Rodents are integral components of ecosystems as they provide several important ecosystem services. Despite their importance as prey, pollinators and seed distributors, African rodents are largely ...understudied. The effect of anthropogenic changes such as artificial light at night extends past urban areas to peri-urban and rural habitats, and can have profound effects on entire ecosystems. We investigated the effect of dim light at night (dLAN) on the locomotor activity rhythms of the African pygmy mouse (
). Pygmy mice showed a dramatic, intensity-dependent reduction in their locomotor activity when subjected to dLAN, which was accompanied by a delay in the activity onset. We also considered masking responses with a dark pulse (DP) during the day and a light pulse at night. All animals became inactive in response to a light pulse during the night, whereas approximately half of the animals showed activity during a DP in the day. Our results suggest that the African pygmy mouse is highly sensitive to light and that their activity is strongly masked by light. In their natural environment, vegetation could shield pygmy mice against high light levels; however, other anthropogenic disturbances can alter the behaviour of these animals and could affect their survival.
•LAN caused the body fattening, weight gain and hepatic lipid accumulation.•LAN altered gut microbiota with an abundance of the pathogenic Proteobacteria.•Lactobacillus decline was correlated with ...negative effects on host physiology.•LGG supplement ameliorated negative effects on the fat accumulation and weight gain.
The gastrointestinal tract (GIT) hosts a large number of diverse microorganisms, with mutualistic interactions with the host. Here, in two separate experiments, we investigated whether light at night (LAN) would affect GIT microbiota and, in turn, the host physiology in diurnal zebra finches (Taeniopygia guttata). Experiment I assessed the effects of no-night (LL) and dimly illuminated night (dim light at night, dLAN) on fecal microbiota diversity and host physiology of birds born and raised under 12 h photoperiod (LD; 12 h light: 12 h darkness). Under LL and dLAN, compared to LD, we found a significant increase in the body mass, subcutaneous fat deposition and hepatic accumulation of lipids. Although we found no difference in total 24 h food consumption, LL/ dLAN birds ate also at night, suggesting LAN-induced alteration in daily feeding times. Concurrently, there were marked differences in amplicon sequence and bacterial species richness between LD and LAN, with notable decline in Lactobacillus richness in birds under LL and dLAN. We attributed declined Lactobacillus population as causal (at least partially) to negative effects on the host metabolism. Therefore, in experiment II with similar protocol, birds under LL and dLAN were fed on diet with or without Lactobacillus rhamnosus GG (LGG) supplement. Clearly, LGG supplement ameliorated LL- and dLAN-induced negative effects in zebra finches. These results demonstrate adverse effects of unnatural lighting on GIT bacterial diversity and host physiology, and suggest the role of GIT microbiota in the maintenance of metabolic homeostasis in response to LAN environment in diurnal animals.
Artificial light at night induces circadian disruptions and causes cognitive impairment and mood disorders; yet very little is known about the neural and molecular correlates of these effects in ...diurnal animals. We manipulated the night environment and examined cellular and molecular changes in hippocampus, the brain region involved in cognition and mood, of Indian house crows (Corvus splendens) exposed to 12 hr light (150 lux): 12 hr darkness (0 lux). Diurnal corvids are an ideal model species with cognitive abilities at par with mammals. Dim light (6 lux) at night (dLAN) altered daily activity:rest pattern, reduced sleep, and induced depressive‐like responses (decreased eating and self‐grooming, self‐mutilation, and reduced novel object exploration); return to an absolute dark night reversed these negative effects. dLAN suppressed nocturnal melatonin levels; however, diurnal corticosterone levels were unaffected. Concomitant reduction of immunoreactivity for DCX and BDNF suggested dLAN‐induced suppression of hippocampal neurogenesis and compromised neuronal health. dLAN also negatively influenced hippocampal expression of genes associated with depressive‐like responses (bdnf, il‐1β, tnfr1, nr4a2), but not of those associated with neuronal plasticity (egr1, creb, syngap, syn2, grin2a, grin2b), cellular oxidative stress (gst, sod3, cat1) and neuronal death (caspase2, caspase3, foxo3). Furthermore, we envisaged the role of BDNF and showed epigenetic modification of bdnf gene by decreased histone H3 acetylation and increased hdac4 expression under dLAN. These results demonstrate transcriptional and epigenetic bases of dLAN‐induced negative effects in diurnal crows, and provide insights into the risks of exposure to illuminated nights to animals including humans in an urban setting.
Artificial light at night induces cognitive impairment and mood disorders. We manipulated the night environment and examined cellular and molecular changes in the hippocampus of Indian house crows exposed to 12 hr light (150 lux): 12 hr darkness (0 or 6 lux). Our results demonstrate dLAN‐induced negative effects on BDNF expression and hippocampal neurogenesis in diurnal crows, and suggest an epigenetic modification of bdnf gene by increased hdac4 expression and decreased histone H3 acetylation.
Display omitted
•We studied how artificial light affects immature firefly development and dispersal.•In general, firefly eggs, larvae and pupae were not affected by dim light at night.•However, ...early-instar Photuris larvae gained body mass more quickly when lit.•Late-instar Photuris larvae burrow down to escape light instead of dispersing away.•This escape behavior may have downstream consequences for the fitness of adults.
Holometabolous insects exhibit complex life cycles in which both morphology and ecological niche change dramatically during development. In the larval stage, many insects have soft, slow-moving bodies and poor vision, limiting their ability to respond to environmental threats. Artificial light at night (ALAN) is an environmental perturbation known to severely impact the fitness of adult insects by disrupting both temporal and spatial orientation. The impact of ALAN on earlier life stages, however, is largely unknown. We conducted a series of laboratory experiments to investigate how two distinct forms of ALAN affect the development and movement of immature Photuris sp. and Photinus obscurellus fireflies. Although long-term exposure to dim light at night (dLAN), akin to urban skyglow, did not impact overall survivorship or duration of egg, larval, and pupal stages in either species, it did accelerate weight gain in early-instar Photuris larvae. Late-instar Photuris exposed to point sources of ALAN at the start of their nightly foraging period were also significantly more likely to burrow beneath the soil surface, rather than disperse across it. ALAN may therefore impede dispersal of firefly larvae away from illuminated areas, which could have downstream consequences for the reproductive fitness of adults.
The accumulation and aggregation of phosphorylated tau proteins in the brain are the hallmarks for the onset of Alzheimer's disease (AD). In addition, disruptions in circadian rhythms (CRs) with ...altered sleep-wake cycles, dysregulation of locomotion, and increased memory defects have been reported in patients with AD. Drosophila flies that have an overexpression of human tau protein in neurons exhibit most of the symptoms of human patients with AD, including locomotion defects and neurodegeneration. Using the fly model for tauopathy/AD, we investigated the effects of an exposure to dim light at night on AD symptoms. We used a light intensity of 10 lux, which is considered the lower limit of light pollution in many countries. After the tauopathy flies were exposed to the dim light at night for 3 days, the flies showed disrupted CRs, altered sleep-wake cycles due to increased pTau proteins and neurodegeneration, in the brains of the AD flies. The results indicate that the nighttime exposure of tauopathy/AD model Drosophila flies to dim light disrupted CR and sleep-wake behavior and promoted neurodegeneration.
•Dim light disturbs circadian rhythm and sleep behaviors.•Internal clock is maintained in Drosophila model of tauopathy Alzheimer's disease.•Short-term disturbance of circadian rhythm by dim light increases formation of phosphorylated Tau in AD model flies.•Dim light exposure at night promotes neurodegeneration in AD model flies.
•Dim-light-at-night (DLAN) disrupts sleep and circadian rhythms in mice.•Sleep features after chronic DLAN converge to an aged sleep phenotype.•Young DLAN mice are mostly affected with a general ...sleep EEG power attenuation.•Slow-wave-activity in NREMs is differentially affected in young and aged DLAN mice.•Irrespective of the mouse age, chronic DLAN impacts sleep and general health.
Dim-light-at-night (DLAN) exposure is associated with health problems, such as metabolic disruptions, immunological modulations, oxidative stress, sleep problems, and altered circadian timing. Neurophysiological parameters, including sleep patterns, are altered in the course of aging in a similar way. Here, we investigated the effect of chronic (three months) DLAN exposure (12 L:12 Dim-light, 75:5 lux) on sleep and the sleep electroencephalogram (EEG), and rest-activity behavior in young (6-month-old, n = 9) and aged (18- n = 8, 24-month-old, n = 6) C57BL/6J mice and compared with age-matched controls (n = 11, n = 9 and n = 8, respectively). We recorded the EEG and electromyogram continuously for 48-h and conducted a 6-h sleep-deprivation. A delay in the phase angle of entrainment of locomotor activity and daily vigilance state rhythms was apparent in mice following DLAN exposure, throughout the whole age spectrum, rendering sleep characteristics similar among the three age DLAN groups and significantly different from the age-matched controls. Notably, slow-wave-activity in NREM sleep (SWA, EEG power density in 0.5–4.0 Hz) was differentially altered in young and aged DLAN mice. Particularly, SWA increased as a function of age, which was further accentuated following DLAN exposure. However, this was not found in the young DLAN animals, which were characterized by the lowest SWA levels. Concluding, long-term DLAN exposure induced more pronounced alterations in the sleep architecture of young mice, towards an aging phenotype, while it enhanced age-associated sleep changes in the older groups. Our data suggest that irrespective of age, chronic DLAN exposure deteriorates sleep behavior and may consequently impact general health.
► Exposure to light at night is common in modern society. ► Aberrant light exposure may affect mood. ► Mice housed in dim light at night increase depressive-like responses. ► Dim light at night does ...not affect hippocampus-dependent learning and memory. ► Hippocampal inflammation does not mediate light induced depressive-like responses.
Daily patterns of light exposure have become increasingly variable since the widespread adoption of electrical lighting during the 20th century. Seasonal fluctuations in light exposure, shift-work, and transmeridian travel are all associated with alterations in mood. These studies implicate fluctuations in environmental lighting in the development of depressive disorders. Here we argue that exposure to light at night (LAN) may be causally linked to depression. Male C3H/HeNHsd mice, which produce nocturnal melatonin, were housed in either a standard light/dark (LD) cycle or exposed to nightly dim (5lux) LAN (dLAN). After four weeks in lighting conditions mice underwent behavioral testing and hippocampal tissue was collected at the termination of the study for qPCR. Here were report that mice exposed to dLAN increase depressive-like responses in both a sucrose anhedonia and forced swim test. In contrast to findings in diurnal grass rats, dLAN mice perform comparably to mice housed under dark nights in a hippocampus-dependent learning and memory task. TNFα and IL1β gene expression do not differ between groups, demonstrating that changes in these pro-inflammatory cytokines do not mediate dLAN induced depressive-like responses in mice. BDNF expression is reduced in the hippocampus of mice exposed to dLAN. These results indicate that low levels of LAN can alter mood in mice. This study along with previous work implicates LAN as a potential factor contributing to depression. Further understanding of the mechanisms through which LAN contributes to changes in mood is important for characterizing and treating depressive disorders.
Artificial light, despite its widespread and valuable use, has been associated with deterioration of health and well-being, including altered circadian timing and sleep disturbances, particularly in ...nocturnal exposure. Recent findings from our lab reveal significant sleep and sleep electroencephalogram (EEG) changes owing to three months exposure to dim-light-at-night (DLAN). Aiming to further explore the detrimental effects of DLAN exposure, in the present study, we continuously recorded sleep EEG and the electromyogram for baseline 24-h and following 6-h sleep deprivation in a varied DLAN duration scheme. C57BL/6J mice were exposed to a 12:12 h light:DLAN cycle (75lux:5lux) vs. a 12:12 h light:dark cycle (75lux:0lux) for one day, one week, and one month. Our results show that sleep was already affected by a mere day of DLAN exposure with additional complications emerging with increasing DLAN exposure duration, such as the gradual delay of the daily 24-h vigilance state rhythms. We conducted detrended fluctuation analysis (DFA) on the locomotor activity data following 1-month and 3-month DLAN exposure, and a significantly less healthy rest-activity pattern, based on the decreased alpha values, was found in both conditions compared to the control light-dark. Taking into account the behavioral, sleep and the sleep EEG parameters, our data suggest that DLAN exposure, even in the shortest duration, induces deleterious effects; nevertheless, potential compensatory mechanisms render the organism partly adjustable and able to cope. We think that, for this reason, our data do not always depict linear divergence among groups, as compared with control conditions. Chronic DLAN exposure impacts the sleep regulatory system, but also brain integrity, diminishing its adaptability and reactivity, especially apparent in the sleep EEG alterations and particular low alpha values following DFA.
Up to now, EMC assessment of PLC modems has been based either on CISPR/I/PLT/89/CD1 or on CISPR/I/PLT/257/CD2. Both CDs dealt with the concept of defining test methods and limits. Besides, ...CISPR/I/301/CD3 introduced to a new concept of adding mitigation elements, as notching and power management, to the EMC assessment. Thus, a new table with frequency bands for permanent PSD reduction was created. This table is mostly in line with the table shown inside the HomePlug AV Specification4. The aim of this paper is to discuss this aspect from PLC point of view: We give some background information concerning the usage of this frequency band in Europe. Furthermore, the differences between the two tables are discussed, as well as the theoretical and estimated impact on the performance loss.
Circulating tumor cells (CTCs) are very attractive surrogate markers for systemic cancer. Currently, major efforts are being made to use these rare cells in the sense of a liquid biopsy to gain ...molecular information for rational therapeutic decision-making. The advancements in molecular analyses of CTCs down to the single-cell level have been significant in recent years and some applications are ready to be used in clinical studies. As discussed in this review, a major challenge for translating such molecular CTC-based assays into the clinic is the extremely low frequency of CTCs and the associated problems of their reliable detection and isolation. A potential solution to overcome the low CTC frequency is the recently introduced diagnostic leukapheresis that permits screening of liters of blood. Discussed here are the challenges as well as the current efforts implementing this method into clinical workflows to realize more reliable liquid biopsies.
PDF
