scholarly journals A novel putative microtubule-associated protein is involved in arbuscule development during arbuscular mycorrhiza formation

2021 ◽  
Author(s):  
Tania Ho-Plágaro ◽  
Raúl Huertas ◽  
María I Tamayo-Navarrete ◽  
Elison Blancaflor ◽  
Nuria Gavara ◽  
...  
Keyword(s):  
Plant Root ◽  
Arbuscular Mycorrhizal ◽  
Host Cells ◽  
Root Cells ◽  
Filament Dynamics ◽  
Fungal Structure ◽  
Genes Encoding ◽  
Associated Proteins ◽  
Mycorrhizal Development

Abstract The formation of arbuscular mycorrhizal (AM) symbiosis requires plant root host cells to undergo major structural and functional reprogramming in order to house the highly branched AM fungal structure for the reciprocal exchange of nutrients. These morphological modifications are associated with cytoskeleton remodelling. However, molecular bases and the role of microtubules (MTs) and actin filament dynamics during AM formation are largely unknown. In this study, the tomato tsb gene, belonging to a Solanaceae group of genes encoding MT-associated proteins for pollen development, was found to be highly expressed in root cells containing arbuscules. At earlier stages of mycorrhizal development, tsb overexpression enhanced the formation of highly developed and transcriptionally active arbuscules, while tsb silencing hampers the formation of mature arbuscules and represses arbuscule functionality. However, at later stages of mycorrhizal colonization, tsb OE roots accumulate fully developed transcriptionally inactive arbuscules, suggesting that the collapse and turnover of arbuscules might be impaired by TSB accumulation. Imaging analysis of the MT cytoskeleton in cortex root cells overexpressing tsb revealed that TSB is involved in MT-bundling. Taken together, our results provide unprecedented insights into the role of novel MT-associated protein in MT rearrangements throughout the different stages of the arbuscule life cycle.

scholarly journals Schistosome tegumental ecto-apyrase (SmATPDase1) degrades exogenous pro-inflammatory and pro-thrombotic nucleotides.

2014 ◽  
Author(s):  
Akram A Da'dara ◽  
Rita Bhardwaj ◽  
Yasser MB Ali ◽  
Patrick Skelly
Keyword(s):  
Thrombus Formation ◽  
Functional Characterization ◽  
Host Cells ◽  
Dependent Manner ◽  
Host Immune Responses ◽  
Genes Encoding ◽  
Molecular Patterns ◽  
Parasitic Worms ◽  
Damage Associated Molecular Patterns

Schistosomes are parasitic worms that can survive in the hostile environment of the human bloodstream where they appear refractory to both immune elimination and thrombus formation. We hypothesize that parasite migration in the bloodstream can stress the vascular endothelium causing this tissue to release chemicals alerting responsive host cells to the stress. Such chemicals are called damage associated molecular patterns (DAMPs) and among the most potent is the proinflammatory mediator, adenosine triphosphate (ATP). Furthermore, the ATP derivative ADP is a pro-thrombotic molecule that acts as a strong activator of platelets. Schistosomes are reported to possess at their host interactive tegumental surface a series of enzymes that could, like their homologs in mammals, degrade extracellular ATP and ADP. These are alkaline phosphatase (SmAP), phosphodiesterase (SmNPP-5) and ATP diphosphohydrolase (SmATPDase1). In this work we employ RNAi to knock down expression of the genes encoding these enzymes in the intravascular life stages of the parasite. We then compare the abilities of these parasites to degrade exogenously added ATP and ADP. . We find that only SmATPDase1-suppressed parasites are significantly impaired in their ability to degrade these nucleotides. Suppression of SmAP or SmNPP-5 does not appreciably affect the worms’ ability to catabolize ATP or ADP. These findings are confirmed by the functional characterization of the enzymatically active, full-length recombinant SmATPDase1 expressed in CHO-S cells. The enzyme is a true apyrase; SmATPDase1 degrades ATP and ADP in a cation dependent manner. Optimal activity is seen at alkaline pH. The Km of SmATPDase1 for ATP is 0.4 ±0.02 mM and for ADP, 0.252 ± 0.02 mM. The results confirm the role of tegumental SmATPDase1 in the degradation of the exogenous pro-inflammatory and pro-thrombotic nucleotides ATP and ADP by live intravascular stages of the parasite. By degrading host inflammatory signals like ATP, and pro-thrombotic signals like ADP, these parasite enzymes may minimize host immune responses, inhibit blood coagulation and promote schistosome survival.)

Hypertrophic cardiomyopathy: genetics

ESC CardioMed ◽  
2018 ◽  
pp. 1443-1450
Author(s):  
Mohammed Majid Akhtar ◽  
Luis Rocha Lopes
Keyword(s):  
Genetic Testing ◽  
Hypertrophic Cardiomyopathy ◽  
Mapk Pathway ◽  
Glycogen Storage ◽  
Cellular Level ◽  
Causative Mutation ◽  
Clinical Role ◽  
Genes Encoding ◽  
Associated Proteins

Hypertrophic cardiomyopathy is most commonly transmitted as an autosomal dominant trait, caused by mutations in genes encoding cardiac sarcomere and associated proteins. Knowledge of the genetic pathophysiology of the disease has advanced significantly since the initial identification of a point mutation in the beta-myosin heavy chain (MYH7) gene in 1990. Other genetic causes of the disease include mutations in genes coding for proteins implicated in calcium handling or which form part of the cytoskeleton. The recent emergence of next-generation sequencing allows quicker and less expensive identification of causative mutations. However, a causative mutation is not identified in up to 50% of probands. At present, the primary clinical role of genetic testing in hypertrophic cardiomyopathy is in the context of familial screening, allowing the identification of those at risk of developing the condition. Genetic testing can also be used to exclude genocopies, particularly in the presence of certain diagnostic ‘red flag’ features, where lysosomal, glycogen storage, neuromuscular or Ras-MAPK pathway disorders may be suspected. The role of individual mutations in predicting prognosis is limited at present. However, the higher incidence of sudden cardiac death in the presence of a family history of such, suggests that genetics play a significant role in determining outcome. With an increased understanding of the impact of these mutations on a cellular level and on longer-term clinical outcomes, the aim in future for gene and mutation specific prognosis or potential disease-modifying therapy is closer.

Hypertrophic cardiomyopathy: genetics

ESC CardioMed ◽  
2018 ◽  
pp. 1443-1450
Author(s):  
Mohammed Majid Akhtar ◽  
Luis Rocha Lopes
Keyword(s):  
Genetic Testing ◽  
Hypertrophic Cardiomyopathy ◽  
Mapk Pathway ◽  
Glycogen Storage ◽  
Cellular Level ◽  
Causative Mutation ◽  
Clinical Role ◽  
Genes Encoding ◽  
Associated Proteins

Hypertrophic cardiomyopathy is most commonly transmitted as an autosomal dominant trait, caused by mutations in genes encoding cardiac sarcomere and associated proteins. Knowledge of the genetic pathophysiology of the disease has advanced significantly since the initial identification of a point mutation in the beta-myosin heavy chain (MYH7) gene in 1990. Other genetic causes of the disease include mutations in genes coding for proteins implicated in calcium handling or which form part of the cytoskeleton. The recent emergence of next-generation sequencing allows quicker and less expensive identification of causative mutations. However, a causative mutation is not identified in up to 50% of probands. At present, the primary clinical role of genetic testing in hypertrophic cardiomyopathy is in the context of familial screening, allowing the identification of those at risk of developing the condition. Genetic testing can also be used to exclude genocopies, particularly in the presence of certain diagnostic ‘red flag’ features, where lysosomal, glycogen storage, neuromuscular or Ras-MAPK pathway disorders may be suspected. The role of individual mutations in predicting prognosis is limited at present. However, the higher incidence of sudden cardiac death in the presence of a family history of such, suggests that genetics play a significant role in determining outcome. With an increased understanding of the impact of these mutations on a cellular level and on longer-term clinical outcomes, the aim in future for gene and mutation specific prognosis or potential disease-modifying therapy is closer.

scholarly journals Enteropathogenic Escherichia coli (EPEC) Tir Receptor Molecule Does Not Undergo Full Modification When Introduced into Host Cells by EPEC-Independent Mechanisms

2001 ◽  
Vol 69 (3) ◽  
pp. 1444-1453 ◽  
Author(s):  
Brendan Kenny ◽  
Jonathan Warawa
Keyword(s):  
Escherichia Coli ◽  
Molecular Mass ◽  
Type Iii Secretion ◽  
Efficiency Factor ◽  
Host Cells ◽  
Sufficient Information ◽  
Phosphorylation Event ◽  
Associated Proteins ◽  
Phosphate Groups

ABSTRACT Enteropathogenic Escherichia coli (EPEC), like many other gram-negative pathogens, encodes a type III secretion apparatus dedicated to the release of virulence-associated proteins. One such protein, Tir, is translocated into host cells, where it is modified by the addition of phosphate groups, resulting in a number of species with distinct molecular mass. One phosphorylation event, on tyrosine residue 474 of Tir, does not contribute to shifts in molecular mass but is essential for its actin-nucleating function. The role of the nonphosphotyrosine related modifications is unknown. In this paper, we demonstrate, using three different approaches, that Tir does not encode sufficient information to facilitate its complete modification when introduced into host cells in EPEC-independent mechanisms. Each system revealed that Tir is a substrate for a host kinase whose action results in its partial modification to a form similar to one evident in EPEC-infected host cells. Further Tir modification could not be induced by infecting cells with EPEC, suggesting that Tir must be coexpressed with other EPEC factors to enable its full modification within host cells. One approach usedYersinia spp. to deliver Tir into host cells, and this system revealed that Tir secretion and translocation can occur in the absence of the Tir chaperone molecule, CesT (formerly known as OrfU). CesT was found to be an efficiency factor which was not required, unlike in EPEC, for Tir stability, indicating that it may function to guide Tir to the translocation apparatus or maintain it in a secretion-competent form.

scholarly journals Role of Endoplasmic Reticulum-Associated Proteins in Flavivirus Replication and Assembly Complexes

Pathogens ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 148 ◽  
Author(s):  
Hussin A. Rothan ◽  
Mukesh Kumar
Keyword(s):  
Endoplasmic Reticulum ◽  
Viral Proteins ◽  
Host Cells ◽  
Host Proteins ◽  
Multiprotein Complexes ◽  
Genome Wide ◽  
Associated Proteins ◽  
Cytoplasmic Side ◽  
Er Membrane

Flavivirus replication in host cells requires the formation of replication and assembly complexes on the cytoplasmic side of the endoplasmic reticulum (ER) membrane. These complexes consist of an ER membrane, viral proteins, and host proteins. Genome-wide investigations have identified a number of ER multiprotein complexes as vital factors for flavivirus replication. The detailed mechanisms of the role of ER complexes in flavivirus replication are still largely elusive. This review highlights the fact that the ER multiprotein complexes are crucial for the formation of flavivirus replication and assembly complexes, and the ER complexes could be considered as a target for developing successful broad-spectrum anti-flavivirus drugs.

scholarly journals Role of the Septin Ring in the Asymmetric Localization of Proteins at the Mother-Bud Neck in Saccharomyces cerevisiae

2005 ◽  
Vol 16 (8) ◽  
pp. 3455-3466 ◽  
Author(s):  
Lukasz Kozubowski ◽  
Jennifer R. Larson ◽  
Kelly Tatchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Septin Ring ◽  
Gtpase Activating Proteins ◽  
Latrunculin A ◽  
Bud Neck ◽  
Genes Encoding ◽  
Associated Proteins

In the yeast Saccharomyces cerevisiae, septins form a scaffold in the shape of a ring at the future budding site that rearranges into a collar at the mother-bud neck. Many proteins bind asymmetrically to the septin collar. We found that the protein Bni4-CFP was located on the exterior of the septin ring before budding and on the mother side of the collar after budding, whereas the protein kinase Kcc4-YFP was located on the interior of the septin ring before budding and moved into the bud during the formation of the septin collar. Unbudded cells treated with the actin inhibitor latrunculin-A assembled cortical caps of septins on which Bni4-CFP and Kcc4-YFP colocalized. Bni4-CFP and Kcc4-YFP also colocalized on cortical caps of septins found in strains deleted for the genes encoding the GTPase activating proteins of Cdc42 (RGA1, RGA2, and BEM3). However, Bni4-CFP and Kcc4-YFP were still partially separated in mutants (gin4, elm1, cla4, and cdc3-1) in which septin morphology was severely disrupted in other ways. These observations provide clues to the mechanisms for the asymmetric localization of septin-associated proteins.

The rôle of aluminium in soil infertility and toxicity

1926 ◽  
Vol 16 (4) ◽  
pp. 616-631 ◽  
Author(s):  
F. Hardy
Keyword(s):  
Plant Species ◽  
Agricultural Soils ◽  
Culture Media ◽  
Plant Root ◽  
Plant Distribution ◽  
Soluble Form ◽  
Colloidal Systems ◽  
Nutrient Media ◽  
Root Cells

1. The main results of soil investigations on the rôle of aluminium in soil infertility are reviewed, with particular regard to the physicochemical principles involved.2. Magistad's conclusion that soils or other nutrient media whose reaction values lie within the range pH 4·7 and pH 8·5 do not contain aluminium in soluble form, and are probably therefore not toxic to plants, is discussed in the light of modern knowledge of the properties of hydrous alumina and its peptisation phenomena.3. Dialysis experiments which have led to this generalisation are criticised on the grounds that they do not take into account the disturbing effect of dialysis on hydrous colloidal systems, and that dialyser membranes do not simulate plant-cell membranes.4. Aluminium may possibly penetrate plant-root cells, and, under certain conditions, may be translocated, within the plant body, in at least four different forms, namely, (a) simple ions, (b) more complex colloidal electrolytes, (c) co-ordinated complex anions, and (d) organo-compounds. These may conceivably be interconvertible.5. Aluminium appears to exert true toxic effect only when presented to plant roots as simple ions, or as the more soluble colloidal electrolytes. Apparently, the degree of toxicity varies for different plant species.6. The reaction conditions of nutrient media and of plant saps doubtless largely decide the form in which aluminium occurs therein. At reactions approaching the isoelectric point of hydrous alumina, toxic effects may never be exerted, although the assignation of a strict reaction-range applicable to all soils or nutrient media, and to all plant species, is probably inadmissible.7. Non-toxic forms of aluminium may apparently accumulate under certain conditions at definite tissue regions of certain plants, and may disturb their metabolic processes, disposing the plants to certain diseases.8. Within the reaction-range at which toxic aluminous solutes cannot exist in soils or other culture media, hydrogen-ions may exert controlling influence on plant growth, and may thus be of major significance in natural plant distribution, and in the behaviour of plants growing in normal agricultural soils.

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