Salmonid fish: model organisms to study cardiovascular morphogenesis in conjoined twins?

Fjelldal, Per Gunnar; Solberg, Monica Favnebøe; Hansen, Tom; Vågseth, Tone; Glover, Kevin A.; Kryvi, Harald

doi:10.1186/s12861-016-0125-x

Cited by 11 publications

(10 citation statements)

References 37 publications

(46 reference statements)

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“…Al-Harbi (2001) and Hikita (1955) both present cases of common carp Cyprinus carpio and chum salmon Oncorhynchus keta, respectively, with pugheads and shortened opercula. Another interesting case describe two ventrally conjoined twins of Atlantic salmon Salmo salar, where one of the individuals was pugheaded and, in addition, showed a downward curved lower jaw, missing left pelvic fin, abnormally small pectoral fins, and a severely deformed vertebral column with many fused vertebrae (Fjelldal et al 2016). A similar case of salmonid conjoined twin embryos, where one twin was pugheaded, was described by de Quatrefages (1888; see Gudger 1929).…”

Section: Description Of the Deformitymentioning

confidence: 82%

Pugheadedness in Fishes

Näslund

Jawad

2021

Reviews in Fisheries Science & Aquaculture

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This review summarizes the current state of knowledge of pugheadedness in fish. Records in the scientific literature range from detailed descriptions to brief notes and mere remarks. In total, at least 164 species from 60 families were identified to exhibit pugheadedness, with records published over a span of 465 years (1555 − 2020). The main osteological feature behind pugheadedness appears to be shortening or deformation of the parasphenoid bone, which leads to additional deformations of the ethmovomer-and frontal region. Several other deformations and abnormalities of other cranial bones, eyes, and tongue are occasionally observed, depending on the severity of the pugheadedness. Possible cases in elasmobranchs are also encountered, although the developmental causation may differ from actinopterygians, since their crania have a different organization. Natural cases of pugheadedness are found world-wide, covering a wide range of environments and lifestyles (freshwater-, brackish-and marine environments; benthic, neritic and pelagic species). Cases are found in all life-stages, from embryo to mature adults, suggesting that it does not necessarily lead to early-life mortality. There is some evidence for natural selection acting against pugheaded individuals, likely because of e.g. inappropriately functioning mouth parts, sense organs, and possibly brain deformation. High numbers of pugheads are mainly found in aquaculture, but moderate numbers have been found at some localities also in the wild. Abnormally high occurrence in the wild is commonly attributed to pollution, non-normal water chemistry parameters, or temperature. The causation, however, it typically speculated upon. Based on the reviewed literature, there is support for several causative factors, including genetic mutation and embryonic environmental conditions (toxic and non-toxic) affecting development. Pugheadedness, as the term has been used in the literature, is not a single well-defined pathology, but rather a suite of pathological conditions with similar phenotypic expression.

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Section: Description Of the Deformitymentioning

confidence: 82%

Pugheadedness in Fishes

Näslund

Jawad

2021

Reviews in Fisheries Science & Aquaculture

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“…In order to assign parents to the juveniles reared in the mixed-family tanks, and to examine inheritance patterns in the eggs and juveniles sampled, all samples were genotyped with a panel of 18 microsatellite markers on an ABI sequencer at the genetics laboratory of the Institute of Marine Research in Bergen, Norway. This panel of microsatellites has been genotyped in this laboratory for more than a decade, involving the analysis of > 50,000 salmon to study population genetics [66,71,72], reconstruct pedigree [59,73,74], permit identification of conjoined twins [75], conduct forensic investigations to identify the source of escaped salmon back to their farms of origin which also included blind controls and documentation of genotyping error rates [76,77], and finally, for identification of triploids, trisomic and haploid individuals [5,7,55,69,78]. Personnel in the laboratory are therefore highly experienced in interpreting genotypes of these markers for a variety of purposes including polyploidy.…”

Section: Genotypingmentioning

confidence: 99%

Chromosome aberrations in pressure-induced triploid Atlantic salmon

et al. 2020

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Background: Triploid organisms have three sets of chromosomes. In Atlantic salmon, hydrostatic pressure treatment of newly fertilized eggs has been extensively used to produce triploids which are functionally sterile due to their unpaired chromosomes. These fish often perform poorly on commercial farms, sometimes without explanation. Inheritance patterns in individuals subjected to pressure treatment have not been investigated in Atlantic salmon thus far. However, work on other species suggests that this treatment can result in aberrant inheritance. We therefore studied this in Atlantic salmon by genotyping 16 polymorphic microsatellites in eyed eggs and juveniles which had been subjected to pressure-induction of triploidy. Communally reared juveniles including fish subjected to pressure-induction of triploidy and their diploid siblings were included as a control. Results: No diploid offspring were detected in any of the eggs or juveniles which were subjected to hydrostatic pressure; therefore, the induction of triploidy was highly successful. Aberrant inheritance was nevertheless observed in 0.9% of the eggs and 0.9% of the juveniles that had been subjected to pressure treatment. In the communally reared fish, 0.3% of the fish subjected to pressure treatment displayed aberrant inheritance, while their diploid controls displayed 0% aberrant inheritance. Inheritance errors included two eyed eggs lacking maternal DNA across all microsatellites, and, examples in both eggs and juveniles of either the maternal or paternal allele lacking in one of the microsatellites. All individuals displaying chromosome aberrations were otherwise triploid. Conclusions: This is the first study to document aberrant inheritance in Atlantic salmon that have been subjected to pressure-induction of triploidy. Our experiments unequivocally demonstrate that even when induction of triploidy is highly successful, this treatment can cause chromosome aberrations in this species. Based upon our novel data, and earlier studies in other organisms, we hypothesize that in batches of Atlantic salmon where low to modest triploid induction rates have been reported, aberrant inheritance is likely to be higher than the rates observed here. Therefore, we tentatively suggest that this could contribute to the unexplained poor performance of triploid salmon that is occasionally reported in commercial aquaculture. These hypotheses require further investigation.

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“…For salmonids, most reports about malformations in early life stages describe external morphological variations. Twinning, pug headedness, lower jaw malformations and axial deviations (lordosis, kyphosis and scoliosis) have been described (Eriksen, Bakken, Espmark, Braastad, & Salte, ; Fjelldal et al., ; Johnson et al., ; Leduc, ; Mahrosh et al., ; Quatrefages, ; Yamamoto, Kobayashi, & Kuramoto, ). Few reports link external phenotypes with deformities of internal structures.…”

Section: Introductionmentioning

confidence: 99%

“…axial deviations (lordosis, kyphosis and scoliosis) have been described (Eriksen, Bakken, Espmark, Braastad, & Salte, 2006;Fjelldal et al, 2016;Johnson et al, 1998;Leduc, 1978;Mahrosh et al, 2014;Quatrefages, 1888;Yamamoto, Kobayashi, & Kuramoto, 1996). Few reports link external phenotypes with deformities of internal structures.…”

mentioning

confidence: 99%

The external phenotype–skeleton link in post‐hatch farmed Chinook salmon (Oncorhynchus tshawytscha)

Clercq

Perrott

Davie

et al. 2017

Journal of Fish Diseases

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Skeletal deformities in farmed fish are a recurrent problem. External malformations are easily recognized, but there is little information on how external malformations relate to malformations of the axial skeleton: the external phenotype-skeleton link. Here, this link is studied in post-hatch to first-feed life stages of Chinook salmon (Oncorhynchus tshawytscha) raised at 4, 8 and 12°C. Specimens were whole-mount-stained for cartilage and bone, and analysed by histology. In all temperature groups, externally normal specimens can have internal malformations, predominantly fused vertebral centra. Conversely, externally malformed fish usually display internal malformations. Externally curled animals typically have malformed haemal and neural arches. External malformations affecting a single region (tail malformation and bent neck) relate to malformed notochords and early fusion of fused vertebral centra. The frequencies of internal malformations in both externally normal and malformed specimens show a U-shaped response, with lowest frequency in 8°C specimens. The fused vertebral centra that occur in externally normal specimens represent a malformation that can be contained and could be carried through into harvest size animals. This study highlights the relationship between external phenotype and axial skeleton and may help to set the framework for the early identification of skeletal malformations on fish farms.

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Salmonid fish: model organisms to study cardiovascular morphogenesis in conjoined twins?

Cited by 11 publications

References 37 publications

Pugheadedness in Fishes

Pugheadedness in Fishes

Chromosome aberrations in pressure-induced triploid Atlantic salmon

The external phenotype–skeleton link in post‐hatch farmed Chinook salmon (Oncorhynchus tshawytscha)

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