No abstract

Seaweeds are essential for marine ecosystems and have immense economic value. Here we present a comprehensive analysis of the draft genome of Saccharina japonica, one of the most economically important seaweeds. The 537-Mb assembled genomic sequence covered 98.5% of the estimated genome, and 18,733 protein-coding genes are predicted and annotated. Gene families related to cell wall synthesis, halogen concentration, development and defence systems were expanded. Functional diversification of the mannuronan C-5-epimerase and haloperoxidase gene families provides insight into the evolutionary adaptation of polysaccharide biosynthesis and iodine antioxidation. Additional sequencing of seven cultivars and nine wild individuals reveal that the genetic diversity within wild populations is greater than among cultivars. All of the cultivars are descendants of a wild S. japonica accession showing limited admixture with S. longissima. This study represents an important advance toward improving yields and economic traits in Saccharina and provides an invaluable resource for plant genome studies.

Extracellular vesicles (EVs) carry signals within or at their limiting membranes, providing a mechanism by which cells can exchange more complex information than what was previously thought. In addition to mRNAs and microRNAs, there are DNA fragments in EVs. Solexa sequencing indicated the presence of at least 16434 genomic DNA (gDNA) fragments in the EVs from human plasma. Immunofluorescence study showed direct evidence that acridine orange-stained EV DNAs could be transferred into the cells and localize to and inside the nuclear membrane. However, whether the transferred EV DNAs are functional or not is not clear. We found that EV gDNAs could be homologously or heterologously transferred from donor cells to recipient cells, and increase gDNA-coding mRNA, protein expression, and function (e.g. AT1 receptor). An endogenous promoter of the AT1 receptor, NF-κB, could be recruited to the transferred DNAs in the nucleus, and increase the transcription of AT1 receptor in the recipient cells. Moreover, the transferred EV gDNAs have pathophysiological significance. BCR/ABL hybrid gene, involved in the pathogenesis of chronic myeloid leukemia, could be transferred from K562 EVs to HEK293 cells or neutrophils. Our present study shows that the gDNAs transferred from EVs to cells have physiological significance, not only to increase the gDNA-coding mRNA and protein levels, but also to influence function in recipient cells.