1H NMR based metabolic profiling in the evaluation of Japanese green tea quality

Classification of tea quality is now mainly performed according to the sensory results by professional tea tasters. However, this evaluation method is inconsistent in differentiating their qualities. A combination of a (1)H NMR technique and a multivariate analysis was introduced to the quality evaluation of green tea by means of a metabolomic technique. A broad range of metabolites were detected by (1)H NMR spectrometry. The principal component analysis (PCA) was used to reduce the complexity of the (1)H NMR spectra data set and provided the quality discrimination result. It offered an extensive clue for classification and quality assessment without any prepurification method. A set of green teas from a Japanese tea contest were analyzed by (1)H NMR to classify the quality with respect to that judged by tea tasters and to conceive a quality prediction model. Metabolic profiling and fingerprinting of (1)H NMR spectra of green teas with different quality were studied. PCA showed a separation between the high- and the low-quality green teas. The taste marker compounds contributing to the discrimination of tea quality were identified. Reliable prediction models were obtained by the partial least-squares projection to latent structure (PLS) analysis together with a preprocessing filter of both orthogonal signal correction (OSC) and a combination between OSC and wavelet transform algorithms.     

Spontaneous polyploidization in critically endangered <Emphasis Type="Italic">Acipenser mikadoi</Emphasis>

We investigated the source of spontaneous polyploidization in the critically endangered Acipenser mikadoi. Fourteen sib progeny of A. mikadoi and 11 hybrids between an A. mikadoi female and a Huso dauricus male, all showing atypically high ploidy, were analysed. Parent assignment based on five highly polymorphic microsatellite markers confirmed spontaneous duplication of maternal chromosome sets via retention of the second polar body to be the source of spontaneous polyploidization. To our knowledge, this provides the first evidence of the maternal origin of spontaneous polyploidization in A. mikadoi. Factorial correspondence analysis of the multilocus microsatellite genotypes placed the parent fish of spontaneous polyploids in clearly delineated clusters of A. mikadoi and H. dauricus, and parent fish had mitochondrial control region haplotypes corresponding to their presumed species. Thus, parent fish were confirmed to be of pure genetic origin, and hybridization did not promote the observed spontaneous polyploidization.     

Monitoring of chronic wasting disease using real-time quaking-induced conversion assay in Japan

There has been no report on Chronic wasting disease (CWD) cases in Japan to date; however, there is concern about the geographic spread of CWD. To clarify the CWD status in Japan, we conducted CWD monitoring using real-time quaking-induced conversion (RT-QuIC) assay which can detect the low level of CWD prions. A total of 690 obex samples collected from sika deer and Reeves’s muntjac in Hokkaido and Honshu was tested for CWD prions. No CWD-positive cases were found, suggesting that CWD is nonexistent in Japan. Our results also indicate that RT-QuIC assay is useful for continuous monitoring of CWD. Furthermore, nucleotide sequence analysis of the PrP gene revealed sika deer in Japan harbor CWD susceptible allele.