Aquaculture is a key technology in seafood production because capture fishery production remains at the same level despite increasing demand for seafood. Thus, genetic breeding is necessary to efficiently obtain fish and shellfish products in aquaculture. Although selective breeding has been the most popular and widely used method for both plants and animals, it usually takes a long time to establish strains with desirable traits. In contrast, chromosome set manipulation and genome manipulation including transgenesis and genome editing allow expression of desirable traits for aquaculture within a comparatively short period. The former can induce polyploids and artificial parthenogenesis. Triploid fish and shellfish have been used for aquaculture due to their sterility. Sterile triploids show advantages in high flesh quality during spawning season compared to fertile diploids, and in biological containment to avoid genetic contamination of wild populations. The latter can induce individuals with desirable traits by direct alteration of the genome, such as insertion of foreign genes to obtain additional traits by transgenesis and mutation of the indigenous genome to enhance desirable traits by genome editing. Here, we review applications of polyploids in aquaculture and current topics of genome manipulation in fish genetic breeding.
Collagen peptides (CP) were extracted from scales of lizardfish (Saurida macrolepis). The CP sample contained approximately 10% each of hydroxyproline and proline. The control diet contained 10% casein as the dietary protein source, and 3% casein was replaced with CP in the CP diet. Twelve-week-old ovariectomized rats were fed the experimental diets for 11 weeks. The decrease of total bone mineral density (BMD) in the lumber spine of rats fed CP diets, and femur hardness remained unchanged. Serum Gla-osteocalcin, a marker of bone formation, was not altered in rats fed CP, while serum type I collagen cross-linked N-telopeptide, a marker of bone resorption, was significantly higher in rats fed CP diets than in those fed control diet. These results indicate that CP extracted from scales of lizardfish suppressed the structural deterioration of the lumbar spine and femur, and maintained bone strength of the femur.
The purpose of this study was to investigate the effects of two types of rice flour, with different starch damage degrees, on bread-making properties and temporal changes in bread crumb rheological properties. The subject of this study was wheat flour and rice flour blended bread, in which rice flour was used to replace 40% of the wheat flour. It was found that rice flour with a high degree of starch damage had high water retention capacity. Also, differences in the shape and surface microstructure of rice flour particles were observed. When producing the subject bread on a laboratory scale, it was found that replacing 25% or 50% of low starch damage rice flour with high starch damage rice flour reduced the temporal changes in bread crumb rheological properties compared to the product made using only rice flour with a low degree of starch damage (2.7%). With the aim of simulating mass production, the subject bread was produced on an experimental factory scale with each rice flour type at a ratio of 50% (starch damage degree 8.2%). Results showed that when the starch damage degree increased, dough hardening was suppressed and temporal changes in the rheological properties of the subject bread crumb (firmness and cohesiveness) decreased. It was speculated that as the starch damage degree increased, α-amylase, which was added during the dough mixing stage, acted more easily.
Antioxidation containers, recently used to keep soy sauce fresh, are known to preserve the color of soy sauce. However, it is unclear whether these containers also maintain the flavor of soy sauce. We evaluated the effect of these containers on the flavor compounds of soy sauce using GC/MS with solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE). The soy sauce was stored for 30 weeks in a PET bottle or two antioxidation containers, a pouch in a dispenser (PID) and a Delami bottle. SMPE-GC/MS analysis revealed that the soy sauce in the PET bottle had an increased amount of pyrazines and short-chain fatty acids and a decreased amount of esters compared with the antioxidation container samples. 2,3,5-Trimethylpyrazine was slightly increased in the Delami bottle sample than the PID sample, and a similar tendency was observed for the color change of soy sauce. Dimethyl trisulfide and nonanal were analyzed by SBSE-GC/MS to improve the stability of analytes compared with SPME. Dimethyl trisulfide and nonanal were the most significantly increased flavor compounds of soy sauce, and the increase of these compounds was reduced in the antioxidation containers.
To prevent serious insect infestation in stored food, the development of early insect detection methods is essential. At present, detection is primarily conducted using pheromone traps, which are effective only after the insects have already propagated. In our previous study, new volatile biomarkers for the detection of insects in brown rice were determined using gas chromatography-mass spectrometry (GC-MS). In the present study, we attempted to develop a rapid analytical approach for the detection of major volatile biomarkers emitted from brown rice infested with Indian meal moth, rice moth, and maize weevil by employing a real-time mass spectrometry known as selected ion flow tube mass spectrometry (SIFT-MS). With selected ion monitoring (SIM) of m/z 86 by NO＋ ionization, product ions that corresponded to prenol and isoprenol were detected from Indian meal moth-infested and rice moth-infested brown rice. The compounds were easily distinguishable from each other according to whether prenol-parallel prenal was generated. In the case of maize weevil, the target dimethyl trisulfide (DMTS) fluctuated at low levels. Nonetheless, the characteristic principal component analysis (PCA) score for maize weevil-infested brown rice could be obtained using the observed full scan data.
The antifungal activity against Botrytis cinerea, a pathogen of grape gray mold disease, was validated in vitro for 59 of 225 wild yeast strains isolated from naturally fermented wine samples (69 strains), our university campus plants (129 strains), and commercially available fruits (27 strains). Twenty strains showing strong antifungal activity were identified. The majority of the strains were Saccharomyces cerevisiae (16 of the 20 strains). The S. cerevisiae strains were differentiated by genetic polymorphism analyses with comparisons of their antifungal activities. As a result, it was clarified that each strain type showed different antifungal activity, and that automatic rRNA intergenic spacer analysis was extremely useful for the differentiation of S. cerevisiae strains when compared to other conventional polymerase chain reaction-based methods.