Temporal change of the aggregation response in Triatoma infestans

Adults and larvae of Triatoma infestans spend daylight hours assembled in shaded places. An assembling factor has been demonstrated in the excrement of this species. We analysed different aspects of the dynamics of the response of bugs. Recently fed insects do not aggregate around faeces. They start to show a significant assembling response from the 8th hour after feeding onwards. Just deposited faeces do not evoke assembling, but a significant rejection instead. This reaction switches 3 h after deposition, when the faeces become attractive to the insects. The attractiveness of faeces persists for about 10 days and can be recovered after this time by rehydration. These findings are discussed in relation to the biological role of faeces and the dynamics of the use of refuges by T. infestans.     

Colour perception of single and mixed monochromatic lights in the blowfly Lucilia cuprina

Colour perception of spectral lights and mixtures of two monochromatic lights of blue and yellow wavelengths was studied in the blowfly Lucilia cuprina by using a generalization test in which the fly had to compare these lights in memory with coloured papers (blue, green, yellow and red) represented in the test array. Flies trained to a monochromatic light in the wavelength range of 429–491 nm responded to blue; those trained to 502–511 nm to green; and those trained to 522–582 nm to yellow. The maximal generalization for blue was found at 429 nm and that for yellow at 543 nm. Flies trained to the mixtures responded neither to blue, green nor yellow, when the blue component was mixed with the yellow component in a ratio of approximately 1 3. It seems that the fly perceives the mixtures as a neutral or an achromatic light. Colour loci of coloured papers, spectral lights and mixtures of two monochromatic lights used formed blue, yellow and neutral clusters in a colour triangle with respect to generalization responses to test colours.     

Spectral responses of the tsetse fly, Glossina morsitans morsitans

Spectral responses of male Glossina morsitans morsitans Westw, were investigated using behavioural and electrophysiological techniques. Phototactic responses to monochromatic lights of different wavelengths but equivalent intensities (measured either in energy or quantal units) were tested in an apparatus which permitted the simultaneous presentation of pairs of lights to groups of flies. Near ultraviolet light was the most attractive, followed by blue and red, with green and far red light giving no significant responses above control levels. The spectral sensitivity of the compound eye was also determined from the electroretinogram (ERG) recorded from electrodes implanted in the eye which was stimulated with flashes of monochromatic light. Three areas of maximum sensitivity were found by this method in the UV, blue/green and red. The relationship between the behavioural and electrophysiological sensitivity characteristics is explained with reference to visual systems of other Diptera which have previously been described.     

光因子对石刁柏愈伤组织生长过程中蛋白质含量及酶活性变化的影响

在不同的光因子条件下,石刁柏愈伤组织的生长曲线均呈“Ｓ”型。愈伤组织的可溶性蛋白质含量以黄光最高,其次为蓝光、黑暗、白光、绿光、红光。在蓝光、黄光、红光条件上,愈伤组织的非特异性酯酶活性均出现３个峰、而绿光、白光、黑暗条件下则出现２个峰,以第２７天的峰植相比,其峰植的大小顺序为：黄光、蓝光、白光、红光、绿光、黑暗。除红光为２个过氧化物酶活性峰外,其他均为１个活性峰,其峰值的大小顺序是：黄光、蓝光、     

不同波长光照对罗汉果光合及生长影响

罗汉果试管苗在不同波长的LED(半导体)蓝(475±5nm)、黄(585±5nm)、红(660±5nm)及普通日光灯下培养,25d后观测发现,其外观的优劣依次为:蓝光>白光>红光>黄光;植株重量:蓝光>红光>黄光>白光;蓝光和白光下的植株叶大、色绿,植株矮壮,侧芽多;红光和黄光下的植株叶小、色黄绿,植株高、细、弯曲、节间长。测定罗汉果成熟叶片的吸收光谱,发现在波长380~500nm及660~680nm处有较强吸收。不同的光质下测定成熟叶片光合速率,大小依次为:红光>蓝光>白光>黄光。上述的各项试验表明,蓝光对罗汉果幼苗生长发育最好;红光和蓝光为成熟叶片光合作用的最佳光源。     

Near-infrared orientation of Mozambique tilapia Oreochromis mossambicus

Light plays a pivotal role in animal orientation. Aquatic animals face the problem that penetration of light in water is restricted through high attenuation which limits the use of visual cues. In pure water, blue and green light penetrates considerably deeper than red and infrared spectral components. Submicroscopic particles and coloured dissolved organic matter, however, may cause increased scattering and absorption of short-wave components of the solar spectrum, resulting in a relative increase of red and infrared illumination. Here we investigated the potential of near-infrared (NIR) light as a cue for swimming orientation of the African cichlid fish (Cichlidae) Oreochromis mossambicus. A high-throughput semi-automated video tracking assay was used to analyse innate behavioural NIR-sensitivity. Fish revealed a strong preference to swim in the direction of NIR light of a spectral range of 850-950nm at an irradiance similar to values typical of natural surface waters. Our study demonstrates the ability of teleost fish to sense NIR and use it for phototactic swimming orientation.     

Effects of Different Spectra from LED on the Growth,Development and Reproduction of <i>Arabidopsis thaliana</i>

Light is the major source of energy for plants and as such has a profound effect on plant growth and development. Red and blue lights have been considered to best drive photosynthetic metabolism and are beneficial for plant growth and development, and green light was seen as a signal to slow down or stop. In this study, Arabidopsis thaliana (Arabidopsis) was used to investigate the effects of red, blue and green lights on the growth and development of plants from seed germination to seeding. Results demonstrated that red light showed a promotion effect but blue light a prohibition one in most stages except for the flowering time in which the effect of each light was just reversed. When mixed with red or blue light, green light generally at least partially cancelled out the effects caused by each of them. Results also showed that the same number of photons the plant received could cause different effects and choosing the right combination of different color of lights is essential in both promoting the growth and development of plants and reducing the energy consumption of lighting in plant factory.     

Spectral information as an orientation cue in dung beetles

During the day, a non-uniform distribution of long and short wavelength light generates a colour gradient across the sky. This gradient could be used as a compass cue, particularly by animals such as dung beetles that rely primarily on celestial cues for orientation. Here, we tested if dung beetles can use spectral cues for orientation by presenting them with monochromatic (green and UV) light spots in an indoor arena. Beetles kept their original bearing when presented with a single light cue, green or UV, or when presented with both light cues set 180° apart. When either the UV or the green light was turned off after the beetles had set their bearing in the presence of both cues, they were still able to maintain their original bearing to the remaining light. However, if the beetles were presented with two identical green light spots set 180° apart, their ability to maintain their original bearing was impaired. In summary, our data show that ball-rolling beetles could potentially use the celestial chromatic gradient as a reference for orientation.     

The effect of light color on the nucleocytoplasmic and chloroplast cycle of the green chlorococcal algaScenedesmus obliquus

The color of light (white, red, blue, and green) had a significant effect on the growth and reproductive processes (both in the nucleocytoplasmic and chloroplast compartment of the cells) in synchronous cultures of Scenedesmus obliquus. This effect decreased in the order red > white > blue > green. In the same order, the light phase of the cell cycle (time when first autospores started to be released) was prolonged. The length of dark phase (time when 100 % of daughters were allowed to release from mothers) was not influenced and was the same for all colors. Critical cell size for cell division in green light was shifted to a smaller size (compared with cells grown in other lights) and so was the size of released daughters. The nuclear cycle was slowed in blue and even in green light, contrary to cells grown in red and white light. At the beginning of the cell cycle, one-nucleus daughters possess approximately 10 nucleoids; during the cell cycle their number doubled in all variants before the division of nuclei. Both events were delayed in cultures grown more slowly most markedly in green light. Smaller daughters in the green variant possessed a lower number of nucleoids. Motile cells released in continuous green or blue lights but not in red one were rarely observed.     

光质对绿豆幼苗叶片超微弱发光及叶绿素含量的影响

以绿豆幼苗为试材,测定其叶片超弱发光(UBE)及叶绿素含量在不同光质条件下的变化,并探讨两者之间的关系.结果表明,生长在不同光质下绿豆幼苗叶片的UBE及延迟发光衰减参数1/P都随着其生长不断增强,且生长在白光下绿豆幼苗的UBE是生长在其他光质(红、黄、蓝、绿)下幼苗的2倍以上,而红光、黄光和绿光处理之间无显著差异;生长在白光下的绿豆幼苗叶片叶绿素含量显著高于红、黄、蓝、绿光处理幼苗,而红光和黄光处理又显著高于蓝光和绿光处理.研究发现,光质对绿豆幼苗叶片超弱发光和叶绿素含量影响相似,绿豆幼苗叶片超弱发光可能与叶绿体的发育和光合作用有关.     

Role of Vision and Mechanoreception in Bed Bug,Cimex lectularius L. Behavior

The role of olfactory cues such as carbon dioxide, pheromones, and kairomones in bed bug, Cimex lectularius L. behavior has been demonstrated. However, the role of vision and mechanoreception in bed bug behavior is poorly understood. We investigated bed bug vision by determining their responses to different colors, vertical objects, and their ability to detect colors and vertical objects under low and complete dark conditions. Results show black and red paper harborages are preferred compared to yellow, green, blue, and white harborages. A bed bug trapping device with a black or red exterior surface was significantly more attractive to bed bugs than that with a white exterior surface. Bed bugs exhibited strong orientation behavior toward vertical objects. The height (15 vs. 30 cm tall) and color (brown vs. black) of the vertical object had no significant effect on orientation behavior of bed bugs. Bed bugs could differentiate color and detect vertical objects at very low background light conditions, but not in complete darkness. Bed bug preference to different substrate textures (mechanoreception) was also explored. Bed bugs preferred dyed tape compared to painted tape, textured painted plastic, and felt. These results revealed that substrate color, presence of vertical objects, and substrate texture affect host-seeking and harborage-searching behavior of bed bugs. Bed bugs may use a combination of vision, mechanoreception, and chemoreception to locate hosts and seek harborages.     

The effect of light quality on leaf production and development of in vitro-cultured plants of Alternanthera brasiliana Kuntze

We investigated the influence of light quality on the leaf development of Alternanthera brasiliana Kuntze (Amaranthaceae) grown in vitro. Growth parameters including specific leaf mass, thickness, and leaf density were lowest in plants grown under red light. Blue light induced the largest number of leaves/plant, and the largest thickness and area of the leafblade. Green and red lights induced the smallest leaf areas. The thickness of the abaxial-face epidermis and spongy parenchyma of the plants was significantly reduced in plants grown under red light. The thickness of the palisade parenchyma and upper epidermis were significantly increased in plants grown under blue light, compared to the other fluorescent-light treatments. The specific spectral band also influenced the differentiation of mesophyll cells. In the dark and under red light, the mesophyll was homogenous; and in the dark and under green light, the leaves were more compact. Under blue light, the cells displayed the characteristic palisade morphology. The results showed that the increase of a specific parenchyma type was related to a specific spectral band. All spectral-quality treatments reduced the numbers of stomata and trichomes. The results for green light were in some respects similar to those for red light, and in other respects similar to those for blue light, probably because phytochromes and cryptochromes are green-light receptors. This study indicated that Alternanthera plants have strong morphological plasticity induced by light. The results suggest that high-quality Alternanthera can be achieved by culturing the plants in vitro under a combination of blue and red light.     

LED Light-Induced ROS Differentially Regulates Focal Adhesion Kinase Activity in HaCaT Cell Viability

In this study, changes in cell signaling mechanisms in skin cells induced by various wavelengths and intensities of light-emitting diodes (LED) were investigated, focusing on the activity of focal adhesion kinase (FAK) in particular. We examined the effect of LED irradiation on cell survival, the generation of intracellular reactive oxygen species (ROS), and the activity of various cell-signaling proteins. Red LED light increased cell viability at all intensities, whereas strong green and blue LED light reduced cell viability, and this effect was reversed by NAC or DPI treatment. Red LED light caused an increase in ROS formation according to the increase in the intensity of the LED light, and green and blue LED lights led to sharp increases in ROS formation. In the initial reaction to LEDs, red LED light only increased the phosphorylation of FAK and extracellular-signal regulated protein kinase (ERK), whereas green and blue LED lights increased the phosphorylation of inhibitory-κB Kinase α (IKKα), c-jun N-terminal kinase (JNK), and p38. The phosphorylation of these intracellular proteins was reduced via FAK inhibitor, NAC, and DPI treatments. Even after 24 h of LED irradiation, the activity of FAK and ERK appeared in cells treated with red LED light but did not appear in cells treated with green and blue LED lights. Furthermore, the activity of caspase-3 was confirmed along with cell detachment. Therefore, our results suggest that red LED light induced mitogenic effects via low levels of ROS–FAK–ERK, while green and blue LED lights induced cytotoxic effects via cellular stress and apoptosis signaling resulting from high levels of ROS.     

Assembly of LH2 light-harvesting complexes in Rhodopseudomonas palustris cells illuminated by blue and red light

We investigated the formation of the B800-850 complex in cells of the bacterium Rhodopseudomonas palustris AB illuminated by red and blue light under anaerobic growth conditions. Under red illumination, the B800-850 complex was assembled with a reduced absorption band at 850 nm. The results of re-electrophoresis of the B800-850 complex and oxidation in the presence of potassium iridate suggest its heterogeneity. It may be a mixture of two complexes (B800 and B800-850). The B800-850 complex lacks the capacity for conformational transitions if assembled under blue illumination. Accordingly, the light-harvesting complex assembled in the blue light contains polypeptides that are not synthesized under normal conditions or at increased or decreased light intensities. The mechanism of regulation of the synthesis of the polypeptides of light-harvesting B800-850 complex and its dependence on the spectral composition of the light is discussed.     

Effects of light quality on the chloroplastic ultrastructure and photosynthetic characteristics of cucumber seedlings

To understand how light quality influences plant photosynthesis, we investigated chloroplastic ultrastructure, chlorophyll fluorescence and photosynthetic parameters, Rubisco and chlorophyll content and photosynthesis-related genes expression in cucumber seedlings exposed to different light qualities: white, red, blue, yellow and green lights with the same photosynthetic photon flux density of 100 μmol m^?2 s^?1. The results revealed that plant growth, CO₂ assimilation rate and chlorophyll content were significantly reduced in the seedlings grown under red, blue, yellow and green lights as compared with those grown under white light, but each monochromatic light played its special role in regulating plant morphogenesis and photosynthesis. Seedling leaves were thickened and slightly curled; Rubisco biosynthesis, expression of the rca, rbcS and rbcL, the maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII electron transport (Ф_PSII) were all increased in seedlings grown under blue light as compared with those grown under white light. Furthermore, the photosynthetic rate of seedlings grown under blue light was significantly increased, and leaf number and chlorophyll content of seedlings grown under red light were increased as compared with those exposed to other monochromatic lights. On the contrary, the seedlings grown under yellow and green lights were dwarf with the new leaves etiolated. Moreover, photosynthesis, Rubisco biosynthesis and relative gene expression were greatly decreased in seedlings grown under yellow and green light, but chloroplast structural features were less influenced. Interestingly, the Fv/Fm, Ф_PSII value and chlorophyll content of the seedlings grown under green light were much higher than those grown under yellow light.     

Spectral sensitivity of the photonegative reaction of the blood-sucking bug Triatoma infestans (Heteroptera: Reduviidae)

We studied the spectral sensitivity of the visual system of the blood-sucking bug Triatoma infestans, one of the main vectors of Chagas Disease in South America. We quantified the photonegative reaction of this insect in a rectangular arena, half of which was kept dark and the other half illuminated with various intensities of different monochromatic lights (or broadband stimuli for λ>665 nm). As a behavioral parameter of the photonegative response, we measured the time each insect spent in the dark half of the arena. We found that low intensity levels (under 0.06 μW/cm²) of monochromatic lights of 397, 458, 499, and 555 nm evoked a statistically significant (i.e., different from that of control groups) photonegative reaction. Insects were less sensitive to monochromatic lights of 357 nm (UV) and 621 nm (dark orange), and to broadband stimuli in the red part of the spectrum (665–695 nm). These findings indicate that the visual system of T. infestans is sensitive to broader regions of the spectrum than those previously reported.     

Induction of metamorphosis in the sea urchin Holopneustes purpurascens by a metabolite complex from the algal host Delisea pulchra

Most benthic invertebrates have complex life cycles with planktonic larvae that return to the substratum to settle and metamorphose into a benthic stage. Although naturally produced chemical cues have long been thought to be important for the settlement or metamorphosis of invertebrate larvae, few ecologically relevant chemical cues have been clearly identified. The marine echinoid Holopneustes purpurascens has a complex life cycle, with a planktonic, nonfeeding dispersive larva that metamorphoses into a benthic stage that lives in the canopy of subtidal benthic algae such as the red alga Delisea pulchra and the kelp Ecklonia radiata. Recently recruited juveniles are found primarily on D. pulchra, and we hypothesized that this was in response to a chemical cue produced by this alga. Competent larvae metamorphosed in the presence of D. pulchra, or seawater surrounding this alga, but not in response to the presence of E. radiata or its extracts. A cue for metamorphosis was isolated and characterized from D. pulchra and found to be a water-soluble complex of the sugar floridoside and isethionic acid in a 1:1 molar ratio. The floridoside-isethionic acid complex also triggered settlement in H. purpurascens; however, this response was less specific than metamorphosis and was reversible. Larvae of H. purpurascens also metamorphosed in the presence of several other species of red, but not brown or green, algae from their habitat. Floridoside is found only in red algae, suggesting that the floridoside-isethionic acid complex may be acting as a cue for metamorphosis in other red algae as well as in D. pulchra.     

Synergistic influence of CuO nanoparticles and spectral lights transforms biomass,antioxidative response,and antioxidants in Brassica nigra

Some nanoparticles (NPs) have photocatalytic and photodynamic properties that change on variation in wavelength of light carrying different energies. To access photo-dynamic toxicity of CuO NPs, Brassica nigra seeds were in vitro grown on CuO NPs supplemented media under the exposure of five different spectral lights (white, blue, red, yellow and green). Light wavelength significantly affected shoot and root length and fresh weight of B. nigra and CuO NPs exerted different level of toxicity under these lights. Noteworthy variations were observed in free radical scavenging activity, total antioxidantive response and total reducing power potential when plants were grown in presence of NPs and spectral lights. Significant variations in total phenolics and flavonoids contents were observed in shoots as compared with roots. HPLC analysis presented variation in phenolics in shoots extracts under synergistic influence of NPs and light regime. The study shows that nanoparticles exert different level of toxicity under different wavelengths of lights. Resultantly plants show variations in morphological and biochemical responses. Consequently secondary metabolites produce in plants at varying concentrations to mitigate nanotoxicity under photodynamic response.

     

Spectral preferences of Lycorma delicatula (Hemiptera: Fulgoridae)

Many insects prefer lights with certain spectral properties, and such preferences may be associated with behavioral contexts such as mating, host finding or dispersal. Lycorma delicatula (Hemiptera: Fulgoridae) is a newly invasive species in Korea and is spreading rapidly. It is diurnal and may rely on visual cues for orientation. We conducted a series of three phototaxis experiments to understand spectral preferences in L. delicatula: light/dark choice, UV/white light choice, and color preference experiments. Nymphs of the third and final stages as well as adults were used for these experiments. In the light/dark choice, the orientation of L. delicatula was bimodal between the white light and darkness, for all stages and both sexes. In a choice of UV (395–410 nm wavelengths) vs. white light, L. delicatula of both sexes and all stages preferred the UV light. In the color preference experiment where insects had a choice of four colors in a circular arena, L. delicatula stayed significantly longer in the blue light than in white, yellow or green lights. Overall, nymphs and adults of L. delicatula oriented toward lights with shorter wavelengths, and this orientation was consistent throughout all stages, regardless of sex. It is necessary to investigate the behavioral contexts under which L. delicatula prefers the UV and blue lights.     

Assembly of LH2 light-harvesting complexes in Rhodopseudomonas palustris cells illuminated by blue and red light

We investigated the formation of the B800-850 complex in cells of the bacterium Rhodopseudomonas palustris AB illuminated by red and blue light under anaerobic growth conditions. Under red illumination, the B800-850 complex was assembled with a reduced absorption band at 850 nm. The results of re-electrophoresis of the B800-850 complex and oxidation in the presence of potassium iridate suggest its heterogeneity. It may be a mixture of two complexes (B800 and B800-850). The B800-850 complex lacks the capacity for conformational transitions if assembled under blue illumination. Accordingly, the light-harvesting complex assembled in the blue light contains polypeptides that are not synthesized under normal conditions or at increased or decreased light intensities. The mechanism of regulation of the synthesis of the polypeptides of light-harvesting the B800-850 complex and its dependence on the spectral composition of the light is discussed.