Étude cytologique du mode d'action du capsidiol, sur les hyphes de Phytophthora capsici

After the action of capsidiol on the hyphae of Phytophthora capsici in vitro, observations with electron microscopy revealed alterations in the cell wall, in the plasmalemma, in the mitochondria, and in the Golgi system. Among other effects, phytoalexin stimulated the separation of the external cell wall layers, liberating a three-component filament. Such cytomorphological events were also recorded in situ on sections, when the fungus parasitized the leaves of Capsicum annuum. [Translated by the Journal]

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In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083035 ◽

1978 ◽

Vol 36 (2) ◽

pp. 434-435

Author(s):

D. Reis ◽

B. Vian ◽

J. C. Roland

Keyword(s):

Cell Wall ◽

Self Assembly ◽

Plant Cell Wall ◽

Higher Plants ◽

Three Dimensional ◽

Cytochemical Study ◽

Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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AN ANALYSIS OF COLLAGEN SECRETION BY ESTABLISHED MOUSE FIBROBLAST LINES

The Journal of Cell Biology ◽

10.1083/jcb.22.1.227 ◽

1964 ◽

Vol 22 (1) ◽

pp. 227-258 ◽

Cited By ~ 246

Author(s):

Burton Goldberg ◽

Howard Green

Keyword(s):

Electron Microscopy ◽

Endoplasmic Reticulum ◽

Mouse Fibroblast ◽

In Vivo Studies ◽

In Vitro Synthesis ◽

Collagen Secretion ◽

Golgi System ◽

Alternative Theories

In vitro synthesis of collagen by established mouse fibroblast lines has been examined by electron microscopy. During rapid growth (log phase), when collagen could not be detected in the cultures, the cells lacked a well developed granular ergastoplasm and Golgi system. Upon cessation of growth (stationary phase), collagen accumulated in the cultures and the cells demonstrated highly developed granular and smooth ergastoplasm. Collagen appeared to be synthesized in the rough-surfaced endoplasmic reticulum and to be transported as a soluble protein to the cell surface by vesicular elements of the agranular ergastoplasm. Fusion of the limiting membranes of these vesicles with the cell membrane permitted the discharge of the soluble collagen into the extracellular space, where fibrils of two diameter distributions formed. The secretion of collagen is concluded to be of the merocrine type. Alternative theories of collagen secretion are discussed and the data for established lines compared with the results of other in vitro and in vivo studies of collagen fibrillogenesis.

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In situ degradability of organic matter, crude protein and cell wall of various tree forages

Animal Science ◽

10.1017/s0003356100037235 ◽

1992 ◽

Vol 55 (1) ◽

pp. 29-34 ◽

Cited By ~ 18

Author(s):

P. Kamatali ◽

E. Teller ◽

M. Vanbelle ◽

G. Collignon ◽

M. Foulon

Keyword(s):

Cell Wall ◽

Organic Matter ◽

Leucaena Leucocephala ◽

Crude Protein ◽

In Vitro Digestibility ◽

Sesbania Sesban ◽

Holstein Friesian ◽

Ruminal Degradation

AbstractLeaves of Leucaena leucocephala, Sesbania sesban and Calliandra callothyrsus were harvested in Rwanda from young shoots at 8 weeks after the first cutting. They were dried, ground and incubated at the same time in polyester bags in three non-lactating Holstein-Friesian cows each fitted with a ruminal cannula. The bags were removed at 0, 2, 4, 8, 24, 48, 72 and 144 h after the start of incubations. The different parameters characterizing extent and rate of ruminal degradation of organic matter (OM), neutral-detergent fibre (NDF), and crude protein (CP) were calculated. In vitro digestibility of residual protein after 24 h and 48 h incubation was also determined. Sesbania sesban had lowest cell wall contents and gave highest ruminal degradability for OM, NDF and CP. Leucaena leucocephala was degraded to a lesser extent, but its undegraded protein had a somewhat higher in vitro digestibility. In contrast, protein of Calliandra callothyrsus was poorly degraded and digested. The proportion and composition of cell wall could not explain these differences in digestion characteristics and other measurements, such as tannins, were incriminated. Increased ruminal incubation time augmented the extent of ruminal degradation and reduced in vitro digestibility of undegraded protein but did not affect the undigestible protein fraction.

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Human β-Defensin 3 Inhibits Cell Wall Biosynthesis in Staphylococci

Infection and Immunity ◽

10.1128/iai.00688-09 ◽

2010 ◽

Vol 78 (6) ◽

pp. 2793-2800 ◽

Cited By ~ 164

Author(s):

Vera Sass ◽

Tanja Schneider ◽

Miriam Wilmes ◽

Christian Körner ◽

Alessandro Tossi ◽

...

Keyword(s):

Electron Microscopy ◽

Cell Wall ◽

Host Defense ◽

Transcriptional Response ◽

Cell Wall Biosynthesis ◽

Host Defense Peptides ◽

Lipid Ii ◽

Transmission Electron ◽

Host Defense Peptide

ABSTRACT Human β-defensin 3 (hBD3) is a highly charged (+11) cationic host defense peptide, produced by epithelial cells and neutrophils. hBD3 retains antimicrobial activity against a broad range of pathogens, including multiresistant Staphylococcus aureus, even under high-salt conditions. Whereas antimicrobial host defense peptides are assumed to act by permeabilizing cell membranes, the transcriptional response pattern of hBD3-treated staphylococcal cells resembled that of vancomycin-treated cells (V. Sass, U. Pag, A. Tossi, G. Bierbaum, and H. G. Sahl, Int. J. Med. Microbiol. 298:619-633, 2008) and suggested that inhibition of cell wall biosynthesis is a major component of the killing process. hBD3-treated cells, inspected by transmission electron microscopy, showed localized protrusions of cytoplasmic contents, and analysis of the intracellular pool of nucleotide-activated cell wall precursors demonstrated accumulation of the final soluble precursor, UDP-MurNAc-pentapeptide. Accumulation is typically induced by antibiotics that inhibit membrane-bound steps of cell wall biosynthesis and also demonstrates that hBD3 does not impair the biosynthetic capacity of cells and does not cause gross leakage of small cytoplasmic compounds. In in vitro assays of individual membrane-associated cell wall biosynthesis reactions (MraY, MurG, FemX, and penicillin-binding protein 2 [PBP2]), hBD3 inhibited those enzymes which use the bactoprenol-bound cell wall building block lipid II as a substrate; quantitative analysis suggested that hBD3 may stoichiometrically bind to lipid II. We report that binding of hBD3 to defined, lipid II-rich sites of cell wall biosynthesis may lead to perturbation of the biosynthesis machinery, resulting in localized lesions in the cell wall as demonstrated by electron microscopy. The lesions may then allow for osmotic rupture of cells when defensins are tested under low-salt conditions.

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1.14 Structure Determination of Macromolecular Complexes by Cryo-Electron Microscopy in vitro and in situ

Comprehensive Biophysics ◽

10.1016/b978-0-12-374920-8.00118-1 ◽

2012 ◽

pp. 245-276

Author(s):

F. Förster ◽

E. Villa ◽

D. Thomas ◽

A. Korinek ◽

W. Baumeister

Keyword(s):

Electron Microscopy ◽

Structure Determination ◽

Macromolecular Complexes ◽

Cryo Electron Microscopy

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Adhesion of Hydroxyapatite Nanoparticles to Dental Materials under Oral Conditions

Scanning ◽

10.1155/2020/6065739 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12 ◽

Cited By ~ 4

Author(s):

Cíntia Mirela Guimarães Nobre ◽

Norbert Pütz ◽

Matthias Hannig

Keyword(s):

Electron Microscopy ◽

Dental Materials ◽

Hydroxyapatite Nanoparticles ◽

Pellicle Formation ◽

Transmission Electron ◽

Different Shapes ◽

Oral Conditions ◽

Dental Applications

Hydroxyapatite nanoparticles (nano-HAP) are receiving considerable attention for dental applications, and their adhesion to enamel is well established. However, there are no reports concerning the effects of HAP on other dental materials, and most of the studies in this field are based on in vitro designs, neglecting the salivary pellicle-apatite interactions. Thus, this in situ pilot study aims to evaluate the effects of three hydroxyapatite-based solutions and their interactions with different dental material surfaces under oral conditions. Hence, two volunteers carried intraoral splints with mounted samples from enamel and from three dental materials: titanium, ceramics, and polymethyl-methacrylate (PMMA). Three HAP watery solutions (5%) were prepared with different shapes and sizes of nano-HAP (HAP I, HAP II, HAP III). After 3 min of pellicle formation, 10 ml rinse was performed during 30 sec. Rinsing with water served as control. Samples were accessed immediately after rinsing, 30 min and 2 h after rinsing. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the particles, and SEM evaluated the pellicle-HAP interactions. SEM and TEM results showed a high variation in the size range of the particles applied. A heterogeneous HAP layer was present after 2 h on enamel, titanium, ceramics, and PMMA surfaces under oral conditions. Bridge-like structures were visible between the nano-HAP and the pellicle formed on enamel, titanium, and PMMA surfaces. In conclusion, nano-HAP can adhere not only to enamel but also to artificial dental surfaces under oral conditions. The experiment showed that the acquired pellicle act as a bridge between the nano-HAP and the materials’ surface.

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Generation of flagella by cultured mouse spermatids.

The Journal of Cell Biology ◽

10.1083/jcb.98.2.619 ◽

1984 ◽

Vol 98 (2) ◽

pp. 619-628 ◽

Cited By ~ 35

Author(s):

G L Gerton ◽

C F Millette

Keyword(s):

Electron Microscopy ◽

Spermatogenic Cells ◽

Fibrous Sheath ◽

Acridine Orange Staining ◽

Transmission Electron ◽

Fetal Bovine ◽

Outer Dense Fibers ◽

Unit Gravity Sedimentation

During the short-term culturing of mouse spermatogenic cells, flagella were generated by round spermatids previously lacking tails. Unseparated germ cells were obtained by enzymatic treatments and round spermatids (greater than 90% pure) were purified by unit gravity sedimentation. As determined by Nomarski or phase-contrast microscopy, no cells had flagella immediately after isolation; flagella were first clearly detected after 6 1/2 h of culture in Eagle's minimal essential medium containing 10% fetal bovine serum and 6 mM lactate. After 24 h, approximately 20% of round spermatids had formed flagella. Multinucleated round spermatids often formed multiple flagella, the number never exceeding the number of nuclei per symplast. Round spermatids were the only spermatogenic cells capable of tail formation. Flagella elongation was blocked by 1 microM demecolcine, an inhibitor of tubulin polymerization. Indirect immunofluorescence localized tubulin in the flagella. As seen by scanning electron microscopy, flagella developed as early as 2 h after culture and continued to elongate over the next 20 h, reaching lengths of at least 19 micron. Transmission electron microscopy demonstrated that flagella formed in culture resembled flagella from Golgi-phase round spermatids in situ; the flagella consisted of "9+2" axonemes lacking other accessory structures such as outer dense fibers and the fibrous sheath. As determined by acridine orange staining of the developing acrosomes, all spermatids that formed flagella in culture were Golgi-phase spermatids. By these criteria, the structures are indeed true flagella, corresponding in appearance to what others have described for early mammalian spermatid flagella in situ. We believe this is the first substantiated report of limited in vitro differentiation by isolated mammalian spermatids.

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A comparative study of ruminal activity in Churra and Merino sheep offered alfalfa hay

Animal Science ◽

10.1017/s1357729800016374 ◽

1997 ◽

Vol 65 (1) ◽

pp. 121-128 ◽

Cited By ~ 21

Author(s):

M. J. Ranilla ◽

M. D. Carro ◽

C. Valdés ◽

F. J. Giráldez ◽

S. López

Keyword(s):

Cell Wall ◽

Rumen Fluid ◽

Merino Sheep ◽

Rumen Ph ◽

Sheep Rumen ◽

Fermentation Parameters ◽

Micro Organisms ◽

Kinetics Of

AbstractA study was carried out to compare the fermentation parameters and kinetics of digestion of a range of different foods in the rumen of two breeds of sheep (Churra and Merino). Ten mature sheep (five Churra and five Merino), each fitted with a rumen cannula, were used in this study. In situ rumen degradability of both dry matter (DM) and cell wall was greater in Churra than in Merino sheep, the breed differences being significant for most of the foods used in the study (P < 0·05). These differences were greater when the foods had a higher cell wall concentration and this could be related to differences in the ruminal environment. However, when the foods were incubated with rumen fluid their in vitro organic matter (OM) degradability was similar in both breeds. Rumen pH was higher (P < 0·05) and ammonia concentrations were lower (P < 0·05) in Churra than in Merino sheep. Rumen volatile fatty acid concentrations tended to be higher in Merino than in Churra sheep, though differences were only significant just before feeding (P < 0·05). The ratio acetate: propionate was higher in the Churra than Merino breed before and 12 h after feeding (P < 0·05). Protozoa numbers in rumen liquid were similar for both genotypes. The greater degradation of forages in the rumen of Churra sheep is discussed in relation to the possible higher activity of fibre-degrading micro-organisms and the greater buffering capacity of the rumen contents against fermentation acids, which could result in more favourable conditions for the microbial degradation of foods in the rumen.

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Perlakuan Benih Cabai (Capsicum annuum L.) dengan Rizobakteri untuk Mengendalikan Phytophthora capsici, Meningkatkan Vigor Benih dan Pertumbuhan Tanaman

Buletin Agrohorti ◽

10.29244/agrob.2.1.22-30 ◽

2014 ◽

Vol 2 (1) ◽

pp. 22

Author(s):

Abubakar Ibrahim ◽

Satriyas Ilyas ◽

Dyah Manohara

Keyword(s):

Capsicum Annuum ◽

Phytophthora Capsici ◽

Capsicum Annuum L

Perlakuan benih menggunakan rizobakteri sebagai alternatif pengganti penggunaan bahan kimia untuk mengendalikan penyakit tanaman. Penelitian ini bertujuan (1) menyeleksi keefektifan isolat rizobakteri dalam menghambat pertumbuhan Phytophthora capsici secara in vitro, dan (2) mempelajari pengaruh perlakuan benih menggunakan rizobakteri terhadap pertumbuhan P. capsici, vigor benih dan pertumbuhan tanaman. Penelitian ini terdiri atas dua tahap percobaan, kedua percobaan tersebut menggunakan rancangan acak lengkap. Percobaan satu (pesemaian) terdiri atas lima taraf yaitu perlakuan benih dengan rizobakteri ST116B, ST156, E3, metalaksil, dan tanpa perlakuan (kontrol). Percobaan dua (di rumah kaca) terdiri atas enam taraf yaitu perlakuan rizobakteri ST116B, ST156, E3, metalaksil, kontrol positif, dan kontrol negatif. Terdapat 7 rizobakteri dari 23 isolat yang diuji yaitu ST156, E3, ST116B, ST81, SK7, ST116, dan ST109B menghambat pertumbuhan P. capsici secara in vitro. Perlakuan benih dengan rizobakteri ST116B, ST156, dan E3 nyata meningkatkan vigor benih pada tolok ukur indeks vigor. Perlakuan benih terbaik dalam meningkatkan pertumbuhan tanaman (jumlah daun) dan berpotensi mengendalikan penyakit busuk phytophthora pada tanaman cabai adalah dengan rizobakteri ST116B.

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Engineering of Chitosan-Hydroxyapatite-Magnetite Hierarchical Scaffolds for Guided Bone Growth

Materials ◽

10.3390/ma12142321 ◽

2019 ◽

Vol 12 (14) ◽

pp. 2321 ◽

Cited By ~ 12

Author(s):

Pistone ◽

Celesti ◽

Piperopoulos ◽

Ashok ◽

Cembran ◽

...

Keyword(s):

Electron Microscopy ◽

Bone Growth ◽

Cell Attachment ◽

X Ray Diffraction ◽

Culture Studies ◽

X Ray ◽

Support Cell ◽

Chitosan Matrix

Bioabsorbable materials have received increasing attention as innovative systems for the development of osteoconductive biomaterials for bone tissue engineering. In this paper, chitosan-based composites were synthesized adding hydroxyapatite and/or magnetite in a chitosan matrix by in situ precipitation technique. Composites were characterized by optical and electron microscopy, thermogravimetric analyses (TGA), x-ray diffraction (XRD), and in vitro cell culture studies. Hydroxyapatite and magnetite were found to be homogeneously dispersed in the chitosan matrix and the composites showed superior biocompatibility and the ability to support cell attachment and proliferation; in particular, the chitosan/hydroxyapatite/magnetite composite (CS/HA/MGN) demonstrated superior bioactivity with respect to pure chitosan (CS) and to the chitosan/hydroxyapatite (CS/HA) scaffolds

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