A study of the molecular–cellular interface in visual photoreceptors by light scattering photometry

1985 ◽  
Vol 63 (7) ◽  
pp. 1933-1939 ◽  
Author(s):  
T. Borys ◽  
S. Deshpande ◽  
R. Jones ◽  
E. W. Abrahamson
Keyword(s):  
Light Scattering ◽  
Structural Changes ◽  
Time Range ◽  
Relaxation Techniques ◽  
Cell Organelles ◽  
Whole Cells ◽  
Cellular Events ◽  
Molecular Events ◽  
Cytological Changes ◽  
Non Destructive

The correlation of molecular events with structural changes within the cell requires a non-destructive relaxation technique that can be adapted to measure such cellular changes in a time range of milliseconds to minutes. Light scattering relaxation techniques have proved useful for such studies as they can often be measured simultaneously or in parallel with absorption or fluorescence spectral changes characterizing molecular or macromolecular processes. Such techniques are proving useful in the study of photobiological processes such as visual photoreception where specific cytological changes produced photochemically can be effected by alternate controlled perturbations such as osmotic shrinking or swelling of cell organelles and (or) whole cells. This paper illustrates how light scattering relaxation spectrophotometry can be applied to the correlation of molecular and cellular events in visual photoreceptors.

scholarly journals Cellular and System Biology of Memory: Timing, Molecules, and Beyond

2016 ◽  
Vol 96 (2) ◽  
pp. 647-693 ◽  
Author(s):  
Martin Korte ◽  
Dietmar Schmitz
Keyword(s):  
Structural Changes ◽  
Cell Types ◽  
Information Storage ◽  
Memory Storage ◽  
System Level ◽  
Time Range ◽  
Long Term Memory ◽  
Molecular Events ◽  
Multistep Process ◽  
Long Time

The storage of information in the mammalian nervous systems is dependent on a delicate balance between change and stability of neuronal networks. The induction and maintenance of processes that lead to changes in synaptic strength to a multistep process which can lead to long-lasting changes, which starts and ends with a highly choreographed and perfectly timed dance of molecules in different cell types of the central nervous system. This is accompanied by synchronization of specific networks, resulting in the generation of characteristic “macroscopic” rhythmic electrical fields, whose characteristic frequencies correspond to certain activity and information-processing states of the brain. Molecular events and macroscopic fields influence each other reciprocally. We review here cellular processes of synaptic plasticity, particularly functional and structural changes, and focus on timing events that are important for the initial memory acquisition, as well as mechanisms of short- and long-term memory storage. Then, we cover the importance of epigenetic events on the long-time range. Furthermore, we consider how brain rhythms at the network level participate in processes of information storage and by what means they participating in it. Finally, we examine memory consolidation at the system level during processes of sleep.

scholarly journals Epigenetic Effects Induced by Methamphetamine and Methamphetamine-Dependent Oxidative Stress

2018 ◽  
Vol 2018 ◽  
pp. 1-28 ◽  
Author(s):  
Fiona Limanaqi ◽  
Stefano Gambardella ◽  
Francesca Biagioni ◽  
Carla L. Busceti ◽  
Francesco Fornai
Keyword(s):  
Molecular Mechanisms ◽  
Neuropsychiatric Disorders ◽  
Behavioral Alterations ◽  
Neuronal Phenotype ◽  
Cellular Events ◽  
Epigenetic Effects ◽  
Molecular Events ◽  
Epigenetic Events ◽  
Genetic Modifications ◽  
Altered Gene

Methamphetamine is a widely abused drug, which possesses neurotoxic activity and powerful addictive effects. Understanding methamphetamine toxicity is key beyond the field of drug abuse since it allows getting an insight into the molecular mechanisms which operate in a variety of neuropsychiatric disorders. In fact, key alterations produced by methamphetamine involve dopamine neurotransmission in a way, which is reminiscent of spontaneous neurodegeneration and psychiatric schizophrenia. Thus, understanding the molecular mechanisms operated by methamphetamine represents a wide window to understand both the addicted brain and a variety of neuropsychiatric disorders. This overlapping, which is already present when looking at the molecular and cellular events promoted immediately after methamphetamine intake, becomes impressive when plastic changes induced in the brain of methamphetamine-addicted patients are considered. Thus, the present manuscript is an attempt to encompass all the molecular events starting at the presynaptic dopamine terminals to reach the nucleus of postsynaptic neurons to explain how specific neurotransmitters and signaling cascades produce persistent genetic modifications, which shift neuronal phenotype and induce behavioral alterations. A special emphasis is posed on disclosing those early and delayed molecular events, which translate an altered neurotransmitter function into epigenetic events, which are derived from the translation of postsynaptic noncanonical signaling into altered gene regulation. All epigenetic effects are considered in light of their persistent changes induced in the postsynaptic neurons including sensitization and desensitization, priming, and shift of neuronal phenotype.

scholarly journals Drosophila Neuronal Injury Follows a Temporal Sequence of Cellular Events Leading to Degeneration at the Neuromuscular Junction

2015 ◽  
Vol 9s2 ◽  
pp. JEN.S25516 ◽  
Author(s):  
Barron L. Lincoln ◽  
Sahar H. Alabsi ◽  
Nicholas Frendo ◽  
Robert Freund ◽  
Lani C. Keller
Keyword(s):  
Neuromuscular Junction ◽  
Model Organism ◽  
Structural Defects ◽  
Cellular Mechanisms ◽  
Post Injury ◽  
Ubiquitinated Proteins ◽  
Cellular Events ◽  
Molecular Events ◽  
Complex Signaling

Neurodegenerative diseases affect millions of people worldwide, and as the global population ages, there is a critical need to improve our understanding of the molecular and cellular mechanisms that drive neurodegeneration. At the molecular level, neurodegeneration involves the activation of complex signaling pathways that drive the active destruction of neurons and their intracellular components. Here, we use an in vivo motor neuron injury assay to acutely induce neurodegeneration in order to follow the temporal order of events that occur following injury in Drosophila melanogaster. We find that sites of injury can be rapidly identified based on structural defects to the neuronal cytoskeleton that result in disrupted axonal transport. Additionally, the neuromuscular junction accumulates ubiquitinated proteins prior to the neurodegenerative events, occurring at 24 hours post injury. Our data provide insights into the early molecular events that occur during axonal and neuromuscular degeneration in a genetically tractable model organism. Importantly, the mechanisms that mediate neurodegeneration in flies are conserved in humans. Thus, these studies have implications for our understanding of the cellular and molecular events that occur in humans and will facilitate the identification of biomedically relevant targets for future treatments.

scholarly journals The unfolding and refolding of glutamate dehydrogenases from bovine liver, baker's yeast and Clostridium symbosium

1988 ◽  
Vol 251 (1) ◽  
pp. 135-139 ◽  
Author(s):  
S M West ◽  
N C Price
Keyword(s):  
Enzyme Activity ◽  
Light Scattering ◽  
Liver Enzyme ◽  
Structural Changes ◽  
Bovine Liver ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Guanidinium Chloride ◽  
Reversible Loss ◽  
Parallel Behaviour

The unfolding behaviour of the hexameric glutamate dehydrogenases from bovine liver, Clostridium symbosium and baker's yeast in solutions of guanidinium chloride (GdnHCl) was studied. Changes in Mr studied by light-scattering indicate that, in each case, the hexamer dissociates to form trimers, which then dissociate to monomers at higher concentrations of GdnHCl. Dissociation to trimers is accompanied by a reversible loss of enzyme activity, but no gross structural changes can be detected by fluorescence or c.d. Dissociation to monomers is accompanied by large structural changes, and the loss of activity cannot be reversed by dilution. The parallel behaviour of all three enzymes shows that the previously noted inability of the isolated subunits of the bovine liver enzyme to refold [Bell & Bell (1984) Biochem. J. 217, 327-330] is not a result of any modification of the enzyme as a result of import into mitochondria, since the C. symbosium and baker's-yeast enzymes do not undergo any such post-translational translocation.

Non Destructive Characterization of Concrete Joints Using the Scaling Subtraction Method

2009 ◽  
Vol 417-418 ◽  
pp. 41-44
Author(s):  
Paola Antonaci ◽  
Pietro G. Bocca ◽  
Caterina L.E. Bruno ◽  
Antonio S. Gliozzi ◽  
Marco Scalerandi
Keyword(s):  
Structural Changes ◽  
Crack Opening ◽  
Subtraction Method ◽  
Damage Initiation ◽  
External Pressures ◽  
Concrete Joints ◽  
Non Destructive ◽  
Non Destructive Characterization ◽  
Potential Conditions

The evolution of concrete behavior in the proximity of a joint under the effect of varying external pressures is studied by means of a novel nonlinear ultrasonic technique denoted as Scaling Subtraction Method. The results obtained show that the proposed method is effective in describing the occurrence of micro-structural changes near the joint and detect potential conditions for crack opening and damage initiation.

Non-Destructive Tracking of Structural Changes of Concrete Mixtures during Thermal Stress

2014 ◽  
Vol 617 ◽  
pp. 152-155 ◽  
Author(s):  
Ivo Kusák ◽  
Miroslav Lunak ◽  
Zdeněk Chobola
Keyword(s):  
Thermal Stress ◽  
Structural Reliability ◽  
Structural Changes ◽  
Dielectric Material ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Model Parameters ◽  
Debye Theory ◽  
Concrete Mixtures ◽  
Non Destructive

This paper deals with the application of the method of impedance spectroscopy to testing of cement-based composites prepared from a mix of cement mortar and quartz sand, which were intentionally degraded by high-temperature treatment (in the temperatures range from 25 °C to 400 °C). The monitoring of structural changes in the thermal stress is very important, for example for determining the reliability of the whole structure. Based on the Debye theory of dielectric the models were created, their applications and received parameters measured dielectric material is characterized and discussed the uniqueness of determining the values of model parameters. Development of electrical parameters and permittivity at each temperature areas reliably show these structural changes and thus the structural reliability.

scholarly journals Poorly Understood Aspects of Striated Muscle Contraction

2015 ◽  
Vol 2015 ◽  
pp. 1-28 ◽  
Author(s):  
Alf Månsson ◽  
Dilson Rassier ◽  
Georgios Tsiavaliaris
Keyword(s):  
Muscle Contraction ◽  
Structural Changes ◽  
Striated Muscle ◽  
Three Dimensional ◽  
Skeletal Muscle Function ◽  
Tension Development ◽  
Atomic Structures ◽  
Molecular Events ◽  
Physiological Properties

Muscle contraction results from cyclic interactions between the contractile proteins myosin and actin, driven by the turnover of adenosine triphosphate (ATP). Despite intense studies, several molecular events in the contraction process are poorly understood, including the relationship between force-generation and phosphate-release in the ATP-turnover. Different aspects of the force-generating transition are reflected in the changes in tension development by muscle cells, myofibrils and single molecules upon changes in temperature, altered phosphate concentration, or length perturbations. It has been notoriously difficult to explain all these events within a given theoretical framework and to unequivocally correlate observed events with the atomic structures of the myosin motor. Other incompletely understood issues include the role of the two heads of myosin II and structural changes in the actin filaments as well as the importance of the three-dimensional order. We here review these issues in relation to controversies regarding basic physiological properties of striated muscle. We also briefly consider actomyosin mutation effects in cardiac and skeletal muscle function and the possibility to treat these defects by drugs.

Structural changes in microemulsions by light scattering

1978 ◽  
Vol 25 (2) ◽  
pp. 144-148 ◽  
Author(s):  
S. Ballarò ◽  
F. Mallamace ◽  
F. Wanderlingh
Keyword(s):  
Light Scattering ◽  
Structural Changes

scholarly journals Photoactivation mechanism of a carotenoid-based photoreceptor

2017 ◽  
Vol 114 (24) ◽  
pp. 6286-6291 ◽  
Author(s):  
Sepalika Bandara ◽  
Zhong Ren ◽  
Lu Lu ◽  
Xiaoli Zeng ◽  
Heewhan Shin ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Direct Interaction ◽  
Water Soluble ◽  
Site Directed Mutagenesis ◽  
Photochemical Property ◽  
Direct Observations ◽  
Absorbing State ◽  
Molecular Events ◽  
Orange Carotenoid Protein

Photoprotection is essential for efficient photosynthesis. Cyanobacteria have evolved a unique photoprotective mechanism mediated by a water-soluble carotenoid-based photoreceptor known as orange carotenoid protein (OCP). OCP undergoes large conformational changes in response to intense blue light, and the photoactivated OCP facilitates dissipation of excess energy via direct interaction with allophycocyanins at the phycobilisome core. However, the structural events leading up to the OCP photoactivation remain elusive at the molecular level. Here we present direct observations of light-induced structural changes in OCP captured by dynamic crystallography. Difference electron densities between the dark and illuminated states reveal widespread and concerted atomic motions that lead to altered protein–pigment interactions, displacement of secondary structures, and domain separation. Based on these crystallographic observations together with site-directed mutagenesis, we propose a molecular mechanism for OCP light perception, in which the photochemical property of a conjugated carbonyl group is exploited. We hypothesize that the OCP photoactivation starts with keto–enol tautomerization of the essential 4-keto group in the carotenoid, which disrupts the strong hydrogen bonds between the bent chromophore and the protein moiety. Subsequent structural changes trapped in the crystal lattice offer a high-resolution glimpse of the initial molecular events as OCP begins to transition from the orange-absorbing state to the active red-absorbing state.

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