Construction of Three High-Density Genetic Linkage Maps and Dynamic QTL Mapping of Growth Traits in Yellow River Carp (Cyprinus carpio haematopterus)

To provide the theoretical basis for researching growth, development, and molecular marker-assisted breeding of the economically important Yellow River carp (Cyprinus carpio haematopterus) using dynamic quantitative trait locus (QTL) mapping, we constructed three genetic linkage maps from 207 progeny using a new modified genotyping-by-sequencing method. The three maps contained 16,886, 16,548, and 7482 single nucleotide polymorphism markers, respectively, with an average interval of 0.36 cM, 0.45 cM, and 1.00 cM. We identified 148 QTLs related to four growth traits that were located on 25 chromosomes from three growth stages of Yellow River carp. A total of 32, 36, 43, and 37 QTLs were associated with body length, height, width, and weight, respectively. Among them, 47 QTLs were detected for only one growth trait in one stage, but all of the other QTLs were co-localized. Of the 14 main QTLs, 13 were located on chromosome 12, which suggests the presence of growth-related genes on this chromosome. We then detected 17 candidate genes within 50 K upstream and downstream of the 14 main QTLs. This is the first report of the dynamic QTL mapping of growth traits of Yellow River carp, and the results can be used in future studies of growth, development, and molecular-assisted breeding of this species.

ALIEN SPECIES OF FISH HELMINTHS OF BELARUS

The article provides data on the species composition of alien helminth species, which infest introduced fish species in pond fish farms, and also the literature data on natural reservoirs of Belarus. Seven alien helminth species have been revealed in introduced fish in reservoirs of Belarus ( Khawia sinensis Hsü, 1935, Schyzocotyle acheilognathi (Yamaguti, 1934) , Caryophyllaeus fimbriceps Annenkova-Chlopina, 1919, Philometroides cyprini (Ishii, 1931), Dactylogyrus dulkeiti Bychowsky, 1936, Bothriocephalus claviceps (Goeze, 1782) , Anguillicola crassus Kuwahara 1974). All species of helminths excluding the nematode A.crassus and the cestode B.claviceps - parasites of the eels Anguilla anguilla , were introduced to Belarus with the seeding of Cyprinus carpio haematopterus (Linnaeus, 1758) from the Far East. The invasive species of helminths ( K. sinensis, S. acheilognathi, P. cyprini, A. crassus ), which affect fishery by causing the death of farmed fish, are singled out.

The Discovery of Asian Fish Tapeworm (Schyzocotyle Acheilognathi) and Schyzocotyle Sp. In Western Australia May Pose a Threat to the Health of Endemic Native Fishes

PurposeThe Asian fish tapeworm (Schyzocotyle acheilognathi) is an important fish parasite with a wide host range that infects over 300 species of fish worldwide. Schyzocotyle acheilognathi has been reported from eastern coastal areas of Australia, but has not been previously reported in Western Australia (WA). MethodsDuring a control program for invasive freshwater fishes in south-western WA, a region with a unique and highly endangered freshwater fish fauna, tapeworms identified as S. acheilognathi from their distinctive scolex morphology were found at a prevalence of 3.3% in goldfish (Carassius auratus), 37.0% in koi carp (Cyprinus carpio haematopterus), and 65.0% in eastern mosquitofish (Gambusia holbrooki). For molecular confirmation, the 18S rRNA gene was targeted at hypervariable region V4 using conventional PCR and Sanger sequencing.ResultsKoi carp isolates were 100.0% identical to S. acheilognathi isolated from varying hosts including the red shiner (Cyprinella lutrensis) and a human sample. Sequences from two eastern mosquitofish were identified as S. acheilognathi, but formed a discrete subclass and may represent a novel genotype. Isolates from two other eastern mosquitofish and two goldfish formed a distinct clade with only 91.9% similarity to previously sequenced isolates of S. acheilognathi, indicating a potentially novel Schyzocotyle species. ConclusionThis emphasises the importance of molecular identification methods in addition to morphological identification. The presence and potential for spread of these parasites in south-western WA may threaten the health of native fishes, which are immunologically naïve to this introduced parasite. Immediate control or containment measures should be implemented to halt the spread of these parasites.

The Asian fish tapeworm (Schyzocotyle acheilognathi) discovered in Western Australia may pose a threat to the health of endemic native fishes

The Asian fish tapeworm (Schyzocotyle acheilognathi) is an important fish parasite with a wide host range that infects over 300 species of fish worldwide. Schyzocotyle acheilognathi has been reported from eastern coastal areas of Australia, but has not been previously reported in Western Australia (WA). During a control program for invasive freshwater fishes in south-western WA, a region with a unique and highly endangered freshwater fish fauna, tapeworms identified as S. acheilognathi from their distinctive scolex morphology were found at a prevalence of 3.3% in goldfish (Carassius auratus), 37.0% in koi carp (Cyprinus carpio haematopterus) and 65.0% in eastern gambusia (Gambusia holbrooki) in a small suburban lake to the north of Perth. For molecular confirmation, the 18S ribosomal RNA gene was targeted at hypervariable V4 region. Koi carp isolates were 100% identical to S. acheilognathi isolated from varying hosts, including the red shiner (Cyprinella lutrensis) and a human sample. Sequences obtained from two eastern gambusia were identified as S. acheilognathi, but formed a discrete cluster and may represent a novel genotype. Isolates from two other eastern gambusia and two goldfish formed a distinct clade with only 91.9% similarity to previously sequenced isolates of S. acheilognathi. This emphasizes the importance of molecular identification methods in addition to morphological identification. The presence and potential for transmission of these parasites in south-western WA may threaten the health of native fishes, which are immunologically naïve to this introduced parasite. Immediate control or containment measures should be implemented to halt the spread of these parasites.