Discovery of a body-wide photosensory array that matures in an adult-like animal and mediates eye-brain-independent movement and arousal.

The ability to respond to light has profoundly shaped life. Animals with eyes overwhelmingly rely on their visual circuits for mediating light-induced coordinated movements. Building on previously reported behaviors, we report the discovery of an organized, eye-independent (extraocular), body-wide photosensory framework that allows even a head-removed animal to move like an intact animal. Despite possessing sensitive cerebral eyes and a centralized brain that controls most behaviors, head-removed planarians show acute, coordinated ultraviolet-A (UV-A) aversive phototaxis. We find this eye-brain-independent phototaxis is mediated by two noncanonical rhabdomeric opsins, the first known function for this newly classified opsin-clade. We uncover a unique array of dual-opsin-expressing photoreceptor cells that line the periphery of animal body, are proximal to a body-wide nerve net, and mediate UV-A phototaxis by engaging multiple modes of locomotion. Unlike embryonically developing cerebral eyes that are functional when animals hatch, the body-wide photosensory array matures postembryonically in "adult-like animals." Notably, apart from head-removed phototaxis, the body-wide, extraocular sensory organization also impacts physiology of intact animals. Low-dose UV-A, but not visible light (ocular-stimulus), is able to arouse intact worms that have naturally cycled to an inactive/rest-like state. This wavelength selective, low-light arousal of resting animals is noncanonical-opsin dependent but eye independent. Our discovery of an autonomous, multifunctional, late-maturing, organized body-wide photosensory system establishes a paradigm in sensory biology and evolution of light sensing.

Combined Ionizing Radiation Exposure by Gamma Rays and Carbon-12 Nuclei Increases Neurotrophic Factor Content and Prevents Age-Associated Decreases in the Volume of the Sensorimotor Cortex in Rats.

In orbital and ground-based experiments, it has been demonstrated that ionizing radiation (IR) can stimulate the locomotor and exploratory activity of rodents, but the underlying mechanism of this phenomenon remains undisclosed. Here, we studied the effect of combined IR (0.4 Gy γ-rays and 0.14 Gy carbon-12 nuclei) on the locomotor and exploratory activity of rats, and assessed the sensorimotor cortex volume by magnetic resonance imaging-based morphometry at 1 week and 7 months post-irradiation. The sensorimotor cortex tissues were processed to determine whether the behavioral and morphologic effects were associated with changes in neurotrophin content. The irradiated rats were characterized by increased locomotor and exploratory activity, as well as novelty-seeking behavior, at 3 days post-irradiation. At the same time, only unirradiated rats experienced a significant decrease in the sensorimotor cortex volume at 7 months. While there were no significant differences at 1 week, at 7 months, the irradiated rats were characterized by higher neurotrophin-3 and neurotrophin-4 content in the sensorimotor cortex. Thus, IR prevents the age-associated decrease in the sensorimotor cortex volume, which is associated with neurotrophic and neurogenic changes. Meanwhile, IR-induced increases in locomotor activity may be the cause of the observed changes.

Effects of non-ionizing radio frequency electromagnetic radiation on the development and behavior of early embryos of Danio rerio.

Biological effects of radio frequency electromagnetic radiation (RF-EMR) in the range of 900-1800 MHz emerging from the mobile phone were investigated and were found to influence the locomotor pattern when exposure was initiated from 1 hour post fertilization (hpf) in zebrafish embryos (ZE), Danio rerio. Mobile phones and other wireless devices offer tremendous advantages. However, on the flipside they are leading to an increased electromagnetic energy in the environment, an excess of which could be termed as electromagnetic pollution. Herein, we tried to understand the effects of RF-EMR emerging from the mobile phone, on the development and behavior of ZE, exposed to RF-EMR (specific absorption rate of 1.13 W/kg and 1800 MHz frequency) 1 hr daily, for 5 days. To understand if there could be any developmental stage-specific vulnerability to RF-EMR, the exposure was initiated at three different time points: 1hpf, 6hpf and 24hpf of ZE development. Observations revealed no significant changes in the survival rate, morphology, oxidative stress or cortisol levels. However, statistically significant variations were observed in the batch where exposure started at 1hpf, with respect to locomotion patterns (distance travelled: 659.1 ± 173.1 mm Vs 963.5 ± 200.4 mm), which could be correlated to anxiety-like behavior; along with a corresponding increase in yolk consumption (yolk sac area: 0.251 ± 0.019 mm2 Vs 0.225 ± 0.018 mm2). Therefore, we conclude that RF-EMR exposure influences the organism maximally during the earliest stage of development, and we also believe that an increase in the time of exposure (corresponding to the patterns of current usage of mobile phones) might reveal added afflictions.

Mobile phones and other wireless devices are on a rampant usage worldwide. They work by radiating low energy radiofrequency electromagnetic radiations. An excessive usage of wireless devices is leading to increased presence of these radiations in our surroundings. Since these radiations are not physically sensed by the organisms, its impact stays elusive. Nevertheless, the interaction of these radiations with biological systems may produce some unwarranted effects. When we exposed the ZE to the mobile phone radiation daily 1hr for 5days, our observations revealed that the youngest of the experimental group showed susceptibility. The effect was evident through haphazard movements and stressed behavior. So, it is important to be aware of the potential effects and take necessary precautions by following safety guidelines, especially when the organism is in its early life stage.

Light intensity alters the effects of light-induced circadian disruption on glucose and lipid metabolism in mice.

Circadian disruption induced by rotating light cycles has been linked to metabolic disorders. However, how the interaction of light intensity and light cycle affects metabolism under different diets remains to be explored. Eighty mice were first randomly stratified into the low-fat diet (LFD, n = 40) or high-fat diet (HFD, n = 40) groups. Each group was further randomly subdivided into four groups (n = 8-12 per group) in terms of different light intensities [lower (LI, 78 lx) or higher intensity (HI, 169 lx)] and light cycles [12-h light:12-h dark cycle or circadian-disrupting (CD) light cycle consisting of repeated 6-h light phase advancement]. Body weight was measured weekly. At the end of the 16-wk experiment, mice were euthanized for serum and pathological analysis. Glucose and insulin tolerance tests were performed during the last 2 wk. The CD cycle increased body weight gain, adipocyte area, glucose intolerance, and insulin resistance of LFD as well as HFD mice under HI but not LI condition. Moreover, the serum and hepatic triglyceride levels increased with LFD-HI treatment, regardless of light cycle. In addition, the CD cycle improved lipid and glucose metabolism under HFD-LI condition. In summary, the detrimental effects of the CD cycle on metabolism were alleviated under LI condition, especially in HFD mice. These results indicate that modulating light intensity is a potential strategy to prevent the negative metabolic consequences associated with jet lag or shift work.NEW & NOTEWORTHY Glucose and lipid homeostasis is altered by the CD cycles in a light-intensity-dependent manner. Lower-intensity light reverses the negative metabolic effects of the CD cycles, especially under HFD feeding. The interaction of light intensity and light cycle on metabolism is independent of energy intake and eating pattern. Glucose metabolic disorders caused by rotating light cycles occur along with compensatory ß-cell mass expansion.

Distinct mechanisms of Drosophila CRYPTOCHROME-mediated light-evoked membrane depolarization and in vivo clock resetting.

Drosophila CRYPTOCHROME (dCRY) mediates electrophysiological depolarization and circadian clock resetting in response to blue or ultraviolet (UV) light. These light-evoked biological responses operate at different timescales and possibly through different mechanisms. Whether electron transfer down a conserved chain of tryptophan residues underlies biological responses following dCRY light activation has been controversial. To examine these issues in in vivo and in ex vivo whole-brain preparations, we generated transgenic flies expressing tryptophan mutant dCRYs in the conserved electron transfer chain and then measured neuronal electrophysiological phototransduction and behavioral responses to light. Electrophysiological-evoked potential analysis shows that dCRY mediates UV and blue-light-evoked depolarizations that are long lasting, persisting for nearly a minute. Surprisingly, dCRY appears to mediate red-light-evoked depolarization in wild-type flies, absent in both cry-null flies, and following acute treatment with the flavin-specific inhibitor diphenyleneiodonium in wild-type flies. This suggests a previously unsuspected functional signaling role for a neutral semiquinone flavin state (FADH•) for dCRY. The W420 tryptophan residue located closest to the FAD-dCRY interaction site is critical for blue- and UV-light-evoked electrophysiological responses, while other tryptophan residues within electron transfer distance to W420 do not appear to be required for light-evoked electrophysiological responses. Mutation of the dCRY tryptophan residue W342, more distant from the FAD interaction site, mimics the cry-null behavioral light response to constant light exposure. These data indicate that light-evoked dCRY electrical depolarization and clock resetting are mediated by distinct mechanisms.

High-Dose Irradiation Inhibits Motility and Induces Autophagy in Caenorhabditis elegans.

Radiation damages many cellular components and disrupts cellular functions, and was previously reported to impair locomotion in the model organism Caenorhabditis elegans. However, the response to even higher doses is not clear. First, to investigate the effects of high-dose radiation on the locomotion of C. elegans, we investigated the dose range that reduces whole-body locomotion or leads to death. Irradiation was performed in the range of 0-6 kGy. In the crawling analysis, motility decreased after irradiation in a dose-dependent manner. Exposure to 6 kGy of radiation affected crawling on agar immediately and caused the complete loss of motility. Both γ-rays and carbon-ion beams significantly reduced crawling motility at 3 kGy. Next, swimming in buffer was measured as a motility index to assess the response over time after irradiation and motility similarly decreased. However, swimming partially recovered 6 h after irradiation with 3 kGy of γ-rays. To examine the possibility of a recovery mechanism, in situ GFP reporter assay of the autophagy-related gene lgg-1 was performed. The fluorescence intensity was stronger in the anterior half of the body 7 h after irradiation with 3 kGy of γ-rays. GFP::LGG-1 induction was observed in the pharynx, neurons along the body, and the intestine. Furthermore, worms were exposed to region-specific radiation with carbon-ion microbeams and the trajectory of crawling was measured by image processing. Motility was lower after anterior-half body irradiation than after posterior-half body irradiation. This further supported that the anterior half of the body is important in the locomotory response to radiation.

Does a Red House Affect Rhythms in Mice with a Corrupted Circadian System?

The circadian rhythms of body functions in mammals are controlled by the circadian system. The suprachiasmatic nucleus (SCN) in the hypothalamus orchestrates subordinate oscillators. Time information is conveyed from the retina to the SCN to coordinate an organism's physiology and behavior with the light/dark cycle. At the cellular level, molecular clockwork composed of interlocked transcriptional/translational feedback loops of clock genes drives rhythmic gene expression. Mice with targeted deletion of the essential clock gene Bmal1 (Bmal1-/-) have an impaired light input pathway into the circadian system and show a loss of circadian rhythms. The red house (RH) is an animal welfare measure widely used for rodents as a hiding place. Red plastic provides light at a low irradiance and long wavelength-conditions which affect the circadian system. It is not known yet whether the RH affects rhythmic behavior in mice with a corrupted circadian system. Here, we analyzed whether the RH affects spontaneous locomotor activity in Bmal1-/- mice under standard laboratory light conditions. In addition, mPER1- and p-ERK-immunoreactions, as markers for rhythmic SCN neuronal activity, and day/night plasma corticosterone levels were evaluated. Our findings indicate that application of the RH to Bmal1-/- abolishes rhythmic locomotor behavior and dampens rhythmic SCN neuronal activity. However, RH had no effect on the day/night difference in corticosterone levels.

Decoupling behavioral and transcriptional responses to color in an eyeless cnidarian.

BACKGROUND: Animals have specific molecular, physiological, and behavioral responses to light that are influenced by wavelength and intensity. Predictable environmental changes - predominantly solar and lunar cycles - drive endogenous daily oscillations by setting internal pacemakers, otherwise known as the circadian clock. Cnidarians have been a focal group to discern the evolution of light responsiveness due to their phylogenetic position as a sister phylum to bilaterians and broad range of light-responsive behaviors and physiology. Marine species that occupy a range of depths will experience different ranges of wavelengths and light intensities, which may result in variable phenotypic responses. Here, we utilize the eyeless sea anemone Nematostella vectensis, an estuarine anemone that typically resides in shallow water habitats, to compare behavioral and molecular responses when exposed to different light conditions. RESULTS: Quantitative measures of locomotion clearly showed that this species responds to light in the blue and green spectral range with a circadian activity profile, in contrast to a circatidal activity profile in the red spectral range and in constant darkness. Differences in average day/night locomotion was significant in each condition, with overall peak activity during the dark period. Comparative analyses of 96 transcriptomes from individuals sampled every 4 h in each lighting treatment revealed complex differences in gene expression between colors, including in many of the genes likely involved in the cnidarian circadian clock. Transcriptional profiling showed the majority of genes are differentially expressed when comparing mid-day with mid-night, and mostly in red light. Gene expression profiles were largely unique in each color, although animals in blue and green were overall more similar to each other than to red light. CONCLUSIONS: Together, these analyses support the hypothesis that cnidarians are sensitive to red light, and this perception results in a rich transcriptional and divergent behavioral response. Future work determining the specific molecular mechanisms driving the circadian and potential circatidal rhythms measured here would be impactful to connect gene expression variation with behavioral variation in this eyeless species.

Egocentric and allocentric representations in auditory cortex.

A key function of the brain is to provide a stable representation of an object's location in the world. In hearing, sound azimuth and elevation are encoded by neurons throughout the auditory system, and auditory cortex is necessary for sound localization. However, the coordinate frame in which neurons represent sound space remains undefined: classical spatial receptive fields in head-fixed subjects can be explained either by sensitivity to sound source location relative to the head (egocentric) or relative to the world (allocentric encoding). This coordinate frame ambiguity can be resolved by studying freely moving subjects; here we recorded spatial receptive fields in the auditory cortex of freely moving ferrets. We found that most spatially tuned neurons represented sound source location relative to the head across changes in head position and direction. In addition, we also recorded a small number of neurons in which sound location was represented in a world-centered coordinate frame. We used measurements of spatial tuning across changes in head position and direction to explore the influence of sound source distance and speed of head movement on auditory cortical activity and spatial tuning. Modulation depth of spatial tuning increased with distance for egocentric but not allocentric units, whereas, for both populations, modulation was stronger at faster movement speeds. Our findings suggest that early auditory cortex primarily represents sound source location relative to ourselves but that a minority of cells can represent sound location in the world independent of our own position.

The possible neurobehavioral protective effects of natural antioxidant against phototoxicity attenuation of antimicrobial quinolone group in rats.

The fluoroquinolones absorb light in the 320 to 330 nm ultraviolet A (UV-A) wavelength and produce reactive oxygen species (ROS) such as superoxide anion, hydroxyl radical, and hydrogen peroxide; thus, the photodynamic generation of ROS may be the basis of phototoxicity of quinolones in human beings and animals. This study aimed to evaluate the damaging effects of UV-A radiation at different periods of exposure on rats' brains administered with ciprofloxacin. Ciprofloxacin administration in UV-A exposed animals exaggerated the brain-oxidative stress biomarkers and decreased the locomotor activity. Exposure of rats to UV-A for 60 minutes induced a significant increase of malondialdehyde (MDA), myeloperoxidase (MPO), and a decrease in the values of superoxide dismutase (SOD), glutathione (GSH) compared to a normal one; these changes were UV-A exposure time-dependent. However, the administration of vitamin C to the UV-60-treated group decreased the values of MDA, MPO, and shifted the values of SOD, GSH toward the normal values. Vitamin C, probably due to its strong antioxidant properties, could improve and partially counteract the toxic effect of UV-A on oxidative stress parameters and prevent the damage in rat's brain tissues.

Photobiomodulation therapy and NMES improve muscle strength and jumping performance in young volleyball athletes: a randomized controlled trial study in Brazil.

The purpose of this study was to investigate the effectiveness of adding photobiomodulation therapy and neuromuscular electrical stimulation (NMES) to volleyball athletes' training, focusing on muscle strength and jumping skills. Thirty-six athletes were randomly placed into three groups: control, photobiomodulation therapy, and NMES. The athletes trained to improve their muscle strength and jumping skills. The athletes in the photobiomodulation therapy group were submitted to photobiomodulation therapy (850 nm, continuous, energy density 0.8 J/cm2, radiant energy per point 6 J, total radiant energy 36 J) before undergoing strength and plyometric training. The NMES group additionally underwent NMES-based quadriceps femoris muscle strength training (base frequency 1 kHz, frequency modulation 70 Hz, intensity maximum tolerable). The variables analyzed were muscle strength, jumping ability, global impression, and jump frequency; they were measured at baseline and during follow-ups at 6 and 8 weeks. The statistical analysis was conducted on an intention-to-treat basis. The between-group differences and their respective 95% CIs were calculated using linear mixed models by using group, time, and group-versus-time interaction terms. Dominant lower limb strength improved the most in the NMES group compared to the control group (mean difference = 1.4, 95% CI = .5 to 2.4). Non-dominant lower limb strength increased in both the photobiomodulation therapy group (mean difference = 1.1, 95% CI = .3 to 2) and the NMES group (mean difference = 1.9, 95% CI = 1.1 to 2.8) compared to the control group, but the NMES group improved more than the photobiomodulation therapy group (mean difference = 0.8, 95% CI = 0.1 to 1.7). The NMES group had the greatest improvement in global perceived effect scale compared to the control group (mean difference = 1.1, 95% CI = 1 to 2.2). Dominant lower limb strength improved in the NMES group compared to the control group. Non-dominant lower limb strength increased in both the photobiomodulation therapy group and the NMES group compared to the control group, but the NMES group improved significantly more than the photobiomodulation therapy group; the NMES group also improved in the global perceived effect scale compared to the control group. This study found that, for volleyball athletes, photobiomodulation therapy and NMES both promoted benefits in terms of muscle-strength gain. In addition, these benefits were maintained for 2 weeks even after training was interrupted. Dominant lower limb strength improved in the NMES group compared to the control group. Non-dominant lower limb strength increased in both the photobiomodulation therapy group and the NMES group compared to the control group, but the NMES group improved significantly more than the photobiomodulation therapy group; the NMES group also improved in global impression of jumps compared to the control group.

A Novel Function of the Lysophosphatidic Acid Receptor 3 (LPAR3) Gene in Zebrafish on Modulating Anxiety, Circadian Rhythm Locomotor Activity, and Short-Term Memory.

Lysophosphatidic acid (LPA) is a small lysophospholipid molecule that activates multiple cellular functions through pathways with G-protein-coupled receptors. So far, six LPA receptors (LPAR1 to LPAR6) have been discovered and each one of them can connect to the downstream cell message-transmitting network. A previous study demonstrated that LPA receptors found in blood-producing stem cells can enhance erythropoietic processes through the activation of LPAR3. In the current study, newly discovered functions of LPAR3 were identified through extensive behavioral tests in lpar3 knockout (KO) zebrafish. It was found that the adult lpar3 KO zebrafish display an abnormal movement orientation and altered exploratory behavior compared to that of the control group in the three-dimensional locomotor and novel tank tests, respectively. Furthermore, consistent with those results, in the circadian rhythm locomotor activity test, the lpar3 KO zebrafish showed a lower level of angular velocity and average speed during the light cycles, indicating an hyperactivity-like behavior. In addition, the mutant fish also exhibited considerably higher locomotor activity during the dark cycle. Supporting those findings, this phenomenon was also displayed in the lpar3 KO zebrafish larvae. Furthermore, several important behavior alterations were also observed in the adult lpar3 KO fish, including a lower degree of aggression, less interest in conspecific social interaction, and looser shoal formation. However, there was no significant difference regarding the predator avoidance behavior between the mutant and the control fish. In addition, lpar3 KO zebrafish displayed memory deficiency in the passive avoidance test. These in vivo results support for the first time that the lpar3 gene plays a novel role in modulating behaviors of anxiety, aggression, social interaction, circadian rhythm locomotor activity, and memory retention in zebrafish.

Effects of reduced natural background radiation on Drosophila melanogaster growth and development as revealed by the FLYINGLOW program.

Natural background radiation of Earth and cosmic rays played a relevant role during the evolution of living organisms. However, how chronic low doses of radiation can affect biological processes is still unclear. Previous data have indicated that cells grown at the Gran Sasso Underground Laboratory (LNGS, L'Aquila) of National Institute of Nuclear Physics (INFN) of Italy, where the dose rate of cosmic rays and neutrons is significantly reduced with respect to the external environment, elicited an impaired response against endogenous damage as compared to cells grown outside LNGS. This suggests that environmental radiation contributes to the development of defense mechanisms at cellular level. To further understand how environmental radiation affects metabolism of living organisms, we have recently launched the FLYINGLOW program that aims at exploiting Drosophila melanogaster as a model for evaluating the effects of low doses/dose rates of radiation at the organismal level. Here, we will present a comparative data set on lifespan, motility and fertility from different Drosophila strains grown in parallel at LNGS and in a reference laboratory at the University of L'Aquila. Our data suggest the reduced radiation environment can influence Drosophila development and, depending on the genetic background, may affect viability for several generations even when flies are moved back to normal background radiation. As flies are considered a valuable model for human biology, our results might shed some light on understanding the effect of low dose radiation also in humans.

The circadian activity rhythm is reset by nanowatt pulses of ultraviolet light.

The circadian pacemaker synchronizes to the Earth's rotation by tracking step-by-step changes in illumination that occur as the sun passes the horizon. While twilight progressions of irradiance and colour are considered important stimuli in this process, comparably less thought has been given to the possibility that ultraviolet A (UVA) radiation might actually play a more formative role given its evolutionary significance in shaping 24 h timekeeping. Here, we show that Drosophila activity rhythms can be phase-shifted by UVA light at an energy range seated well below that of the visible spectrum. Because the energy threshold for this resetting matches the incident amount of UVA on the human retina at twilight, our results suggest that UVA light has the potential to function as a similar time cue in people.

Genetic analysis of circadian responses to low frequency electromagnetic fields in Drosophila melanogaster.

The blue-light sensitive photoreceptor cryptochrome (CRY) may act as a magneto-receptor through formation of radical pairs involving a triad of tryptophans. Previous genetic analyses of behavioral responses of Drosophila to electromagnetic fields using conditioning, circadian and geotaxis assays have lent some support to the radical pair model (RPM). Here, we describe a new method that generates consistent and reliable circadian responses to electromagnetic fields that differ substantially from those already reported. We used the Schuderer apparatus to isolate Drosophila from local environmental variables, and observe extremely low frequency (3 to 50 Hz) field-induced changes in two locomotor phenotypes, circadian period and activity levels. These field-induced phenotypes are CRY- and blue-light dependent, and are correlated with enhanced CRY stability. Mutational analysis of the terminal tryptophan of the triad hypothesised to be indispensable to the electron transfer required by the RPM reveals that this residue is not necessary for field responses. We observe that deletion of the CRY C-terminus dramatically attenuates the EMF-induced period changes, whereas the N-terminus underlies the hyperactivity. Most strikingly, an isolated CRY C-terminus that does not encode the Tryptophan triad nor the FAD binding domain is nevertheless able to mediate a modest EMF-induced period change. Finally, we observe that hCRY2, but not hCRY1, transformants can detect EMFs, suggesting that hCRY2 is blue light-responsive. In contrast, when we examined circadian molecular cycles in wild-type mouse suprachiasmatic nuclei slices under blue light, there was no field effect. Our results are therefore not consistent with the classical Trp triad-mediated RPM and suggest that CRYs act as blue-light/EMF sensors depending on trans-acting factors that are present in particular cellular environments.

Red LED photobiomodulation reduces pain hypersensitivity and improves sensorimotor function following mild T10 hemicontusion spinal cord injury.

BACKGROUND: The development of hypersensitivity following spinal cord injury can result in incurable persistent neuropathic pain. Our objective was to examine the effect of red light therapy on the development of hypersensitivity and sensorimotor function, as well as on microglia/macrophage subpopulations following spinal cord injury. METHODS: Wistar rats were treated (or sham treated) daily for 30 min with an LED red (670 nm) light source (35 mW/cm(2)), transcutaneously applied to the dorsal surface, following a mild T10 hemicontusion injury (or sham injury). The development of hypersensitivity was assessed and sensorimotor function established using locomotor recovery and electrophysiology of dorsal column pathways. Immunohistochemistry and TUNEL were performed to examine cellular changes in the spinal cord. RESULTS: We demonstrate that red light penetrates through the entire rat spinal cord and significantly reduces signs of hypersensitivity following a mild T10 hemicontusion spinal cord injury. This is accompanied with improved dorsal column pathway functional integrity and locomotor recovery. The functional improvements were preceded by a significant reduction of dying (TUNEL(+)) cells and activated microglia/macrophages (ED1(+)) in the spinal cord. The remaining activated microglia/macrophages were predominantly of the anti-inflammatory/wound-healing subpopulation (Arginase1(+)ED1(+)) which were expressed early, and up to sevenfold greater than that found in sham-treated animals. CONCLUSIONS: These findings demonstrate that a simple yet inexpensive treatment regime of red light reduces the development of hypersensitivity along with sensorimotor improvements following spinal cord injury and may therefore offer new hope for a currently treatment-resistant pain condition.

Light level impacts locomotor biomechanics in a secondarily diurnal gecko, Rhoptropus afer.

Locomotion through complex habitats relies on the continuous feedback from a number of sensory systems, including vision. Animals face a visual trade-off between acuity and light sensitivity that depends on light levels, which will dramatically impact the ability to process information and move quickly through a habitat, making ambient illumination an incredibly important ecological factor. Despite this, there is a paucity of data examining ambient light in the context of locomotor dynamics. There have been several independent transitions from the nocturnal ancestor to a diurnal activity pattern among geckos. We examined how ambient light level impacted the locomotor performance and high-speed three-dimensional kinematics of a secondarily diurnal, and cursorial, gecko (Rhoptropus afer) from Namibia. This species is active under foggy and sunny conditions, indicating that a range of ambient light conditions is experienced naturally. Locomotor speed was lowest in the 'no-light' condition compared with all other light intensities, occurring via a combination of shorter stride length and lower stride frequency. Additionally, the centre of mass was significantly lower, and the geckos were more sprawled, in the no-light condition relative to all of the higher light intensities. Locomotor behaviour is clearly sub-optimal under lower light conditions, suggesting that ecological conditions, such as very dense fog, might preclude the ability to run quickly during predator-prey interactions. The impact of ambient light on fitness should be explored further, especially in those groups that exhibit multiple transitions between diel activity patterns.

Synchronization to light and mealtime of the circadian rhythms of self-feeding behavior and locomotor activity of white shrimps (Litopenaeus vannamei).

The role of light and feeding cycles in synchronizing self-feeding and locomotor activity rhythms was studied in white shrimps using a new self-feeding system activated by photocell trigger. In experiment 1, shrimps maintained under a 12:12h light/dark (LD) photoperiod were allowed to self-feed using feeders connected to a photoelectric cell, while locomotor activity was recorded with a second photocell. On day 30, animals were subjected to constant darkness (DD) for 12days to check the existence of endogenous circadian rhythms. In the experiment 2, shrimps were exposed to both a 12:12h LD photoperiod and a fixed meal schedule in the middle of the dark period (MD, 01:00h). On day 20, shrimps were exposed to DD conditions and the same fixed feeding. On day 30, they were maintained under DD and fasted for 7days. The results revealed that under LD, shrimps showed a clear nocturnal feeding pattern and locomotor activity (81.9% and 67.7% of total daily food-demands and locomotor activity, respectively, at nighttime). Both feeding and locomotor rhythms were endogenously driven and persisted under DD with an average period length (τ) close to 24h (circadian) (τ=24.18±0.13 and 23.87±0.14h for locomotor and feeding, respectively). Moreover, Shrimp showed a daily food intake under LD condition (1.1±0.2gday(-1) in the night phase vs. 0.2±0.1gday(-1) in the light phase). Our findings might be relevant for some important shrimp aquaculture aspects, such as developing suitable feeding management on shrimp farms.

Feverlike Temperature is a Virulence Regulatory Cue Controlling the Motility and Host Cell Entry of Typhoidal Salmonella.

Human infection with typhoidal Salmonella serovars causes a febrile systemic disease, termed enteric fever. Here we establish that in response to a temperature equivalent to fever (39 °C-42 °C) Salmonella enterica serovars Typhi, Paratyphi A, and Sendai significantly attenuate their motility, epithelial cell invasion, and uptake by macrophages. Under these feverlike conditions, the residual epithelial cell invasion of S. Paratyphi A occurs in a type III secretion system (T3SS) 1-independent manner and results in restrained disruption of epithelium integrity. The impaired motility and invasion are associated with down-regulation of T3SS-1 genes and class II and III (but not I) of the flagella-chemotaxis regulon. In contrast, we demonstrate up-regulation of particular Salmonella pathogenicity island 2 genes (especially spiC) and increased intraepithelial growth in a T3SS-2-dependent manner. These results indicate that elevated physiological temperature is a novel cue controlling virulence phenotypes in typhoidal serovars, which is likely to play a role in the distinct clinical manifestations elicited by typhoidal and nontyphoidal salmonellae.

The archaellum: a rotating type IV pilus.

Microbes have evolved sophisticated mechanisms of motility allowing them to respond to changing environmental conditions. While this cellular process is well characterized in bacteria, the mode and mechanisms of motility are poorly understood in archaea. This study examines the motility of individual cells of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. Specifically, we investigated motility of cells producing exclusively the archaeal swimming organelle, the archaellum. Archaella are structurally and in sequence similar to bacterial type IV pili involved in surface motility via pilus extension-retraction cycles and not to rotating bacterial flagella. Unexpectedly, our studies reveal a novel type of behaviour for type IV pilus like structures: archaella rotate and their rotation drives swimming motility. Moreover, we demonstrate that temperature has a direct effect on rotation velocity explaining temperature-dependent swimming velocity.