The effect of the hydrocarbon naphthalene on the morphology of the green flagellate Chlamydomonas angulosa

1979 ◽  
Vol 57 (24) ◽  
pp. 2729-2739 ◽  
Author(s):  
C. Soto ◽  
J. A. Hellebust ◽  
T. C. Hutchinson ◽  
R. G. Sheath
Keyword(s):  
Cell Wall ◽  
Crude Oil ◽  
Morphological Changes ◽  
Ultrastructural Changes ◽  
Hollow Core ◽  
Sudan Black B ◽  
Cytoplasmic Vacuoles ◽  
Osmiophilic Granules ◽  
Peripheral Structure ◽  
Green Flagellate

The morphological changes of Chlamydomonas angulosa, when incubated with a 50% saturated solution of the aromatic hydrocarbon naphthalene, have been studied. Comparisons are made with the effects of crude oil. Observations under the light microscope reveal a totally inhibited motility, loss of flagella, an increase in the activity of the contractile vacuoles, and the appearance of cytoplasmic granulation. The cells were found to develop a surrounding transparent envelope. With electron microscopy, the following ultrastructural changes were revealed: the cell wall became partially thickened and a widened space developed between the cell wall and the plasmalemma; abnormal chloroplast lamellae developed, composed of numerous thylakoids; starch grains increased in number and in size; the osmiophilic granules of the stigma became a hollow core with peripheral structure and electron-dense material became heavily deposited inside the cytoplasmic vacuoles. This material stained deeply with Sudan black B, indicating its lipid nature. No recovery of cells was found during the 8-day incubation period with naphthalene, in contrast to recoveries noted with crude oil treatment. The lipid deposits in the vacuole also showed no indication of migration or reduction during this period.

The effect of crude oil on the morphology of the green flagellate Chlamydomonas angulosa

1979 ◽  
Vol 57 (24) ◽  
pp. 2717-2728 ◽  
Author(s):  
C. Soto ◽  
T. C. Hutchinson ◽  
J. A. Hellebust ◽  
R. G. Sheath
Keyword(s):  
Crude Oil ◽  
Morphological Changes ◽  
Exponential Phase ◽  
Ultrastructural Changes ◽  
Cytoplasmic Vacuoles ◽  
Dense Deposits ◽  
Osmiophilic Granules ◽  
Green Flagellate ◽  
Oil Extract ◽  
Increased Activity

The morphological changes of Chlamydomonas angulosa induced by treatment with an aqueous crude oil extract (ACOE) have been studied and compared with normal cells in the exponential phase of growth. Observations of oil-treated cells under the light microscope showed an effect on flagellar length and on motility, an increased activity of the contractile vacuoles, and an increase in granulations. Cells so treated become surrounded by a transparent envelope. By electron microscopy, the progression of ultrastructural changes has been followed. These changes include: a widened space between the cell wall and the plasmalemma; distorted and disorganized chloroplast lamellae; a decrease in density of the osmiophilic granules; and the presence of electron-dense deposits inside the cytoplasmic vacuoles. Cells were found to possess the ability to recover from the above abnormalities within an 8-day incubation period. Such a recovery corresponds to resumption of motility, capacity for growth, and photosynthesis, as described in other work. Based both on appearance, and on comparisons with bacterial, fungal studies, and cytochemical studies, it is suggested that the osmiophilic granules are lipid in nature and may act as a hydrocarbon sink. A self-cleansing mechanism is also suggested for these granules.

Ultrastructural changes in the myxamoebae of Physarum polycephalum in response to a microcyst-inducing concentration of mannitol

1984 ◽  
Vol 62 (2) ◽  
pp. 272-280 ◽  
Author(s):  
Lynda M. Williams ◽  
Jean-G. Lafontaine
Keyword(s):  
Cell Wall ◽  
Osmotic Potential ◽  
Physarum Polycephalum ◽  
Morphological Changes ◽  
Ruthenium Red ◽  
Ultrastructural Changes ◽  
Wall Material ◽  
Cell Wall Material ◽  
Cell Coat ◽  
Ruthenium Red Staining

The response of axenically cultured Physarum polycephalum myxamoebae to a microcyst-inducing concentration of mannitol (0.5 M) has been studied for both log-phase and maximum-concentration cultures. Results indicate that mannitol alone is not sufficient to induce encystment; a population effect is also necessary. Myxamoebae may continue to divide in the presence of mannitol if this effect is absent. Early ultrastructural changes have been noted indicating that the primary mode of action of mannitol is via the change in osmotic potential of the medium. Nuclear and cytoplasmic ultrastructural changes during the encystment process are documented. Recovery of log-phase cells to undergo mitosis involves definite morphological changes, which are also described. Ruthenium red staining was utilised to emphasize changes in the cell coat and indicate possible sites of accumulation of cell wall material.

Ultrastructure and Senescence in an Achloroplastic Mutant of Hordeum vulgare L. cv. Dyan

1992 ◽  
Vol 50 (1) ◽  
pp. 844-845
Author(s):  
R.H.M. Cross ◽  
C.E.J. Botha ◽  
A.K. Cowan ◽  
B.J. Hartley
Keyword(s):  
Cell Wall ◽  
Hordeum Vulgare ◽  
Leaf Tissue ◽  
Ultrastructural Changes ◽  
Hordeum Vulgare L ◽  
Mesophyll Cells ◽  
Lethal Mutant ◽  
Cytoplasmic Matrix ◽  
Close Proximity ◽  
Pinocytotic Vesicles

Senescence is an ordered degenerative process leading to death of individual cells, organs and organisms. The detection of a conditional lethal mutant (achloroplastic) of Hordeum vulgare has enabled us to investigate ultrastructural changes occurring in leaf tissue during foliar senescence.Examination of the tonoplast structure in six and 14 day-old mutant tissue revealed a progressive degeneration and disappearance of the membrane, apparently starting by day six in the vicinity of the mitochondria associated with the degenerating proplastid (Fig. 1.) where neither of the plastid membrane leaflets is evident (arrows, Fig. 1.). At this stage there was evidence that the mitochondrial membranes were undergoing retrogressive changes, coupled with disorganization of cristae (Fig. 2.). Proplastids (P) lack definitive prolamellar bodies. The cytoplasmic matrix is largely agranular, with few endoplasmic reticulum (ER) cisternae or polyribosomal aggregates. Interestingly, large numbers of actively-budding dictysomes, associated with pinocytotic vesicles, were observed in close proximity to the plasmalemma of mesophyll cells (Fig. 3.). By day 14 however, mesophyll cells showed almost complete breakdown of subcellular organelle structure (Fig. 4.), and further evidence for the breakdown of the tonoplast. The final stage of senescence is characterized by the solubilization of the cell wall due to expression and activity of polygalacturonase and/or cellulose. The presence of dictyosomes with associated pinocytotic vesicles formed from the mature face, in close proximity to both the plasmalemma and the cell wall, would appear to support the model proposed by Christopherson for the secretion of cellulase. This pathway of synthesis is typical for secretory glycoproteins.

scholarly journals Cell wall and organelle modifications during nitrogen starvation in Nannochloropsis oceanica F&M-M24

2021 ◽  
Author(s):  
Roncaglia Bianca ◽  
Papini Alessio ◽  
Chini Zittelli Graziella ◽  
Rodolfi Liliana ◽  
Mario R. Tredici
Keyword(s):  
Cell Wall ◽  
Wall Thickness ◽  
Lipid Droplets ◽  
Nitrogen Starvation ◽  
Photosynthetic Apparatus ◽  
Ultrastructural Changes ◽  
Total Biomass ◽  
Nannochloropsis Oceanica ◽  
Final Phase ◽  
Cell Functions

AbstractNannochloropsis oceanica F&M-M24 is able to increase its lipid content during nitrogen starvation to more than 50% of the total biomass. We investigated the ultrastructural changes and the variation in the content of main cell biomolecules that accompany the final phase of lipid accumulation. Nitrogen starvation induced a first phase of thylakoid disruption followed by chloroplast macroautophagy and formation of lipid droplets. During this phase, the total amount of proteins decreased by one-third, while carbohydrates decreased by 12–13%, suggesting that lipid droplets were formed by remodelling of chloroplast membranes and synthesis of fatty acids from carbohydrates and amino acids. The change in mitochondrial ultrastructure suggests also that these organelles were involved in the process. The cell wall increased its thickness and changed its structure during starvation, indicating that a disruption process could be partially affected by the increase in wall thickness for biomolecules recovery from starved cells. The wall thickness in strain F&M-M24 was much lower than that observed in other strains of N. oceanica, showing a possible advantage of this strain for the purpose of biomolecules extraction. The modifications following starvation were interpreted as a response to reduction of availability of a key nutrient (nitrogen). The result is a prolonged survival in quiescence until an improvement of the environmental conditions (nutrient availability) allows the rebuilding of the photosynthetic apparatus and the full recovery of cell functions.

scholarly journals Structures of the surface exposed proteins of Gram positive bacteria

2014 ◽  
Vol 70 (a1) ◽  
pp. C432-C432
Author(s):  
George Minasov ◽  
Salvatore Nocadello ◽  
Ekaterina Filippova ◽  
Andrei Halavaty ◽  
Wayne Anderson
Keyword(s):  
Cell Wall ◽  
Infectious Diseases ◽  
Bacillus Anthracis ◽  
Structural Genomics ◽  
Drug Targets ◽  
Morphological Changes ◽  
Target Selection ◽  
Surface Proteins ◽  
Human Pathogens ◽  
Gram Positive

The Center for Structural Genomics for Infectious Diseases (CSGID) applies structural genomics approaches to biomedically important proteins from human pathogens. It also provides the infectious disease community with a high throughput pipeline for structure determination that carries out all steps of the process, from target selection through structure deposition. Target proteins include drug targets, essential enzymes, virulence factors and vaccine candidates. The CSGID has deposited over 680 structures in the Protein Data Bank. The proteins that are exposed on the surface of Gram positive bacterial pathogens (including Staphylococcus aureus, Bacillus anthracis, Listeria monocytogenes, Streptococcus species and Clostridium species) have been one focus area for the CSGID. So far, the structures of more than 55 of these proteins have been determined. The surface proteins are important in the interactions between the pathogen and its host, but many of them are as yet functionally uncharacterized. Among the examples that will be presented is the Bacillus anthracis SpoIID protein. SpoIID is part of a coordinated cell wall degradation machine that is essential for sporulation and the morphological changes involved. It represents a new family of lytic transglycosylases that degrade the glycan strands of the peptidoglycan cell wall. The two active site clefts in the dimeric enzyme include residues from both subunits, suggesting that the dimer is required for activity. This project has been funded in whole or in part with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contracts No. HHSN272200700058C and HHSN272201200026C.

scholarly journals Microstructure of thermally modified radiata pine wood

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 1523-1533
Author(s):  
José Luis Cabezas-Romero ◽  
Linette Salvo-Sepúlveda ◽  
Helga Contreras-Moraga ◽  
Natalia Pérez-Peña ◽  
Víctor Sepúlveda-Villarroel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Wood Cell Wall ◽  
Morphological Changes ◽  
Untreated Wood ◽  
Radiata Pine ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Modification Process ◽  
Potential Alternative ◽  
Two Temperatures

The thermal modification of wood is a potential alternative method for improving wood dimensional stability and increasing the resistance of wood to decay. However, during thermal modification, morphological changes occur within the microstructure of the cell, and these confer different properties to the wood. This study investigated the effects of the thermal modification process on the microstructure of radiata pine juvenile wood. Therefore, anatomical measurements were performed via optical microscopy in selected earlywood and latewood samples after each treatment, and the results were compared to untreated wood samples. In this study, two temperatures (190 °C and 210 °C) were considered for the thermal modification process. The results showed that the level of temperature of modification affected to microstructure of cell wall. The cell wall thickness decreased as treatment temperature increased, whereas the average lumen diameter increased slightly as temperature increased. Thermally modified radiata pine showed signs of damage (cracks, broken cells and deformations in the wood cell wall). The proportion of destroyed area increased as temperature increased, and significant differences were evident for the thermal treatment at 210 °C.

scholarly journals An ABC transporter Wzm–Wzt catalyzes translocation of lipid-linked galactan across the plasma membrane in mycobacteria

2021 ◽  
Vol 118 (17) ◽  
pp. e2023663118
Author(s):  
Karin Savková ◽  
Stanislav Huszár ◽  
Peter Baráth ◽  
Zuzana Pakanová ◽  
Stanislav Kozmon ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Abc Transporter ◽  
Morphological Changes ◽  
Transport Systems ◽  
Host Immune System ◽  
Mycolic Acids ◽  
Cell Wall Biogenesis ◽  
Covalently Linked ◽  
High Level

Mycobacterium tuberculosis, one of the deadliest pathogens in human history, is distinguished by a unique, multilayered cell wall, which offers the bacterium a high level of protection from the attacks of the host immune system. The primary structure of the cell wall core, composed of covalently linked peptidoglycan, branched heteropolysaccharide arabinogalactan, and mycolic acids, is well known, and numerous enzymes involved in the biosynthesis of its components are characterized. The cell wall biogenesis takes place at both cytoplasmic and periplasmic faces of the plasma membrane, and only recently some of the specific transport systems translocating the metabolic intermediates between these two compartments have been characterized [M. Jackson, C. M. Stevens, L. Zhang, H. I. Zgurskaya, M. Niederweis, Chem. Rev., 10.1021/acs.chemrev.0c00869 (2020)]. In this work, we use CRISPR interference methodology in Mycobacterium smegmatis to functionally characterize an ATP-binding cassette (ABC) transporter involved in the translocation of galactan precursors across the plasma membrane. We show that genetic knockdown of the transmembrane subunit of the transporter results in severe morphological changes and the accumulation of an aberrantly long galactan precursor. Based on similarities with structures and functions of specific O-antigen ABC transporters of gram-negative bacteria [C. Whitfield, D. M. Williams, S. D. Kelly, J. Biol. Chem. 295, 10593-10609 (2020)], we propose a model for coupled synthesis and export of the galactan polymer precursor in mycobacteria.

Morphological changes in putrefactive anaerobe 3679 (Clostridium sporogenes) induced by sorbate, hydrochloric acid, and nitrite

1989 ◽  
Vol 35 (3) ◽  
pp. 388-398 ◽  
Author(s):  
Irene E. Ronning ◽  
Hilmer A. Frank
Keyword(s):  
Cell Wall ◽  
Hydrochloric Acid ◽  
Growth Regulation ◽  
Morphological Changes ◽  
Light And Electron Microscopy ◽  
Normal Growth ◽  
Outer Wall ◽  
Exponential Growth Phase ◽  
Clostridium Sporogenes ◽  
Cellular Debris

Putrefactive anaerobe 3679 (Clostridium sporogenes), a gram-positive bacterium, was examined by light and electron microscopy during normal growth and in a medium containing sorbate (50 mM, pH 6.5), hydrochloric acid (pH of medium adjusted from 7 to 5 with HCl), or nitrite (1 mM, pH 7). During the early exponential growth phase, untreated cells were filamentous and nonseptate, but became septate later and divided when the culture entered the stationary phase. Untreated short and filamentous cells had a double-layered cell wall. Sorbate-treated cells were usually filamentous and nonseptate, but with distorted shapes characterized by numerous bends and bulges. Septation, when present, resulted in minicells. The inner cell wall appeared to be thickened and the outer wall was absent in many areas. Acid-treated cells were similar to sorbate-treated cells but contained septa. Considerable cellular debris was present in the suspension. Nitrite-treated cells were also filamentous, bent, and bulged but the cell wall appeared normal. Considerable cellular debris was also present in suspensions of nitrite-treated cells. Changes in morphology are discussed in relation to possible mechanisms of cell growth regulation and the inhibitory action of sorbate, acid, and nitrite.Key words: putrefactive anaerobe 3679, sorbate, hydrochloric acid, nitrite.

scholarly journals Latency- and Defense-Related Ultrastructural Characteristics of Apple Fruit Tissues Infected with Botryosphaeria dothidea

2001 ◽  
Vol 91 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Ki Woo Kim ◽  
Eun Woo Park ◽  
Young Ho Kim ◽  
Kyung-Ku Ahn ◽  
Pan Gi Kim ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fungal Growth ◽  
Apple Fruit ◽  
White Rot ◽  
Ultrastructural Changes ◽  
Disease Development ◽  
Botryosphaeria Dothidea ◽  
Transmission Electron ◽  
Thin Electron ◽  
Apple Fruits

Apple fruit tissues infected with Botryosphaeria dothidea were examined by transmission electron microscopy using susceptible cv. Fuji and resistant cv. Jonathan. Immature (green) and mature (red) fruits of cv. Fuji with restricted or expanding lesions were also examined to reveal subcellular characteristics related with latent and restricted disease development. In infected susceptible mature fruits, cytoplasmic degeneration and organelle disruption commonly occurred, accompanying cell wall dissolution around invading hyphae. Cell wall dissolution around invading hyphae in subepidermis was rare in immature, red halo-symptomed cv. Fuji and resistant cv. Jonathan fruits. In infected immature fruits of cv. Fuji, presumably at the latent state of disease development, cellular degeneration was less severe, and invading hyphae contained prominent microbody-lipid globule complexes or the deposition of thin electron-dense outer layer around cell wall of intercellular hyphae. Both mature fruits with red halos and resistant apple fruits formed cell wall protuberances at the outside of cell walls. In addition, electron-dense extramural layers were formed in the resistant apple fruits. Aberrant hyphal structures such as intrahyphal hyphae were found only in resistant fruit tissues, indicating the physiologically altered fungal growth. These ultrastructural changes of host tissues and fungal hyphae may reflect the pathogenesis of apple white rot under varying conditions of apple fruits.

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