scholarly journals Malaria transmission relies on concavin-mediated maintenance of Plasmodium sporozoite cell shape

2021 ◽  
Author(s):  
Jessica Kehrer ◽  
Pauline Formaglio ◽  
Julianne Mendi Muthinja ◽  
Sebastian Weber ◽  
Danny Baltissen ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Blood Vessel ◽  
Salivary Glands ◽  
Cell Shape ◽  
Transmission Efficiency ◽  
Membrane Complex ◽  
Migratory Speed ◽  
Pass Through ◽  
Inner Membrane Complex ◽  
Considerable Strain

During transmission of malaria-causing parasites from mosquitoes to mammals, Plasmodium sporozoites migrate rapidly in the skin to search for a blood vessel. The high migratory speed and narrow passages taken by the parasites suggest considerable strain on the sporozoites to maintain their shape. Here we report on a newly identified protein, concavin, that is important for maintenance of the sporozoite shape inside salivary glands of mosquitoes and during migration in the skin. Concavin-GFP localized at the cytoplasmic periphery of sporozoites and concavin(-) sporozoites progressively rounded up upon entry of salivary glands. These rounded concavin(-) sporozoites failed to pass through the narrow salivary ducts and were hence rarely ejected by mosquitoes. However, normally shaped concavin(-) sporozoites could be transmitted and migrated in the skin or skin like environments. Strikingly, motile concavin(-) sporozoites could disintegrate while migrating through narrow strictures in the skin leading to parasite arrest or death and decreased transmission efficiency. We suggest that concavin contributes to cell shape maintenance by riveting the plasma membrane to the subtending inner membrane complex.

scholarly journals A malaria membrane skeletal protein is essential for normal morphogenesis, motility, and infectivity of sporozoites

2004 ◽  
Vol 167 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Emad I. Khater ◽  
Robert E. Sinden ◽  
Johannes T. Dessens
Keyword(s):  
Cell Shape ◽  
Mechanical Stability ◽  
Membrane Skeleton ◽  
Apicomplexan Parasites ◽  
Membrane Complex ◽  
Skeletal Protein ◽  
Complex Protein ◽  
Parasite Biology ◽  
Inner Membrane Complex ◽  
Membrane Skeletons

Membrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei, we show that PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology.

An Ultrastructural Study of Pericytes

1968 ◽  
Vol 26 ◽  
pp. 66-67
Author(s):  
T. M. Murad ◽  
E. von Haam
Keyword(s):  
Plasma Membrane ◽  
Endothelial Cell ◽  
Basement Membrane ◽  
Blood Vessel ◽  
Vascular Endothelial Cells ◽  
Myoepithelial Cells ◽  
Capillary Blood ◽  
The Body ◽  
Capillary Blood Vessel ◽  
Outer Plasma Membrane

Pericytes are vascular satellites present around capillary blood vessels and small venules. They have been observed in almost every tissue of the body and are thought to be related to vascular smooth muscle cells. Morphologically pericytes have great similarity to vascular endothelial cells and also slightly resemble myoepithelial cells.The present study describes the ultrastructural morphology of pericytes in normal breast tissue and in benign tumor of the breast. The study showed that pericytes are ovoid or elongated cells separated from the endothelial cell of the capillary blood vessel by the basement membrane of endothelial cell. The nuclei of pericytes are often very distinctive. Although some are round, oval, or elongated, others show marked irregularity and infolding of the nuclear membrane. The cytoplasm shows mono-or bipolar extension in which the cytoplasmic organelles are located (Fig. 1). These cytoplasmic extensions embrace the capillary blood vessel incompletely. The plasma membrane exhibits multiple areas of focal condensation called hemidesmosomes (Fig. 2, arrow). A variable number of pinocytotic vesicles are frequently seen lining the outer plasma membrane. Normally pericytes are surrounded by a basement membrane which is found more consistently on the outer plasma membrane separating the pericytes from the stromal connective tissue.

Immunocytochemical localization of p65 with one-nanometer gold particles following silver development

1989 ◽  
Vol 47 ◽  
pp. 1042-1043
Author(s):  
Richard W. Burry ◽  
Diane M. Hayes
Keyword(s):  
Plasma Membrane ◽  
Bovine Serum Albumin ◽  
Calf Serum ◽  
Specific Protein ◽  
Immunocytochemical Localization ◽  
Electron Microscopic ◽  
Gold Particles ◽  
Pass Through ◽  
Label Distribution ◽  
Phosphate Buffered Saline

Electron microscopic (EM) immunocytochemistry localization of the neuron specific protein p65 could show which organelles contain this antigen. Antibodies (Ab) labeled with horseradish peroxidase (HRP) followed by chromogen development show a broad diffuse label distribution within cells and restricting identification of organelles. Particulate label (e.g. 10 nm colloidal gold) is highly desirable but not practical because penetration into cells requires destroying the plasma membrane. We report pre-embedding immunocytochemistry with a particulate marker, 1 nm gold, that will pass through membranes treated with saponin, a mild detergent.Cell cultures of the rat cerebellum were fixed in buffered 4% paraformaldehyde and 0.1% glutaraldehyde (Glut.). The buffer for all incubations and rinses was phosphate buffered saline with: 1% calf serum, 0.2% saponin, 0.1% gelatin, 50 mM glycine 1 mg/ml bovine serum albumin, and (not in the HRP labeled cultures) 0.02% sodium azide. The monoclonal #48 to p65 was used with three label systems: HRP, 1 nm avidin gold with IntenSE M development, and 1 nm avidin gold with Danscher development.

scholarly journals Raft microdomain localized in the luminal leaflet of inner membrane complex of living Toxoplasma gondii

2021 ◽  
Vol 100 (2) ◽  
pp. 151149
Author(s):  
Rikako Konishi ◽  
Yuna Kurokawa ◽  
Kanna Tomioku ◽  
Tatsunori Masatani ◽  
Xuenan Xuan ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Inner Membrane Complex

scholarly journals The Genes raw and ribbon Are Required for Proper Shape of Tubular Epithelial Tissues in Drosophila

Genetics ◽  
1997 ◽  
Vol 147 (1) ◽  
pp. 243-253 ◽  
Author(s):  
Joseph Jack ◽  
Guy Myette
Keyword(s):  
Embryonic Development ◽  
Salivary Glands ◽  
Cell Shape ◽  
Malpighian Tubules ◽  
Dorsal Closure ◽  
Epithelial Tissues ◽  
Cell Rearrangement

Abstract The products of two genes, raw and ribbon (rib), are required for the proper morphogenesis of a variety of tissues. Malpighian tubules mutant for raw or rib are wider and shorter than normal tubules, which are only two cells in circumference when they are fully formed. The mutations alter the shape of the tubules beginning early in their formation and block cell rearrangement late in development, which normally lengthens and narrows the tubes. Mutations of both genes affect a number of other tissues as well. Both genes are required for dorsal closure and retraction of the CNS during embryonic development. In addition, rib mutations block head involution, and broaden and shorten other tubular epithelia (salivary glands, tracheae, and hindgut) in much same manner as they alter the shape of the Malpighian tubules. In tissues in which the shape of cells can be observed readily, rib mutations alter cell shape, which probably causes the change in shape of the organs that are affected. In double mutants raw enhances the phenotypes of all the tissues that are affected by rib but unaffected by raw alone, indicating that raw is also active in these tissues.

scholarly journals Toxoplasma gondii myosins B/C

2001 ◽  
Vol 155 (4) ◽  
pp. 613-624 ◽  
Author(s):  
Frédéric Delbac ◽  
Astrid Sänger ◽  
Eva M. Neuhaus ◽  
Rolf Stratmann ◽  
James W. Ajioka ◽  
...  
Keyword(s):  
Cell Division ◽  
Toxoplasma Gondii ◽  
Daughter Cell ◽  
Gliding Motility ◽  
Apicomplexan Parasites ◽  
Daughter Cells ◽  
Membrane Complex ◽  
Alternatively Spliced ◽  
Butanedione Monoxime ◽  
Inner Membrane Complex

In apicomplexan parasites, actin-disrupting drugs and the inhibitor of myosin heavy chain ATPase, 2,3-butanedione monoxime, have been shown to interfere with host cell invasion by inhibiting parasite gliding motility. We report here that the actomyosin system of Toxoplasma gondii also contributes to the process of cell division by ensuring accurate budding of daughter cells. T. gondii myosins B and C are encoded by alternatively spliced mRNAs and differ only in their COOH-terminal tails. MyoB and MyoC showed distinct subcellular localizations and dissimilar solubilities, which were conferred by their tails. MyoC is the first marker selectively concentrated at the anterior and posterior polar rings of the inner membrane complex, structures that play a key role in cell shape integrity during daughter cell biogenesis. When transiently expressed, MyoB, MyoC, as well as the common motor domain lacking the tail did not distribute evenly between daughter cells, suggesting some impairment in proper segregation. Stable overexpression of MyoB caused a significant defect in parasite cell division, leading to the formation of extensive residual bodies, a substantial delay in replication, and loss of acute virulence in mice. Altogether, these observations suggest that MyoB/C products play a role in proper daughter cell budding and separation.

scholarly journals A novel DNA-binding protein regulates sexual differentiation in malaria parasites and is essential for transmission

2020 ◽  
Author(s):  
Riward Campelo Morillo ◽  
Xinran Tong ◽  
Wei Xie ◽  
Todd Lenz ◽  
Gayani Batugedara ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Sexual Differentiation ◽  
Binding Protein ◽  
Dna Binding Protein ◽  
Homeodomain Protein ◽  
Mosquito Vector ◽  
Malaria Parasites ◽  
Membrane Complex ◽  
Inner Membrane Complex

ABSTRACTTransmission of Plasmodium falciparum and other malaria parasites requires their differentiation from asexual blood stages into gametocytes, the non-replicative sexual stage necessary for transmission to the mosquito vector. This transition involves changes in gene expression and chromatin reorganization mediating the silencing and activation of stage-specific genes. However, malaria parasites have been noted for their dearth of transcriptional and chromatin regulators and the molecular mediators of these changes remain largely unknown. We identified Homeodomain protein 1 (HDP1) as a novel chromatin-associated DNA-binding protein that drives changes in chromatin structure and gene expression during early sexual differentiation. This discovery of a homeodomain-like DNA-binding protein marks a new class of transcriptional regulator in malaria parasites outside of the better-characterized ApiAP2 family. In this study, we demonstrate that HDP1 is required for gametocyte maturation and parasite transmission by driving the necessary upregulation of inner membrane complex components in early gametocytes.

scholarly journals Metamorphoses of malaria: the role of autophagy in parasite differentiation

2011 ◽  
Vol 51 ◽  
pp. 127-136 ◽  
Author(s):  
Isabelle Coppens
Keyword(s):  
Life Cycle ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Protozoan Parasites ◽  
Membrane Complex ◽  
Autophagic Process ◽  
Inner Membrane Complex ◽  
Form Development ◽  
High Degree

Several protozoan parasites undergo a complex life cycle that alternates between an invertebrate vector and a vertebrate host. Adaptations to these different environments by the parasites are achieved by drastic changes in their morphology and metabolism. The malaria parasites must be transmitted to a mammal from a mosquito as part of their life cycle. Upon entering the mammalian host, extracellular malaria sporozoites reach the liver and invade hepatocytes, wherein they meet the challenge of becoming replication-competent schizonts. During the process of conversion, the sporozoite selectively discards organelles that are unnecessary for the parasite growth in liver cells. Among the organelles that are cleared from the sporozoite are the micronemes, abundant secretory vesicles that facilitate the adhesion of the parasite to hepatocytes. Organelles specialized in sporozoite motility and structure, such as the inner membrane complex (a major component of the motile parasite's cytoskeleton), are also eliminated from converting parasites. The high degree of sophistication of the metamorphosis that occurs at the onset of the liver-form development cascade suggests that the observed changes must be multifactorial. Among the mechanisms implicated in the elimination of sporozoite organelles, the degradative process called autophagy contributes to the remodelling of the parasite interior and the production of replicative liver forms. In a broader context, the importance of the role played by autophagy during the differentiation of protozoan parasites that cycle between insects and vertebrates is nowadays clearly emerging. An exciting prospect derived from these observations is that the parasite proteins involved in the autophagic process may represent new targets for drug development.

Sign in / Sign up

Export Citation Format

Share Document