Java sparrows can modulate vocalizations in response to different light wavelengths.

Effects of postharvest light spectra on quality and health-related parameters in green Asparagus officinalis L.

The natural nighttime light environment of the earth has been significantly transformed by human activities. Such “light pollution” has a profound influence on ecosystems. Protected areas (PAs) play key ecological functions and are only effective at low light pollution levels or without any light pollution. In China, with rapid population growth and high urbanization rates, light pollution in PAs continues to aggravate and threaten a number of ecosystems. We used calibrated nighttime light images to study spatial-temporal changes in light pollution in China’s PAs from 1992 to 2012 by classifying light pollution into three levels (moderate, medium, and strong). The results showed that in China’s PAs, the area subject to light pollution increased by about 1.79 times, with a significant increase in the intensity of artificial light. The changes in light pollution exhibited significant regional differences. In the eastern developed regions, light pollution was more significant than that in other regions and the situation in East China was the most severe. In the Qinghai-Tibet, although light pollution was less significant, the area subject to light pollution increased significantly over the evaluated period. Factors influencing light pollution were also analyzed. Light pollution in a PA is influenced by both human activities and its own characteristics.

Ecological light pollution is increasing worldwide, but its threats to freshwater taxa and ecosystems are not well understood. Further, light-emitting diodes (LEDs) are currently replacing incandescent, fluorescent, and high-intensity discharge lights across much of the developed world. Cool-spectrum LED lights are characterized by shorter wavelength, cool-hued light, whereas warm-spectrum LED lights are characterized by longer wavelength, warm-hued light. It is unclear how spectral emissions produced by LED lights will affect freshwater animals, especially species with strong effects on stream ecosystems like crayfish. The New River crayfish (Cambarus chasmodactylus) and the spiny stream crayfish (Orconectes cristavarius) are important ecosystem engineers that can influence freshwater community structure. Here, we exposed these crayfish to cool (5000 K) and warm (3000 K) spectrum LED lights at ecologically-relevant intensities of 15 lx in a laboratory experiment. We recorded crayfish behaviors under each light treatment and in a dark control during the 1st and 3rd h after artificial dusk. We hypothesized that crayfish would reduce their activity and increase sheltering behavior under both light treatments. We found that O. cristavarius sheltering behavior significantly increased while exposed to both cool and warm spectrum LEDs at 2000 h. The statistical differences in these results disappeared at 2200 h. Cambarus chasmodactylus increased sheltering behavior in response to cool spectrum LEDs but not to warm spectrum LEDs at 2000 h. However, this pattern was reversed at 2200 h. The overall trend was that crayfish reduced their activity under artificial lights at night, although the responses of the 2 species varied somewhat. If crayfish activity is reduced by artificial lights at night, the effects of crayfish on aquatic systems may be altered in areas with extensive light pollution.

Given the central role of light in the algal photosynthesis, respiration, cell division, growth and the accumulation of value products, the effects of light-emitting diodes (LEDs) light wavelengths (blue, white, red and green) were studied in Scenedesmus obliquus. Biomass, residual nutrient amount, soluble protein, astaxanthin and reactive oxygen species, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity were analyzed to determine the effects of different monochromatic light wavelengths via biochemical methods. The results showed that blue light wavelength is the optimal light wavelength for phosphorus removal efficiency and the accumulation of biomass and astaxanthin in S. obliquus. Meanwhile, high reactive oxygen species content under the blue light might induce the accumulation of astaxanthin. The high activity of SOD, CAT and POD might participate in clearing the reactive oxygen species to facilitate the growth of microalgae. Furthermore, we found mixed blue/green lights treatment is the most appropriate mixture for the nitrogen removal. Under the blue light treatment, high light intensity and 18L:6D light cycle is the best condition for biomass and astaxanthin accumulation. Optimal nitrogen/phosphorus removal efficiency was observed under a 24L:0D light cycle. These results might provide a foundational data for the optimizing the productivity of high-value metabolites and treatment of wastewater.

This paper presents a novel approach for bird species identification that relies on both visual features extracted from unconstrained bird images and acoustic features extracted from bird vocalizations. The Scale Invariant Feature Transform (SIFT) detects local features in bird images, which are then used to train a support vector machine classifier. The instances that are not classified with a certain degree of certainty are then rejected and reclassified using Mel-frequency cepstral coefficients (MFCCs) extracted from the bird songs if available. Experiments conducted on a dataset of 50 bird species that comprise images from the CUB200-2011 and audio samples from Xeno-Canto have shown that improvements between 1.2 and 15.7 percentage points are achieved when using an acoustic classifier to re-process the instances rejected by the visual classifier, depending on the rejection level.

built environment the mixed blessing of Phosphor-based White leDs

The relationships between two brain stem regions where electrical stimulation (ESB) evokes repetitive vocalizations in birds were investigated in anesthetized chickens. Electrodes were placed in the midbrain call region (MCR) and in a region ventral to <i>nucleus ovoidalis </i>(OM) and checked for ESB-evoked calling. Then radio-frequency lesions were made in MCR and the OM site retested for evoked vocalizations. Lesions in MCR abolished calls evoked from OM indicating that OM excitation produces calls via ipsilateral MCR.

Light wavelength is a critical abiotic factor in modulating the development and pigment accumulation of microalgae. In the present study, we investigated the influences of white, red, blue, yellow, and green light on biomass (cell density), growth (cell diameter and dry weight), net photosynthetic rate, and pigment contents (chlorophyll a, fucoxanthin, and lutein) of the coccolithophore Emiliania huxleyi. The effects of light wavelength change on its cell density and fucoxanthin content were also evaluated. The results showed that blue light significantly stimulated the cell proliferation and photosynthetic activity of E. huxleyi. The cell diameter, dry weight, net photosynthetic rate, and the content of fucoxanthin under red light were significantly greater than under white light. E. huxleyi could not effectively utilize green light and yellow light for growth, photosynthesis, and pigment synthesis. Compared with white, blue, and red light, significantly greater cell density and fucoxanthin content were found under blue light, followed by red light. These findings indicated that light wavelength could significantly affect the growth, photosynthesis, and pigments of E. huxleyi. The combination of blue and red light is likely to be an effective measure to enhance its biomass and fucoxanthin production.

Amorphous InGaZnO (a-IGZO) has excellent properties such as high on/off ratio, good uniformity, and low processing temperature, so they are promising channel material for thin film transistors (TFTs). Instability mechanism of a-IGZO TFTs depending on environmental effects, bias, temperature and illumination stress was widely investigated and reported. Especially in the case of negative bias stress, degradation is accelerated under illumination and many studies have been done to clarify the causes. However, the effects of wavelength and intensity of light during negative bias stress under illumination stress (NBIS) have not been fully explained yet. Transfer characteristics of a-IGZO TFTs with back channel etch structure were measured after NBIS is applied. Gate voltage of -40 V was applied at 90 °C for 4000 s while drain and source were grounded. Illumination from white LED was passed through blue, green and red color filters which have peak wavelengths of 450 nm, 530 nm and 700 nm, respectively. To verify the relationship between intensity of light and degradation, measurements were done with various intensities of light. Severe negative shifts in transfer curve was shown under NBIS with blue light, while relatively little shifts were shown with green, red light and in darkness (Fig. 1). Apparent degradation in subthreshold slope was observed with blue light, which represents the creation of sub-gap states (Fig. 1d). Shifts in Vth as a function of stress time were extracted with various illumination conditions (Fig.2). The intensities of illumination were 4500 lux for white and 100 lux for blue, green and red light. Despite of much lower intensity compared to that of white light, blue light induced comparable amount of Vth shifts with that of white light; Vthshifts after 4000 s of stress were about -17.7 V for white and -16.3 V for blue light, but were only about -1.0 V for green light, -0.8 V for red light and -0.7 V for in darkness. To clarify the effect of intensity in blue light, we adjusted the intensity as 100, 50, 25, 12 and 6 lux with the same stress condition. Amount of Vth shifts were not significantly altered until the illumination was reduced to 25 lux, but started to show drastic decrease below 25 lux (Fig. 3a). It indicates that threshold intensity of illumination and saturation phenomenon exist in NBIS induced degradation of IGZO TFTs. Measurements were repeated at 60 °C and Vthshifts as a function of intensity was plotted with different temperature condition (Fig. 3b). Saturation phenomenon started at higher intensity of light (50 lux) for low temperature, which can be interpreted in terms of activation energy. In this work, we investigated the effect of wavelength and intensity of light in degradation of a-IGZO TFTs induced by NBIS. We discovered the existence of threshold light intensity and observed saturated behavior in Vth shifts under NBIS with respect to intensity. We will explain degradation mechanism in NBIS depending on wavelength and introduce new instability mechanism related to intensity of light. Figure 1

Acoustic communication is crucial to humans and many other tetrapods, including birds, frogs, crocodilians, and mammals. However, large-scale patterns in its evolution are largely unstudied. Here, we address several fundamental questions about the origins of acoustic communication in terrestrial vertebrates (tetrapods), using phylogenetic methods. We show that origins of acoustic communication are significantly associated with nocturnal activity. We find that acoustic communication does not increase diversification rates, a surprising result given the many speciation-focused studies of frog calls and bird songs. We also demonstrate that the presence of acoustic communication is strongly conserved over time. Finally, we find that acoustic communication evolved independently in most major tetrapod groups, often with remarkably ancient origins (~100–200 million years ago). Overall, we show that the role of ecology in shaping signal evolution applies to surprisingly deep timescales, whereas the role of signal evolution in diversification may not.

Mammals use variations in the length of day to anticipate environmental changes and time their reproduction. Light pollution, which affects day length perception, could lead to changes in biological functions. To explore the effects of light pollution on seasonal reproduction, we conducted an experimental study on a strict long-day breeder, the nocturnal gray mouse lemur (Microcebus murinus). Twelve females were randomly exposed to either a moonlight treatment or a light pollution treatment for 5 weeks during the transition from a short- to long-day photoperiod. Daily rhythms of locomotor activity and core temperature were recorded, and the occurrence of estrus and urinary 17-β-estradiol concentrations were monitored. In females exposed to light pollution, the first seasonal estrus occurred while they were still in a short-day photoperiod, 2 weeks earlier than in females exposed to moonlight. Moreover, the daily rhythms profiles of females exposed to light pollution showed significant changes that mimicked long-day acclimatization. This study demonstrates that light pollution can affect daily rhythms and the timing of seasonal estrus in a primate and suggests that functional changes in the circadian system may underlie the adverse effects of light pollution that are observed in wildlife.

BackgroundThe ascomycete fungus Zymoseptoria tritici (synonyms: Mycosphaerella graminicola, Septoria tritici) is a major pathogen of wheat that causes the economically important foliar disease Septoria tritici blotch. Despite its importance as a pathogen, little is known about the reaction of this fungus to light. To test for light responses, cultures of Z. tritici were grown in vitro for 16-h days under white, blue or red light, and their transcriptomes were compared with each other and to those obtained from control cultures grown in darkness.ResultsThere were major differences in gene expression with over 3400 genes upregulated in one or more of the light conditions compared to dark, and from 1909 to 2573 genes specifically upregulated in the dark compared to the individual light treatments. Differences between light treatments were lower, ranging from only 79 differentially expressed genes in the red versus blue comparison to 585 between white light and red. Many of the differentially expressed genes had no functional annotations. For those that did, analysis of the Gene Ontology (GO) terms showed that those related to metabolism were enriched in all three light treatments, while those related to growth and communication were more prevalent in the dark. Interestingly, genes for effectors that have been shown previously to be involved in pathogenicity also were upregulated in one or more of the light treatments, suggesting a possible role of light for infection.ConclusionsThis analysis shows that Z. tritici can sense and respond to light with a huge effect on transcript abundance. High proportions of differentially expressed genes with no functional annotations illuminates the huge gap in our understanding of light responses in this fungus. Differential expression of genes for effectors indicates that light could be important for pathogenicity; unknown effectors may show a similar pattern of transcription. A better understanding of the effects of light on pathogenicity and other biological processes of Z. tritici could help to manage Septoria tritici blotch in the future.

Irradiation with green light at night has great effects on the management of Conopomorpha sinensis and maintains favorable litchi fruit quality

In plant and photosynthesizing cyanobacteria, light is not only essential for photosynthesis but also damages the photosystem II (PSII) reaction centers. A repair cycle replenishes the PSII with newly synthesized subunits, and this process appears to require movement of the PSII from the grana (stacks of thylakoid membranes) to the stroma lamellae (membranous connections between the grana). Sarcina et al. used the cyanobacterium Synechococcus sp PCC7942 as a model system to study the mobility of PSII to different wavelengths of light. Chlorophyll is naturally fluorescent, with 80% of the fluorescence from PSII and 20% from PSI, so the mobility of PSII was monitored using fluorescence recovery after photobleaching (FRAP) of the chlorophyll. Exposure of the cells to red light stimulated the movement of chlorophyll, which in no light, blue light, or green light conditions was immobile. The movement in response to red light was dose dependent, with 3-second exposure triggering movement of 20% of the chlorophyll and 15-second exposure triggering a maximum movement of 60% of the chlorophyll. When entire cells were exposed to red light, the fluorescence became concentrated in discrete areas. Both red light and blue light cause photodamage to PSII; however, red light appears to engage the repair mechanism more quickly than does blue light. PSII damage was monitored by measuring oxygen production in response to blue or red light in the presence or absence of lincomycin, which inhibits protein synthesis and blocks the repair process. Blue light-treated cells exhibited sustained oxygen production (no loss in production for the first 20 minutes after exposure) in the absence of lincomycin, indicating rapid initiation of the repair process. Red light-treated cells showed loss of oxygen production within the first 10 minutes, and the repair cycle was engaged after 20 minutes. Thus, red light appears to produce a specific signal that alters PSII mobility, allowing it to effectively engage the repair cycle and maintain photosynthesis under conditions that cause photodamage. Exactly how the red light is perceived and how it stimulates PSII mobility remain to be determined. M. Sarcina, N. Bouzovitis, C. W. Mullineaux, Mobilization of photosystem II induced by intense red light in the cyanobacterium Synechococcus sp PCC7942. Plant Cell 18 , 457-464 (2006). [Abstract] [Full Text]

Introduction. Seedlings formation under controlled conditions is crucial for cultivating species like strawberry. With LED artificial lighting technology allowing greater control over light, variations in components such as wavelength and intensity can be manipulated to generate seedlings with different characteristics. However, there is a need to generate information for the development of precise and efficient light control practices. Objective. The evaluate strawberry seedling formation under different intensities of violet, blue, and red LED light. Material and methods. The study was conducted in 2020 at the Plant Genetics Laboratory of the Department of Agronomy at the Universidad de Guanajuato, Guanajuato, Mexico. Seeds from San Andreas variety fruits were collected, and seedlings were grown under violet, blue, and red LED light at high, medium, and low intensities. Color determinations of cotyledon area, Chroma saturation index, and Hue angle were performed. Additionally, physio-technical, chemical, and antioxidant activity variables were measured. Results. The most suitable treatments were high and medium intensity violet light, as well as high intensity blue light, with germination range exceeding 60 %. Seedlings did not elongate or thin out and exhibited the largest cotyledons areas and chlorophyll concentrations. Furthermore, these light treatments consumed, on average, 31.2 % less electrical energy. Conclusions. In addition to white light, the most suitable treatments for strawberry seedlings formation were high and medium intensity violet light, as well as high intensity blue light. It is suggested to evaluate violet and blue light treatments in other cultivars to confirm their positive effect on strawberry seedlings. Red light limited germination and showing higher antioxidant activity.