Assessment of negative phototaxis in long-term fasted Glyptocidaris crenularis:a new insight into measuring stress responses of sea urchins in aquaculture

A cost-effective method was designed to measure the behavioral response of negative phototaxis to high-intensity illumination in the sea urchin Glyptocidaris crenularis. Ninety sea urchins were randomly and equally divided into two aquaculture environment groups： a fasted group, which was starved during the experiment, and a fed group. After 10 months, the total mortality of each group was recorded. Then, 15 sea urchins were randomly selected from each group and behavioral responses to high-intensity illumination were investigated for each sea urchin. After the behavioral experiment, body measurements of the trial sea urchins were taken. The results reveal that food deprivation significantly affected test diameter （P〈0.01）, body weight （P〈0.01）, gonad weight （P〈0.0I）, and gut weight （P〈0.01）. Furthermore, food deprivation also affected negative phototaxis behaviors of time to rapid spine movement （P〈0.01）, time to the 1 cm position （P〈0.05）, and walking distance in 300 s （P〈0.01）, but not time to body reaction （P〉0.05）. The mortality rates of fasted and fed urchins were 6.7% and 0%, respectively. The present study provides evidence that food deprivation has a significant effect on phenotypic traits and behavioral responses to high-intensity illumination in the sea urchin G. crenularis. With this method, environmental stressors can be easily detected by measuring proper optional indicators. This study provides a new insight into measuring stress responses of sea urchins in aquaculture. However, further studies should be carried out to understand more environmental factors and to compare this potential behavioral method with immune, physiological, and epidemiological approaches.

Synaptic a-Si:H/a-Ga_(2)O_(3) phototransistor inspired by the phototaxis behavior of organisms with all-optical and all-electrical stimulation modes

To improve neuromorphic computing performance,neuromorphic system components should mimic the behaviors of organic systems.In this study,a synaptic a-Si:H/a-Ga_(2)O_(3)phototransistor featuring all-optical and-electrical emulation is fabricated in a manner advantageous for complementary metal-oxide-semiconductor process integration.The phototransistor exhibits excitatory and inhibitory synaptic behaviors under stimulation by both optical and electrical signals.It mimics several essential synaptic functions,including excitatory postsynaptic current,inhibitory postsynaptic current,short-term memory,long-term memory,pairedpulse facilitation,and spike-timing-dependent plasticity.The optical and electrical modulation mechanisms are confirmed to arise from the a-Si:H/a-Ga_(2)O_(3) heterojunction structure and interface effects,and the device is shown to operate at low power in both optical and electrical modes.The all-optical weight modulation function is applied to the wavelength-differential behavior response of zebrafish,successfully mimicking the color perception process of the organism.Finally,to verify the translation of the optoelectrical-derived synaptic behaviors of the phototransistor into artificial neuromorphic computation,handwritten digit image recognition of the Modified National Institute of Standards and Technology dataset is performed by a convolutional neural network,with a demonstrated average learning accuracy of 98.46%.These findings verify the applicability of the synaptic a-Si:H/a-Ga_(2)O_(3) phototransistor in neuromorphic computing.

Enhancement of the geomagnetic field reduces the phototaxis of rice brown planthopper Nilaparvata lugens associated with frataxin down-regulation

The geomagnetic field(GMF)is an environmental cue that provides directional information for animals.The intensity of GMF is varied over space and time.Variations in the GMF intensity afect the navigation of animals and their physiology.In this study,the phototaxis of the migratory insect rice planthopper Nilaparvata lugens(N.lugens)and frataxin in N.lugens(NI-fh),which is a mitochondrial protein required for cellular iron homeostasis and iron-sulfur cluster assembly,were investigated by using different intensities of magnetic field.From the results,individuals of N.lugens showed decreased phototaxis when reared and tested in a behavioral arena under a strong magnetic field.Besides the reduction in performance,an accompanying ffect of the strong magnetic field condition was a reduced level of Nl-fh-messenger RNA,and a NI-fh knockdown indeed impaired the phototactic behavior in a tested sample of insects.This leads to the conclusion that the expression of frataxin is dependent on the strength of the surrounding magnetic field and that functional frataxin facilitates phototactic behavior in N.lugens.

Photobehaviors ofthe calanoid copepod Calanus sinicus from the Yellow Sea to visible and UV-B radiation as a function of wavelength and intensity

The effects of wavelength-specific visible light, white light, and ultraviolet-B (UV-B, 280- 315 nm) on selected behaviors, grazing rate, spawning rate, and hatching rate of the marine copepod Calanus sinicus collected from the Yellow Sea were studied. Calanus sinicus placed in a partitioned experimental system responded positively phototaxis to blue-cyan and yellow light but negatively to orange light and UVB. No obvious dodge activity was found among C. sinicus irradiated with <0.005 mW/cm^2 UV-B. Under 0.20, 0.30 and 0.50 mW/cm^2 UV-B radiation, the lethal half times of individuals were 30.47, 2.86, and 1.96 h, respectively. Grazing of C. sinicus was restrained at >0.10 mW/cm^2 UV-B, whereas yellow-red light stimulated grazing. Egg production rate was highest at a white-light intensity of 1.58 mW/cm^2, with an average rate of 10.04 eggs/(female·d). These results are consistent with the observed phenomenon that C. sinicus in the Yellow Sea mostly spawn near dawn. Our results indicate that light intensity and spectrum are important factors affecting the diel vertical migration of C. sinicus under natural conditions in the Yellow Sea.

Correlation between photoreceptor injury-regeneration and behavior in a zebrafish model

Direct exposure to intensive visible light can lead to solar retinopathy, including macular injury. The signs and symptoms include central scotoma, metamorphopsia, and decreased vision. However, there have been few studies examining retinal injury due to intensive light stimulation at the cellular level. Neural network arrangements and gene expression patterns in zebrafish photoreceptors are similar to those observed in humans, and photoreceptor injury in zebrafish can induce stem cell-based cellular regeneration. Therefore, the zebrafish retina is considered a useful model for studying photoreceptor injury in humans. In the current study, the central retinal photoreceptors of zebrafish were selectively ablated by stimulation with high-intensity light. Retinal injury, cell proliferation and regeneration of cones and rods were assessed at 1, 3 and 7 days post lesion with immunohistochemistry and in situ hybridization. Additionally, a light/dark box test was used to assess zebrafish behavior. The results revealed that photoreceptors were regenerated by 7 days after the light-induced injury. However, the regenerated cells showed a disrupted arrangement at the lesion site. During the injury-regeneration process, the zebrafish exhibited reduced locomotor capacity, weakened phototaxis and increased movement angular velocity. These behaviors matched the morphological changes of retinal injury and regeneration in a number of ways. This study demonstrates that the zebrafish retina has a robust capacity for regeneration. Visual impairment and stress responses following high-intensity light stimulation appear to contribute to the alteration of behaviors.

Phototactic Poly(N-isopropyl acrylamide)Microgels with Photoresponsive Property

Smart functional microgels hold great potential in a variety of applications,especially in drug transportation.However,current drug carriers based on physiological internal stimuli cannot efficiently orientate to designated locations.Therefore,it is necessary to introduce the self-propelled particles to the drug release of the microgels.In order to study self-propulsion of microgels induced by light,it is also a challenge to prepare micronsized microgels so that they can be observed directly under optical microscopes.In this work,phototactic microgels with photoresponsive properties are prepared.The microgel particles can be observed by confocal laser scanning microscopy.The photoresponsive properties of microgels are fully investigated by various instruments.Light can also regulate the state of the microgel solution,making it switch between turbidity and clarity.The phototaxis of particles irradiated by UV light was studied,which may be used for microgels enrichment and drug transportation and release.

Similarities and differences in the peering-jump behavior of three grasshopper species （Orthoptera： Caelifera）

The peering-jump behavior was studied for the common field grasshopper Chorthippus brunneus, the meadow grasshopper C. parallelus and the alpine grasshopper Miramella alpina （Orthoptera, Caelifera）. It was found that immediately before jumping M. alpina executes primarily unilateral object-related peering movements, with approximately twice the amplitude and velocity of the predominantly bilateral object-related peering movements of the other two species. Whereas M. alpina almost always jumped toward the black stripes in the experimental arena, the other species jumped toward both the black stripes and the white spaces between them. All three species preferred the same pattern of black stripes, which permitted them to view one black stripe frontally, with an additional black stripe to the left and right, in the lateral visual field. The similarities and differences in the peering-jump behavior of the three grasshopper species is discussed with regard to visual perception （parallax cues） and environmental adaptation.