Albinism in Natrix tessellata (Serpentes: Natricidae)

Albinism in Natrix tessellata (Serpentes: Natricidae). The Dice Snake, Natrix tessellata, varies in color and pattern, and has several color morphs. Except for melanism, color aberrations are quite rare in the species. Of the two published records of albinism in N. tessellata, the first, from the mid–19th century in Italy is dubious; the second is from Israel. Herein, albinism in juvenile N. tessellata from Slovakia is documented, and the occurrence of albinism in all species of European snakes is discussed.Albinismo em Natrix tessellata (Serpentes: Natricidae). Natrix tessellata varia em cor e padrão e tem várias formas de cores. Exceto pelo melanismo, as aberrações cromáticas são muito raras na espécie. Dos dois registros de albinismo publicados para essa espécie, o primeiro, de meados do século 19 na Itália, é duvidoso; o segundo é de Israel. Documentamos aqui o albinismo em jovens de N. tessellata da Eslováquia e examinamos o contexto de albinismo observado entre outras serpentes da Europa

Comparison of diagnostic methods for Tetracapsuloides bryosalmonae detection in salmonid fish.

Diagnostic accuracy of pathogen detection depends upon the selection of suitable tests. Problems can arise when the selected diagnostic test gives false-positive or false-negative results, which can affect control measures, with consequences for the population health. The aim of this study was to compare sensitivity of different diagnostic methods IHC, PCR and qPCR detecting Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease in salmonid fish and as a consequence differences in disease prevalence. We analysed tissue from 388 salmonid specimens sampled from a recirculating system and rivers in the Czech Republic. Overall prevalence of T. bryosalmonae was extremely high at 92.0%, based on positive results of at least one of the above-mentioned screening methods. IHC resulted in a much lower detection rate (30.2%) than both PCR methods (qPCR32: 65.4%, PCR: 81.9%). While qPCR32 produced a good match with IHC (60.8%), all other methods differed significantly (p < .001) in the proportion of samples determined positive. Both PCR methods showed similar sensitivity, though specificity (i.e., the proportion of non-diseased fish classified correctly) differed significantly (p < .05). Sample preservation method significantly (p < .05) influenced the results of PCR, with a much lower DNA yield extracted from paraffin-embedded samples. Use of different methods that differ in diagnostic sensitivity and specificity resulted in random and systematic diagnosis errors, illustrating the importance of interpreting the results of each method carefully

Nephrocalcinosis in farmed salmonids: diagnostic challenges associated with low performance and sporadic mortality

Disease conditions that involve multiple predisposing or contributing factors, or manifest as low performance and/or low-level mortality, can pose a diagnostic challenge that requires an interdisciplinary approach. Reaching a diagnosis may also be limited by a lack of available clinical profile parameter reference ranges to discriminate healthy fish from those affected by specific disease conditions. Here, we describe our experience investigating poorly performing rainbow trout (Oncorhynchus mykiss) in an intensive recirculation aquaculture, where reaching a final diagnosis of nephrocalcinosis was not as straightforward as one would wish. To list the issues making the diagnosis difficult, it was necessary to consider the creeping onset of the problem. Further diagnostic steps needed to ensure success included obtaining comparative data for fish blood profiles and water quality from both test and control aquacultural systems, excluding infections with salmonid pathogenic agents and evaluating necropsy findings. Major events in the pathophysiology of nephrocalcinosis could be reconstructed as follows: aquatic environment hyperoxia and hypercapnia → blood hypercapnia → blood acid-base perturbation (respiratory acidosis) → metabolic compensation (blood bicarbonate elevation and kidney phosphate excretion) → a rise in blood pH → calcium phosphate precipitation and deposition in tissues. This case highlights the need to consider the interplay between water quality and fish health when diagnosing fish diseases and reaching causal diagnoses

Proliferative kidney disease in rainbow trout (Oncorhynchus mykiss) under intensive breeding conditions: Pathogenesis and haematological and immune parameters.

Proliferative kidney disease (PKD) is an endoparasitic disease of salmonid fish caused by Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea). This study presents a comprehensive view on PKD development in rainbow trout (Oncorhynchus mykiss) reared at an intensive fish breeding facility, with focus on mortality, pathology/histopathology, haematological findings and immune functions. Diseased and reference fish were sampled monthly and time course of natural infection was followed up from the onset of clinical signs (September 2014) to full recovery (January 2015). PKD- associated cumulative mortality was 30% with a peak value in October, while immunohistochemical testing indicated a continuous significant decrease in T. bryosalmonae numbers from September to December; with no parasites detected in January. During peak clinical infection, a significant decrease in red blood cell counts, haematocrit values, haemoglobin concentration, along with a reduction in lymphocytes and a significant phagocyte elevation corresponding with an increase in phagocyte oxidative burst were measured in comparison to control animals. Complement activity and total immunoglobulin plasma concentrations were also elevated, though only during the initial monitoring period (September). Individuals surviving PKD, recovered and were able to fully regenerate both renal structure and haematopoietic parameters to normal levels. Changes in the red blood cell parameters indicate anaemia and a decreased oxygen transportation capacity during the clinical disease phase. Together with an increased oxygen demand at higher temperatures and decreased oxygen solubility this could lead to decompensation and elevated mortality. The stimulation of immune parameters, and especially oxidative phagocytic burst, is likely to have had a strong effect on both, regeneration and elimination of the pathogenic agent

Data_Sheet_1_Nephrocalcinosis in farmed salmonids: diagnostic challenges associated with low performance and sporadic mortality.PDF

Disease conditions that involve multiple predisposing or contributing factors, or manifest as low performance and/or low-level mortality, can pose a diagnostic challenge that requires an interdisciplinary approach. Reaching a diagnosis may also be limited by a lack of available clinical profile parameter reference ranges to discriminate healthy fish from those affected by specific disease conditions. Here, we describe our experience investigating poorly performing rainbow trout (Oncorhynchus mykiss) in an intensive recirculation aquaculture, where reaching a final diagnosis of nephrocalcinosis was not as straightforward as one would wish. To list the issues making the diagnosis difficult, it was necessary to consider the creeping onset of the problem. Further diagnostic steps needed to ensure success included obtaining comparative data for fish blood profiles and water quality from both test and control aquacultural systems, excluding infections with salmonid pathogenic agents and evaluating necropsy findings. Major events in the pathophysiology of nephrocalcinosis could be reconstructed as follows: aquatic environment hyperoxia and hypercapnia → blood hypercapnia → blood acid-base perturbation (respiratory acidosis) → metabolic compensation (blood bicarbonate elevation and kidney phosphate excretion) → a rise in blood pH → calcium phosphate precipitation and deposition in tissues. This case highlights the need to consider the interplay between water quality and fish health when diagnosing fish diseases and reaching causal diagnoses.</p

Comparative mitochondrial phylogeography of water frogs (Ranidae: Pelophylax spp.) from the southwestern Balkans

The genus Pelophylax (water frogs) includes relatively common, widely distributed, and even invasive species, but also endemic taxa with small ranges and limited knowledge concerning their ecology and evolution. Among poorly studied species belong endemics of the southwestern Balkans, namely Pelophylax shqipericus, P. epeiroticus and P. kurtmuelleri. In this study, we focused on the genetic variability of these species aiming to reveal their phylogeographic patterns and Quaternary history. We used 1,088 published and newly obtained sequences of the mitochondrial ND2 gene and a variety of analyses, including molecular phylogenetics and dating, historical demography, and species distribution modeling (SDM). We revelated the existence of two mitochondrial lineages within P. epeiroticus and P. shqipericus that diverged at ~ 0.9 Mya and ~ 0.8 Mya, respectively. Contrarily, no deeply diverged lineages were found in P. kurtmuelleri. Pelophylax kurtmuelleri also shows a close phylogenetic relationship with widely distributed P. ridibundus, suggesting that both represent one evolutionary clade called here P. ridibundus/kurtmuelleri. The estimated split between both lineages in the clade P. ridibundus/kurtmuelleri date back to ~ 0.6 Mya. The divergence between the ridibundus and kurtmuelleri lineages on the ND2 gene is thus lower than the divergence between the two lineages found in P. epeiroticus and P. shqipericus. According to haplotype networks, demographic analyses, and SDM, endemic water frogs survived the last glacial maximum (LGM) in Balkan microrefugia, and their distribution has not changed significantly or even retracted since the LGM. Haplotypes of the kurtmuelleri lineage were also found in northern parts of Europe, where haplotype diversity is however much lower than in the Balkans, suggesting the possible hypothesis of their postglacial expansion to the north

Comparative mitochondrial phylogeography of water frogs (Ranidae: Pelophylax spp.) from the southwestern Balkans

The genus Pelophylax (water frogs) includes relatively common, widely distributed, and even invasive species, but also endemic taxa with small ranges and limited knowledge concerning their ecology and evolution. Among poorly studied species belong endemics of the southwestern Balkans, namely Pelophylax shqipericus, P. epeiroticus and P. kurtmuelleri. In this study, we focused on the genetic variability of these species aiming to reveal their phylogeographic patterns and Quaternary history. We used 1,088 published and newly obtained sequences of the mitochondrial ND2 gene and a variety of analyses, including molecular phylogenetics and dating, historical demography, and species distribution modeling (SDM). We revelated the existence of two mitochondrial lineages within P. epeiroticus and P. shqipericus that diverged at ~ 0.9 Mya and ~ 0.8 Mya, respectively. Contrarily, no deeply diverged lineages were found in P. kurtmuelleri. Pelophylax kurtmuelleri also shows a close phylogenetic relationship with widely distributed P. ridibundus, suggesting that both represent one evolutionary clade called here P. ridibundus/kurtmuelleri. The estimated split between both lineages in the clade P. ridibundus/kurtmuelleri date back to ~ 0.6 Mya. The divergence between the ridibundus and kurtmuelleri lineages on the ND2 gene is thus lower than the divergence between the two lineages found in P. epeiroticus and P. shqipericus. According to haplotype networks, demographic analyses, and SDM, endemic water frogs survived the last glacial maximum (LGM) in Balkan microrefugia, and their distribution has not changed significantly or even retracted since the LGM. Haplotypes of the kurtmuelleri lineage were also found in northern parts of Europe, where haplotype diversity is however much lower than in the Balkans, suggesting the possible hypothesis of their postglacial expansion to the north