Rhoptry neck protein 2 expressed in
            
              Plasmodium
            
            sporozoites plays a crucial role during invasion of mosquito salivary glands

Saliva, a clear, tasteless, odourless, slightly acidic viscous extracellular fluid produced and secreted by salivary glands makes the oral cavity moist ; and has very important role is maintaining the well being of the mouth. Knowledge of the salivary system and saliva is essential for evaluating prosthodontic problems and for educating patients.

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Detection of the Rhoptry Neck Protein Complex in Plasmodium Sporozoites and Its Contribution to Sporozoite Invasion of Salivary Glands

mSphere ◽

10.1128/msphere.00325-20 ◽

2020 ◽

Vol 5 (4) ◽

Cited By ~ 1

Author(s):

Mamoru Nozaki ◽

Minami Baba ◽

Mayumi Tachibana ◽

Naohito Tokunaga ◽

Motomi Torii ◽

...

Keyword(s):

Salivary Glands ◽

Protein Complex ◽

Malaria Parasite ◽

Gene Knockdown ◽

Mammalian Host ◽

Target Cells ◽

Specific Gene ◽

Invasion Mechanisms ◽

Attachment Ability ◽

Rhoptry Neck Protein

ABSTRACT In the Plasmodium life cycle, two infectious stages of parasites, merozoites and sporozoites, share rhoptry and microneme apical structures. A crucial step during merozoite invasion of erythrocytes is the discharge to the host cell membrane of some rhoptry neck proteins as a complex, followed by the formation of a moving junction involving the parasite-secreted protein AMA1 on the parasite membrane. Components of the merozoite rhoptry neck protein complex are also expressed in sporozoites, namely, RON2, RON4, and RON5, suggesting that invasion mechanism elements might be conserved between these infective stages. Recently, we demonstrated that RON2 is required for sporozoite invasion of mosquito salivary gland cells and mammalian hepatocytes, using a sporozoite stage-specific gene knockdown strategy in the rodent malaria parasite model, Plasmodium berghei. Here, we use a coimmunoprecipitation assay and oocyst-derived sporozoite extracts to demonstrate that RON2, RON4, and RON5 also form a complex in sporozoites. The sporozoite stage-specific gene knockdown strategy revealed that both RON4 and RON5 have crucial roles during sporozoite invasion of salivary glands, including a significantly reduced attachment ability required for the onset of gliding. Further analyses indicated that RON2 and RON4 reciprocally affect trafficking to rhoptries in developing sporozoites, while RON5 is independently transported. These findings indicate that the interaction between RON2 and RON4 contributes to their stability and trafficking to rhoptries, in addition to involvement in sporozoite attachment. IMPORTANCE Sporozoites are the motile infectious stage that mediates malaria parasite transmission from mosquitoes to the mammalian host. This study addresses the question whether the rhoptry neck protein complex forms and functions in sporozoites, in addition to its role in merozoites. By applying coimmunoprecipitation and sporozoite stage-specific gene knockdown assays, it was demonstrated that RON2, RON4, and RON5 form a complex and are involved in sporozoite invasion of salivary glands via their attachment ability. These findings shed light on the conserved invasion mechanisms among apicomplexan infective stages. In addition, the sporozoite stage-specific gene knockdown system has revealed for the first time in Plasmodium that the RON2 and RON4 interaction reciprocally affects their stability and trafficking to rhoptries. Our study raises the possibility that the RON complex functions during sporozoite maturation as well as migration toward and invasion of target cells.

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Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080614 ◽

1977 ◽

Vol 35 ◽

pp. 638-639

Author(s):

P.J. Dailey

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Salivary Glands ◽

Secretory Vesicles ◽

The Past ◽

Transmission Electron ◽

Means Of Transmission ◽

Gromphadorhina Portentosa ◽

Scanning Electron ◽

Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

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Biogenesis of Catalase-Positive Rods in Excretory Duct Cells of Salivary Glands

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100090294 ◽

1976 ◽

Vol 34 ◽

pp. 62-63

Author(s):

Dwight K. Romanovicz ◽

Jacob S. Hanker

Keyword(s):

Light Microscopy ◽

Salivary Glands ◽

Submandibular Gland ◽

Excretory Duct ◽

Exocrine Glands ◽

Duct Cells ◽

Peroxidatic Activity ◽

Microscopic Studies ◽

Different Dimensions

The presence of catalase-positive rods (Fig. 1) of different dimensions, which frequently have a crystalline appearance by light microscopy, has been reported. They seem to be related to peroxisomes which were characterized morphologically and cytochemically in parotid and other exocrine glands of the rat by Hand in 1973. Our light microscopic studies of these spherical microbodies and rods of different sizes, stained by virtue of the peroxidatic activity of their catalase, indicate that they are almost entirely confined to the cells of the striated and execretory ducts of the submandibular gland in the mouse. The rods were usually noted only in the proximity of the ductal microbodies. The latter frequently showed a tendency to appear in linear close array, or even to be contiguous (Fig. 2). This suggested that the rods could be formed by the fusion of microbodies.

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An adrenocortical oncocytoma with unusual mitochondrial inclusions and cytoplasmic crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168980 ◽

1994 ◽

Vol 52 ◽

pp. 250-251

Author(s):

W.T. Gunning ◽

G.D. Haselhuhn ◽

E.R. Phillips ◽

S.H. Selman

Keyword(s):

Adrenal Gland ◽

Salivary Glands ◽

Mitotic Activity ◽

Diagnostic Criteria ◽

Vascular Invasion ◽

Benign Neoplasm ◽

Benign Tumors ◽

Nuclear Morphology ◽

Case Presentation ◽

Microscopic Evidence

Within the last few years, adrenal cortical tumors with features concordant with the diagnostic criteria attributed to oncocytomas have been reported. To date, only nine reported cases exist in the literature. This report is the tenth case presentation of a presumptively benign neoplasm of the adrenal gland with a rare differentiation. Oncocytomas are well recognized benign tumors of the thyroid, parathyroid, and salivary glands and of the kidney. Other organs also give rise to these types of tumors, however with less frequency than the former sites. The characteristics generally used to classify a tumor as an oncocytoma include the following criteria: the tumor is 1) usually a solitary circumscribed mass with no gross nor microscopic evidence of metastasis (no tissue nor vascular invasion), 2) fairly bland in terms of mitotic activity and nuclear morphology, and 3) composed of large eosinophillic cells in which the cytoplasm is packed full of mitochondria (Figure 1).

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