Abstract P167: Chronic Circadian Disruption Impairs Cardiovascular Rhythms In Mice

Shift workers have an increased risk of developing hypertension and higher incidence of metabolic syndrome. Circadian rhythm disruption increases cardiometabolic disease risk in humans and animals. We hypothesized that chronic circadian disruption (CCD) disrupts blood pressure, heart rate, and locomotor activity rhythms. Male 8-week old C57BL/6J mice were under a standard light/dark cycle (12-h light, 12-h dark, control) or a CCD protocol (10-h light, 10-h dark, T20) with ad libitum food and water for 10 weeks. T20 mice gained significantly more body weight (n=6, p=0.04; time: p<0.001, light cycle: p<0.001). Mean arterial pressure (MAP), heart rate (HR), and locomotor activity were measured by telemetry after 10 weeks of CCD. Average MAP, HR, and activity were calculated during light and dark periods. MAP between the light and dark periods was significantly different in control mice (12:12 LD), while T20 mice (10:10 LD) did not show diurnal variation (Control 119±3 mm Hg vs.101±2 mm Hg, dark vs. light, respectively, p<0.001; T20 114±13 mm Hg vs.113±12 mm Hg, dark vs. light, respectively, p=0.86; n=3-4 in all groups). Control mice showed a diurnal variation in HR, whereas T20 mice did not show a light-dark difference (Control 584±11 bpm Hg vs. 511±4 bpm, dark vs. light, respectively, p=0.001; T20 537±14 bpm vs. 526±5 bpm, dark vs. light, respectively, p=0.48; n=3-4 in all groups). Dark phase HR was significantly decreased in T20 mice (p=0.01, control dark vs. T20 dark). Control mice showed a light-dark difference in activity, while T20 mice lacked diurnal variation in the activity rhythm (Control 9.6±1.3 counts/min Hg vs. 3.1±0.3 counts/min, dark vs. light, respectively, p<0.001; T20 6.9±0.3 counts/min vs. 6.0±0.8 counts/min, dark vs. light, respectively, p=0.92; n=3-4 in all groups). T20 mice also displayed significantly higher activity during the light phase (p=0.04, control light vs. T20 light). Time of day and the interaction between time of day and light cycle, respectively, were significant between control and T20 mice for MAP, HR, and activity (n=3-4, MAP: p=0.001 and p=0.002; HR: p=0.001 and p=0.004; Activity: p=0.001 and p=0.004). These results indicate that CCD impairs cardiovascular and behavioral rhythms, which may lead to cardiovascular disease.

Wavelength-dependent effects of artificial light at night on phytoplankton growth and community structure

Artificial light at night (ALAN) is increasingly recognised as a disruptive form of environmental pollution, impacting many physiological and behavioural processes that may scale up to population and community-level effects. Mounting evidence from animal studies show that the severity and type of the impact depends on the wavelength and intensity of ALAN. This knowledge has been instrumental for informing policy-making and planning for wildlife-friendly illumination. However, most of this evidence comes from terrestrial habitats, while research testing alternative wavelength illumination in marine environments is lagging behind. In this study we investigated the effect of such alternative ALAN colours on marine primary producers. Specifically, we tested the effect of green, red, and natural white LED illumination at night, compared to a dark control, on the growth of a green microalgae as well as the biomass, diversity and composition of a phytoplankton assemblage. Our findings show that green ALAN boosted chlorophyll production at the exponential growth stage, resulting in higher biomass production in the green algae Tetraselmis suesica. All ALAN wavelengths affected the biomass and diversity of the assemblage with the red and green ALAN having the stronger effects, leading to higher overall abundance and selective dominance of specific diatom species compared to white ALAN and the dark control.SynthesisOur work indicates that the wavelength of artificial light sources in marine areas should be carefully considered in management and conservation plans. In particular, green and red light should be used with caution in coastal areas, where there might be a need to strike a balance between the strong effects of green and red light on marine primary producers with the benefit they bring to other organisms.

Hubungan Durasi Paparan Gelombang Elektromagnetik Telepon Seluler Terhadap Kadar Melatonin Pada Tikus Putih (Rattus norvegicus) Galur Wistar

Background : Mobile Phone (MP) is a wireless communication tools that nowadays used by people with many features that can ease the user. Cellphone is releasing electromagnetic radiation that can causes side effect for the user itself, one example of the side effect is disturbing the melatonin hormone synthesis that can cause the abnormal sirkadian body rythm, so the sleep patterns are disrupted, causing insomnia, islam is teaching us to keep our health, for example is to keep the rythm of our bedtime regularly. Objective : Knowing the relation between exposure duration of mobile phone electromagnetic radiation to melatonin level of Wistar albino rats observed by medicine and islam perspectives. Methods : This study was experimental study, total sample was determined by frederer theory and analyzed using IBM SPSS Statistic 21 for Windows. Results : The results showed that melatonin levels in the positive control group (dark control group) 13,705 ± 0,500 were compared with the group which exposed for 3 hours 13,375 ± 0,654 with (p=0,299) and in the positive control group (dark control group) 13,705 ± 0,500 compared with the group which exposed for 6 hours 13,223 ± 0,529 with (p=0,116). Conclusions : There is no significant relation between exposure duration of mobile phone electromagnetic radiation to melatonin levels in Wistar albino rats.

Bacterioplankton Activity in a Meso-eutrophic Subtropical Coastal Lagoon

The aim of this study was to investigate whether the bacterioplankton activity in the meso-eutrophic Conceição Lagoon would increase significantly under allochthonous inputs of inorganic nutrients and organic carbon. Abundance and biomass of bacterioplankton were evaluated under three treatments: light (14 h light/10 h dark), complete darkness (dark-control), and nutrient (C + N + P—dark, 100 : 10 : 1) enrichments during 72 h. Nutrient enrichments promoted a significant increase in abundance (maximum of 19.0 ×109 cells·L−1 in the first 32 hours) and biomass of the heterotrophic bacterioplankton, which induced the formation of large clusters. Bacterial biomass remained constant in the non-enriched incubations (dark-control and light). Bacterial growth rates were significantly higher after nutrient additions (1.35 d−1), followed by control (0.79 d−1), and light (0.63 d−1) treatments, which were statistically equal (p>0.05). Bacterial production rates were also significantly higher under nutrient additions (1.28 d−1), compared to the control and light (0.50 d−1 and 0.44 d−1, respectively), demonstrating that bacterial growth and production in this meso-eutrophic lagoon are under an immediate “bottom-up” regulation, followed by a potential top-down effect. These facts reinforce the urgency on improving the local wastewater management plan in order to prevent further expansion of anoxic waters.

Light modulates activity and expression of glutamine synthetase isoforms in maize seedling roots

In maize roots, continuous illumination inhibits chloroplastic glutamine synthetase (GS2) activity, which decreased in light from 72.8% in 4-day-old to 26% in 10-day-old plants. In dark-adapted plants transferred to light for 6 days, GS2 activity declined from 100% to 41%, but in light-adapted plants transferred to darkness, it increased to the level of the dark control. Changes of cytosolic (GS1) activity were minor, with a similar trend. Quantitative RT-PCR revealed that light/dark treatments moderately affected only transcription of GS1 isoforms, with the exception of GS1-2, which was dramatically induced by darkness and repressed by light.

Photoinhibition of Respiration in Epilithic Periphyton

To determine whether respiration in the light was equal to respiration in the dark we examined epilithic periphyton from a lake acidified experimentally with sulfuric acid. Because of the low concentrations of dissolved inorganic carbon, we could use both 12C and 14C uptake techniques. Using the 14C technique we could correct for residual photosynthesis in samples treated with the photosynthetic inhibitor DCMU (3-(3,4-dichlorophenyl)-1,1-dsmethyiurea). DCMU did not alter rates of dark respiration. However, respiration of DCMU-treated samples in the light was less than in the dark (P < 0.01). This photoinhibition of respiration was about 40% of dark control values. If we had calculated gross photosynthesis for the specific conditions of this experiment, but assumed incorrectly that light and dark respiration were equal, we would have overestimated gross photosynthesis by about 30%. Thus, if the ratio of respiration to photosynthesis is high, researchers will have to evaluate the effect of light on respiration to better estimate gross photosynthesis. The technique we describe, of monitoring both 12C and 14C flux in DCMU-treated samples in the light, will provide an underestimate of respiration in the light.