Comprehensive characterization of yam tuber nutrition and medicinal quality of Dioscorea opposita and D.alata from different geographic groups in China

China is an important domestication center of yams,and two main yam species of Dioscorea opposita and D.alata are commonly cultivated in China.However,the differences of nutritional and medicinal characteristics between the two species and their subgroups remain unclear,which would greatly affect the resource conservation and commercial utilization of yams.In this study,typical yam resources including the species of D.opposita(wild and cultivated Ruichang yam from southern China,and Tiegun yam from northern China)and two landraces of D.alata(Longyan yam and Anyuan yam from southern China)were selected as materials.Nutritional traits and medicinal characteristics were determined and analyzed respectively.The results showed that there was no significant differences in the content of most nutrients between D.opposita and D.alata,but most cultivated Ruichang yam of D.opposita showed higher levels of starch,soluble sugar,sucrose,and ascorbate in tuber than that in yam from D.alata.Moreover,an UPLC-MS method was developed for identification and determination of medicinal characteristics in the two species.The results showed that allantoin can be detected in all selected samples.Cultivated Ruichang yam of D.opposita possessed the highest allantoin content among the tested materials,and was significantly different with that in Tiegun yam and D.alata.Dioscin was not detected in D.alata.Overall,there was little difference in nutritional composition between D.opposita and D.alata,but the medicinal quality of D.opposita was better than that of D.alata.Due to the outstanding comprehensive quality,the local variety of cultivated Ruichang yam can be further developed and utilized.

Otolith Shape Analysis as a Tool to Identify Two Pacific Saury(Cololabis saira) Groups from a Mixed Stock in the High-Seas Fishing Ground

The Pacific saury Cololabis saira is a commercially important pelagic species with wide distribution in the North Pacific Ocean. Previous studies identified two geographical groups by comparing the radius of otolith annual rings(ROA) of the fish collected during the pre-fishing season. Moreover, understanding the group composition in the mixed catch from the fishing ground is essential for sustainable exploitation of this species. Using samples collected during the fishing season(July–November) from 2016 to 2018, the potential of applying otolith shape analysis as a tool to identify these two mixed groups was tested in this research. Two otolith morphotypes that belong to the eastern group and western group were identified by K-means cluster analysis using Fourier coefficients and ROA. The high classification success of random forest further confirmed the effectiveness of otolith shape analysis. The western group accounted for the majority of catch in July and August at 160?E. With the passing of sampling time and fishing fleets moving westward, the proportion of eastern group gradually increased and finally reached more than 60% of the whole catch in November at 150°E. This result suggests that the eastern and western groups are well mixed during spawning migration. In addition, the temporal and spatial dynamics of their catch composition provide information for their migration route. This study is helpful for improving fisheries management and understanding the short-term stock fluctuation of Pacific saury.