Exposure to silver impairs the osmoregulatory capability of euryhaline medaka (Oryzias latipes) subjected to salinity changes.

The widespread use of silver in nanomaterials has led to increases in environmental contamination, which poses a threat to aquatic animals. Euryhaline fish, which live in environments with fluctuating salinity levels, have strong osmotic regulatory abilities to cope with such changes. This study attempted to investigate how silver affects the osmoregulatory capabilities of euryhaline fish, using medaka (Oryzias latipes) embryos as a model. The embryos were exposed to AgNO3 for 7 d in either fresh water (FW) or seawater (SW), and their mortality, heart rate, morphology, and ionocytes were examined. Results showed that the toxicity of AgNO3 was higher in FW than in SW (50% lethal concentrations (LC50) were 0.17 vs. 1.01 ppm). Although AgNO3 (0.05 and 0.1 ppm) did not significantly change the morphology of embryos, it impaired ionocytes and elevated heart rates in FW. While, AgNO3 (0.1 and 0.5 ppm) did not affect the morphology, ionocytes, or heart rate in SW, it impaired the hypo-osmoregulatory capability and elevated the mortality of embryos that were transferred from FW to SW. At 12 h after SW transfer, ionocytes were severely impaired, and water-drinking behavior was suppressed, resulting in body dehydration and sodium overload. In contrast, AgNO3 did not elevate the mortality of embryos that were transferred from SW to FW. To sum up, the presence of silver in FW during the developmental stage of euryhaline fish could potentially endanger their survival during SW adaptation.

Auxin plays a role in the adaptation of rice to anaerobic germination and seedling establishment.

Auxin is well known to stimulate coleoptile elongation and rapid seedling growth in the air. However, its role in regulating rice germination and seedling establishment under submergence is largely unknown. Previous studies revealed that excessive levels of indole-3-acetic acid(IAA) frequently cause the inhibition of plant growth and development. In this study, the high-level accumulation of endogenous IAA is observed under dark submergence, stimulating rice coleoptile elongation but limiting the root and primary leaf growth during anaerobic germination (AG). We found that oxygen and light can reduce IAA levels, promote the seedling establishment and enhance rice AG tolerance. miRNA microarray profiling and RNA gel blot analysis results show that the expression of miR167 is negatively regulated by submergence; it subsequently modulates the accumulation of free IAA through the miR167-ARF-GH3 pathway. The OsGH3-8 encodes an IAA-amido synthetase that functions to prevent free IAA accumulation. Reduced miR167 levels or overexpressing OsGH3-8 increase auxin metabolism, reduce endogenous levels of free IAA and enhance rice AG tolerance. Our studies reveal that poor seed germination and seedling growth inhibition resulting from excessive IAA accumulation would cause intolerance to submergence in rice, suggesting that a certain threshold level of auxin is essential for rice AG tolerance.

Suppression of 12-O-tetradecanoylphorbol-13-acetate-induced MCF-7 breast adenocarcinoma cells invasion/migration by α-tomatine through activating PKCα/ERK/NF-κB-dependent MMP-2/MMP-9 expressions.

α-Tomatine, isolated from Lycopersicon esculentum Linn., is a naturally occurring glycoalkaloids in immature green tomatoes. Some reports demonstrated that α-tomatine had various anti-carcinogenic properties. First, the result demonstrated α-tomatine could inhibit TPA-induced the abilities of the adhesion, morphology/actin cytoskeleton arrangement, invasion, and migration by cell-matrix adhesion assay, immunofluorescence stain assay, Boyden chamber invasion assay, and wound-healing assay. Data also showed α-tomatine could inhibit the activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and protein kinase C-α (PKCα) involved in the downregulation of the enzyme activities and messenger RNA levels of matrix metalloproteinase-2/9 (MMP-2/MMP-9) induced by TPA. Next, α-tomatine also strongly inhibited TPA-induced the activation of nuclear factor kappa B (NF-κB) and phospho-inhibitor of kappa Bα (phospho-IκBα). In addition, TPA-induced translocation of PKC-α from cytosol to membranes, and suppression of TPA elicited the expression of PKC-α by adding the PKC-α inhibitors, GF-109203X and Gö-6983. The treatment of specific inhibitor for ERK (U0126) to MCF-7 cells could inhibit TPA-induced MMP-2/MMP-9 and phospho-ERK along with an inhibition on cell invasion and migration. Application of α-tomatine to prevent the invasion/migration of MCF-7 cells through blocking PKCα/ERK/NF-κB activation is first demonstrated herein.