Light and electron microscope studies on the conidium and germ tube of Sphaerotheca macularis

1970 ◽  
Vol 16 (5) ◽  
pp. 273-280 ◽  
Author(s):  
N. L. Mitchell ◽  
W. E. McKeen
Keyword(s):  
Endoplasmic Reticulum ◽  
Germ Tube ◽  
Vacuolar Membrane ◽  
Serial Sections ◽  
Dense Granules ◽  
Leading Position ◽  
Membrane Bound ◽  
Sphaerotheca Macularis ◽  
Glycogen Particles ◽  
Germ Tubes

Measurements made from electron micrographs of serial sections and from thoroughly plasmolyzed conidia indicate that more than 50% of the volume of the conidia of Sphaerotheca macularis consists of vacuoles in which most of the water in the conidia is stored. Electron-dense granules inside the vacuoles evidently include storage materials. Some developing vacuoles, particularly those of the germ tube, enclose membrane-bound bodies resembling lysosomes which later disappear as the vacuoles enlarge. Conspicuous multimembraned myelin-like bodies project inside the vacuolar cavity, their membranes being continuous with the vacuolar membrane. These bodies are believed to function in the synthesis of new cytoplasmic materials from the reserves in the vacuoles.The conidium, which may later produce up to four germ tubes, always retains a nucleus. The nucleus contains a peripheral granule which maintains a leading position on migrating nuclei and divides into two during the initial stages of nuclear division.Germ tubes respond positively to the stimulus of unilateral illumination and are produced on the illuminated sides of the conidia. Cytoplasmic changes which accompany germination include the increase in number and size of mitochondria, particularly in the germ tube. Their multiplication appears to be by fission. Endoplasmic reticulum is greatly increased and ribosomes are more abundant. Aggregated granules resembling glycogen particles also occur, these not being usually seen in resting conidia.

The ultrastructure of the double membrane-bound bodies and endoplasmic reticulum in serial sections of wheat spot mosaic-affected wheat plants

1990 ◽  
Vol 48 (3) ◽  
pp. 694-695
Author(s):  
M. H. Chen ◽  
C. Hiruki
Keyword(s):  
Endoplasmic Reticulum ◽  
High Resolution ◽  
Membrane Structure ◽  
Mosaic Disease ◽  
Serial Sections ◽  
Thin Sections ◽  
Double Membrane ◽  
Southern Alberta ◽  
Membrane Bound ◽  
Scanning Em

Wheat spot mosaic disease was first discovered in southern Alberta, Canada, in 1956. A hitherto unidentified disease-causing agent, transmitted by the eriophyid mite, caused chlorosis, stunting and finally severe necrosis resulting in the death of the affected plants. Double membrane-bound bodies (DMBB), 0.1-0.2 μm in diameter were found to be associated with the disease.Young tissues of leaf and root from 4-wk-old infected wheat plants were fixed, dehydrated, and embedded in Spurr’s resin. Serial sections were collected on slot copper grids and stained. The thin sections were then examined with a Hitachi H-7000 TEM at 75 kV. The membrane structure of the DMBBs was studied by numbering them individually and tracing along the sections to see any physical connection with endoplasmic reticulum (ER) membranes. For high resolution scanning EM, a modification of Tanaka’s method was used. The specimens were examined with a Hitachi Model S-570 SEM in its high resolution mode at 20 kV.

Evidence for Golgi Origin of Melanosomes

1968 ◽  
Vol 26 ◽  
pp. 148-149
Author(s):  
Gerd G. Maul
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Golgi Complex ◽  
Serial Sections ◽  
Human Malignant Melanoma ◽  
Close Proximity ◽  
Membrane Bound ◽  
Tubular Endoplasmic Reticulum ◽  
Internal Architecture

Electron microscopy has provided evidence that the melanosome evolves as a membrane bound structure with a highly complex internal architecture. The premelanosomes are found in close proximity to the golgi apparatus. Therefore, it was generally agreed that the melanosomes originate from the golgi apparatus.Vesicles have been described to pinch off the cysternae of the golgi apparatus. The vesicles would then grow and acquire a dense material. This material is aggregating to form the characteristic helical strands onto which melanin is deposited. Cloned human malignant melanoma lines were used to reinvestigate the problem of melanosome formation. The reconstruction of serial sections revealed the arrangement of premelanosomes and melanosomes in relation to the golgi complex. This study demonstrated that premelanosomes and melanosomes are continuous with the golgi complex by a smooth-surfaced tubular endoplasmic reticulum (SER) (Fig. la-d). The continuity of membranes of the SER and the premelanosome is depicted in Fig. 2. In this early premelanosome the protein strands have not yet coiled up into a helix. Rough-surfaced endoplasmic reticulum (RER) was also observed to be continuous with the golgi apparatus and melanosomes. After melanogenesis has started (Fig. 3) small vesicles appear inside the premelanosomes.

Ultrastructure of basidiospore germination in Fomes fomentarius

1978 ◽  
Vol 56 (22) ◽  
pp. 2865-2872 ◽  
Author(s):  
Ichiko Tsuneda ◽  
Lorene L. Kennedy
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Germ Tube ◽  
Early Stage ◽  
Dense Layer ◽  
Lipid Bodies ◽  
Fomes Fomentarius ◽  
Additional Cell ◽  
Thin Electron ◽  
Germ Tubes

Germination of basidiospores in Fomes fomentarius (Fries) Kickx is bipolar with germ tubes emerging at both ends. Ungerminated spores are smooth with a thick cell wall consisting of two layers: an outer thin, electron-dense layer and an inner thick, electron-light layer. During the early stage of germination, two additional cell wall layers are formed: a very thin, electron-dense layer and a relatively thick, electron-light layer. Germ tube walls originate from these newly formed, inner layers. Ungerminated spores are uninucleate and contain numerous lipid bodies, ribosomes, and cisternae of endoplasmic reticulum. Germinated spores have distinct mitochondria and an invaginated plasma membrane and are usually devoid of endoplasmic reticulum.

Ultrastructure and lipid identification during conidium germination of Stemphylium sarcinaeforme

1976 ◽  
Vol 22 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Gordon M. Murray ◽  
Douglas P. Maxwell
Keyword(s):  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Total Lipid ◽  
Germ Tube ◽  
Tube Wall ◽  
Dry Weight ◽  
Lipid Bodies ◽  
Conidium Germination ◽  
Germ Tubes ◽  
Qualitative Changes

Multicelled conidia of Stemphylium sarcinaeforme germinate in water forming several germ tubes. Individual cells within conidia are connected by pores which are plugged in ungerminated conidia and open in germinated ones. During germination, vacuoles enlarge, endoplasmic reticulum profiles increase in number, and mitochondria change from spherical to elongate. The germ tube wall is laid down at the site of emergence from the conidium. Shortly after germination, a septum with a central pore forms where the germ tube emerged. The germ tube wall is surrounded by a fibrillar sheath. Lipid bodies are closely associated with vacuoles during germination. The ultrastructural location of lipid was found by extraction of conidia with lipid solvents. Total lipid decreases from 14.4% of the dry weight of ungerminated conidia to 13.4% of the dry weight of conidia germinated for 10 h. No qualitative changes occurred in the major lipid classes of conidia during germination. The activities of lipase and acid phosphatase were detected in ungerminated and germinated conidia.

The Biology of Fungi

2019 ◽  
Author(s):  
Stephanie J. Smith ◽  
Rohini J. Manuel
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Germ Tube ◽  
Fungal Species ◽  
Molecular Techniques ◽  
Fungal Cell ◽  
Tube Test ◽  
Membrane Bound ◽  
Filamentous Material ◽  
One Fungus One Name

Fungi are found ubiquitously in the environment such as soil, water, and food. There are an estimated 1.5 million fungal species worldwide, although this number is felt to be grossly underestimated and is regularly updated. Of these vast numbers, around 500 fungi to date have been implicated in human disease. As opposed to bacteria, which are prokaryotes, fungi are eukaryotes, meaning they have a well-defined nucleus and have membrane- bound organelles in the cytoplasm, including an endoplasmic reticulum and a golgi apparatus. In 1969, the scientist R. H. Whittaker first proposed that organisms be classified into five kingdoms: Monera (Bacteria), Protista (Algae and Protozoans), Plantae (Plants), Mycetae (Fungi), and Animalia (Animals). Since then, there have been dramatic changes to the classifications of fungi, largely due to the appliance of phylogenetic molecular techniques. This has resulted in variances to the number of phylums, and the species assigned to them. Table 3.1 shows the seven phyla of the Fungi Kingdom. The majority of fungi pathogenic to humans inhabit the Ascomycota and Basidiomycota phyla. Fungi used to be dually named if they had a pleomorphic life cycle with sexual/ asexual stages (teleomorph/ anamorph, respectively), which meant that fungi often had two names and were classed differently. This practice was discontinued in January 2013 after the International Commission on the Taxonomy of Fungi decided that a ‘one fungus, one name’ approach should be followed. Fungi can be unicellular (yeast) or multicellular (fungi). Yeasts may look globose in nature when grown, whereas multicellular fungi grow as tubular, filamentous material called hyphae that can create a branching, hyphal network called a mycelium. Hyphae may have septa that cross their walls or be nonseptate, which is a method of differentiating fungi. An early hyphal outgrowth from a spore is called a germ tube. The germ tube test can be used to differentiate the yeasts Candida albicans and Candida dubliniensis from other Candida species. The fungal cell wall is composed of chitin and glucans, which are different components to the human cell wall. This means that they can be an effective target for antifungal therapy.

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

Temporal and spatial interrelationships of confronting cisternae to nuclear envelope

1992 ◽  
Vol 50 (1) ◽  
pp. 930-931
Author(s):  
John R. Palisano
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Tumor Cells ◽  
Hela Cells ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Serial Sections ◽  
Electron Microscopic ◽  
Fetal Rat ◽  
Temporal And Spatial

Although confronting cistemae (CC) have been observed in a variety of tumor cells and normal fetal rat, mouse, and human epithelial tissues, little is known about their origin or role in mitotic cells. While several investigators have suggested that CC arise from nuclear envelope (NE) folding back on itself during prophase, others have suggested that CC arise when fragments of NE pair with endoplasmic reticulum. An electron microscopic investigation of 0.25 um thick serial sections was undertaken to examine the origin of CC in HeLa cells.

scholarly journals Craniofacial Diseases Caused by Defects in Intracellular Trafficking

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 726
Author(s):  
Chung-Ling Lu ◽  
Jinoh Kim
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Intracellular Trafficking ◽  
Critical Role ◽  
Treatment Strategies ◽  
Soluble Proteins ◽  
Genes Encoding ◽  
Membrane Bound ◽  
Signaling Receptors ◽  
Craniofacial Morphogenesis

Cells use membrane-bound carriers to transport cargo molecules like membrane proteins and soluble proteins, to their destinations. Many signaling receptors and ligands are synthesized in the endoplasmic reticulum and are transported to their destinations through intracellular trafficking pathways. Some of the signaling molecules play a critical role in craniofacial morphogenesis. Not surprisingly, variants in the genes encoding intracellular trafficking machinery can cause craniofacial diseases. Despite the fundamental importance of the trafficking pathways in craniofacial morphogenesis, relatively less emphasis is placed on this topic, thus far. Here, we describe craniofacial diseases caused by lesions in the intracellular trafficking machinery and possible treatment strategies for such diseases.

scholarly journals Widespread occurrence of microRNA-mediated target cleavage on membrane-bound polysomes

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xiaoyu Yang ◽  
Chenjiang You ◽  
Xufeng Wang ◽  
Lei Gao ◽  
Beixin Mo ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Gene Silencing ◽  
High Frequency ◽  
Small Rnas ◽  
High Throughput Sequencing ◽  
Noncoding Rnas ◽  
Small Interfering Rnas ◽  
Widespread Occurrence ◽  
Membrane Bound ◽  
Different Tissues

Abstract Background Small RNAs (sRNAs) including microRNAs (miRNAs) and small interfering RNAs (siRNAs) serve as core players in gene silencing at transcriptional and post-transcriptional levels in plants, but their subcellular localization has not yet been well studied, thus limiting our mechanistic understanding of sRNA action. Results We investigate the cytoplasmic partitioning of sRNAs and their targets globally in maize (Zea mays, inbred line “B73”) and rice (Oryza sativa, cv. “Nipponbare”) by high-throughput sequencing of polysome-associated sRNAs and 3′ cleavage fragments, and find that both miRNAs and a subset of 21-nucleotide (nt)/22-nt siRNAs are enriched on membrane-bound polysomes (MBPs) relative to total polysomes (TPs) across different tissues. Most of the siRNAs are generated from transposable elements (TEs), and retrotransposons positively contributed to MBP overaccumulation of 22-nt TE-derived siRNAs (TE-siRNAs) as opposed to DNA transposons. Widespread occurrence of miRNA-mediated target cleavage is observed on MBPs, and a large proportion of these cleavage events are MBP-unique. Reproductive 21PHAS (21-nt phasiRNA-generating) and 24PHAS (24-nt phasiRNA-generating) precursors, which were commonly considered as noncoding RNAs, are bound by polysomes, and high-frequency cleavage of 21PHAS precursors by miR2118 and 24PHAS precursors by miR2275 is further detected on MBPs. Reproductive 21-nt phasiRNAs are enriched on MBPs as opposed to TPs, whereas 24-nt phasiRNAs are nearly completely devoid of polysome occupancy. Conclusions MBP overaccumulation is a conserved pattern for cytoplasmic partitioning of sRNAs, and endoplasmic reticulum (ER)-bound ribosomes function as an independent regulatory layer for miRNA-induced gene silencing and reproductive phasiRNA biosynthesis in maize and rice.

Vacuole Partitioning During Meiotic Division in Yeast

Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 445-458 ◽  
Author(s):  
Amy D Roeder ◽  
Janet M Shaw
Keyword(s):  
Alkaline Phosphatase ◽  
Meiotic Division ◽  
Cell Walls ◽  
Vacuolar Membrane ◽  
Carboxypeptidase Y ◽  
Fluorescent Markers ◽  
Immunofluorescence Studies ◽  
Membrane Bound ◽  
Subsequent Staining ◽  
Spore Cell

Abstract We have examined the partitioning of the yeast vacuole during meiotic division. In pulse-chase experiments, vacuoles labeled with the lumenal ade2 fluorophore or the membrane-specific dye FM 4-64 were not inherited by haploid spores. Instead, these fluorescent markers were excluded from spores and trapped between the spore cell walls and the ascus. Serial optical sections using a confocal microscope confirmed that spores did not inherit detectable amounts of fluorescently labeled vacuoles. Moreover, indirect immunofluorescence studies established that an endogenous vacuolar membrane protein, alkaline phosphatase, and a soluable vacuolar protease, carboxypeptidase Y, were also detected outside spores after meiotic division. Spores that did not inherit ade2- or FM 4-64-labeled vacuoles did generate an organelle that could be visualized by subsequent staining with vacuole-specific fluorophores. These data contrast with genetic evidence that a soluble vacuolar protease is inherited by spores. When the partitioning of both types of markers was examined in sporulating cultures, the vacuolar protease activity was inherited by spores while fluorescently labeled vacuoles were largely excluded from spores. Our results indicate that the majority of the diploid vacuole, both soluble contents and membrane-bound components, are excluded from spores formed during meiotic division.

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