Sporogonic development of Haemoproteus meleagridis (Haemosporina: Haemoproteidae) in Culicoides edeni (Diptera: Ceratopogonidae)

1991 ◽  
Vol 69 (7) ◽  
pp. 1880-1888 ◽  
Author(s):  
Carter T. Atkinson
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Outer Surface ◽  
Blood Meal ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Polar Ring ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Crystalloid Body

Mature oocysts of Haemoproteus meleagridis developed in specimens of Culicoides edeni within 3–6 days after the midges took a blood meal from an infected domestic turkey. Approximately 50 sporozoites budded from the surface of a single sporoblast body. Sporogonic development was similar to that of reptilian, avian, and mammalian haemoproteids that are transmitted by ceratopogonid and tabanid flies, but unlike that of hippoboscid-transmitted species in birds, which form large, slowly developing oocysts with multiple sporoblast bodies. Ultrastructural features of developing oocysts included nuclei with prominent nucleoli, mitochondria, and sandwich-like arrays of crystalloid particles and smooth endoplasmic reticulum (ER) that were present on the outer surface of developing lipid droplets during early stages of sporogony. During budding of sporozoites, crystalloid particles measuring 30–40 nm in diameter were associated with the inner membrane complex of the sporozoite pellicle, arranged in rows between subpellicular microtubules. Mature sporozoites contained an apical complex composed of a polar ring with two anterior apical rings, from two to eight elongate rhoptries, 22 evenly spaced subpellicular microtubules, and a small anterior crystalloid body. Morphological similarities between the ER–crystalloid arrays and the ER–microperoxisome arrays that have been described in cells actively engaged in lipid biosynthesis suggest that the crystalloid body contains enzymes important in lipid metabolism.

scholarly journals STUDIES ON MICROPEROXISOMES II. A CYTOCHEMICAL METHOD FOR LIGHT AND ELECTRON MICROSCOPY

1972 ◽  
Vol 20 (12) ◽  
pp. 1006-1023 ◽  
Author(s):  
ALEX B. NOVIKOFF ◽  
PHYLLIS M. NOVIKOFF ◽  
CLEVELAND DAVIS ◽  
NELSON QUINTANA
Keyword(s):  
Endoplasmic Reticulum ◽  
Guinea Pig ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Light And Electron Microscopy ◽  
Distal Tubule ◽  
Striking Difference ◽  
High Concentration ◽  
Electron Microscopic ◽  
Pig Kidney

A modification of the Novikoff-Goldfischer alkaline 3,3'-diaminobenzidine medium for visualizing peroxisomes is described. It makes possible light microscopic as well as electron microscopic studies of a recently described class of peroxisomes, the microperoxisomes. Potassium cyanide (5 x 10–3 M) is included in the medium to inhibit mitochondrial staining, the pH is 9.7 and there is a high concentration of H2O2 (0.05%). Two cell types have been chosen to illustrate the advantages of the new procedure for demonstrating the microperoxisomes: the absorptive cells in the human jejunum and the distal tubule cells in the guinea pig kidney. Suggestive relations of microperoxisomes and lipid are described in the human jejunum. The microperoxisomes are strategically located between smooth endoplasmic reticulum that radiates toward the organelles and contains lipid droplets and "central domains" of highly specialized endoplasmic reticulum which do not show the lipid droplets. The microperoxisomes are also present at the periphery of large lipid-like drops. In the guinea pig kidney tubule there is a striking difference between the thick limb of Henle and distal tubule. The distal tubule has a population of cells with large numbers of microperoxisomes readily visible by light microscopy; these cells are not present in the thick limb of Henle. Other differences between the two are also described.

scholarly journals A conserved family of proteins facilitates nascent lipid droplet budding from the ER

2015 ◽  
Vol 211 (2) ◽  
pp. 261-271 ◽  
Author(s):  
Vineet Choudhary ◽  
Namrata Ojha ◽  
Andy Golden ◽  
William A. Prinz
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Caenorhabditis Elegans ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
De Novo ◽  
Fat Storage ◽  
Higher Eukaryotes ◽  
Er Membrane

Lipid droplets (LDs) are found in all cells and play critical roles in lipid metabolism. De novo LD biogenesis occurs in the endoplasmic reticulum (ER) but is not well understood. We imaged early stages of LD biogenesis using electron microscopy and found that nascent LDs form lens-like structures that are in the ER membrane, raising the question of how these nascent LDs bud from the ER as they grow. We found that a conserved family of proteins, fat storage-inducing transmembrane (FIT) proteins, is required for proper budding of LDs from the ER. Elimination or reduction of FIT proteins in yeast and higher eukaryotes causes LDs to remain in the ER membrane. Deletion of the single FIT protein in Caenorhabditis elegans is lethal, suggesting that LD budding is an essential process in this organism. Our findings indicated that FIT proteins are necessary to promote budding of nascent LDs from the ER.

scholarly journals Targeted disruption of the aromatase P450 gene (Cyp19) in mice and their ovarian and uterine responses to 17beta-oestradiol

2001 ◽  
Vol 170 (1) ◽  
pp. 99-111 ◽  
Author(s):  
K Toda ◽  
K Takeda ◽  
T Okada ◽  
S Akira ◽  
T Saibara ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Corpus Luteum ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Ovarian Follicles ◽  
Interstitial Cells ◽  
Aromatase Activity ◽  
Tubular Structures ◽  
Wild Type ◽  
Targeted Disruption

Aromatase P450 (CYP19) is an enzyme catalysing the conversion of androgens into oestrogens. We generated mice lacking aromatase activity (ArKO) by targeted disruption of Cyp19 and report the characteristic features of the ArKO ovaries and uteri as revealed by histological and biochemical analyses. ArKO females were totally infertile but there were as many developing follicles in their ovaries at 8 weeks of age as in wild-type ovaries. Nevertheless, no typical corpus luteum was observed in the ArKO ovaries. Electron microscopy revealed the presence of well-developed smooth endoplasmic reticulum, few lipid droplets and mitochondria with less organized tubular structures in the ArKO luteinized interstitial cells. These ultrastructural features were different from those of the wild-type interstitial cells, where there are many lipid droplets and mitochondria with well-developed tubular structures, characteristic of steroid-producing cells. When ArKO mice were supplemented with 17beta-oestradiol (E(2); 15 microg/mouse) every fourth day from 4 weeks of age for 1 month, increased numbers of follicles were observed in the ovaries as compared with those of untreated ArKO mice, although no typical corpus luteum was detectable. Ultrastructural analysis revealed the disappearance of the accumulated smooth endoplasmic reticulum in the luteinized interstitial cells after E(2 )supplementation. Transcripts of pro-apoptotic genes such as p53 and Bax genes were markedly elevated in the ArKO ovaries as compared with those of wild-type mice. Although E(2) supplementation did not cause suppression of the elevated expression of p53 and Bax mRNAs, it caused marked enhancement of expression levels of lactoferrin and progesterone receptor mRNAs in the uteri as well as increases in uterine wet weight. At 8 months of age, ArKO mice developed haemorrhages in the ovaries, in which follicles were nearly depleted, while age-matched wild-type females still had many ovarian follicles. Furthermore, macrophage-like cells were occasionally observed in the ArKO ovarian follicles. These results suggested that targeted disruption of Cyp19 caused anovulation and precocious depletion of ovarian follicles. Additionally, analysis of mice supplemented with E(2) demonstrated that E(2) apparently supports development of ovarian follicles, although it did not restore the defect in ovulation.

scholarly journals Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus 

Contact ◽  
2020 ◽  
Vol 3 ◽  
pp. 251525642094582
Author(s):  
Veijo T. Salo ◽  
Maarit Hölttä-Vuori ◽  
Elina Ikonen
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Recent Work ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Intimate Relationship

Lipid droplets (LDs) are dynamic cellular hubs of lipid metabolism. While LDs contact a plethora of organelles, they have the most intimate relationship with the endoplasmic reticulum (ER). Indeed, LDs are initially assembled at specialized ER subdomains, and recent work has unraveled an increasing array of proteins regulating ER-LD contacts. Among these, seipin, a highly conserved lipodystrophy protein critical for LD growth and adipogenesis, deserves special attention. Here, we review recent insights into the role of seipin in LD biogenesis and as a regulator of ER-LD contacts. These studies have also highlighted the evolving concept of ER and LDs as a functional continuum for lipid partitioning and pinpointed a role for seipin at the ER-LD nexus in controlling lipid flux between these compartments.

scholarly journals A variant of the pyroantimonate technique suitable for localization of calcium in ovarian tissue.

1979 ◽  
Vol 27 (6) ◽  
pp. 1017-1028 ◽  
Author(s):  
B S Weakley
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Lipid Droplets ◽  
Microprobe Analysis ◽  
Smooth Endoplasmic Reticulum ◽  
Ovarian Tissue ◽  
Follicle Cells ◽  
Fixation Time ◽  
X Ray ◽  
Cytoplasmic Processes

Osmium-pyroantimonate solutions for the precipitation of cations are unsuitable for use with delicate mammalian oocytes. A variant of the pyroantimonate technique employing a mixture of pyroantimonate and glutaraldehyde has been found to give successful and repeatable results if a fixation time of 4 hr is used. Calcium-containing antimonate precipitates were localized principally in nuclei, smooth endoplasmic reticulum, Golgi apparatus, mitochondria, and cytoplasmic processes of both oocytes and follicle cells, and along the plasma membrane in small oocytes. Deposits were also concentrated around the periphery of lipid droplets in the follicle cells. The presence of calcium in the precipitates was confirmed by x-ray microprobe analysis.

scholarly journals Ultrastructural analysis of the dorsal body gland of the terrestrial snail Megalobulimus abbreviatus (Becquaert, 1948)

2010 ◽  
Vol 70 (2) ◽  
pp. 341-350 ◽  
Author(s):  
GD Moraes ◽  
M. Achaval ◽  
MM Dal Piva ◽  
MC Faccioni-Heuser ◽  
GF Wassermann ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Lipid Droplets ◽  
Neural Control ◽  
Smooth Endoplasmic Reticulum ◽  
Nerve Endings ◽  
Retrograde Labelling ◽  
Axon Terminals ◽  
Cerebral Ganglia ◽  
Reproductive Gland

The ultrastructure of the reproductive gland, dorsal body (DB), of Megalobulimus abbreviatus was analysed. Electron microscope immunohistochemistry was used to detect FMRFamide-like peptides in the nerve endings within this gland. Nerve backfilling was used in an attempt to identify the neurons involved in this innervation. In M. abbreviatus, the DB has a uniform appearance throughout their supraesophageal and subesophageal portions. Dorsal body cells have several features in common with steroid-secreting gland cells, such as the presence of many lipid droplets, numerous mitochondria with tubular cristae and a developed smooth endoplasmic reticulum cisternae. Throughout the DB in M. abbreviatus numerous axonal endings were seen to be in contact with the DB cells exhibiting a synaptic-like structure. The axon terminals contained numerous electron-dense and scanty electron-lucid vesicles. In addition, the DB nerve endings exhibited FMRFamide immunoreactive vesicles. Injection of neural tracer into the DB yielded retrograde labelling of neurons in the metacerebrum lobe of the cerebral ganglia and in the parietal ganglia of the subesophageal ganglia complex. The possibility that some of these retrograde-labelled neurons might be FMRFamide-like neurons that may represent a neural control to the DB in M. abbreviatus is discussed.

Histopathologic and Ultrastructural Alterations of White Liver Disease in Sheep Experimentally Depleted of Cobalt

1997 ◽  
Vol 34 (6) ◽  
pp. 575-584 ◽  
Author(s):  
S. Kennedy ◽  
S. McConnell ◽  
H. Anderson ◽  
D. G. Kennedy ◽  
P. B. Young ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Body Weight ◽  
Liver Disease ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Plasma Concentrations ◽  
Fatty Degeneration ◽  
Vitamin B ◽  
Liver Lesions ◽  
Lipofuscin Granules

Many cobalt-deficient sheep develop liver lesions known as ovine "white liver" disease, but the etiology of these changes is controversial. It has been suggested that cofactors are required for development of liver damage in cobalt-deficient sheep. In this study, one group of lambs ( n=5) was fed a diet low in cobalt (4.5 μg/kg) while a group of control lambs ( n=4) received the same diet after it had been supplemented with cobalt (1000 μg/kg). All cobalt-depleted lambs had reduced growth rate, anorexia, lacrimation, and alopecia, and they eventually became emaciated (mean body weight at end of study: 83% of initial body weight). Plasma concentrations of bilirubin and serum activity of glutamate-oxaloacetate transferase were elevated in these animals, while plasma concentrations of vitamin B12 were reduced (less than 220 pmol/L from day 42). Fatty degeneration of the liver associated with reduced concentrations of vitamin B12 (14.5 pmol/g) was seen in these animals at necropsy at 196 days. Microscopic liver lesions included accumulation of lipid droplets and lipofuscin particles in hepatocytes, dissociation and necrosis of hepatocytes, and sparse infiltration by neutrophils, macrophages, and lymphocytes. Ultrastructural hepatocytic alterations included swelling, condensation and proliferation of mitochondria, hypertrophy of smooth endoplasmic reticulum, vesiculation and loss of arrays of rough endoplasmic reticulum, and accumulation of lipid droplets and lipofuscin granules in cytoplasm of hepatocytes. No liver lesions were seen in control lambs. The results of this study indicate that cofactors are not a prerequisite to development of hepatic damage in cobalt-deficient sheep. Reduced activities of the vitamin B12-dependent enzymes, methylmalonyl CoA mutase and methionine synthase, and lipid peroxidation are of likely pathogenetic importance in the development of the lesions.

Ultrastructural characterization of in vivo-produced ovine morulae and blastocysts

Zygote ◽  
2014 ◽  
Vol 23 (4) ◽  
pp. 583-593 ◽  
Author(s):  
E.M.V. Bettencourt ◽  
C.M.V. Bettencourt ◽  
J.N. Chagas e Silva ◽  
P. Ferreira ◽  
E. Oliveira ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Intercellular Junctions ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Secretory Vesicles ◽  
Embryonic Cells ◽  
Trophectoderm Cells

SummaryThe ultrastructure of in vivo-produced ovine embryos, at the morula, early blastocyst and late blastocyst stages, was evaluated using transmission electron microscopy. Embryonic cells were characterized by the presence of intact intercellular junctions, numerous mitochondria, smooth endoplasmic reticulum cisternae and light vesicles. Polyribosomes, rough endoplasmic reticulum cisternae, secondary lysosomes, Golgi complexes and lipid droplets were also observed in the cytoplasm. The nucleus was well defined and organized, with an intact envelope rich in nuclear pore complexes, and one or more reticular nucleoli. Microvilli were present in external blastomeres of morulae and became more abundant in trophectoderm cells of early and late blastocysts. Light vesicles seemed to be associated with small cisternae of Golgi and endoplasmic reticulum origin. These cisternae fused and created light vesicles with engulfed heterogeneous cytosolic structures, small cisternae and vesicles. Their labile membrane enabled them to rapidly coalesce into medium-sized vesicles that began to engulf mitochondria and lipid droplets, forming giant vacuoles mostly filled with fat. Incomplete matured secretory vesicles were observed to exocytose into the perivitelline space of morulae, whereas fully matured secretory vesicles appeared only in trophectoderm cells, being exocytosed into the blastocoelic cavity. These observations suggested that these endoplasmic-/Golgi-derived vesicles behave as active autophagic organelles presenting probably a maturation process from compact morulae to blastocyst.

scholarly journals Yeast Cells Exposed to Exogenous Palmitoleic Acid Either Adapt to Stress and Survive or Commit to Regulated Liponecrosis and Die

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Karamat Mohammad ◽  
Paméla Dakik ◽  
Younes Medkour ◽  
Mélissa McAuley ◽  
Darya Mitrofanova ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Lipid Metabolism ◽  
Lipid Droplets ◽  
Palmitoleic Acid ◽  
Molecular Mechanisms ◽  
Neutral Lipids ◽  
Yeast Cells ◽  
Cellular Processes ◽  
Regulated Cell Death

A disturbed homeostasis of cellular lipids and the resulting lipotoxicity are considered to be key contributors to many human pathologies, including obesity, metabolic syndrome, type 2 diabetes, cardiovascular diseases, and cancer. The yeast Saccharomyces cerevisiae has been successfully used for uncovering molecular mechanisms through which impaired lipid metabolism causes lipotoxicity and elicits different forms of regulated cell death. Here, we discuss mechanisms of the “liponecrotic” mode of regulated cell death in S. cerevisiae. This mode of regulated cell death can be initiated in response to a brief treatment of yeast with exogenous palmitoleic acid. Such treatment prompts the incorporation of exogenously added palmitoleic acid into phospholipids and neutral lipids. This orchestrates a global remodeling of lipid metabolism and transfer in the endoplasmic reticulum, mitochondria, lipid droplets, and the plasma membrane. Certain features of such remodeling play essential roles either in committing yeast to liponecrosis or in executing this mode of regulated cell death. We also outline four processes through which yeast cells actively resist liponecrosis by adapting to the cellular stress imposed by palmitoleic acid and maintaining viability. These prosurvival cellular processes are confined in the endoplasmic reticulum, lipid droplets, peroxisomes, autophagosomes, vacuoles, and the cytosol.

scholarly journals Getting a handle on lipid droplets: Insights into ER–lipid droplet tethering

2019 ◽  
Vol 218 (4) ◽  
pp. 1089-1091 ◽  
Author(s):  
Truc B. Nguyen ◽  
James A. Olzmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Human Cells ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Cell Biol ◽  
Membrane Contact

Lipid droplets (LDs) are hubs for lipid metabolism that form membrane contact sites with multiple organelles. In this issue, Hariri et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201808119) reveal the functions of Mdm1-mediated endoplasmic reticulum (ER)–LD tethering in yeast and Datta et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201808133) identify a role for the Mdm1 orthologue, Snx14, as an ER–LD tether that regulates lipid metabolism in human cells.

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