The structure and function of the adhesive organ in strigeid trematodes

Parasitology ◽  
1966 ◽  
Vol 56 (3) ◽  
pp. 481-491 ◽  
Author(s):  
Christina Öhman
Keyword(s):  
Leucine Aminopeptidase ◽  
Gland Cells ◽  
Adhesive Organ ◽  
Diplostomum Spathaceum ◽  
Secretory Products ◽  
And Function ◽  
The University ◽  
Cyathocotyle Bushiensis

The biology and life-cycle of Holostephanus lühei is briefly described. The similarities in morphology between the adhesive organ gland cells of H. lühei and Cyathocotyle bushiensis are stressed. Alkaline and acid phosphatases were demonstrated in the adhesive organ gland cells and cuticle. Acid phosphatase also occurs in the caecal cells. Non-specific esterase, sensitive to E600 10−5M and Mipafox 10−3M, is present in the gland cells. The caeca contain a non-specific esterase sensitive to AgNO3 10−2M and PCMB 10−4M. Leucine aminopeptidase is present in the gland cells. The in vitro studies confirmed that the secretory products pass to the exterior of the parasite and have a histolytic action.The four strigeids studied, Cyathocotyle bushiensis, Holostephanus lühei, Diplostomum spathaceum and Apatemon gracilis minor, are compared and the biological role of the secreted enzymes are discussed.My sincere thanks are due to Dr D. A. Erasmus for suggesting this line of investigation and for his encouragement during the study. I am also grateful for his performing, on my behalf, the infection experiments and criticizing the manuscript. I wish to thank Professor J. Brough for his interest in the progress of the work, and the University College, Cardiff, for a grant from William E. Morgan's Bequest.

The structure and function of the adhesive organ in strigeid trematodes

Parasitology ◽  
1965 ◽  
Vol 55 (3) ◽  
pp. 481-502 ◽  
Author(s):  
Christina Öhman
Keyword(s):  
Alkaline Phosphatase ◽  
Acid Phosphatase ◽  
Aminopeptidase Activity ◽  
Short Account ◽  
Gland Cells ◽  
Adhesive Organ ◽  
Diplostomum Spathaceum ◽  
And Function ◽  
Host Tissues

A short account of the biology and life-cycle of Diplostomum spathaceum is given.The morphology of the forebody is described in some detail. The lappets are well developed and function as organs of attachment as well as being reservoirs for the secretion from the forebody gland cells. The adhesive organ is variable in form and the muscles facilitating the movements are described in detail. Pressure changes in the excretory system are thought to assist in evaginating the adhesive organ.The histochemical tests gave the following results. The phosphatases present in the adhesive organ and the forebody gland cells are of the acid variety, the alkaline phosphatase is only present in the cuticle, traces of it occur in the lappets and forebody gland cells. No leucine aminopeptidase activity was observed. The esterase present is either a pseudocholinesterase or a non-specific B-esterase. The presence of RNA is confined to areas of enzyme formation.The in vitro studies confirmed the absence of alkaline phosphatase and the presence of acid phosphatase and esterase in the forebody. They also showed a secretion of acid phosphatase and esterase to the exterior of the parasite.Diplostomum spathaceum has very little effect on the host mucosa, but some lysis of the host tissues in contact with the forebody and especially the lappets, is observed. The response of the host to the parasite is likewise very small.The source of nutrients for D. spathaceum is believed to be the contents of the host alimentary tract, host mucus secretions and to a small extent disintegrated host tissues.I am very grateful to Dr D. A. Erasmus for advice and encouragement during this study and to Professor J. Brough for his interest and for provision of excellent working facilities. The work was conducted during the tenure of a Rotary Foundation Scholarship for International Understanding and a grant from Nylands Nation (Helsingfors, Finland).

Investigating the role of arginine 21 in the structure and function of human [alpha]a-crystallin

2018 ◽  
Author(s):  
◽  
Ashutosh Shripad Phadte
Keyword(s):  
Functional Characterization ◽  
Lens Fiber Cell ◽  
University Of Missouri ◽  
Mutant Proteins ◽  
Plausible Mechanism ◽  
And Function ◽  
The University

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Cataractogenesis in the eye lens occurs as a result of protein aggregation. Of the multiple mutations in [alpha]A-crystallins associated with the development of congenital hereditary cataract, three identified mutations target R21 within the N- terminal domain of the protein. On structural and functional characterization of a recently identified mutant of [alpha]A-crystallin, [alpha]A-R21Q, we revealed the contribution of R21 in dictating the interaction of [alpha]A-crystallin with other proteins. [alpha]A-R21Q showed and enhanced chaperone-like function, and increased binding to lens fiber cell membranes. Transduction of mutant proteins in ARPE-19 cells prevented their apoptosis in the presence of oxidative stress, suggesting a role for R21 in modulating the anti-apoptotic function of [alpha]A-crystallin. In addition, the R21Q point mutation rescued the chaperone-like activity of [alpha]A-G98R crystallin as well as palliated [alpha]A-G98R mediated cytotoxicity otherwise observed in transduction experiments. Although another mutation, R157Q rescued the chaperone-like activity of [alpha]A-G98R, the double mutant exhibited a loss of its cytoprotective function. The results therefore implicate an important role of R21 in regulating the functional aspect of [alpha]A-crystallin. [alpha]A-crystallin derived peptides have been shown to prevent non-specific aggregation of unfolding proteins in vitro. We show that the [alpha]A-crystallin derived mini-chaperone (mini-[alpha]A) mediated stabilization of self-aggregating [alpha]A-G98R crystallin and bovine [subscript]-crystallin occurs via compensation of lost surface charge. The observation therefore suggests a plausible mechanism of action of [alpha]A-crystallin derived peptides of therapeutic interest.

Investigating the role of arginine 21 in the structure and function of human [alpha]A-crystallin

2018 ◽  
Author(s):  
◽  
Ashutosh S. Phadte
Keyword(s):  
Functional Characterization ◽  
Lens Fiber Cell ◽  
University Of Missouri ◽  
Mutant Proteins ◽  
Plausible Mechanism ◽  
And Function ◽  
The University

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Cataractogenesis in the eye lens occurs as a result of protein aggregation. Of the multiple mutations in [alpha]A-crystallins associated with the development of congenital hereditary cataract, three identified mutations target R21 within the N-terminal domain of the protein. On structural and functional characterization of a recently identified mutant of [alpha]A-crystallin, [alpha]A-R21Q, we revealed the contribution of R21 in dictating the interaction of [alpha]A-crystallin with other proteins. [Alpha]A-R21Q showed and enhanced chaperone-like function, and increased binding to lens fiber cell membranes. Transduction of mutant proteins in ARPE-19 cells prevented their apoptosis in the presence of oxidative stress, suggesting a role for R21 in modulating the anti-apoptotic function of [alpha]A-crystallin. In addition, the R21Q point mutation rescued the chaperone-like activity of [alpha]A-G98R crystallin as well as palliated [alpha]A-G98R mediated cytotoxicity otherwise observed in transduction experiments. Although another mutation, R157Q rescued the chaperone-like activity of [alpha]A-G98R, the double mutant exhibited a loss of its cytoprotective function. The results therefore implicate an important role of R21 in regulating the functional aspect of [alpha]A-crystallin. [Alpha]A-crystallin derived peptides have been shown to prevent non-specific aggregation of unfolding proteins in vitro. We show that the [alpha]A-crystallin derived mini-chaperone (mini-[alpha]A) mediated stabilization of self-aggregating [alpha]A-G98R crystallin and bovine [gamma]-crystallin occurs via compensation of lost surface charge. The observation therefore suggests a plausible mechanism of action of [alpha]A-crystallin derived peptides of therapeutic interest.

Role of the 807 C/T Polymorphism of the α2 Gene in Platelet GP Ia Collagen Receptor Expression and Function

1999 ◽  
Vol 81 (06) ◽  
pp. 951-956 ◽  
Author(s):  
J. Corral ◽  
R. González-Conejero ◽  
J. Rivera ◽  
F. Ortuño ◽  
P. Aparicio ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Cell Types ◽  
Receptor Expression ◽  
Case Control Studies ◽  
Platelet Surface ◽  
Vitro Analysis ◽  
And Function ◽  
In Vitro Analysis

SummaryThe variability of the platelet GP Ia/IIa density has been associated with the 807 C/T polymorphism (Phe 224) of the GP Ia gene in American Caucasian population. We have investigated the genotype and allelic frequencies of this polymorphism in Spanish Caucasians. The T allele was found in 35% of the 284 blood donors analyzed. We confirmed in 159 healthy subjects a significant association between the 807 C/T polymorphism and the platelet GP Ia density. The T allele correlated with high number of GP Ia molecules on platelet surface. In addition, we observed a similar association of this polymorphism with the expression of this protein in other blood cell types. The platelet responsiveness to collagen was determined by “in vitro” analysis of the platelet activation and aggregation response. We found no significant differences in these functional platelet parameters according to the 807 C/T genotype. Finally, results from 3 case/control studies involving 302 consecutive patients (101 with coronary heart disease, 104 with cerebrovascular disease and 97 with deep venous thrombosis) determined that the 807 C/T polymorphism of the GP Ia gene does not represent a risk factor for arterial or venous thrombosis.

scholarly journals Membrane-associated phase separation: organization and function emerge from a two-dimensional milieu

2021 ◽  
Author(s):  
Jonathon A Ditlev
Keyword(s):  
Phase Separation ◽  
Cell Biology ◽  
Cellular Environment ◽  
Condensate Formation ◽  
Associated Proteins ◽  
Available Technology ◽  
And Function ◽  
Surrounding Membrane

Abstract Liquid‒liquid phase separation (LLPS) of biomolecules has emerged as an important mechanism that contributes to cellular organization. Phase separated biomolecular condensates, or membrane-less organelles, are compartments composed of specific biomolecules without a surrounding membrane in the nucleus and cytoplasm. LLPS also occurs at membranes, where both lipids and membrane-associated proteins can de-mix to form phase separated compartments. Investigation of these membrane-associated condensates using in vitro biochemical reconstitution and cell biology has provided key insights into the role of phase separation in membrane domain formation and function. However, these studies have generally been limited by available technology to study LLPS on model membranes and the complex cellular environment that regulates condensate formation, composition, and function. Here, I briefly review our current understanding of membrane-associated condensates, establish why LLPS can be advantageous for certain membrane-associated condensates, and offer a perspective for how these condensates may be studied in the future.

Abstract 445: A Pro-Fibrotic Role of Interleukin-4 in Cardiac Remodeling and Dysfunction

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Hongmei Peng ◽  
Oscar Carretero ◽  
Xiao-Ping Yang ◽  
Pablo Nakagawa ◽  
Jiang Xu ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Cardiac Fibroblasts ◽  
Interleukin 4 ◽  
Ang Ii ◽  
Collagen Production ◽  
And Function ◽  
First Time ◽  
Mini Pump

Elevated interleukin-4 (IL-4) levels are positively related to cardiac fibrosis in heart failure and hypertension. Using Balb/c exhibiting high circulating IL-4, Balb/c- Il4 tm2Nnt (IL-4 knockout with Balb/c background, IL-4 -/- ) and C57BL/6 mice, as well as cultured cardiac fibroblasts (CFs), we hypothesized that 1) high levels of IL-4 result in cardiac fibrosis, making the heart susceptible to angiotensin II (Ang II)-induced damage, and 2) IL-4 potently stimulates collagen production by CFs. Each strain (9- to 12-week old male) received vehicle or Ang II (1.4 mg/kg/day, s.c. via osmotic mini-pump) for 8 weeks. Cardiac fibrosis and function were determined by histology and echocardiography, respectively. Compared to C57BL/6, Balb/c mice had doubled interstitial collagen in the heart, enlarged left ventricle and decreased cardiac function along with elevated cardiac IL-4 protein (1.00±0.08 in C57BL/6 vs 2.61±0.46 in Balb/c, p <0.05); all those changes were significantly attenuated in IL-4 -/- (Table 1). Ang II further deteriorated cardiac fibrosis and dysfunction in Balb/c; these detrimental effects were attenuated in IL-4 -/- , although the three strains had a similar level of hypertension. In vitro study revealed that IL-4Rα was constitutively expressed in CFs (Western blot), and IL-4 potently stimulated collagen production by CFs (hydroxproline assay, from 18.89±0.85 to 38.81±3.61 μg/mg at 10 ng/ml, p <0.01). Our study demonstrates for the first time that IL-4, as a potent pro-fibrotic cytokine in the heart, contributes to cardiac fibrotic remodeling and dysfunction. Thus IL-4 may be a potential therapeutic target for cardiac fibrosis and dysfunction.

scholarly journals Inhibition of O-GlcNAc Transferase Alters the Differentiation and Maturation Process of Human Monocyte Derived Dendritic Cells

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3312
Author(s):  
Matjaž Weiss ◽  
Marko Anderluh ◽  
Martina Gobec
Keyword(s):  
Dendritic Cells ◽  
Posttranslational Modification ◽  
Human Monocyte ◽  
T Cell Differentiation ◽  
Maturation Process ◽  
Hla Dr ◽  
Glcnac Transferase ◽  
And Function

The O-GlcNAcylation is a posttranslational modification of proteins regulated by O-GlcNAc transferase (OGT) and O-GlcNAcase. These enzymes regulate the development, proliferation and function of cells, including the immune cells. Herein, we focused on the role of O-GlcNAcylation in human monocyte derived dendritic cells (moDCs). Our study suggests that inhibition of OGT modulates AKT and MEK/ERK pathways in moDCs. Changes were also observed in the expression levels of relevant surface markers, where reduced expression of CD80 and DC-SIGN, and increased expression of CD14, CD86 and HLA-DR occurred. We also noticed decreased IL-10 and increased IL-6 production, along with diminished endocytotic capacity of the cells, indicating that inhibition of O-GlcNAcylation hampers the transition of monocytes into immature DCs. Furthermore, the inhibition of OGT altered the maturation process of immature moDCs, since a CD14medDC-SIGNlowHLA-DRmedCD80lowCD86high profile was noticed when OGT inhibitor, OSMI-1, was present. To evaluate DCs ability to influence T cell differentiation and polarization, we co-cultured these cells. Surprisingly, the observed phenotypic changes of mature moDCs generated in the presence of OSMI-1 led to an increased proliferation of allogeneic T cells, while their polarization was not affected. Taken together, we confirm that shifting the O-GlcNAcylation status due to OGT inhibition alters the differentiation and function of moDCs in in vitro conditions.

scholarly journals Functional Role of N-Linked Glycosylation in Pseudorabies Virus Glycoprotein gH

2018 ◽  
Vol 92 (9) ◽  
pp. e00084-18 ◽  
Author(s):  
Melina Vallbracht ◽  
Sascha Rehwaldt ◽  
Barbara G. Klupp ◽  
Thomas C. Mettenleiter ◽  
Walter Fuchs
Keyword(s):  
Pseudorabies Virus ◽  
Viral Envelope ◽  
Fusion Activity ◽  
Virus Particles ◽  
Glycosylation Sites ◽  
Functional Relevance ◽  
And Function ◽  
Cell Spread

ABSTRACTMany viral envelope proteins are modified by asparagine (N)-linked glycosylation, which can influence their structure, physicochemical properties, intracellular transport, and function. Here, we systematically analyzed the functional relevance of N-linked glycans in the alphaherpesvirus pseudorabies virus (PrV) glycoprotein H (gH), which is an essential component of the conserved core herpesvirus fusion machinery. Upon gD-mediated receptor binding, the heterodimeric complex of gH and gL activates gB to mediate fusion of the viral envelope with the host cell membrane for viral entry. gH contains five potential N-linked glycosylation sites at positions 77, 162, 542, 604, and 627, which were inactivated by conservative mutations (asparagine to glutamine) singly or in combination. The mutated proteins were tested for correct expression and fusion activity. Additionally, the mutated gH genes were inserted into the PrV genome for analysis of function during virus infection. Our results demonstrate that all five sites are glycosylated. Inactivation of the PrV-specific N77 or the conserved N627 resulted in significantly reducedin vitrofusion activity, delayed penetration kinetics, and smaller virus plaques. Moreover, substitution of N627 greatly affected transport of gH in transfected cells, resulting in endoplasmic reticulum (ER) retention and reduced surface expression. In contrast, mutation of N604, which is conserved in theVaricellovirusgenus, resulted in enhancedin vitrofusion activity and viral cell-to-cell spread. These results demonstrate a role of the N-glycans in proper localization and function of PrV gH. However, even simultaneous inactivation of all five N-glycosylation sites of gH did not severely inhibit formation of infectious virus particles.IMPORTANCEHerpesvirus infection requires fusion of the viral envelope with cellular membranes, which involves the conserved fusion machinery consisting of gB and the heterodimeric gH/gL complex. The bona fide fusion protein gB depends on the presence of the gH/gL complex for activation. Viral envelope glycoproteins, such as gH, usually contain N-glycans, which can have a strong impact on their folding, transport, and functions. Here, we systematically analyzed the functional relevance of all five predicted N-linked glycosylation sites in the alphaherpesvirus pseudorabies virus (PrV) gH. Despite the fact that mutation of specific sites affected gH transport,in vitrofusion activity, and cell-to-cell spread and resulted in delayed penetration kinetics, even simultaneous inactivation of all five N-glycosylation sites of gH did not severely inhibit formation of infectious virus particles. Thus, our results demonstrate a modulatory but nonessential role of N-glycans for gH function.

The extracellular matrix of the developing cornea: diversity, deposition and function*

Development ◽  
1988 ◽  
Vol 103 (Supplement) ◽  
pp. 195-205
Author(s):  
J. B. L. Bard ◽  
M. K. Bansal ◽  
A. S. A. Ross
Keyword(s):  
Extracellular Matrix ◽  
Chondroitin Sulphate ◽  
Corneal Stroma ◽  
Experimental System ◽  
Collagen I ◽  
And Function ◽  
20 Nm

This paper examines the role of the extracellular matrix (ECM) in the development of the cornea. After a brief summary of the corneal structure and ECM, we describe evidence suggesting that the differentiation of neural crest (NC) cells into endothelium and fibroblasts is under the control of ocular ECM. We then examine the role of collagen I in stromal morphogenesis by comparing normal corneas with those of homozygous Movl3 mice which do not make collagen I. We report that, in spite of this absence, the cellular morphology of the Movl3 eye is indistinguishable from that of the wild type. In the 16-day mutant stroma, however, the remaining collagens form small amounts of disorganized, thin fibrils rather than orthogonally organized 20 nm-diameter fibrils; a result implying that collagen I plays only a structural role and that its absence is not compensated for. It also suggests that, because these remaining collagens will not form the normal fibrils that they will in vitro, fibrillogenesis in the corneal stroma differs from that elsewhere. The latter part of the paper describes our current work on chick stromal deposition using corneal epithelia isolated with an intact basal lamina that lay down in vitro ∼3μm-thick stromas of organized fibrils similar to that seen in vivo. This experimental system has yielded two unexpected results. First, the amount of collagen and proteoglycans produced by such epithelia is not dependent on whether its substratum is collagenous and we therefore conclude that stromal production by the intact epithelium is more autonomous than hitherto thought. Second, chondroitin sulphate (CS), the predominant proteoglycan, appears to play no role in stromal morphogenesis: epithelia cultured in testicular hyaluronidase, which degrades CS, lay down stromas whose organization and fibrildiameter distribution are indistinguishable from controls. One possible role for CS, however, is as a lubricant which facilitates corneal growth: it could allow fibrils to move over one another without deforming their orthogonal organization. Finally, we have examined the processes of fibrillogenesis in the corneal stroma and conclude that they are different from those elsewhere in the embryo and in vitro, perhaps because there is in the primary stroma an unidentified, highly hydrated ECM macromolecule that embeds the fibrils and that may mediate their morphogenesis.

Advances in aptamer evolution and engineering

2016 ◽  
Author(s):  
◽  
Khalid Kamal Alam
Keyword(s):  
High Throughput Sequencing ◽  
Target Selection ◽  
Three Dimensional ◽  
Rna Aptamers ◽  
Hiv Reverse Transcriptase ◽  
University Of Missouri ◽  
Selection Approach ◽  
And Function ◽  
The University

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Aptamers are single-stranded nucleic acids that fold into unique three-dimensional shapes that allow them to bind with high affinity and specificity to targets of interest. They are selected through the process of in vitro evolution, wherein large libraries of randomized sequence are iteratively partitioned and amplified to enrich for high-fitness, functional molecules. Selected libraries are sequenced and individual aptamers are characterized for their structure and function. Aptamers have found use as research tools, diagnostics, and therapeutics and in the control of biological systems. The work described herein presents several advancements to the selection and application of aptamers. I first describe an aptamer bioinformatics platform, FASTAptamer, which performs the primary sequence tasks common to all combinatorial selection techniques. I then describe a poly-target selection approach that leverages high-throughput sequencing, the aptamer bioinformatics platform, and parallel selections against a family of related targets to identify the first RNA aptamers capable of potent broad-spectrum inhibition of HIV reverse transcriptase. Finally, this work describes the engineering and in vitro validation of a bifurcated aptamer, Split-Broccoli, for direct visualization of RNA:RNA processes.

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