scholarly journals Visualization of a Cytoskeleton-like Ftsz Network in Chloroplasts

2000 ◽  
Vol 151 (4) ◽  
pp. 945-950 ◽  
Author(s):  
Justine Kiessling ◽  
Sven Kruse ◽  
Stefan A. Rensing ◽  
Klaus Harter ◽  
Eva L. Decker ◽  
...  
Keyword(s):  
Life Sciences ◽  
Dependent Manner ◽  
Bacterial Cell Division ◽  
Subcellular Structure ◽  
Form And Function ◽  
Intron Structure ◽  
Division Process ◽  
Eukaryotic Organisms ◽  
And Function ◽  
Dose Dependent

It has been a long-standing dogma in life sciences that only eukaryotic organisms possess a cytoskeleton. Recently, this belief was questioned by the finding that the bacterial cell division protein FtsZ resembles tubulin in sequence and structure and, thus, may be the progenitor of this major eukaryotic cytoskeletal element. Here, we report two nuclear-encoded plant ftsZ genes which are highly conserved in coding sequence and intron structure. Both their encoded proteins are imported into plastids and there, like in bacteria, they act on the division process in a dose-dependent manner. Whereas in bacteria FtsZ only transiently polymerizes to a ring-like structure, in chloroplasts we identified persistent, highly organized filamentous scaffolds that are most likely involved in the maintenance of plastid integrity and in plastid division. As these networks resemble the eukaryotic cytoskeleton in form and function, we suggest the term “plastoskeleton” for this newly described subcellular structure.

Life and Death in Paris

2016 ◽  
Author(s):  
Leon Chai
Keyword(s):  
Empirical Study ◽  
Medical Science ◽  
Life Sciences ◽  
Generative Capacity ◽  
Promising Candidate ◽  
Romantic Period ◽  
Life And Death ◽  
Form And Function ◽  
And Function ◽  
Century Science

This chapter charts the debates in the Romantic period on medicine and its related life sciences. Medicine seemed the most promising candidate to generate advances; or, at least, the rationalization of the vital by medical science could be taken further than by other sciences. The more empirical study of uniquely vital process in Paris would yield more results than the formally more direct but methodologically immature confrontation of the vital by Paris’s main rival, Montpellier. Paris maintained controversy within its own approach, and medicine had to reconcile competing hierarchies of form and function. Nonetheless, it was the generative capacity of these initiatives that made what we call nineteenth-century science possible. And that, you might say, was their Romantic legacy.

Protective Effect of Pantethine on Experimental Thrombocytopenia in the Rat

1975 ◽  
Vol 33 (03) ◽  
pp. 528-539 ◽  
Author(s):  
Shin-ichiro Ashida ◽  
Yasushi Abiko
Keyword(s):  
Nitrogen Mustard ◽  
Experimental Period ◽  
Significant Degree ◽  
Rabbit Serum ◽  
Dependent Manner ◽  
Essentially Normal ◽  
And Function ◽  
Dose Dependent ◽  
Platelet Functions

SummaryThe effects of pantethine on circulating platelet counts and platelet functions were studied in normal and experimentally produced thrombocytopenic rats.Administration of pantethine to normal animals did not cause any alterations in both platelet count and function except for a slight enhancement of intravascular platelet aggregation induced by collagen or neuraminidase.Injection of anti-rat platelet rabbit serum into rats resulted in acute thrombocytopenia. Administration of pantethine prior to the antiserum promoted recovery from the thrombocytopenia in a dose dependent manner, but administration of the drug after development of the thrombocytopenia was not effective. A similar result was obtained with a transient thrombocytopenia induced by exchange transfusion with platelet poor blood. Regardless of whether animals were treated with pantethine or not, the platelets newly generated during the course of recovery from thrombocytopenia were essentially normal in the function tested in vitro.A more chronic thrombocytopenia induced by repeated injections of the antiserum was prevented, to some significant degree, by daily administration of pantethine throughout the experimental period.In contrast to these, such effect of pantethine was not observed with the thrombocytopenia models produced by nitrogen mustard N-oxide and neuraminidase.These findings were discussed in relation to mechanism of the action of pantethine and to possible clinical application of the drug to thrombocytopenia.

scholarly journals Spontaneous and glucocorticoid-induced apoptosis in human mature T lymphocytes

Blood ◽  
1995 ◽  
Vol 86 (11) ◽  
pp. 4199-4205 ◽  
Author(s):  
M Brunetti ◽  
N Martelli ◽  
A Colasante ◽  
M Piantelli ◽  
P Musiani ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Interleukin 2 ◽  
Cell Number ◽  
T Cell Subsets ◽  
Dependent Manner ◽  
Cell Repertoire ◽  
Induced Apoptosis ◽  
And Function ◽  
Dose Dependent

Glucocorticoid (GC)-induced apoptosis is a well-recognized physiologic regulator of murine T-cell number and function. We have analyzed its mechanisms in human mature T cells, which have been thought to be insensitive until recently. Peripheral blood T cells showed sensitivity to GC-induced apoptosis soon after the proliferative response to a mitogenic stimulation, and were also sensitive to spontaneous (ie, growth factor deprivation-dependent) apoptosis. CD8+ T cells were more sensitive to both forms than CD4+ T cells. Acquisition of sensitivity to GC-induced apoptosis was not associated with any change in number or affinity of GC receptors. Both spontaneous and GC-induced apoptosis were increased by the macromolecular synthesis inhibitors, cycloheximide (CHX) and puromycin. A positive correlation between the degree of protein synthesis inhibition and the extent of apoptosis was observed. Interleukin-2 (IL-2) IL-4, and IL-10 protected (IL-2 > IL-10 > IL-4) T cells from both forms of apoptosis in a dose-dependent manner. Our data suggest that spontaneous and GC-induced apoptosis regulate the human mature T-cell repertoire by acting early after the immune response and differentially affecting T-cell subsets.

scholarly journals Bisphenol A Modifies the Regulation Exerted by Testosterone on 5α-Reductase Isozymes in Ventral Prostate of Adult Rats

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Pilar Sánchez ◽  
Beatriz Castro ◽  
Jesús M. Torres ◽  
Asunción Olmo ◽  
Raimundo G. del Moral ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Prostate Gland ◽  
Ventral Prostate ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Adult Rats ◽  
Short Term Exposure ◽  
Rat Prostate ◽  
And Function ◽  
Dose Dependent

The development, growth, and function of the prostate gland depend on androgen stimulation. The primary androgen in prostate is 5α-dihydrotestosterone (DHT) which is synthesized from circulating testosterone (T) through the action of 5α-reductase (5α-R). Although 5α-R occurs as five isozymes, only 5α-R1 and 5α-R2 are physiologically involved in steroidogenesis. The endocrine disruptor bisphenol A (BPA) alters sexual organs, including the prostate. Our previous findings indicated that BPA decreased the expression of 5α-R1 and 5α-R2 in rat prostate but also circulating T. Thus, it is unclear whether BPA exerts this effect on 5α-R isozymes by reducing circulating T or by any other mechanism. In this study, we examine the effects of short-term exposure to BPA at doses below 25 μg/Kg/d and above 300 μg/Kg/d of the TDI on mRNA levels of 5α-R1 and 5α-R2 in prostate of adult castrated rats supplemented with T to achieve constant circulating T levels. mRNA levels were measured by absolute quantitative RT-PCR, T levels by RIA, and DHT levels by ELISA. Our results indicated that in castrated rats treated with T BPA at the two doses studied significantly decreased the mRNA levels of both 5α-R isozymes in a dose-dependent manner without modifications in circulating T.

Elevated carbon dioxide upregulates NBCn1 Na+/HCO3− cotransporter in human embryonic kidney cells

2013 ◽  
Vol 305 (12) ◽  
pp. F1765-F1774 ◽  
Author(s):  
Alejandro Orlowski ◽  
Lorena A. Vargas ◽  
Ernesto A. Aiello ◽  
Bernardo V. Álvarez
Keyword(s):  
Cell Types ◽  
Recovery Phase ◽  
Kidney Cells ◽  
Dependent Manner ◽  
Human Embryonic Kidney ◽  
Human Embryonic Kidney Cells ◽  
Hek Cells ◽  
And Function ◽  
Acid Loading ◽  
Dose Dependent

The NBCn1 Na+/HCO3− cotransporter catalyzes the electroneutral movement of 1 Na+:1 HCO3− into kidney cells. We characterized the intracellular pH (pHi) regulation in human embryonic kidney cells (HEK) subjected to NH4Cl prepulse acid loading, and we examined the NBCn1 expression and function in HEK cells subjected to 24-h elevated Pco2 (10–15%). After acid loading, in the presence of HCO3−, ∼50% of the pHi recovery phase was blocked by the Na+/H+ exchanger inhibitors EIPA (10–50 μM) and amiloride (1 mM) and was fully cancelled by 30 μM EIPA under nominally HCO3−-free conditions. In addition, in the presence of HCO3−, pHi recovery after acid loading was completely blocked when Na+ was omitted in the buffer. pHi recovery after acidification in HEK cells was repeated in the presence of the NBC inhibitor S0859, and the pHi recovery was inhibited by S0859 in a dose-dependent manner ( Ki = 30 μM, full inhibition at 60 μM), which confirmed NBC Na+/HCO3− cotransporter activation. NBCn1 expression increased threefold after 24-h exposure of cultured HEK cells to 10% CO2 and sevenfold after exposure to 15% CO2, examined by immunoblots. Finally, exposure of HEK cells to high CO2 significantly increased the HCO3−-dependent recovery of pHi after acid loading. We conclude that HEK cells expressed the NBCn1 Na+/HCO3− cotransporter as the only HCO3−-dependent mechanism responsible for cellular alkaline loading. NBCn1, which expresses in different kidney cell types, was upregulated by 24-h high-Pco2 exposure of HEK cells, and this upregulation was accompanied by increased NBCn1-mediated HCO3− transport.

scholarly journals Sites of vulnerability on ricin B chain revealed through epitope mapping of toxin-neutralizing monoclonal antibodies

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0236538
Author(s):  
David J. Vance ◽  
Amanda Y. Poon ◽  
Nicholas J. Mantis
Keyword(s):  
Monoclonal Antibodies ◽  
Mammalian Cells ◽  
Type I ◽  
Dependent Manner ◽  
Type Ii ◽  
Single Chain ◽  
Carbohydrate Recognition Domains ◽  
And Function ◽  
Golgi Network ◽  
Dose Dependent

Ricin toxin’s B subunit (RTB) is a multifunctional galactose (Gal)-/N-acetylgalactosamine (GalNac)-specific lectin that promotes uptake and intracellular trafficking of ricin’s ribosome-inactivating subunit (RTA) into mammalian cells. Structurally, RTB consists of two globular domains (RTB-D1, RTB-D2), each divided into three homologous sub-domains (α, β, γ). The two carbohydrate recognition domains (CRDs) are situated on opposite sides of RTB (sub-domains 1α and 2γ) and function non-cooperatively. Previous studies have revealed two distinct classes of toxin-neutralizing, anti-RTB monoclonal antibodies (mAbs). Type I mAbs, exemplified by SylH3, inhibit (~90%) toxin attachment to cell surfaces, while type II mAbs, epitomized by 24B11, interfere with intracellular toxin transport between the plasma membrane and the trans-Golgi network (TGN). Localizing the epitopes recognized by these two classes of mAbs has proven difficult, in part because of RTB’s duplicative structure. To circumvent this problem, RTB-D1 and RTB-D2 were expressed as pIII fusion proteins on the surface of filamentous phage M13 and subsequently used as “bait” in mAb capture assays. We found that SylH3 captured RTB-D1 (but not RTB-D2) in a dose-dependent manner, while 24B11 captured RTB-D2 (but not RTB-D1) in a dose-dependent manner. We confirmed these domain assignments by competition studies with an additional 8 RTB-specific mAbs along with a dozen a single chain antibodies (VHHs). Collectively, these results demonstrate that type I and type II mAbs segregate on the basis of domain specificity and suggest that RTB’s two domains may contribute to distinct steps in the intoxication pathway.

scholarly journals The TRIM9/TRIM67 neuronal interactome reveals novel activators of morphogenesis

2020 ◽  
Author(s):  
Shalini Menon ◽  
Dennis Goldfarb ◽  
Tsungyo Ho ◽  
Erica W. Cloer ◽  
Nicholas P. Boyer ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Hippocampal Neurons ◽  
Spatial Learning And Memory ◽  
Dependent Manner ◽  
Synaptic Regulation ◽  
Form And Function ◽  
Guidance Cue ◽  
And Function ◽  
Trim Proteins ◽  
Protein Transporters

ABSTRACTTRIM9 and TRIM67 are neuronally-enriched E3 ubiquitin ligases essential for appropriate morphogenesis of cortical and hippocampal neurons and fidelitous responses to the axon guidance cue netrin-1. Deletion of murine Trim9 or Trim67 results in neuroanatomical defects and striking behavioral deficits, particularly in spatial learning and memory. TRIM9 and TRIM67 interact with cytoskeletal and exocytic proteins, but the full interactome is not known. Here we performed the unbiased proximity-dependent biotin identification (BioID) approach to define TRIM9 and TRIM67 protein-protein proximity network in developing cortical neurons and identified neuronal putative TRIM interaction partners. Candidates included cytoskeletal regulators, cytosolic protein transporters, exocytosis and endocytosis regulators, and proteins necessary for synaptic regulation. A subset of high priority candidates was validated, including Myo16, Coro1A, SNAP47, ExoC1, GRIP1, PRG-1, and KIF1A. For a subset of validated candidates, we utilized TIRF microscopy to demonstrate dynamic colocalization with TRIM proteins at the axonal periphery, including at the tips of filopodia. Further analysis demonstrated the RNAi-based knockdown of the unconventional myosin Myo16 in cortical neurons altered axonal branching patterns in a TRIM9 and netrin-1 dependent manner. Future analysis of other validated candidates will likely identify novel proteins and mechanisms by which TRIM9 and TRIM67 regulate neuronal form and function.

Serotonin and MAOA enable the organizer and tip dominance in Dictyostelium

2021 ◽  
Author(s):  
Ramamurthy Baskar ◽  
Rakesh Mani ◽  
Geoffrey Hyde
Keyword(s):  
Cell Adhesion ◽  
Rna Interference ◽  
Molecular Techniques ◽  
Monoamine Oxidase A ◽  
Dependent Manner ◽  
Serotonin Antagonist ◽  
And Function ◽  
Tip Formation ◽  
Dose Dependent ◽  
Specific Inhibitors

Abstract The embryonic organizer is essential to determine one or more developmental polarities during chordate early development1,2. Functionally similar organizers also occur in more ancient animals3, and even in some protozoans such as Dictyostelium, in which the tip of the multicellular mound acts as an organizer4, establishing the main developmental axis, and regulating the size of the fruiting body5. However, our understanding of how the Dictyostelium organizer arises, and functions, is limited. Here we show that monoamine oxidase A (maoA), which degrades serotonin, confers the fate of an organizer to the Dictyostelium tip. Conversely, once a tip has formed, serotonin contributes to tip dominance. It inhibits further tip formation, and thus ensures the mound retains the size specified during an earlier developmental stage. Reducing the expression of maoA through RNA interference or by adding MAO specific inhibitors suppresses tip formation. Conversely, adding human MAOA enzyme, or an antagonist or antibodies against serotonin, restores tip formation in maoA knockdowns. Overexpression of maoA or adding a serotonin antagonist to the wildtype induces multiple tips from a single mound in a dose dependent manner. Using an array of genetic and molecular techniques, we show that serotonin’s inhibition of cAMP signalling and cell-cell adhesion is the basis of its regulation of tip formation. Our study demonstrates that serotonin, recently appreciated for its developmental roles in widespread phyla6, also has a novel and ancient role in the formation and function of an organizer.

An Open Elite

2012 ◽  
Author(s):  
Walter W. Powell ◽  
Jason Owen-Smith
Keyword(s):  
Life Sciences ◽  
Creative Destruction ◽  
Core Group ◽  
Form And Function ◽  
Field Evolution ◽  
And Function

This chapter follows the trajectory of the life sciences into the present day, focusing on the larger question of industry or field evolution. In a field characterized by “gales of creative destruction,” the chapter considers how some types of organizations have managed to retain a position of centrality even as others exit and many newcomers arrive. It analyzes the emergence of a core group of organizations, diverse in form and function, which they label an “open elite.” The animating question is why this group of organizations, which constituted a structural backbone of the field, did not become ossified gatekeepers but remained active in expansive exploration. The answer is found in their multiconnectivity—the multiple, independent pathways that link research-focused organizations in a wide array of different activities.

An investigation into plasmolysis in the oomycete Achlya bisexualis reveals that membrane–wall attachment points are sensitive to peptides containing the sequence RGD and that cell wall deposition can occur despite retraction of the protoplast

2012 ◽  
Vol 58 (10) ◽  
pp. 1212-1220 ◽  
Author(s):  
Kenny Chitcholtan ◽  
Elisa Harris ◽  
YuPing Yu ◽  
Chad Harland ◽  
Ashley Garrill
Keyword(s):  
Cell Wall ◽  
Focal Adhesions ◽  
Structure And Function ◽  
Dependent Manner ◽  
Wall Deposition ◽  
Attachment Sites ◽  
And Function ◽  
Dose Dependent ◽  
Cell Wall Deposition ◽  
Achlya Bisexualis

The structure and function of membrane–wall attachment sites in walled cells, and how these relate to animal focal adhesions, is an area that is poorly understood. In view of this, we investigated how membrane–wall attachments that form upon plasmolysis, respond to peptides that disrupt animal focal adhesions. The degree of cytoplasmic disruption during plasmolysis was also investigated. Upon hyperosmotic challenge, the protoplast in hyphae of the oomycete Achlya bisexualis typically retracted incompletely due to membrane–wall attachments. The inclusion, in the plasmolysing solution, of peptides containing the sequence RGD disrupted these attachments in a dose-dependent manner. In some hyphae, protoplast retraction stopped temporarily at attachment points — upon resumption of retraction, material was left that traced the outline of the static protoplast. Staining of this material with fluorescence brightener indicated the presence of cellulose, which suggests that wall deposition was able to occur despite plasmolysis. The F-actin cytoskeleton was disrupted during plasmolysis; peripheral F-actin staining was observed, but there was no distinct F-actin cap; staining was more diffuse; and there were fewer plaques compared with nonplasmolysed hyphae. Our data indicate that membrane–wall attachment points are sensitive to RGD-containing peptides and that wall deposition continues despite protoplast retraction and F-actin disruption.

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