Dark zone light zone

The rotation of the Earth around its own axis and around the sun determines the characteristics of the light/dark cycle, the most stable and ancient 24 h temporal cue for all organisms. Due to the tilt in the earth's axis in relation to the plane of the earth's orbit around the sun, sunlight reaches the Earth differentially depending on the latitude. The timing of circadian rhythms varies among individuals of a given population and biological and environmental factors underlie this variability. In the present study, we tested the hypothesis that latitude is associated to the regulation of circadian rhythm in humans...

Fabry disease is an X-linked inherited lysosomal storage disorder with intracellular accumulation of globotriaosylceramide (Gb3) due to α-galactosidase A (α-Gal A) deficiency. Fabry patients frequently report of anxiety, depression, and impaired cognitive function. We characterized affective and cognitive phenotype of male mice with α-Gal A deficiency (Fabry KO) and compared results with those of age-matched male wildtype (WT) littermates. Young (3 months) and old (≥ 18 months) mice were tested in the naïve state and after i...

Traveling across several time zones requires a fast adjustment of the circadian system and the differential adjustment speeds of organs and systems results in what is commonly referred as jet lag. During this transitory state of circadian disruption, individuals feel discomfort, appetite loss, fatigue, disturbed sleep and deficient performance of multiple tasks. We have demonstrated that after a 6-h phase advance of the light-dark cycle (LD) scheduled food in phase with the new night onset can speed up re-entrainment...

During antibody affinity maturation, germinal center (GC) B cells cycle between affinity-driven selection in the light zone (LZ) and proliferation and somatic hypermutation in the dark zone (DZ). Although selection of GC B cells is triggered by antigen-dependent signals delivered in the LZ, DZ proliferation occurs in the absence of such signals. We show that positive selection triggered by T cell help activates the mechanistic target of rapamycin complex 1 (mTORC1), which promotes the anabolic program that supports DZ proliferation...

Glyoxalase 1 (Glo1) is the first enzyme involved in glutathione-dependent detoxification of methylglyoxal, eventually generating d-lactate by the second enzyme glyoxalase 2 (Glo2). An accumulation of intracellular glyoxal and methylglyoxal leads to protein malfunction and mutation via formation of the advanced glycation end products (AGEs). Studies on mouse behavior suggest that methylglyoxal has anxiolytic properties. In this report, we generated and characterized a mouse knockout for Glo1. The knockout mice were viable without a pronounced phenotypic defect...

Silver loaded and Er(3+)/Yb(3+) doped BaMoO4 octahedron microcrystals were fabricated by microwave hydrothermal process. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDS), and Ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS). The antibacterial application of samples were investigated by visible light irradiation and disk-diffusion method towards representative Gram-negative pathogen (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive pathogen (methicillin resistant Staphylococcus aureus)...

While the biogeochemical forces influencing the weathering of spilled oil have been investigated for decades, the environmental fate and effects of "oxyhydrocarbons" in sand patties deposited on beaches are not well-known. We collected sand patties deposited in the swash zone on Gulf of Mexico beaches following the Deepwater Horizon oil spill. When sand patties were exposed to simulated sunlight, a larger concentration of dissolved organic carbon was leached into seawater than the corresponding dark controls...

Coral reefs are amongst the most diverse ecosystems on Earth where complex inter-specific interactions are ubiquitous. An example of such interactions is the mutualistic relationship between damselfishes and branching corals in the Northern Red Sea, where the fish use corals as shelter and provide them with nutrients, enhance the flow between their branches, and protect them from predators. By enhancing the flow between the coral branches, the fish ventilate the coral's inner zone, mitigating hypoxic conditions that otherwise develop within that zone during the night...

The necrotrophic pathogen Rhizoctonia solani is one of the most economically important soil-borne pathogens of crop plants. Isolates of R. solani AG1-IB are the major pathogens responsible for bottom-rot of lettuce (Lactuca sativa L.) and are also responsible for diseases in other plant species. Currently, there is lack of information regarding the molecular responses in R. solani during the pathogenic interaction between the necrotrophic soil-borne pathogen and its host plant. The genome of R. solani AG1-IB (isolate 7/3/14) was recently established to obtain insights into its putative pathogenicity determinants...

Photodynamic Inactivation (PDI) is based on the use of a photosensitizer (PS) and light that results mainly in the production of reactive oxygen species, aiming to produce microorganism cell death. PS incubation time and light dose are key protocol parameters that influence PDI response; the correct choice of them can increase the efficiency of inactivation. The results of this study show that a minor change in the PDI protocol, namely light-driven incubation leads to a higher photosensitizer and more uniform cell uptake inside the irradiated zone...

Animals living in the intertidal zone are exposed to prominent temperature changes. To cope with the energetic demands of environmental thermal challenges, ectotherms rely mainly on behavioral responses, which may change depending on the time of the day and seasonally. Here, we analyze how temperature shapes crabs' behavior at 2 different times of the year and show that a transition from constant cold (13.5°C) to constant warm (17.5°C) water temperature leads to increased locomotor activity levels throughout the day in fiddler crabs (Uca pugilator) collected during the summer...

A simple, green method is described for the synthesis of Gold (Au) nanoparticles (NPs) using Cotoneaster horizontalis extract as a phyto-reducer and capping agent with superior photo inhibition activity against Pseudomonas aeruginosa. Different from the other methods used elevated temperatures for nanoparticles synthesis, the novelty of our method lies in its energy saving process and fast synthesis rates (~5min for AuNPs), and its potential to tune the nanoparticles size and afterward their catalytic activity...

The formation of metal nanoparticles is one of the most vast and intensifying research areas in favor of prospective applications for the advancement of new technologies. It is a well-founded, significant feature of green chemistry that making marvelous interconnection between nano-biotechnology and microbial biotechnology. In the present research, the aqueous extract of medicinally important plant Coptis Chinensis (in Chinese called "gold thread") was applied for the synthesis of gold nanoparticles (Au-NPs)...

Teleost fish continues to grow their eyes throughout life with the body size. In Astatotilapia burtoni, the fish retina increases by adding new retinal cells at the ciliary marginal zone (CMZ) and in the outer nuclear layer (ONL). Cell proliferation at both sites exhibits a daily rhythm in number of dividing cells. To understand how this diurnal rhythm of new cell production is controlled in retinal progenitor cells, we studied the transcription pattern of clock genes in retina, including clock1a, clock1b, bmal1a (brain and muscle ARNT-Like), and per1b (period1b)...

Visual abilities of the honey bee have been studied for more than 100 years, recently revealing unexpectedly sophisticated cognitive skills rivalling those of vertebrates. However, the physiological limits of the honey bee eye have been largely unaddressed and only studied in an unnatural, dark state. Using a bright display and intracellular recordings, we here systematically investigated the angular sensitivity across the light adapted eye of honey bee foragers. Angular sensitivity is a measure of photoreceptor receptive field size and thus small values indicate higher visual acuity...

When light emitters are being placed in close proximity to a plasmonic system, not only the emission but also the excitation can be strongly enhanced and both yield the surface plasmon polariton (SPP) mediated fluorescence enhancement. Here, we combine the rate equation model and coupled mode theory to formulate the excitation rate of light emitters located on a periodic metallic array. The rate is expressed in terms of quantities that can be measured by angle- and polarization-resolved reflectivity and photoluminescence spectroscopy...

Plasma cells (PCs) derived from germinal centers (GCs) secrete the high-affinity antibodies required for long-term serological immunity. Nevertheless, the process whereby GC B cells differentiate into PCs is uncharacterized, and the mechanism underlying the selective PC differentiation of only high-affinity GC B cells remains unknown. In this study, we show that differentiation into PCs is induced among a discrete subset of high-affinity B cells residing within the light zone of the GC. Initiation of differentiation required signals delivered upon engagement with intact antigen...

Germinal center (GC) B cells cycle between two states, the light zone (LZ) and the dark zone (DZ), and in the latter they proliferate and hypermutate their immunoglobulin genes. How this functional transition takes place is still controversial. In this study, we demonstrate that ablation of Foxo1 after GC development led to the loss of the DZ GC B cells and disruption of the GC architecture, which is consistent with recent studies. Mechanistically, even upon provision of adequate T cell help, Foxo1-deficient GC B cells showed less proliferative expansion than controls...

The pesticide mancozeb (mz) is recognized as a potent inducer of oxidative stress due to its ability to catalyze the production of reactive oxygen species plus inhibiting mitochondrial respiration thus becoming an environmental risk for neurodegenerative diseases. Despite numerous toxicological studies on mz have been directed to mammals, attention on marine fish is still lacking. Thus, it was our intention to evaluate neurobehavioral activities of ornate wrasses (Thalassoma pavo) exposed to 0.2mg/l of mz after a preliminary screening test (0...

Laboratories and vivariums typically are maintained at ambient temperatures of 20 to 24 °C, leading to cold stress in mice. When mice are inactive and sleeping during the light phase, their zone of thermoneutrality associated with a basal metabolic rate is 30 to 32 °C. If given a choice, mice will use thermoregulatory behavior to seek out thermoneutral temperatures during the light phase. The cold stress of a vivarium can be problematic to researchers requiring an animal model that is not stressed metabolically...