scholarly journals The Dictyostelium discoideum GPHR Ortholog Is an Endoplasmic Reticulum and Golgi Protein with Roles during Development

2014 ◽  
Vol 14 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Jaqueline Deckstein ◽  
Jennifer van Appeldorn ◽  
Marios Tsangarides ◽  
Kyriacos Yiannakou ◽  
Rolf Müller ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Dictyostelium Discoideum ◽  
Developmental Stages ◽  
Transmembrane Protein ◽  
Anion Channel ◽  
Developmentally Regulated ◽  
Content Type ◽  
In The Wild ◽  
G Protein Coupled

ABSTRACT Dictyostelium discoideum GPHR ( G olgi pH r egulator)/Gpr89 is a developmentally regulated transmembrane protein present on the endoplasmic reticulum (ER) and the Golgi apparatus. Transcript levels are low during growth and vary during development, reaching high levels during the aggregation and late developmental stages. The Arabidopsis ortholog was described as a G protein-coupled receptor (GPCR) for abscisic acid present at the plasma membrane, whereas the mammalian ortholog is a Golgi apparatus-associated anion channel functioning as a Golgi apparatus pH regulator. To probe its role in D. discoideum , we generated a strain lacking GPHR. The mutant had different growth characteristics than the AX2 parent strain, exhibited changes during late development, and formed abnormally shaped small slugs and fruiting bodies. An analysis of development-specific markers revealed that their expression was disturbed. The distributions of the endoplasmic reticulum and the Golgi apparatus were unaltered at the immunofluorescence level. Likewise, their functions did not appear to be impaired, since membrane proteins were properly processed and glycosylated. Also, changes in the external pH were sensed by the ER, as indicated by a pH-sensitive ER probe, as in the wild type.

scholarly journals Rates of synthesis and degradation of ribosomal ribonucleic acid during differentiation of Dictyostelium discoideum.

1981 ◽  
Vol 1 (1) ◽  
pp. 35-42 ◽  
Author(s):  
G Mangiarotti ◽  
F Altruda ◽  
H F Lodish
Keyword(s):  
Dictyostelium Discoideum ◽  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Developmental Stages ◽  
Growth Conditions ◽  
Developmentally Regulated ◽  
Rna Translation ◽  
Ribosomal Ribonucleic Acid ◽  
Messenger Rna Translation ◽  
Synthesis And Degradation

Synthesis of ribosomes and ribosomal ribonucleic acid (RNA) continued during differentiation of Dictyostelium discoideum concurrently with extensive turnover of ribosomes synthesized during both growth and developmental stages. We show here that the rate of synthesis of 26S and 17S ribosomal RNA during differentiation was less than 15% of that in growing cells, and by the time of sorocarp formation only about 25% of the cellular ribosomes had been synthesized during differentiation. Ribosomes synthesized during growth and differentiation were utilized in messenger RNA translation to the same extent; about 50% of each class were on polyribosomes. Ribosome degradation is apparently an all-or-nothing process, since virtually all 80S monosomes present in developing cells could be incorporated into polysomes when growth conditions were restored. By several criteria, ribosomes synthesized during growth and differentiation were functionally indistinguishable. Our data, together with previously published information on changes in the messenger RNA population during differentiation, indicate that synthesis of new ribosomes is not necessary for translation of developmentally regulated messenger RNA. We also establish that the overall rate of messenger RNA synthesis during differentiation is less than 15% of that in growing cells.

scholarly journals Electron Microscopy of the Development of Tracheoles in Drosophila Melanogaster

1963 ◽  
Vol s3-104 (65) ◽  
pp. 135-140
Author(s):  
S. AHMAD SHAFIQ
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Drosophila Melanogaster ◽  
Golgi Apparatus ◽  
Plasma Membranes ◽  
Developmental Stages ◽  
Membrane Structures ◽  
Flight Muscles

The tracheoblasts associated with the flight-muscles of Drosophila were studied by electron microscopy. During the developmental stages the cytoplasm of such tracheoblasts shows extensive membrane structures arranged in whorls. It seems that these membranes become aligned in pairs, spread out in tracheoblast cytoplasm, and form the walls of the new tracheolar vessels. The membranous whorls appear to have no obvious relationship with the usual endoplasmic reticulum, Golgi apparatus or plasma membranes. They are probably produced from certain large granules distributed irregularly in the cytoplasm of the young tracheoblasts. Membranes limiting the tracheoles from the tracheoblast cytoplasm (the so-called mestracheons) are not usually seen in the younger stages. They are sometimes seen after the cuticular lining of the tracheoles has been formed.

Rates of synthesis and degradation of ribosomal ribonucleic acid during differentiation of Dictyostelium discoideum

1981 ◽  
Vol 1 (1) ◽  
pp. 35-42
Author(s):  
G Mangiarotti ◽  
F Altruda ◽  
H F Lodish
Keyword(s):  
Dictyostelium Discoideum ◽  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Developmental Stages ◽  
Growth Conditions ◽  
Developmentally Regulated ◽  
Rna Translation ◽  
Ribosomal Ribonucleic Acid ◽  
Messenger Rna Translation ◽  
Synthesis And Degradation

Synthesis of ribosomes and ribosomal ribonucleic acid (RNA) continued during differentiation of Dictyostelium discoideum concurrently with extensive turnover of ribosomes synthesized during both growth and developmental stages. We show here that the rate of synthesis of 26S and 17S ribosomal RNA during differentiation was less than 15% of that in growing cells, and by the time of sorocarp formation only about 25% of the cellular ribosomes had been synthesized during differentiation. Ribosomes synthesized during growth and differentiation were utilized in messenger RNA translation to the same extent; about 50% of each class were on polyribosomes. Ribosome degradation is apparently an all-or-nothing process, since virtually all 80S monosomes present in developing cells could be incorporated into polysomes when growth conditions were restored. By several criteria, ribosomes synthesized during growth and differentiation were functionally indistinguishable. Our data, together with previously published information on changes in the messenger RNA population during differentiation, indicate that synthesis of new ribosomes is not necessary for translation of developmentally regulated messenger RNA. We also establish that the overall rate of messenger RNA synthesis during differentiation is less than 15% of that in growing cells.

Golgi Apparatus and Melanogenesis: Ultrastructural Study of a Human Cellular Blue Nevus (Melanocytoma)

1973 ◽  
Vol 31 ◽  
pp. 380-381
Author(s):  
S.R. Allegra
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Ultrastructural Study ◽  
The Other ◽  
Blue Nevus ◽  
Normal Complement ◽  
Golgi Vesicles ◽  
Golgi System ◽  
The Subject ◽  
Cellular Blue Nevus

The respective roles of the ribo somes, endoplasmic reticulum, Golgi apparatus and perhaps nucleus in the synthesis and maturation of melanosomes is still the subject of some controversy. While the early melanosomes (premelanosomes) have been frequently demonstrated to originate as Golgi vesicles, it is undeniable that these structures can be formed in cells in which Golgi system is not found. This report was prompted by the findings in an essentially amelanotic human cellular blue nevus (melanocytoma) of two distinct lines of melanocytes one of which was devoid of any trace of Golgi apparatus while the other had normal complement of this organelle.

Spermatogenesis in the Dragonfly with Particular Reference to the Cytoplasmic Organelles

1972 ◽  
Vol 30 ◽  
pp. 110-111
Author(s):  
Sant S. Sekhon
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Mature Sperm ◽  
Electron Microscopic ◽  
Cytoplasmic Organelles ◽  
Microscopic Studies ◽  
Insect Sperm ◽  
Large Round

Although there have been numerous studies concerning the morphogenetic changes accompanying the maturation of insect sperm, only a few deal with the sperm differentiation in the dragonflies. In two recent electron microscopic studies Kessel, has comprehensively treated the erlationship of microtubules to the nucleus and mid-piece structures during spermiogenesis in the dragonfly. The purpose of this study is to follow the sequential nuclear and cytoplasmic changes which accompany the differentiation of spermatogonium into a mature sperm during spermatogenesis in the dragonfly (Aeschna sp.).The dragonfly spermatogonia are characterized by large round nuclei. Loosely organized chromatin is usually unevenly distributed within the spermatogonial nuclei. The scant cytoplasm surrounding the nucleus contains mitochondria, the Golgi apparatus, elements of endoplasmic reticulum and numerous ribosomes (Fig. 1).

An Ultra-Structural Study of Human Melanoma in Vivo and Vitro

1976 ◽  
Vol 34 ◽  
pp. 258-259
Author(s):  
James R. Gaylor ◽  
Fredda Schafer ◽  
Robert E. Nordquist
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Protein Aggregation ◽  
Structural Study ◽  
Human Melanoma ◽  
Protein Matrix ◽  
Early Form ◽  
Endoplasmic Reticulum Protein ◽  
Mitochondrial Origin

Several theories on the origin of the melanosome exist. These include the Golgi origin theory, in which a tyrosinase-rich protein is "packaged" by the Golgi apparatus, thus forming the early form of the melanosome. A second theory postulates a mitochondrial origin of melanosomes. Its author contends that the melanosome is a modified mitochondria which acquires melanin during its development. A third theory states that a pre-melanosome is formed in the smooth or rough endoplasmic reticulum. Protein aggregation is suggested by one author as a possible source of the melanosome. This fourth theory postulates that the melanosome originates when the protein products of several genetic loci aggregate in the cytoplasm of the melanocyte. It is this protein matrix on which the melanin is deposited. It was with these theories in mind that this project was undertaken.

scholarly journals Hepatic endosome fractions contain an ATP-driven proton pump

1985 ◽  
Vol 225 (1) ◽  
pp. 51-58 ◽  
Author(s):  
T Saermark ◽  
N Flint ◽  
W H Evans
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Atpase Activity ◽  
Proton Pump ◽  
Subcellular Distribution ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Ph Gradients ◽  
Subcellular Organelle ◽  
Liver Homogenates

Endosome fractions were isolated from rat liver homogenates on the basis of the subcellular distribution of circulating ligands, e.g. 125I-asialotransferrin internalized by hepatocytes by a receptor-mediated process. The distribution of endocytosed 125I-asialotransferrin 1-2 min and 15 min after uptake by liver and a monensin-activated Mg2+-dependent ATPase activity coincided on linear gradients of sucrose and Nycodenz. The monensin-activated Mg2+-ATPase was enriched relative to the liver homogenates up to 60-fold in specific activity in the endosome fractions. Contamination of the endosome fractions by lysosomes, endoplasmic reticulum, mitochondria, plasma membranes and Golgi-apparatus components was low. By use of 9-aminoacridine, a probe for pH gradients, the endosome vesicles were shown to acidify on addition of ATP. Acidification was reversed by addition of monensin. The results indicate that endosome fractions contain an ATP-driven proton pump. The ionophore-activated Mg2+-ATPase in combination with the presence of undegraded ligands in the endosome fractions emerge as linked markers for this new subcellular organelle.

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