characterized the complete genome of B. canis strain SCL, evidencing the complete presence of all the genes of the virB operon, and minor changes in outer membrane proteins and in the urease operon. Our data suggest that B. canis was introduced from North America and then spread throughout the South American continent.

Shear bond strength evaluation of metallic brackets bonded to a CAD/CAM PMMA material compared to traditional prosthetic temporary materials: an in vitro study.

INTRODUCTION: Orthodontic treatment for adults is currently increasing, and therefore the need to bond brackets to restorations and temporary crowns. The use of CAD/CAM PMMA provisional restorations for orthodontic purposes have not yet been described, and there is currently insufficient information regarding the strength of bracket adhesion. OBJECTIVE: This study aimed at evaluating the effects of thermocycling (TC) and surface treatment on shear bond strength (SBS) of brackets to different provisional materials. METHODS: Forty specimens were made from each material [PMMA (Telio Lab), bis-acryl (Telio CS C&B), and PMMA CAD/CAM (Telio CAD)], sandpapered, and divided according to surface treatment (pumiced or sandblasted) and TC (half of the samples = 1,000 cycles, 5°C/55°C water baths) (n = 10/group). Stainless-steel brackets were bonded to the specimens (using Transbond XT), and SBS testing was performed. Data were analyzed by three-way ANOVA and LSD post-hoc tests (α = 0.05). Failure types were classified with adhesive remnant index (ARI) scores. RESULTS: SBS values ranged from 1.5 to 14.9 MPa. Sandblasted bis-acryl and sandblasted auto-curing PMMA groups presented similar values (p> 0.05), higher than the CAD/CAM material (p< 0.05), with or without TC. When thermocycled, pumiced bis-acryl showed higher SBS than pumiced acrylic (p= 0.005) and CAD/CAM materials (p= 0.000), with statistical difference (p= 0.009). TC showed negative effect (p< 0.05) for sandblasted bis-acryl and pumiced acrylic groups. ARI predominant score was mostly zero (0) for CAD/CAM, 1 and 2 for bis-acryl, and 1 for acrylic groups. CONCLUSION: In general, bis-acryl material showed the highest SBS values, followed by acrylic and CAD/CAM materials, which showed SBS values lower than an optimum strength for bonding brackets.

Shear bond strength evaluation of metallic brackets bonded to a CAD/CAM PMMA material compared to traditional prosthetic temporary materials: an in vitro study

ABSTRACT Introduction: Orthodontic treatment for adults is currently increasing, and therefore the need to bond brackets to restorations and temporary crowns. The use of CAD/CAM PMMA provisional restorations for orthodontic purposes have not yet been described, and there is currently insufficient information regarding the strength of bracket adhesion. Objective: This study aimed at evaluating the effects of thermocycling (TC) and surface treatment on shear bond strength (SBS) of brackets to different provisional materials. Methods: Forty specimens were made from each material [PMMA (Telio Lab), bis-acryl (Telio CS C&B), and PMMA CAD/CAM (Telio CAD)], sandpapered, and divided according to surface treatment (pumiced or sandblasted) and TC (half of the samples = 1,000 cycles, 5°C/55°C water baths) (n = 10/group). Stainless-steel brackets were bonded to the specimens (using Transbond XT), and SBS testing was performed. Data were analyzed by three-way ANOVA and LSD post-hoc tests (α = 0.05). Failure types were classified with adhesive remnant index (ARI) scores. Results: SBS values ranged from 1.5 to 14.9 MPa. Sandblasted bis-acryl and sandblasted auto-curing PMMA groups presented similar values (p> 0.05), higher than the CAD/CAM material (p< 0.05), with or without TC. When thermocycled, pumiced bis-acryl showed higher SBS than pumiced acrylic (p= 0.005) and CAD/CAM materials (p= 0.000), with statistical difference (p= 0.009). TC showed negative effect (p< 0.05) for sandblasted bis-acryl and pumiced acrylic groups. ARI predominant score was mostly zero (0) for CAD/CAM, 1 and 2 for bis-acryl, and 1 for acrylic groups. Conclusion: In general, bis-acryl material showed the highest SBS values, followed by acrylic and CAD/CAM materials, which showed SBS values lower than an optimum strength for bonding brackets.

RESUMO Introdução: Atualmente, a demanda por tratamento ortodôntico em adultos tem aumentado. Consequentemente, também tem aumentado a necessidade de se colar braquetes em restaurações e coroas provisórias. O uso de restaurações provisórias de PMMA CAD/CAM com finalidade ortodôntica ainda não foi descrito e, até a presente data, não há informação suficiente sobre a resistência da colagem dos braquetes a esse tipo de material. Objetivo: O presente estudo teve como objetivo avaliar os efeitos da termociclagem (TC) e do tratamento de superfície sobre a resistência da colagem ao cisalhamento (RC) de braquetes colados em diferentes materiais provisórios. Métodos: Quarenta espécimes foram confeccionados de cada material: resina acrílica PMMA (Telio Lab), resina bisacrílica (Telio CS C&B), e PMMA CAD/CAM (Telio CAD). Em seguida, foram lixados e divididos de acordo com o tratamento de superfície (polidos ou jateados) e TC (metade da amostra - 1.000 ciclos de imersão em água a 5°C e 55°C) (n = 10/grupo). Braquetes de aço inoxidável foram colados aos espécimes (utilizando Transbond XT) e realizou-se o teste de RC. As informações foram analisadas por meio dos testes ANOVA de três vias e post-hoc LSD (α?#8197;= 0,05). Os tipos de falha foram classificados de acordo com os escores do índice de adesivo remanescente (ARI). Resultados: Os valores de RC variaram de 1,5 a 14,9 MPa. Os grupos de resina bisacrílica jateada e de PMMA autopolimerizável jateado apresentaram valores semelhantes (p> 0,05), superiores ao do material CAD/CAM (p< 0,05) com ou sem TC. Quando submetido à TC, o grupo de resina bisacrílica polida apresentou resistência ao cisalhamento maior do que os grupos de resina acrílica polida (p= 0,005) e do material CAD/CAM (p= 0,000), com diferença estatística (p= 0,009). A TC apresentou efeito negativo (p< 0,05) para os grupos de resina bisacrílica jateada e de resina acrílica polida. O escore ARI = 0 foi predominante para o grupo CAD/CAM; os escores 1 e 2, para o grupo resina bisacrílica; e o escore 1, para o grupo resina acrílica. Conclusão: De forma geral, a resina bisacrílica apresentou os maiores valores de RC, seguida da resina acrílica e do material CAD/CAM, que apresentaram valores de RC inferiores à força recomendada para colagem de braquetes.

A novel sequencing-based vaginal health assay combining self-sampling, HPV detection and genotyping, STI detection, and vaginal microbiome analysis.

The composition of the vaginal microbiome, including both the presence of pathogens involved in sexually transmitted infections (STI) as well as commensal microbiota, has been shown to have important associations for a woman's reproductive and general health. Currently, healthcare providers cannot offer comprehensive vaginal microbiome screening, but are limited to the detection of individual pathogens, such as high-risk human papillomavirus (hrHPV), the predominant cause of cervical cancer. There is no single test on the market that combines HPV, STI, and microbiome screening. Here, we describe a novel inclusive vaginal health assay that combines self-sampling with sequencing-based HPV detection and genotyping, vaginal microbiome analysis, and STI-associated pathogen detection. The assay includes genotyping and detection of 14 hrHPV types, 5 low-risk HPV types (lrHPV), as well as the relative abundance of 31 bacterial taxa of clinical importance, including Lactobacillus, Sneathia, Gardnerella, and 3 pathogens involved in STI, with high sensitivity, specificity, and reproducibility. For each of these taxa, reference ranges were determined in a group of 50 self-reported healthy women. The HPV sequencing portion of the test was evaluated against the digene High-Risk HPV HC2 DNA test. For hrHPV genotyping, agreement was 95.3% with a kappa of 0.804 (601 samples); after removal of samples in which the digene hrHPV probe showed cross-reactivity with lrHPV types, the sensitivity and specificity of the hrHPV genotyping assay were 94.5% and 96.6%, respectively, with a kappa of 0.841. For lrHPV genotyping, agreement was 93.9% with a kappa of 0.788 (148 samples), while sensitivity and specificity were 100% and 92.9%, respectively. This novel assay could be used to complement conventional cervical cancer screening, because its self-sampling format can expand access among women who would otherwise not participate, and because of its additional information about the composition of the vaginal microbiome and the presence of pathogens.

Development of a Bicistronic Vector for the Expression of a CRISPR/Cas9-mCherry System in Fish Cell Lines.

The clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system has been widely used in animals as an efficient genome editing tool. In fish cells, the technique has been difficult to implement due to the lack of proper vectors that use active promoters to drive the expression of both small guide RNA (sgRNA) and the S. pyogenes Cas9 (spCas9) protein within a single expression platform. Until now, fish cells have been modified using co-transfection of the mRNA of both the sgRNA and the spCas9. In the present study, we describe the optimization of a new vector for the expression of a CRISPR/Cas9 system, designed to edit the genome of fish cell lines, that combines a gene reporter (mCherry), sgRNA, and spCas9 in a single vector, facilitating the study of the efficiency of piscine and non-piscine promoters. A cassette containing the zebrafish U6 RNA III polymerase (U6ZF) promoter was used for the expression of the sgRNA. The new plasmid displayed the expression of spCas9, mCherry, and sgRNA in CHSE/F fish cells. The results demonstrate the functionality of the mammalian promoter and the U6ZF promoter in fish cell lines. This is the first approach aimed at developing a unified genome editing system in fish cells using bicistronic vectors, thus creating a powerful biotechnological platform to study gene function.

Susceptibilidad de Cepas de Candida Oral a Extracto Etanólico del Propóleo Chileno de Olmué / Susceptibility of Oral Candida Strains to Ethanol Extract of Chilean Propolis of Olmué

RESUMEN: La infección por Candida albicans en la mucosa oral es conocida como Candidiasis oral (CO) y se diagnostica por el reconocimiento de cambios clínicos y la presencia de pseudohifas, hifas o levaduras en muestras obtenidas por citología exfoliativa o biopsia. Los agentes farmacológicos tópicos clásicos para el tratamiento de CO son Nistatina y Miconazol. Sin embargo, a pesar de las distintas terapias contra CO, existen formas de Candida resistentes al tratamiento convencional. El objetivo de este estudio fue determinar la susceptibilidad in vitro de Candida spp. a un extracto etanólico de propóleo de Olmué. Se realizó un estudio experimental descriptivo in vitro en donde se evaluó el efecto que presenta el uso de extracto etanólico de propóleo como antifúngico sobre cepas de Candida spp. obtenidas de la cavidad oral (mucosa palatina) de 31 individuos, con candidiasis oral diagnosticados con estomatitis subprotésica. El propóleo chileno utilizado fue obtenido de la zona geográfica de Olmué, quinta región. Se encontró que el 100 % de las muestras en rangos de concentración de propóleo de 0,1 µg/mL y 1,6 µg/mL presentaron un grado de inhibición en el crecimiento de Candida Oral y por otra parte el extracto etanólico de propóleo que generó inhibición en la mayor cantidad de muestras fue al 0,4 µg/mL (41,94 % de las muestras) y en segundo lugar la concentración al 0,2 µg/mL (35 % de las muestras). Se concluyó que el extracto etanólico de propóleo chileno obtenido de la zona de Olmué presenta la capacidad de inhibir el crecimiento de Candida spp. en agar Sabouraud in vitro de forma dosis dependiente.

ABSTRACT: Fungal (or yeast) infections; mycoses, occurring in the oral mucous membranes, of Candida species (mostly C. albicans, a normal component of the oral microbiota), also known as oral thrush or oral candidiasis (OC), can be diagnosed via the recognition of clinical changes and the presence of pseudohyphae, hyphae or yeasts in samples obtained by exfoliative cytology and/or biopsy. Topical pharmacological preparations and drugs such as Nystatin and Miconazole are used in the treatment of CO. However, there are forms of Candida with resistance to such conventional treatment approaches. Therefore, the aim of this study is to determine the in vitro susceptibility of Candida spp.; an ethanolic extract of propolis from Olmué. Hence, an experimental in vitro descriptive study was carried out in which the effect of an ethanolic extract of propolis used as antifungal on strains of Candida spp. obtained from the oral cavity (palatine mucosa) of 31 individuals, diagnosed with OC (subdenture stomatitis) is determined. Natural propolis was obtained from the Olmué area, in the 5th region of Chile. It was found that 100 % of the samples with propolis concentration ranging from 0.1 mg / mL to 1.6 mg / mL presented a degree of inhibition in the growth of OC. On the other hand, the ethanolic extract of propolis that generated inhibition in the largestnumber of samples was 0.4 mg / mL (41.94 % of the samples) followed by the concentration of 0.2 mg / mL (35 % of the samples). Therefore, it can be concluded that the ethanolic extract of Chilean propolis obtained from the Olmué area has the ability to inhibit the growth of Candida spp. in vitro in a dosage-dependent manner.

In-vitro comparative study of the use of 2 % chlorhexidine on microtensile bond strength of different dentin adhesives: a 6 months evaluation / Estudio comparativo in vitro del uso de clorhexidina al 2 % sobre la resistencia de unión microtensil de diferentes adhesivos dentinarios: una evaluación de 6 meses

The aim of this study was to evaluate the effect of chlorhexidine (CHX) dentin treatment on microtensile bond strength (µTBS) of adhesive systems in different storage times. Occlusal enamel was removed from ninety third-molars and flat surfaces of middle dentin were exposed. Teeth were randomly divided in 6 groups according to adhesive system (etch-and-rinse : Adper Scotchbond 1XT - ASB ; self-etch: Adper Prompt L-Pop ­ APP; and universal: Single Bond Universal - SBU) and chlorhexidine (CHX) dentin treatment (2 % CHX application for 20 s prior Primer). After resin composite build up, teeth were sectioned to obtain beam specimens and divided in 3 subgroups (n=5): 72h, 3 and 6 months storage times. After the storage times, teeth were tested in tension until failure (0.5 mm/min). SEM was performed to observe hybrid layer of adhesive systems. Data were analyzed using one-way ANOVA and Tukey tests. At 72 h, all equivalent groups (same adhesive system, different dentin treatments) maintained their µTBS when compared CHX-treatment. At 3 and 6 months, non-treated CHX groups showed less µTBS than CHX-treated ones. Six months storage time did not significantly decrease µTBS, except for G2-ASB. The effect of CHX on dentin µTBS depends on storage times and adhesive systems. While immediate µTBS was not affected by CHX treatment, CHX improved dentin µTBS after 3 and 6 months.

El objetivo de este estudio fue evaluar el efecto del tratamiento con clorhexidina (CHX) de la dentina sobre la resistencia de la unión microtensil (mTBS) de los sistemas adhesivos en diferentes tiempos de almacenamiento. Se retiró el esmalte oclusal de noventa terceros molares y se expusieron superficies planas de la dentina media. Los dientes se dividieron al azar en 6 grupos de acuerdo con el sistema adhesivo (con grabado ácido: Adper Scotchbond 1XT-ASB, auto-grabado: Adper Prompt L-Pop-APP y universal: Single Bond Universal- SBU) y el tratamiento de la dentina con clorhexidina (CHX) (aplicación de CHX al 2 % 20 s antes del Primer). Después de la aplicación de la resina compuesta, los dientes fueron seccionados para obtener muestras en forma de barras y divididos en 3 subgrupos (n = 5) con tiempos de almacenamiento de 72 h, 3 y 6 meses. Después de los tiempos de almacenamiento, los dientes se sometieron a tensión hasta la fractura (0,5 mm / min). SEM se realizó para observar la capa híbrida de sistemas adhesivos. Los datos se analizaron mediante ANOVA unidireccional y pruebas de Tukey. A las 72 h, todos los grupos equivalentes (el mismo sistema adhesivo, diferentes tratamientos de dentina) mantuvieron su mTBS cuando se comparó el tratamiento CHX. A los 3 y 6 meses, los grupos CHX no tratados mostraron menos mTBS que los tratados con CHX. Seis meses de tiempo de almacenamiento no disminuyó significativamente el mTBS, excepto para el G2-ASB. El efecto de CHX sobre la dentina mTBS depende del tiempo de almacenamiento y de los sistemas adhesivos. Mientras que el mTBS inmediato no se vio afectado por el tratamiento con CHX, CHX mejoró la mTBS a dentina después de 3 y 6 meses.

Effect of 2 % chlorhexidine on dentin shear bond strength of different adhesive systems: a 6 months evaluation / Efecto de la clorhexidina al 2 % sobre la resistencia al cizallamiento de diferentes sistemas adhesivos: una evaluación de 6 meses

This study evaluated the effect of chlorhexidine dentin treatment on shear bond strength (SBS) of adhesive systems after different storages. The work included 144 third molars that had their dentin exposed and were divided in 6 groups: G1 (ASB+CHX: Adper Scotchbond 1XT + chlorhexidine 2 % prior Primer); G2(ASB); G3 (APP+CHX: Adper Prompt L-Pop + CHX); G4(APP); G5 (SBU+CHX: Single Bond Universal + CHX); and G6(SBU). Resin build-up was performed and teeth were subdivided regarding storage times (n=8): 72 h, 3 and 6 months. Next, SBS test was performed. At 72 hours, all equivalent groups (same adhesive system, different dentin treatment) showed no significant difference in SBS (P.05). Self-etch adhesive groups (with or without CHX) presented lower SBS compared to other systems (P.05). After 3 and 6 months, all CHX-treated groups presented significantly higher SBS compared to equivalent non-treated groups (P.05). For both storage times, Single Bond Universal presented the highest SBS values within the same dentin treatment (P.05), while Adper Scotchbond and Adper Prompt-L-Pop were not significantly different among them, also within the same dentin treatments [3 months (with CHX: P=.966; without: P=.958) and 6 months (with CHX: P =.887; without: P=.990)]. CHX Dentin disinfection is indicated for all classes of adhesives studied.

Este estudio evaluó el efecto del tratamiento de la dentina con clorhexidina sobre la resistencia al cizallamiento (SBS) de sistemas adhesivos después de diferentes almacenamientos. Se removió el esmalte oclusal a 144 terceros molares y se dejó su dentina media expuesta, posteriormente se dividieron al azar en 6 grupos: G1 (ASB + CHX: Adper Scotchbond 1XT + clorhexidina 2 % antes del Primer); G2 (ASB); G3 (APP + CHX: L-Pop + CHX de Adper); G4 (APP); G5 (SBU + CHX: Single Bond Universal + CHX); y G6 (SBU). Se realizó la aplicación de la resina compuesta y se subdividieron los grupos con respecto a los tiempos de almacenamiento (n = 8): 72h, 3 y 6 meses. A continuación, se realizó la prueba SBS. A las 72 horas, todos los grupos equivalentes (el mismo sistema adhesivo, diferentes tratamientos de dentina) no mostraron diferencias significativas en los valores de SBS (P.05). Los grupos de adhesivo de auto-grabado (con o sin CHX) presentaron valores de SBS más bajos en comparación con otros sistemas (P.05). Después de 3 y 6 meses, todos los grupos tratados con CHX presentaron valores de SBS significativamente mayores en comparación con los grupos no tratados equivalentes (P.05). Para ambos tiempos de almacenamiento, Single Bond Universal presentó los valores de SBS más altos dentro del mismo tratamiento dentinario (P.05), mientras que el Adper Scotchbond y el Adper Prompt-L-Pop no fueron significativamente diferentes entre ellos, también dentro de los mismos tratamientos dentinarios 3 meses (con CHX: P = .966, sin: P = .958) y 6 meses (con CHX: P = .887; sin: P = .990). La desinfección de la dentina con CHX está indicada para todas las clases de adhesivos estudiados.

Fibroma odontogénico periférico: reporte de un caso / Peripheral odontogenic fibroma: case report

El Fibroma Odontogénico Periférico fue definido por la OMS en el año 2005 como una neoplasia benigna rara constituida por tejido fibroso maduro y una cantidad variable de epitelio odontogénico inactivo. Dada su presentación clínica, localización y baja prevalencia suele ser mal diagnosticado como una lesión reaccional. Se presenta un caso clínico de fibroma odontogénico periférico tratado mediante remoción quirúrgica y se realiza una revisión de la bibliografía respecto a la patología con el propósito de esclarecer algunos aspectos de esta lesión, además de incluirla dentro de los posibles diagnósticos diferenciales de lesiones reaccionales gingivales. El objetivo del siguiente artículo es presentar un caso clínico de FOP tratado mediante remoción quirúrgica y aportar en el diagnóstico diferencial de las lesiones reaccionales gingivales.

Peripheral odontogenic fibroma was described by the World Health Organization (WHO) in 2005, as a rare benign tumor containing mature fibrous connective tissue with a varying amount of inactive odontogenic epithelium. Though its clinical presentation, localization and low prevalence, it tends to be misdiagnosed as a reactive lesion. We present a case report of a Peripheral Odontogenic Fibroma treated by surgical resection and a narrative review of the literature with the purpose of clarifying different aspects of this lesion besides considering it as a possible differential diagnosis of reactive gingival lesions. The purpose of this article is to present a case report of peripheral odontogenic fibroma treated by surgical resection. Also to contribute to the differential diagnosis of gingival reactive lesions.

Whole-genome comparative analysis of the pathogen Piscirickettsia salmonis.

The intracellular pathogen Piscirickettsia salmonis is the etiological agent of piscirickettsiosis, the most important bacterial disease that affects the Chilean salmon industry. Despite its importance, little is known regarding the biology of the pathogen. In this study, recently published sequencing data was used in order to characterize the genome of P. salmonis, defining groups of genes associated with bacterial processes such as, invasion and intracellular survival. Moreover, one Chilean P. salmonis isolate, which is known to be virulent at in vitro and in vivo assays, was sequenced, assembled, annotated and functionally characterized. Whole-genome comparisons between public P. salmonis isolates confirmed the existence of two different genogroups associated with the LF-89 and EM-90 strains, and the bacterial pan and core genome were defined. Additionally, differences were observed at the genomic level between the P. salmonis reference strain and a Norwegian isolate, which is known to produce milder piscirickettsiosis outbreaks. Finally, candidate genes for invasion and intracellular survival were chosen from phylogenetically related bacteria, and annotated in P. salmonis using comparative genomics. These results showed the presence of several genes that might be related to bacterial pathogenesis, for example those of the type III, IV and VI secretion systems, in which some amino acidic differences within both genogroups and the Norwegian isolate were established. Altogether, these results will be relevant for understanding the host-pathogen interaction and further studies, aimed at generating new disease control strategies, should be devised using this information.

Patterns of Piscirickettsia salmonis load in susceptible and resistant families of Salmo salar.

The pathogen Piscirickettsia salmonis produces a systemic aggressive infection that involves several organs and tissues in salmonids. In spite of the great economic losses caused by this pathogen in the Atlantic salmon (Salmo salar) industry, very little is known about the resistance mechanisms of the host to this pathogen. In this paper, for the first time, we aimed to identify the bacterial load in head kidney and muscle of Atlantic salmon exhibiting differential familiar mortality. Furthermore, in order to assess the patterns of gene expression of immune related genes in susceptible and resistant families, a set of candidate genes was evaluated using deep sequencing of the transcriptome. The results showed that the bacterial load was significantly lower in resistant fish, when compared with the susceptible individuals. Based on the candidate genes analysis, we infer that the resistant hosts triggered up-regulation of specific genes (such as for example the LysC), which may explain a decrease in the bacterial load in head kidney, while the susceptible fish presented an exacerbated innate response, which is unable to exert an effective response against the bacteria. Interestingly, we found a higher bacterial load in muscle when compared with head kidney. We argue that this is possible due to the availability of an additional source of iron in muscle. Besides, the results show that the resistant fish could not be a likely reservoir of the bacteria.