Olive flounder, Paralichthys olivaceus, is an important fish species in Asia, both for fisheries and aquaculture. As the first step for better understanding the genomic structure and functional analysis, we constructed a genetic linkage map for olive flounder based on 180 microsatellites and 31 expressed sequence tag (EST)-derived markers. Twenty-four linkage groups were identified, consistent with the 24 chromosomes of this species. The total map distance was 1,001.3 cM based on Kosambi sex-average mapping, and the average inter-locus distance was 4.7 cM. Linkage between the loci was identified by an LOD score of ≥3. This linkage map may be used to map quantitative trait loci associated with important traits of the species and may assist in breeding programs.

A highly self-healable polymeric system with enhanced mechanical properties is prepared by blending conventional polyurethane (PU) with functional polyimide (PI). PU and PI synthesized in this study are miscible with each other and the thermal stability of the self-healable blend (PUPI) is improved by incorporation of PI into PU. Interestingly, on adding only a small amount of PI to PU, PUPI exhibits higher self-healing efficiency and faster self-healing kinetics. Furthermore, unlike conventional self-healing materials, PUPI also has superior surface and bulk mechanical properties. A model for the mechanism for the improvement of self-healing and mechanical properties is derived by analyzing FT-IR spectra. The outstanding self-healing and mechanical properties are attributed to the unique intermolecular networks resulting from the strong supramolecular interactions between urethane groups in PU and imide groups in PI. As a result, the PI chain acts as a polymeric glue inside the PU matrix of PUPI, which results in significant enhancements in both properties mentioned previously.

No abstract

Variation within the growth hormone gene and its association with growth trait in the olive flounder (Paralichthys olivaceus) was investigated. Based on Southern blot analysis and using various kinds of restriction endonucleases, it was demonstrated that the growth hormone gene exists as a single copy gene in the olive flounder. Polymorphisms of various lengths were also detected by Southern blot analysis, and by the subsequent digestion of the polymerase chain reaction (PCR) ‐amplified growth hormone gene fragment with Sau3AI restriction enzyme. To study the possible association between variation in the growth hormone and weight, 60 progenies of the hatchery strain of three various sizes (large, medium and small weight) were selected and the entire genetic structure of the growth hormone gene was analysed. A total of 15 different genotypes was observed from the random association of six haplotypes. Significant heterogeneity of the growth hormone gene with haplotype and genotype frequencies was detected among the different‐sized groups.

The mottled skate, Raja pulchra, is an economically valuable fish. However, due to a severe population decline, it is listed as a vulnerable species by the International Union for Conservation of Nature. To analyze its genetic structure and diversity, microsatellite markers were developed using 454 pyrosequencing. A total of 17,033 reads containing dinucleotide microsatellite repeat units (mean, 487 base pairs) were identified from 453,549 reads. Among 32 loci containing more than nine repeat units, 20 primer sets (62%) produced strong PCR products, of which 14 were polymorphic. In an analysis of 60 individuals from two R. pulchra populations, the number of alleles per locus ranged from 1–10, and the mean allelic richness was 4.7. No linkage disequilibrium was found between any pair of loci, indicating that the markers were independent. The Hardy–Weinberg equilibrium test showed significant deviation in two of the 28 single-loci after sequential Bonferroni’s correction. Using 11 primer sets, cross-species amplification was demonstrated in nine related species from four families within two classes. Among the 11 loci amplified from three other Rajidae family species; three loci were polymorphic. A monomorphic locus was amplified in all three Rajidae family species and the Dasyatidae family. Two Rajidae polymorphic loci amplified monomorphic target DNAs in four species belonging to the Carcharhiniformes class, and another was polymorphic in two Carcharhiniformes species.

For the ¢rst generation of a selective breeding programme, it is important to minimize the possibility of inbreeding. This mostly occurs by mating between closely related individuals, while proper mating can provide an opportunity to establish the base families with wide genetic variation from which selection for subsequent generations can be more e¡ective. Genotyping with microsatellite-based DNA markers can help us determine the genetic distances between the base populations. The genetic markers further facilitate the identi¢cation of the correct parents of the o¡spring (parentage assignments) reared together with many other families after hatching. We established a genetic analysis system with microsatellite DNA markers and analysed the genetic distances of three farmed stocks and a group of ¢sh collected from wild populations using eight microsatellite markers. The averaged heterozygosity of the farming stocks was 0.826 and that of the wild population was 0.868. The hatchery strains had an average of 8.6 alleles per marker, which was less than a wild population that carried an average of 14.3 alleles per marker. Signi¢cant Hardy^Weinberg disequilibrium (HWDE) was observed in two farming stocks (Po0.05). Despite relatively low inbreeding coe⁄ciency of the hatchery populations, the frequency of a few alleles was highly represented over others. It suggests that the hatchery stocks to some extent have experienced inbreeding or they originated from closely related individuals. We will develop a selective program using the DNA mar-kers and will widen the usage of the DNA-based genetic analysis system to other ¢sh species.

No abstract

Background: Signal transducer and activator of transcription 1 (STAT1) is a critical component of interferon (IFN)-alpha/beta and IFN-gamma signaling. Although seven isoforms of STAT proteins have been reported from mammals, limited information is available for the STAT genes in fish. We isolated complementary DNA with high similarity to mammalian STAT1 from the olive flounder, Paralichthys olivaceus.