The schistosome in the mammalian host: understanding the mechanisms of adaptation

Parasitology ◽  
2007 ◽  
Vol 134 (11) ◽  
pp. 1477-1526 ◽  
Author(s):  
J. R. KUSEL ◽  
B. H. AL-ADHAMI ◽  
M. J. DOENHOFF
Keyword(s):  
Mammalian Cells ◽  
Surface Membrane ◽  
Membrane Rafts ◽  
Mammalian Host ◽  
Internal Organs ◽  
Parasite Communities ◽  
Mechanisms Of Adaptation ◽  
Future Work ◽  
The Relationship

SUMMARYIn this review, we envisage the host environment, not as a hostile one, since the schistosome thrives there, but as one in which the relationship between the two organisms consists of constant communication, through signalling mechanisms involving sense organs, surface glycocalyx, surface membrane and internal organs of the parasite, with host fluids and cells. The surface and secretions of the schistosome egg have very different properties from those of other parasite stages, but adapted for the dispersal of the eggs and for the preservation of host liver function. We draw from studies of mammalian cells and other organisms to indicate how further work might be carried out on the signalling function of the surface glycocalyx, the raft structure of the surface and existence of pores in the surface membrane, the repair of the surface membrane, the role of the membrane structure in ion channel function (including recent work on the actin cytoskeleton and calcium channels) and the possible role of P-glycoproteins in the adaptation of the parasite to its environment. We are speculative in some areas, such as the suggestions that variability in surface properties of schistosomes may relate to the existence of membrane rafts and that parasite communities may exhibit quorum sensing. This speculative approach is adopted with the hope that future work on the whole organisms and their interactions will be encouraged.

Antigenic variation in its biological context

1984 ◽  
Vol 307 (1131) ◽  
pp. 27-40 ◽  
Keyword(s):  
Salivary Glands ◽  
Antigenic Variation ◽  
Tsetse Fly ◽  
Mammalian Host ◽  
Full Understanding ◽  
Anamnestic Response ◽  
Insect Midgut ◽  
The Relationship ◽  
Biological Context

The biology of antigenic variation is discussed, and the problems that must be solved to provide a full understanding of antigenic variation are considered. These are (i) the induction of v.s.g. synthesis in the salivary glands of the tsetse fly; (ii) the nature of the restriction on v.s.g. genes that allows only some of them to be expressed in the salivary glands; (iii) the nature of ‘predominance’ in v.s.g. expression in the mammalian host, and the mechanism by which it operates; (iv) the repression of v.s.g. synthesis in the insect midgut; (v) the anamnestic response that produces expression of the ingested variant in the first patent parasitaemia in the mammalian host; (vi) the mechanism by which only one v.s.g. gene at a time is expressed; (vii) the relationship if any ofv.s.g. structure to v.s.g.-associated differences in growth rate and host range; (viii) the role of v.s.g. release within the life cycle and to pathogenesis.

scholarly journals The Role of Dimorphism Regulating Histidine Kinase (Drk1) in the Pathogenic Fungus Paracoccidioides brasiliensis Cell Wall

2021 ◽  
Vol 7 (12) ◽  
pp. 1014
Author(s):  
Marina Valente Navarro ◽  
Yasmin Nascimento de Barros ◽  
Wilson Dias Segura ◽  
Alison Felipe Alencar Chaves ◽  
Grasielle Pereira Jannuzzi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Histidine Kinase ◽  
Mammalian Cells ◽  
Paracoccidioides Brasiliensis ◽  
Pathogenic Fungus ◽  
Fungal Resistance ◽  
Phagocytic Index ◽  
Mammalian Host ◽  
Control Group

Dimorphic fungi of the Paracoccidioides genus are the causative agents of paracoccidioidomycosis (PCM), an endemic disease in Latin America with a high incidence in Brazil. This pathogen presents as infective mycelium at 25 °C in the soil, reverting to its pathogenic form when inhaled by the mammalian host (37 °C). Among these dimorphic fungal species, dimorphism regulating histidine kinase (Drk1) plays an essential role in the morphological transition. These kinases are present in bacteria and fungi but absent in mammalian cells and are important virulence and cellular survival regulators. Hence, the purpose of this study was to investigate the role of PbDrk1 in the cell wall modulation of P. brasiliensis. We observed that PbDrk1 participates in fungal resistance to different cell wall-disturbing agents by reducing viability after treatment with iDrk1. To verify the role of PbDRK1 in cell wall morphogenesis, qPCR results showed that samples previously exposed to iDrk1 presented higher expression levels of several genes related to cell wall modulation. One of them was FKS1, a β-glucan synthase that showed a 3.6-fold increase. Furthermore, confocal microscopy analysis and flow cytometry showed higher β-glucan exposure on the cell surface of P. brasiliensis after incubation with iDrk1. Accordingly, through phagocytosis assays, a significantly higher phagocytic index was observed in yeasts treated with iDrk1 than the control group, demonstrating the role of PbDrk1 in cell wall modulation, which then becomes a relevant target to be investigated. In parallel, the immune response profile showed increased levels of proinflammatory cytokines. Finally, our data strongly suggest that PbDrk1 modulates cell wall component expression, among which we can identify β-glucan. Understanding this signalling pathway may be of great value for identifying targets of antifungal molecular activity since HKs are not present in mammals.

The Role of Social Media in Adolescent Loneliness and Mental Health Problems: Current Evidence and Suggestions for Future Work

2021 ◽  
Author(s):  
Warner Myntti ◽  
Jensen Spicer ◽  
Carol Janney ◽  
Stacey Armstrong ◽  
Sarah Domoff
Keyword(s):  
Mental Health ◽  
Social Media ◽  
Mental Health Problems ◽  
Media Use ◽  
Current Evidence ◽  
Social Media Use ◽  
The Social ◽  
Future Work ◽  
The Relationship

Adolescents are spending more time interacting with peers online than in person, evidencing the need to examine this shift’s implications for adolescent loneliness and mental health. The current review examines research documenting an association between social media use and mental health, and highlights several specific areas that should be further explored as mechanisms within this relationship. Overall, it appears that frequency of social media use, the kind of social media use, the social environment, the platform used, and the potential for adverse events are especially important in understanding the relationship between social media use and adolescent mental health.

scholarly journals Toward a synthetic understanding of the role of phenology in ecology and evolution

2010 ◽  
Vol 365 (1555) ◽  
pp. 3101-3112 ◽  
Author(s):  
Jessica Forrest ◽  
Abraham J. Miller-Rushing
Keyword(s):  
Climate Change ◽  
Population Level ◽  
Annual Cycles ◽  
Biological Phenomena ◽  
Ecosystem Level ◽  
Modelling Techniques ◽  
Evolutionary Consequences ◽  
Future Work ◽  
The Relationship

Phenology affects nearly all aspects of ecology and evolution. Virtually all biological phenomena—from individual physiology to interspecific relationships to global nutrient fluxes—have annual cycles and are influenced by the timing of abiotic events. Recent years have seen a surge of interest in this topic, as an increasing number of studies document phenological responses to climate change. Much recent research has addressed the genetic controls on phenology, modelling techniques and ecosystem-level and evolutionary consequences of phenological change. To date, however, these efforts have tended to proceed independently. Here, we bring together some of these disparate lines of inquiry to clarify vocabulary, facilitate comparisons among habitat types and promote the integration of ideas and methodologies across different disciplines and scales. We discuss the relationship between phenology and life history, the distinction between organismal- and population-level perspectives on phenology and the influence of phenology on evolutionary processes, communities and ecosystems. Future work should focus on linking ecological and physiological aspects of phenology, understanding the demographic effects of phenological change and explicitly accounting for seasonality and phenology in forecasts of ecological and evolutionary responses to climate change.

Team identity in youth soccer: The role of coaches' feedback patterns and use of humour

2017 ◽  
Vol 12 (6) ◽  
pp. 697-707 ◽  
Author(s):  
Rune Høigaard ◽  
Tommy Haugen ◽  
Bjørn T Johansen ◽  
Rune Giske
Keyword(s):  
Structural Equation ◽  
Soccer Players ◽  
Instructive Feedback ◽  
Team Identity ◽  
Cross Sectional ◽  
Youth Soccer ◽  
Cross Sectional Design ◽  
Future Work ◽  
The Relationship

The purpose of this study was to empirically examine the relationship between coaches' communication patterns (feedback and use of humour) and team identity in youth soccer. A cross-sectional design was used and participants were 532 soccer players, aged from 13 to 20 years, taking part in a youth soccer tournament, the Sør Cup. Structural Equation Modelling based multiple regression analysis was conducted, and the findings revealed that positive/instructive feedback and coaches' use of humour were positive significant predictors of team identity. Contrary to our expectations, negative/punishment feedback was not significantly related to team identity. The findings are discussed within a social identity framework. It is concluded that positive/instructive feedback and the use of humour are elements that coaches may use to develop the team identity. However, future work is needed to further validate the scales used in this study, and to examine how the use of humour may influence the athlete and the team.

scholarly journals Role of Protein Glycosylation in Interactions of Medically Relevant Fungi with the Host

2021 ◽  
Vol 7 (10) ◽  
pp. 875
Author(s):  
Manuela Gómez-Gaviria ◽  
Ana P. Vargas-Macías ◽  
Laura C. García-Carnero ◽  
Iván Martínez-Duncker ◽  
Héctor M. Mora-Montes
Keyword(s):  
Protein Trafficking ◽  
Mammalian Cells ◽  
Fungal Infections ◽  
Fungal Species ◽  
Protein Glycosylation ◽  
Amino Acid Side Chain ◽  
Post Translational Modification ◽  
Fungal Cell ◽  
The Relationship

Protein glycosylation is a highly conserved post-translational modification among organisms. It plays fundamental roles in many biological processes, ranging from protein trafficking and cell adhesion to host–pathogen interactions. According to the amino acid side chain atoms to which glycans are linked, protein glycosylation can be divided into two major categories: N-glycosylation and O-glycosylation. However, there are other types of modifications such as the addition of GPI to the C-terminal end of the protein. Besides the importance of glycoproteins in biological functions, they are a major component of the fungal cell wall and plasma membrane and contribute to pathogenicity, virulence, and recognition by the host immunity. Given that this structure is absent in host mammalian cells, it stands as an attractive target for developing selective compounds for the treatment of fungal infections. This review focuses on describing the relationship between protein glycosylation and the host–immune interaction in medically relevant fungal species.

scholarly journals Antiviral Role of IFITM Proteins in Classical Swine Fever Virus Infection

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 126 ◽  
Author(s):  
Cheng Li ◽  
Hongqing Zheng ◽  
Yifan Wang ◽  
Wang Dong ◽  
Yaru Liu ◽  
...  
Keyword(s):  
Classical Swine Fever Virus ◽  
Mammalian Cells ◽  
Classical Swine Fever ◽  
Fever Virus ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Infected Cells ◽  
The Relationship ◽  
Antiviral Role

The proteins IFITM1, IFITM2, and IFITM3 are host effectors against a broad range of RNA viruses whose roles in classical swine fever virus (CSFV) infection had not yet been reported. We investigated the effect of these proteins on CSFV replication in mammalian cells. The proteins were overexpressed and silenced using lentiviruses. Confocal microscopy was used to determine the distribution of these proteins in the cells, and immunofluorescence colocalization analysis was used to evaluate the relationship between IFITMs and the CSFV endosomal pathway, including early endosomes, late endosomes, and lysosomes. IFITM1, IFITM2, or IFITM3 overexpression significantly inhibited CSFV replication, whereas protein knockdown enhanced CSFV replication. In porcine alveolar macrophages (PAMs), IFITM1 was mainly located at the cell surface, whereas IFITM2 and IFITM3 were mainly located in the cytoplasm. Following CSFV infection, the distribution of IFITM1 changed. IFITM1, IFITM2, and IFITM3 colocalization with Lamp1, IFITM2 with Rab5 and Rab7, and IFITM3 with Rab7 were observed in CSFV-infected cells. Collectively, these results provide insights into the possible mechanisms associated with the anti-CSFV action of the IFITM family.

scholarly journals Asymmetric Requirement for Cholesterol in Receptor-Bearing but Not Envelope-Bearing Membranes for Fusion Mediated by Ecotropic Murine Leukemia Virus

2002 ◽  
Vol 76 (13) ◽  
pp. 6701-6709 ◽  
Author(s):  
Xiongbin Lu ◽  
Ying Xiong ◽  
Jonathan Silver
Keyword(s):  
Murine Leukemia Virus ◽  
Mammalian Cells ◽  
Insect Cells ◽  
Leukemia Virus ◽  
Cell System ◽  
Membrane Rafts ◽  
Cell Physiology ◽  
Virus Envelope ◽  
Murine Leukemia

ABSTRACT We show that fusion mediated by ecotropic murine leukemia virus envelope is dependent on cholesterol in receptor-bearing membranes. The effect is >10 times larger in insect cells than mammalian cells, probably because the former can be more extensively depleted of cholesterol. The fact that cholesterol is apparently not needed in envelope-bearing membranes suggests that it plays a role in an asymmetric step in membrane fusion and argues against a class of models in which cholesterol is important in symmetric fusion intermediates. The insect cell system has promise for clarifying the role of membrane rafts in other aspects of cell physiology.

The role of hypoxia in the integrity of the genetic apparatus and the formation of memory in drosophila in the paradigm of conditioned reflex suppression of courtship

2021 ◽  
Vol 20 (4) ◽  
pp. 45-54
Author(s):  
Anna V. Medvedeva ◽  
Elena V. Tokmacheva ◽  
Ekaterina A. Nikitina ◽  
Svetlana Alexandrovna Vasilieva ◽  
Ekaterina S. Zalomaeva ◽  
...  
Keyword(s):  
Nervous System ◽  
Conditioned Reflex ◽  
Nervous Activity ◽  
Hypoxic Exposure ◽  
Experimental Conditions ◽  
Adaptive Capabilities ◽  
Mechanisms Of Adaptation ◽  
The Relationship ◽  
Conditioned Connection

M.E. Lobashev and V.В. Savvateev in 1959 obtained unique data on the expansion of the adaptive capabilities of the organism when training the properties of higher nervous activity by the formation of conditioned food reflexes to stimuli that exhaust the nervous system. Apparently, the formation of a conditioned connection help to overcoming stressful effects, adaptation to restrictive conditions, and changes in the functioning of the nervous system. To test this assumption, the influence of stressful influences hypoxia on learning and memory of Drosophila in the paradigm of conditioned reflex suppression of courtship was studied. The results were obtained on the enhancement of the ability to learn under hypoxic exposure. These experimental conditions did not affect memory formation. The effect of hypoxia on chromosomes through the formation of double-stranded breaks was revealed. The data are discussed in light of the relationship between neuroplasticity processes and mechanisms of adaptation to stressors.

scholarly journals Evidence for the participation of the Ssp-3 antigen in the invasion of nonphagocytic mammalian cells by Trypanosoma cruzi.

1992 ◽  
Vol 175 (6) ◽  
pp. 1635-1641 ◽  
Author(s):  
S Schenkman ◽  
T Kurosaki ◽  
J V Ravetch ◽  
V Nussenzweig
Keyword(s):  
Monoclonal Antibodies ◽  
Trypanosoma Cruzi ◽  
Mammalian Cells ◽  
Surface Membrane ◽  
Fc Receptors ◽  
Transfected Cells ◽  
3T3 Fibroblasts ◽  
Parallel Increase ◽  
Membrane Antigens

Trypomastigotes of Trypanosoma cruzi have to invade mammalian cells in order to multiply. They bear on their plasma membrane a sialic acid-containing epitope (Ssp-3) defined by a series of monoclonal antibodies (mAbs). Previous investigations have shown that Fab fragments of these mAbs inhibit the attachment of trypomastigotes to 3T3 fibroblasts. To further define the role of Ssp-3 in invasion, here we use, as targets for infection, L cells and CHO cells stably transfected with cDNA coding for the mouse Fc receptors genes. When the trypomastigotes are incubated with small, nonagglutinating amounts of antibodies to Ssp-3, their attachment to the transfected cells is greatly enhanced, without a parallel increase in invasion. The enhancement in attachment is Fc mediated, since it is abolished by treatment of the transfected cells with mAbs to Fc receptors. In contrast, both attachment to, and invasion of, the transfected cells are increased if the parasites are incubated with polyclonal or monoclonal antibodies against T. cruzi surface membrane antigens other than Ssp-3. If, however, antibodies to Ssp-3 are added to the incubation mixtures containing any of the other anti-T. cruzi antibodies, the enhancement of invasion (but not of attachment) is reversed. These results suggest that Ssp-3-bearing molecules participate in the process of parasite internalization.

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