The biological formation of a potent flavor compound, 2-acetyl-1-pyrroline, in the aromatic rice variety (Khao Dawk Mali 105) was studied in seedlings and callus of the rice. Concentrations of 2-acetyl-1-pyrroline were determined by GC-MS-SIM using an isotope dilution method. Increases in concentration occurred when proline, ornithine, and glutamate were present in solution, with proline increasing the concentration by more than 3-fold compared to that of the control. Results of tracer experiments using (15)N-proline, (15)N-glycine, and proline-1-(13)C indicated that the nitrogen source of 2-acetyl-1-pyrroline was proline, whereas the carbon source of the acetyl group was not the carboxyl group of proline. 2-acetyl-1-pyrroline was formed in the aromatic rice at temperatures below that of thermal generation in bread baking, and formed in the aerial part of aromatic rice from proline as the nitrogen precursor.

Summary2-Acetyl-1-pyrroline (2AP), the volatile compound that provides the 'popcorn-like' aroma in a large variety of cereal and food products, is widely found in nature. Deficiency in amino aldehyde dehydrogenase (AMADH) was previously shown to be the likely cause of 2AP biosynthesis in rice (Oryza sativa L.). In this study, the validity of this mechanism was investigated in soybeans (Glycine max L.). An assay of AMADH activity in soybeans revealed that the aromatic soybean, which contains 2AP, also lacked AMADH enzyme activity. Two genes, GmAMADH1 and GmAMADH2, which are homologous to the rice Os2AP gene that encodes AMADH, were characterized.The transcription level of GmAMADH2 was lower in aromatic varieties than in nonaromatic varieties, whereas the expression of GmAMADH1 did not differ. A double nucleotide (TT) deletion was found in exon 10 of GmAMADH2 in all aromatic varieties. This variation caused a frame-shift mutation and a premature stop codon. Suppression of GmAMADH2 by introduction of a GmAMADH2-RNAi construct into the calli of the two nonaromatic wild-type varieties inhibited the synthesis of AMADH and induced the biosynthesis of 2AP. These results suggest that deficiency in the GmAMADH2 product, AMADH, plays a similar role in soybean as in rice, which is to promote 2AP biosynthesis. This phenomenon might be a conserved mechanism among plant species.

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fat acidity of rice was increased during storage and inversely correlated with 2-acetyl-1-pyrroline content at an fat acidity of rice was increased during storage and inversely correlated with 2-acetyl-1-pyrroline content at an fat acidity of rice was increased during storage and inversely correlated with 2-acetyl-1-pyrroline content at an fat acidity of rice was increased during storage and inversely correlated with 2-acetyl-1-pyrroline content at an fat acidity of rice was increased during storage and inversely correlated with 2-acetyl-1-pyrroline content at an early stage of storage. The difference in 2-acetyl-1-pyrroline recovery from the samples, which were extracted with early stage of storage. The difference in 2-acetyl-1-pyrroline recovery from the samples, which were extracted with early stage of storage. The difference in 2-acetyl-1-pyrroline recovery from the samples, which were extracted with early stage of storage. The difference in 2-acetyl-1-pyrroline recovery from the samples, which were extracted with early stage of storage. The difference in 2-acetyl-1-pyrroline recovery from the samples, which were extracted with ethanol at 40 °C and 75 °C, revealed that the starch bound and free forms of 2-acetyl-1-pyrroline may occur in ethanol at 40 °C and 75 °C, revealed that the starch bound and free forms of 2-acetyl-1-pyrroline may occur in ethanol at 40 °C and 75 °C, revealed that the starch bound and free forms of 2-acetyl-1-pyrroline may occur in ethanol at 40 °C and 75 °C, revealed that the starch bound and free forms of 2-acetyl-1-pyrroline may occur in ethanol at 40 °C and 75 °C, revealed that the starch bound and free forms of 2-acetyl-1-pyrroline may occur in aromatic rice. These results suggested that the biosynthesis of 2-acetyl-1-pyrroline before starch structure formation aromatic rice. These results suggested that the biosynthesis of 2-acetyl-1-pyrroline before starch structure formation aromatic rice. These results suggested that the biosynthesis of 2-acetyl-1-pyrroline before starch structure formation aromatic rice. These results suggested that the biosynthesis of 2-acetyl-1-pyrroline before starch structure formation aromatic rice. These results suggested that the biosynthesis of 2-acetyl-1-pyrroline before starch structure formation in rice kernel could play a key role in the aroma quality of aromatic rice. in rice kernel could play a key role in the aroma quality of aromatic rice. in rice kernel could play a key role in the aroma quality of aromatic rice. in rice kernel could play a key role in the aroma quality of aromatic rice. in rice kernel could play a key role in the aroma quality of aromatic rice.

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Lipid peroxidation induced by oxidative stress is a consequence of the production of excess free radicals, such as reactive oxygen species, and provides marked damage to the structure and function of cell membranes in various tissues.1,2) Particularly, the brain is susceptible to free radical insults because it contains a high concentration of easily peroxidizable polyunsaturated fatty acids, and is not particularly enriched in protective antioxidant enzymes or other antioxidant compounds.

The significant differences in DNA methylation that are considered to be a biomarker for the diagnosis of cancer are a barrier to the application of biomarkers in the clinical field. In the present study, new primers were designed and further standard controls were set up to validate the accuracy of the methylation‑specific PCR (MSP), a method widely used to analyze DNA methylation. By analyzing the methylation pattern of breast cancer 1 (BRCA1) and estrogen receptor (ER) in 60 patients with breast cancer, the number of cases of methylated BRCA1 and ER detected by the primer was 7/60 and 21/60, respectively, whereas that detected by the previous widely used primers was 25/60 and 47/60, respectively. Sequencing of the MSP products indicated that the 18 and 26 false-positive methylations of BRCA1 and ER, respectively, were due to insufficient validation of the previously used primers. Thus, the present study proposes that all studies based on the MSP approach should incorporate more controls to validate the precision of the MSP primers.

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