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Roger Duarte de Melo, Daniel Acosta-Avalos
'Candidatus Magnetoglobus multicellularis' is the most studied multicellular magnetotactic prokaryote. It presents a light-dependent photokinesis: green light decreases the translation velocity whereas red light increases it, in comparison to blue and white light. The present article shows that radio-frequency electromagnetic fields cancel the light effect on photokinesis. The frequency to cancel the light effect corresponds to the Zeeman resonance frequency (DC magnetic field of 4 Oe and radio-frequency of 11...
October 20, 2016: Antonie Van Leeuwenhoek
Joseph F O'Grady, Laura S Hoelters, Martin T Swain, David C Wilcockson
BACKGROUND: Talitrus saltator is an amphipod crustacean that inhabits the supralittoral zone on sandy beaches in the Northeast Atlantic and Mediterranean. T. saltator exhibits endogenous locomotor activity rhythms and time-compensated sun and moon orientation, both of which necessitate at least one chronometric mechanism. Whilst their behaviour is well studied, currently there are no descriptions of the underlying molecular components of a biological clock in this animal, and very few in other crustacean species...
2016: PeerJ
Alberto Ugolini, Laura S Hoelters, Alice Ciofini, Vittorio Pasquali, David C Wilcockson
Animals that use astronomical cues to orientate must make continuous adjustment to account for temporal changes in azimuth caused by Earth's rotation. For example, the Monarch butterfly possesses a time-compensated sun compass dependent upon a circadian clock in the antennae. The amphipod Talitrus saltator possesses both a sun compass and a moon compass. We reasoned that the time-compensated compass mechanism that enables solar orientation of T. saltator is located in the antennae, as is the case for Monarch butterflies...
October 19, 2016: Scientific Reports
Andrea von Zadow, Elisabeth Ignatz, Richard Pokorny, Lars-Oliver Essen, Gabriele Klug
Photolyases are efficient DNA repair enzymes that specifically repair either cyclobutane pyrimidine dimers (CPD) or (6-4) photoproducts in a light-dependent cleavage reaction. The closely related classical cryptochrome blue light photoreceptors do not repair DNA lesions, instead they are involved in regulatory processes. CryB of Rhodobacter sphaeroides was until now described as a cryptochrome that affects light-dependent and singlet oxygen-dependent gene expression and is unusual in terms of its cofactor composition...
October 14, 2016: FEBS Journal
Na Liu, Eric Erquan Zhang
The core circadian oscillator in mammals is composed of transcription/translation feedback loop, in which cryptochrome (CRY) proteins play critical roles as repressors of their own gene expression. Although post-translational modifications, such as phosphorylation of CRY1, are crucial for circadian rhythm, little is known about how phosphorylated CRY1 contributes to the molecular clockwork. To address this, we created a series of CRY1 mutants with single amino acid substitutions at potential phosphorylation sites and performed a cell-based, phenotype-rescuing screen to identify mutants with aberrant rhythmicity in CRY-deficient cells...
2016: Frontiers in Neurology
Leena Kovanen, Kati Donner, Mari Kaunisto, Timo Partonen
BACKGROUND: Dysfunctions in the intrinsic clocks are suggested in patients with depressive disorders. The cryptochrome circadian clocks 1 and 2 (CRY1 and CRY2) proteins modulate circadian rhythms in a cell and influence emotional reactions and mood in an individual. The protein kinase C delta binding protein (PRKCDBP, or CAVIN3), similar to the serum deprivation response protein (SDPR, or CAVIN2), reduces metabolic stability of the PER2-CRY2 transcription factor complex that plays a role in the circadian rhythm synchronization...
September 28, 2016: Journal of Affective Disorders
Fiona E Belbin, Zeenat B Noordally, Sarah J Wetherill, Kelly A Atkins, Keara A Franklin, Antony N Dodd
We investigated the signalling pathways that regulate chloroplast transcription in response to environmental signals. One mechanism controlling plastid transcription involves nuclear-encoded sigma subunits of plastid-encoded plastid RNA polymerase. Transcripts encoding the sigma factor SIG5 are regulated by light and the circadian clock. However, the extent to which a chloroplast target of SIG5 is regulated by light-induced changes in SIG5 expression is unknown. Moreover, the photoreceptor signalling pathways underlying the circadian regulation of chloroplast transcription by SIG5 are unidentified...
September 15, 2016: New Phytologist
Vishnu V Krishnamurthy, John S Khamo, Wenyan Mei, Aurora J Turgeon, Humza M Ashraf, Payel Mondal, Dil B Patel, Noah Risner, Ellen E Cho, Jing Yang, Kai Zhang
A limited number of signaling pathways are repeatedly used to regulate a wide variety of processes during development and differentiation. Lack of tools to dynamically manipulate signaling pathways in space and time has been a major technical challenge for biologists. Optogenetic techniques, which utilize light to control protein functions in a reversible fashion, hold promise in modulating intracellular signaling networks with high spatial and temporal resolution. Applications of the optogenetics in multicellular organisms, however, have not been widely reported...
October 3, 2016: Development
Silke von Horsten, Simon Straß, Nils Hellwig, Verena Gruth, Ramona Klasen, Andreas Mielcarek, Uwe Linne, Nina Morgner, Lars-Oliver Essen
Organisms developed different photoreceptors to be able to adapt to changing environmental light conditions. Phytochromes are red/far-red (r/fr) photochromic photoreceptors that belong to the classical photoreceptors along with cryptochromes and phototropins. They convert absorbed light into a biological signal by switching between two states in a light-dependent manner therefore enabling the light control downstream signalling. Their Pfr conformation is the biological active form in plants, but until now only a structure of the ground state (Pr) was solved...
October 3, 2016: Scientific Reports
Yi-Ying Chiou, Yanyan Yang, Naim Rashid, Rui Ye, Christopher P Selby, Aziz Sancar
The mammalian circadian clock is based on a transcription-translation feedback loop (TTFL) consolidated by secondary loops. In the primary TTFL, the circadian locomotor output cycles kaput (CLOCK)-brain and muscle Arnt-like protein-1 (BMAL1) heterodimer acts as the transcriptional activator, and Cryptochrome (CRY) and Period (PER) proteins function as repressors. PER represses by displacing CLOCK-BMAL1 from promoters in a CRY-dependent manner. Interestingly, genes with complex promoters may either be repressed or de-repressed by PER, depending on the particular promoter regulatory elements...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
Dimitris Petroutsos, Ryutaro Tokutsu, Shinichiro Maruyama, Serena Flori, Andre Greiner, Leonardo Magneschi, Loic Cusant, Tilman Kottke, Maria Mittag, Peter Hegemann, Giovanni Finazzi, Jun Minagawa
In plants and algae, light serves both as the energy source for photosynthesis and a biological signal that triggers cellular responses via specific sensory photoreceptors. Red light is perceived by bilin-containing phytochromes and blue light by the flavin-containing cryptochromes and/or phototropins (PHOTs), the latter containing two photosensory light, oxygen, or voltage (LOV) domains. Photoperception spans several orders of light intensity, ranging from far below the threshold for photosynthesis to values beyond the capacity of photosynthetic CO2 assimilation...
September 14, 2016: Nature
Daisuke Ono, Sato Honma, Ken-Ichi Honma
The suprachiasmatic nucleus (SCN) is the site of the master circadian clock in mammals. The SCN neural network plays a critical role in expressing the tissue-level circadian rhythm. Previously, we demonstrated postnatal changes in the SCN network in mice, in which the clock gene products CRYPTOCHROMES (CRYs) are involved. Here, we show that vasoactive intestinal polypeptide (VIP) signaling is essential for the tissue-level circadian PER2::LUC rhythm in the neonatal SCN of CRY double-deficient mice (Cry1,2 (-/-) )...
September 2016: Science Advances
Zuoqiong Zhou, Xiyang Peng, Jianbin Chen, Xiushan Wu, Yuequn Wang, Yunhan Hong
Magnetoreception is essential for magnetic orientation in animal migration. The molecular basis for magnetoreception has recently been elucidated in fruitfly as complexes between the magnetic receptor magnetoreceptor (MagR) and its ligand cryptochrome (Cry). MagR and Cry are present in the animal kingdom. However, it is unknown whether they perform a conserved role in diverse animals. Here we report the identification and expression of zebrafish MagR and Cry homologs towards understanding their roles in lower vertebrates...
September 6, 2016: Science China. Life Sciences
Aya Shimomura, Ayumi Naka, Nobuyuki Miyazaki, Sayaka Moriuchi, Susumu Arima, Shusei Sato, Hideki Hirakawa, Makoto Hayashi, Maskit Maymon, Ann M Hirsch, Akihiro Suzuki
In many legumes, roots that are exposed to light do not form nodules. Here, we report that blue light inhibits nodulation in Lotus japonicus roots inoculated with Mesorhizobium loti. Using RNA interference, we suppressed the expression of phototropin and cryptochrome genes in L. japonicus hairy roots. Under blue light, plants transformed with an empty vector did not develop nodules, whereas plants exhibiting suppressed expression of cry1 and cry2 genes formed nodules. We also measured rhizobial growth to investigate whether the inhibition of nodulation could be caused by a reduced population of rhizobia in response to light...
September 9, 2016: Molecular Plant-microbe Interactions: MPMI
Andrew P Patton, Johanna E Chesham, Michael H Hastings
UNLABELLED: The suprachiasmatic nucleus (SCN) is the master circadian oscillator encoding time-of-day information. SCN timekeeping is sustained by a cell-autonomous transcriptional-translational feedback loop, whereby expression of the Period and Cryptochrome genes is negatively regulated by their protein products. This loop in turn drives circadian oscillations in gene expression that direct SCN electrical activity and thence behavior. The robustness of SCN timekeeping is further enhanced by interneuronal, circuit-level coupling...
September 7, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Chunxiao Xu, Yang Yu, Yuxia Zhang, Yue Li, Shufeng Wei
We previously found that flowering of Arabidopsis was suppressed by near-null magnetic field, which was related to the modification of cryptochrome. To disclose the physiological mechanism of this effect, we detected gibberellin (GA) levels and expressions of GA biosynthetic and signaling genes in wild type Arabidopsis plants and cryptochrome double mutant, cry1/cry2, grown in near-null magnetic field. We found that levels of GA4 , GA9 , GA34 , and GA51 in wild type plants in near-null magnetic field were significantly decreased compared with local geomagnetic field controls...
September 6, 2016: Bioelectromagnetics
Emrys W Evans, Daniel R Kattnig, Kevin B Henbest, P J Hore, Stuart R Mackenzie, Christiane R Timmel
Even though the interaction of a <1 mT magnetic field with an electron spin is less than a millionth of the thermal energy at room temperature (kBT), it still can have a profound effect on the quantum yields of radical pair reactions. We present a study of the effects of sub-millitesla magnetic fields on the photoreaction of flavin mononucleotide with ascorbic acid. Direct control of the reaction pathway is achieved by varying the rate of electron transfer from ascorbic acid to the photo-excited flavin. At pH 7...
August 28, 2016: Journal of Chemical Physics
Vladimir D Kreslavski, Anatoly A Kosobryukhov, Franz-Josef Schmitt, Galina A Semenova, Galina N Shirshikova, Aleksandra Yu Khudyakova, Suleyman I Allakhverdiev
The reduced content of photoreceptors, such as phytochromes, can decrease the efficiency of photosynthesis and activity of the photosystem II (PSII). For the confirmation of this hypothesis, the effect of deficiency in both phytochromes (Phy) A and B (double mutant, DM) in 7-27-day-old Arabidopsis thaliana plants on the photosynthetic activity was studied in absence and presence of UV-A radiation as a stress factor. The DM with reduced content of apoproteins of PhyA and PhyB and wild type (WT) plants with were grown in white and red light (WL and RL, respectively) of high (130 μmol quanta m(-2) s(-1)) and low (40 μmol quanta m(-2) s(-1)) intensity...
September 1, 2016: Protoplasma
Matthias Schlichting, Pamela Menegazzi, Katharine R Lelito, Zepeng Yao, Edgar Buhl, Elena Dalla Benetta, Andrew Bahle, Jennifer Denike, James John Hodge, Charlotte Helfrich-Förster, Orie Thomas Shafer
UNLABELLED: A sensitivity of the circadian clock to light/dark cycles ensures that biological rhythms maintain optimal phase relationships with the external day. In animals, the circadian clock neuron network (CCNN) driving sleep/activity rhythms receives light input from multiple photoreceptors, but how these photoreceptors modulate CCNN components is not well understood. Here we show that the Hofbauer-Buchner eyelets differentially modulate two classes of ventral lateral neurons (LNvs) within the Drosophila CCNN...
August 31, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Abir Ganguly, Craig C Manahan, Deniz Top, Estella F Yee, Changfan Lin, Michael W Young, Walter Thiel, Brian R Crane
Cryptochrome (CRY) is the principal light sensor of the insect circadian clock. Photoreduction of the Drosophila CRY (dCRY) flavin cofactor to the anionic semiquinone (ASQ) restructures a C-terminal tail helix (CTT) that otherwise inhibits interactions with targets that include the clock protein Timeless (TIM). All-atom molecular dynamics (MD) simulations indicate that flavin reduction destabilizes the CTT, which undergoes large-scale conformational changes (the CTT release) on short (25 ns) timescales. The CTT release correlates with the conformation and protonation state of conserved His378, which resides between the CTT and the flavin cofactor...
September 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
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