scholarly journals Electrophysiological and Morphological Identification of Action Potential Generating Secretory Cell Types Isolated from the Salivary Gland of Ariolimax

1983 ◽  
Vol 102 (1) ◽  
pp. 13-23 ◽  
Author(s):  
JAMES M. GOLDRING ◽  
JOANNE W. KATER ◽  
STANLEY B. KATER
Keyword(s):  
Electrical Activity ◽  
Granule Cell ◽  
Rise Time ◽  
Action Potentials ◽  
Cell Types ◽  
Cell Type ◽  
Inward Current ◽  
Distinct Cell ◽  
Delayed Rectification ◽  
Granule Diameter

The salivary glands of the terrestrial slug, Ariolimax, are composed of several morphologically distinct cell types which are observable in thin pieces of living glands and in sectioned tissue viewed with the light or electron microscope. ‘Blind’ penetration via microelectrode into the gland reveals different classes of electrical activity including: (1) cells with fast action potentials; (2) cells with slow action potentials; and (3) cells with large resting potentials but which display only delayed rectification. After isolation of cells by enzymatic dissociation we could electrophysiologically characterize individual cell types and relate these to cell types identified morphologically in the living gland and under the light and electron microscopes. Microelectrode recordings from identified cell types have demonstrated: (1) the large granule cell type (granule diameter = 8–12μm) displays a characteristic long duration, slow rise time action potential whose inward current is primarily carried by Ca2+; (2) the medium granule cell type (granule diameter = 3--6 μm) displays only delayed rectification and (3) the small granule cell type (granule diameter = 1–2μm) displays fast rise time, short duration action potentials whose inward current is also carried primarily by Ca2+ ions. The finding that morphologically distinct cell types display distinct electrical activity may indicate that different secretory products are released only under a specific set of conditions associated with changes in membrane potential.

scholarly journals Independent glial subtypes delay development and extend healthy lifespan upon reduced insulin-PI3K signalling

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Nathaniel S. Woodling ◽  
Arjunan Rajasingam ◽  
Lucy J. Minkley ◽  
Alberto Rizzo ◽  
Linda Partridge
Keyword(s):  
Glial Cell ◽  
Cell Types ◽  
Therapeutic Interventions ◽  
Developmental Timing ◽  
Cell Type ◽  
Specific Effects ◽  
Trade Offs ◽  
Distinct Cell ◽  
Pi3k Signalling ◽  
Cell Type Specific

Abstract Background The increasing age of global populations highlights the urgent need to understand the biological underpinnings of ageing. To this end, inhibition of the insulin/insulin-like signalling (IIS) pathway can extend healthy lifespan in diverse animal species, but with trade-offs including delayed development. It is possible that distinct cell types underlie effects on development and ageing; cell-type-specific strategies could therefore potentially avoid negative trade-offs when targeting diseases of ageing, including prevalent neurodegenerative diseases. The highly conserved diversity of neuronal and non-neuronal (glial) cell types in the Drosophila nervous system makes it an attractive system to address this possibility. We have thus investigated whether IIS in distinct glial cell populations differentially modulates development and lifespan in Drosophila. Results We report here that glia-specific IIS inhibition, using several genetic means, delays development while extending healthy lifespan. The effects on lifespan can be recapitulated by adult-onset IIS inhibition, whereas developmental IIS inhibition is dispensable for modulation of lifespan. Notably, the effects we observe on both lifespan and development act through the PI3K branch of the IIS pathway and are dependent on the transcription factor FOXO. Finally, IIS inhibition in several glial subtypes can delay development without extending lifespan, whereas the same manipulations in astrocyte-like glia alone are sufficient to extend lifespan without altering developmental timing. Conclusions These findings reveal a role for distinct glial subpopulations in the organism-wide modulation of development and lifespan, with IIS in astrocyte-like glia contributing to lifespan modulation but not to developmental timing. Our results enable a more complete picture of the cell-type-specific effects of the IIS network, a pathway whose evolutionary conservation in humans make it tractable for therapeutic interventions. Our findings therefore underscore the necessity for cell-type-specific strategies to optimise interventions for the diseases of ageing.

CHANGES IN ADENOHYPOPHYSEAL CYTOLOGY AND NUCLEIC ACID CONTENT IN THE RAT 32 DAYS AFTER BILATERAL ADRENALECTOMY AND THE CHRONIC INJECTION OF CORTISOL

1967 ◽  
Vol 45 (6) ◽  
pp. 947-956 ◽  
Author(s):  
Jacob Kraicer ◽  
Marc Herlant ◽  
Pierre Duclos
Keyword(s):  
Cell Types ◽  
Bilateral Adrenalectomy ◽  
Synthetic Activity ◽  
Nucleic Acid Content ◽  
Cell Type ◽  
Cytological Evidence ◽  
Histological Techniques ◽  
Dna And Rna ◽  
Distinct Cell ◽  
Chronic Injection

Control, adrenalectomized, and cortisol-treated rats were maintained under rigidly controlled conditions, and the adenohypophyses were examined histologically with two staining procedures which differentiate six distinct cell types. Only one cell type demonstrated cytological evidence of increased synthetic activity 32 days after adrenalectomy (the changes were, however, minimal) and decreased synthetic activity following the chronic injection of cortisol. This cell type, which we designate as the corticotroph, would be classed as a chromophobe (no stainable granules) with use of standard histological techniques, but is, in fact, as Herlant's Tetrachrome demonstrates, a distinct acidophilic cell type different from the prolactin cell and the somatotroph. The determination of adenohypophyseal DNA and RNA revealed no evidence of increased protein synthetic activity following bilateral adrenalectomy, but did reveal evidence of decreased protein synthetic activity following the chronic injection of cortisol.

scholarly journals A Radioautographic Study of Hemopoietic Repopulation Using Irradiated Parabiotic Rats

Blood ◽  
1966 ◽  
Vol 28 (6) ◽  
pp. 873-890 ◽  
Author(s):  
RUTH W. CAFFREY TYLER ◽  
N. B. EVERETT
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Lymph Nodes ◽  
Cell Lines ◽  
Cell Types ◽  
Cell Type ◽  
Distinct Cell ◽  
Major Cell Type

Abstract These radioautographic studies using parabiotic rats and partial marrow shielding showed that cells responsible for recovery of irradiated bone marrow had their origin in the shielded marrow. Three morphologically distinct cell types appeared in the blood of these parabionts, mature granulocytes, small lymphocytes and monocytoid cells. The monocytoid was the major cell type which crossed from the shielded to nonshielded marrow, and the observations suggested that it is this cell which served as a stem cell for both the erythrocytic and granulocytic cell lines. Labeled erythroblasts and myeloblasts were observed in the recovering marrow, and the labeling intensity of these cells indicated that they were the second or third division products of labeled immigrant cells. The effect of marrow shielding upon the recovery of lymphopoiesis in spleen, thymus, lymph nodes and bone marrow is also discussed.

Modulation of electrical activity by 5-hydroxytryptamine in crayfish neurosecretory cells.

1997 ◽  
Vol 200 (23) ◽  
pp. 3079-3090 ◽  
Author(s):  
F Sáenz ◽  
U García ◽  
U Aréchiga
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Procambarus Clarkii ◽  
Neurosecretory Cells ◽  
Slow Inward Current ◽  
Bathing Solution ◽  
Inward Current ◽  
Dose Dependent ◽  
Bursting Activity

The effect of 5-hydroxytryptamine (5-HT) was tested in a population of X organ neurosecretory cells in the eyestalk of the crayfish Procambarus clarkii. Tests were conducted both in situ and on isolated neurones kept in culture. The application of 5-HT induced action potentials in silent cells. In spontaneously active neurones, 5-HT increased the firing rate and either induced firing or enhanced bursting activity. The effect of 5-HT was dose-dependent within the range 1-100 micromol l-1 in cells of the intact organ. The effect persisted for 20-30 min after 5-HT had been removed from the bathing solution. Successive applications of 5-HT onto the same neurone reduced responsiveness, suggesting that desensitization had occurred. The effects of 5-HT were blocked by prior incubation with the 5-HT antagonist methysergide. In X organ cells whose axons and branches in the neuropile had been severed, 5-HT induced a depolarisation associated with a slow inward current. In X organ neurones isolated from the eyestalk and kept in culture, 5-HT was capable of evoking bursts of action potentials and elicited a slow inward current. This effect was also blocked by methysergide (10(-4 )mol l-1). These results suggest a direct modulatory effect of 5-HT on the pattern of electrical activity in the X organ cells.

Morphological study of the gut in Sagitta setosa, S. serratodentata and S. pacifica (Chaetognatha). Functional implications in digestive processes

1999 ◽  
Vol 79 (6) ◽  
pp. 1097-1109 ◽  
Author(s):  
Y. Perez ◽  
J. Arnaud ◽  
M. Brunet ◽  
J.-P. Casanova ◽  
J. Mazza
Keyword(s):  
Intestinal Epithelium ◽  
Morphological Study ◽  
Secretory Cell ◽  
Secretory Granules ◽  
Ciliated Cell ◽  
Posterior Part ◽  
Cell Types ◽  
Cell Type ◽  
Distinct Cell ◽  
Functional Implications

The study of the digestive epithelium in Sagitta setosa, S. serratodentata, and S. pacifica revealed only a few morphological and cytological differences among the three species. The gut was divided in two main regions. The first is the cephalic region where the epithelium is composed of three distinct cell types (S1, S2, and S3), the ultrastructure of which is probably specialized either for the synthesis of mucosubstances (S1), or enzymes (S3), or both (S2). The second region of the gut extends to the trunk and is mainly composed of the intestine and a short vertical rectum. No intestinal diverticula were observed. The intestinal epithelium displayed two ciliated cell types, anteriorly, a secretory cell type (S4) containing large mucus-like granules, and a second cell type (A) predominated in the posterior part of the intestine. A-cells appear to have two main functions. Although they exhibit secretory granules, they also display typical endocytotic features in their upper half, i.e. coated vesicles, a well-developed tubulo–vesicular network and two distinct types of digestive vacuoles corresponding to an endosome–lysosome-like system. From the distribution and presumed function of the cells, the gut may be divided in two main functional units, i.e. the cephalic and trunk units.

scholarly journals Biophysical Support for Functionally Distinct Cell Types in the Frontal Eye Field

2009 ◽  
Vol 101 (2) ◽  
pp. 912-916 ◽  
Author(s):  
Jeremiah Y. Cohen ◽  
Pierre Pouget ◽  
Richard P. Heitz ◽  
Geoffrey F. Woodman ◽  
Jeffrey D. Schall
Keyword(s):  
Action Potentials ◽  
Cell Types ◽  
Frontal Eye Field ◽  
Subcortical Structures ◽  
Brain Areas ◽  
Visual Neurons ◽  
Distinct Cell ◽  
Eye Field ◽  
And Function ◽  
Different Cell Types

Numerous studies have described different functional cell types in the frontal eye field (FEF), but the reliability of the distinction between these types has been uncertain. Studies in other brain areas have described specific differences in the width of action potentials recorded from different cell types. To substantiate the functionally defined cell types encountered in FEF, we measured the width of spikes of visual, movement, and visuomovement types of FEF neurons in macaque monkeys. We show that visuomovement neurons had the thinnest spikes, consistent with a role in local processing. Movement neurons had the widest spikes, consistent with their role in sending eye movement commands to subcortical structures such as the superior colliculus. Visual neurons had wider spikes than visuomovement neurons, consistent with their role in receiving projections from occipital and parietal cortex. These results show how structure and function of FEF can be linked to guide inferences about neuronal architecture.

scholarly journals Functional identification of islet cell types by electrophysiological fingerprinting

2017 ◽  
Vol 14 (128) ◽  
pp. 20160999 ◽  
Author(s):  
Linford J. B. Briant ◽  
Quan Zhang ◽  
Elisa Vergari ◽  
Joely A. Kellard ◽  
Blanca Rodriguez ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Islet Cell ◽  
Cell Types ◽  
Cell Type ◽  
Functional Identification ◽  
Large Dataset ◽  
Intact Mouse ◽  
Whole Cell Patch Clamp ◽  
Mouse Islets ◽  
Islet Cell Types

The α-, β- and δ-cells of the pancreatic islet exhibit different electrophysiological features. We used a large dataset of whole-cell patch-clamp recordings from cells in intact mouse islets ( N = 288 recordings) to investigate whether it is possible to reliably identify cell type (α, β or δ) based on their electrophysiological characteristics. We quantified 15 electrophysiological variables in each recorded cell. Individually, none of the variables could reliably distinguish the cell types. We therefore constructed a logistic regression model that included all quantified variables, to determine whether they could together identify cell type. The model identified cell type with 94% accuracy. This model was applied to a dataset of cells recorded from hyperglycaemic βV59M mice; it correctly identified cell type in all cells and was able to distinguish cells that co-expressed insulin and glucagon. Based on this revised functional identification, we were able to improve conductance-based models of the electrical activity in α-cells and generate a model of δ-cell electrical activity. These new models could faithfully emulate α- and δ-cell electrical activity recorded experimentally.

scholarly journals A Reference-free Approach for Cell Type Classification with scRNA-seq

2021 ◽  
Author(s):  
Qi Sun ◽  
YIFAN PENG ◽  
Jinze Liu
Keyword(s):  
State Of The Art ◽  
Cell Types ◽  
Rna Seq ◽  
Cell Type ◽  
Current Version ◽  
Expression Of Genes ◽  
Distinct Cell ◽  
Alignment Process ◽  
Efficient Alternative ◽  
Type Classification

The single-cell RNA sequencing (scRNA-seq) has become a revolutionary technology to detect and characterize distinct cell populations under different biological conditions. Unlike bulk RNA-seq, the expression of genes from scRNA-seq is highly sparse due to limited sequencing depth per cell. This is worsened by tossing away a significant portion of reads that cannot be mapped during gene quantification. To overcome data sparsity and fully utilize original sequences, we propose scSimClassify, a reference-free and alignment-free approach to classify cell types with k-mer level features derived from raw reads in a scRNA-seq experiment. The major contribution of scSimClassify is the simhash method compressing k-mers with similar abundance profiles into groups. The compressed k-mer groups (CKGs) serve as the aggregated k-mer level features for cell type classification. We evaluate the performance of CKG features for predicting cell types in four scRNA-seq datasets comparing four state-of-the-art classification methods as well as two scRNA-seq specific algorithms. Our experiments demonstrate that the CKG features lend themselves to better performance than traditional gene expression features in scRNA-seq classification accuracy in the majority of cases. Because CKG features can be efficiently derived from raw reads without a resource-intensive alignment process, scSimClassify offers an efficient alternative to help scientists rapidly classify cell types without relying on reference sequences. The current version of scSimClassify is implemented in python and can be found at https://github.com/digi2002/scSimClassify.

scholarly journals Structure and mechanism of SARS-CoV-2 Spike N679-V687 deletion variant elucidate cell-type specific evolution of viral fitness

2021 ◽  
Author(s):  
Kapil Gupta ◽  
Christine Toelzer ◽  
Maia Kavanagh Williamson ◽  
Deborah Shoemark ◽  
A. Sofia F. Oliveira ◽  
...  
Keyword(s):  
Cell Types ◽  
Viral Fitness ◽  
Cell Tropism ◽  
Cell Type ◽  
Amino Acid Deletion ◽  
Recognition Motif ◽  
Mechanistic Insight ◽  
Distinct Cell ◽  
Cell Type Specific ◽  
Insight Into

As the global burden of SARS-CoV-2 infections escalates, so does the evolution of viral variants which is of particular concern due to their potential for increased transmissibility and pathology. In addition to this entrenched variant diversity in circulation, RNA viruses can also display genetic diversity within single infected hosts with co-existing viral variants evolving differently in distinct cell types. The BriSΔ variant, originally identified as a viral subpopulation by passaging SARS-CoV-2 isolate hCoV-19/England/02/2020, comprises in the spike glycoprotein an eight amino-acid deletion encompassing the furin recognition motif and S1/S2 cleavage site. Here, we analyzed the structure, function and molecular dynamics of this variant spike, providing mechanistic insight into how the deletion correlates to viral cell tropism, ACE2 receptor binding and infectivity, allowing the virus to probe diverse trajectories in distinct cell types to evolve viral fitness.

scholarly journals A probabilistic gene expression barcode for annotation of cell-types from single cell RNA-seq data

2020 ◽  
Author(s):  
Isabella N. Grabski ◽  
Rafael A. Irizarry
Keyword(s):  
Gene Expression ◽  
Single Cell ◽  
Latent Variable ◽  
Cell Types ◽  
Marker Genes ◽  
Cell Type ◽  
Variable Model ◽  
Distinct Cell Type ◽  
Distinct Cell ◽  
Public Datasets

AbstractSingle-cell RNA sequencing (scRNA-seq) quantifies gene expression for individual cells in a sample, which allows distinct cell-type populations to be identified and characterized. An important step in many scRNA-seq analysis pipelines is the annotation of cells into known cell-types. While this can be achieved using experimental techniques, such as fluorescence-activated cell sorting, these approaches are impractical for large numbers of cells. This motivates the development of data-driven cell-type annotation methods. We find limitations with current approaches due to the reliance on known marker genes or from overfitting because of systematic differences between studies or batch effects. Here, we present a statistical approach that leverages public datasets to combine information across thousands of genes, uses a latent variable model to define cell-type-specific barcodes and account for batch effect variation, and probabilistically annotates cell-type identity. The barcoding approach also provides a new way to discover marker genes. Using a range of datasets, including those generated to represent imperfect real-world reference data, we demonstrate that our approach substantially outperforms current reference-based methods, in particular when predicting across studies. Our approach also demonstrates that current approaches based on unsupervised clustering lead to false discoveries related to novel cell-types.

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