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The implications of temperature on bioenergetics for barramundi ( Lates calcarifer) were defined in an improved factorial model that encompassed revised parameters accounting for effects over the temperature range of 16-39 °C and size range of 10-3000 g. A revised growth function describing weight gain by barramundi as a function of fish weight and temperature was derived from farm and laboratory data and included a term for a shift in optimal temperature with fish size: Gain (g fish−1 day−1) = ( K + xT + yT 2 + zT3) * (weight) ax+ b. Maintenance energy and protein demand functions were also derived on a similar form, and all three functions combined to form the basis of a factorial model for energy and protein demand. Using this model, optimal iterative feed specifications were defined for a range of fish sizes at temperatures of 25, 30 and 35 °C. A feed demand model was also developed based on the demand for digestible energy (DE) at each of these temperatures. The model shows that at high temperatures (35 °C), there is an increase in digestible protein (DP) to DE demand, and that with increasing size, there is a decrease in the DP to DE demand. [ABSTRACT FROM AUTHOR]

Plasmonic materials can be utilized as effective platforms to enhance luminescent signals of luminescent metal nanoclusters (LMNCs). Both surface enhanced fluorescence (SEF) and shell-isolated nanoparticle-enhanced fluorescence (SHINEF) strategies take advantage of the localized and increased external electric field created around the plasmonic metal surface when excited at or near their characteristic plasmonic resonance. In this context, we present an experimental and computational study of different plasmonic composites, (Ag) Ag@SiO 2 and (Au) Au@SiO 2 nanoparticles, which were used to enhance the luminescent signal of Au nanoclusters coated with glutathione (GSH) molecule (Au 25 GSH NCs). This specific LMNC has recently attracted particular interest due to its luminescent response and characteristic photostability. Our study presents a wide characterization of the optical and morphologic features of the synthetized particles: plasmonic metal nanostructures and Au 25 GSH NCs through different experimental techniques including UV-Visible, IR, luminescent spectroscopies, along with TEM and AFM microscopies. Additionally, we have carried out computational simulations based on time-dependent density functional theory (TD-DFT) and classical electrodynamics simulation based on Mie Theory to support our experimental findings. In this study, we report up to 3-fold luminescence enhancement of Au 25 GSH NCs which is mainly attributed to slow dynamic SEF., (© 2025 Wiley-VCH GmbH.)

Certain secondary carotenoids, such as astaxanthin and canthaxanthin, are of growing economic interest in the fields of human nutrition, food, health and cosmetics, as well as feed and aquaculture, particularly due to their numerous biological activities, such as their remarkable antioxidant properties. The present study was devoted to assessing, in a photobioreactor, the feasibility of cultivating newly isolated Dysmorphococcus strains from the biodiversity of Reunion Island for the production of these valuable xanthophylls. The results showed that all these strains were capable of producing and accumulating canthaxanthin and astaxanthin in response to environmental stresses. Among them, a strain which presented interesting morphological, genetic and biochemical properties as compared to the other Dysmorphococcus strains was further cultivated in a 3 L benchtop photobioreactor and was found to produce maximum carotenoid-rich biomass concentrations and productivities of about 4 g L -1 dw and 0.055 g L -1 d -1 dw, respectively. We also found that the biomass contained up to 1.2 mg g -1 dw of canthaxanthin and 0.7 mg g -1 dw of different forms of astaxanthin, mainly astaxanthin monoesters. The productivity of these carotenoids was found to be lower than those observed for other microalgal species previously reported, and we suggested that further optimizations with respect to the cultivation and the carotenogenesis induction processes are needed to improve productivities and to make this locally isolated Dysmorphococcus strain useful for future commercial production of natural canthaxanthin and astaxanthin.

Haematococcus lacustris is a freshwater green microalgae species able to produce and accumulate astaxanthin in response to environmental stresses such as high light and nutrient deprivation. Astaxanthin is a xanthophyll carotenoid of growing economic interest due to its numerous biological activities, notably its strong antioxidant properties, which can be valued in the fields of nutrition, health, feed and aquaculture. The present study aims at evaluating the capacity of two newly isolated Haematococcus strains from the biodiversity of Reunion Island, to be cultivated in a photobioreactor and to produce astaxanthin. The results showed that both strains were able to grow in various nutritive media and to produce and accumulate astaxanthin in response to stresses, mainly in the form of astaxanthin monoesters, which represented up to 2% of the dry biomass weight and which were mostly composed of linoleic and linolenic acids. In fed-batch cultures using 3 L benchtop photobioreactors, the concentrations of biomass enriched in astaxanthin reached up to 3 g L -1 (dry weight) with biomass productivities of 0.04 and 0.02 g L -1 d -1 based on the durations of the vegetative stage and of the entire culture, respectively. In these cultures, the astaxanthin productivities were found to reach on average around 0.25 mg L -1 d -1 . Although these results were relatively low compared to the literature, the possibility of improving growth conditions in order to improve biomass and astaxanthin yields, to guarantee economic viability for cultivation at a commercial scale, was further discussed.

The production of algae is a crucial component of many aquaculture systems and the role of bacteria in this process is an important although complex one. We report the development of a new blocking primer that allowed PCR amplification of bacterial DNA in the presence of algal chloroplast DNA., (Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.)

Early stage phyllosoma larvae of the spiny rock lobster Jasus edwardsii were examined for swimming speed, feeding, oxygen consumption and nitrogen excretion as instantaneous performance indicators when exposed to different irradiance levels. Swimming speed was measured in recently hatched Stage I larvae while all other parameters were measured in larvae from hatch to mid-Stage V. The swimming speed of recently hatched Stage I phyllosoma increased logarithmically between light intensities of 2.9 x 10(14) and 1.8 x 10(16) quanta s(-1) cm(-2) indicating that, within this range, swimming activity was only suppressed at the lowest irradiance level. Larvae examined under dark (no light) conditions showed lower feed intake, oxygen consumption and nitrogen excretion than larvae under low (7.7 x 10(12) q s(-1) cm(-2)) and high (3.9 x 10(14) q s(-1) cm(-2)) light intensities, and this was a consistent pattern observed throughout development from hatch to Stage V. There was no difference in feeding, oxygen consumption and nitrogen excretion between larvae exposed to low and high light intensities. However, from mid-Stage I to mid-Stage V, the metabolic feeding efficiency (feed intake:oxygen consumption ratio) was consistently higher in larvae exposed to low light intensity than in phyllosoma assessed in the dark and under high irradiance. A light intensity of about 7.7 x 10(12) quanta s(-1) cm(-2) and no higher than 3.9 x 10(14) quanta s(-1) cm(-2) is recommended to stimulate feeding and optimise metabolic feeding efficiency in early larval stages of J. edwardsii.

The physiological response to temperature, in terms of oxygen consumption, nitrogen excretion and feed intake was examined in Jasus edwardsii larvae at mid-stages I-III. From stage I to stage III, the mass-specific oxygen consumption increased in a sigmoid pattern over the temperature range of 10-22 degrees C. The Q(10) value declined significantly from 14-18 to 18-22 degrees C range, indicating a reduced temperature dependence of larval metabolism at higher temperatures. At all stages, feed intake increased with increasing temperature but reached a plateau at the higher temperatures for stages I and II larvae. In contrast, nitrogen excretion increased linearly over this temperature range for all larval stages. Therefore, higher temperatures ( approximately 22 degrees C) may cause an energetic imbalance and reduce growth potential in early stage larvae. While the convection requirement index (quotient of feed intake and oxygen consumption) indicated an equivalent metabolic feeding efficiency from 14 to 22 degrees C, a consistent decline of the O/N ratio above 16-18 degrees C from stage I to stage III suggested that exposure to elevated temperatures may result in an increase in the amount of protein being diverted from growth to catabolic processes. Based on these results, a temperature of 18 degrees C is recommended for the culture of early stage J. edwardsii larvae.