Epithelial cell ADAM17 activation by Helicobacter pylori: role of ADAM17 C-terminus and Threonine-735 phosphorylation

Helicobacter pylori transactivates the epidermal growth factor receptor (EGFR) on gastric epithelial cells via a signalling cascade involving a disintegrin and metalloprotease 17 (ADAM17) cleavage of membrane bound heparin binding-epidermal growth factor (HB-EGF). The effects of H. pylori on ADAM17 C-terminus in epithelial cells have been examined. Total cellular ADAM17 and surface expression of ADAM17 were significantly increased by H. pylori in AGS gastric epithelial cells. These changes were associated with ADAM17 C-terminal phosphorylation at T375 and S791. AGS cells lacking the ADAM17 C-terminal domain induced significantly attenuated cleavage of HB-EGF and were also unable to upregulate HB-EGF and EGFR transcripts to the same extent as cells expressing full length ADAM17. In mitotic unstimulated AGS and ADAM17 over-expressing AGS cells, ADAM17 was highly T735 phosphorylated indicating ADAM17 T735 phosphorylation is modified during the cell cycle. In conclusion, H. pylori induced ADAM17 C-terminal T735 and/or S791 phosphorylation in gastric epithelial cells are likely to be an important trigger inducing ADAM17 activation and shedding of HB-EGF leading to EGFR transactivation. ADAM17 over-expression in gastric cancer represents a potential target for therapeutic intervention

Environmental DNA as a ‘Snapshot’ of Fish Distribution: A Case Study of Japanese Jack Mackerel in Maizuru Bay, Sea of Japan

Recent studies in streams and ponds have demonstrated that the distribution and biomass of aquatic organisms can be estimated by detection and quantification of environmental DNA (eDNA). In more open systems such as seas, it is not evident whether eDNA can represent the distribution and biomass of aquatic organisms because various environmental factors (e.g., water flow) are expected to affect eDNA distribution and concentration. To test the relationships between the distribution of fish and eDNA, we conducted a grid survey in Maizuru Bay, Sea of Japan, and sampled surface and bottom waters while monitoring biomass of the Japanese jack mackerel (Trachurus japonicus) using echo sounder technology. A linear model showed a high R2 value (0.665) without outlier data points, and the association between estimated eDNA concentrations from the surface water samples and echo intensity was significantly positive, suggesting that the estimated spatial variation in eDNA concentration can reflect the local biomass of the jack mackerel. We also found that a bestfit model included echo intensity obtained within 10–150 m from water sampling sites, indicating that the estimated eDNA concentration most likely reflects fish biomass within 150 min the bay. Although eDNA from a wholesale fish market partially affected eDNA concentration, we conclude that eDNA generally provides a ‘snapshot’ of fish distribution and biomass in a large area. Further studies in which dynamics of eDNA under field conditions (e.g., patterns of release, degradation, and diffusion of eDNA) are taken into account will provide a better estimate of fish distribution and biomass based on eDNA

Observed fish biomass using echo sounder.

<p>Vertical bar on the cruise track (gray line) indicates local s_a values (i.e., fish biomass observed using quantitative echo sounder), which is the integrated s_v of a water column with a cross-sectional area of 1 m². This figure is depicted according to s_a extracted every 80-m intervals. Note that this figure shows a summary of field observation using echo sounder. We used s_v values rather than s_a values as index of fish biomass in regression analyses (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0149786#pone.0149786.s001" target="_blank">S1 Fig</a>).</p

Vertical distributions of echo intensity and the sea bottom.

<p>a, data from all research areas; b, data within 150 m of St. 2; c, data within 150 m of St. 27. Bars indicate the mean echo intensity (the average of s_v) of each depth interval. Dashed lines indicate frequency distribution of water depth. Number below station names indicates the mean water depth.</p

Correlation coefficient between eDNA concentration in surface and bottom waters.

<p>Y-axis indicates vertical distance between surface- and bottom-sampling positions, i.e., the coefficient value of the class of 3.5–8.5 m was calculated using samples obtained at stations where water depth is 3.5–8.5 m. Correlation coefficient was relatively high when using samples from shallower stations, while it was low when using samples from deeper stations. This figure was depicted based on eDNA concentrations of filter series 1.</p