Middle Wavelength Research Articles

Shining new light on naupliar eyes: A novel molecular phylogeny for Pleuromamma (Family: Metridinidae) and the characterization of luciferase and opsin expression

Pleuromamma (Giesbrecht, 1898) is a cosmopolitan genus of metridinid copepods, with species that perform remarkable diel vertical migrations (DVM) and emit a bioluminescent secretion when disturbed that varies both spectrally and kinetically. Copepod bioluminescence is autogenic and uses luciferase enzymes that catalyze a luciferin, coelenterazine, to produce light. Pleuromamma possess naupliar eyes, relatively simple photosensitive structures used for many visually-guided behaviors. Yet the fundamental molecular unit for vision, the opsin protein, has not been previously described for the family. The light producers and detectors are important to study because DVM is a behavior that mediates significant active elemental fluxes between the upper ocean and midwaters across vast stretches of oceanic habitat, and DVM is guided by visual behaviors, with animals tracking an isolume. Here we provide the first fully resolved molecular phylogeny for Pleuromamma (Family: Metridinidae) and describe the luciferase and opsin gene diversity and expression using de novo assembled transcriptomes. We successfully sequenced and assembled transcriptomes for 10 of 11 described species of Pleuromamma as well as two other metridinid species: Metridia longa and Gaussia princeps. In all species, we obtained coding sequences of one putative rhabdomeric middle wavelength sensitive visual opsin gene, as well as several non-visual opsins – a c-type pteropsin and a tetra-opsin type peropsin. Furthermore, Pleuromamma express luciferases from each of two main evolutionary clades (Luc1 and Luc2), and a single paralog (Luc2a) dominates expression throughout the group. The variation in luciferase number, sequence, and expression among species could lead to different spectral and kinetic properties of bioluminescence and aid in congener recognition.

Reducing reflection of down-shifting solar cells through scattering by particles

The improvement of down-shifting solar cells through reducing the reflection in short wavelength range by scattering is investigated experimentally and theoretically. Such down-shifting solar cells are fabricated by doping Y2O3 particles into down-shifting ethylene vinyl acetate films with CaAlSiN3:Eu2+ phosphors. Experimental results show that the scattering of Y2O3 particles can reduce the reflection of the down-shifting solar cells in the wavelength below 450 nm. It can be attributed to two reasons. The first is that the backscattering in the short wavelength is weaker than that in the middle and long wavelength. The second is that the scattering by Y2O3 particles allows more light reach the phosphors and increases their absorption. This means that more photons with poor spectral responses can be converted into the photons with better spectral responses. This work provides a way to realize simultaneously strengthening the down-shifting effect and suppressing the phosphor-induced reflection and can be used to further improve the down-shifting solar cells.

Ozone and aerosol optical depth retrievals using the ultraviolet multi-filter rotating shadow-band radiometer

Abstract. The ultraviolet multi-filter rotating shadow-band radiometer (UV-MFRSR) is a seven-channel radiometer with narrowband filters centered between wavelengths 300 and 368 nm. Four of the middle wavelengths in this device are near those used in the Dobson spectrometer to retrieve ozone column abundance. In this paper measurements from Mauna Loa Observatory (MLO) were used first to calibrate the instrument using the Langley plot method and subsequently to derive column ozone and aerosol optical depths. The ozone derived from the UV-MFRSR was compared to the ozone measured by a Dobson spectrophotometer that operates daily at the MLO, resulting in column values within about 1 DU on average for 43 d in 2018. The aerosol optical depth (AOD) retrievals are more challenging. Generally, the AOD increases with wavelength between 305 and 332 nm, not what is expected given the typical AOD wavelength dependence at visible wavelengths. An example of this behavior is discussed, and research by others is cited that indicates similar behavior at these wavelengths, at least for the low-aerosol-optical-depth conditions encountered at high-altitude sites.

Knockout of SWS2 in zebrafish (Danio rerio) reveals its roles in feeding and phototactic behaviors

Common ancestor of vertebrates had four cone opsin subfamilies to obtain color vision: ultraviolet-sensitive (SWS1), blue-sensitive (SWS2), middle wavelength sensitive (RH2) and long wavelength sensitive (LWS). Nevertheless, eutherian mammals had lost the SWS2 and RH2 opsins during their nocturnal lifestyle. Many studies had demonstrated the role of SWS1 and LWS cones in feeding, mate choice and skin pigment cell formation. However, the role of SWS2 and RH2 cones remain elusive. In the present study, we used an ideal model visual system, zebrafish, which still have the four cone opsins, to generate a SWS2 knockout zebrafish line. Through various behavioral test, we found that sws2-/- zebrafish larvae exhibited increased food intake compared with WT. Additionally, there were significantly increased the gene expression of phototransduction pathways in sws2-/- zebrafish larvae. Compared to WT, mutant zebrafish showed weaker phototaxis of red light and changed sensitivity of yellow, red and blue lights. But both mutant and WT zebrafish preferred the red light than other wavelengths of light. Taken together, we proposed that SWS2 cone is not necessary for feeding and phototaxis in zebrafish.

UV Absorption Spectroscopy of the Conformer-Dependent Reactivity of the Four Carbon Criegee Intermediate of Methyl Vinyl Ketone Oxide: An Ab initio Quantum Dynamics Study.

An extended theoretical analysis of the photodissociation dynamics of the four-carbon Criegee intermediate (CH2═CH(CH3)COO) or methyl vinyl ketone oxide, which has four conformers, following excitation to the B state, is presented. Our analysis relies on multireference electronic wave functions combined with a wavepacket propagation treatment for the two coupled B1A' and C1A' electronic states and two nuclear degrees of freedom. For each conformer, the 2D model depends on potential energy surfaces (PESs) along the O-O and C-O-O bending modes for the two lowest excited states, B1A' and C1A', and is sufficiently accurate to reproduce the experimental B1A' ← X1A' absorption spectrum with unprecedented accuracy. It is found that the roles of each conformer are essential in producing a cumulative spectrum, which is close to the recent experimental spectrum. The anti-trans and anti-cis conformers make contributions at the longer and shorter wavelengths of the cumulative spectrum, respectively, while the syn-cis and syn-trans conformers have contributions in the middle wavelength range of the cumulative spectrum of MVK-oxide. The existence of a deep well for each conformer on the PESs of the (diabatic) B state causes a considerable amount of the wavepacket to be reflected by the B state wells, which can explain the oscillatory structures appearing in the long wavelength range of 360-480 nm of the spectrum. The weakly avoided crossings between the B-state and C-state PESs of each conformer appearing within the range of 2.80-3.08 eV excitation energy cause considerable disturbance in the vibronic fine structure of the bands. The results give novel insight into the complex interactions governing this intriguing process.

Comprehensive experimental study of NBνN barrier structures based on n-HgCdTe MBE for detection in MWIR and LWIR spectra

This work is devoted to a comprehensive experimental study of the electrical and photoelectric characteristics of barrier photosensitive structures in the NBνN configuration based on n-HgCdTe (MCT). Seven different types of photosensitive structures for middle wavelength (MWIR) and long wavelength (LWIR) infrared (IR) radiation ranges grown by molecular beam epitaxy (MBE) have been studied by complex conductivity spectroscopy method. The current-voltage characteristics (CVC) were measured both in the dark and in the presence of illumination. Based on the measured dependences of the dark current density on temperature and the ratio of the perimeter to the area of the structure, the dominant contribution of the bulk current component compared to the surface component for the MWIR structure (x ∼ 0.30) was established. This fact was confirmed by the value of the activation energy (from the Arrhenius plots) corresponding to the band gap. The results of frequency measurements of the differential conductivity of MIS structures based on NBνN also give a close activation energy, which corresponds to the diffusion limitation. LWIR structures (x ∼ 0.20) are characterized by an increase in the contribution of the surface leakage current in the total dark current. In this case, the activation energy determined from MIS measurements exceeds the band gap of the ν-layer, which is associated with the presence of an energy barrier for holes in the valence band. It is shown that if the problem of passivation of mesa structures is solved, it is possible to fabricate efficient MWIR and LWIR nBn, NBνN detectors based on MBE HgCdTe with high threshold parameters.

Fabrication of a Composite Film Optic with High Transmittance in Vis and IR Regions for an Optical System

In this study, a lightweight composite polyimide film optic with antireflective coating was prepared using an ion-beam-assisted reactive sputtering method. It exhibited high transmittance in visible (87%, 0.5~0.8 μm), short (86%, 1.8~2.7 μm) and middle (78%, 3.3~5.4 μm) wavelength infrared regions. Additionally, it also showed great optical homogeneity (0.006 λ in RMS and 0.034 λ in PV, λ = 632.8 nm) with smooth surfaces (RMS = 0.786 nm). The thermal stability of the polyimide film was also effectively maintained after the antireflective coating. At the same time, by utilizing the hydrophobic properties of coating materials (Ta2O5/SiO2), the antireflective layer acted as an effective water barrier on the film surface to reduce the water absorption.

Effect of down-shifting phosphor particles on crystalline silicon solar cells

Introducing down-shifting phosphor particles onto solar cells can improve their spectral response to short wavelength photons, but it also leads to the rise of reflection in middle and long wavelength range due to the scattering by phosphor particles. In this work, the down-shifting solar cells are fabricated by packaging crystalline silicon solar cells with ethylene vinyl acetate (EVA) films which include different concentration of down-shifting Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor particles. Experimental result shows that the increasing concentration of YAG:Ce phosphors strengthens the down-shifting effect and makes the reflection rise. The competition between the down-shifting effect and the reflection results in the best improvement of the solar cells when the phosphor's concentration is 0.7%. The optical ray-tracing simulations clarify that the packaged solar cell with YAG:Ce absorbs less photons than those without YAG:Ce, but their conversion efficiency is higher than those without YAG:Ce. This indicates that the penetration depth of the short wavelength photons is responsible for the poorer spectral response of the solar cells in the short wavelength range.

High performance InAs0.91Sb0.09 MWIR detectors with an AlAs1-ySby graded barrier

InAs0.91Sb0.09 barrier detectors are an important candidate in realizing high operating temperature middle wavelength infrared (MWIR) photodetectors. Here, an AlAs1-ySby graded barrier layer with linear Sb composition varying from y = 1 to 0.92 is utilized to improve the extraction of photo-generated minority carriers from an InAs0.91Sb0.09 absorber layer. With the modification of valance band misalignment between the absorber and barrier layers, although a hole barrier between AlAs0.08Sb0.92 and InAs0.91Sb0.09 layers exists, the photo-generated holes can be effectively extracted. At 150 K and under zero bias voltage, the maximum quantum efficiency of the devices with a graded barrier reaches ∼56 %, which is much higher than that of the device with a uniform AlAs0.08Sb0.92 barrier. Benefiting from the low dark current density at small reverse bias voltages, a maximum specific detectivity (D*) ∼6.19 × 1011 cm⋅Hz1/2/W is realized at zero bias voltage, which is 50 % higher than the maximum D* ∼4.26 × 1011 cm⋅Hz1/2/W of the uniform barrier device operated at −150 mV bias voltage.

Design of MWIR hyperspectral imagers based on acousto-optic tunable filters

Thermal infrared hyperspectral imagers have significant application values in the field of space optics. However, it is very difficult to obtain the spectral data cube and temperature field information of fast moving targets in a short time. An acousto-optic tunable filter (AOTF) has many advantages, such as fast tuning speed, light weight and no moving parts. It can obtain thermal infrared hyperspectral images of a fast-moving target in a very short integration time. In this paper, a collimating optical system is obtained by splicing optical path a telescope and a secondary imaging mirror. A middle wavelength infrared (MWIR) AOTF is introduced into the collimating optical system to modulate the spectrum and obtain thermal infrared hyperspectral images. The system with a focal length of 18 mm, a relative aperture of 1/2, a field of view (FOV) of 8°, a spectral resolution of 30.08 nm at 4 µm and a 100% cold diaphragm efficiency achieving is taken as a design example. The design results show that the modulation transfer function (MTF) of the system is greater than 0.6 at the Nyquist space frequency of 17 lp/mm, and the imaging quality is close to the diffraction limit. Finally, we develop a prototype of MWIR hyperspectral imager based on AOTFs and do experiments to prove its feasibility.

Influence of location, season and time of day on the spectral composition of ambient light: Investigation for application in myopia.

Given the possible role of spectral composition of light and myopia, this study aimed at investigating the variation in the spectral composition of ambient light in different (a) outdoor/indoor locations, (b) time of a day and (c) seasons. The spectral power distribution (SPD), categorised into short (380-500 nm), middle (505-565 nm) and long wavelengths (625-780 nm), was recorded using a handheld spectrometer at three outdoor locations ('open playground', 'under shade of tree' and 'canopy') and three indoor locations ('room with multiple windows', 'closed room' and 'closed corridor'). Readings were taken at five different time points (3-h intervals between 6:30 and 18:00 hours) on two days, each during the summer and monsoon seasons. The overall median SPD (IQR [25th-75th percentile] W/nm/m2 ) across the three outdoor locations (0.11 [0.09, 0.12]) was 157 times higher than that of the indoor locations (0.0007 [0.0001, 0.001]). Considerable locational, diurnal and seasonal variation was observed in the distribution of the median SPD value, with the highest value being recorded in the 'open playground' (0.27 [0.21, 0.28]) followed by 'under shade of tree' (0.083 [0.074, 0.09]), 'canopy' (0.014 [0.012, 0.015]) and 'room with multiple windows' (0.023 [0.015, 0.028]). The relative percentage composition of short, middle and long wavelengths was similar in both the outdoor and indoor locations, with the proportion of middle wavelengths significantly higher (p< 0.01) than short and long wavelengths in all the locations, except 'canopy'. Irrespective of variation in SPD values with location, time, day and season, outdoor locations always exhibited significantly higher spectral power than indoor locations. The relative percentage composition of short, middle and long wavelengths of light was similar across all locations. These findings establish a foundation for future research to understand the relationship between spectral power and the development of myopia.

Room-temperature InAsSb pBin detectors for mid-infrared application

InAs-based compound is a direct, narrow bandgap III-V semiconductor with high carrier mobility and an attractive optoelectronic device candidate for application in the infrared region. Herein, a pBin InAsSb photodetector structure has been grown successfully by cost-effective Liquid Phase Epitaxy (LPE) technique. The introduction of high quality InAsSbP barrier can effectively reduce dark current, which leads to good room-temperature detector performances. A clear room-temperature photoresponse (1.6 A/W, corresponding to 50% external quantum efficiency) in the middle wavelength infrared (MWIR) range has been achieved. In addition, due to nearly zero valence band offset at zero bias, InAsSbP barrier blocks the electron dark current, while allowing the photogenerated holes to flow to the contact, which dramatically improved the performance of the detector without a turn-on operating bias. This self-powered device can reduce the size and weight of the system, and can be further developed towards the optoelectronic integrated nanosystems. The combination of the good room-temperature performance, self-powered design, and cost-effective fabrication suggests that this pBin InAsSb photodetector has wide application prospect in both military and civilian field.

Cerebral achromatopsia

AbstractChromatic sensitivity was assessed in patients with pregeniculate and postgeniculate lesions. We examine changes in central vision along at foveal fixation and in each of the four paracentral quadrants of the visual field using the Colour Assessment and Diagnosis (CAD) test, a dynamic luminance contrast masking technique that isolates the use of Red / Green (RG) and Yellow / Blue (YB) colour signals. Because the extraction of colour signals in early visual processing involves opponent mechanisms, subjects with congenital RG loss of sensitivity exhibit symmetric increase in thresholds towards the long wavelength (“red”) and middle wavelength (“green”) regions of the spectrum locus. This is also frequently the case with acquired loss of chromatic sensitivity as a result of retinal or optic nerve disease. The findings from this study represent an exception to this rule. The patients investigated showed a marked asymmetry in colour thresholds. The study reveals how discrete, localized damage to visual pathways can cause selective loss of visual function and how the latter varies with retinal topography.The 36 pregeniculate patients investigated exhibited impairment in both RG and YB. Loss of colour vision was symmetrical for both RG and YB discrimination. Some pregeniculate patients exhibited substantial loss of colour vision in areas where perimetric loss was largely absent. All quadrants revealed similar symmetric loss of colour sensitivity.In 23 patients with postgeniculate lesions, patients with pre‐striate damage exhibited symmetric loss of chromatic sensitivity which affected either one or both chromatic mechanisms. Striate or extra‐striate lesions tended to exhibit general loss of colour vision within the area identified by visual field testing. More specific chromatic loss was associated with less impaired areas that were often normal on perimetric testing. Some patients with striate or extra‐striate lesions presented with asymmetric chromatic loss for one or more colour categories. When striate or extra‐striate lesions were also accompanied by underlying pre‐striate damage, chromatic sensitivity loss was always symmetric.The findings from this study show that the loss of chromatic sensitivity in cerebral achromatopsia depends strongly on the exact location and extent of the lesion with significant variation over the visual field. The same subject can exhibit loss of chromatic sensitivity that is either RG or YB specific, but also, spatially localized, non‐opponent loss of sensitivity for primary colours.

Chromatic organization of retinal photoreceptors during eye migration of Atlantic halibut (Hippoglossus hippoglossus).

The retinas of fishes often have single and double cone photoreceptors that are organized in lattice-like mosaics. In flatfishes experiencing eye migration (i.e., the metamorphic process whereby one eye migrates to the other side of the head), the hexagonal lattice of single cones present in the larva undergoes major restructuring resulting in a dominant square mosaic postmetamorphosis consisting of four double cones surrounding each single cone. The expression of different opsin types during eye migration has not been examined despite its importance in understanding photoreceptor plasticity and whether cell fate (in terms of spectral phenotype) could influence square mosaic formation. Here, we probed the retina of Atlantic halibut undergoing eye migration for opsin expression using two antibodies, AHblue and AB5407, that labeled short wavelength sensitive 2 (SWS2) opsin and longer wavelength (predominantly middle wavelength sensitive, RH2) opsins, respectively. Throughout the retina, double and triple cones labeled with AB5407 exclusively, whereas the vast majority of single cones labeled with AHblue. A minority (<5%) of single cones in the square mosaic of the centroventral retina labeled with AB5407. In regions of mosaic transition and near peripheral growth zones, some single cones co-expressed at least two opsins as they labeled with both antibodies. Short wavelength (SWS2 expressing, or S) cones formed a nonrandom mosaic gradient from central to dorsal retina in a region dominated by the larval single cone mosaic. Our results demonstrate the expression of at least two opsins throughout the postmetamorphic retina and suggest opsin switching as a mechanism to create new cone spectral phenotypes. In addition, the S cone gradient at the onset of eye migration may underlie a plastic, cell induction mechanism by which a cone's phenotype determines that of its neighbors and the formation of the square mosaic.

Crustacean conundrums: a review of opsin diversity and evolution.

Knowledge of crustacean vision is lacking compared to the more well-studied vertebrates and insects. While crustacean visual systems are typically conserved morphologically, the molecular components (i.e. opsins) remain understudied. This review aims to characterize opsin diversity across crustacean lineages for an integrated view of visual system evolution. Using publicly available data from 95 species, we identified opsin sequences and classified them by clade. Our analysis produced 485 putative visual opsins and 141 non-visual opsins. The visual opsins were separated into six clades: long wavelength sensitive (LWS), middle wavelength sensitive (MWS) 1 and 2, short wavelength or ultraviolet sensitive (SWS/UVS) and a clade of thecostracan opsins, with multiple LWS and MWS opsin copies observed. The SWS/UVS opsins were relatively conserved in most species. The crustacean classes Cephalocarida, Remipedia and Hexanauplia exhibited reduced visual opsin diversity compared to others, with the malacostracan decapods having the highest opsin diversity. Non-visual opsins were identified from all investigated classes except Cephalocarida. Additionally, a novel clade of non-visual crustacean-specific, R-type opsins (Rc) was discovered. This review aims to provide a framework for future research on crustacean vision, with an emphasis on the need for more work in spectral characterization and molecular analysis. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'.

АЛГОРИТМИЧЕСКИЙ МЕТОД РАСЧЕТА ОТРАЖЕНИЯ И ПРОХОЖДЕНИЯ ВОЛНЫ ЧЕРЕЗ МНОГОСЛОЙНУЮ СТРУКТУРУ. ЧАСТЬ 2. ПАДЕНИЕ ВОЛНЫ НА НАКЛОННЫЙ БАРЬЕР

On the foundation of calculation matrix algorithm of single-dimension wave reflection and passage through multi-layer structure the task about incidence of wave on the inclined barrier is solved. The barrier is presented in the form of step-structure which is consisted of uniform parts divided by boundaries. As a most parameter which determines the wave properties on the single uniform part it is established the wave number. The inclined barrier corresponds to linear increasing of wave number by step way. It is shown that the reflection coefficient by maxima length of barrier is sufficient small and increases to maxima when the length of barrier goes to zero. In this case the dependence of passing coefficient from the barrier length has mirror-symmetrical character relatively the level of 0,5 relative units. The sum of reflection and passage coefficients in all cases is equal to unit. By the character of reflection coefficient dependence from wave number value it is selected three regions: first – when the dependence is regular without the oscillations; second – when dependence is regular and oscillating; third – when dependence has non-regular oscillating character which approach to chaotic so much the high of step is more. As the parameter which divides the regions it is found two critical values of wave number: first – which correspond to transition from smooth dependence to oscillating; second – which correspond to transition from oscillating dependence to chaotic. It is found that the first critical value of wave number step correspond to equality between middle length of wave and whole length of barrier. The second critical value of wave number step correspond to equality between middle length of wave and length of unit step along the barrier length. Fir the interpretation of observed phenomenon the supposition is voiced about its interference origin. It is investigated the dependencies both critical step wave number values from initial length of barrier. It is shown that both dependencies in the high precision (parts of percent) follow inverse ratio to initial length of barrier and different level of curves is determined by the alignment of barrier length and length of its unit step along the barrier length. The connection between initial barrier length and value of unit step along the barrier length. It is found the invariant which is equal to half of relation of initial barrier length to whole length of structure multiplied to value of wave number step. The reflection and passage of wave by large length of structure is investigated. It is found the periodic character of reflection and passage dependencies from length of barrier. On the dependencies is found the sharp peaks which high is approach to maximum corresponding to zero length of barrier. It is found that the distance between peaks along the barrier length corresponds to inverse ratio to wave number step. It is found that the value of barrier length period which correspond to different peaks to a great extent (about two orders) exceeds the middle wave length which is determined the whole over-fall of wave number in the region of whole barrier. For the interpretation of periodic character these dependencies of reflection and passage coefficients from barrier length the model of successive re-reflections is proposed. It is found that the specific of out-coming from structure waves is achieved by coincidence of doubled barrier length with length of propagating wave.

Standard CMOS Process Integrated Silicon-Based Ultraviolet-Infrared Complementary Sensor

This study proposes a new ultraviolet-infrared (UV-Ir) compatible sensor fabricated using the standard CMOS process. The concept is verified through a numerical simulation, wherein the standard CMOS process parameters used are evaluated. The proposed sensor is an extension of a previously proposed RGB sensor designed on the standard CMOS process, and calculating the current ratio enables the detection of UV with high sensitivity. In addition, the use of current rectification eliminates the short to middle wavelength region and leaves only the Ir region which is used for detection. High dynamic ranges of 160 dB are ensured for all UV, Ir and RGB which they are excellent for color sensing. Consequently, combined with the previously proposed RGB sensing, the new RGB+UV+Ir sensor is realized without any filters.

Three-level nanogrooves by vibration-assisted fly-cutting for diffraction regulation and array output.

Integrating geometric and diffractive optics functions is urgently needed to develop compact equipment for integrating diffraction manipulation and arrayed outputs. In this Letter, a superimposed three-level-grooved surface is proposed to manipulate the diffraction of visible light and provide an array output. Structure design, vibration-assisted fly-cutting, finite-difference time-domain calculations, and diffraction tests are conducted to fabricate the three-level grooves and explore the diffraction mechanism. Nanogrooves with a period close to the middle wavelength of the spectrum primarily enhances the diffraction at low diffraction orders and angles because of resonance. Optical tests prove that these superimposed three-level nanogrooves have a large bandwidth when providing the array output and serving to control and transmit diffracted light. They also show stronger performance for manipulating low diffraction orders.

Application of an innovative narrow band vegetation index to corn leaves to explore the characteristics of corn spectra under Cu2+ stress

ABSTRACT In this study, an innovative narrow band vegetation index (INBVI) was proposed to explore the sensitive regions of corn leaves spectra under copper stress. In 2016, the spectra and Cu2+ contents of corn leaves under different copper stress concentrations were measured by designing corn stress experiments with different copper gradients. Firstly, we divided the spectra of corn leaves into 11 subintervals, and chose the spectral reflectance which corresponded to the middle wavelength of each subinterval to build INBVI. Then, the Pearson correlation coefficient (r) and Root Mean Square Error (RMSE) were calculated, and we analysed correlation of the INBVI and Cu2+ contents in corn leaves. What’s more, we compared it with the three conventional vegetation indexes of Water Band Index (WBI), Modified Chlorophyll Absorption Ratio Index (MCARI) and Normalized Difference Water Index (NDWI). Finally, the spectra of corn leaves obtained under the same experimental conditions in other year were used to verify the stability and effectiveness of INBVI. The results showed that the four subintervals of Green peak, Red edge, Near valley and Near peak A were sensitive intervals, because the absolute value of r exceeded .9, and the RMSE values were lower than other subintervals and the three conventional vegetation indexes. We verified the above results and found the sensitive intervals were Green peak, Red edge, Near valley and Near peak A, which were consistent with the sensitive subintervals obtained from the experiment data in 2016, and confirmed the effectiveness and stability of INBVI. The INBVI proposed in this paper can be used as a method to monitor copper pollution in corn leaves, and provide some theoretical support for the research of heavy metal pollution in other crops.

Mepanipyrim induces visual developmental toxicity and vision-guided behavioral alteration in zebrafish larvae

Mepanipyrim, an anilinopyrimidine fungicide, has been extensively used to prevent fungal diseases in fruit culture. Currently, research on mepanipyrim-induced toxicity in organisms is still very scarce, especially visual developmental toxicity. Here, zebrafish larvae were employed to investigate mepanipyrim-induced visual developmental toxicity. Intense light and monochromatic light stimuli-evoked escape experiments were used to investigate vision-guided behaviors. Meanwhile, transcriptomic sequencing and real-time quantitative PCR assays were applied to assess the potential mechanisms of mepanipyrim-induced visual developmental toxicity and vision-guided behavioral alteration. Our results showed that mepanipyrim exposure could induce retinal impairment and vision-guided behavioral alteration in larval zebrafish. In addition, the grk1b gene of the phototransduction signaling pathway was found to be a potential aryl hydrocarbon receptor (AhR)-regulated gene. Mepanipyrim-induced visual developmental toxicity was potentially related to the AhR signaling pathway. Furthermore, mepanipyrim-induced behavioral alteration was guided by the visual function, and the effects of mepanipyrim on long and middle wavelength light-sensitive opsins may be the main cause of vision-guided behavioral alteration. Our results provide insights into understanding the relationship between visual development and vision-guided behaviors induced by mepanipyrim exposure.