Low-Temperature Scanning Electron Microscopy of Fungi and Fungus-Plant Interactions

Read, Nick D.

doi:10.1007/978-3-642-75818-8_2

Cited by 32 publications

(25 citation statements)

References 25 publications

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“…8). They contained very thin strands of segregated zones that are generally considered to contain a biological matrix including solutes, organelles, macromolecular structures, and so on (Read, 1991). Because segregated zones arise during rapid freezing, structural information like the amount of water can be inferred: The more widely spaced the segregated zones, the higher the water content.…”

Section: Discussionmentioning

confidence: 99%

Electron microscopic study of novel threadlike structures on the surfaces of mammalian organs

Lee

Yoo

Ogay

et al. 2006

Microscopy Res & Technique

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The ultrastructures of novel threadlike structures (NTSs) and corpuscles on the surfaces of internal organs of rats were investigated using electron microscopy. The samples were studied in situ by using a stereomicroscope and were taken for further morphological analysis. Scanning electron microscope (SEM) images revealed a bundle structure of threadlike tissue, which was composed of several 10-micro m-thick subducts. The surfaces of the corpuscles were rather coarse and fenestrated. The corpuscles had cucumber-like shapes with an average length of about 2 mm and a thickness of about 400 micro m. Transmission electron microscope (TEM) images disclosed disordered collagen fibers, which formed the extracellular matrix of the threadlike tissue, and immune-function cells, like macrophages, mast cells, and eosinophils. Sinuses of various diameters, which were thought to be cross-sections of the lumens of the subducts, were observed in the TEM, cryo-SEM and focused-ion-beam SEM images. These SEM images were obtained for the first time to reveal the detailed structure of the NTSs that were only recently discovered.

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Section: Discussionmentioning

confidence: 99%

Electron microscopic study of novel threadlike structures on the surfaces of mammalian organs

Lee

Yoo

Ogay

et al. 2006

Microscopy Res & Technique

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“…Beyond the reach of a morphological method like CLSM or the histological work with hematoxylin and eosin staining, cryo-SEM enables one to interpret the presence of liquid in samples as well as cellular structures (Read, 1991). Soluble materials, organelles, and macromolecules are retained in segregation zones during freezing.…”

Section: Bonghan Ducts Within Lymphatic Vesselsmentioning

confidence: 99%

Novel threadlike structures (Bonghan ducts) inside lymphatic vessels of rabbits visualized with a Janus Green B staining method

Lee

Yoo

Baik

et al. 2005

The Anatomical Record Part B

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A staining method has been developed for in situ and in vivo observation of a threadlike tissue afloat inside the lymphatic vessels of rabbits without adherence to the vessel wall. The existence of this novel structure was not noticed previously because it is extremely difficult to detect it by microscopic inspection of lymphatic vessels. We have found a method that utilizes Janus Green B (JGB), which stained heavily the novel structure. The tissue was studied by confocal laser scanning microscopy (CLSM), light microscopy, and cryoscanning electron microscopy (cryo-SEM). The CLSM image obtained by acridine orange staining of the novel tissue revealed its characteristic nuclei distribution: rod-shaped nuclei of 10-20 microm length aligned in a broken-line/striped fashion. Hematoxylin and eosin staining revealed the threadlike structure passing through a lymphatic valve as histologically distinct from lymphatic vessels and valves. The cryo-SEM image showed the threadlike structure inside a collapsed lymphatic vessel. There were spherical globular structures observable inside sinuses in a rapidly frozen sample, which suggests liquid flowing through the longitudinal ductules in the threadlike structure. The specific staining of the JGB suggests that these threadlike structures inside lymphatic vessels have a high density of mitochondria in their cells and/or nerve-like properties, either of which may provide important clues to their physiological function.

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“…A review of the literature revealed that fusion between spore germlings is common, and over 20 species were found to produce structures similar to CATs (35,36). Köhler (24) first showed fusion between germlings of Neurospora spp.The initial aim of the present study was to analyze the morphogenetic process of fusion between conidia and conidial germlings of N. crassa by using confocal live-cell imaging (9, 16) and low-temperature scanning electron microscopy of frozen-hydrated samples (33,34). We found that the three types of conidia (macroconidia, microconidia, and arthroconidia) produced by N. crassa (40) form CATs that are morphologically distinct and different in behavior from germ tubes.…”

mentioning

confidence: 99%

“…The initial aim of the present study was to analyze the morphogenetic process of fusion between conidia and conidial germlings of N. crassa by using confocal live-cell imaging (9, 16) and low-temperature scanning electron microscopy of frozen-hydrated samples (33,34). We found that the three types of conidia (macroconidia, microconidia, and arthroconidia) produced by N. crassa (40) form CATs that are morphologically distinct and different in behavior from germ tubes.…”

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confidence: 99%

Cell Biology of Conidial Anastomosis Tubes in Neurospora crassa

Arlt²,

et al. 2005

Self Cite

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Although hyphal fusion has been well documented in mature colonies of filamentous fungi, it has been little studied during colony establishment. Here we show that specialized hyphae, called conidial anastomosis tubes (CATs), are produced by all types of conidia and by conidial germ tubes of Neurospora crassa. The CAT is shown to be a cellular element that is morphologically and physiologically distinct from a germ tube and under separate genetic control. In contrast to germ tubes, CATs are thinner, shorter, lack branches, exhibit determinate growth, and home toward each other. Evidence for an extracellular CAT inducer derived from conidia was obtained because CAT formation was reduced at low conidial concentrations. A cr-1 mutant lacking cyclic AMP (cAMP) produced CATs, indicating that the inducer is not cAMP. Evidence that the transduction of the CAT inducer signal involves a putative transmembrane protein (HAM-2) and the MAK-2 and NRC-1 proteins of a mitogen-activated protein kinase signaling pathway was obtained because ham-2, mak-2, and nrc-1 mutants lacked CATs. Optical tweezers were used in a novel experimental assay to micromanipulate whole conidia and germlings to analyze chemoattraction between CATs during homing. Strains of the same and opposite mating type were shown to home toward each other. The cr-1 mutant also underwent normal homing, indicating that cAMP is not the chemoattractant. ham-2, mak-2, and nrc-1 macroconidia did not attract CATs of the wild type. Fusion between CATs of opposite mating types was partially inhibited, providing evidence of non-self-recognition prior to fusion. Microtubules and nuclei passed through fused CATs.Hyphal fusion (anastomosis) is commonly undergone at two stages during the development of the vegetative colony of a filamentous fungus. It occurs initially between spores or spore germlings during the early stages of colony establishment and subsequently between hyphae located behind leading hyphae of the peripheral growth zone of the mycelium. Among other proposed roles, vegetative hyphal fusion is believed to facilitate communication and the transport of water and nutrients within the colony by producing a complex interconnected hyphal network (14).Neurospora crassa is proving to be an excellent model system in which to analyze vegetative hyphal fusion (12,14). Live-cell analysis of hyphal fusion in mature colonies of N. crassa demonstrated that specialized fusion hyphae exhibit positive tropisms by growing (homing) toward each other, and their close vicinity to other hyphae can induce the formation of further fusion hyphae (15). Different stages in the homing and fusion process were defined, and this has been summarized by Glass et al. (14). The nature of the diffusible chemoattractant molecules responsible for these tropisms is unknown (15). A number of mutants unable to undergo hyphal fusion have been isolated. Mutants disrupted in the mak-2 and nrc-1 genes encode a mitogen-activated protein (MAP) kinase and a MAP kinase kinase kinase, respectively. These prote...

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Low-Temperature Scanning Electron Microscopy of Fungi and Fungus-Plant Interactions

Cited by 32 publications

References 25 publications

Electron microscopic study of novel threadlike structures on the surfaces of mammalian organs

Electron microscopic study of novel threadlike structures on the surfaces of mammalian organs

Novel threadlike structures (Bonghan ducts) inside lymphatic vessels of rabbits visualized with a Janus Green B staining method

Cell Biology of Conidial Anastomosis Tubes in Neurospora crassa

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