Ontogeny of lipid bodies in the endoplasmic reticulum of Fusarium sulphureum

1977 ◽  
Vol 23 (2) ◽  
pp. 190-196
Author(s):  
Edward F. Schneider ◽  
W. L. Seaman
Keyword(s):  
Endoplasmic Reticulum ◽  
Higher Plants ◽  
Broad Band ◽  
Lipid Body ◽  
Lipid Bodies ◽  
Unit Membrane ◽  
Electron Dense Material ◽  
Fusarium Sulphureum ◽  
Body Development ◽  
Adverse Environmental Conditions

The ontogeny of lipid bodies during the differentiation of conidial cells to chlamydospores in Fusarium sulphureum (F. sambucinum f. 6) is described. The lipid bodies are first seen as electron-transparent areas within dilated cisternae of the endoplasmic reticulum (ER). One or more such cisternae may be formed within a strand of ER. The intracisternal lipid bodies are bounded by a unit membrane derived from the double membrane of the ER. The dilated cisternae increase in size and remain electron-transparent; however, some electron-dense granular material is present in the lipid bodies. The limiting unit membrane is visible throughout development of the lipid body; however, in mature chlamydospores the membrane is obscured by a broad band of electron-dense material which may provide protection to the stored lipids during adverse environmental conditions. The system of lipid body development in F. sulphureum is discussed in relation to those described for higher plants.

The ultrastructure of the R.S. zoospore of the Chytridiomycete Physoderma gerhardti

1978 ◽  
Vol 56 (12) ◽  
pp. 1387-1393 ◽  
Author(s):  
Robert J. Lowry ◽  
Frederick K. Sparrow
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Inclusion Bodies ◽  
Smooth Endoplasmic Reticulum ◽  
Lipid Body ◽  
Dense Material ◽  
Electron Dense Material ◽  
General Internal ◽  
Deep Groove ◽  
Posterior Flagellum

The fine structure of the zoospore of Physoderma gerhardti Schroeter is described. It possesses a single very large lipid body (sometimes accompanied by several smaller ones) situated laterally to the nuclear cap – nucleus complex and is associated with electron-dense material (the microbody) and the single large posteriorly located mitochondrion. The single posterior flagellum proximally terminates in a kinetosome just short of the posterior cone-shaped end of the nucleus. The kinetosome lies in a deep groove in the mitochondrion and is associated with this organelle by striated rootlets. The kinetosome terminates in electron-dense material from which an array of microtubules arises. These microtubules run along the sides of the cone-shaped nucleus and nuclear cap. There is an accessory centriole lying close to and more or less parallel with the kinetosome. The cytoplasm contains a small amount of smooth endoplasmic reticulum and several inclusion bodies in the anterior region and several small vacuoles in the posterior region of the cell. The general internal organization of the zoospore of Physoderma gerhardti more nearly resembles that of a blastocladiaceous fungus than of any chytrid thus far investigated.

scholarly journals The Rhodococcus opacus PD630 Heparin-Binding Hemagglutinin Homolog TadA Mediates Lipid Body Formation

2010 ◽  
Vol 76 (21) ◽  
pp. 7217-7225 ◽  
Author(s):  
Daniel P. MacEachran ◽  
M. E. Prophete ◽  
A. J. Sinskey
Keyword(s):  
Kinetic Studies ◽  
Lipid Body ◽  
Dry Weight ◽  
Rhodococcus Opacus ◽  
Lipid Bodies ◽  
Heparin Binding ◽  
Tag Biosynthesis ◽  
Tag Accumulation

ABSTRACT Generally, prokaryotes store carbon as polyhydroxyalkanoate, starch, or glycogen. The Gram-positive actinomycete Rhodococcus opacus strain PD630 is noteworthy in that it stores carbon in the form of triacylglycerol (TAG). Several studies have demonstrated that R. opacus PD630 can accumulate up to 76% of its cell dry weight as TAG when grown under nitrogen-limiting conditions. While this process is well studied, the underlying molecular and biochemical mechanisms leading to TAG biosynthesis and subsequent storage are poorly understood. We designed a high-throughput genetic screening to identify genes and their products required for TAG biosynthesis and storage in R. opacus PD630. We identified a gene predicted to encode a putative heparin-binding hemagglutinin homolog, which we have termed tadA (triacylglycerol accumulation deficient), as being important for TAG accumulation. Kinetic studies of TAG accumulation in both the wild-type (WT) and mutant strains demonstrated that the tadA mutant accumulates 30 to 40% less TAG than the parental strain (WT). We observed that lipid bodies formed by the mutant strain were of a different size and shape than those of the WT. Characterization of TadA demonstrated that the protein is capable of binding heparin and of agglutinating purified lipid bodies. Finally, we observed that the TadA protein localizes to lipid bodies in R. opacus PD630 both in vivo and in vitro. Based on these data, we hypothesize that the TadA protein acts to aggregate small lipid bodies, found in cells during early stages of lipid storage, into larger lipid bodies and thus plays a key role in lipid body maturation in R. opacus PD630.

scholarly journals The P5A ATPase Spf1p is stimulated by phosphatidylinositol 4-phosphate and influences cellular sterol homeostasis

2019 ◽  
Vol 30 (9) ◽  
pp. 1069-1084 ◽  
Author(s):  
Danny Mollerup Sørensen ◽  
Henrik Waldal Holen ◽  
Jesper Torbøl Pedersen ◽  
Helle Juel Martens ◽  
Daniele Silvestro ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Marked Change ◽  
Hydrolytic Activity ◽  
Genetic Interactions ◽  
Eukaryotic Cells ◽  
Lipid Bodies ◽  
Increased Sensitivity ◽  
Phosphatidylinositol 4 ◽  
P Type

P5A ATPases are expressed in the endoplasmic reticulum (ER) of all eukaryotic cells, and their disruption results in severe ER stress. However, the function of these ubiquitous membrane proteins, which belong to the P-type ATPase superfamily, is unknown. We purified a functional tagged version of the Saccharomyces cerevisiae P5A ATPase Spf1p and observed that the ATP hydrolytic activity of the protein is stimulated by phosphatidylinositol 4-phosphate (PI4P). Furthermore, SPF1 exhibited negative genetic interactions with SAC1, encoding a PI4P phosphatase, and with OSH1 to OSH6, encoding Osh proteins, which, when energized by a PI4P gradient, drive export of sterols and lipids from the ER. Deletion of SPF1 resulted in increased sensitivity to inhibitors of sterol production, a marked change in the ergosterol/lanosterol ratio, accumulation of sterols in the plasma membrane, and cytosolic accumulation of lipid bodies. We propose that Spf1p maintains cellular sterol homeostasis by influencing the PI4P-induced and Osh-mediated export of sterols from the ER.

The Oxygen-Dependent Modification of Triacylglycerols and Phospholipids, the Different Way of Initiating Lipid Body Mobilization

1997 ◽  
Vol 52 (1-2) ◽  
pp. 1-8 ◽  
Author(s):  
Helmut Kindi
Keyword(s):  
Cucumis Sativus ◽  
Intracellular Localization ◽  
Lipid Body ◽  
Chemical Mechanism ◽  
Lipid Bodies ◽  
Important Process ◽  
Lipid Mobilization ◽  
Phospholipid Monolayer ◽  
Dependent Modification ◽  
Plant Seedlings

For plant seedlings dependent on the breakdown of lipid reserves for gluconeogenesis the onset of lipid mobilization is a critically important process. Until recently, knowledge about the chemical mechanism of the initial breakdown steps has been limited, because the lipolytic activities, characterized by the intracellular localization and the type of substrate, have not always been found. As seedlings that depend on the reserves in lipid bodies may differ in morphology and biochemistry, it is likely that more than one pathway exists. Recent studies with cucumber (Cucumis sativus) cotyledons have shown that a lipid body-associated lipoxygenase, and an O2-dependent reaction, initiate both the destabilization of the phospholipid monolayer and the breakdown of triglycerides. Both types of reactions rely on the particular properties of a lipoxygenase isoform exclusively present in lipid bodies.

Calreticulin, a multifunctional Ca2+ binding chaperone of the endoplasmic reticulum

1998 ◽  
Vol 76 (5) ◽  
pp. 779-785 ◽  
Author(s):  
Marek Michalak ◽  
Paola Mariani ◽  
Michal Opas
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Posttranslational Modification ◽  
Storage Capacity ◽  
Higher Plants ◽  
Plant Cells ◽  
Steroid Sensitive ◽  
Endoplasmic Reticulum Chaperone ◽  
Precise Role ◽  
Cellular Ca

Calreticulin is a ubiquitous endoplasmic reticulum Ca2+ binding chaperone. The protein has been implicated in a variety of diverse functions. Calreticulin is a lectin-like chaperone and, together with calnexin, it plays an important role in quality control during protein synthesis, folding, and posttranslational modification. Calreticulin binds Ca2+ and affects cellular Ca2+ homeostasis. The protein increases the Ca2+ storage capacity of the endoplasmic reticulum and modulates the function of endoplasmic reticulum Ca2+-ATPase. Calreticulin also plays a role in the control of cell adhesion and steroid-sensitive gene expression. Recently, the protein has been identified and characterized in higher plants but its precise role in plant cells awaits further investigation.Key words: calreticulin, endoplasmic reticulum, chaperone, Ca2+ binding protein.

Elektronenmikroskopische Untersuchungen über die Eizellbildung und Eizellreifung des Lebermooses Sphaerocarpus donnellii Aust.

1965 ◽  
Vol 20 (8) ◽  
pp. 795-801 ◽  
Author(s):  
Lothar Diers
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Phase Contrast ◽  
Lipid Droplets ◽  
Unit Membrane ◽  
Light Phase ◽  
Lamellar System ◽  
Small Bodies ◽  
Canal Cell ◽  
Ventral Canal

The formation and maturation of the egg of the liverwort, Sphaerocarpus donnellii, was investigated by light, phase contrast and particularly by electron microscopy. The division of the central cell into the egg and the ventral canal cell, and the maturation of the egg, is completed within four days. All stages of this formation and maturation were examined under the electron microscope after fixation in KMnO4 or OsO4. — In the maturing egg there always occur the endoplasmic reticulum, well recognisable plastids with a poorly developed lamellar system, numerous mitochondria and dictyosomes, a rising number of lipid droplets, unknown small bodies limited by a unit membrane, and numerous ribosomes. During maturation the nucleus considerably enlarges and forms evaginations into the cytoplasm. Starch is increasingly deposited in the plastids. A degeneration of plastids has not been found.

scholarly journals Development of Embryo Suspensors for Five Genera of Crassulaceae with Special Emphasis on Plasmodesmata Distribution and Ultrastructure

Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 320 ◽  
Author(s):  
Małgorzata Kozieradzka-Kiszkurno ◽  
Daria Majcher ◽  
Emilia Brzezicka ◽  
Joanna Rojek ◽  
Justyna Wróbel-Marek ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Basal Cell ◽  
Lipid Droplets ◽  
Cell Structure ◽  
Cell Transfer ◽  
Electron Dense Material ◽  
Full Development ◽  
The One ◽  
Embryonic Structure ◽  
Suspensor Cells

The suspensor in the majority of angiosperms is an evolutionally conserved embryonic structure functioning as a conduit that connects ovule tissues with the embryo proper for nutrients and growth factors flux. This is the first study serving the purpose of investigating the correlation between suspensor types and plasmodesmata (PD), by the ultrastructure of this organ in respect of its full development. The special attention is paid to PD in representatives of Crassulaceae genera: Sedum, Aeonium, Monanthes, Aichryson and Echeveria. The contribution of the suspensor in transporting nutrients to the embryo was confirmed by the basal cell structure of the suspensor which produced, on the micropylar side of all genera investigated, a branched haustorium protruding into the surrounding ovular tissue and with wall ingrowths typically associated with cell transfer. The cytoplasm of the basal cell was rich in endoplasmic reticulum, mitochondria, dictyosomes, specialized plastids, microtubules, microbodies and lipid droplets. The basal cell sustained a symplasmic connection with endosperm and neighboring suspensor cells. Our results indicated the dependence of PD ultrastructure on the type of suspensor development: (i) simple PD are assigned to an uniseriate filamentous suspensor and (ii) PD with an electron-dense material are formed in a multiseriate suspensor. The occurrence of only one or both types of PD seems to be specific for the species but not for the genus. Indeed, in the two tested species of Sedum (with the distinct uniseriate/multiseriate suspensors), a diversity in the structure of PD depends on the developmental pattern of the suspensor. In all other genera (with the multiseriate type of development of the suspensor), the one type of electron-dense PD was observed.

ULTRASTRUCTURE OF THE HYPHAE AND HAUSTORIA OF PHYTOPHTHORA INFESTANS AND HYPHAE OF P. PARASITICA

1966 ◽  
Vol 44 (11) ◽  
pp. 1495-1503 ◽  
Author(s):  
Mary A. Ehrlich ◽  
Howard G. Ehrlich
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Phytophthora Infestans ◽  
Current Literature ◽  
Lipid Bodies ◽  
Potato Varieties ◽  
Parasitic Fungi ◽  
Obligate Parasites ◽  
Tubular Endoplasmic Reticulum ◽  
Cytoplasmic Continuity

The ultrastructure of the mycelium of both Phytophthora infestans and P. parasitica is consistent with that reported for other Oomycetes. A distinct plasmalemma, porate nuclei, tubular endoplasmic reticulum, mitochondria with tubular cristae, Golgi dictyosomes, and lipid bodies are present within the protoplast. The haustoria produced by P. infestans in the leaves of susceptible potato varieties consist of an expanded haustorial head surrounded by a fungus wall which is continuous with the wall of the intercellular mycelium. The haustorium lacks the long narrow stalk or neck often associated with this organ, and there is considerable cytoplasmic continuity between the haustorium and the intercellular mycelium. All P. infestans haustoria observed were anucleate and generally contained only a few mitochondria and sparse endoplasmic reticulum. The haustorium is enclosed in an encapsulation surrounded by a membrane which is continuous with the host plasmalemma. There is no evidence, around any portion of the haustorium, of a sheath originating from the cell wall of the host. A survey of the current literature on the ultrastructure of the Eumycotinia shows that the parasitic fungi exhibit no unique cytoplasmic features when compared with non-parasitic fungi, and the ultrastructure of the haustoria-producing facultative saprophyte is similar to that of the obligate parasites.

Origine et formation de différents types de vacuoles induites par la multiplication d'Alphavirus Sindbis dans divers systemes cellulaires

1979 ◽  
Vol 25 (12) ◽  
pp. 1452-1459 ◽  
Author(s):  
Yves Lombard ◽  
Philippe Poindron ◽  
Aimé Porte
Keyword(s):  
Endoplasmic Reticulum ◽  
Glial Cells ◽  
Chicken Embryo ◽  
Cytoplasmic Membrane ◽  
Dense Material ◽  
Newborn Mice ◽  
Electron Dense Material ◽  
Double Membrane ◽  
Single Membrane ◽  
Chicken Embryo Fibroblasts

Spherule-containing vacuoles and nucleocapsid-bearing vacuoles (cytopathic vacuoles types 1 and 2 respectively of Grimley et al. 1968) induced by Alphavirus Sindbis were studied in brains from newborn mice, chicken embryo fibroblasts, and two lines of tumoral glial cells from muridae. Endoplasmic reticulum (ER) elements and finely granular electron-dense material also seen in contact with nucleocapsids seemed to be involved in the formation of the classical single-membrane spherule-containing vacuoles. A second type of spherule-containing vacuoles were characterized by their double membrane and an amorphous electron-dense content and were probably derived from mitochondria. Nucleocapsid-bearing vacuoles were formed from modified ER elements and seemed to be linked to excessive synthesis of viral material. Such ER alterations were not observed in RG6 cells. In these cells, there were only spherule-containing vacuoles, while nucleocapsids were seen associated with the cytoplasmic membrane only.

The ultrastructure of a haemogregarine parasitic in Gehyra variegata (Duméril & Bibron, 1836)

Parasitology ◽  
1967 ◽  
Vol 57 (2) ◽  
pp. 251-261 ◽  
Author(s):  
W. E. Stehbens ◽  
M. R. L. Johnston
Keyword(s):  
Endoplasmic Reticulum ◽  
Technical Assistance ◽  
Red Cell ◽  
Unit Membrane ◽  
Cell Cytoplasm ◽  
Erythrocytic Stage ◽  
Membranous Structure ◽  
Conventional Unit ◽  
Gehyra Variegata

The ultrastructure of the intra-erythrocytic stage of a haemogregarine in the gecko, Gehyra variegata, has been studied and numerous points of similarity to Plasmodium, Toxoplasma, Sarcocystis, Lankesterella, Eimeria and the M-organism were found. The protozoon was invested by a triple-layered pellicle, and possessed at least two micropyles. A conoid and apical rings were observed at the anterior end. Other cell constituents included nucleus, microtubules, endoplasmic reticulum, mitochondria, toxonemes and a variety of vacuoles. Loosely surrounding the parasite was an unusual convoluted membrane, which in appropriate planes of section, displayed corrugations on both surfaces. It was not clear whether this membranous structure should be regarded as an integral part of the protozoon or as an external coat which could be discarded upon emergence from the host red cell. Within its external sheath, the parasite lay in a periparasitic vacuole which was limited by a conventional unit membrane from the host red cell cytoplasm. The parasite did not exhibit any evidence of pinocytosis or phagocytosis.Our sincere thanks are due to Dr E. H. Mercer, Professor J. D. Smyth and Dr M. J. Mackerras for advice. Miss N. Carroll gave technical assistance.

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