Description: Climate change is affecting the health and physiology of marine organisms and altering species interactions. Ocean acidification (OA) threatens calcifying organisms such as the Pacific oyster, Crassostrea gigas. In contrast, seagrasses, such as the eelgrass Zostera marina, can benefit from the increase in available carbon for photosynthesis found at a lower seawater pH. Seagrasses can remove dissolved inorganic carbon from OA environments, creating local daytime pH refugia. Pacific oysters may improve the health of eelgrass by filtering out pathogens such as Labyrinthula zosterae (LZ), which causes eelgrass wasting disease (EWD). We examined how co-culture of eelgrass ramets and juvenile oysters affected the health and growth of eelgrass and the mass of oysters under different pCO(2) exposures. In Phase I, each species was cultured alone or in co-culture at 12 degrees C across ambient, medium, and high pCO(2) conditions, (656, 1,158 and 1,606 mu atm pCO(2), respectively). Under high pCO(2), eelgrass grew faster and had less severe EWD (contracted in the field prior to the experiment). Co-culture with oysters also reduced the severity of EWD. While the presence of eelgrass decreased daytime pCO(2), this reduction was not substantial enough to ameliorate the negative impact of high pCO(2) on oyster mass. In Phase II, eelgrass alone or oysters and eelgrass in co-culture were held at 15 degrees C under ambient and high pCO(2) conditions, (488 and 2,013atm pCO(2), respectively). Half of the replicates were challenged with cultured LZ. Concentrations of defensive compounds in eelgrass (total phenolics and tannins), were altered by LZ exposure and pCO(2) treatments. Greater pathogen loads and increased EWD severity were detected in LZ exposed eelgrass ramets; EWD severity was reduced at high relative to low pCO(2). Oyster presence did not influence pathogen load or EWD severity; high LZ concentrations in experimental treatments may have masked the effect of this treatment. Collectively, these results indicate that, when exposed to natural concentrations of LZ under high pCO(2) conditions, eelgrass can benefit from co-culture with oysters. Further experimentation is necessary to quantify how oysters may benefit from co-culture with eelgrass, examine these interactions in the field and quantify context-dependency.

Description: INTRODUCTION Prostate cancer (CaP) is the second leading malignancy in older men in Western countries. The role of CD44 variant 6 (CD44v6) in CaP progression and therapeutic resistance is still uncertain. Here, we investigated the roles of CD44v6 in CaP metastasis and chemo/radioresistance. Expression of CD44v6 in metastatic CaP cell lines, human primary CaP tissues and lymph node metastases was assessed using immunofluorescence and immunohistochemistry, respectively. METHODS Knock down (KD) of CD44v6 was performed in PC-3M, DU145, and LNCaP cells using small interfering RNA (siRNA), and confirmed by confocal microscope, Western blot and quantitative real time polymerase chain reaction (qRT-PCR). Cell growth was evaluated by proliferation and colony formation assays. The adhesive ability and invasive potential were assessed using a hyaluronic acid (HA) adhesion and a matrigel chamber assay, respectively. Tumorigenesis potential and chemo-/radiosensitivity were measured by a sphere formation assay and a colony assay, respectively. RESULTS Over-expression of CD44v6 was found in primary CaP tissues and lymph node metastases including cancer cells and surrounding stromal cells. KD of CD44v6 suppressed CaP proliferative, invasive and adhesive abilities, reduced sphere formation, enhanced chemo-/radiosensitivity, and down-regulated epithelial–mesenchymal transition (EMT), PI3K/Akt/mTOR, and Wnt/β-catenin signaling pathway proteins in vitro. CONCLUSIONS Our findings demonstrate that CD44v6 is an important cancer stem cell-like marker associated with CaP proliferation, invasion, adhesion, metastasis, chemo-/radioresistance, and the induction of EMT as well as the activation PI3K/Akt/mTOR and Wnt signaling pathways, suggesting that CD44v6 is a novel therapeutic target to sensitize CaP cells to chemo/radiotherapy. Prostate © 2014 Wiley Periodicals, Inc.