Optogenetic study of central medial and paraventricular thalamic projections to the basolateral amygdala

2021 ◽  
Author(s):  
Nowrin Ahmed ◽  
Drew B Headley ◽  
Denis Pare
Keyword(s):  
Basolateral Amygdala ◽  
Feedback Inhibition ◽  
Thalamic Nuclei ◽  
Electron Microscopic ◽  
Local Circuit ◽  
Principal Cells ◽  
Axon Terminals ◽  
Microscopic Studies ◽  
The Impact

The central medial (CMT) and paraventricular (PVT) thalamic nuclei project strongly to the basolateral amygdala (BL). Similarities between the responsiveness of CMT, PVT, and BL neurons suggest that these nuclei strongly influence BL activity. Supporting this possibility, an electron microscopic study reported that in contrast with other extrinsic afferents, CMT and PVT axon terminals form very few synapses with BL interneurons. However, since limited sampling is a concern in electron microscopic studies, the present investigation was undertaken to compare the impact of CMT and PVT thalamic inputs on principal and local-circuit BL neurons using optogenetic methods and whole-cell recordings in vitro. Optogenetic stimulation of CMT and PVT axons elicited glutamatergic EPSPs or EPSCs in principal cells and interneurons, but they generally had a longer latency in interneurons. Moreover, after blockade of polysynaptic interactions with tetrodotoxin (TTX), a lower proportion of interneurons (50%) than principal cells (90%) remained responsive to CMT and PVT inputs. While the presence of TTX-resistant responses in some interneurons indicates that CMT and PVT inputs directly contact some local-circuit cells, their lower incidence and amplitude after TTX suggest that CMT and PVT inputs form fewer synapses with them than with principal BL cells. Together, these results indicate that CMT and PVT inputs mainly contact principal BL neurons such that when CMT or PVT neurons fire, limited feed-forward inhibition counters their excitatory influence over principal BL cells. However, CMT and PVT axons can also recruit interneurons indirectly, via the activation of principal cells, thereby generating feedback inhibition.

Cytoplasmic Granules in Lymphocytes from Rats Dosed with SK&F 14336-D

1971 ◽  
Vol 29 ◽  
pp. 556-557
Author(s):  
T. G. Merrill ◽  
B. J. Payne ◽  
A. J. Tousimis
Keyword(s):  
Lipid Storage ◽  
Pokeweed Mitogen ◽  
Electron Microscopic ◽  
Cytoplasmic Granules ◽  
Storage Diseases ◽  
Tay Sachs Disease ◽  
Large Numbers ◽  
Microscopic Studies ◽  
Neurovisceral Lipidosis

Rats given SK&F 14336-D (9-[3-Dimethylamino propyl]-2-chloroacridane), a tranquilizing drug, developed an increased number of vacuolated lymphocytes as observed by light microscopy. Vacuoles in peripheral blood of rats and humans apparently are rare and are not usually reported in differential counts. Transforming agents such as phytohemagglutinin and pokeweed mitogen induce similar vacuoles in in vitro cultures of lymphocytes. These vacuoles have also been reported in some of the lipid-storage diseases of humans such as amaurotic familial idiocy, familial neurovisceral lipidosis, lipomucopolysaccharidosis and sphingomyelinosis. Electron microscopic studies of Tay-Sachs' disease and of chloroquine treated swine have demonstrated large numbers of “membranous cytoplasmic granules” in the cytoplasm of neurons, in addition to lymphocytes. The present study was undertaken with the purpose of characterizing the membranous inclusions and developing an experimental animal model which may be used for the study of lipid storage diseases.

Estramustine binds MAP-2 to inhibit microtubule assembly in vitro

1988 ◽  
Vol 89 (3) ◽  
pp. 331-342
Author(s):  
M.E. Stearns ◽  
K.D. Tew
Keyword(s):  
Linear Regression Analysis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Microtubule Assembly ◽  
Scatchard Analysis ◽  
Binding Assays ◽  
Electron Microscopic ◽  
Associated Proteins ◽  
Microscopic Studies

We have investigated the ability of estramustine to bind to rat brain microtubule-associated proteins (MAPs) and purified MAP-2 in vitro. [3H]estramustine's relative affinity for tubulin and MAPs was assessed by gel filtration chromatography, immunoprecipitation and binding assays. Scatchard analysis demonstrated a specific affinity of the drug for MAP-2. Calculations from kinetic parameters and non-linear regression analysis gave a Kd of 15 microM, and a Bmax of 3.4 × 10(−7)M ml-1. Extrapolation of this value suggested that each MAP-2 molecule binds approximately 20 molecules of estramustine. Microtubule assembly studies and SDS-polyacrylamide gel electrophoresis revealed that at 20–60 microM levels, estramustine inhibited the association of MAPs with taxol microtubules. Turbidity (A350) studies further demonstrated that 20–60 microM-estramustine inhibited MAP-2-driven tubulin assembly and produced microtubule disassembly. Electron-microscopic studies confirmed the centrifugation and turbidity results. The data demonstrated that estramustine can bind MAPs and MAP-2 specifically, thereby inhibiting microtubule assembly.

Electron microscopic studies on the structure of motile primordial germ cells of Xenopus laevis in vitro

Development ◽  
1978 ◽  
Vol 46 (1) ◽  
pp. 119-133
Author(s):  
Janet Heasman ◽  
C. C. Wylie
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Structural Features ◽  
Culture Conditions ◽  
Structural Basis ◽  
Electron Microscopic ◽  
Microscopic Studies

Primordial germ cells (PGCs) of Xenopus laevis have been isolated from early embryos and kept alive in vitro, in order to study the structural basis of their motility, using the transmission and scanning electron microscope. The culture conditions used mimicked as closely as possible the in vivo environment of migrating PGCs, in that isolated PGCs were seeded onto monolayers of amphibian mesentery cells. In these conditions we have demonstrated that: (a) No significant differences were found between the morphology of PGCs in vitro and in vivo. (b) Structural features involved in PGC movement in vitro include (i) the presence of a filamentous substructure, (ii) filopodial and blunt cell processes, (iii) cell surface specializations. These features are also characteristic of migratory PGCs studied in vivo. (c) PGCs in vitro have powers of invasion similar to those of migrating PGCs in vivo. They occasionally become completely surrounded by cells of the monolayer and, in this situation, bear striking resemblance to PGCs moving between mesentery cells to the site of the developing gonad in stage-44 tadpoles. We conclude that as far as it is possible to assess, the behaviour of isolated PGCs in these in vitro conditions mimics their activities in vivo. This allows us to study the ultrastructural basis of their migration.

scholarly journals Myosin VI: cellular functions and motor properties

2004 ◽  
Vol 359 (1452) ◽  
pp. 1931-1944 ◽  
Author(s):  
K. C. Holmes ◽  
D. R. Trentham ◽  
R. Simmons ◽  
Rhys Roberts ◽  
Ida Lister ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Leading Edge ◽  
Force Transducer ◽  
Myosin Vi ◽  
Cellular Functions ◽  
Electron Microscopic ◽  
Coated Pits ◽  
Microscopic Studies ◽  
Golgi Network

Myosin VI has been localized in membrane ruffles at the leading edge of cells, at the trans–Golgi network compartment of the Golgi complex and in clathrin–coated pits or vesicles, indicating that it functions in a wide variety of intracellular processes. Myosin VI moves along actin filaments towards their minus end, which is the opposite direction to all of the other myosins so far studied (to our knowledge), and is therefore thought to have unique properties and functions. To investigate the cellular roles of myosin VI, we identified various myosin VI binding partners and are currently characterizing their interactions within the cell. As an alternative approach, we have expressed and purified full–length myosin VI and studied its in vitro properties. Previous studies assumed that myosin VI was a dimer, but our biochemical, biophysical and electron microscopic studies reveal that myosin VI can exist as a stable monomer. We observed, using an optical tweezers force transducer, that monomeric myosin VI is a non–processive motor which, despite a relatively short lever arm, generates a large working stroke of 18 nm. Whether monomer and/or dimer forms of myosin VI exist in cells and their possible functions will be discussed.

scholarly journals Accelerated myeloblast destruction and abnormal lysosome disruption in cultured bone marrow: association with indolent acute myelogenous leukemia

Blood ◽  
1976 ◽  
Vol 48 (1) ◽  
pp. 23-32 ◽  
Author(s):  
RF Branda ◽  
HS Jacob ◽  
SD Douglas ◽  
CF Moldow ◽  
RR Puumala
Keyword(s):  
Bone Marrow ◽  
Acute Myelogenous Leukemia ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
Electron Microscopic ◽  
Granule Formation ◽  
Microscopic Studies ◽  
Acute Myelogenous ◽  
Primary Granules

Abstract Despite no chemotherapy and a marrow morphologically typical of frank relapse, an acute myelogenous leukemia (AML) patient survived for nearly 1 yr. During this time she remained asymptomatic and maintained nearly normal levels of platelets and hemoglobin. Cytochemical and electron microscopic studies of her bone marrow in liquid culture revealed on several occasions a unique maturational sequence in that leukemic cells differentiated to form morphologically abnormal primary granules which appeared to rupture and cause cytolysis of these cells. In these cultures, blasts rapidly disappeared and were replaced by more mature granulocytes, in contrast to observations in cultures derived from five other patients with AML in relapse which showed persistently elevated blast counts with no evidence of maturation in vitro. These findings support the concept that in AML cell maturation is regularly impaired and in some cases also aberrant. In addition, the abnormal granule formation with autolysis of the leukemic cells observed in one patient may explain both the early cell death in vitro and this patient's relatively indolent clinical course. Similar in vitro studies may help predict atypical clinical courses in patients with AML and facilitate design of appropriate chemotherapy.

scholarly journals Platelet Satellitism

Blood ◽  
1974 ◽  
Vol 43 (6) ◽  
pp. 831-836 ◽  
Author(s):  
Carl R. Kjeldsberg ◽  
John Swanson
Keyword(s):  
Polymorphonuclear Leukocytes ◽  
Plasma Membranes ◽  
Clinical Importance ◽  
Electron Microscopic ◽  
Normal Platelet ◽  
Microscopic Studies ◽  
Platelet Satellitism ◽  
Platelet Functions

Abstract Platelet adherence to polymorphonuclear leukocytes, or so-called platelet satellitism, has, to our knowledge, been reported in only four patients. We had the opportunity to study this phenomenon in two patients. Platelet satellitism was only seen in EDTA anticoagulated blood, and the platelets were seen to surround polymorphonuclear leukocytes only. Electron microscopic studies demonstrated focally opposed regions of platelet and neutrophil plasma membranes. Phagocytosis of platelets was also observed. In vivo and in vitro platelet functions were normal. Platelet satellitism is an in vitro phenomenon, the cause of which is unknown. We are unable to relate it to functional abnormalitles of the blood, the clinical condition of the patient, or to drugs. This phenomenon has some clinical importance in that it causes spurious thrombocytopenia.

Structural and functional study of control of canine tracheal smooth muscle

1980 ◽  
Vol 238 (1) ◽  
pp. C27-C33 ◽  
Author(s):  
M. S. Kannan ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Electrical Field Stimulation ◽  
Sympathetic Nerves ◽  
Tracheal Smooth Muscle ◽  
Functional Study ◽  
Field Stimulation ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
Stimulation Of

The structural bases for myogenic and neurogenic control of canine tracheal smooth muscle were studied. At optimum lengths, strips of muscle showed insignificant neurogenic or myogenic tone. Atropine and/or tetrodotoxin blocked the contractile responses elicited on electrical field stimulation of intrinsic nerves. After raising the tone with tetraethylammonium ion and in the presence of atropine, field stimulation of nerves caused a relaxation, a major component of which was blocked by propranolol and/or tetrodotoxin, suggesting an effect mediated through interaction of mediator released from sympathetic nerves with beta-adrenergic receptors. Electron microscopic studies revealed gap junctions between extensions of smooth-muscle cells and a sparse innervation. The axonal varicosities, corresponding to cholinergic (predominantly) and adrenergic (occasionally) nerves, were seen predominantly in the clefts between cell bundles. The physiological responses were compared with the morphological features. Although this muscle exhibits multiunit behavior in vitro, implying that nerves initiate the coordinate activity, its ultrastructural features suggest a potential for single-unit behavior.

scholarly journals EFFECT OF ACTIVE ACCUMULATION OF CALCIUM AND PHOSPHATE IONS ON THE STRUCTURE OF RAT LIVER MITOCHONDRIA

1964 ◽  
Vol 23 (1) ◽  
pp. 21-38 ◽  
Author(s):  
John W. Greenawalt ◽  
Carlo S. Rossi ◽  
Albert L. Lehninger
Keyword(s):  
Specific Gravity ◽  
Rat Liver ◽  
Cesium Chloride ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Electron Microscopic ◽  
Dense Granules ◽  
Phosphate Ions ◽  
Microscopic Studies

Rat liver mitochondria allowed to accumulate maximal amounts of Ca++ and HPO4= ions from the suspending medium in vitro during respiration have a considerably higher specific gravity than normal mitochondria and may be easily separated from the latter by isopycnic centrifugation in density gradients of sucrose or cesium chloride. When the mitochondria are allowed to accumulate less than maximal amounts of Ca++ and HPO4= from the medium, they have intermediate specific gravities which are roughly proportional to their content of calcium phosphate. Maximally "loaded" mitochondria are relatively homogeneous with respect to specific gravity. Correlated biochemical and electron microscopic studies show that Ca++-loaded mitochondria contain numerous dense granules, of which some 85 per cent are over 500 A in diameter. These granules are electron-opaque not only following fixation and staining with heavy metal reagents, but also following fixation with formaldehyde, demonstrating that the characteristic granules in Ca++-loaded mitochondria have intrinsic electron-opacity. The dense granules are almost always located within the inner compartment of the mitochondria and not in the space between the inner and outer membranes. They are frequently located at or near the cristae and they often show electron-transparent "cores." Such granules appear to be made up of clusters of smaller dense particles, but preliminary x-ray diffraction analysis and electron diffraction studies have revealed no evidence of crystallinity in the deposits. The electron-opaque granules decrease in number when the Ca++-loaded mitochondria are incubated with 2,4-dinitrophenol; simultaneously there is discharge of Ca++ and phosphate from the mitochondria into the medium.

scholarly journals A trypsin-sensitive receptor on membrane vesicles is required for nuclear envelope formation in vitro.

1988 ◽  
Vol 107 (1) ◽  
pp. 57-68 ◽  
Author(s):  
K L Wilson ◽  
J Newport
Keyword(s):  
Nuclear Envelope ◽  
Protein Interactions ◽  
Membrane Vesicles ◽  
Integral Membrane Protein ◽  
Electron Microscopic ◽  
Vitro Assay ◽  
Nuclear Envelope Assembly ◽  
Microscopic Studies ◽  
Nuclear Envelope Formation

The reformation of functioning organelles at the end of mitosis presents a problem in vesicle targeting. Using extracts made from Xenopus laevis frog eggs, we have studied in vitro the vesicles that reform the nuclear envelope. In the in vitro assay, nuclear envelope growth is linear with time. Furthermore, the final surface area of the nuclear envelopes formed is directly dependent upon the amount of membrane vesicles added to the assay. Egg membrane vesicles could be fractionated into two populations, only one of which was competent for nuclear envelope assembly. We found that vesicles active in nuclear envelope assembly contained markers (BiP and alpha-glucosidase II) characteristic of the endoplasmic reticulum (ER), but that the majority of ER-derived vesicles do not contribute to nuclear envelope size. This functional distinction between nuclear vesicles and ER-derived vesicles implies that nuclear vesicles are unique and possess at least one factor required for envelope assembly that is lacking in other vesicles. Consistent with this, treatment of vesicles with trypsin destroyed their ability to form a nuclear envelope; electron microscopic studies indicate that the trypsin-sensitive proteins is required for vesicles to bind to chromatin. However, the protease-sensitive component(s) is resistant to treatments that disrupt protein-protein interactions, such as high salt, EDTA, or low ionic strength solutions. We propose that an integral membrane protein, or protein tightly associated with the membrane, is critical for nuclear vesicle targeting or function.

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