Decabromodiphenyl ethane (DBDPE) is a novel flame retardant that is widely used in plastics, electronic products, building materials and textiles. Our previous studies have revealed the oocyte toxicity of DBDPE, but the effect of DBDPE on preimplantation embryo development has not been reported. Here, we investigated whether and how DBDPE exposure affects preimplantation embryo development. Adult female mice were orally exposed to DBDPE (0, 5, 50, 500 μg/kg bw/day) for 14 days. First, we found that after DBDPE exposure, mice showed obvious circadian rhythm disorder. Moreover, the development of preimplantation embryos was inhibited in DBDPE-exposed mice after pregnancy. Then, we further explored and revealed that DBDPE exposure reduced the endogenous melatonin (MLT) level during pregnancy, thereby inhibiting the development of preimplantation embryos. Furthermore, we discovered that exogenous MLT supplementation (15 mg/kg bw/day) rescued the inhibition of preimplantation embryo development induced by DBDPE, and a mechanistic study demonstrated that exogenous MLT inhibited the overexpression of ROS and DNA methylation at the 5-position of cytosine (5-mC) in DBDPE-exposed preimplantation embryos. Simultaneously, MLT ameliorated the DBDPE-induced mitochondrial dysfunction by increasing the mitochondrial membrane potential (MMP), ATP, and Trp1 expression. Additionally, MLT restored DBDPE-induced changes in zona pellucida (ZP) hardness and trophectoderm (TE) cortical tension. Finally, the protective effect of MLT on embryos ameliorated the adverse reproductive outcomes (dead fetus, fetus with abnormal liver, fetal weight loss) induced by DBDPE. Collectively, DBDPE induced preimplantation embryo damage leading to adverse reproductive outcomes, and MLT has emerged as a potential tool to rescue adverse reproductive outcomes induced by DBDPE.

The increasing use of artificial light at night (ALAN) has led to exposure of freshwater ecosystems to light pollution worldwide. Simultaneously, the spectral composition of nocturnal illumination is changing, following the current shift in outdoor lighting technologies from traditional light sources to light emitting diodes (LED). LEDs emit broad-spectrum white light, with a significant amount of photosynthetically active radiation, and typically a high content of blue light that regulates circadian rhythms in many organisms. While effects of the shift to LED have been investigated in nocturnal animals, its impact on primary producers is unknown. We performed three field experiments in a lowland agricultural drainage ditch to assess the impacts of a transition from high-pressure sodium (HPS) to white LED illumination (color temperature 4000 K) on primary producers in periphyton. In all experiments, we compared biomass and pigment composition of periphyton grown under a natural light regime to that of periphyton exposed to nocturnal HPS or, consecutively, LED light of intensities commonly found in urban waters (approximately 20 lux). Periphyton was collected in time series (1–13 weeks). We found no effect of HPS light on periphyton biomass; however, following a shift to LED the biomass decreased up to 62%. Neither light source had a substantial effect on pigment composition. The contrasting effects of the two light sources on biomass may be explained by differences in their spectral composition, and in particular the blue content. Our results suggest that spectral composition of the light source plays a role in determining the impacts of ALAN on periphyton and that the ongoing transition to LED may increase the ecological impacts of artificial lighting on aquatic primary producers. Reduced biomass in the base of the food web can impact ecosystem functions such as productivity and food supply for higher trophic levels in nocturnally-lit ecosystems.

The aim of this study was to determine the impact of the fludioxonil (fdx) fungicide on the diurnal fluctuation in grapevine photosynthesis. Therefore, fdx treatment was performed at the end of flowering, at 8 am, 12 am or 7 pm. The study was performed in experimental field and several photosynthesis parameters were followed one day after treatment. Morning fdx treatment induced (i) a significant and simultaneous drop of both photosynthesis (Pn) and stomatal conductance between 8 am and 4 pm and (ii) an increase of intercellular CO2 concentration when compared to control plants. On the contrary, evening fdx treatment did not affect Pn whereas midday treatment caused Pn increase after 4 pm. These data suggest that (i) morning fdx treatment results in a non-stomatal limitation of Pn, (ii) midday treatment is more suitable to treat grapevine with fdx and (iii) a phenomenon of gating was noticed. The period of fdx spraying was an important parameter in stress response: the midday fdx treatment is more suitable to treat grapevine with fdx.

Most available exposure–response relationships for assessing crop loss due to elevated ozone (O3) have been established using data from chamber and open-top chamber experiments, using a simulated constant O3 concentration exposure (square wave), which is not consistent with the diurnal variation of O3 concentration that occurs in nature. We investigated the response of oilseed rape (Brassica napus L.) to O3 as affected by two exposure regimes: one with a diurnal variation (CF100D) and another with a constant concentration (CF100). Although the two exposure regimes have the same mean O3 concentration and accumulated O3 concentration above 40 ppb (AOT40), our results show that O3 at CF100D reduced biomass and number of pods/plant more than O3 at CF100. Both O3 exposures resulted in larger seed weights/100 pods compared to CF. Numbers of seeds/100 pods were reduced by CF100, while numbers of seeds/100 pods in the CF100D chambers were comparable to those in CF. Our results suggest that chamber experiments that use a constant O3 exposure may underestimate O3 effects on biomass and yields. Diurnal variation of O3 concentration should be considered when designing O3 exposure experiment.

Light at night (LAN) has received increasing attention for its potential health hazards to human and animals. However, to our knowledge, no study has explored the specific effects of bedroom nighttime light exposure on allostatic load (AL). To investigate the association between bedroom individual-level LAN exposure and AL among young adults, an integrative index manifests multiple system dysregulation. Using data from a cohort of 484 Chinese young adults aged 16–22 years. Bedroom light was objectively recorded at 1-min intervals for two nights using a portable illuminance meter. Fasting blood samples were collected at one-year follow-up for the detection of AL parameters. AL score was derived as sum of the top quartile of twelve physiological biomarkers in four systems: metabolic system (BMI, WC, TC, HDL, LDL, TG, HbA1c, INS, GLU); cardiovascular system (SBP, DBP); immune and inflammatory systems (hs-CRP), with HDL was lowest quartile. Univariate and multivariate linear regression models were used to evaluate the association between LAN intensity with AL score and separate AL parameters. The average age of subjects was 18.7 years, 64.3% were female. The mean AL score of LAN group (average LAN intensity ≥ 3lx) was significantly higher than Dim group (3.6 ± 2.6 vs. 2.7 ± 2.1; P = 0.007). For each 1 lx increase of LAN intensity was associated with 0.15-unit increase in AL score (95% CI: 0.06, 0.24; P = 0.001). Moreover, LAN group was associated with increased 1.01-unit in AL score (95% CI: 0.36–1.66; P = 0.003) compared to Dim group. Significant associations between bedroom LAN exposure with allostatic load and separate AL biomarkers were observed in our study. Keeping bedroom darkness at night may be a practicable option to reduce the wear of multiple body systems and improve human cardiometabolic health from early in life.

Artificial light is transforming the nighttime environment and quickly becoming one of the most pervasive pollutants on earth. Across taxa, light entrains endogenous circadian clocks that function to synchronize behavioral and physiological rhythms with natural photoperiod. Artificial light at night (ALAN) disrupts these photoperiodic cues and has consequences for humans and wildlife including sleep disruption, physiological stress and increased risk of cardiovascular disease. However, the mechanisms underlying organismal responses to dim ALAN, resembling light pollution, remain elusive. Light pollution exists in the environment at lower levels (<5 lux) than tested in many laboratory studies that link ALAN to circadian rhythm disruption. Few studies have linked dim ALAN to both the upstream regulators of circadian rhythms and downstream behavioral and physiological consequences. We exposed zebra finches (Taeniopygia gutatta) to dim ALAN (1.5 lux) and measured circadian expression of five pacemaker genes in central and peripheral tissues, plasma melatonin, locomotor activity, and biomarkers of cardiovascular health. ALAN caused an increase in nighttime activity and, for males, cardiac hypertrophy. Moreover, downstream effects were detectable after just short duration exposure (10 days) and at dim levels that mimic the intensity of environmental light pollution. However, ALAN did not affect circulating melatonin nor oscillations of circadian gene expression in the central clock (brain) or liver. These findings suggest that dim ALAN can alter behavior and physiology without strong shifts in the rhythmic expression of molecular circadian pacemakers. Approaches that focus on ecologically-relevant ALAN and link complex biological pathways are necessary to understand the mechanisms underlying vertebrate responses to light pollution.

Benzo[a]pyrene (BaP), a widely existed polycyclic aromatic hydrocarbon pollutant in aquatic environment, has toxic effects on marine animals and their generations, but the intergenerational immunotoxic mechanism underlying has not been clearly understood. In the study, the offspring of marine medaka (oryzias melastigma) which were exposed to 0.5 μg L⁻¹ BaP suffered from circadian rhythm oscillation disorders and severe DNA damage. Many clock-associated genes like per1 were significantly modulated in offspring, both per1 and p53 were significantly inhibited that altered the progression of cell cycle and inhibited DNA repair, which possibly resulted in the increased mortality of offspring. The hypermethylation of the per1 promotor and abnormal levels of N⁶-methyladenosine (m⁶A) suggested that the underlying mechanism was probably related to the epigenetic modification. Moreover, the offspring from paternal BaP exposure had more severe DNA damage and a higher degree of hypermethylation than those from maternal exposure. F1 larvae from BaP-exposed parents were more sensitive to BaP exposure, showing that the expression of immune and metabolism-related genes were significantly up-regulated. Taken together, the parental toxicity induced by BaP could be passed to F1 generation and the mechanism underlying was probably associated with a characteristic circadian rhythm disorder.

Increasing urbanisation is altering the physiology of wild animals and the mechanisms involved are largely unknown. We hypothesised that altering the physiology of urban organisms is due to the effect of extra light at night on the circadian clock by modulating the expression of pineal machinery and clock genes. Two experiments were performed. In Experiment 1, immediately after being procured from their respective sites (urban and rural sites), birds were released individually in LLdᵢₘ light conditions. Circadian rhythm period, activity duration, and total activity count were calculated and did not differ between urban and rural birds. In Experiment 2, birds (from urban and rural habitats) were sampled at six time points at regular 4-h intervals, beginning 1 h after sunrise. We measured daily variations in plasma melatonin levels. We also analysed the expression levels of Aanat, Mel1A and Mel1B as an indicator of melatonin biosynthesis and action machinery. Clock and clock-controlled genes (Bmal1, Clock, Per2, Per3, Cry1 and Npas2) were studied in the hypothalamus, the pineal gland, and retina to investigate the effects of urban habitats on the circadian clock. Our results show that there is a lower expression of Aanat in the pineal gland and relatively low plasma melatonin levels in urban birds. Further, clock genes are also differentially expressed in all three central tissues of urban birds. We propose that alterations in the melatonin biosynthesis machinery and the expression of clock genes could result in miscalculations in the internal timing of the organism, with environmental timings leading to altered physiology in urban wild animals.

Accurately determining methane emission factors of dairy herd in China is imperative because of China’s large population of dairy cattle. An inverse dispersion technique in conjunction with open-path lasers was used to quantify methane emissions from a dairy feedlot during the fall and winter seasons in 2009–2010. The methane emissions had a significant diurnal pattern during both periods with three emission peaks corresponding to the feeding schedule. A 10% greater emission rate in the fall season was obtained most likely by the higher methane emission from manure during that period. An annual methane emission rate of 109 ± 6.7 kg CH₄ yr⁻¹ characterized with a methane emission intensity of 32.3 ± 1.59 L CH₄ L⁻¹ of milk and a methane conversion factor (Yₘ) of 7.3 ± 0.38% for mature cattle was obtained, indicating the high methane emission intensity and low milk productivity in Northern China.

Trends were found for increasing surface ozone concentrations during April-September in northern Sweden over the period 1990-2006 as well as for an earlier onset of vegetation growing season. The highest ozone concentrations in northern Sweden occurred in April and the ozone concentrations in April showed a strong increasing trend. A model simulation of ozone flux for Norway spruce indicated that the provisional ozone flux based critical level for forests in Europe is exceeded in northern Sweden. Future climate change would have counteracting effects on the stomatal conductance and needle ozone uptake, mediated on the one hand by direct effect of increasing air temperatures and on the other through increasing water vapour pressure difference between the needles and air. Thus, there is a substantial and increasing risk for negative impacts of ozone on vegetation in northern Sweden, related mainly to increasing ozone concentrations and an earlier onset of the growing season. Increasing risks for ozone impacts on vegetation in northern Sweden.