PLoS One. Published online Apr Received Jan 18; Accepted Mar This article has been cited by other articles in PMC. The F1 hybrids of these two scallops exhibited a large increase in production traits and some other interesting new characteristics. To understand the genetic basis of this heterosis, nuclear gene and partial mtDNA sequences, and genomic in situ hybridization GISH were employed to analyze the genomic organization of the hybrids.
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PLoS One. Published online Apr Received Jan 18; Accepted Mar This article has been cited by other articles in PMC. The F1 hybrids of these two scallops exhibited a large increase in production traits and some other interesting new characteristics.
To understand the genetic basis of this heterosis, nuclear gene and partial mtDNA sequences, and genomic in situ hybridization GISH were employed to analyze the genomic organization of the hybrids. Amplification of the ribosomal DNA internal transcribed spacer ITS showed that the parental ITS sequences were present in all the hybrid individuals, illustrating that the hybrid offspring inherited nuclear DNA from both parents.
Sequence analyses of the ITS region further confirmed that the hybrids harbored alleles from their parents; some recombinant variants were also detected, which revealed some alterations in the nuclear genetic material of the hybrids. The analysis of mitochondrial 16S rDNA showed that the hybrids possessed sequences that were identical to the 16S rDNA of the female parents, proving a matrilineal inheritance of mitochondrial genes in scallops. In addition, GISH clearly discriminated between the parental chromosomes and indicated a combination of haploid genomes of duplex parents in the hybrids.
The genetic analyses in our study illustrated that the F1 hybrids inherited nuclear material from both parents and cytoplasmic genetic material maternally, and some variations occurred in the genome, which might contribute to a further understanding of crossbreeding and heterosis in scallop species.
Introduction Distant hybridization is not only a useful way of producing heterosis but also an effective method of expanding the source of species variation and breeding new varieties. Such variation has provided the conditions for genetic improvement in the aquaculture industry. Scallops are one of the most ecologically and economically important bivalve groups in the world. Crossbreeding among species has been attempted to improve the productivity and disease resistance of some commercial scallop species, and these efforts have proven the feasibility of this approach  — .
The analysis of the chromosomal components in hybrids between Mimachlamys nobilis and C. The above analyses of the genomic constitution of interspecific hybrids and the previous studies about heterosis in scallops have mostly focused on hybrid embryos at an early developmental stage, mainly because viable adult hybrid scallops have been rarely reported.
Although Yang et al. The bay scallop Argopecten irradians irradians Lamarck, is naturally distributed along the Atlantic coast from New Jersey northward to Cape Cod . This species was introduced to China from the US in  , and a vast aquaculture industry based on the scallop soon developed in northern China.
The Peruvian scallop A. These two scallops are both hermaphroditic Argopecten scallops and have the same chromosome number, with similar karyotypes  , . However, the animals have distinct sizes, life spans and temperature tolerance . In and , the Peruvian scallop was introduced to China and was successfully hybridized with the bay scallop.
The hybrid offspring exhibited extraordinary heterosis in growth in addition to some new features . However, the genomic constitution of the hybrids and the contribution rate of the parents to the hybrids have remained unclear.
To understand the genetic basis of the observed heterosis, we analyzed the genome organization of the A. The inheritance of nuclear and mitochondrial genetic material from the parents to the F1 progeny was first investigated through an analysis of the nuclear gene and mtDNA sequences, involving the internal transcribed spacer ITS region and 16S rDNA, respectively. Genomic in situ hybridization GISH was then employed to identify the chromosomal composition of the hybrid larvae at the cytogenetic level.
Results The ITS region was successfully amplified in all of the 40 individuals tested, and the results of polyacrylamide gel electrophoresis are shown in Fig. A band of approximately bp was amplified using Peruvian scallop DNA, and a set of larger bands bp were amplified for the bay scallops. The presence of multiple bands for some parents and hybrid individuals, such as in Fig.
S1 , lines 3, 4, 7, 10 and 11, could be attributed to the ITS diversity among different repeat units. The total length of the ITS region was — bp, with The alignment of the ITS sequences showed identical pairs, 3 transitional pairs and 4 transversional pairs in PP and identical pairs, 2 transitional pairs and no transversional pairs in BB. An alignment analysis of all the ITS sequences of the parents and hybrid offspring showed that the polymorphism was caused by indels and nucleotide substitutions, with all indel polymorphic sites being located in the central regions of ITS1 and ITS2.
In 96 randomly selected clones from the hybrid individuals, 88 were identified as representative of parental ITS alleles, involving half of the PP alleles and half of the BB alleles.
The number of these two types of alleles in each hybrid individual was also nearly equal. In addition, eight recombinant variants in four individuals were identified and comprised segmental sequences of PP and BB. A simplified alignment of the parental ITS representatives and eight recombinant variants are shown in Fig.
Coquille St-Jacques : Vraie Coquille ou Pétoncle ?
Search Menu Abstract Although some external coloration and pigmentation patterns in molluscan shells may be attributable to environmental factors, most variation in these phenotypic characters depends on uncomplicated genetic mechanisms. Genetic research on inheritance of color variations in the north-Chilean scallop Argopecten purpuratus has now been expanded to analyze color segregation in juvenile scallops produced under controlled conditions employing self- and cross-fertilization. Calculations from the results were used for comparison with different numerical models based on Mendelian inheritance, and results were also obtained on the inheritance of a dorsoventral white line often observed on the left upper valve in this species. The results confirmed the hereditary basis for color variation in the shell of this scallop, suggesting a simple, dominant model of epistasis to explain the distribution of the different color variants observed purple, brown, orange, yellow, and white.
Argopecten purpuratus avec corail
The 16 n chromosomes originating from A. The green chromosomes are from A. One chromosome from A. In these experiments, the hybrid larvae were found to be viable, whereas viable adult hybrids were not found. Yang et al.
Draft genome of the Peruvian scallop Argopecten purpuratus.
External links Habitat This scallop is natural to certain bays in the Southern west coast of south America, from Peru to Chile. In most growth areas, the harvesting of natural grown scallops has been replaced by aquaculture operations. The aquaculture operations consist in re-stocking the natural areas, taking care of the scallops along the grow out period and harvesting at the end of the cycle. Thanks to this practices, the natural banks have recovered and are able to maintain a sustainable production level. In some species, the valves are highly calcified, and many are somewhat irregular in shape.