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Kamijima, Japan

Red sea bream is one of the most important aquaculture fish species in Japan. To improve the productivity of this fish during seed production, improved growth traits and reduced size variation are needed. In this study, we assessed parental contribution of fast- and slow-growing individuals observed in two different rearing phases in a mass production lot: (1) 50 dph reared in a tank and (2) 200 dph reared in a net cage. We also assessed GH gene (pmaGH) polymorphisms based on a previously developed minisatellite DNA marker. Specific broodstock individuals were significantly associated with fast- or slow-growing individuals at 50 dph and 200 dph. Significant differences in pmaGH minisatellite allele frequencies were observed between fast- and slow-growing groups at 50 dph in the frequency of two alleles (pmaGH-740 and pmaGH-900, respectively). Combining the results of DNA parentage analysis and pmaGH minisatellite allele analysis, one dam and two sires, possessing pmaGH-740, were significantly associated with the slow-growing groups. These results suggest that the minisatellite marker of pmaGH could be a useful tool for growth selection of this fish species. © 2015 The Authors. Published by Elsevier B.V.

Sawayama E.,Marua Suisan Co. | Takagi M.,Ehime University
Nippon Suisan Gakkaishi (Japanese Edition) | Year: 2011

Transparent individuals have been identified in juveniles of a hatchery population of red sea bream. This study characterized the numbers of melanophores, xantphores, and erythrophores, in normal and transparent individuals. The transparent individuals were partly transparent at the 40 day-post-hatch stage and the numbers of all chromatophores were significantly lower. In 100 day-post-hatch juveniles, the transparent individuals exhibited slight differences to normal individuals. However, the numbers of xantphores and erythrophores remained significantly lower. The parentage of normal and transparent individuals was identified by five microsatellite loci. Analysis indicated that normal individuals were generated from 6 female and 8 male parents, and 15 parental pairs were identified. However, all transparent individuals were generated from 1 female with 5 male parents. Our results suggest that the transparent individuals identified in larvae of the hatchery population of red sea bream had arisen via genetic effects.

Sawayama E.,Marua Suisan Co. | Takagi M.,Ehime University
Nippon Suisan Gakkaishi (Japanese Edition) | Year: 2012

Artificially raised Japanese flounder exhibiting short body length were morphologically characterized and genetic investigations were conducted using microsatellite DNA. Individuals exhibiting short and normal body lengths were collected 60 days after hatching. Flounder with short bodies were morphologically analyzed by soft X-ray and divided into three groups, A, B and C, based upon body shapes and the positions of fused vertebrae. All short bodied individuals exhibited highly fused vertebrae. Main vertebrae fusion points were determined as follows: type A: all positions upon the vertebrae, type B: vertebra numbers 1 to 4 and 17 to 30, and type C: vertebra numbers 1 to 4 and 19 to 36. The frequency of these short body individuals observed in this study was 1.7%. Four microsatellite markers [Pol-1*, -3 *, -4*, -5*) were deployed for parentage analysis and 99.3% of specimens were successfully assigned. One each of dam and sire were significantly associated with type B short body individuals. Furthermore, we identified that the same sire was also significantly associated with type C short body individuals. These results suggest that genetic factors are probably one of the underlying factors of short body individuals identified in juvenile Japanese flounder.

Sawayama E.,Marua Suisan Co. | Asahina K.,Nihon University | Takagi M.,Ehime University
Aquaculture | Year: 2014

Skeletal malformations are a serious problem in seed production of Japanese flounder Paralichthys olivaceus, and genetic effect is sometimes suggested as one of the causative factors. In this study, we examined a skeletal deformity named incomplete ossification, and studied its morphological character and parentage assessment of the deformity by microsatellite DNA markers in the hatchery produced offspring at a commercial farm. Naturally spawned fertilized eggs from flounder broodstocks (eight dams and 19 sires) were introduced into 50. kl tanks and reared with normal procedures. We conducted two lots of seed production with lot 2 started one-week later under the same rearing conditions as lot 1. Deformed and normal individuals were collected at 35. days post-hatch and used for further analysis. Body shape of deformed individuals was narrower than that of normal individuals. Moreover, alcian blue-alizarin red staining revealed that vertebrae and the cranium were partly ossified and the appendicular skeleton and fin rays were not ossified even if those parts were completely ossified in normal individuals. DNA parentage analysis revealed that one dam and sire in lot 1 and a dam and two sires in lot 2 were significantly related to the deformed individuals. The dam and sire significantly related to the deformed individuals were the same in the two lots, even though parentages related to normal individuals were different in the two lots. Our results suggest that this type of deformity of Japanese flounder is caused by incomplete ossification and probably affected by genetic factors. Therefore, pedigree selection will be useful for prevention of this deformity. © 2013 Elsevier B.V.

Sawayama E.,Marua Suisan Co. | Sakamoto S.,Oriental Yeast Co. | Takagi M.,Ehime University
Fisheries Science | Year: 2012

To elucidate possible causes of skeletal malformations in larval Japanese flounder, we reared larvae fed rotifers enriched with three types of preserved Nannochloropsis (fresh, refrigerated, and frozen). The incidence of malformations at 50 days post hatch ranged from 14. 5 to 38. 5 % within the three experimental groups, and elongation of the lower jaw (LJ) was the most frequently observed malformation, ranging from 68 to 89 % of total malformations. We also investigated larval parentages using microsatellite markers. Parentage analysis of the fresh Nannochloropsis group showed that one sire and a pair generated significant numbers of LJ-elongated individuals. In the refrigerated Nannochloropsis group, one dam and two sires generated significant numbers of LJ-elongated individuals. In the frozen Nannochloropsis group, no broodstocks or pairs generated significant numbers of LJ-elongated individuals. Our results suggest that LJ elongation in Japanese flounder likely results from the application of different types of preserved Nannochloropsis during rotifer feeding stage. However, there is also some level of genetic influence associated with this deformity. © 2012 The Japanese Society of Fisheries Science.

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