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Heart and skeletal muscle inflammation (HSMI) caused by Piscine orthoreovirus (PRV) was first described in farmed Atlantic salmon in Chile in 2011. However, as PRV induces long-lasting infections, it is not known when Chilean farmed salmon may have started to show PRV positivity. This study aimed to evaluate the presence/absence of PRV-1 in formalin-fixed, paraffin-embedded Atlantic salmon heart tissues (FFPE) cultured in Chile during 1992 and 1999. The most frequent histopathological findings in the 42 FFPE blocks were mild focal cardiomyocyte degeneration (57.1%) and a mild focal mononuclear inflammatory infiltrate (21.4%) in the ventricular stratum spongiosum of the heart. One of the 42 heart samples analyzed by RT-qPCR was positive for PRV-1 (2.4%). All samples were negative for other viral and bacterial pathogens that can induce similar histological changes in the heart. Taken together, our results show that PRV-1 has been present in Chile—as a low-virulence genogroup—since at least 1994, 17 years before the first HSMI outbreak in 2011. Finally, archaeovirology can be a valid alternative to contribute to the understanding of the epidemiology of diseases in aquaculture.

Past vegetation and biodiversity dynamics, reconstructed using palaeoecological methods, can contribute to assessing the magnitude of the current biodiversity crisis and anticipating future risks and challenges. Among the different palaeoecological techniques, pollen analysis is probably the most widely used to reconstruct vegetation and plant diversity changes through time. Such reconstructions demand robust and comprehensive calibration studies addressing the pollen representation of extant vegetation to be sound. However, calibration studies are rare in the Mediterranean biodiversity hotspot, particularly regarding plant diversity. Here, we contribute to filling this gap by investigating the modern pollen signature of Mediterranean vegetation across a large environmental gradient in northern Greece. At each sampling site ( n = 61), we quantitatively compared the composition and diversity of plant (vegetation surveys) and pollen assemblages (moss/topsoil samples) using numerical techniques. Further, we compared these terrestrial pollen assemblages with those from lake sediment surface samples of the same region. We found an overall good match between plant and pollen assemblages, with maquis and mixed deciduous forest displaying particularly distinct pollen signatures. In contrast, the high regional importance of pines and oaks and their large pollen production blurred the pollen representation of other forested vegetation types and of shrublands and grasslands. Plant and pollen richness and their evenness showed similar declining trends with increasing altitude, but plant and pollen evenness bore a better match than richness. A more detailed vegetation-specific view on the data suggests that pine pollen seriously affected pollen richness and evenness in most of the pine-dominated stands. Lastly, our results suggest a rather straightforward application of vegetation-pollen relationships from moss/topsoil samples to interpret pollen assemblages from lakes in Mediterranean settings.

Bacterial kidney disease (BKD) is widespread in many areas of the world and can cause substantial economic losses for the salmon aquaculture industry. The objective of this study was to investigate the pathophysiological response and gene expression profiles related to the immune response at different water temperatures and to identify the best immunopathological biomarkers to define a phenotype of resistance to BKD. The abundance of msa transcripts of R. salmoninarum in the head kidney was significantly higher in infected fish at 11°C. R. salmoninarum induced significantly more severe kidney lesions, anemia and impaired renal function at 11°C. In addition, the expression pattern of the genes related to humoral and cell-mediated immune responses in infected fish at 11°C and 15°C was very similar, although R. salmoninarum induced a significantly greater downregulation of the adaptive immune response genes at the lower water temperature. These results could be due to a suppressed host response directly related to the lowest water temperature and/or associated with a delayed host response related to the lowest water temperature. Although no significant differences in survival rate were observed, fish infected at the lowest temperature showed a higher probability of death and delayed the mortality curve during the late stage of infection (35 days after infection). Thirty-three immunopathological biomarkers were identified for potential use in the search for a resistance phenotype for BKD, and eight were genes related specifically to the adaptive cell-mediated immune response.

Bacterial kidney disease (BKD) is widespread in many areas of the world and can cause substantial economic losses for the salmon aquaculture industry. The objective of this study was to investigate the pathophysiological response and gene expression profiles related to the immune response at different water temperatures and to identify the best immunopathological biomarkers to define a phenotype of resistance to BKD. The abundance of msa transcripts of R. salmoninarum in the head kidney was significantly higher in infected fish at 11°C. R. salmoninarum induced significantly more severe kidney lesions, anemia and impaired renal function at 11°C. In addition, the expression pattern of the genes related to humoral and cell-mediated immune responses in infected fish at 11 and 15°C was very similar, although R. salmoninarum induced a significantly greater downregulation of the adaptive immune response genes at the lower water temperature. These results could be due to a suppressed host response directly related to the lowest water temperature and/or associated with a delayed host response related to the lowest water temperature. Although no significant differences in survival rate were observed, fish infected at the lowest temperature showed a higher probability of death and delayed the mortality curve during the late stage of infection (35 days after infection). Thirty-three immunopathological biomarkers were identified for potential use in the search for a resistance phenotype for BKD, and eight were genes related specifically to the adaptive cell-mediated immune response.