Browsing by Author "Arai, Katsutoshi"
ArticleK Adachi, K Arai, MR de la Peña, S Moriyama & SI Okumura -
Journal of Shellfish Research, 2018 - National Shellfisheries AssociationGenome size (C-value) and the percentage of adenine and thymine nucleotides in the genome (AT content) are fundamental characteristics of every species, and very important parameters in molecular cytogenetic and phylogenic studies, and for the progress of whole-genome sequencing. In this study, the C-value and AT content of nine abalone species inhabiting the Northwest Pacific (around Japan), Southeast Asia, South Africa, and Oceania were determined using flow cytometry. C-value ranged from 1.32 pg for Haliotis varia (Southeast Asia) to 2.01 pg for Haliotis laevigata (Oceania), and AT content ranged from 58.0% for Haliotis planata (Southeast Asia) to 66.3% for Haliotis diversicolor aquatilis (Southeast Asia). Reported chromosome numbers ranged from 2n = 32 to 36, and were higher in Oceanian, South African, and Northwest Pacific species (2n = 36) compared with the Southeast Asian group (2n = 32). This increase of chromosome number in the Oceanian species seems to be related to an increase in the DNA amount, unlike that of Haliotis midae (South African species). An increase of the C-value associated with an increase in DNA amount was also shown in the North Pacific group. These results suggest that increases in the DNA amount occurred independently in the ancestor of each of the different lineages.
Improved reproductive performance of tiger tail seahorse, Hippocampus comes, by mysid shrimp fed singly or in combination with other natural food The brood size, parturition frequency and parturition occurrence of tiger tail seahorse, Hippocampus comes were evaluated for 180 days using single and combined diets comprising Artemia salina, mysid shrimp Mesopodopsis orientalis and frozen Acetes sp. The daily food intake of seahorse was determined with the following treatments: T1-Artemia; T2-mysid; T3-Acetes; T4-Artemia + mysid; T5-Artemia + Acetes ; T6-mysid + Acetes; and T7-Artemia + mysid + Acetes. Percent body weight (% BW) of daily food intake until satiation was similar in Artemia, mysid and Artemia + Acetes (20-22 %), but significantly higher in mysid + Acetes, Artemia + mysid, and Artemia + mysid + Acetes with 25, 31 and 33 %, respectively (p < 0.05). Single diet of frozen Acetes was least consumed at 6 %. Thus, mysid was the preferred food of adult seahorses as a single or combined diet with Artemia and Acetes. Diet treatments with single mysid or combined with Artemia and Acetes have significantly higher brood size (223-292) than the other treatments (107-152) (p < 0.05). Significantly longer parturition interval (60 days) was observed in seahorses fed with Artemia than those fed with mysid or in combination with other natural food (13-26 days), but not significantly different to seahorses fed with Acetes and Artemia + Acetes (42-45 days). Parturition occurrence in seahorse fed with Artemia, Acetes and Artemia + Acetes (2.7-4.3) were the lowest, while Artemia + mysid and Artemia + mysid + Acetes have significantly higher occurrence followed by mysids + Acetes and mysid only (p < 0.05). Thus, the reproductive performance was improved when seahorses were fed with single or combined foods including mysid. Total lipid was positively correlated to brood size and parturition occurrence, while DHA:EPA ratio was negatively correlated to brood size and parturition occurrence.
Microsatellite–centromere mapping in the Japanese eel (Anguilla japonica) by half-tetrad analysis using induced triploid families Genetic improvement of the Japanese eel (Anguilla japonica) can be achieved by artificially controlling its life cycle using recent advances in reproductive biology. In this study, we developed 43 microsatellite loci to confirm Mendelian inheritance at 10 of them as well at 16 previously reported in two full-sib families produced by artificial insemination. In order to establish a base for aquaculture genetics of this species in the near future, these microsatellite loci were mapped in relation to the centromere by half-tetrad analysis using four artificially induced triploid families. The second division segregation frequency (y) of the microsatellite loci ranged from 0.008 to 0.968 (mean ± SD = 0.645 ± 0.298). These results suggest the presence of strong chiasma interference in the eel. Significant differences were observed for the map distances of microsatellite loci between the two isolation procedures. Microsatellites isolated using the enrichment procedure were mapped to various sites starting from the centromere to the telomere, whereas those from the conventional size-selected library showed a tendency to be distributed in the telomeric region.