DNA analyses are required for food labeling regulation to differentiate commercially important fishery products, because many of the distinguishing morphological features are no longer identifiable after food processing. In Japan, the Law Concerning Standardization and Proper Labeling of Agricultural and Forestry Products (JAS Law) of revision in 1999 has been establishing quality labeling standards for almost of foods and beverages. In perishable foods, "Name of the food" and "Country of origin" must appear on the food label. In processed foods, "Name", "Names of ingredients", "Net contents", etc. must appear on the food label. The DNA-based genetic methods for species and product identification are very important to certify correct food labeling in the market places. Several fishery products have been investigated to develop the DNA-based analytical methods for examining the authentication of species name and origin identification. We introduce the species identification methods for tuna, horse mackerel, mackerel, cod roe, and yellowtail-related species.

The trace element contents of Corbicula clam shells collected from Japan, Russia, China, and the Republic of Korea were analyzed to determine their geographic origin. The crushed shells were decomposed with nitric acid–hydrogen peroxide, and the concentrations of 14 elements (Li, Mg, V, Mn, Co, As, Rb, Mo, Ba, Ce, Pb, U, Sr, and Ca) were measured by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry. Some of the elements identified in samples displayed a geographic trend. The average content of manganese in Japanese samples was twice that of Russian samples. Conversely, the arsenic content in Japanese samples was approximately half of that in Russian samples. Linear discriminant analysis was applied to the data from Japanese and Russian samples, and a discriminant model was constructed. The discriminant model was used to determine the geographic origin of Corbicula clams produced in Japan, with 89.8 % of those identified as Japanese and 92.2 % of those identified as Russian being classified correctly. Therefore, trace element analysis of the shells of Corbicula clams is a useful technique for the identification of their country of origin.

Nucleotide sequences in internal transcribed spacer (ITS)-1 region derived from dried nori products produced in Japan, China, and the Republic of Korea were compared. Thalli contained in the Japanese products were genetically homogenous, and their nucleotide sequences in ITS-1 were identical to those of the reference strains of Pyropia yezoensis f. narawaensis. In Chinese products, the thalli were related to P. yezoensis strain Minomiasakusa. In contrast, the thalli in the Korean products were genetically heterogeneous, and several different P. yezoensis strains and other Pyropia spp. were used for dried nori products. In some thalli produced in both China and Korea, the DNA sequences of the ITS-1 region were identical with that of Japan, suggesting that the cultivar strains might have been transplanted from Japan to China in recent years. The 432-bp-long nucleotide sequences in the ITS-1 region of thalli derived from Japanese origin were cleaved to two restriction fragments at 154 and 278 bp by cleavage of PCR-amplified products using MspI. Conversely, almost all of the corresponding sequences derived from China and Korea were lacking MspI or other restriction patterns, except for nori products from some areas that cultivate a closely related strain to the Japanese cultivar.

The correlations among the contents of trace elements in the shells of short-neck clams collected from Japan, China, and the Republic of Korea were examined. Origin-specific elemental content patterns were seen in clams originating from Japan, China, and the Republic of Korea. The crushed shells were decomposed with nitric acid–hydrogen peroxide, and the concentrations of ten elements (Li, V, Mn, Co, As, Rb, Mo, Ba, Pb, and U) in the shells were measured by inductively coupled plasma mass spectrometry. Some of the metal concentrations in the samples displayed clear geographical trends. The average concentration of Pb in Japanese clam shells was one-half to one-quarter that seen in Chinese or Korean clams. Average concentrations of As, Rb, and Ba in shells of Japanese origin were one-half those observed in Chinese or Korean clams. Linear discriminant analysis was applied to these analytical data, and four discriminant models were constructed. These discriminant models were able to distinguish the geographic origins of short-neck clams with 80.0–100 % accuracy. In particular, clams of Japanese origin were classified correctly ≥90 % of the time. Therefore, the trace elemental analysis of a short-neck clam shell is useful for identifying the country of origin of the clam.

Trace elemental composition in intermuscular bones of grilled eel fillets was analyzed to discriminate the geographic origin of eel products derived from Japan, China, and Taiwan. The intermuscular bones were decomposed with nitric acid-hydrogen peroxide, and twelve elements (Li, Ti, V, Mn, Ni, Co, Zn, Rb, Sr, Ba, Pb, and U) were analyzed by inductively coupled plasma mass spectrometry. Trace elemental composition including six elements: V, Co, Sr, Ba, Pb, and U, in intermusucular bones were significantly different between Japanese domestic eels and imported eels from China and Taiwan. The average content of lead in Japanese eels was 1/4 to 1/6 that in eels imported from China and Taiwan. The data of elemental content in intermuscular bones were used for linear discriminant analysis, and two discriminant models were constructed. In the Japan–China discriminant model, the discriminant probabilities between Japanese origin and Chinese origin were 82.5 and 93.3 %, respectively. In the Japan–Taiwan discriminant model, the discriminant probabilities between Japanese origin and Taiwanese origin were 87.5 and 87.0 %, respectively. Therefore, trace elemental analysis is effective for country-of-origin identification of eels processed as grilled eel fillets.

The complete nucleotide sequences of mitochondrial DNA (mtDNA) from four Seriola spp. (S. quinqueradiata, S. lalandi, S. dumerili, and S. rivoliana) were determined with the aim of developing a species identification analysis method for discriminating between commercially important Seriola spp. and other related species. In addition, the nucleotide sequences of the mitochondrial cytochrome b gene (Cytb) from five related but less expensive species in terms of market value (Seriolella brama, S. caerulea, S. punctata, Hyperoglyphe japonica, and Rachycentron canadum), which are often used as substitutes for Seriola spp., were determined. Restriction enzyme sites were examined by comparing the nucleotide sequences, and species-specific primers were designed for PCR-based restriction fragment length polymorphism (RFLP) analysis. Based on the results of the PCR amplification studies, the four Seriola spp. and the five related species tested could be categorized into three groups according to their PCR product pattern: a 373-bp product from the four Seriola spp., a 513-bp product from three Seriolella spp. and H. japonica, and a 204-bp product from R. canadum. In addition, RFLP analysis of the PCR products was able to differentiate these fish species.

Fish species identification techniques for authentic food labeling were developed using species-specific PCR primers for cod roe products. A salted, seasoned fish roe product, karashimentaiko (chilli cod roe), is produced from the eggs of Alaska pollock, Theragra chalcogramma, according to the fair trade competition agreement authorized by the Fair Trade Commission of the Japanese government. To examine whether Alaska pollock ovaries or those of other fish species are being used as raw materials for the fish roe products, we developed species identification techniques using PCR amplification of a 255-bp fragment encoding the mitochondrial ATP synthase Fo subunit 6 (ATP6) gene with a species-specific primer set for Alaska pollock mitochondrial DNA. We also designed two species-specific primer sets corresponding to the mitochondrial ATP6 and cytochrome b (cytb) for Gadus spp. and Micromesistius spp. by PCR amplification of 332- and 223-bp fragments, respectively. We examined the species specificity of these PCR-based methods among nine commercially important Gadidae species.

Nitrate levels were determined by jon chromatography for 1094 samples of market. vegetables. The nitrate levels (mean +/- standard deviation) of the vegetables are as follows: cabbage (n = 189), 679 +/- 453 ppm ; Chinese cabbage (n = 186), 1320 +/- 669 ppm : head lettuce (n = 174), 1060 +/- 480 ppm;komatsuna (n=197), 4060 1720 ppm ; spinach (n = 208), 3070 +/- 1360 ppm : qing gin cai (n = 20), 2750 +/- 932 ppm; nozawana (n = 20), 2840 +/- 580 ppm; turnip (n = 20), root 1630 +/- 772 ppm, leaves 3540 +/- 1700 ppm; garland chrysanthemum (n=20), 2940 +/- 1110 ppm; leek (n = 20), 1780 +/- 567 ppm; takana (n = 20), 3680 +/- 1220 ppm; and ta cai (n = 20), 3340 +/- 1310 ppm.