Bioavailability and trophic transfer of humic-bound copper from bacteria to zooplankton

ABSTRACT: The effect of humic acid (HA) on uptake and transfer of Cu by selected marine organisms from the microbial loop was determined. Bacteria grown with and without 15 µg Cu l-1 and with and without 10 mg Suwannee River Humic Acid (SRHA) l-1 were fed to Uronema sp. The Uronema were subsequently fed to Acartia tonsa to determine the effect of humic acid on the uptake and transfer of Cu from bacteria to copepods. The presence of 10 mg SRHA l-1 reduced Cu uptake in A. tonsa by an average of 54% and significantly reduced the negative effects of Cu on reproductive success ofA. tonsa. The percentage of the total Cu residues in A. tonsa resulting from feeding was estimated by exposing A. tonsa to the same conditions with and without pre-exposed Uronema as food. The results indicate that approximately 50% of the Cu residue is due to feeding. Thus, SRHA seems to affect Cu uptake in A. tonsa through binding of free Cu in the water at the same rate as through the food chain. This study demonstrates the importance of complexation of metals by organic matter and trophic transfer processes for organisms critical to estuarine food webs

Antioxidant activities of polyphenols extracted from Perilla frutescens varieties

Various cultivars of Perilla frutescens (L.) (var. crispa and var. frutescens) Britt. were harvested in China and Japan. They were easily differentiated on the basis of their foliage color, that varied from red to green. Water extracts of dried plants were investigated for their antioxidant activity (AA) and their polyphenolic compounds compared. Among them, cinnamic acid derivatives (coumaroyl tartaric acid, caffeic acid and rosmarinic acid), flavonoids (apigenin 7-O-caffeoylglucoside, scutellarein 7-Odiglucuronide, luteolin 7-O-diglucuronide, apigenin 7-O-diglucuronide, luteolin 7-Oglucuronide, and scutellarein 7-O-glucuronide) and anthocyanins (mainly cis-shisonin, shisonin, malonylshisonin and cyanidin 3-O-(E)-caffeoylglucoside-5-O-malonylglucoside) were quantified. AA assays are based on the inhibition of the free radical 2,2-diphenyl-1- picrylhydrazyl (DPPH). The DPPH radical scavenging activity was calculated as Trolox® [(±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid] equivalent antioxidant capacity (TEAC). The mean amount of total phenolics of the water extracts (4-29 ?mol/100 mL) and the TEAC value calculated (23-167 ?mol TE/100 mL) confirmed the high antioxidant activity of these leaf water extracts. These results were highly correlated within some o-dihydroxylated polyphenolic compounds and AA. (Résumé d'auteur

ラット食道発癌モデルにおけるサイクリンD1の過剰発現

博士(医学)大阪市立大

Key physicochemical characteristics governing organic micropollutant adsorption and transport in ion-exchange membranes during reverse electrodialysis

The co-generation of electricity and electrodialysis of seawater in a hybrid system is a promising approach to overcome water scarcity. Reverse electrodialysis harvests energy from the salinity gradient, where seawater is used as a high salinity stream while secondary treated wastewater can be used as a sustainable low salinity stream. Treated wastewater contains organic micropollutants, which can be transported to the seawater stream. The current research establishes a connection between adsorption and transport of organic micropollutants in ion exchange membranes, using a cross-flow stack in adsorption and zero-current experiments. To mimic the composition of treated wastewater, a mixture of nineteen organic micropollutants of varied physicochemical characteristics (e.g. size, charge, polarity, hydrogen donor/acceptor count, hydrophobicity) at environmentally relevant concentrations was used. Depending on the charge, micropollutants develop different types of mechanisms responsible for short-distance interactions with ion-exchange membranes, which has a direct influence in their transport behavior. This study provides a rational basis for the optimization/design of next-generation ion-exchange membranes, in which the permeability toward organic micropollutants should be also included. This investigation highly contributes to understanding the potential hazard posed by organic micropollutants in reverse electrodialysis in seawater desalination systems, where treated wastewater is used as a low salinity stream

Storchastic: A Framework for General Stochastic Automatic Differentiation

Modelers use automatic differentiation (AD) of computation graphs to implement complex Deep Learning models without defining gradient computations. Stochastic AD extends AD to stochastic computation graphs with sampling steps, which arise when modelers handle the intractable expectations common in Reinforcement Learning and Variational Inference. However, current methods for stochastic AD are limited: They are either only applicable to continuous random variables and differentiable functions, or can only use simple but high variance score-function estimators. To overcome these limitations, we introduce Storchastic, a new framework for AD of stochastic computation graphs. Storchastic allows the modeler to choose from a wide variety of gradient estimation methods at each sampling step, to optimally reduce the variance of the gradient estimates. Furthermore, Storchastic is provably unbiased for estimation of any-order gradients, and generalizes variance reduction techniques to higher-order gradient estimates. Finally, we implement Storchastic as a PyTorch library at https://github.com/HEmile/storchastic.Comment: 30 pages, 2 figures, 1 table, accepted in NeurIPS 202

Spatial and Temporal Variability in Zooplankton Community Dynamics in Three Urbanized Bayous of the Pensacola Bay System, Florida, USA

Spatial and temporal patterns in zooplankton community composition and abundance in coastal areas of the Gulf of Mexico are not well understood. Spatial and temporal differences in zooplankton community composition and abundance from 10 stations located in four sites are presented (Pensacola Bay and Bayou Texar, Bayou Chico, and Bayou Grande, three adjacent mesohaline-tidal bayous affected by urban and industrial development). Statistically significant differences (P \u3c 0.05) were found in log-biovolume among sites. The mean biovolume of zooplankton was highest in Pensacola Bay (0.38 ml m-3) followed by Bayou Grande (0.21 ml m-3), Bayou Chico (0.14 ml m-3), and Bayou Texar (0.06 ml m-3). Mean zooplankton abundances (organisms m-3) in Pensacola Bay (3,100 m-3) and Bayou Grande (3,000 m-3) were more than double the abundances in Bayou Texar (1,400 m-3) and Bayou Chico (1,100 m-3). The calanoid copepod Acartia tonsa Dana was the dominant species in the study area. The observed differences in the zooplankton community may be attributable to either one or a combination of factors such as water quality (toxicity), predation, and nutrient availability. Zooplankton abundance increased following two hurricanes that impacted the study area