Glycerol-3-phosphate metabolism plays a role in stress response in the red alga Pyropia haitanensis.

Glycerol-3-phosphate (G3P) has been suggested as a novel regulator of plant defense signaling, however, its role in algal resistance remains largely unknown. The glycerol kinase (also designated as NHO1) and NAD-dependent G3P dehydrogenase (GPDH) are two key enzymes involved in the G3P biosynthesis. In our study, we cloned the full-length cDNA of NHO1 (NHO1Ph ) and GPDH (GPDHP h ) from the red alga Pyropia haitanensis (denoted as NHO1Ph and GPDHP h ) and examined their expression level under flagellin peptide 22 (flg22) stimulation or heat stress. We also measured the level of G3P and floridoside (a downstream product of G3P in P. haitanensis) under flg22 stimulation or heat stress. Both NHO1Ph and GPDHP h shared high sequence identity and structural conservation with their orthologs from different species, especially from red algae. Phylogenetic analysis showed that NHO1s and GPDHs from red algae were closely related to those from animals. Under flg22 stimulation or heat stress, the expression levels of NHO1Ph and GPDHP h were up-regulated, G3P levels increased, and the contents of floridoside decreased. But the floridoside level increased in the recovery period after heat stress. Taken together, we found that G3P metabolism was associated with the flg22-induced defense response and heat stress response in P. haitanensis, indicating the general conservation of defense response in angiosperms and algae. Furthermore, floridoside might also participate in the stress resistance of P. haitanensis.

[Chemical constituents contained in ethanol extracts from Acorus tatarinowii and their anti-fatigue activity].

Chemical constituents in ethyl acetate and butanol fractions of ethanol extracts from Acorus tatarinowii were separated by column chromatography. Bufo skeletal muscle fatigue model was established to study the anti-fatigue activity of separated compounds. Five compounds were separated and identified by spectroscopic analysis as acoramone(1),cycloartenone(2),2,4,5-trimethoxyl-2'-butoxy-1,2-phenyl propandiol(3),5-hydroxymethyl furfural(4), and 5-butoxymethyl furfural(5). Compound 3 was a new compound, and compounds 2 and 5 were separated from this plant for the first time. Compound 4 exhibited a notable anti-fatigue activity.