Apoptosis development pathways in human lymphocytes induced by UV light and reactive oxygen species

We have studied alterations in the structural state of DNA, the level of membrane Fas-receptor expression, functional activity of caspase-3, the concentration of Ca²⁺, p53 and cytochrome c proteins in human lymphocyte cells in the dynamics of apoptosis, induced by UV light (240–390 nm) at doses of 151, 1510, and 3020 J/m² and reactive oxygen species (ROS): superoxide anion radical, hydroxyl radical, hydrogen peroxide, and singlet oxygen. It was established that UV light and ROS induce lymphocyte DNA fragmentation after the incubation of a modified cell for 20 h. It was shown that in 1–5 h after UV light and ROS exposure on lymphocytes, an increase is observed in the level of membrane death Fas-receptors as compared to intact cells. Enhancement was revealed in the functional activity of lymphocyte caspase-3 4 h after the generation of singlet oxygen, hydroxyl radical, and the addition of hydrogen peroxide, as well as 8 and 24 h and 6 and 8 h of UV irradiation of cells at doses of 151 and 1510 J/m², respectively. Using the DNA comet approach, it was revealed that DNA damage (single-stranded breaks) appears approximately 15–20 min after UV irradiation of lymphocytes at doses of 1510 and 3020 J/m² and the addition of hydrogen peroxide at a concentration of 10⁻⁶ mol/L (comets of the C1 type) and reaches its maximum 6 h after cell modification (comets of the C2 and C3 types). Six hours after exposure of lymphocytes to hydrogen peroxide and UV light at doses of 1510 and 3020 J/m², it was established that the p53 level increased in the investigated cells. It was established that under UV light exposure and exogenous generation of reactive oxygen species, the increase in the calcium level in lymphocyte cytoplasm is determined by Ca²⁺ efflux from the intracellular depots as a result of activation of the components of the phosphoinositide information transmission mechanism to a cell. A hypothesis was proposed on the correlation between changes in the calcium level and initiation of programmed cell death in human lymphocytes after UV light and ROS exposure. It was concluded that the lead role is played by receptor-mediated (Fas-dependent) caspase and p53-dependent pathways in the development of lymphocyte apoptosis induced by exposure to UV light at doses of 151 and 1510 J/m² and reactive oxygen metabolites. A scheme is presented which considers possible intracellular events leading to apoptotic death of lymphocytes after UV irradiation.     

Proliferation and tumorigenity of murine hepatoma cells irradiated with polychromatic visible and infrared light

In experiments in vitro, the effects of polychromatic visible (VIS) light combined with polychromatic infrared light (VIS-IR, 480–3400 nm) and the effects of the entire spectrum of VIS radiation (385–750 nm) on viability and proliferative activity of the murine hepatoma cells MH22a were studied. In experiments in vivo, changes in the tumorigenic properties of cells MH22a were studied after the same kinds of light exposure. It was shown that irradiation of hepatoma cells with two kinds of polychromatic light at a wide range of doses (4.8–38.4 J/cm²) did not lead to an increase in the number of dead cells for 24–72 h of cultivation and did not cause deceleration of the hepatoma cell proliferation; moreover, the VIS-IR light at a dose of 4.8 J/cm² and the VIS light at a dose 38.4 J/cm² even promoted more intense cell proliferation after 24 h. In cells irradiated with VIS-IR and VIS light, the proliferation index rose by 1.6 and 1.4 times, respectively, and the time of the cells’ number doubling decreased as compared with control. Studying the tumorigenic properties of irradiated tumor cells has shown that, for 30 days after transplantation to syngenic mice C3HA of hepatoma cells 24 h after their irradiation with VIS-IR light at a dose of 4.8 J/cm², the tumor volume decreased significantly (2.6–4.1 times) at all periods of observation, while the incidence of tumor formation decreased, whereas the survival of the tumor-bearing mice did not change. Transplantation of cells irradiated with the same light at a dose of 9.6 J/cm² did not lead to significant changes in the tumor volume, the tumor formation incidence, and animal survival. The main contribution to the antitumor effect of VIS-IR light seems to be made by the VIS component, as transplantation into mice of cells irradiated with VIS light alone at a dose of 38.4 J/cm² also stimulating proliferation of hepatoma cells in vitro resulted in a decrease of their tumorigenic properties. However, the IR component in the combined VIS-IR radiation enhanced the antitumor effect of the VIS light; as a result, it was manifested after use of doses eight times lower (4.8 J/cm²) than in the case of VIS light alone (38.4 J/cm²). Mechanisms of the decrease of tumorigenic properties of hepatoma cells after irradiation with polychromatic light at doses stimulating their proliferation in vitro are studied.     

Action of ultraviolet-C on stilbene formation in callus ofArachis hypogaea

The action of light on the formation of stilbenes and the induction of stilbene synthase in dark-grown and light-grown callus of peanut (Arachis hypogaea) was investigated over the wavelength range from 250 to 400 nm. Ultraviolet light of 260–270 nm had a significant and selective effect on the formation of resveratrol and isopentenylresveratrol. The callus responded by the production of stilbene synthase, with maximal activity appearing 4 h after irradiation with a fluence rate of 1 W m^-2 (270 nm) applied for 10 min. At lower fluence rates, maximal responses in enzyme activity were shifted to longer induction periods. The efficiency of the biosynthetic pathway, and the form and maxima of enzyme profiles depended on the duration of exposure. We failed to demonstrate any significant influence of red light at low energy irradiation (672 nm, 726 nm and 753 nm).     

Synthesis and characterization of erbium‐doped YAlO3 phosphor

In the yttrium aluminium system, the YAlO₃ phosphor is a prominent host because of the yttrium aluminium ratio (1:1). Phosphor was synthesized by the solid‐state reaction method at variable concentrations of erbium (0.1–2.5 mol%). This method is suitable for large‐scale production and is a less time‐consuming method when compared with the soft synthesis method. The prepared sample was characterized by X‐ray diffraction technique and the crystallite size was calculated by Scherer's formula. Vibrational and bending analysis of prepared phosphor for optimized concentration of erbium ion is described based on the Fourier transform infrared spectroscopic technique. The photoluminescence (PL) emission spectra of prepared phosphor for variable concentrations of erbium ion were recorded and the excitation spectrum was found to be at 291 nm with three shoulder peaks at 305, 270 and 242 nm. For 291 nm excitation, the emission spectrum was found at 546 nm and 552 nm. PL intensity increased with increasing concentrations of erbium and after 2 mol% emission intensity decreased due to concentration quenching. Spectrophotometric determination of YAlO₃:Er³⁺ is described by CIE co‐ordinates and shows an intense emission in the green region such that the prepared phosphor can act as a single host for green light emission. Thermoluminescence glow curve analysis of the YAlO₃:Er³⁺ phosphor was recorded for different ultraviolet (UV) light exposures and gamma exposure. Different gamma doses 0.5–2 kGy show a linear response. Kinetic parameters were calculated by the peak shape method. Copyright © 2015 John Wiley & Sons, Ltd.     

Ultrastructure of the vegetative gametophytic cells of Porphyra leucosticta (Rhodophyta) grown in red, blue and green light

The ultrastructure of the vegetative gametophytic cells of Porphyra leucosticta Thuret grown in red, blue and green light was studied both in ultrathin sections and in replicas of rapidly frozen cells. High activity of dictyosornes and mucilage sacs results in a dramatic decrease of the protoplasmic area and in thicker cell walls in red light in comparison with blue light and the control. There are numerous well‐formed phycobili‐somes in blue light, whereas not well‐formed ones are present in red and especially in green light. There are also many phycobilisomes in the intrapyrenoidal thylakoids in blue light, fewer in green light, but they are absent in red light and in the control. It seems that in red and especially in green light, the phycobilisomes have fewer rods than in blue light. In green light, chloroplasts bear numerous genophores in contrast to blue and red light. The spacings of neighboring parallel thylakoids are as follows: control 64.3 nm, blue light 90.6 nm, red light 41.3 nm, green light 43.7 nm. Due to the relatively small spacing of the neighboring parallel thylakoids in red (41.3 nm) and in green light (43.7 nm) and of the given height of phycobilisomes (35 nm), the alternate phycobilisomes attached to neighboring lamellae are forced to interdigitate. The density of phycobilisomes per square micrometer of thylakoid surface dramatically increases in blue light (800 μm^?2) in relation to red (250 μm^?2) and green light (180 μm^?2). The protoplasmic fracture face of the thylakoids reveals numerous, tightly packed, but randomly distributed particles. The particle size distribution is uniform in the two types of fracture faces, with an average diameter of about 11.5 nm. In blue light, both the phycobilisomes and exoplasmic face particles are organized into rows with a spacing of 60–70 nm. The results (changes: in the protoplasmic area; in the spacing of the thylakoids; in phycobilisome arrangement; in structure, shape and size of phycobilisomes; and in the accumulation of plastoglobuli), have shown that the monochromatic light (blue, red and green) brings about marked changes in the package effect and consequently in the efficiency of light absorption. In addition, the blue light contributes to the intense production of chlorophyll a, phycoerythrin, phycocyanin and soluble proteins, while intense production of polysaccharidic material is attributed to red light.     

Photoinhibition of Photosynthetic Oxygen Production and its Recovery in the Subtidal Red Alga Polyneura hilliae

In the marine red alga Polyneura hilliae photoinhibition of photosynthesis was investigated by measuring the photosynthetic oxygen production. The extent of photoinhibition in this alga depends on the fluence rate as well as on the time of exposure. Strongly photoinhibited algae recover slowly. Full recovery is reached only in weak light after 3 days. Two phases of recovery can be distinguished: a first relatively fast phase of recovery that is independent of light, and a second slow phase which begins after about 6 hours and requires weak light. Consequently, even in complete darkness partial recovery is observed. An action spectrum of photoinhibition and its comparison with the in vivo absorption spectrum of Polyneura demonstrates that photoinhibition is mainly caused by light which is absorbed by phycobiliproteins, chlorophyll a and carotenoids. This fact and the ineffectiveness of light above 686 nm clearly indicate that the main photoinhibition site in this alga is PS II. No photosynthetic oxygen production is detectable after 3 h irradiation at 402 nm, 150 μmol quanta m^?2s^?1. As photosynthetic activity recovers slowly and to a limited extent, the suppression of oxygen production is apparently only in part the result of photoinhibition sensu strictu and in part due to permanent photodamage.     

UV‐B INDUCTION OF UV‐B PROTECTION IN ULVA PERTUSA (CHLOROPHYTA)1

The green macroalga Ulva pertusa Kjellman produced UV‐B absorbing compounds with a prominent absorption maximum at 294 nm in response only to UV‐B, and the amounts induced were proportional to the UV‐B doses. Under a 12:12‐h light:dark regime, the production of UV‐absorbing compounds occurred only during the exposure periods with little turnover in the dark. There was significant reduction in growth in parallel with the production of UV‐B absorbing compounds. The polychromatic action spectrum for the induction of UV‐B absorbing compounds in U. pertusa exhibits a major peak at 292 nm with a smaller peak at 311.5 nm. No significant induction was detected above 354.5 nm, and radiation below 285 nm caused significant reduction in the levels of UV‐B absorbing compounds. After UV‐B irradiation at 1.0 W·m^?2 for 9 h, the optimal photosynthetic quantum yield of the samples with UV‐B absorbing compounds slightly increased relative to the initial value, whereas that of thalli lacking the compounds declined to 30%–34% of the initial followed by subsequent recovery in dim light of up to 84%–85% of the initial value. There was a positive and significant relationship between the amount of UV‐B absorbing compounds with antioxidant activity as determined by the α,α‐diphenyl‐β‐picrylhydrazyl scavenging assay. In addition to mat‐forming characteristics and light‐driven photorepair, the existence and antioxidant capacity of UV‐B absorbing compounds may confer U. pertusa a greater selective advantage over other macroalgae, thereby enabling them to thrive in the presence of intense UV‐B radiation.     

Effects of weak laser radiation (632.8 nm) on isolated mouse immune cells

The dose dependence of in vitro effects of low-intensity radiation of a He-Ne laser (632.8 nm, 0.2 mW/cm²) on the functional activity of peritoneal macrophages and lymphocytes of mouse spleen was studied. The exposure of isolated cells was varied from 5 to 180 s. If the exposure did not exceed 60 s, stimulation of secretory activity was observed: increased production of interleukin 2, interferon γ, and interleukin 6 in lymphocytes; increased production of tumor necrosis factor α, nitric oxide, and interleukin 6 in macrophages; and enhanced activity of natural killer cells. A longer exposure (up to 180 s) either had no effect on the synthesis of certain cytokines (interleukin 2 in lymphocytes and interleukin 6 in macrophages) or inhibited it, which was expressed in decreased production of interleukin 6 and interferon γ in lymphocytes and nitric oxide in macrophages, as well as in suppression of the activity of natural killer cells. Conversely, the production of interleukin 3 decreased after a short-term exposure but increased after 180-s irradiation. The high sensitivity of cells to extremely weak laser light also manifested itself as a considerable increase in expression of the inducible heat shock protein 70; this effect was observed at all doses studied, including the 5-s exposure. In contrast, expression of the heat shock protein 90 slightly decreased after irradiation of cells with laser light.     

Red and near-infrared light induces intracellular Ca2+ flux via the activation of glutamate N-methyl-D-aspartate receptors

Red and near-infrared (NIR) light effect on Ca²⁺ ions flux through the influence on N-methyl-D-aspartate receptors (NMDARs) and their functioning in HeLa cells was studied in vitro. Cells were irradiated by 650 and 808 nm laser light at different power densities and doses and the obtained effect was compared with that caused by the pharmacological agents. The laser light was found to elevate Ca²⁺ influx into cell cytoplasm in a dose-dependent manner without changes of the NMDAR functioning. Furthermore, the light of both wavelengths demonstrated the ability to elevate Ca²⁺ influx under the pharmacological blockade of NMDARs and also might partially abolish the blockade enhancing Ca²⁺ influx after selective stimulation of the receptors with NMDA. Simultaneously, the light at moderate doses demonstrated a photobiostimulating effect on cells. Based on our experiments and data reported in the literature, we suggest that the low-power visible and NIR light can instigate a cell membrane depolarization via nonthermal activation, resulting in the fast induction of Ca²⁺ influx into cells. The obtained results also demonstrate that NIR light can be used for nonthermal and nonpharmacological stimulation of NMDARs in cancer cells.     

In vivo and in vitro activation of macrophages with a cyanine photosensitizing dye,platonin

A cyanine photosensitizing dye, platonin, is a potent macrophage-activating agent. Four days after the administration to mice of small amounts of platonin (20–40 ng/mouse), peritoneal macrophages exhibited greatly enhanced Fc-receptor-mediated phagocytic and superoxide-generating capacities. Much higher doses (more than 3000 ng/mouse) did not have this effect. Photodynamic experiments for macrophage activation were performed by exposing mouse peritoneal cells (mixture of macrophages and B and T lymphocytes) to white fluorenscent light (3 J m^–2s^–1) in media containing various low concentrations of platonin. A short exposure to white fluorescent light (5 s, 15 J m^–2) of peritoneal cells in a medium containing 3 ng platonin/ml produced a maximal level of phagocytic capacity of macrophages. Although platonin absorbs light poorly at wavelengths longer than 630 nm, the region of the spectrum in which the tissues are transparent allows reasonable penetration of light. Thus, we designed experiments in which peritoneal cells were exposed to a red fluorescent light (0.5 J m^–2s^–1). In a medium containing 10 ng platonin/ml with 15 J m^–2 red light, a markedly enhanced ingestion activity of macrophages was observed. Photodynamic treatment of peritoneal macrophages alone did not activate macrophages. Thus, participation of nonadherent cells is required for photodynamic activation of macrophages, implying that a macrophage-activating factor is generated within the nonadherent cells and transmitted to macrophages.     

The effect of radiation with polychromatic visible and infrared light on the tumorigenicity of murine hepatoma 22A cells and their sensitivity to lysis by natural killers

The tumorigenicity of murine hepatoma cells (MH-22a) and their sensitivity to lysis by natural killers (NKs) have been studied after exposure to polychromatic visible and infrared light (VIS-IR, 480–3400 nm, 40 mW/cm²), similar to the terrestrial solar spectrum without its minor UV component, with the aim of clarifying the participation of this important environmental and physiotherapeutic factor in regulation of antitumor protective system. MH-22 cells were exposed in vitro to VIS-IR light and their sensitivity to lytic activity of NKs was evaluated. It was found that, after exposure to VIS-IR light at a dose of 4.8 J/cm², the sensitivity of MH-22a cells to lysis by NKs increased by 1.5–2 times, while after exposure at a dose of 9.6 J/cm² it did not change at all the ratios of the NKs-number (effectors) to that of hepatoma cells — targets (1 : 5–1 : 50). An increase of the hepatoma cell sensitivity to NKs was accompanied by structural changes of cell surface: the capability of supramembranous glycoproteins (glycocalyx) to sorb the vital dye alcian blue (AB) was significantly lower than in the case of unexposed cells of the control group. However, no changes in AB sorption was revealed in hepatoma cells exposed to light at a dose of 9.6 J/cm². The tumorigenicity of photoirradiated MH-22a cells has been studied in the experiments in vitro. For 25 days after transplantation of light-exposed hepatoma cells to C3HA syngene mice, the tumor volume proved to be smaller after exposure to light at both doses of 4.8 and 9.6 J/cm² than in the control group (by 4–4.5 times and 2.5–4 times, respectively), which correlated with an increase of sensitivity to lysis by NKs and with a decrease of AB sorption after light exposure only at a dose of 4.8 J/cm². Using the flow-cytometry method, we could show that VIS-IR light at the doses used did not interfere with the distribution of hepatoma cells over the cell-cycle phases and, thus, deceleration of the tumor growth was not associated with a cytostatic effect of the VIS-IR light. To evaluate the effect of polychromatic light on growth of the preformed tumors, a 5-day course of daily light exposure of C3HA tumor-bearing mice was performed on the 10th day after subcutaneous transplantation of 2 × 10⁵ cells of syngene hepatoma, when tumors developed in all (100%) animals. As in the case of transplantation of light-exposed cells, irradiation of tumor-bearing mice at doses 4.8–9.6 J/cm² resulted in a deceleration of tumor growth (by 2.1–2.9 and 2,2 times, respectively) for 4 weeks compared with unirradiated mice.     

PD-1 and Tim-3 Pathways Regulate CD8+ T Cells Function in Atherosclerosis

T cell-mediated immunity plays a significant role in the development of atherosclerosis (AS). There is increasing evidence that CD8⁺ T cells are also involved in AS but their exact roles remain unclear. The inhibitory receptors programmed cell death-1 (PD-1) and T cell immunoglobulin and mucin domain 3 (Tim-3) are well known inhibitory molecules that play a crucial role in regulating CD8⁺ T cell activation or tolerance. Here, we demonstrate that the co-expression of PD-1 and Tim-3 on CD8⁺ T cells is up-regulated in AS patients. PD-1⁺ Tim-3⁺ CD8⁺ T cells are enriched for within the central T (T_CM) cell subset, with high proliferative activity and CD127 expression. Co-expression of PD-1 and Tim-3 on CD8⁺ T cells is associated with increased anti-atherogenic cytokine production as well as decreased pro-atherogenic cytokine production. Blockade of PD-1 and Tim-3 results in a decrease of anti-atherogenic cytokine production by PD-1⁺ Tim-3⁺ CD8⁺ T cells and in an augmentation of TNF-α and IFN-γ production. These findings highlight the important role of the PD-1 and Tim-3 pathways in regulating CD8⁺ T cells function in human AS.     

Rhodobacter sphaeroides RV cultivation and hydrogen production in a one- and two-stage chemostat

Rhodobacter sphaeroides RV cultivation and hydrogen production were studied in a one- and two-stage chemostat using lactic acid as substrate. Light saturation was observed when light intensities equal to or above 10 klx were applied. Under light saturation, the two-stage chemostat appeared to be very effective for hydrogen production, allowing complete nitrogen removal by bacterial growth in the first reactor. The hydrogen evolution rate in the second reactor was up to 75 ml H₂ (g dry weight)^–1 h^–1. Accumulation of storage material was observed in the second reactor of the two-stage chemostat under a large carbon excess and limiting light irradiance. The optimal hydraulic residence time was 15 h for both stages, leading to a total hydrogen production about 40% higher than in the one-stage chemostat. Under increasing influent ammonium and yeast extract concentrations, opposite trends of decreasing bacterial activity and increasing concentration resulted in a linear increase of the overall hydrogen production to 1.4–1.6lH₂ (l reactor)^–1 day^–1. Hydrogen production quickly fell when nitrogen was not completely metabolised. The hydrogen evolution rate was also found to depend on lactic acid concentration, and maximum bacterial activity was observed at 100 mM influent lactic acid.     

Influence of Constant Light and Darkness,Light Intensity,and Light Spectrum on Plasma Melatonin Rhythms in Senegal Sole

Light is the most important synchronizer of melatonin rhythms in fish. This paper studies the influence of the characteristics of light on plasma melatonin rhythms in sole. The results revealed that under long‐term exposure to constant light conditions (LL or DD), the total 24 h melatonin production was significantly higher than under LD, but LL and DD conditions influenced the rhythms differently. Under LL, melatonin remained at around 224 pg/ml throughout the 24 h, while under DD a significant elevation (363.6 pg/ml) was observed around the subjective evening. Exposure to 1 h light pulses at MD (mid‐dark) inhibited melatonin production depending on light intensity (3.3, 5.3, 10.3, and 51.9 µW/cm²). The light threshold required to reduce nocturnal plasma melatonin to ML (mid‐light) values was 5.3 µW/cm². Melatonin inhibition by light also depended on the wavelength of the light pulses: while a deep red light (λ>600 nm) failed to reduce plasma melatonin significantly, far violet light (λ_max=368 nm) decreased indoleamine's concentration to ML values. These results suggest that dim light at night (e.g., moonlight) may be perceived and hence affect melatonin rhythms, encouraging synchronization to the lunar cycle. On the other hand, deep red light does not seem to inhibit nocturnal melatonin production, and so it may be used safely during sampling at night.     

Delphinidin Activates NFAT and Induces IL-2 Production Through SOCE in T Cells

Delphinidin is an anthocyanidin that possesses antioxidant and anti-inflammatory effects; however, some reports suggest that delphinidin has pro-inflammatory properties. For this reason, we assessed the effect of delphinidin on cytokine production in T cells. We demonstrated that delphinidin increased the cytosolic-free Ca²⁺ concentration by releasing Ca²⁺ from intracellular stores and increasing Ca²⁺ entry. The putative Ca²⁺ release activated Ca²⁺ (CRAC) channel inhibitors BTP2 and gadolinium reduced the calcium entry stimulated by the anthocyanidin. Delphinidin induced nuclear factor of activated T cells (NFAT) translocation and NFAT-Luc activity in Jurkat cells and was dependent on the CRAC channel and calcineurin pathway. Delphinidin increased the mRNA expression and production of IL-2 in Jurkat cells and was inhibited by BTP2 and cyclosporine A. Using peripheral blood lymphocytes, we demonstrated that delphinidin increased the production of IL-2 and IFN-γ and was inhibited by BTP2. Taken together, our results suggest that delphinidin exerts immunostimulatory effects on T cells by increasing cytokine production through CRAC channel and NFAT activation.     

Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese

UVC light is a widely used sterilization technology. However, UV lamps have several limitations, including low activity at refrigeration temperatures, a long warm-up time, and risk of mercury exposure. UV-type lamps only emit light at 254 nm, so as an alternative, UV light-emitting diodes (UV-LEDs) which can produce the desired wavelengths have been developed. In this study, we validated the inactivation efficacy of UV-LEDs by wavelength and compared the results to those of conventional UV lamps. Selective media inoculated with Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes were irradiated using UV-LEDs at 266, 270, 275, and 279 nm in the UVC spectrum at 0.1, 0.2, 0.5, and 0.7 mJ/cm², respectively. The radiation intensity of the UV-LEDs was about 4 μW/cm², and UV lamps were covered with polypropylene films to adjust the light intensity similar to those of UV-LEDs. In addition, we applied UV-LED to sliced cheese at doses of 1, 2, and 3 mJ/cm². Our results showed that inactivation rates after UV-LED treatment were significantly different (P < 0.05) from those of UV lamps at a similar intensity. On microbiological media, UV-LED treatments at 266 and 270 nm showed significantly different (P < 0.05) inactivation effects than other wavelength modules. For sliced cheeses, 4- to 5-log reductions occurred after treatment at 3 mJ/cm² for all three pathogens, with negligible generation of injured cells.     

Extreme ultraviolet radiation-sensitivity of respiratory adaptation in Saccharomyces cerevisiae cells during transition.

The respiratory adaptation process in both wild-type and UV-sensitive strains of $\text{Saccharomyces}\text{cerevisiae}$ was sensitive to small doses of UV-radiation (10 and 0.7 J/m², respectively). These doses of irradiation were ineffective in arresting induced synthesis of acid phosphatase and catalase. Exposure of the irradiated cells to visible light (370 – 800 nm) could completely restitute the impaired respiratory adaptation process. UV irradiation at these doses affected DNA and RNA synthesis in maturing mitochondria in both the yeast strains. The UV-induced block could however be eliminated by exposure of the cells to visible light. These results suggest that the lesion in the UV-induced block in the respiratory adaptation may be in the DNA of promitochondria.     

Brain responses to violet, blue, and green monochromatic light exposures in humans: prominent role of blue light and the brainstem

Background

Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established.

Methodology/Principal Findings

We exposed 15 participants to short duration (50 s) monochromatic violet (430 nm), blue (473 nm), and green (527 nm) light exposures of equal photon flux (10¹³ph/cm²/s) while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus.

Conclusion/Significance

These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function.     

Kjellmaniella crassifolia Miyabe (Gagome) Extract Modulates Intestinal and Systemic Immune Responses

Kjellmaniella crassifolia Miyabe (gagome) is a brown alga. Oral gagome administration (oral gagome) resulted in significant upregulation of IL-10 and IFNγ production by Peyer’s patch cells. To assess the adjuvant activity of oral gagome, treated mice were subcutaneously injected with ovalbumin (OVA). The production of cytokines from antigen (Ag)-specific T cells in draining lymph nodes (dLN) and their proliferative response were significantly increased as compared with the control group. These enhancements were associated with increased CD44^hiCD62L^? activated/memory T cells in dLN as well as upregulation of Ag-specific IgA level in luminal contents. No upregulation of cytokine production by dLN T cells was observed in dectin-1-deficient mice, suggesting that the effect of gagome on cytokine production is largely dependent on the dectin-1 pathway despite its composite constituents. Our findings indicate that gagome is an effective immunomodulator and a potent adjuvant for both the intestinal and the systemic immune response.