Electron microscopic studies on the interaction between Lactobacillus phage PL-1 and cell walls isolated from its host cells.

An electron microscopic study was performed on haustoria of Phytophthora cactorum (L. et C.) Schroeter developed in tissues of two cultivars of apple fruits: a susceptible variety ('Golden delicious') and a resistant one ('Belle de Boskoop'). Ultrastructure of intercellular hyphae and some aspects of their penetration between contiguous host cells were described. A light dissolution of the host cell walls was observed. Ontogenic investigations indicated that in the susceptible host, the wall of the fungal haustoria was covered with a dense-stained extrahaustorial matrix. Its origin and its polysaccharide nature were demonstrated. On the other hand, the resistant host developed, immediately after the inoculation, a papilla which gave rise, later on, to a sheath enclosing adult haustoria. The role of these callosic structures in the phenomenon of resistance was discussed.

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Structure and host–actinomycete interactions in developing root nodules of Comptonia peregrina

Canadian Journal of Botany ◽

10.1139/b78-060 ◽

1978 ◽

Vol 56 (5) ◽

pp. 502-531 ◽

Cited By ~ 26

Author(s):

William Newcomb ◽

R. L. Peterson ◽

Dale Callaham ◽

John G. Torrey

Keyword(s):

Host Cell ◽

Root Nodules ◽

Host Cells ◽

Electron Microscopic ◽

Cortical Cells ◽

Host Cytoplasm ◽

Transmission Electron ◽

Microscopic Studies ◽

Host Plasma Membrane ◽

Soil Actinomycete

Correlated fluorescence, bright-field, transmission electron, and scanning electron microscopic studies were made on developing root nodules of Comptonia peregrina (L.) Coult. (Myricaceae) produced by a soil actinomycete which invades the root and establishes a symbiosis leading to fixation of atmospheric dinitrogen. After entering the host via a root hair infection, the hyphae of the endophyte perforate root cortical cells by local degradation of host cell walls and penetration of the host cytoplasm. The intracellular hyphae are always surrounded by host plasma membrane and a thick polysaccharide material termed the capsule. (For convenience, term intracellular refers to the endophyte being inside a Comptonia cell as distinguished from being intercellular, i.e.. between host cells, even though the former is actually extracellular as the endophyte is separated from the host cytoplasm by the host plasmalemma.) Numerous profiles of vesiculate rough endoplasmic reticulum (RER) occur near the growing hyphae. Although the capsule shows a positive Thiery reaction indicating its polysaccharide nature, the fibrillar contents of the RER do not, leaving uncertain whether the capsule results from polymers derived from the RER. Amyloplasts of the cortical cells lose their starch deposits during hyphal proliferation. The hyphae branch extensively in specific layers of the cortex, penetrating much of the host cytoplasm. At this stage, hyphal ends become swollen and form septate club-shaped vesicles within the periphery of the host cells. Lipid-like inclusions and Thiery-positive particles, possibly glycogen, are observed in the hyphae at this time. Associated with hyphal development is an increase in average host cell volume, although nuclear volume appears to remain constant. Concomitant with vesicle maturation, the mitochondrial population increases sharply, suggesting a possible relationship to vesicle function. The intimate interactions between host and endophyte during development of the symbiotic relationship are emphasized throughout.

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Aziridine-2,3-Dicarboxylate-Based Cysteine Cathepsin Inhibitors Induce Cell Death in Leishmania major Associated with Accumulation of Debris in Autophagy-Related Lysosome-Like Vacuoles

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00327-10 ◽

2010 ◽

Vol 54 (12) ◽

pp. 5028-5041 ◽

Cited By ~ 25

Author(s):

Uta Schurigt ◽

Caroline Schad ◽

Christin Glowa ◽

Ulrike Baum ◽

Katja Thomale ◽

...

Keyword(s):

Cell Death ◽

Leishmania Major ◽

Cysteine Proteinase ◽

Membrane Integrity ◽

New Drugs ◽

Host Cells ◽

Electron Microscopic ◽

Cysteine Cathepsins ◽

Cysteine Cathepsin ◽

Microscopic Studies

ABSTRACT The papain-like cysteine cathepsins expressed by Leishmania play a key role in the life cycle of these parasites, turning them into attractive targets for the development of new drugs. We previously demonstrated that two compounds of a series of peptidomimetic aziridine-2,3-dicarboxylate [Azi(OBn)2]-based inhibitors, Boc-(S)-Leu-(R)-Pro-(S,S)-Azi(OBn)2 (compound 13b) and Boc-(R)-Leu-(S)-Pro-(S,S)-Azi(OBn)2 (compound 13e), reduced the growth and viability of Leishmania major and the infection rate of macrophages while not showing cytotoxicity against host cells. In the present study, we characterized the mode of action of inhibitors 13b and 13e in L. major. Both compounds targeted leishmanial cathepsin B-like cysteine cathepsin cysteine proteinase C, as shown by fluorescence proteinase activity assays and active-site labeling with biotin-tagged inhibitors. Furthermore, compounds 13b and 13e were potent inducers of cell death in promastigotes, characterized by cell shrinkage, reduction of mitochondrial transmembrane potential, and increased DNA fragmentation. Transmission electron microscopic studies revealed the enrichment of undigested debris in lysosome-like organelles participating in micro- and macroautophagy-like processes. The release of digestive enzymes into the cytoplasm after rupture of membranes of lysosome-like vacuoles resulted in the significant digestion of intracellular compartments. However, the plasma membrane integrity of compound-treated promastigotes was maintained for several hours. Taken together, our results suggest that the induction of cell death in Leishmania by cysteine cathepsin inhibitors 13b and 13e is different from mammalian apoptosis and is caused by incomplete digestion in autophagy-related lysosome-like vacuoles.

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Differential distributions in tissues and efficacies of aztreonam and ceftazidime and in vivo bacterial morphological changes following treatment.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.2.401 ◽

1997 ◽

Vol 41 (2) ◽

pp. 401-409 ◽

Cited By ~ 2

Author(s):

A Turcotte ◽

M Simard ◽

N J Morin ◽

D Beauchamp ◽

M G Bergeron

Keyword(s):

Cell Walls ◽

Morphological Changes ◽

Enterobacter Cloacae ◽

Control Group ◽

Electron Microscopic ◽

Penetration Ratio ◽

Microscopic Studies ◽

Bow Tie ◽

Fibrin Clots

The differential tissue distributions of aztreonam and ceftazidime within fibrin clots infected with Pseudomonas aeruginosa, Enterobacter cloacae, and Serratia marcescens, their efficacies, and the in vivo bacterial morphological changes induced by these drugs were evaluated. Rabbits were given intravenously a single dose of 100 mg of either agents/kg of body weight. In the cores of the clots, the peak levels of both drugs were much lower than those observed in the peripheries and in serum. Aztreonam's half-lives within the peripheries and in the cores of the fibrin clots were up to six times higher than observed in serum, while ceftazidime's half-lives in clots were twice that observed in serum. This resulted in a much greater penetration ratio for aztreonam than for ceftazidime. Both drugs controlled the growth of P. aeruginosa in vivo, but E. cloacae and S. marcescens responded better to ceftazidime. Morphological changes were more abundant in the peripheries than in the cores of the clots. In the control group, P. aeruginosa's morphology in the cores was different than that in the peripheries of the clots. Against P. aeruginosa, aztreonam did induce morphological changes in the cores while ceftazidime did not. Electron microscopic studies revealed that morphological changes associated with aztreonam seemed different than those of ceftazidime. Along with elongation of bacteria, more bow tie and herniated bacteria were observed with aztreonam. Though both agents selectively affect PBP 3, as manifested by elongated bacteria, they induce in the peripheries of the clots thickening, breaks, and detachment in bacterial cell walls, alterations which are generally associated with antibiotics affecting PBP 1a and 1b.

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Dipotassium tetramethyl osmate: a stain for electron microscopy.

Journal of Histochemistry & Cytochemistry ◽

10.1177/23.2.1167876 ◽

1975 ◽

Vol 23 (2) ◽

pp. 123-127 ◽

Cited By ~ 5

Author(s):

C C Hinckley ◽

J A Murphy

Keyword(s):

Electron Microscopy ◽

Cell Walls ◽

Cell Ultrastructure ◽

Outer Cell ◽

Lead Citrate ◽

Electron Microscopic ◽

Methanol Solutions ◽

Microscopic Studies ◽

Cell Storage

Methanol solutions of dipotassium tetramethyl osmate (DTMO) have been found to be useful as general stains in electron microscopic studies of plant and fungal ultrastructure. The stain solutions are easy to prepare, stable when anhydrous and convenient to use. Although generally similar in staining to lead citrate stains, some elements of cell ultrastructure appear different with dipotassium tetramethyl osmate staining, particularly the outer cell walls of fungi. Indications of specific precipitate-producing reactions in cell storage areas are observed.

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CELLULAR CHARACTERISTICS OF 3 SWEET CHERRIES WITH DIFFERENT SUSCEPTIBILITIES TO RAIN CRACKING

HortScience ◽

10.21273/hortsci.27.6.667f ◽

1992 ◽

Vol 27 (6) ◽

pp. 667f-667

Author(s):

M. Meheriuk ◽

D.-L. McKenzie ◽

L. Veto

Keyword(s):

Cell Walls ◽

Mineral Content ◽

Sweet Cherry ◽

Resistant Cultivar ◽

Electron Microscopic ◽

Low Resistance ◽

Fruit Cracking ◽

Sweet Cherries ◽

Microscopic Studies ◽

Sweet Cherry Cultivars

Electron microscopic studies were conducted on `Sue', `Lapins' and `Van' sweet cherry cultivars which have a high, moderate and low resistance to rain cracking, respectively. Epidermal and hypodermal cells showed differences in size and number. Sue, the resistant cultivar, contained an additional thin elongated cell rich in protein matter, in the hypodermal layer. The three cultivars also showed differences in the cell walls and vacuoles. However, mineral content of the epidermal and hypodermal layers showed no relationship to incidence of fruit cracking.

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Resistant biomacromolecules as major contributors to kerogen

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1991.0082 ◽

1991 ◽

Vol 333 (1268) ◽

pp. 329-337 ◽

Cited By ~ 69

Keyword(s):

Cell Walls ◽

Chemical Characterization ◽

Type I ◽

Electron Microscopic ◽

Alternative Source ◽

Plant Cuticles ◽

Microscopic Studies ◽

Water Plants ◽

Waxy Crude Oils

Current research concerning the chemical characterization of organic macromolecules present in wellpreserved fossilized materials with known morphologies revealed by (electron) microscopic studies results in the recognition of unknown, resistant biomacromolecules in a variety of organisms. It is shown that highly aliphatic, non-saponifiable biomacromolecules in cell walls of algae (algaenans) have unique structures, probably as a result of different biosynthetic pathways and that they consist of n -alkyl-, isoprenoid and tricyclic alkyl units. It is also becoming clear that algaenans are structurally different from the highly aliphatic, non-saponifiable biomacromolecules occurring in plant cuticles (cutans), periderm tissue (suberans), some sporopollenins and in tegmens of seeds of water plants. All these types of aliphatic biomacromolecules are highly resistant and therefore selectively preserved in the geosphere. In particular, Type I and II kerogens consist mainly, in some cases exclusively, of these aliphatic biomacromolecules. Polysesquiterpenoids and polyditerpenoids occur in fresh and fossil angiosperm and gymnosperm resins respectively and also show resistant behaviour in the geosphere. Some waxy crude oils contain large amounts of compounds derived from these substances after thermal cracking. A completely new polyphenol type of biomacromolecule was encountered in several fossilized outer walls of seeds (testae) of water plants. Preliminary results indicate that this phenolic biomacromolecule is an alternative source of phenolic moieties in lignites and coals. The significance of lignin as a source of phenolic moieties in subsurface organic matter (e.g. vitrinites) is probably overestimated.

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Electron Microscopic Studies on Streptococci

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067960 ◽

1970 ◽

Vol 28 ◽

pp. 194-195

Author(s):

JOHN SWANSON M.D.

Keyword(s):

Cell Walls ◽

Teichoic Acid ◽

Chemical Components ◽

Group A Streptococci ◽

Electron Microscopic ◽

Histochemical Methods ◽

Specific Polysaccharide ◽

Microscopic Studies ◽

Group A ◽

Comparative Examination

Group A streptococci contain a variety of chemical components in their cell walls. The major components are mucopeptide, group-specific polysaccharide, protein constituents (M,T, and R), and teichoic acid. Investigations have been carried out to determine the location of each of these classes of chemical components. The techniques used include simple, comparative examination of selected strains that lack or possess a particular component, electron histochemical methods, immunoferritin methods, and extraction or removal of a particular component.

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Trichothecium roseum, a mycoparasite of Sclerotinia sclerotiorum

Canadian Journal of Botany ◽

10.1139/b93-198 ◽

1993 ◽

Vol 71 (12) ◽

pp. 1631-1638 ◽

Cited By ~ 18

Author(s):

H. C. Huang ◽

E. G. Kokko

Keyword(s):

Sclerotinia Sclerotiorum ◽

Cell Walls ◽

Electron Microscopic ◽

Trichothecium Roseum ◽

Moist Sand ◽

Dual Cultures ◽

Transmission Electron ◽

Bean Plants ◽

Transmission Electron Microscopic ◽

Microscopic Studies

Among sclerotia of Sclerotinia sclerotiorum collected from diseased bean plants in a field near Lethbridge in 1987 and 1988, 30 and 16%, respectively, were contaminated by Trichothecium roseum. Laboratory studies showed that T. roseum is a mycoparasite of S. sclerotiorum, able to infect and destroy sclerotia in dual cultures on potato dextrose agar. Among sclerotia inoculated with spores of T. roseum and incubated for 4 weeks on moist sand, 54 and 43% were infected and killed by the isolates TR-4 and TR-6, respectively. Transmission electron microscopic studies of infected sclerotia revealed that hyphae of T. roseum entered the rind tissue by penetrating the melanized cell walls or via junctions between cells. Lysis of host cell walls occurred at penetration sites. Hyphae of T. roseum ramified in cortical and medullary tissues, destroying the sclerotium. In sclerotia with light infections of T. roseum, numerous cortical and (or) medullary cells showed cytoplasmic granulation and vacuolization without direct association with the mycoparasitic hyphae. Key words: biocontrol, hyperparasite, mycoparasitism.

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Electron microscopic studies of fiber degradation by rumen fungi

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077645 ◽

1983 ◽

Vol 41 ◽

pp. 814-815

Author(s):

Danny E. Akin

Keyword(s):

Plant Cell ◽

Cell Walls ◽

Rumen Fluid ◽

Plant Cell Walls ◽

Host Animal ◽

Electron Microscopic ◽

Fiber Degradation ◽

Microscopic Studies ◽

Complex Ecosystem

The rumen microbial population is a complex ecosystem. Bacteria, protozoa, and fungi all play a part in degrading plant cell walls, which are a major substrate for energy and protein for the host animal. Rumen bacteria are considered to be the major degraders of forage fiber, but recent research has shown that rumen fungi are ubiquitous and are able to attack plant cell walls. Electron microscopy has been important in delineating the roles played by the various microbial types, including the fungi. The object of the present research was to assess the role of rumen fungi as degraders of particular tissues and to demonstrate that the presence of rumen fungi in the rumen can explain many of the unusual morphotypes associated with degradation of the more resistant tissues in forages.Rumen fungi were evaluated by inoculating tubes containing leaf blade sections of Cynodon dactyl on in a semi-synthetic, anaerobic medium with rumen fluid and incubating the tubes for 48 hours at 39°C. Some of the tubes contained streptomycin (2 mg/ml) and penicillin (2 x 10 units/ml) to inhibit bacteria.

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