Microphotometric, ultrastructural, and electrophysiological analyses of light-dependent processes on visual receptors in white-eyed wild-type and norpA (noreceptor potential) mutant Drosophila

1990 ◽  
Vol 5 (5) ◽  
pp. 429-439 ◽  
Author(s):  
Gregory M. Zinkl ◽  
Linnette Maier ◽  
Kent Studer ◽  
Randall Sapp ◽  
De-Mao Chen ◽  
...  
Keyword(s):  
Visual Pigment ◽  
Lucifer Yellow ◽  
Time Of Day ◽  
Constant Light ◽  
Dark Cycle ◽  
Uptake Mechanism ◽  
Higher Temperature ◽  
Dependent Processes ◽  
Phototransduction Cascade

AbstractWe examined a white-eyed strain of the norpA mutant (norpA;cn bw) and white (w)norpA+ controls using microspectrophotometry (MSP), electron microscopy (EM), and electroretinography (ERG). These studies revealed that light mediates receptor demise in norpA even though norpA lacks phototransduction. Rhodopsin and the rhabdomere which houses it decrease with increasing age in norpA but not in w with rearing on a 12 h light/12-h dark cycle or in constant light. At higher temperature in norpA;cn bw and w reared in constant light, visual pigment decreases, rhabdomeres diminish, and cells die. Importantly, dark rearing blocked visual pigment loss in norpA;cn bw; the M-potential, an ERG reflection of visual pigment level, corroborated this finding. MSP showed that norpA's visual pigment loss was not due to acute loss of metarhodopsin, rhodopsin's photoproduct. NorpA blocks certain processes expected to be light elicited. The alteration of visual pigment as a function of time of day, present in w controls, is absent in white-eyed norpA, suggesting that light-induced depolarization may be necessary to entrain the rhythm. Microspectrofluorometry using the fluorescent dye, Lucifer yellow, suggested that norpA lacks a light-induced uptake mechanism; using control flies, we determined the stimulus parameters required for uptake in vivo. An attempt to “cure” norpA;cn bw by replacement “therapy” using phospholipase C, missing in norpA's phototransduction cascade, was largely unsuccessful.

Uptake, Internalization and Degradation of the Novel Plasminogen Activator Reteplase (BM 06.022) in the Rat

1995 ◽  
Vol 74 (06) ◽  
pp. 1501-1510 ◽  
Author(s):  
J Kuiper ◽  
H van de Bilt ◽  
U Martin ◽  
Th J C van Berkel
Keyword(s):  
Plasminogen Activator ◽  
Liver Cells ◽  
The Novel ◽  
Uptake Mechanism ◽  
Liver Uptake ◽  
Lysosomal Compartment ◽  
Β Phase ◽  
Α Phase ◽  
Parenchymal Liver

SummaryThe catabolism of the novel plasminogen activator reteplase (BM 06.022) was described. For this purpose BM 06.022 was radiolabelled with l25I or with the accumulating label l25I-tyramine cellobiose (l25I-TC).BM 06.022 was injected at a pharmacological dose of 380 μg/kg b.w. and it was cleared from the plasma in a biphasic manner with a half-life of about 1 min in the α-phase and t1/2of 20-28 min in the β-phase. 28% and 72% of the injected dose was cleared in the α-phase and β-phase, respectively. Initially liver, kidneys, skin, bones, lungs, spleen, and muscles contributed mainly to the plasma clearance. Only liver and the kidneys, however, were responsible for the uptake and subsequent degradation of BM 06.022 and contributed for 75% to the catabolism of BM 06.022. BM 06.022 was degraded in the lysosomal compartment of both organs. Parenchymal liver cells were responsible for 70% of the liver uptake of BM 06.022. BM 06.022 associated rapidly to isolated rat parenchymal liver cells and was subsequently degraded in the lysosomal compartment of these cells. BM 06.022 bound with low-affinity to the parenchymal liver cells (550 nM) and the binding of BM 06.022 could be displaced by t-PA (IC50 5.6 nM), indicating that the low-density lipoprotein receptor-related protein (LRP) could be involved in the binding of BM 06.022. GST-RAP, which is an inhibitor of LRP, could in vivo significantly inhibit the uptake of BM 06.022 in the liver.It is concluded that BM 06.022 is metabolized primarily in the liver and the kidneys. These organs take up and degrade BM 06.022 in the lysosomes. The uptake mechanism of BM 06.022 in the kidneys is unknown, while LRP is responsible for a low-affinity binding and uptake of BM 06.022 in parenchymal liver cells.

scholarly journals Circadian clock protein Rev-erbα regulates neuroinflammation

2019 ◽  
Vol 116 (11) ◽  
pp. 5102-5107 ◽  
Author(s):  
Percy Griffin ◽  
Julie M. Dimitry ◽  
Patrick W. Sheehan ◽  
Brian V. Lananna ◽  
Chun Guo ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Microglial Activation ◽  
Time Of Day ◽  
Resting State Functional Connectivity ◽  
Promoter Regions ◽  
Clock Component ◽  
Glial Cultures ◽  
Inflammatory Phenotype

Circadian dysfunction is a common attribute of many neurodegenerative diseases, most of which are associated with neuroinflammation. Circadian rhythm dysfunction has been associated with inflammation in the periphery, but the role of the core clock in neuroinflammation remains poorly understood. Here we demonstrate that Rev-erbα, a nuclear receptor and circadian clock component, is a mediator of microglial activation and neuroinflammation. We observed time-of-day oscillation in microglial immunoreactivity in the hippocampus, which was disrupted in Rev-erbα−/− mice. Rev-erbα deletion caused spontaneous microglial activation in the hippocampus and increased expression of proinflammatory transcripts, as well as secondary astrogliosis. Transcriptomic analysis of hippocampus from Rev-erbα−/− mice revealed a predominant inflammatory phenotype and suggested dysregulated NF-κB signaling. Primary Rev-erbα−/− microglia exhibited proinflammatory phenotypes and increased basal NF-κB activation. Chromatin immunoprecipitation revealed that Rev-erbα physically interacts with the promoter regions of several NF-κB–related genes in primary microglia. Loss of Rev-erbα in primary astrocytes had no effect on basal activation but did potentiate the inflammatory response to lipopolysaccharide (LPS). In vivo, Rev-erbα−/− mice exhibited enhanced hippocampal neuroinflammatory responses to peripheral LPS injection, while pharmacologic activation of Rev-erbs with the small molecule agonist SR9009 suppressed LPS-induced hippocampal neuroinflammation. Rev-erbα deletion influenced neuronal health, as conditioned media from Rev-erbα–deficient primary glial cultures exacerbated oxidative damage in cultured neurons. Rev-erbα−/− mice also exhibited significantly altered cortical resting-state functional connectivity, similar to that observed in neurodegenerative models. Our results reveal Rev-erbα as a pharmacologically accessible link between the circadian clock and neuroinflammation.

scholarly journals Serum Chemerin Levels Vary with Time of Day and Are Modified by Obesity and Tumor Necrosis Factor-α

Endocrinology ◽  
2010 ◽  
Vol 151 (6) ◽  
pp. 2590-2602 ◽  
Author(s):  
Sebastian D. Parlee ◽  
Matthew C. Ernst ◽  
Shanmugam Muruganandan ◽  
Christopher J. Sinal ◽  
Kerry B. Goralski
Keyword(s):  
Leptin Receptor ◽  
Elevated Serum ◽  
Time Of Day ◽  
Obese Mouse ◽  
Protein Synthesis Inhibitor ◽  
Low Grade ◽  
Rhythmic Pattern ◽  
Oscillatory Pattern ◽  
Primary Mouse

Chemerin is an adipokine with important regulatory roles in adipogenesis. In humans, serum total chemerin (i.e. prochemerin plus chemerin) levels are positively associated with body mass index and metabolic syndrome. However, the mechanisms that increase serum chemerin concentration are unknown. We hypothesized that chronic low-grade inflammation that occurs in obesity promotes chemerin production by adipocytes. Consistent with this, TNFα treatment of 3T3-L1 adipocytes increased bioactive chemerin levels in the cell media as detected using a CMKLR1 cell-based bioassay. This effect was blocked by the protein synthesis inhibitor cycloheximide and protein secretion inhibitor brefeldin A, indicating that TNFα may enhance prochemerin synthesis and secretion from adipocytes. In vivo, TNFα produced a time-dependent increase in serum total chemerin and bioactive chemerin. Bioactive chemerin was produced by primary mouse adipocytes and hepatocytes. Only primary adipocyte-derived chemerin was responsive to TNFα regulation implicating adipocytes as a potential source of elevated serum chemerin after TNFα exposure in vivo. In lean mice, serum total chemerin levels oscillated with peak levels occurring during daytime and trough levels at night. Comparatively, leptin- and leptin receptor-deficient obese mice, which have elevated adipose tissue expression of TNFα, displayed elevated serum total chemerin levels with an enhanced oscillatory pattern. In summary, our novel results identified TNFα as a positive regulator of adipocyte-derived chemerin. We corroborate the finding of elevated chemerin in obese humans by identifying elevated serum levels of total chemerin in two obese mouse models with a corresponding alteration in the rhythmic pattern of serum chemerin levels.

scholarly journals Daily rhythms of both host and parasite affect antimalarial drug efficacy

2021 ◽  
Author(s):  
Alíz T Y Owolabi ◽  
Sarah E Reece ◽  
Petra Schneider
Keyword(s):  
Drug Treatment ◽  
Developmental Stage ◽  
Antimalarial Drug ◽  
Drug Sensitivity ◽  
Drug Efficacy ◽  
Time Of Day ◽  
Parasite Development ◽  
Daily Rhythms ◽  
Parasite Plasmodium

Abstract Background and objectives Circadian rhythms contribute to treatment efficacy in several non-communicable diseases. However, chronotherapy (administering drugs at a particular time-of-day) against infectious diseases has been overlooked. Yet, the daily rhythms of both hosts and disease-causing agents can impact the efficacy of drug treatment. We use the rodent malaria parasite Plasmodium chabaudi, to test if the daily rhythms of hosts, parasites, and their interactions, affect sensitivity to the key antimalarial, artemisinin. Methodology Asexual malaria parasites develop rhythmically in the host’s blood, in a manner timed to coordinate with host daily rhythms. Our experiments coupled or decoupled the timing of parasite and host rhythms, and we administered artemisinin at different times of day to coincide with when parasites were either at an early (ring) or later (trophozoite) developmental stage. We quantified the impacts of parasite developmental stage, and alignment of parasite and host rhythms, on drug sensitivity. Results We find that rings were less sensitive to artemisinin than trophozoites, and this difference was exacerbated when parasite and host rhythms were misaligned, with little direct contribution of host time-of-day on its own. Furthermore, the blood concentration of haem at the point of treatment correlated positively with artemisinin efficacy but only when parasite and host rhythms were aligned. Conclusions and implications Parasite rhythms influence drug sensitivity in vivo. The hitherto unknown modulation by alignment between parasite and host daily rhythms suggests that disrupting the timing of parasite development could be a novel chronotherapeutic approach. Lay Summary We reveal that chronotherapy (providing medicines at a particular time-of-day) could improve treatment for malaria infections. Specifically, parasites’ developmental stage at the time of treatment and the coordination of timing between parasite and host both affect how well antimalarial drug treatment works.

scholarly journals Probing the Action of Permeation Enhancers Sodium Cholate and N-dodecyl-β-D-maltoside in a Porcine Jejunal Mucosal Explant System

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 172 ◽  
Author(s):  
E. Danielsen ◽  
Gert Hansen
Keyword(s):  
Brush Border ◽  
Lucifer Yellow ◽  
Membrane Integrity ◽  
Sodium Cholate ◽  
Permeability Barrier ◽  
Permeation Enhancers ◽  
Uptake Mechanism ◽  
Cell Membrane Integrity ◽  
Apical Extrusion ◽  
Small Intestinal

The small intestinal epithelium constitutes a major permeability barrier for the oral administration of therapeutic drugs with poor bioavailability, and permeation enhancers (PEs) are required to increase the paracellular and/or transcellular uptake of such drugs. Many PEs act as surfactants by perturbing cell membrane integrity and causing permeabilization by leakage or endocytosis. The aim of the present work was to study the action of sodium cholate (NaC) and N-dodecyl-β-D-maltoside (DDM), using a small intestinal mucosal explant system. At 2 mM, both NaC and DDM caused leakage into the enterocyte cytosol of the fluorescent probe Lucifer Yellow, but they also blocked the constitutive endocytotic pathway from the brush border. In addition, an increased paracellular passage of 3-kDa Texas Red Dextran into the lamina propria was observed. By electron microscopy, both PEs disrupted the hexagonal organization of microvilli of the brush border and led to the apical extrusion of vesicle-like and amorphous cell debris to the lumen. In conclusion, NaC and DDM acted in a multimodal way to increase the permeability of the jejunal epithelium both by paracellular and transcellular mechanisms. However, endocytosis, commonly thought to be an uptake mechanism that may be stimulated by PEs, was not involved in the transcellular process.

scholarly journals Body mass index, time of day, and genetics affect perivascular spaces in the white matter

2020 ◽  
Author(s):  
Giuseppe Barisano ◽  
Farshid Sepehrband ◽  
Nasim Sheikh-Bahaei ◽  
Meng Law ◽  
Arthur W. Toga
Keyword(s):  
Body Mass Index ◽  
White Matter ◽  
Body Mass ◽  
Structural Changes ◽  
Large Population ◽  
Time Of Day ◽  
Perivascular Spaces ◽  
Healthy Human ◽  
Magnetic Resonance Imaging Mri

AbstractThe analysis of cerebral perivascular spaces (PVS) using magnetic resonance imaging (MRI) allows to explore in vivo their contributions to neurological disorders. To date the normal amount and distribution of PVS in healthy human brains are not known, thus hampering our ability to define with confidence pathogenic alterations. Furthermore, it is unclear which biological factors can influence the presence and size of PVS on MRI. We performed exploratory data analysis of PVS volume and distribution in a large population of healthy individuals (n = 897, age = 28.8 ± 3.7). Here we describe the global and regional amount of PVS in the white matter, which can be used as a reference for clinicians and researchers investigating PVS and may help the interpretation of the structural changes affecting PVS in pathological states. We found a relatively high inter-subject variability in the PVS amount in this population of healthy adults (range: 1.31-14.49 cm3). We then identified body mass index, time of day, and genetics as new elements significantly affecting PVS in vivo under physiological conditions, offering a valuable foundation to future studies aimed at understanding the physiology of perivascular flow.

Circadian rhythm and response to light of extracellular glutamate and aspartate in rat suprachiasmatic nucleus

1996 ◽  
Vol 271 (3) ◽  
pp. R579-R585 ◽  
Author(s):  
S. Honma ◽  
Y. Katsuno ◽  
K. Shinohara ◽  
H. Abe ◽  
K. Honma
Keyword(s):  
Circadian Rhythm ◽  
Suprachiasmatic Nucleus ◽  
Light Pulse ◽  
Continuous Light ◽  
In Vivo Microdialysis ◽  
Dark Phase ◽  
Dark Cycle ◽  
Complete Darkness ◽  
Endogenous Circadian Rhythm

Extracellular concentrations of glutamate and aspartate were measured in the vicinity of rat suprachiasmatic nucleus (SCN) by means of in vivo microdialysis. The concentrations of both excitatory amino acids (EAAs) were higher during the dark phase than during the light under the light-dark cycle, showing pulsatile fluctuations throughout the day. When rats were released into the complete darkness, the 24-h pattern in the aspartate continued for at least one cycle, whereas that in the glutamate disappeared. The nocturnal increases in the EAA levels were not due to the increase of locomotor activity during the nighttime, because the 24-h rhythms were also detected in animals under urethan anesthesia. The patterns of extracellular EAA levels were changed when rats were released into the continuous light. Circadian rhythm was not detected in the glutamate, whereas the 24-h pattern was maintained in the aspartate with the levels increased to various extents. A 30-min light pulse given either at zeitgber time (ZT) 1 or ZT 13 elevated the EAA levels during the latter half of the light pulse, except glutamate by a pulse at ZT 1. The extracellular EAA levels in the vicinity of the rat SCN showed the circadian rhythm with a nocturnal peak and increased in response to the continuous light and a brief light pulse. The aspartate level is considered to be regulated by the endogenous circadian rhythm, but the glutamate levels seems to be modified by the light-dark cycle.

scholarly journals Chinese hamster ovary cell lysosomes rapidly exchange contents.

1987 ◽  
Vol 105 (6) ◽  
pp. 2703-2712 ◽  
Author(s):  
A L Ferris ◽  
J C Brown ◽  
R D Park ◽  
B Storrie
Keyword(s):  
Cell Fusion ◽  
Lucifer Yellow ◽  
Recipient Cell ◽  
Chinese Hamster ◽  
Donor Cell ◽  
Fluid Phase ◽  
Ovary Cell ◽  
Priming Process

We have used cell fusion to address the question of whether macromolecules are rapidly exchanged between lysosomes. Donor cell lysosomes were labeled by the long-term internalization of the fluid-phase pinocytic markers, invertase (sucrase), Lucifer Yellow, FITC-conjugated dextran, or Texas red-conjugated dextran. Recipient cells contained lysosomes swollen by long-term internalization of dilute sucrose or marked by an overnight FITC-dextran uptake. Cells were incubated for 1 or 2 h in marker-free media before cell fusion to clear any marker from an endosomal compartment. Recipient cells were infected with vesicular stomatitis virus as a fusogen. Donor and recipient cells were co-cultured for 1 or 2 h and then fused by a brief exposure to pH 5. In all cases, extensive exchange of content between donor and recipient cell lysosomes was observed at 37 degrees C. Incubation of cell syncytia at 17 degrees C blocked lysosome/lysosome exchange, although a "priming" process(es) appeared to occur at 17 degrees C. The kinetics of lysosome/lysosome exchange in fusions between cells containing invertase-positive lysosomes and sucrose-positive lysosomes indicated that lysosome/lysosome exchange was as rapid, if not more rapid, than endosome/lysosome exchange. These experiments suggest that in vivo the lysosome is a rapidly intermixing organellar compartment.

scholarly journals Body mass index, time of day, and genetics affect perivascular spaces in the white matter

2020 ◽  
pp. 0271678X2097285
Author(s):  
Giuseppe Barisano ◽  
Nasim Sheikh-Bahaei ◽  
Meng Law ◽  
Arthur W Toga ◽  
Farshid Sepehrband
Keyword(s):  
Body Mass Index ◽  
White Matter ◽  
Body Mass ◽  
Structural Changes ◽  
Large Population ◽  
Time Of Day ◽  
Perivascular Spaces ◽  
Healthy Human ◽  
Magnetic Resonance Imaging Mri

The analysis of cerebral perivascular spaces (PVS) using magnetic resonance imaging (MRI) allows to explore in vivo their contributions to neurological disorders. To date the normal amount and distribution of PVS in healthy human brains are not known, thus hampering our ability to define with confidence pathogenic alterations. Furthermore, it is unclear which biological factors can influence the presence and size of PVS on MRI. We performed exploratory data analysis of PVS volume and distribution in a large population of healthy individuals (n = 897, age = 28.8 ± 3.7). Here we describe the global and regional amount of PVS in the white matter, which can be used as a reference for clinicians and researchers investigating PVS and may help the interpretation of the structural changes affecting PVS in pathological states. We found a relatively high inter-subject variability in the PVS amount in this population of healthy adults (range: 1.31–14.49 cm3). The PVS volume was higher in older and male individuals. Moreover, we identified body mass index, time of day, and genetics as new elements significantly affecting PVS in vivo under physiological conditions, offering a valuable foundation to future studies aimed at understanding the physiology of perivascular flow.

scholarly journals Internalization mechanisms of cell-penetrating peptides

2020 ◽  
Vol 11 ◽  
pp. 101-123 ◽  
Author(s):  
Ivana Ruseska ◽  
Andreas Zimmer
Keyword(s):  
Cellular Uptake ◽  
Cell Types ◽  
Cell Penetrating Peptides ◽  
Uptake Mechanism ◽  
Black And White ◽  
Cell Penetrating ◽  
Basic Peptides ◽  
Different Cell Types ◽  
Immense Potential

In today’s modern era of medicine, macromolecular compounds such as proteins, peptides and nucleic acids are dethroning small molecules as leading therapeutics. Given their immense potential, they are highly sought after. However, their application is limited mostly due to their poor in vivo stability, limited cellular uptake and insufficient target specificity. Cell-penetrating peptides (CPPs) represent a major breakthrough for the transport of macromolecules. They have been shown to successfully deliver proteins, peptides, siRNAs and pDNA in different cell types. In general, CPPs are basic peptides with a positive charge at physiological pH. They are able to translocate membranes and gain entry to the cell interior. Nevertheless, the mechanism they use to enter cells still remains an unsolved piece of the puzzle. Endocytosis and direct penetration have been suggested as the two major mechanisms used for internalization, however, it is not all black and white in the nanoworld. Studies have shown that several CPPs are able to induce and shift between different uptake mechanisms depending on their concentration, cargo or the cell line used. This review will focus on the major internalization pathways CPPs exploit, their characteristics and regulation, as well as some of the factors that influence the cellular uptake mechanism.

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