Search results for "Tunica"
showing 10 items of 128 documents
Sugar specific cellular lectins of Phallusia mamillata hemocytes: Purification, characterization and evidence for cell surface localization
1989
Cellular lectins (CLs) of Phallusia mamillata were demonstrated in protein preparations obtained by salt fractionation from hemocytes sonicated in a suitable medium. Since the lectins from the precipitated fraction bind sugars containing D-galactosyl groups, they were purified by affinity chromatography on Sepharose. SDS-PAGE under reducing conditions showed that CLs are formed of two components of apparent MWs approximately 36,900 and 35,090 and thus differ from serum lectins (SLs) (MW about 62,200). The "shrinkage" observed when SLs were examined under nonreducing conditions suggest the presence of intrachain disulphide bonds which can affect the molecular structure of the SLs. CL-SL diff…
In Vitro Release of Lectins From Phallusia mamillata Hemocytes After Their Fractionation on a Density Gradient
1993
Hemocytes were fractionated by centrifugation on a discontinuous Percoll density gradient from the hemolymph of Phallusia mamillata. Results obtained from microcultures of the fractionated hemocytes, sugar-inhibition experiments, SDS-PAGE, and immunoblotting indicate that “compartment cells” release cellular-type (CL) lectins that are specific for α-lactose and lactulose. The released lectins have the same properties as the CL lectins that were previously isolated from sonicated unfractionated hemocytes, but they differ in terms of some molecular and immunological properties from the lectins (SL) purified from the serum. SLs were never found in the supernatants from microcultures of the fra…
Assessment of Endoplasmic Reticulum Stress and the Unfolded Protein Response in Endothelial Cells
2011
In the vascular wall, the most inner cell layer that separates the blood from organelles is comprised of only a single layer of endothelial cells (ECs). This cell type is fundamental to a large variety of processes, ranging from blood coagulation and interaction with inflammatory cells to cardiovascular diseases such as hypertension, diabetes, and atherosclerosis. Dysfunction of ECs is often causally linked to these processes such that research exploring such events attracted much attention. Damage of ECs and subsequent disruption of the intact endothelial barrier can result not only from oxidative stress, but also from conditions that stress the endoplasmic reticulum (ER) and induce a sign…
Processing without proteolytic cleavage is required for recognition of insulin by T cells.
1990
Beef insulin as well as a chymotryptic A-chain fragment [BI-A1-14(SSO3-)3] need uptake by antigen-presenting cells (APC) for efficient presentation in combination with major histocompatibility complex class II molecules to insulin-specific T cells. This could be shown by the inability of aldehyde-fixed APC to present these antigens to T cells. Furthermore, presentation of the insulin fragment as well as presentation of ovalbumin (OVA) was inhibited by treatment of APC with chloroquine, cerulenin or tunicamycin. This was not the case for a processing-independent OVA peptide. Treatment of APC during antigen pulsing with various protease inhibitors, active on all classes of proteases, did not …
Cloning of Sponge (Geodia cydonium) and Tunicate (Botryllus schlosseri) Proteasome Subunit Epsilon (PRCE): Implications about the Vertebrate MHC-Enco…
1996
Proteasomes are large protein complexes that play a major role in selective degradation of intracellular proteins. Eukaryotes feature seven different alpha and beta subunits. Two of the vertebrate housekeeping beta-subunits have MHC-encoded homologues that can substitute for the housekeeping counterparts upon interferon-gamma induction. In the present study we report the cloning of invertebrate beta-subunit proteasome epsilon (PRCE), from the marine sponge Geodia cydonium and from the colonial tunicate Botryllus schlosseri. Sequence comparisons revealed that the sponge and tunicate proteins are strikingly similar to vertebrate and yeast PRCEs and their MHC-linked counterparts the PRCCs (als…
Processing requirements for the recognition of insulin fragments by murine T cells.
1988
In this study we investigated aspects of antigen processing using insulin and insulin A chain-derived fragments as model antigens in Ab alpha Ak beta-restricted T-cell stimulation. Similarly to other proteins, the immunodominant region of insulin recognized by these T cells is limited in size. It is located on the insulin A chain and encompasses a portion of the molecule that is represented faithfully by peptide A1-14(SSO3-)3. Efficient presentation of intact insulin and its entire A chain is dependent on uptake and processing by APC. Whereas peptides stemming from various globular proteins are known to be presented to T cells by APC without requiring processing, this is not the case with A…
A tunicate (Botryllus schlosseri) cDNA reveals similarity to vertebrate antigen receptors
1996
Biomechanical properties and histomorphometric features of aortic tissue in patients with or without bicuspid aortic valve
2020
Background We sought to investigate and compare biomechanical properties and histomorphometric findings of thoracic ascending aorta aneurysm (TAA) tissue from patients with bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) in order to clarify mechanisms underlying differences in the clinical course. Methods Circumferential sections of TAA tissue in patients with BAV (BAV-TAA) and TAV (TAV-TAA) were obtained during surgery and used for biomechanical tests and histomorphometrical analysis. Results In BAV-TAA, we observed biomechanical higher peak stress and lower Young modulus values compared with TAV-TAA wall. The right lateral longitudinal region seemed to be the most fragile zon…
Prophenoloxidase activating system in tunicate hemolymph
1996
The activation sequence and related factors of the prophenoloxidase activating system in crustaceans was compared with the equivalent system in tunicates. Both solitary and colonial ascidians present in their hemolymph a copper-dependent phenoloxidase activity that may be inhibited by tropolone and phenylthiourea. Carbohydrates are able, to various extents, to trigger proPO system which requires serine protease cleavage for activation to phenoloxidase (PO). In some ascidians, hemocytes called ≪morula cells≫ show PO activity, while in Ciona intestinalis the ≪univacuolar refractile granulocytes≫ are positive after cytochemical staining with L-dopa. The relationships between proPO system and d…