High Light Intensity Research Articles

Toward Enhanced Biomimetic Artificial Visual Systems Based on Organic Heterojunction Optoelectronic Synaptic Transistors

AbstractArtificial visual systems, inspired by the human eye, hold significant potential in artificial intelligence. Optoelectronic synapses, integrating image perception, processing, and memory in a single device, offer promising solutions. The human eye exhibits different recognition accuracies for objects under varying light conditions. Therefore, a more biomimetic visual system is needed to better fit actual application scenarios. Here, an organic heterojunction‐based optoelectronic synaptic transistor (OHOST) is proposed to enhance biomimetic artificial visual systems. By utilizing the excellent carrier capture ability of core‐multi‐shell quantum dots (QDs) and the high exciton dissociation efficiency of heterojunction interfaces, the device achieves a recognition capability under different light intensities closely resembling that of the human eye. Under optimal light intensity, the recognition accuracy for the modified national institute of standards and technology (MNIST) dataset can reach 91.52%. Nevertheless, under both low and high light intensities, the accuracy drops to a low level. This work pushes the development of artificial visual systems toward higher levels of biomimicry.

The Ratio of A400/A1800 Mapping Identifies Chromosomal Regions Containing Known Photoprotection Recovery-Related Genes in Rice

The rice, like other plants, undergoes photoprotection mode by increasing nonphotochemical quenching (NPQ) in high light intensity (> 1200 µmol m− 2s− 1 PPFD), which attenuates photosystem II yield (φPSII) drastically. The plant remains in photoprotection mode even after light intensity becomes not stressful for an extended period. While there are significant differences in the time it takes for photoprotection to recover among different genotypes, its use is limited in plant breeding because measuring the chlorophyll fluorescence parameters in progressive actinic light after dark adaptation takes more than forty-five minutes per genotype. The study finds that instantly measured A400/A1800 ratio by five minutes in flag leaves of 25 diverse genotypes strongly associated with the φPSII400 differences between theoretical and actual, qPd400 and NPQ400 with R2 values 0.74, 0.65 and 0.60, respectively. In two consecutive years, GWAS of A400/A1800 ratio identified the regions with genes reported earlier for plant photoprotection recovery. Additionally, QTL analysis in a RIL population also identified the regions carrying known genes related to photoprotection. Thus, the A400/A1800 ratio can quickly phenotype many plants for easier introgression of the traits in popular cultivars. The identified genotypes, genes, and QTLs can be used to improve yield potential and allele mining.

Transcriptomic Analysis Provides New Insights into the Tolerance Mechanisms of Green Macroalgae Ulva prolifera to High Temperature and Light Stress.

Our research focused on understanding the genetic mechanisms that contribute to the tolerance of Ulva prolifera (Chlorophyta), a marine macroalgae, to the combined stress of high temperature and high light intensity. At the mRNA level, the up-regulated DEGs showed enrichment in pathways related to ribosomes, proteasomes, and peroxisomes. The spliceosome pathway genes were found to be vital for U. prolifera's ability to adapt to various challenging situations in all the comparison groups. In response to elevated temperature and light intensity stress, there was a significant increase in genes and pathways related to ribosomes, proteasomes, and peroxisomes, whereas autophagy showed an increase in response to stress after 24 h, but not after 48 h. These findings provide novel insights into how U. prolifera adapts to elevated temperature and light stress.

Sufficient Light Intensity Is Required for the Drought Responses in Sweet Basil (Ocimum basilicum L.)

Various environmental factors not only affect plant growth and physiological responses individually but also interact with each other. To examine the impact of light intensity on the drought responses of sweet basil, plants were subjected to maintenance of two substrate volumetric water contents (VWC) using a sensor-based automated irrigation system under two distinct light intensities. The VWC threshold was set to either a dry (0.2 m3·m−3) or sufficiently wet condition (0.6 m3·m−3) under low (170 μmol·m−2·s−1) or high light intensities (500 μmol·m−2·s−1). The growth and physiological responses of sweet basil (Ocimum basilicum L.) were observed over 21 days in the four treatment groups, where the combination of two environmental factors was analyzed. Under high light intensity, sweet basil showed lower Fv/Fm and quantum yield of PSII, compared to that under low light intensity, regardless of drought treatment. Fourteen days after drought treatment under high light intensity, stomatal conductance and the photosynthetic rate significantly reduced. Whereas plants under low light intensity showed similar stomatal conductance and photosynthetic rates regardless of drought treatment. Assessment of shoot and root dry weights revealed that plant growth decline caused by drought was more pronounced under high light intensity than under low light intensity. Thus, sweet basil showed significant declines in growth and physiological responses owing to drought only under high light intensity; no significant changes were observed under low light intensity.

Effects of LED lights and cytokinin on the phytotreatment of simulated swine wastewater by Azolla spp.: Pollutant removal and biomass valorization

Phytoremediation is an eco-friendly and affordable option for tackling wastewater pollutants. The study focused on how light-emitting diodes (LED) light exposure, measured by intensity and duration (photoperiod), along with cytokinin, impacts Azolla microphylla's simulated swine wastewater treatment performance and biomass production. Under optimal treatment conditions, high removals of COD (89.2 % to 90.8 %), N-NH4+ (72.6 % to 91.2 %), N-NO3- (84.4 % to 88.6 %), Cu (75.4 % to 86.4 %), sulfamethoxazole (77.0 % to 79.0 %), P-PO43- (54.1 % to 59.9 %) and DOC (67.4 % to 71.3 %) while Zn presented a more moderate reduction (2.0 % to 9.7 %). Biomass productivity reached up to 34.8 t ha-1 yr-1. Protein production accounted for 23 % to 27 % of dry weight, while lipids ranged from 20 % to 34 % of dry biomass. Carbohydrate content varied from 8 % to 28 % of fresh weight. Higher light intensities, with both high or low values of photoperiods, and low concentrations of cytokinin were identified as optimal conditions for removal of almost all pollutants. However, pollutant removal was impacted differently by LED light and cytokinin concentration. In treatment conditions with the shortest photoperiods (8 h), the lowest residual Cu and Zn concentrations, whereas with longer photoperiods (24 h), the lowest residual concentrations of N-NH4+ and P-PO43- concentrations were recorded. On the other hand, SMX was the only parameter in which cytokinin had a clear influence on its removal, with the lowest residual concentration observed under 8-hour photoperiods combined with the lowest tested cytokinin concentrations (0.3 mg L-1). For residual COD and N-NO3-, no discernible pattern was evident for any of the analyzed factors. Therefore, the study demonstrates the potential for treating simulated swine wastewater using Azolla microphylla, aligned with its ability to produce biomass rich in high-value compounds.

Effect of Curing Light with Different Intensities on the Penetration of Silver and Fluoride Ions and Dentin Hardness in Primary Carious Molars Following Silver Diamine Fluoride Application: A Comparative Microscopic Ex Vivo Study.

A paradigm shift from surgical to medical approach for caries management has popularized silver diamine fluoride (SDF) as a preventive and interim caries arrest medicament. Few studies conducted have explored the effect of curing light on SDF's microbial property, its penetration, and effect on dentin. However, there is a research gap regarding the effect of different intensities of curing light on SDF performance. To determine the effect of different curing light intensities on SDF penetration depth and dentin hardness in carious lesions of primary molars. Silver diamine fluoride was applied on 30 extracted carious primary molars. Teeth were randomly allocated into three groups-(1) control group, no light curing after application of SDF; (2) light curing of SDF with low intensity (1000 mW/cm2); and (3) light curing of SDF with high intensity (2500 mW/cm2). A scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis was performed to check ion penetration after 1 week, and a Vickers hardness test was used to assess dentin hardness of both infected and affected dentin layers at 1-week and 1-month intervals. Based on the distribution of data, parametric and nonparametric tests were applied. Statistical Package for the Social Sciences (SPSS) version 26 was used for statistical analysis. The level of significance was set at 5%. Silver diamine fluoride penetrated beyond the carious lesion in all three groups. The mean silver ion precipitation in infected dentin in group III (16.90 ± 0.68) was maximum, whereas it was found to be minimum in group II (7.31 ± 0.63). The mean fluoride ion precipitation in affected dentin in group III (4.06 ± 0.41) was highest and least in group II (3.09 ± 0.58). A considerable increase in mean dentin hardness of infected dentin was observed in all three groups (214.00 ± 89.06, 218.00 ± 75.17, 231.00 ± 98.86, respectively; p < 0.001) after 1 month. Applying SDF to carious lesions using a high-intensity dental curing light induced more silver ion precipitation in infected dentin and increased its hardness. Bhatt R, Patel M, Thakkar A, et al. Effect of Curing Light with Different Intensities on the Penetration of Silver and Fluoride Ions and Dentin Hardness in Primary Carious Molars Following Silver Diamine Fluoride Application: A Comparative Microscopic Ex Vivo Study. Int J Clin Pediatr Dent 2024;17(7):766-772.

Maltese Coastline Never Sleeps: The Effects of Artificial Light at Night (ALAN) on the Local Infralittoral Assemblages—A Case Study

Aside from the most notorious threats, the Mediterranean Sea faces novel and poorly explored impacts from artificial light at night (ALAN), which influences natural light–dark cycles and affects marine ecosystems. This study investigates the impact of ALAN on coastal infralittoral assemblages in Malta, where such effects remain unexplored. Using Baited Remote Underwater Videos (BRUVs), we examined the influence of different light intensities on species assemblages and behaviour at two sites: a light-polluted harbour and a darker reef area. Our findings reveal significant differences in fish community composition between light treatments and habitats. Among the 23,955 individuals recorded across multiple taxa, Boops boops accounted for 80% of observations. From our results, light intensity had a more substantial impact on community structure than habitat type, with species-specific responses to light. Predatory species such as Trachurus trachurus displayed increased activity under high-intensity white light, while Apogon imberbis and Serranus scriba were more abundant under red light, irrespective of habitat. These results underscore the role of ALAN in altering marine community dynamics and emphasise the need for sustainable management strategies to mitigate its impact on the biodiversity of the Mediterranean. This study provides initial empirical evidence of ALAN’s effects in Maltese waters, contributing to broader efforts to understand and manage light pollution in marine ecosystems.

Reduced diffusional limitations in carnation stems facilitate higher photosynthetic rates and reduced photorespiratory losses compared with leaves.

Green stem photosynthesis has been shown to be relatively inefficient but can occasionally contribute significantly to the carbon budget of desert plants. Although the possession of green photosynthetic stems is a common trait, little is known about their photosynthetic characteristics in non-desert species. Dianthus caryophyllus is a semi-woody species with prominent green stems, which show similar photosynthetic anatomy with leaves. In the present study, we used a combination of gas exchange and chlorophyll fluorescence measurements, some of which were taken under varying O2 and CO2 partial pressures, to investigate whether the apparent anatomical similarities between the species' leaves and stems translate into similar photosynthetic physiology and capacity for CO2 assimilation. Both organs displayed high photosynthetic electron transport rates (ETR) and similar values of steady-state non-photochemical quenching (NPQ), albeit leaves could attain them faster. The analysis of OJIP transients showed that the quantum efficiencies and energy fluxes along the photosynthetic electron transport chain are largely similar between leaves and stems. Stems displayed higher total conductance to CO2 diffusion, similar biochemical properties, significantly higher photosynthetic rates and lower water use efficiency than leaves. Leaf ETR was more sensitive to sub-ambient O2 and super-ambient CO2 partial pressures, while leaves also displayed a higher relative rate of Rubisco oxygenation. We conclude that the highly responsive NPQ and the enhanced photorespiration and WUE in leaves represent photoprotective and water-conserving adaptations to the high incident light intensities they experience naturally, at the expense of higher CO2 assimilation rates, which the vertically orientated stems can readily attain.

Passive Cooling of Natural Ventilated Polyhouse During Summer using IR Reflective Film

The high temperature (soil and air) and light intensity are major challenge in utilizing the natural ventilated polyhouse (PH) during summer season. There is urgent need to develop passive cooling system to address the challenge so that natural ventilated PH can be utilized for round the year cultivation. The IR reflective film have novel property in addressing the challenge, so it is utilized to develop natural ventilated PH to passively cool it during summer season. The efficacy of IR reflective film in cooling the natural ventilated PH is compared with open field and clear film by measuring the microclimate parameters and crop growth parameters. The increase in maximum temperature under clear film PH and IR reflective film PH are 6.2°C and 1.5°C respectively in comparison to open field. The IR reflective film is more suitable than clear film in reducing the temperature during summer season. The increase in yield under IR reflective film PH is 7.6% more than clear film PH due to suitable microclimate conditions under IR reflective film PH.

Ultrasensitive detection of remote acoustic vibrations at 300 m distance by optical feedback enhancement

Sensitive detection of remote vibrations at nanometer scale owns promising potential applications such as geological exploration, architecture, and public security. Nevertheless, how to detect remote vibration information with high sensitivity and anti-disturbance has become a major challenge. Reported current non-contact measurement methods are difficult to simultaneously possess characteristics of high light intensity sensitivity, long working distance, high vibration response sensitivity, and anti-disturbance of ambient light. Here, we propose a polarization-modulated laser frequency-shifted feedback interferometry method with the above characteristics, to obtain remote vibration information. The method can directly measure non-cooperative targets without the need for any cooperative markers. In each interference cycle, the energy as low as 2.3 photons can be effectively responded to, and the vibration amplitude sensitivity at 300 m can reach 0.72 nm/Hz1/2 at 1 kHz. This approach provides a strategy for the ultrasensitive detection of remote vibration that is immune to electromagnetic interference.

Genome-Wide Identification of the Class III Peroxidase Gene Family in Ginger and Expression Analysis under High Temperature and Intense Light Stress

Ginger, valued for its medicinal properties and economic significance, is vulnerable to environmental stressors such as intense light and high temperatures, which can hinder its growth and development. Class III peroxidases (PRXs) are plant-specific oxidoreductases essential for plant development, growth, and stress responses. Despite their importance, there is limited information available on the function of the class III peroxidase gene family in ginger (ZoPRX). In this study, 103 ZoPRX members within the ginger genome were identified, unevenly distributed across 11 chromosomes. The identified ZoPRX members were categorized into five subfamilies based on gene structures, protein motifs, and phylogenetic analysis. Gene duplication analysis revealed that ZoPRX has primarily undergone segmental duplication. Interspecies homology analysis between ginger and Arabidopsis thaliana, Oryza sativa, and Musa acuminata suggested most ZoPRXs in ginger originated after the divergence of dicotyledon and monocotyledon. Analysis of promoter cis-acting elements identified defense and stress response elements in 39 genes and hormone response elements in 95 genes, indicating their potential roles in responding to environmental stresses. Quantitative Real-Time PCR (qRT-PCR) analysis confirmed that the majority of ZoPRX members are responsive to high temperature and intense light stress. This study provides a comprehensive understanding of the PRX family in ginger, thereby laying the groundwork for future investigations into the functional role of ZoPRX genes under high-temperature and intense light-stress conditions.

Contrasting Dynamic Photoprotective Mechanisms under Fluctuating Light Environments between an Andean and a Mesoamerican Genotype of Phaseolus vulgaris L.

Plants have evolved various photosynthetic adaptations and photoprotective mechanisms to survive in fluctuating and extreme light environments. Many light-activated photosynthetic proteins and enzymes adjust to plant leaf anatomy and leaf pigments to facilitate these processes. Under excessive amounts of light, plants use non-photochemical quenching (NPQ) mechanisms to dissipate excess absorbed light energy as heat to prevent photoinhibition and, therefore, mitigate damage to the plant’s photosystems. In this study, we examined photosynthetic adaptations to the light environment in common beans using representative genotypes of the Andean (Calima) and the Mesoamerican (Jamapa) gene pools. We estimated their leaf chlorophyll fluorescence characteristics using dark- and light-adapted mature leaves from three-week-old plants. Our results indicated a higher chlorophyll fluorescence of the light-adapted leaves in the Mesoamerican genotype. NPQ induction was early and extended in the Andean genotype. A similar response in the Mesoamerican counterpart required high light intensity (≥1500 PAR). The NPQ relaxation was rapid in the Mesoamerican genotype (t1/2: 6.76 min) but sluggish in the Andean genotype (t1/2: 9.17 min). These results indicated variable adaptation to light environments between the two common bean genotypes and suggested different strategies for surviving fluctuating light environments that can be exploited for developing plants with environmentally efficient photosynthesis under light limitations.

Increase in polyunsaturated fatty acids and carotenoid accumulation in the microalga Golenkinia brevispicula (Chlorophyceae) by manipulating spectral irradiance and salinity.

Microalgal biotechnology offers a promising platform for the sustainable production of diverse renewable bioactive compounds. The key distinction from other microbial bioprocesses lies in the critical role that light plays in cultures, as it serves as a source of environmental information to control metabolic processes. Therefore, we can use these criteria to design a bioprocess that aims to stimulate the accumulation of target molecules by controlling light exposure. We study the effect on biochemical and photobiological responses of Golenkinia brevispicula FAUBA-3 to the exposition of different spectral irradiances (specifically, high-fluence PAR of narrow yellow spectrum complemented with low intensity of monochromatic radiations of red, blue, and UV-A) under prestress and salinity stress conditions. High light (HL) intensity coupled to salinity stress affected the photosynthetic activity and photoprotection mechanisms as shown by maximal quantum yield (Fv/Fm) and non-photochemical quenching (NPQmax) reduction, respectively. HL treatments combined with the proper dose of UV-A radiation under salinity stress induced the highest carotenoid content (2.75 mg g dry weight [DW]- 1) composed mainly of lutein and β-carotene, and the highest lipid accumulation (35.3% DW) with the highest polyunsaturated fatty acid content (alpha-linolenic acid (C18:3) and linoleic acid (C18:2)). Our study can guide the strategies for commercial indoor production of G. brevispicula for high-value metabolites.

Impact of dye treatment as management strategy on available light may favour a highly invasive alien aquatic plant

Attempts to control massive proliferations of invasive alien aquatic plants (IAAP) are often ineffective. A renewed interest for dye treatment is emerging aiming to control the submerged macrophyte Myriophyllum heterophyllum in France. We aimed to understand the effects of dye on this plant knowing about its adaptation to low light. In a 2 × 2 factorial design experiment, we assessed the effect of a dye mixture based on Brilliant Blue (E133) and Allura Red (E129) at high and low light intensities on light quantity and quality and how this might affect the plant’s performance by measuring morphological and physiological traits. A multivariate analysis identified three groups – high light (HL) plants, plants in high light with dye (HLD) or low light (LL), and low light with dye (LLD) plants. HL plants performed well but showed stress signs, with a reduced main shoot length, a higher leaf dry matter content (LDMC) and a lower nitrogen content (N), not observed in plants grown in HLD or LL. HLD and LL plants exhibited a comparable total length growth rate to those in HL, but had lower LDMC and higher N contents. LLD plants performed poorly with the lowest growth and signs of physiological stress. Dye-induced changes in light quality only marginally affected the absorbance range of chlorophyll b, which apparently did not affect photosynthesis. Commercially available dyes currently used to control nuisance aquatic plants thus seem to have little or no effect on submerged macrophytes. The presence of dye may exacerbate negative effects of very low light intensities on the plant’s growth. However, these very low intensities would only be reached during high-water levels or in winter, periods where the dye would rapidly be diluted. During summer, however, the application of dye may protect the plant from damaging light intensities and thus not be a good management strategy to control low light adapted invasive submerged macrophytes.

Sapphire-Based Optrode for Low Noise Neural Recording and Optogenetic Manipulation.

Electrophysiological recordings of neurons in deep brain regions using optogenetic stimulation are essential to understanding and regulating the role of complex neural activity in biological behavior and cognitive function. Optogenetic techniques have significantly advanced neuroscience research by enabling the optical manipulation of neural activities. Because of the significance of the technique, constant advancements in implantable optrodes that integrate optical stimulation with low-noise, large-scale electrophysiological recording are in demand to improve the spatiotemporal resolution for various experimental designs and future clinical applications. However, robust and easy-to-use neural optrodes that integrate neural recording arrays with high-intensity light emitting diodes (LEDs) are still lacking. Here, we propose a neural optrode based on Gallium Nitride (GaN) on sapphire technology, which integrates a high-intensity blue LED with a 5x2 recording array monolithically for simultaneous neural recording and optogenetic manipulation. To reduce the noise interference between the recording electrodes and the LED, which is in close physical proximity, three metal grounding interlayers were incorporated within the optrode, and their ability to reduce LED-induced artifacts during neural recording was confirmed through both electromagnetic simulations and experimental demonstrations. The capability of the sapphire optrode to record action potentials has been demonstrated by recording the firing of mitral/tuft cells in the olfactory bulbs of mice in vivo. Additionally, the elevation of action potential firing due to optogenetic stimulation observed using the sapphire probe in medial superior olive (MSO) neurons of the gerbil auditory brainstem confirms the capability of this sapphire optrode to precisely access neural activities in deep brain regions under complex experimental designs.

Mild osmotic stress offers photoprotection in Chlamydomonas reinhardtii under high light

The exposure of autotrophs to high light intensities significantly impacts their photosynthetic performance. When combined with unpredictable climate changes, the lethality of these effects is exacerbated and, often surpassing the organisms' threshold for tolerance. In this regard, our study centres on examining the mitigating effects of mild osmotic stress induced by 2% Polyethylene Glycol (PEG) in conjunction with high-light conditions, using Chlamydomonas reinhardtii as a model system. Cells were cultivated under low PEG-induced osmotic stress at various light intensities, and their responses were analyzed through biochemical and biophysical approaches. Remarkably, cells grown under lower PEG concentrations exhibited superior growth, increased biomass, and enhanced photosynthetic efficiency under high light compared to non-PEG-treated cells. Surprisingly, their non-photochemical quenching (NPQ) levels were lower, indicating the operation of a distinct photoprotective mechanism in PEG-grown samples. The PEG-grown cells demonstrated higher chlorophyll content but lower carotenoid content, supporting the NPQ data. Circular dichroism analysis suggested that the macro-organization of super-complexes was minimally disrupted in PEG-grown samples, even under high light. This was further supported by Blue native PAGE, which showed greater stability of the super-complexes in PEG-grown cells, implying heightened stability in pigment-protein interactions. Immunoblot analysis revealed minimal differences in core reaction center proteins between PEG-grown and non-PEG cells. Notably, this protective mechanism was absent in the cell wall-deficient mutant CC503. We propose that the partial photoprotection observed is attributed to the PEG shielding the cell wall. This result holds promise for enhancing algal biomass production under natural environmental conditions influenced by fluctuating light intensity.

The Thickness Changes of Anatomical Ornamental Monocotyledon Plant Leaves Affected by the Interactions between Plant Types and Light Intensity

The different levels of light intensity affect the anatomical thickness of monocotyledon ornamental plant leaves. The aim of this research was to determine the anatomical thickness of several monocotyledon ornamental plant leaves under different light intensities. The research used a factorial complete randomized design with two main factors, namely plant type and different light intensity, repeated three times. The first factor was the plant type, which consisted of six plant species of monocotyledon ornamental plants which were Chlorophytum laxum, Dracaena reflexa, Rhoeo discolor, Aglaonema commutatum, Cordyline fruticosa and Hymenocallis littoralis. The second factor was light intensity, which consisted of high light intensity (open areas) and low light intensity (shaded areas). The observation was carried out on preserved leaf anatomy made using the paraffin method with modification. The observation variables were the total thickness of the leaf, upper and lower epidermis, mesophyll (for undifferentiated mesophyll), and palisade and sponge (for differentiated mesophyll). Data were analyzed using analysis of variance followed by the LSD test if the treatment was significant. Correlation tests were carried out between total leaf thickness and each leaf anatomical part under conditions of high and low light intensity. The results showed that the interaction between plant types and light intensity influenced the total thickness of the leaves, upper and lower epidermis, and palisade. The plant types independently influenced the mesophyll and sponges, while the light intensity independently influenced only the mesophyll but not the sponge thickness. Hymenocallis littoralis was the only plant that showed thicker under low light intensity, with an increase in the thickness of the upper and lower epidermis. The palisade mainly influenced leaf thickness changes in the differentiated mesophyll.

Exploring effects of light intensity on sustainability indicators in finishing pig production

With an ongoing transition towards the use of Light Emitting Diodes, more knowledge is needed on which light settings optimise sustainability parameters in pig production. We studied the effects of four light intensities on social, environmental and economic sustainability indicators, including ammonia emissions, space use, pen fouling, weight gain, carcass quality, perception of the stockkeeper, costs of the light system, and use of drinking water, electricity and medicines. Light treatments included a low (45 lux), medium (198 lux) and high (968 lux) uniform intensity, and a spatial gradient treatment ranging from 71 lux in the front to 330 lux in the back of each pen. The latter treatment aimed to improve the space use of functional areas. A total of 448 growing-finishing pigs were studied on a commercial farm using two consecutive batches of four rooms containing eight pens with seven pigs. Light intensity influenced some aspects of space use and pen fouling. For example, the proportion of pigs lying in the resting area was higher in the high and medium light intensity treatment than in the low intensity and gradient treatment. Moreover, the high-intensity treatment resulted in more fouling with faeces in the feeding area compared with the low-intensity and the gradient treatment. Ammonia emissions were higher in the gradient than in the low intensity treatment (not measured in medium and high intensity treatment). Furthermore, light intensity did not affect weight gain, carcass quality, water use and medicine use. The stockkeeper was content to work in all light conditions, but slightly preferred the medium intensity due to optimal visibility. Concerning economic performance, the costs of the light system and electricity use increased in the following order: low intensity, gradient, medium intensity, and high intensity. In conclusion, contrary to expectation the spatial gradient did not notably improve space use or reduce pen fouling, but rather increased ammonia emissions in comparison with uniform light. This is likely because the gradient could not be applied in an optimal way in the existing housing conditions. Among the other sustainability indicators, mainly electricity use and costs of the light system differed per treatment. These aspects can be improved by further optimising the number of light sources needed per pen to achieve the targeted intensities.

Acclimation Strategies for the Black Sea Diatom Algae Ditylum brightwellii to High Intensity of Light

In cells of a culture of the large diatom Ditylum brightwellii (T. West) Grunow acclimated to faint light (17 μmol photons/(m2 s)), numerous chloroplasts are evenly distributed throughout the cell cytoplasm. After 10 min of exposure of algae to extremely high illumination (1100 μmol photons/(m2 s)), their aggregates gradually form in the center of the cell, and their formation continues until the end of the 2-h exposure period. At light intensities of 510–935 µmol photons/(m2 s) during short-term photoacclimation, the aggregation of chloroplasts is recorded for 20–60 min, after which their reverse movement and uniform distribution in the cytoplasm are revealed by the end of the second hour. Under conditions of a longer culture stay at a light intensity of 1100 μmol photons/(m2 s), the algae retains viability for only 6 h. Long-term photoacclimation of this species, which stops by the end of the second day, is detected when the light becomes half as weak. This is manifested in an increase in cell volume and in the C/Chl a ratio, in the increased aggregation of chloroplasts in the center of the cell, and in a decrease in a number of fluorescent parameters of the efficiency of photosystem II and of culture viability.

Microalgae in the Mediterranean area: A geographical survey outlining the diversity and technological potential

Microalgal diversity enables the possibility to employ them in technological applications, as widely shown by the modern literature. While there exists an extensive body of literature concerning the technological applications of microalgae, the scientific knowledge of microalgal species remains relatively limited. Therefore, there is still potential for unlocking new opportunities through the study of the microalgal biodiversity, particularly in the Mediterranean region, which is unique because of its sub regional diversity. While some studies have assessed microalgae distribution in the Mediterranean area, and others have focused on specific aspects of their technical exploitation, this review seeks to offer a comprehensive overview of isolated microalgal species and their technological applications. Microalgae from the Mediterranean area share common characteristics, such as low half-saturation constants and acclimation to high light intensity, making them ideal for specific technological applications. While the search for new microalgae for technological purposes can help in biodiversity conservation, numerous species still remain underexplored, offering potential for innovative applications. However, the key finding from the critical analysis of the literature is that the diversity of microalgae in the Mediterranean region is its true richness, allowing for their versatile applications across various processes. The work focuses on the Mediterranean area, i.e., having coastlines along the Mediterranean Sea and on aquatic microalgae, coming from water with different salinity levels. This review offers an intrinsic ecological and technological perspective and provides a fresh outlook on the microalgal sector, promoting its expansion in the Mediterranean area and the development of sustainable bio-industries.