Development of helicoidal texture in the prerelease mucilage of quince (Cydonia oblonga) seed epidermis

1988 ◽  
Vol 66 (3) ◽  
pp. 460-467 ◽  
Author(s):  
R. M. Abeysekera ◽  
J. H. M. Willison
Keyword(s):  
Central Region ◽  
Liquid Crystalline ◽  
Amorphous Material ◽  
Epidermal Cells ◽  
Cydonia Oblonga ◽  
Thin Walled ◽  
Seed Epidermis ◽  
Developmental Phases ◽  
Transitional Phase ◽  
Helicoidal Texture

Quince (Cydonia oblonga Mill.) seed epidermis was examined cytologically during its development. Three developmental phases were delimited: immaturity, transition to maturity, and maturity. These cytological phases corresponded with phases of competence to release hydrated mucilage on wetting, immature tissue being completely incompetent and mature tissue fully competent. Growing cells of immature tissue were vacuolate and thin walled. By contrast, protoplasts of nongrowing mature epidermal cells had contracted to a remnant and been replaced by periplasmic deposits. Within these deposits, surrounded by amorphous material, were massive arrays of widely spaced microfibrils arranged helicoidally. In the oldest sample examined, periplasmic material appeared to be spewing through the broken outer walls of some cells. The periplasmic material is interpreted to be prerelease mucilage, which progressively fills the periplasm during a brief transitional phase. It seems that amorphous periplasmic material is deposited initially and microfibrils later intermingle with it. At some stage during filling of the periplasm, the microfibrils begin to organize, ultimately becoming helicoidal. Orderliness seems to begin in the central region of the periplasmic pool, not at its edges. It is proposed that nucleation of liquid crystalline helicoidal arrays occurs in the periplasm and that these arrays remain fluid until their disintegration during release as a result of hydration.

TELIOSPORE DEVELOPMENT IN THE PUCCINIASTREAE

1933 ◽  
Vol 9 (5) ◽  
pp. 458-485 ◽  
Author(s):  
S. M. Pady
Keyword(s):  
Epidermal Cells ◽  
The Other ◽  
General Situation ◽  
Thin Walled ◽  
Primordial Cell ◽  
Teliospore Development

The genera that constitute the Pucciniastreae display a wide variation in the type of teliospore produced, as well as in the time and place of production. From the standpoint of development, however, there is a general situation that is common. In all genera primordial cells are formed from enlarged hyphal cells of the mycelium. These give rise to teliospore initials which are in the epidermal cells in Calyptospora, Milesia, Hyalopsora and Thecopsora, and are subepidermal in the other genera. These initials divide to form the mature teliospores, which are thick or thin walled, and few to many-celled. In all cases the teliospore is the product of a single primordial cell.The teliospores of Calyptospora goeppertiana are formed from a perennial mycelium, which causes a witches' broom and hypertrophied stems on species of Vaccinium. The mycelium gives rise to primordial cells in the cortex just below the epidermis. Each primordial cell pierces the host wall above and the contents pass in to form the initial, which by growth and division becomes the teliospore. The mature teliospores are one- to four-celled, with a thickened, dark brown wall. Development is not simultaneous, but progressive, and the teliospores are first formed in the basal parts, moving slowly upward until every cell of the hypertrophied portion of the stem is completely filled. In four species of Milesia the method of development is similar. The spores, however, are thin walled, and are formed in the epidermal cells of the overwintered fronds of their fern hosts. Thecopsora vacciniorum is similar to Milesia in many respects. The teliospores are intra-epidermal, thin walled and multicellular. In Pucciniastrum the teliospores are subepidermal, and arise from primordial cells, as in Calyptospora, Milesia and Thecopsora. The teliospore initials are closely packed, and the mature spores may form extended crusts. The simplest type of development is found in Uredinopsis, which is generally considered to be the most primitive of the fern rusts. Primordial cells are formed in the same way as in the other genera. These round up to form the initials, and cross walls are laid down to give the mature spores.From these studies two possible lines of development are suggested, both beginning with Uredinopsis. One line would lead through the intra-epidermal forms, as Milesia, Calyptospora, etc., and the other through the subepidermal genera, as Pucciniastrum and Melampsoridium.

Papilla response of barley epidermal cells caused by Erysiphe graminis: rate and method of deposition determined by microcinematography and transmission electron microscopy

1979 ◽  
Vol 57 (8) ◽  
pp. 898-913 ◽  
Author(s):  
Richard J. Zeyen ◽  
W. R. Bushnel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Material ◽  
Time Lapse ◽  
Epidermal Cells ◽  
Erysiphe Graminis ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Wall Appositions ◽  
Entire Sequence

Papillae were deposited in barley epidermal cells directly beneath appressoria of Erysiphe graminis f. sp. hordei and appeared as hemispherical, internal wall appositions. The papilla response began shortly after the formation of a rapidly moving cytoplasmic aggregate beneath the appressorium. As documented in coleoptile tissue by time-lapse light microcinematography, the papillae grew rapidly for 20–30 min after becoming visible, their radii increasing by 0.1 μm/min. For small papillae, deposition continued for about 30 min; for larger papillae, deposition continued for 120–180 min. Results with transmission electron microscopy on leaf epidermal cells suggested that papilla deposition by host cytoplasmic aggregates can be divided into four sequential stages: (i) the deposition of osmiophilic (lipidic) materials, (ii) the deposition and partial compaction of nonosmiophilic, amorphous material (probably insoluble polysaccharides), (iii) compaction of nonosmiophilic, amorphous material, and (iv) the incorporation of osmiophilic material into the host wall and into the compacted nonosmiophilic, amorphous material. At maturity, the papillae are hardened, electron-opaque wall appositions that may be effective in preventing fungal penetration and development. Failure of papillae to prevent fungal penetration and development may be related to the inability of the epidermal cells to complete the entire sequence of events in papilla deposition before attempted fungal penetration.

The effect of ingested benzoylphenylurea on the ultrastructure of the cuticle deposited during the last larval instar of Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae)

1987 ◽  
Vol 65 (11) ◽  
pp. 2715-2723 ◽  
Author(s):  
Jean Percy-Cunningham ◽  
Diane Nicholson ◽  
Arthur Retnakaran
Keyword(s):  
Choristoneura Fumiferana ◽  
Larval Instar ◽  
Amorphous Material ◽  
Spruce Budworm ◽  
Amino Sugar ◽  
Epidermal Cells ◽  
Protein Component ◽  
Ultrastructural Changes ◽  
Sublethal Dose

The sequential ultrastructural changes induced by the ingestion of a sublethal dose of a benzoylphenylurea, chlorfluazuron, were investigated in sixth-instar larvae of the spruce budworm, Choristoneura fumiferana. The 4-day-old, postecdysis larvae showed the most profound ultrastructural effects. The newly formed endocuticle showed an absence of lamellae, indicating the lack of formation of chitin microfibrils. Vacuolated and fibrous areas containing an amorphous material, possibly proteinaceous, were observed in the region where lamellae would normally be present. The epidermal cells had microvilli with swollen and rounded tips. These cells also contained oval vesicles containing granular amorphous material. The in vivo inhibition of chitin deposition by this benzoylphenylurea was readily apparent. It is suggested that the amorphous material observed in the zone where chitin was lacking is the protein component of the glycoprotein chitin. It is possible that the benzoylphenylurea inhibits the assembly of the amino sugar with the protein to form microfibrils.

The liquid crystalline nature of the cytoskeleton in epidermal cells of the chaetognath Sagitta

1984 ◽  
Vol 16 (3) ◽  
pp. 469-481 ◽  
Author(s):  
Michel Duvert ◽  
Yves Bouligand ◽  
Christiane Salat
Keyword(s):  
Liquid Crystalline ◽  
Epidermal Cells ◽  
Crystalline Nature

On the Buckling of Thin Walled Tubes Under Axial Impact

1964 ◽  
Vol 68 (642) ◽  
pp. 418-419 ◽  
Author(s):  
R. C. Redwood
Keyword(s):  
Central Region ◽  
Short Wavelength ◽  
Large Scale ◽  
Axial Impact ◽  
Low Speed ◽  
Impact Tests ◽  
High Speeds ◽  
Thin Walled ◽  
Low Speeds ◽  
The Impact

In some recent impact tests in which thin walled square tubes were loaded axially to produce large scale buckling of the walls, a difference occurred between the behaviour at high speeds and that at low speeds. The tubes, standing on an anvil, were struck by a falling steel tup which was guided to strike the tubes approximately axially. At the higher speeds damage was confined to the impact end of the tube, with a short wavelength buckle adjacent to the end and longer waves farther from the end. At lower speeds damage occurred at either end, or, jn many cases, in the central region of the tube. The wavelengths in these low speed tests were longer than those occurring at high speeds. These two types of behaviour are illustrated on Fig. 1.

ROS accumulation in cotton ovule epidermal cells is necessary for fiber initiation

2013 ◽  
Author(s):  
mingxiong pang ◽  
Nickolas Sanford ◽  
Thea Wilkins
Keyword(s):  
Epidermal Cells ◽  
Cotton Leaf ◽  
Fiber Initiation ◽  
Leaf Trichomes ◽  
H2o2 Accumulation ◽  
Ros Accumulation ◽  
Cotton Ovule ◽  
Seed Epidermis ◽  
Leaf Trichome

Cotton (Gossypium hirsutum) fiber, an extremely elongated and thickened single cell of the seed epidermis, is the world’s most important natural and economical textile fiber. Unlike Arabidopsis leaf trichomes, fiber initials are randomly developed and frequently form in adjacent seed epidermal cells and follow no apparent pattern. Numerous publications suggested cotton fiber development shares a similar mechanism with Arabidopsis leaf trichome development. Here we show that H2O2 accumulation in cotton ovule epidermal cells by NBT staining ovules at different development stages between TM1 and N1n2, a lintless-fuzzless doubled mutant originated from TM1. In contrast, Arabidopsis and cotton leaf trichomes do not show H2O2 content. By adding DPI (H2O2 inhibitor) and SHAM (H2O2 activator) in vitro ovule cultures, we show fiber initiation directly involves with H2O2 accumulation. We propose that the directional accumulation of H2O2 in cotton ovule epidermal cell is the drive for fiber initiation, elongation.

scholarly journals THE STRUCTURE OF THE CENTRAL REGION IN THE SYNAPTONEMAL COMPLEXES OF HAMSTER AND CRICKET SPERMATOCYTES

1973 ◽  
Vol 56 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Alberto J. Solari ◽  
Montrose J. Moses
Keyword(s):  
Synaptonemal Complex ◽  
Central Region ◽  
Essential Role ◽  
Amorphous Material ◽  
Central Element ◽  
House Cricket ◽  
Widespread Occurrence ◽  
Whole Mount ◽  
Additional Protein ◽  
Surface Spreading

The fine structure of bivalents from golden hamster and house cricket spermatocytes has been studied with a whole mount surface-spreading method combined with negative staining. The elements of the synaptonemal complex show detail of structure which is absent in other preparative procedures. The transverse filaments found in the central region of the synaptonemal complex from both species are straight and have a similar width, 1 6–1 8 nm These filaments occur mainly in bundles The central element differs in architecture in the two species In hamster bivalents it is formed of longitudinal stretches of filaments 1.6–1 8 nm wide and a small amount of an amorphous material similar to that of the lateral elements In the cricket, the central element contains transverse fibrils which are continuous with the transverse filaments of the central region, and an amorphous material lying mainly along the sides of the central element All of the components of the central region of the synaptonemal complex are resistant to pancreatic DNase. The overlapping ends of the transverse filaments, together with additional protein material, make up the central element The widespread occurrence and close morphological and histochemical interspecies similarities of the transverse filaments indicate that they serve an essential role, probably one concerned with holding synapsed bivalents together via the lateral elements. Restrictions placed by the observations reported here on current models of the synaptonemal complex are discussed.

A light and electron microscope study of the structure of Protopterus annectens epidermis. I. Mucus production

1968 ◽  
Vol 46 (4) ◽  
pp. 767-772 ◽  
Author(s):  
Sonja M. Kitzan ◽  
Phillip R. Sweeny
Keyword(s):  
Plasma Membrane ◽  
Electron Microscope ◽  
Light Microscope ◽  
Amorphous Material ◽  
Middle Layer ◽  
Goblet Cells ◽  
Epidermal Cells ◽  
Staining Reaction ◽  
Mucus Production ◽  
Protopterus Annectens

The structure of the epidermis of Protopterus annectens is described from light microscope and electron microscope observation with emphasis on mucus production. The epidermis contains a great number of goblet cells which are PAS-positive to varying degrees. Based on the difference in staining reaction the goblet cells are divided into three types (I, II, and III). Also PAS-positive is a narrow zone of cytoplasm below the plasma membrane of the surface epidermal cells. In the material prepared for the electron microscope the goblet cells are found to be of three types (A, B, and C) classified according to the size and electron opacity of the mucus droplets. Epidermal cells of the upper middle layer begin to show a division into two distinct cytoplasmic zones with the appearance of new organelles, particularly in the perinuclear zone. The cytoplasmic zonation is more pronounced in the surface cell layer and vesicles filled with amorphous material (first noticed in the upper middle layer) are concentrated below the surface plasma membrane. Light microscope and electron microscope results are correlated and it is concluded that all epidermally derived cells at some time become involved in mucus production.

Cell wall thickness and cell dimensions in plant parts of eight forage species

1998 ◽  
Vol 131 (1) ◽  
pp. 59-67 ◽  
Author(s):  
P. REZVANI MOGHADDAM ◽  
D. WILMAN
Keyword(s):  
Festuca Arundinacea ◽  
Cell Walls ◽  
Structural Integrity ◽  
Epidermal Cells ◽  
Cross Sectional ◽  
Plant Parts ◽  
Cell Dimensions ◽  
Chloris Gayana ◽  
Thin Walled ◽  
Different Parts

To appreciate more clearly some of the physical characteristics of forages which may be important in relation to digestibility and structural integrity, different parts of eight plant species were examined for the proportion of thick-walled, thin-walled and epidermal cells, the thickness of the cell walls and the diameter, length and volume of the cells. The eight species were: Trifolium repens L., Medicago sativa L., Desmodium intortum (Mill.) Urb., Lolium perenne L., Festuca arundinacea Schreb., Chloris gayana Kunth, Cenchrus ciliaris L. and Zea mays L. Early harvesting was compared with later harvesting in each of two years. The plants were grown in a heated glasshouse in spring–summer.The plant parts with the lowest proportion of thick-walled cells (3–6% of cross-sectional area) were the legume leaflets and those with the highest proportion (47–57%) were the leaf blades and stems of C. ciliaris. The plant parts with the highest proportion of thin-walled cells were the legume leaflets and petioles and the Z. mays stems and leaf sheaths. The walls of the cells categorized as thick-walled were thinnest (0·9 μm) in L. perenne leaf blades and T. repens leaflets and thickest (2·0–2·3 μm) in the leaf blade midribs, leaf sheaths and stems of Z. mays and in the stems and petioles of T. repens. The thinnest outer walls of epidermal cells (0·9 μm) were recorded for the leaf blades of L. perenne.The largest cells within the categories and plant parts examined (1 100000 μm3) were thin-walled cells in the stems of Z. mays. The longest cells recorded (180 μm) were thin-walled cells in the petioles of T. repens. The thick-walled cells were particularly small (1800–2600 μm3) in L. perenne leaf blades and sheaths and in T. repens leaflets. The largest thick-walled cells in the study were in the stems and petioles of T. repens. The epidermal cells of D. intortum leaflets, petioles and stems were particularly small (2000–3000 μm3).

Studies in the genus Riccia (Marchantiales) from southern Africa. 3. R. schelpei, a new species, in the new subgenus Chartacea

Bothalia ◽  
1986 ◽  
Vol 16 (1) ◽  
pp. 29-33
Author(s):  
O. H. Volk ◽  
S. M. Perold
Keyword(s):  
New Species ◽  
Southern Africa ◽  
Epidermal Cells ◽  
Western Cape ◽  
New Subgenus ◽  
Thin Walled ◽  
A New Species

Riccia schelpei Volk Perold, sp. nov., endemic to the western Cape, is described. It is characterized by the parchment-like epidermis of the thallus, thick-walled hyaline epidermal cells and by dorsal air-pores encircled by a raised ring of smaller thin-walled cells. This species is the type of the new monotypic subgenus Chartacea Perold.

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