scholarly journals The Essential Role of Tick Salivary Glands and Saliva in Tick Feeding and Pathogen Transmission

2017 ◽  
Vol 7 ◽  
Author(s):  
Ladislav Šimo ◽  
Maria Kazimirova ◽  
Jennifer Richardson ◽  
Sarah I. Bonnet
Keyword(s):  
Salivary Glands ◽  
Essential Role ◽  
Pathogen Transmission ◽  
Tick Feeding ◽  
Tick Salivary Glands

scholarly journals Spotted Fever GroupRickettsiaInfection and Transmission Dynamics inAmblyomma maculatum

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Chanakan Suwanbongkot ◽  
Ingeborg M. Langohr ◽  
Emma K. Harris ◽  
Wellesley Dittmar ◽  
Rebecca C. Christofferson ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Spotted Fever ◽  
Attachment Site ◽  
Spotted Fever Group ◽  
Tick Feeding ◽  
Tick Saliva ◽  
Content Type ◽  
Feeding Site ◽  
Vertebrate Hosts ◽  
Tick Salivary Glands

ABSTRACTTick vectors are capable of transmitting several rickettsial species to vertebrate hosts, resulting in various levels of disease. Studies have demonstrated the transmissibility of both rickettsial pathogens and novelRickettsiaspecies or strains with unknown pathogenicity to vertebrate hosts during tick blood meal acquisition; however, the quantitative nature of transmission remains unknown. We tested the hypothesis that if infection severity is a function of the rickettsial load delivered during tick transmission, then a more virulent spotted fever group (SFG)Rickettsiaspecies is transmitted at higher levels during tick feeding. UsingAmblyomma maculatumcohorts infected withRickettsia parkerior “CandidatusRickettsia andeanae,” a quantitative PCR (qPCR) assay was employed to quantify rickettsiae in tick salivary glands and saliva, as well as in the vertebrate hosts at the tick attachment site over the duration of tick feeding. Significantly greater numbers ofR. parkerithan of “Ca. Rickettsia andeanae” rickettsiae were present in tick saliva and salivary glands and in the vertebrate hosts at the feeding site during tick feeding. Microscopy demonstrated the presence of both rickettsial species in tick salivary glands, and immunohistochemical analysis of the attachment site identified localizedR. parkeri, but not “Ca. Rickettsia andeanae,” in the vertebrate host. Lesions were also distinct and more severe in vertebrate hosts exposed toR. parkerithan in those exposed to “Ca. Rickettsia andeanae.” The specific factors that contribute to the generation of a sustained rickettsial infection and subsequent disease have yet to be elucidated, but the results of this study suggest that the rickettsial load in ticks and during transmission may be an important element.

scholarly journals Insights into the Role of Tick Salivary Protease Inhibitors during Ectoparasite–Host Crosstalk

2021 ◽  
Vol 22 (2) ◽  
pp. 892
Author(s):  
Mohamed Amine Jmel ◽  
Hajer Aounallah ◽  
Chaima Bensaoud ◽  
Imen Mekki ◽  
Jindřich Chmelař ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Protease Inhibitors ◽  
High Specificity ◽  
Practical Applications ◽  
Drug Candidates ◽  
And Function ◽  
Anti Fungal ◽  
Tick Salivary Glands

Protease inhibitors (PIs) are ubiquitous regulatory proteins present in all kingdoms. They play crucial tasks in controlling biological processes directed by proteases which, if not tightly regulated, can damage the host organism. PIs can be classified according to their targeted proteases or their mechanism of action. The functions of many PIs have now been characterized and are showing clinical relevance for the treatment of human diseases such as arthritis, hepatitis, cancer, AIDS, and cardiovascular diseases, amongst others. Other PIs have potential use in agriculture as insecticides, anti-fungal, and antibacterial agents. PIs from tick salivary glands are special due to their pharmacological properties and their high specificity, selectivity, and affinity to their target proteases at the tick–host interface. In this review, we discuss the structure and function of PIs in general and those PI superfamilies abundant in tick salivary glands to illustrate their possible practical applications. In doing so, we describe tick salivary PIs that are showing promise as drug candidates, highlighting the most promising ones tested in vivo and which are now progressing to preclinical and clinical trials.

Essential role of Sharpin in TNFα dependent NFκB activation in primary hepatocytes

2012 ◽  
Vol 50 (01) ◽  
Author(s):  
N Lange ◽  
S Sieber ◽  
A Erhardt ◽  
G Sass ◽  
HJ Kreienkamp ◽  
...  
Keyword(s):  
Essential Role ◽  
Primary Hepatocytes

Different Abilities of Thrombin Receptor Activating Peptide and Thrombin to Induce Platelet Calcium Rise and Full Release Reaction

1995 ◽  
Vol 74 (05) ◽  
pp. 1323-1328 ◽  
Author(s):  
Dominique Lasne ◽  
José Donato ◽  
Hervé Falet ◽  
Francine Rendu
Keyword(s):  
Essential Role ◽  
Calcium Influx ◽  
Dense Granule ◽  
Receptor Interaction ◽  
Thrombin Receptor ◽  
Release Reaction ◽  
External Calcium ◽  
Maximum Rise ◽  
Granule Release

SummarySynthetic peptides (TRAP or Thrombin Receptor Activating Peptide) corresponding to at least the first five aminoacids of the new N-terminal tail generated after thrombin proteolysis of its receptor are effective to mimic thrombin. We have studied two different TRAPs (SFLLR, and SFLLRN) in their effectiveness to induce the different platelet responses in comparison with thrombin. Using Indo-1/AM- labelled platelets, the maximum rise in cytoplasmic ionized calcium was lower with TRAPs than with thrombin. At threshold concentrations allowing maximal aggregation (50 μM SFLLR, 5 μM SFLLRN and 1 nM thrombin) the TRAPs-induced release reaction was about the same level as with thrombin, except when external calcium was removed by addition of 1 mM EDTA. In these conditions, the dense granule release induced by TRAPs was reduced by over 60%, that of lysosome release by 75%, compared to only 15% of reduction in the presence of thrombin. Thus calcium influx was more important for TRAPs-induced release than for thrombin-induced release. At strong concentrations giving maximal aggregation and release in the absence of secondary mediators (by pretreatment with ADP scavengers plus aspirin), SFLLRN mobilized less calcium, with a fast return towards the basal level and induced smaller lysosome release than did thrombin. The results further demonstrate the essential role of external calcium in triggering sustained and full platelet responses, and emphasize the major difference between TRAP and thrombin in mobilizing [Ca2+]j. Thus, apart from the proteolysis of the seven transmembrane receptor, another thrombin binding site or thrombin receptor interaction is required to obtain full and complete responses.

Collagen-Induced Platelet Aggregation: -Evidence Against the Essential Role of Platelet Adenosine Diphosphate

1979 ◽  
Vol 42 (04) ◽  
pp. 1193-1206 ◽  
Author(s):  
Barbara Nunn
Keyword(s):  
Platelet Aggregation ◽  
Time Course ◽  
Essential Role ◽  
Atp Release ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
High Doses ◽  
Induced Aggregation

SummaryThe hypothesis that platelet ADP is responsible for collagen-induced aggregation has been re-examined. It was found that the concentration of ADP obtaining in human PRP at the onset of aggregation was not sufficient to account for that aggregation. Furthermore, the time-course of collagen-induced release in human PRP was the same as that in sheep PRP where ADP does not cause release. These findings are not consistent with claims that ADP alone perpetuates a collagen-initiated release-aggregation-release sequence. The effects of high doses of collagen, which released 4-5 μM ADP, were not inhibited by 500 pM adenosine, a concentration that greatly reduced the effect of 300 μM ADP. Collagen caused aggregation in ADP-refractory PRP and in platelet suspensions unresponsive to 1 mM ADP. Thus human platelets can aggregate in response to collagen under circumstances in which they cannot respond to ADP. Apyrase inhibited aggregation and ATP release in platelet suspensions but not in human PRP. Evidence is presented that the means currently used to examine the role of ADP in aggregation require investigation.

Le premier moment de l’art dans À la recherche du temps perdu de Marcel Proust – une « leçon d’idéalisme » ?

2020 ◽  
pp. 25-40
Author(s):  
Larisa Botnari
Keyword(s):  
Essential Role ◽  
Marcel Proust ◽  
The Self ◽  
Philosophy Of Art ◽  
The Novel ◽  
Philosophical Interpretation ◽  
German Philosopher ◽  
Lost Time ◽  
Aesthetic Thinking

Although very famous, some key moments of the novel In Search of Lost Time, such as those of the madeleine or the uneven pavement, often remain enigmatic for the reader. Our article attempts to formulate a possible philosophical interpretation of the narrator's experiences during these scenes, through a confrontation of the Proustian text with the ideas found in the System of Transcendental Idealism (1800) of the German philosopher F. W. J. Schelling. We thus try to highlight the essential role of the self in Marcel Proust's aesthetic thinking, by showing that the mysterious happiness felt by the narrator, and from which the project of creating a work of art is ultimately born, is similar to the experiences of pure self-consciousness evoked and analyzed by Schellingian philosophy of art.

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