Central regulation of photosensitive membrane turnover in the lateral eye of Limulus. I. Octopamine primes the retina for daily transient rhabdom shedding

2002 ◽  
Vol 19 (3) ◽  
pp. 283-297 ◽  
Author(s):  
RASHMI V. KHADILKAR ◽  
JOHN R. MYTINGER ◽  
LAURA E. THOMASON ◽  
SCOTT L. RUNYON ◽  
KEVIN J. WASHICOSKY ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Circadian Rhythms ◽  
Internal Control ◽  
Circadian Clocks ◽  
Central Regulation ◽  
Membrane Turnover ◽  
Complex Interactions ◽  
Lateral Eye ◽  
Central Clock

Limulus lateral eyes shed and renew a portion of their photosensitive membrane (rhabdom) daily. Shedding, in many species including Limulus, is regulated by complex interactions between circadian rhythms and light. Little is known about how circadian clocks and photoreceptors communicate to regulate shedding. Limulus photoreceptors do not contain an endogenous circadian oscillator, but rely upon efferent outflow from a central clock for circadian timing. To investigate whether the putative efferent neurotransmitter octopamine (OA) communicates circadian rhythms that prime the lateral eye for transient rhabdom shedding, we decoupled photoreceptors from the clock by transecting the lateral optic nerve (contains the retinal efferent fibers). Overnight (6 h) intraretinal injections of 40 μM OA restored transient shedding to lateral eyes with transected nerves to levels comparable to those of intact internal control eyes. To determine whether OA acts alone in communicating circadian rhythms that prime the lateral eye for transient shedding, we “primed” eyes with intact nerves for transient shedding with exogenous OA during subjective day. In nature, lateral eyes shed their rhabdoms only once a day at dawn following overnight efferent priming. Eyes in animals placed in darkness during subjective day, when the retinal efferents are quiescent, and injected for 6 h with 40 μM OA shed their rhabdoms in response to a second introduction to light. Untreated control eyes of the same animals did not. The same results were observed in vitro in lateral eyes treated similarly. Octopamine is the only efferent neurotransmitter/messenger required to make lateral eyes competent for transient shedding. Phentolamine, an OA receptor antagonist, reduced the number of photoreceptors primed for transient shedding and the amount of rhabdom shed in those photoreceptors suggesting that OA acts via a specific OA receptor.

scholarly journals The Kidney Clock Contributes to Timekeeping by the Master Circadian Clock

2019 ◽  
Vol 20 (11) ◽  
pp. 2765 ◽  
Author(s):  
Jihwan Myung ◽  
Mei-Yi Wu ◽  
Chun-Ya Lee ◽  
Amalia Ridla Rahim ◽  
Vuong Hung Truong ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Sleep Disturbances ◽  
The Body ◽  
Circadian Clocks ◽  
Whole Body ◽  
The Hierarchical Structure ◽  
Body Level ◽  
The Brain ◽  
Master Clock

The kidney harbors one of the strongest circadian clocks in the body. Kidney failure has long been known to cause circadian sleep disturbances. Using an adenine-induced model of chronic kidney disease (CKD) in mice, we probe the possibility that such sleep disturbances originate from aberrant circadian rhythms in kidney. Under the CKD condition, mice developed unstable behavioral circadian rhythms. When observed in isolation in vitro, the pacing of the master clock, the suprachiasmatic nucleus (SCN), remained uncompromised, while the kidney clock became a less robust circadian oscillator with a longer period. We find this analogous to the silencing of a strong slave clock in the brain, the choroid plexus, which alters the pacing of the SCN. We propose that the kidney also contributes to overall circadian timekeeping at the whole-body level, through bottom-up feedback in the hierarchical structure of the mammalian circadian clocks.

The Use of the Chorioallantoic Membrane (CAM) of the Embryonic Chick for the Direct Assessment of Implant Toxicity

1985 ◽  
Vol 13 (4) ◽  
pp. 261-266
Author(s):  
P.P. Monro ◽  
D.P. Knight ◽  
W.S. Pringle ◽  
D.M. Fyfe ◽  
J.R. Shearer
Keyword(s):  
Chorioallantoic Membrane ◽  
In Vitro Techniques ◽  
Implant Materials ◽  
Metal Foils ◽  
Complex Interactions ◽  
Cobalt Nickel ◽  
Histological Criteria ◽  
Fluid Environment

The toxicity of implant materials requires investigation prior to clinical use. We have developed a method where materials are directly applied to the chorioallantoic membrane (CAM) of 9-day-old chick embryos and toxicity is assessed using histological criteria. We evaluated the method using metal foils. The number and organisation of fibroblasts seemed to be the most useful criteria for assessing metal toxicity. Differences were greatest after 10 days of culture on the CAM. The method is sensitive enough to enable us to discriminate between the less toxic aluminium and titanium and the highly toxic cobalt, nickel and tungsten. The proposed method has advantages over in vitro techniques which provide an abnormal fluid environment and in which the more complex interactions that are possible between implant materials and tissue in vivo cannot be modelled.

scholarly journals Adipose and Muscle Cell Co-Culture System: A Novel In Vitro Tool to Mimic the In Vivo Cellular Environment

Biology ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Palaniselvam Kuppusamy ◽  
Dahye Kim ◽  
Ilavenil Soundharrajan ◽  
Inho Hwang ◽  
Ki Choon Choi
Keyword(s):  
Drug Development ◽  
Culture System ◽  
Cell Types ◽  
Culture Cell ◽  
In Vitro Techniques ◽  
Culture Systems ◽  
Complex Interactions ◽  
Cellular Environment

A co-culture system allows researchers to investigate the complex interactions between two cell types under various environments, such as those that promote differentiation and growth as well as those that mimic healthy and diseased states, in vitro. In this paper, we review the most common co-culture systems for myocytes and adipocytes. The in vitro techniques mimic the in vivo environment and are used to investigate the causal relationships between different cell lines. Here, we briefly discuss mono-culture and co-culture cell systems and their applicability to the study of communication between two or more cell types, including adipocytes and myocytes. Also, we provide details about the different types of co-culture systems and their applicability to the study of metabolic disease, drug development, and the role of secretory factors in cell signaling cascades. Therefore, this review provides details about the co-culture systems used to study the complex interactions between adipose and muscle cells in various environments, such as those that promote cell differentiation and growth and those used for drug development.

scholarly journals Glioblastoma infiltration into central nervous system tissue in vitro: involvement of a metalloprotease.

1988 ◽  
Vol 107 (6) ◽  
pp. 2281-2291 ◽  
Author(s):  
P A Paganetti ◽  
P Caroni ◽  
M E Schwab
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
White Matter ◽  
Optic Nerve ◽  
Cell Attachment ◽  
Neurite Growth ◽  
Cell Spreading ◽  
C6 Cells ◽  
3T3 Fibroblasts

Differentiated oligodendrocytes and central nervous system (CNS) myelin are nonpermissive substrates for neurite growth and for cell attachment and spreading. This property is due to the presence of membrane-bound inhibitory proteins of 35 and 250 kD and is specifically neutralized by monoclonal antibody IN-1 (Caroni, P., and M. E. Schwab. 1988. Neuron. 1:85-96). Using rat optic nerve explants, CNS frozen sections, cultured oligodendrocytes or CNS myelin, we show here that highly invasive CNS tumor line (C6 glioblastoma) was not inhibited by these myelin-associated inhibitory components. Lack of inhibition was due to a specific mechanism as the metalloenzyme blocker 1,10-phenanthroline and two synthetic dipeptides containing metalloprotease-blocking sequences (gly-phe, tyr-tyr) specifically impaired C6 cell spreading on CNS myelin. In the presence of these inhibitors, C6 cells were affected by the IN-1-sensitive inhibitors in the same manner as control cells, e.g., 3T3 fibroblasts or B16 melanomas. Specific blockers of the serine, cysteine, and aspartyl protease classes had no effect. C6 cell spreading on inhibitor-free substrates such as CNS gray matter, peripheral nervous system myelin, glass, or poly-D-lysine was not sensitive to 1,10-phenanthroline. The nonpermissive substrate properties of CNS myelin were strongly reduced by incubation with a plasma membrane fraction prepared from C6 cells. This reduction was sensitive to the same inhibitors of metalloproteases. In our in vitro model for CNS white matter invasion, cell infiltration of optic nerve explants, which occurred with C6 cells but not with 3T3 fibroblasts or B16 melanomas, was impaired by the presence of the metalloprotease blockers. These results suggest that C6 cell infiltrative behavior in CNS white matter in vitro occurs by means of a metalloproteolytic activity, which probably acts on the myelin-associated inhibitory substrates.

scholarly journals Cross-talk among flesh-eating Aeromonas hydrophila strains in mixed infection leading to necrotizing fasciitis

2016 ◽  
Vol 113 (3) ◽  
pp. 722-727 ◽  
Author(s):  
Duraisamy Ponnusamy ◽  
Elena V. Kozlova ◽  
Jian Sha ◽  
Tatiana E. Erova ◽  
Sasha R. Azar ◽  
...  
Keyword(s):  
Necrotizing Fasciitis ◽  
Mixed Infection ◽  
Aeromonas Hydrophila ◽  
Case Fatality ◽  
Host Immune System ◽  
Complex Interactions ◽  
Solid Media ◽  
Multiple Strains ◽  
Highly Virulent

Necrotizing fasciitis (NF) caused by flesh-eating bacteria is associated with high case fatality. In an earlier study, we reported infection of an immunocompetent individual with multiple strains of Aeromonas hydrophila (NF1–NF4), the latter three constituted a clonal group whereas NF1 was phylogenetically distinct. To understand the complex interactions of these strains in NF pathophysiology, a mouse model was used, whereby either single or mixed A. hydrophila strains were injected intramuscularly. NF2, which harbors exotoxin A (exoA) gene, was highly virulent when injected alone, but its virulence was attenuated in the presence of NF1 (exoA-minus). NF1 alone, although not lethal to animals, became highly virulent when combined with NF2, its virulence augmented by cis-exoA expression when injected alone in mice. Based on metagenomics and microbiological analyses, it was found that, in mixed infection, NF1 selectively disseminated to mouse peripheral organs, whereas the other strains (NF2, NF3, and NF4) were confined to the injection site and eventually cleared. In vitro studies showed NF2 to be more effectively phagocytized and killed by macrophages than NF1. NF1 inhibited growth of NF2 on solid media, but ExoA of NF2 augmented virulence of NF1 and the presence of NF1 facilitated clearance of NF2 from animals either by enhanced priming of host immune system or direct killing via a contact-dependent mechanism.

Current trends in mathematical modeling of tumor–microenvironment interactions: a survey of tools and applications

2010 ◽  
Vol 235 (4) ◽  
pp. 411-423 ◽  
Author(s):  
Katarzyna A Rejniak ◽  
Lisa J McCawley
Keyword(s):  
Mathematical Modeling ◽  
Protein Interactions ◽  
Computational Models ◽  
Chemical Species ◽  
Tumor Stroma ◽  
Cellular Functions ◽  
Complex Interactions ◽  
Expanding Population

In its simplest description, a tumor is comprised of an expanding population of transformed cells supported by a surrounding microenvironment termed the tumor stroma. The tumor microcroenvironment has a very complex composition, including multiple types of stromal cells, a dense network of various extracellular matrix (ECM) fibers interpenetrated by the interstitial fluid and gradients of several chemical species that either are dissolved in the fluid or are bound to the ECM structure. In order to study experimentally such complex interactions between multiple players, cancer is dissected and considered at different scales of complexity, such as protein interactions, biochemical pathways, cellular functions or whole organism studies. However, the integration of information acquired from these studies into a common description is as difficult as the disease itself. Computational models of cancer can provide cancer researchers with invaluable tools that are capable of integrating the complexity into organizing principles as well as suggesting testable hypotheses. We will focus in this Minireview on mathematical models in which the whole cell is a main modeling unit. We will present a current stage of such cell-focused mathematical modeling incorporating different stromal components and their interactions with growing tumors, and discuss what modeling approaches can be undertaken to complement the in vivo and in vitro experimentation.

Clock gene-independent daily regulation of haemoglobin oxidation in red blood cells

2021 ◽  
Author(s):  
Andrew D. Beale ◽  
Priya Crosby ◽  
Utham K. Valekunja ◽  
Rachel S. Edgar ◽  
Johanna E. Chesham ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Human Subjects ◽  
Developmental Regulation ◽  
Physiological Role ◽  
Cell Types ◽  
The Body

AbstractCellular circadian rhythms confer daily temporal organisation upon behaviour and physiology that is fundamental to human health and disease. Rhythms are present in red blood cells (RBCs), the most abundant cell type in the body. Being naturally anucleate, RBC circadian rhythms share key elements of post-translational, but not transcriptional, regulation with other cell types. The physiological function and developmental regulation of RBC circadian rhythms is poorly understood, however, partly due to the small number of appropriate techniques available. Here, we extend the RBC circadian toolkit with a novel biochemical assay for haemoglobin oxidation status, termed “Bloody Blotting”. Our approach relies on a redox-sensitive covalent haem-haemoglobin linkage that forms during cell lysis. Formation of this linkage exhibits daily rhythms in vitro, which are unaffected by mutations that affect the timing of circadian rhythms in nucleated cells. In vivo, haemoglobin oxidation rhythms demonstrate daily variation in the oxygen-carrying and nitrite reductase capacity of the blood, and are seen in human subjects under controlled laboratory conditions as well as in freely-behaving humans. These results extend our molecular understanding of RBC circadian rhythms and suggest they serve an important physiological role in gas transport.

In vitro evaluation of reactive astrocyte migration, a component of tissue remodeling in glaucomatous optic nerve head

Glia ◽  
2001 ◽  
Vol 34 (3) ◽  
pp. 178-189 ◽  
Author(s):  
G�lg�n Tezel ◽  
M. Rosario Hernandez ◽  
Martin B. Wax
Keyword(s):  
Optic Nerve ◽  
Optic Nerve Head ◽  
Tissue Remodeling ◽  
Reactive Astrocyte ◽  
In Vitro Evaluation

scholarly journals Interaction between photoperiod and variation in circadian rhythms in tomato

2022 ◽  
Author(s):  
Yanli Xiang ◽  
Thomas Sapir ◽  
Pauline Rouillard ◽  
Marina Ferrand ◽  
Jose M Jimenez-Gomez
Keyword(s):  
Seasonal Variation ◽  
Circadian Rhythms ◽  
Phase Shift ◽  
Circadian Clock ◽  
Environmental Changes ◽  
Circadian Clocks ◽  
Biological Processes ◽  
Near Isogenic Lines ◽  
Transcriptomic Profiling ◽  
Isogenic Lines

Many biological processes follow circadian rhythmicity and are controlled by the circadian clock. Predictable environmental changes such as seasonal variation in photoperiod can modulate circadian rhythms, allowing organisms to adjust to the time of the year. Modification of circadian clocks is especially relevant in crops to enhance their cultivability in specific regions by changing their sensibility to photoperiod. In tomato, the appearance of mutations in EMPFINDLICHER IM DUNKELROTEN LICHT 1 (EID1, Solyc09g075080) and NIGHT LIGHT-INDUCIBLE AND CLOCK-REGULATED GENE 2 (LNK2, Solyc01g068560) during domestication delayed its circadian rhythms, and allowed its expansion outside its equatorial origin. Here we study how variation in circadian rhythms in tomato affects its perception of photoperiod. To do this, we create near isogenic lines carrying combinations of wild alleles of EID1 and LNK2 and perform transcriptomic profiling under two different photoperiods. We observe that EID1, but not LNK2, has a large effect on the tomato transcriptome and its response to photoperiod. This large effect of EID1 is likely a consequence of the global phase shift elicited by this gene in tomato's circadian rhythms.

Sign in / Sign up

Export Citation Format

Share Document