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https://www.readbyqxmd.com/read/27867253/drosophila-ezoana-uses-an-hour-glass-or-highly-damped-circadian-clock-for-measuring-night-length-and-inducing-diapause
#1
Koustubh M Vaze, Charlotte Helfrich-Förster
Insects inhabiting the temperate zones measure seasonal changes in day or night length to enter the overwintering diapause. Diapause induction occurs after the duration of the night exceeds a critical night length (CNL). Our understanding of the time measurement mechanisms is continuously evolving subsequent to Bünning's proposal that circadian systems play the clock role in photoperiodic time measurement (Bünning, 1936). Initially, the photoperiodic clocks were considered to be either based on circadian oscillators or on simple hour-glasses, depending on 'positive' or 'negative' responses in Nanda-Hamner and Bünsow experiments (Nanda & Hammer, 1958; Bünsow, 1960)...
December 2016: Physiological Entomology
https://www.readbyqxmd.com/read/27617484/periphyton-biofilms-influence-net-methylmercury-production-in-an-industrially-contaminated-system
#2
Todd A Olsen, Craig C Brandt, Scott C Brooks
Mercury (Hg) methylation and methylmercury (MMHg) demethylation activity of periphyton biofilms from the industrially contaminated East Fork Poplar Creek, Tennessee (EFPC) were measured during 2014-2016 using stable Hg isotopic rate assays. (201)Hg(II) and MM(202)Hg were added to intact periphyton samples in ambient streamwater and the formation of MM(201)Hg and loss of MM(202)Hg were monitored over time and used to calculate first-order rate potentials for methylation and demethylation. The influences of location, temperature/season, light exposure and biofilm structure on methylation and demethylation potentials were examined...
October 18, 2016: Environmental Science & Technology
https://www.readbyqxmd.com/read/27591521/decrease-in-light-dark-cycle-of-microalgal-cells-with-computational-fluid-dynamics-simulation-to-improve-microalgal-growth-in-a-raceway-pond
#3
Zongbo Yang, Jun Cheng, Qing Ye, Jianzhong Liu, Junhu Zhou, Kefa Cen
In this study, computational fluid dynamics (CFD) was used to systemically analyze the movement of algae in a vortex flow field produced by up-down chute baffles. The average cell light/dark (L/D) cycle period, vertical fluid velocity, fraction of time the algae was resides in light zone and the L/D cycle period were investigated under different paddlewheel speeds and microalgal concentrations. Results showed that the L/D cycle period decreased but the vertical fluid velocity increased when the up-down chute baffles were used...
November 2016: Bioresource Technology
https://www.readbyqxmd.com/read/27566940/the-transcription-factor-ap4-mediates-resolution-of-chronic-viral-infection-through-amplification-of-germinal-center-b-cell-responses
#4
Chun Chou, Daniel J Verbaro, Elena Tonc, Melanie Holmgren, Marina Cella, Marco Colonna, Deepta Bhattacharya, Takeshi Egawa
B cells diversify and affinity mature their antigen receptor repertoire in germinal centers (GCs). GC B cells receive help signals during transient interaction with T cells, yet it remains unknown how these transient T-B interactions in the light zone sustain the subsequent proliferative program of selected B cells that occurs in the anatomically distant dark zone. Here, we show that the transcription factor AP4 was required for sustained GC B cell proliferation and subsequent establishment of a diverse and protective antibody repertoire...
September 20, 2016: Immunity
https://www.readbyqxmd.com/read/27566830/il-17-superfamily-cytokines-modulate-normal-germinal-center-b-cell-migration
#5
Elisa Ferretti, Maurilio Ponzoni, Claudio Doglioni, Vito Pistoia
The germinal center (GC) is a dynamic structure formed by proliferating B cells in the follicles of secondary lymphoid organs during T cell-dependent antibody responses to exogenous antigens. GC is composed by a dark zone, enriched in proliferating centroblasts (CBs), and a light zone where CBs migrate and transform into centrocytes (CCs), a minority of which is selected to survive, undergoes Ig class-switch recombination, and differentiates into memory B cells or long-lived plasma cells. CBs express CXCR4 and are attracted to the dark zone by stromal cell-derived CXCL12, whereas CCs express CXCR5 and are recruited to the light zone along a gradient of CXCL13 produced by follicular dendritic cells (FDCs)...
August 26, 2016: Journal of Leukocyte Biology
https://www.readbyqxmd.com/read/27542977/ultrastructure-of-the-ovary-and-oogenesis-in-the-flatworm-prosthiostomum-siphunculus-polycladida-cotylea
#6
Mehrez Gammoudi, Willi Salvenmoser, Saïda Tekaya, Bernhard Egger
Based on light and electron microscopy observations, oogenesis in the cotylean polyclad Prosthiostomum siphunculus was investigated for the first time. The numerous ovarian follicles are dispersed essentially in the dorsal parenchyma. In the follicles, a ventral germinative zone with undifferentiated germs cells of different sizes and a dorsal growth zone with larger growing and abortive oocytes are present. The oogenesis could be subdivided into four stages: (1) Oogonia with a dark nucleus and a dark, ribosome-rich cytoplasm...
November 2016: Cell Biology International
https://www.readbyqxmd.com/read/27465674/early-ccr6-expression-on-b-cells-modulates-germinal-centre-kinetics-and-efficient-antibody-responses
#7
Dorothea Reimer, Adrian Y S Lee, Jennifer Bannan, Phillip Fromm, Ervin E Kara, Iain Comerford, Shaun McColl, Florian Wiede, Dirk Mielenz, Heinrich Körner
The CC-chemokine receptor 6 (CCR6) can be detected on naïve and activated B cells. Counterintuitively, its absence accelerates the appearance of germinal centres (GC) and increases the production of low-affinity antibodies. The detailed mechanism of CCR6 function during the humoral response has remained elusive but previously we identified a distinct CCR6(high) B cell population in vivo early after antigenic challenge. In this study, we defined this population specifically as early, activated pre-GC B cells...
July 28, 2016: Immunology and Cell Biology
https://www.readbyqxmd.com/read/27448584/yy1-regulates-the-germinal-center-reaction-by-inhibiting-apoptosis
#8
Sally E Trabucco, Rachel M Gerstein, Hong Zhang
The germinal center (GC) reaction produces high-affinity Abs for a robust adaptive immune response. When dysregulated, the same processes cause GC B cells to become susceptible to lymphomagenesis. It is important to understand how the GC reaction is regulated. In this study, we show that transcription factor YY1 is required to maintain a robust GC reaction in mice. Selective ablation of YY1 significantly decreased in the frequency and number of GC B cells during the GC reaction. This decrease of GC B cells was accompanied by increased apoptosis in these cells...
September 1, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/27409480/outer-retinal-changes-including-the-ellipsoid-zone-band-in-usher-syndrome-1b-due-to-myo7a-mutations
#9
Alexander Sumaroka, Rodrigo Matsui, Artur V Cideciyan, David B McGuigan, Rebecca Sheplock, Sharon B Schwartz, Samuel G Jacobson
PURPOSE: To study transition zones from normal to abnormal retina in Usher syndrome IB (USH1B) caused by myosin 7A (MYO7A) mutations. METHODS: Optical coherence tomography (OCT) scattering layers in outer retina were segmented in patients (n = 16, ages 2-42; eight patients had serial data, average interval 4.5 years) to quantify outer nuclear layer (ONL) and outer segments (OS) as well as the locus of EZ (ellipsoid zone) edge and its extent from the fovea. Static perimetry was measured under dark-adapted (DA) and light-adapted (LA) conditions...
July 1, 2016: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/27376463/visible-light-photo-catalytic-inactivation-of-bacteria-and-photo-degradation-of-methylene-blue-with-ag-tio2-nanocomposite-prepared-by-a-novel-method
#10
Kamran Tahir, Aftab Ahmad, Baoshan Li, Sadia Nazir, Arif Ullah Khan, Tabassum Nasir, Zia Ul Haq Khan, Rubina Naz, Muslim Raza
Water purification is one of the worldwide problem and most of the conventional methods are associated with a number of drawbacks. Therefore it is the need of the day to develop new methods and materials to overcome the problem of water purification. In this research work we present a simple and green approach to synthesize silver decorated titanium dioxide (Ag/TiO2) nanocomposite with an efficient photo catalytic activities. Phytochemicals of the Cestrum nocturnum leaf extract were used to synthesize silver nanoparticles (AgNPs), Titanium dioxide (TiO2) and Ag/TiO2 nanocomposite...
September 2016: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/27375593/regulation-of-intertidal-microphytobenthos-photosynthesis-over-a-diel-emersion-period-is-strongly-affected-by-diatom-migration-patterns
#11
Paulo Cartaxana, Sónia Cruz, Carla Gameiro, Michael Kühl
Changes in biomass and photosynthesis of a diatom-dominated microphytobenthos (MPB) intertidal community were studied over a diel emersion period using a combination of O2 and scalar irradiance microprofiling, variable chlorophyll (Chl) fluorescence, and pigment analysis. The MPB biomass in the photic zone (0-0.5 mm) of the sediment exposed to low irradiance (150 μmol photons m(-2) s(-1)) showed a >2-fold increase during the first hours of the emersion period, reaching >0.2 mg Chl a cm(-3). Concentrations of Chl a started to decrease half-way through the emersion period, almost 2 h before tidal inundation...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27335398/functional-roles-of-complexin3-and-complexin4-at-mouse-photoreceptor-ribbon-synapses
#12
Norbert Babai, Anna Sendelbeck, Hanna Regus-Leidig, Michaela Fuchs, Jasmin Mertins, Kerstin Reim, Nils Brose, Andreas Feigenspan, Johann Helmut Brandstätter
UNLABELLED: Complexins (Cplxs) are SNARE complex regulators controlling the speed and Ca(2+) sensitivity of SNARE-mediated synaptic vesicle fusion. We have shown previously that photoreceptor ribbon synapses in mouse retina are equipped with Cplx3 and Cplx4 and that lack of both Cplxs perturbs photoreceptor ribbon synaptic function; however, Cplx3/4 function in photoreceptor synaptic transmission remained elusive. To investigate Cplx3/4 function in photoreceptor ribbon synapses, voltage-clamp recordings from postsynaptic horizontal cells were performed in horizontal slice preparations of Cplx3/4 wild-type (WT) and Cplx3/4 double knock-out (DKO) mice...
June 22, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27225586/dynamic-spatial-patterns-of-leaf-traits-affect-total-respiration-on-the-crown-scale
#13
Xiaolin Wang, Hongxuan Zhou, Fengsen Han, Yuanzheng Li, Dan Hu
Temporal and spatial variations of leaf traits caused conflicting conclusions and great estimating errors of total carbon budget on crown scales. However, there is no effective method to quantitatively describe and study heterogeneous patterns of crowns yet. In this study, dynamic spatial patterns of typical ecological factors on crown scales were investigated during two sky conditions, and CEZs (crown ecological zones) method was developed for spatial crown zoning, within which leaf traits were statistically unchanged...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27221157/nutrition-and-the-circadian-system
#14
Gregory D M Potter, Janet E Cade, Peter J Grant, Laura J Hardie
The human circadian system anticipates and adapts to daily environmental changes to optimise behaviour according to time of day and temporally partitions incompatible physiological processes. At the helm of this system is a master clock in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. The SCN are primarily synchronised to the 24-h day by the light/dark cycle; however, feeding/fasting cycles are the primary time cues for clocks in peripheral tissues. Aligning feeding/fasting cycles with clock-regulated metabolic changes optimises metabolism, and studies of other animals suggest that feeding at inappropriate times disrupts circadian system organisation, and thereby contributes to adverse metabolic consequences and chronic disease development...
August 2016: British Journal of Nutrition
https://www.readbyqxmd.com/read/27199893/rfrp-neurons-the-doorway-to-understanding-seasonal-reproduction-in-mammals
#15
REVIEW
Jo B Henningsen, François Gauer, Valérie Simonneaux
Seasonal control of reproduction is critical for the perpetuation of species living in temperate zones that display major changes in climatic environment and availability of food resources. In mammals, seasonal cues are mainly provided by the annual change in the 24-h light/dark ratio (i.e., photoperiod), which is translated into the nocturnal production of the pineal hormone melatonin. The annual rhythm in this melatonin signal acts as a synchronizer ensuring that breeding occurs when environmental conditions favor survival of the offspring...
2016: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/27166359/fbxo11-inactivation-leads-to-abnormal-germinal-center-formation-and-lymphoproliferative-disease
#16
Christof Schneider, Ning Kon, Letizia Amadori, Qiong Shen, Friederike H Schwartz, Benjamin Tischler, Marion Bossennec, David Dominguez-Sola, Govind Bhagat, Wei Gu, Katia Basso, Riccardo Dalla-Favera
The BCL6 proto-oncogene encodes a transcriptional repressor that is required for the germinal center (GC) reaction and is implicated in lymphomagenesis. BCL6 protein stability is regulated by F-box protein 11 (FBXO11)-mediated ubiquitination and degradation, which is impaired in ∼6% of diffuse large B-cell lymphomas that carry inactivating genetic alterations targeting the FBXO11 gene. In order to investigate the role of FBXO11 in vivo, we analyzed GC-specific FBXO11 knockout mice. FBXO11 reduction or loss led to an increased number of GC B cells, to an altered ratio of GC dark zone to light zone cells, and to higher levels of BCL6 protein in GC B cells...
August 4, 2016: Blood
https://www.readbyqxmd.com/read/27036650/nociceptin-receptor-antagonist-sb-612111-decreases-high-fat-diet-binge-eating
#17
J Andrew Hardaway, Jennifer Jensen, Michelle Kim, Christopher M Mazzone, Jonathan A Sugam, Jeffrey F Diberto, Emily G Lowery-Gionta, Lara S Hwa, Kristen E Pleil, Cynthia M Bulik, Thomas L Kash
Binge eating is a dysregulated form of feeding behavior that occurs in multiple eating disorders including binge-eating disorder, the most common eating disorder. Feeding is a complex behavioral program supported through the function of multiple brain regions and influenced by a diverse array of receptor signaling pathways. Previous studies have shown the overexpression of the opioid neuropeptide nociceptin (orphanin FQ, N/OFQ) can induce hyperphagia, but the role of endogenous nociceptin receptor (NOP) in naturally occurring palatability-induced hyperphagia is unknown...
July 1, 2016: Behavioural Brain Research
https://www.readbyqxmd.com/read/27031879/non-parametric-photic-entrainment-of-djungarian-hamsters-with-different-rhythmic-phenotypes
#18
Konrad Schöttner, Jane Hauer, Dietmar Weinert
To investigate the role of non-parametric light effects in entrainment, Djungarian hamsters of two different circadian phenotypes were exposed to skeleton photoperiods, or to light pulses at different circadian times, to compile phase response curves (PRCs). Wild-type (WT) hamsters show daily rhythms of locomotor activity in accord with the ambient light/dark conditions, with activity onset and offset strongly coupled to light-off and light-on, respectively. Hamsters of the delayed activity onset (DAO) phenotype, in contrast, progressively delay their activity onset, whereas activity offset remains coupled to light-on...
2016: Chronobiology International
https://www.readbyqxmd.com/read/27007146/rewriting-the-rules-governing-high-intensity-interactions-of-light-with-matter
#19
Alex B Borisov, John C McCorkindale, Sankar Poopalasingam, James W Longworth, Peter Simon, Sándor Szatmári, Charles K Rhodes
The trajectory of discovery associated with the study of high-intensity nonlinear radiative interactions with matter and corresponding nonlinear modes of electromagnetic propagation through material that have been conducted over the last 50 years can be presented as a landscape in the intensity/quantum energy [I-ħω] plane. Based on an extensive series of experimental and theoretical findings, a universal zone of anomalous enhanced electromagnetic coupling, designated as the fundamental nonlinear domain, can be defined...
April 2016: Reports on Progress in Physics
https://www.readbyqxmd.com/read/26989201/gna13-loss-in-germinal-center-b-cells-leads-to-impaired-apoptosis-and-promotes-lymphoma-in-vivo
#20
Jane A Healy, Adrienne Nugent, Rachel E Rempel, Andrea B Moffitt, Nicholas S Davis, Xiaoyu Jiang, Jennifer R Shingleton, Jenny Zhang, Cassandra Love, Jyotishka Datta, Matthew E McKinney, Tiffany J Tzeng, Nina Wettschureck, Stefan Offermanns, Katelyn A Walzer, Jen-Tsan Chi, Suhail A K Rasheed, Patrick J Casey, Izidore S Lossos, Sandeep S Dave
GNA13 is the most frequently mutated gene in germinal center (GC)-derived B-cell lymphomas, including nearly a quarter of Burkitt lymphoma and GC-derived diffuse large B-cell lymphoma. These mutations occur in a pattern consistent with loss of function. We have modeled the GNA13-deficient state exclusively in GC B cells by crossing the Gna13 conditional knockout mouse strain with the GC-specific AID-Cre transgenic strain. AID-Cre(+) GNA13-deficient mice demonstrate disordered GC architecture and dark zone/light zone distribution in vivo, and demonstrate altered migration behavior, decreased levels of filamentous actin, and attenuated RhoA activity in vitro...
June 2, 2016: Blood
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