Impact of light quality and quantity on growth rate kinetics of Selenastrum capricornutum

Microalgal biomass produced in indoor photobioreactors can be used as inoculum for large‐scale outdoor cultures or directly for the production of high‐value bioproducts due to the higher control of these cultures compared with outdoor systems. One of the main costs of indoor microalgal cultures is the illumination. This work can be used as a basis for the optimization of the light source for indoor microalgal biomass production, based on the light source type, irradiance, productivity, growth rate, attenuation coefficients, and contaminant growth on the reactor's side‐walls. Four commercially available near 400‐W artificial light sources for microalgal cultures (metal halide (MH), high‐pressure sodium (HPS), Son Agro^®, and fluorescent) were compared. The light elevation and the surface scalar irradiance were shown to have a linear relationship. The attenuation coefficient in air (k_a) was highest with Son Agro^®. A linear partition of the attenuation coefficient between the water and biomass and an exponential relationship between average scalar irradiance and depth were found. An empirical overall scalar attenuation coefficient for each light source was obtained. The lowest maximum observed growth rate was obtained with fluorescent light (0.98 d^?1) and the highest with Son Agro^® (2.39 d^?1). The highest growth on the reactor's wall was obtained with Son Agro^®. Further studies resulted in a higher maximum specific growth rate and optimum irradiance for HPS (2.37 d^?1 and 460 μmol s^?1 m^?2) compared with those observed with MH (1.73 d^?1 and 391 μmol s^?1 m^?2).     

The upper thermal tolerance for a Texas population of the hairy maggot blow fly Chrysomya rufifacies Macquart (Diptera: Calliphoridae)

1. The hairy maggot blow fly (Chrysomya rufifacies: Macquart) is an invasive necrophagous fly found throughout the continental United States. Chrysomya rufifacies is of medical/veterinary, forensic, and ecological importance due to its ability to cause myiasis, colonise human remains, and displace native Diptera. However, little is known about their upper thermal tolerance, which could be used to better predict their invasion potential.
2. We investigated the upper thermal tolerance of C. rufifacies exposed to different temperatures (20–45 °C), times (1–6 h), and nutrients (no food or water, water only, or a food-water mixture) for both sexes and two age ranges (young = 6–8 days post pupal emergence; old = 9–11 days post pupal emergence).
3. As temperature or duration increased, the probability of knockdown increased (0–100% at 20 and 45 °C and from 41 to 75% at 1 and 6 h), while the probability of survival decreased (99–2% at 20 and 45 °C and from 75 to 28% at 1 and 6 h). The availability of nutrients increased thermal tolerance at moderate temperatures (40 and 42 °C). Female flies were more thermally tolerant than males (probability of knockdown = 49% vs 58%; probability of survival = 58% vs 46%). Thermal tolerance did not differ by age.
4. These data reveal details about the upper thermal tolerance for a single population of C. rufifacies, and suggest that environmental and organismal factors ought to be considered in order to make meaningful predictions about the invasion potential of C. rufifacies in North America.

     

Diverse communities of active Bacteria and Archaea along oxygen gradients in coral reef sediments

Microbial communities inhabiting highly permeable sediments of Checker Reef in Kaneohe Bay, Hawaii, were characterized in relation to porewater geochemistry (O₂, NO₃ ⁻, NO₂ ⁻, NH₄ ⁺, phosphate). The physiologically active part of the population, assessed by sequencing cDNA libraries of 16S rRNA amplicons, was very diverse, with an estimated ribotype richness ≥1,380 in anoxic sediment. Quantitative analysis of community structure by rRNA-targeted fluorescence in situ hybridization (FISH) indicated that the archaeal population (9–18%) was dominated by marine Crenarchaeota (5–9%). Planctomycetales were the most abundant group in the oxic and interfacial habitat (17–19%) but were a minority (<5%) in anoxic reef sediment, where γ-Proteobacteria were numerically dominant (18%). Another 9–14% of the microbial benthos belonged to β-Proteobacteria, predominantly within the order Nitrosomonadales, many cultured representatives of which are NH₄ ⁺ oxidizers. The results of this study contribute to the phylogenetic characterization of benthic microbial communities that are important in organic matter degradation and nutrient recycling in coral reef ecosystems.     

The Cellular Distribution of Serotonin Transporter Is Impeded on Serotonin-Altered Vimentin Network

Background

The C-terminus of the serotonin transporter (SERT) contains binding domains for different proteins and is critical for its functional expression. In endogenous and heterologous expression systems, our proteomic and biochemical analysis demonstrated that an intermediate filament, vimentin, binds to the C-terminus of SERT. It has been reported that 5HT-stimulation of cells leads to disassembly and spatial reorientation of vimentin filaments.

Methodology/Principal Findings

We tested the impact of 5HT-stimulation on vimentin-SERT association and found that 5HT-stimulation accelerates the translocation of SERT from the plasma membrane via enhancing the level of association between phosphovimentin and SERT. Furthermore a progressive truncation of the C-terminus of SERT was performed to map the vimentin-SERT association domain. Deletion of up to 20, but not 14 amino acids arrested the transporters at intracellular locations. Although, truncation of the last 14 amino acids, did not alter 5HT uptake rates of transporter but abolished its association with vimentin.To understand the involvement of 5HT in phosphovimentin-SERT association from the plasma membrane, we further investigated the six amino acids between Δ14 and Δ20, i.e., the SITPET sequence of SERT. While the triple mutation on the possible kinase action sites, S₆₁₁, T₆₁₃, and T₆₁₆ arrested the transporter at intracellular locations, replacing the residues with aspartic acid one at a time altered neither the 5HT uptake rates nor the vimentin association of these mutants. However, replacing the three target sites with alanine, either simultaneously or one at a time, had no significant effect on 5HT uptake rates or the vimentin association with transporter.

Conclusions/Significance

Based on our findings, we propose that phosphate modification of the SITPET sequence differentially, one at a time exposes the vimentin binding domain on the C-terminus of SERT. Conversely, following 5HT stimulation, the association between vimentin-SERT is enhanced which changes the cellular distribution of SERT on an altered vimentin network.     

Conserving species‐rich predator assemblages strengthens natural pest control in a climate warming context

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