Description: A newly identified large-scale submarine landslide on the NW African margin (Agadir Slide) is investigated in terms of its morphology, internal architecture, timing, and emplacement processes using high-resolution multibeam bathymetry data, 2D seismic profiles, and gravity cores. The Agadir Slide is located south of the Agadir Canyon at a water depth ranging from 500 m to 3,500 m, showing an estimated affected area of approximately 5,500 km2. The analysis of the Agadir Slide's complex morphology reveals the presence of two headwall areas and two slide fairways (the Western and Central slide fairways). Volume calculations indicate that ∼340 km3 of sediment were accumulated downslope along the slide fairways (∼270 km3) and inside the Agadir Canyon (∼70 km3). Stratigraphic correlations based on five gravity cores indicate an emplacement age of 142±1 ka for the Agadir Slide. However, its emplacement dynamics suggest that the slide was developed in two distinct, successive stages. The presence of two weak layers (glide planes) is a major preconditioning factor for the occurrence of slope instability in the study area, and local seismicity related to fault activity and halokinesis likely triggered the Agadir Slide. Importantly, the Agadir Slide neither disintegrated into sediment blocks nor was transformed into turbidity currents. The emplacement timing of the Agadir Slide does not correlate with any turbidites cored downslope across the Moroccan Turbidite System.

Description: The seasonal and spatial variation of the suspended sediment concentration (SSC) in the Yellow Sea and the East China Sea (YSECS) is studied using turbidity, temperature and velocity field data from all seasons of 2011. The important hydrodynamic factors affecting the SSC distribution are discussed, based on the field data. The data provide a picture of the seasonal evolution of the SSC in the YSECS in a single year. The results show that the highest surface layer SSC was measured in spring and winter, while the summer had the lowest surface layer SSC. In the bottom layer, the SSC distribution patterns were similar in all seasons except that a much higher SSC water plume extended from the Subei Shoal to the East China Sea shelf in winter survey. The vertical SSC gradient was stronger in the shallow water area than the deep water area, and it was stronger in summer and autumn than in winter and spring. We argue that wind-induced vertical mixing dominated the SSC distribution in the surface layer while the tidal currents played an important role in the bottom layer and sub-tidal currents dominated the horizontal pattern of the SSC distribution pattern over the shelf area. In particular, the presence of the summer thermocline limited the vertical mixing in summer, decreasing the SSC in the surface layer. The front between the East China Sea Coastal Current and the Taiwan Warm Current appears to prevent the high SSC water from being transported to the shelf. The sediment discharged by the Changjiang River was found to be concentrated in the estuary area and influenced the shelf SSC distribution only through the action of the subtidal currents.

Description: Highlights • The upper headwall region of Sahara Slide is mapped for the first time. • The upper headwall region comprises multiple slope failures. • Slope failure occurred on pronounced glide planes at different stratigraphic levels. • Failure is young (~ 2 ka) contradicting the hypotheses of a relatively stable continental margin at present. • This young age requires a reassessment of slope instability and associated risks off NW Africa. Abstract The Sahara Slide Complex in Northwest Africa is a giant submarine landslide with an estimated run-out length of ~ 900 km. We present newly acquired high-resolution multibeam bathymetry, sidescan sonar, and sub-bottom profiler data to investigate the seafloor morphology, sediment dynamics and the timing of formation of the upper headwall area of the Sahara Slide Complex. The data reveal a ~ 35 km-wide upper headwall opening towards the northwest with multiple slide scarps, glide planes, plateaus, lobes, slide blocks and slide debris. The slide scarps in the study area are formed by retrogressive failure events, which resulted in two types of mass movements, translational sliding and spreading. Three different glide planes (GP I, II, and III) can be distinguished approximately 100 m, 50 m and 20 m below the seafloor. These glide planes are widespread and suggest failure along pronounced, continuous weak layers. Our new data suggest an age of only about 2 ka for the failure of the upper headwall area, a date much younger than derived for the landslide deposits on the lower reaches of the Sahara Slide Complex, which are dated at 50–60 ka. The young age of the failure contradicts the postulate of a stable slope off Northwest Africa during times of relative stable sea-level highstands. Such an observation suggests that submarine-landslide risk along the continental margin of Northwest Africa should be reassessed based on a robust dating of proximal and distal slope failures.

Description: Euphorkanlide A (1), a highly modified ingenane diterpenoid with a C24 appendage forming an additional hexahydroisobenzofuran-fused 19-membered macrocyclic bis-lactone ring system was isolated from the roots of Euphorbia kansuensis. Its structure was determined by extensive spectroscopic analysis and quantum-chemical calculations. Compound 1 showed significant cytotoxicities against a panel of cancer cell lines (IC50s 〈 5 μM). Mechanistic study revealed that 1 could induce the generation of ROS, leading to cell cycle arrest and cell apoptosis in drug-resistant cancer cell line HCT-15/5-FU.

Description: High-resolution multibeam bathymetric and seismic data enables a detailed morphological investigation of a submarine canyon (West Penghu Canyon) on the northeastern South China Sea margin, where twenty-three (23) scours are observed along the canyon thalweg. These scours form narrow topographic depressions in plan view and show asymmetrical morphologies in cross-section. The identified scours can be further divided into two groups (Types A and B) based on their sizes and relative locations. They are separated by a slope break at a water depth of ~2850 m. Type A scours (S1-S18) occur upslope from the slope break, whereas Type B scours (S19-S23) lie downslope from this same break. The scours are interpreted as net-erosional cyclic steps associated with turbidity currents flowing through the West Penghu Canyon; the currents that form Type A scours reflect higher V, Q, and Δel compared to the currents forming Type B scours. A change in slope gradient and loss of lateral confinement are proposed to control the change from Type A to Type B scours. Furthermore, Coriolis force influences the flow direction of turbidity currents, leading to the preferential development and larger incision depths of scours towards the southwestern flank of the West Penghu Canyon. Our results contribute to a better understanding on the origin of scours in submarine canyons across the world.

Description: Background Glioblastoma multiforme (GBM) is the most frequent, lethal and aggressive tumour of the central nervous system in adults. The discovery of novel anti-GBM agents based on the isocitrate dehydrogenase (IDH) mutant phenotypes and classifications have attracted comprehensive attention. Purpose Diterpenoids are a class of naturally occurring 20-carbon isoprenoid compounds, and have previously been shown to possess high cytotoxicity for a variety of human tumours in many scientific reports. In the present study, 31 cassane diterpenoids of four types, namely, butanolide lactone cassane diterpenoids (I) (1-10), tricyclic cassane diterpenoids (II) (11-15), polyoxybutanolide lactone cassane diterpenoids (III) (16-23), and fused furan ring cassane diterpenoids (IV) (24-31), were tested for their anti-glioblastoma activity and mechanism underlying based on IDH1 mutant phenotypes of primary GBM cell cultures and human oligodendroglioma (HOG) cell lines. Results We confirmed that tricyclic-type (II) and compound 13 (Caesalpin A, CSA) showed the best anti-neoplastic potencies in IDH1 mutant glioma cells compared with the other types and compounds. Furthermore, the structure-relationship analysis indicated that the carbonyl group at C-12 and an α, β-unsaturated ketone unit fundamentally contributed to enhancing the anti-glioma activity. Studies investigating the mechanism demonstrated that CSA induced oxidative stress via causing glutathione reduction and NOS activation by negatively regulating glutaminase (GLS), which proved to be highly dependent on IDH mutant type glioblastoma. Finally, GLS overexpression reversed the CSA-induced anti-glioma effects in vitro and in vivo, which indicated that the reduction of GLS contributed to the CSA-induced proliferation inhibition and apoptosis in HOG-IDH1-mu cells. Conclusion Therefore, the present results demonstrated that compared with other diterpenoids, tricyclic-type diterpenoids could be a targeted drug candidate for the treatment of secondary IDH1 mutant type glioblastoma through negatively regulating GLS.