Deletion and tandem duplications of biosynthetic genes drive the diversity of triterpenoids in Aralia elata.

Araliaceae species produce various classes of triterpene and triterpenoid saponins, such as the oleanane-type triterpenoids in Aralia species and dammarane-type saponins in Panax, valued for their medicinal properties. The lack of genome sequences of Panax relatives has hindered mechanistic insight into the divergence of triterpene saponins in Araliaceae. Here, we report a chromosome-level genome of Aralia elata with a total length of 1.05 Gb. The loss of 12 exons in the dammarenediol synthase (DDS)-encoding gene in A. elata after divergence from Panax might have caused the lack of dammarane-type saponin production, and a complementation assay shows that overexpression of the PgDDS gene from Panax ginseng in callus of A. elata recovers the accumulation of dammarane-type saponins. Tandem duplication events of triterpene biosynthetic genes are common in the A. elata genome, especially for AeCYP72As, AeCSLMs, and AeUGT73s, which function as tailoring enzymes of oleanane-type saponins and aralosides. More than 13 aralosides are de novo synthesized in Saccharomyces cerevisiae by overexpression of these genes in combination. This study sheds light on the diversity of saponins biosynthetic pathway in Araliaceae and will facilitate heterologous bioproduction of aralosides.

More Depression-Related Public Concern After the Suicide of a Pop Star in China: Evidence From the Online Big Data Platform.

Background: In China, we have seen dramatic increases in public concern over depression and mental health after the suicide of some famous persons. The objective of this study is to investigate the changes of search-engine query patterns to monitor this phenomenon based on the tragic suicide of a young Chinese pop star, Kimi Qiao. Methods: The daily search volume for depression was retrieved from both the Baidu Index (BDI) and the Sina MicroBlog Index (SMI). Besides, the daily BDI for suicide, schizophrenia, obsessive-compulsive disorder, common cold, stomach cancer, and liver cancer were collected for comparison. According to the time of Qiao's suicide, all data were divided into two periods (i.e., Period One from 1 September 2015 to 31 August 2016 while Period Two ranged from 1 October 2016 to 30 September 2017). The paired t-test was used to compare the differences in search volumes between two periods. The Pearson correlation analysis was used to estimate correlations between the BDI and SMI for depression. Results: The average BDI for depression, BDI for suicide, and SMI for depression in Period Two were significantly higher than in Period One (p < 0.05). There was a strong positive correlation between the BDI and SMI for depression (r = 0.97, p < 0.001). And no significant difference in BDI for other diseases between the two periods was found. Conclusions: The changes of search-engine query patterns indicated that the celebrity's suicide might be able to improve the netizens' concern about depression in China. The study suggests publishing more practical knowledge and advice on depression through the Internet and social media, to improve the public's mental health literacy and help people to cope with their depressive symptoms appropriately.

Polarized Distribution of Active Myosin II Regulates Directional Migration of Cultured Olfactory Ensheathing Cells.

Migration of olfactory ensheathing cells (OECs) is critical for development of olfactory system and essential for neural regeneration after OEC transplantation into nerve injury site. However, the molecular mechanisms underlying the regulation of directional migration of OECs remain unclear. In this study, we found that in migrating OECs, phosphorylated myosin light chain (p-MLC, active myosin II) displayed a polarized distribution, with the leading front exhibiting higher than soma and trailing process. Over-expression of GFP-MLC significantly reduced OEC migration. Moreover, decreasing this front-to-rear difference of myosin II activity by the frontal application of a ML-7 (myosin II inhibitors) gradient induced the collapse of leading front and reversed soma translocation of OECs, whereas, increasing this front-to-rear difference of myosin II activity by the rear application of a ML-7 or BDM gradient or the frontal application of a Caly (myosin II activator) gradient accelerated the soma translocation of OECs. Finally, myosin II as a downstream signaling of repulsive factor Slit-2 mediated the reversal of soma translocation induced by Slit-2. Taken together, these results suggest that the polarized distribution of active myosin II regulates the directional migration of OECs during spontaneous migration or upon to extracellular stimulation such as Slit-2.