scholarly journals THE FINE STRUCTURE OF ACANTHAMOEBA CASTELLANII (NEFF STRAIN)

1969 ◽  
Vol 41 (3) ◽  
pp. 786-805 ◽  
Author(s):  
Blair Bowers ◽  
Edward D. Korn
Keyword(s):  
Golgi Complex ◽  
Cyst Wall ◽  
Matrix Material ◽  
Acanthamoeba Castellanii ◽  
Dry Weight ◽  
Amorphous Layer ◽  
Wall Structure ◽  
Weight Protein ◽  
Granular Matrix ◽  
Mature Cyst

Encysting cells of Acanthamoeba castellanii, Neff strain, have been examined with the electron microscope. The wall structure and cytoplasmic changes during encystment are described. The cyst wall is composed of two major layers: a laminar, fibrous exocyst with a variable amount of matrix material, and an endocyst of fine fibrils in a granular matrix. The two layers are normally separated by a space except where they form opercula in the center of ostioles (exits for excysting amebae). An additional amorphous layer is probably present between the wall and the protoplast in the mature cyst. Early in encystment the Golgi complex is enlarged and contains a densely staining material that appears to contribute to wall formation. Vacuoles containing cytoplasmic debris (autolysosomes) are present in encysting cells and the contents of some of the vacuoles are deposited in the developing cyst wall. Lamellate bodies develop in the mitochondria and appear in the cytoplasm. Several changes are associated with the mitochondrial intracristate granule. The nucleus releases small buds into the cytoplasm, and the nucleolus decreases to less than half its original volume. The cytoplasm increases in electron density and its volume is reduced by about 80%. The water expulsion vesicle is the only cellular compartment without dense content in the mature cyst. The volume fractions of lipid droplets, Golgi complex, mitochondria, digestive vacuoles, and autolysosomes have been determined at different stages of encystment by stereological analysis of electron micrographs. By chemical analyses, dry weight, protein, phospholipid, and glycogen are lower and neutral lipid is higher in the mature cyst than in the trophozoite.

scholarly journals Three stages in the development of the cyst wall of the eye pathogen Acanthamoeba castellanii

2019 ◽  
Author(s):  
Pamela Magistrado-Coxen ◽  
Yousuf Aqeel ◽  
A Lopez ◽  
John Samuelson
Keyword(s):  
Cyst Wall ◽  
Acanthamoeba Castellanii ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Eye Infections ◽  
Second Stage ◽  
Sequence Of Events ◽  
Starting Point ◽  
Third Stage ◽  
Mature Cyst

AbstractWhen deprived of nutrients, trophozoites of the eye pathogen Acanthamoeba castellanii make a cyst wall, which contains cellulose and has two layers connected by cone-shaped ostioles. We recently showed chitin is also present and identified three sets of lectins, which localize to the ectocyst layer (Jonah lectin) or the endocyst layer and ostioles (Luke and Leo lectins). To determine how the cyst wall is made, we examined encysting protists using structured illumination microscopy, probes for glycopolymers, and tags for lectins. In the first stage (3 to 9 hr), cellulose, chitin, and a Jonah lectin were each made in dozens of encystation-specific vesicles. In the second stage (12 to 18 hr), a primordial wall contained both glycopolymers and Jonah lectin, while small, flat ostioles were outlined by a Luke lectin. In the third stage (24 to 36 hr), an ectocyst layer enriched in Jonah lectin was connected to an endocyst layer enriched in Luke and Leo lectins by large, conical ostioles. Jonah and Luke lectins localized to the same places in mature cyst walls (72 hr) independent of the timing of expression. The Jonah lectin and the glycopolymer bound by the lectin were accessible in the ectocyst layer of mature walls. In contrast, Luke and Leo lectins and glycopolymers bound by the lectins were mostly inaccessible in the endocyst layer and ostioles. These results show that cyst wall formation is a tightly choreographed event, in which glycopolymers and lectins combine to form a mature wall with a protected endocyst layer.ImportanceWhile the cyst wall of Acanthamoeba castellanii, cause of eye infections, contains cellulose like plants and chitin like fungi, it is a temporary, protective structure, analogous to spore coats of bacteria. We showed here that, unlike plants and fungi, A. castellanii makes cellulose and chitin in encystation-specific vesicles. The outer and inner layers of cyst walls, which resemble the primary and secondary walls of plant cells, respectively, are connected by unique structures (ostioles) that synchronously develop from small, flat circles to large, conical structures. Cyst wall proteins, which are lectins that bind cellulose and chitin, localize to inner or outer layers independent of the timing of expression. Because of its abundance and accessibility in the outer layer, the Jonah lectin is an excellent target for diagnostic antibodies. A description of the sequence of events during cyst wall development is a starting point for mechanistic studies of its assembly.

scholarly journals THE FINE STRUCTURE OF ACANTHAMOEBA CASTELLANII

1968 ◽  
Vol 39 (1) ◽  
pp. 95-111 ◽  
Author(s):  
Blair Bowers ◽  
Edward D. Korn
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Cell Surface ◽  
Golgi Complex ◽  
Acanthamoeba Castellanii ◽  
Dry Weight ◽  
Dense Material ◽  
Fibrillar Material ◽  
Cytoplasmic Microtubules ◽  
Filamentous Material

The fine structure of the trophozoite of Acanthamoeba castellanii (Neff strain) has been studied. Locomotor pseudopods, spikelike "acanthopodia," and microprojections from the cell surface are all formed by hyaline cytoplasm, which excludes formed elements of the cell and contains a fine fibrillar material. Golgi complex, smooth and rough forms of endoplasmic reticulum, digestive vacuoles, mitochondria, and the water-expulsion vesicle (contractile vacuole) are described. A canicular system opening into the water-expulsion vesicle contains tubules about 600 A in diameter that are lined with a filamentous material. The tubules are continuous with unlined vesicles or ampullae of larger diameter. Centrioles were not observed, but cytoplasmic microtubules radiate from a dense material similar to centriolar satellites and are frequently centered in the Golgi complex. Cytoplasmic reserve materials include both lipid and glycogen, each of which amounts to about 10% of the dry weight.

scholarly journals The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls

2019 ◽  
Vol 13 (5) ◽  
pp. e0007352 ◽  
Author(s):  
Pamela Magistrado-Coxen ◽  
Yousuf Aqeel ◽  
Angelo Lopez ◽  
John R. Haserick ◽  
Breeanna R. Urbanowicz ◽  
...  
Keyword(s):  
Cyst Wall ◽  
Acanthamoeba Castellanii ◽  
Mature Cyst

Cyst and germ tube wall structure in Aphanomyces astaci, Oomycetes

1978 ◽  
Vol 24 (11) ◽  
pp. 1296-1299 ◽  
Author(s):  
Lars Nyhlén ◽  
Torgny Unestam
Keyword(s):  
Alkaline Hydrolysis ◽  
Cyst Wall ◽  
Germ Tube ◽  
Tube Wall ◽  
Amorphous Layer ◽  
Wall Structure ◽  
Wall Surface ◽  
Aphanomyces Astaci ◽  
Shadow Casting ◽  
Staining Techniques

Aphanomyces astaci secondary cyst walls and walls of germinating spores were prepared by alkaline hydrolysis, autolysis, sonication, and enzymic degradation and were examined by shadow-casting and negative-staining techniques. The cyst wall consists of randomly oriented fibrils, about 3 nm in diameter. The fibrils are embedded in, or covered by, amorphous β-1,3-glucans which can easily be removed by alkaline hydrolysis. The germ tube wall surface has the same structure, but the amorphous layer is less easily removed.

scholarly journals Large scale laboratory cultures of Ankistrodesmus gracilis (Reisch) Korsikov (Chlorophyta) and Diaphanosoma biergei Korinek, 1981 (Cladocera)

2008 ◽  
Vol 68 (4) ◽  
pp. 875-883 ◽  
Author(s):  
LH. Sipaúba-Tavares ◽  
AML. Pereira
Keyword(s):  
Exponential Growth ◽  
Large Scale ◽  
Light Availability ◽  
Sharp Decrease ◽  
Dry Weight ◽  
Good Alternative ◽  
Production Costs ◽  
Determining Factors ◽  
Weight Protein ◽  
Low Costs

Large-scale lab culture of Ankistrodesmus gracilis and Diaphanososma birgei were evaluated by studying the biology and biochemical composition of the species and production costs. Ankistrodesmus gracilis presented exponential growth until the 6th day, with approximately 144 x 10(4) cells.mL-1, followed by a sharp decrease to 90 x 10(4) cells.mL-1 (8th day). Algae cells tended to increase again from the 11th day and reached a maximum of 135 x 10(4) cells.mL-1 on the 17th day. D. birgei culture showed exponential growth until the 9th day with 140 x 10² individuals.L-1, and increased again as from the 12th day. Algae A. gracilis and zooplankton D. birgei contain 47 to 70% dry weight protein and over 5% dry weight carbohydrates. The most expensive items in the context of variable costs were labor and electricity. Data suggested that temperature, nutrients, light availability and culture management were determining factors on productivity. Results indicate that NPK (20-5-20) may be used directly as a good alternative for mass cultivation when low costs are taken into account, promoting adequate growth and nutritional value for cultured A. gracilis and D. birgei.

Fine structure in the red algae - II. The structure of the cell wall of Rhodymenia Palmata

1959 ◽  
Vol 150 (941) ◽  
pp. 447-455 ◽  
Keyword(s):  
Cell Wall ◽  
Chemical Treatment ◽  
Amorphous Matrix ◽  
Dry Weight ◽  
Wall Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Floridean Starch ◽  
Thin Sectioning ◽  
Paper Chromatographic Separation

The cell-wall structure of the red alga Rhodymenia palmata has been examined by the methods of X -ray diffraction analysis and electron microscopy, including ultra-thin sectioning. The cell wall is shown to consist of numerous lamellae each of which is made up of unoriented, crystalline microfibrils embedded in an amorphous matrix of other cell-wall constituents. The material can be stretched reversibly up to 100% when wet, and the stretching induces orientation of the microfibrils. The ‘∝ cellulose' fraction, which accounts for only 2 to 7 % of the original dry weight, was isolated chemically and was analyzed by means of hydrolysis and paper chromatographic separation of the resulting sugars, and it was found to be composed of approximately equal quantities of glucose and xylose residues. Chemical treatment of the cell wall was found to cause considerable variations in the X -ray diagrams, which are discussed. It is concluded that the microfibrils contain both glucose and xylose residues in approximately equal proportions and that chemical treatment in this case causes changes in crystallinity of the structural component of the wall. The importance of these findings for the meaning of the term cellulose is discussed. The X -ray diagram of older fronds was found to be complicated by the occurrence of extra rings due to the presence of floridean starch, and the highly elastic properties of the thallus enabled the diagrams of the starch and the cell wall to be separated.

Metabolism of Food Reserves in Germinating Velvetleaf

Weed Science ◽  
1970 ◽  
Vol 18 (5) ◽  
pp. 565-571
Author(s):  
J. A. Mulliken ◽  
C. A. Kust ◽  
L. E. Schrader
Keyword(s):  
Hydrogen Cyanide ◽  
Isocitrate Lyase ◽  
Dry Weight ◽  
Maximal Activity ◽  
Radicle Growth ◽  
Fat Mobilization ◽  
Lyase Activity ◽  
Radicle Emergence ◽  
Weight Protein ◽  
Food Reserves

Endosperm dry weight, protein, and fat losses accompanied rapid radicle growth of velvetleaf (Abutilon theophrasti Medic.) between 12 and 36 hr of germination at 31 C. Cotyledonary reserves were mobilized after 36 hr. Isocitrate lyase activity sedimented with a particulate fraction in varying degrees, but maximal activity developed at times coincident with fat mobilization. Respiration of excised endosperms reached maximal rates shortly after radicle emergence. The actions of hydrogen cyanide, carbon monoxide, and 2,4-dinitrolphenol indicated that respiration of endosperms excised from imbibed and germinated seed was due to cytochrome oxidase activity, and was coupled to phosphorylation.

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