Proliferative kidney disease caused by the myxozoan parasite Tetracapsuloides bryosalmonae has be... more Proliferative kidney disease caused by the myxozoan parasite Tetracapsuloides bryosalmonae has been actively studied in juvenile salmonids for decades. However, very little is known about parasite prevalence and its geographical and intra‐host distribution at older life stages. We screened T. bryosalmonae among adult sea trout (Salmo trutta) (n = 295) collected along the Estonian Baltic Sea coastline together with juvenile trout from 33 coastal rivers (n = 1752) to assess spatial infection patterns of the adult and juvenile fish. The parasite was detected among 38.6% of adult sea trout with the prevalence increasing from west to east, and south to north, along the coastline. A similar pattern was observed in juvenile trout. Infected sea trout were also older than uninfected fish and the parasite was detected in sea trout up to the age of 6 years. Analysis of intra‐host distribution of the parasite and strontium to calcium ratios from the otoliths revealed that (re)infection through freshwater migration may occur among adult sea trout. The results of this study indicate that T. bryosalmonae can persist in a brackish water environment for several years and that returning sea trout spawners most likely contribute to the parasite life cycle by transmitting infective spores.
Abstract 48 novel tetranucleotide microsatellite loci were developed for the noble crayfish ( Ast... more Abstract 48 novel tetranucleotide microsatellite loci were developed for the noble crayfish ( Astacus astacus ) using Illumina MiSeq next generation sequencing technology. It was demonstrated that 25 loci were polymorphic and 19 loci could be co-amplified in a single multiplex polymerase chain reaction (PCR) assay and genotyped as a single panel on Applied Biosystems 3500 Genetic Analyser. The 19-plex assay was tested on 232 individuals of A. astacus originating from seven wild populations in Czech Republic and in Estonia. The multiplex assay designed in this study can be successfully applied in studies requiring high genetic resolution, such as population structuring, relatedness analysis, and stock identification. 21 loci were also successfully cross-amplified in the narrow-clawed crayfish ( Astacus leptodactylus ) from which 14 were polymorphic. In addition, 13 loci (both monomorphic and polymorphic) possessed species-specific allele size range in A. astacus and A. leptodactylus and can be applied for detecting possible hybrids between these sister species. Statement of relevance The novel 19-plex microsatellite assay can be applied for genetic management of captive stocks of the noble crayfish (selection of strains, planning of matings, avoiding of inbreeding) and in studies requiring high genetic resolution, such as parentage assessment, relatedness analysis or strain identification.
Many salmonid fish populations are threatened by genetic homogenization, primarily due to introgr... more Many salmonid fish populations are threatened by genetic homogenization, primarily due to introgressive hybridization with hatchery‐reared conspecifics. By applying genomewide analysis using two molecular marker types (1986 SNPs and 17 microsatellites), we assessed the genetic impacts of inadvertent gene flow via straying from hatchery releases on wild populations of Atlantic salmon in the Gulf of Finland, Baltic Sea, over 16 years (1996–2012). Both microsatellites and SNPs revealed congruent population genetic structuring, indicating that introgression changed the genetic make‐up of wild populations by increasing genetic diversity and reducing genetic divergence. However, the degree of genetic introgression varied among studied populations, being higher in the eastern part and lower in the western part of Estonia, which most likely reflects the history of past stocking activities. Using kernel smoothing and permutation testing, we detected considerable heterogeneity in introgression patterns across the genome, with a large number of regions exhibiting nonrandom introgression widely dispersed across the genome. We also observed substantial variation in nonrandom introgression patterns within populations, as the majority of genomic regions showing elevated or reduced introgression were not consistently detected among temporal samples. This suggests that recombination, selection and stochastic processes may contribute to complex nonrandom introgression patterns. Our results suggest that (i) some genomic regions in Atlantic salmon are more vulnerable to introgressive hybridization, while others show greater resistance to unidirectional gene flow; and (ii) the hybridization of previously separated populations leads to complex and dynamic nonrandom introgression patterns that most likely have functional consequences for indigenous populations.
qPCR quantification cycle as inferred by the online tool 'Real-time PCR Miner' http://min... more qPCR quantification cycle as inferred by the online tool 'Real-time PCR Miner' http://miner.ewindup.info/ given per plate and well, including amplification efficiencies and efficiency-corrected quantification cycl
Proliferative kidney disease caused by the myxozoan parasite Tetracapsuloides bryosalmonae has be... more Proliferative kidney disease caused by the myxozoan parasite Tetracapsuloides bryosalmonae has been actively studied in juvenile salmonids for decades. However, very little is known about parasite prevalence and its geographical and intra‐host distribution at older life stages. We screened T. bryosalmonae among adult sea trout (Salmo trutta) (n = 295) collected along the Estonian Baltic Sea coastline together with juvenile trout from 33 coastal rivers (n = 1752) to assess spatial infection patterns of the adult and juvenile fish. The parasite was detected among 38.6% of adult sea trout with the prevalence increasing from west to east, and south to north, along the coastline. A similar pattern was observed in juvenile trout. Infected sea trout were also older than uninfected fish and the parasite was detected in sea trout up to the age of 6 years. Analysis of intra‐host distribution of the parasite and strontium to calcium ratios from the otoliths revealed that (re)infection through freshwater migration may occur among adult sea trout. The results of this study indicate that T. bryosalmonae can persist in a brackish water environment for several years and that returning sea trout spawners most likely contribute to the parasite life cycle by transmitting infective spores.
Abstract 48 novel tetranucleotide microsatellite loci were developed for the noble crayfish ( Ast... more Abstract 48 novel tetranucleotide microsatellite loci were developed for the noble crayfish ( Astacus astacus ) using Illumina MiSeq next generation sequencing technology. It was demonstrated that 25 loci were polymorphic and 19 loci could be co-amplified in a single multiplex polymerase chain reaction (PCR) assay and genotyped as a single panel on Applied Biosystems 3500 Genetic Analyser. The 19-plex assay was tested on 232 individuals of A. astacus originating from seven wild populations in Czech Republic and in Estonia. The multiplex assay designed in this study can be successfully applied in studies requiring high genetic resolution, such as population structuring, relatedness analysis, and stock identification. 21 loci were also successfully cross-amplified in the narrow-clawed crayfish ( Astacus leptodactylus ) from which 14 were polymorphic. In addition, 13 loci (both monomorphic and polymorphic) possessed species-specific allele size range in A. astacus and A. leptodactylus and can be applied for detecting possible hybrids between these sister species. Statement of relevance The novel 19-plex microsatellite assay can be applied for genetic management of captive stocks of the noble crayfish (selection of strains, planning of matings, avoiding of inbreeding) and in studies requiring high genetic resolution, such as parentage assessment, relatedness analysis or strain identification.
Many salmonid fish populations are threatened by genetic homogenization, primarily due to introgr... more Many salmonid fish populations are threatened by genetic homogenization, primarily due to introgressive hybridization with hatchery‐reared conspecifics. By applying genomewide analysis using two molecular marker types (1986 SNPs and 17 microsatellites), we assessed the genetic impacts of inadvertent gene flow via straying from hatchery releases on wild populations of Atlantic salmon in the Gulf of Finland, Baltic Sea, over 16 years (1996–2012). Both microsatellites and SNPs revealed congruent population genetic structuring, indicating that introgression changed the genetic make‐up of wild populations by increasing genetic diversity and reducing genetic divergence. However, the degree of genetic introgression varied among studied populations, being higher in the eastern part and lower in the western part of Estonia, which most likely reflects the history of past stocking activities. Using kernel smoothing and permutation testing, we detected considerable heterogeneity in introgression patterns across the genome, with a large number of regions exhibiting nonrandom introgression widely dispersed across the genome. We also observed substantial variation in nonrandom introgression patterns within populations, as the majority of genomic regions showing elevated or reduced introgression were not consistently detected among temporal samples. This suggests that recombination, selection and stochastic processes may contribute to complex nonrandom introgression patterns. Our results suggest that (i) some genomic regions in Atlantic salmon are more vulnerable to introgressive hybridization, while others show greater resistance to unidirectional gene flow; and (ii) the hybridization of previously separated populations leads to complex and dynamic nonrandom introgression patterns that most likely have functional consequences for indigenous populations.
qPCR quantification cycle as inferred by the online tool 'Real-time PCR Miner' http://min... more qPCR quantification cycle as inferred by the online tool 'Real-time PCR Miner' http://miner.ewindup.info/ given per plate and well, including amplification efficiencies and efficiency-corrected quantification cycl
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