Nuclear Crystalloids in Sieve Elements of Species of Echium (Boraginaceae)

1982 ◽  
Vol 54 (1) ◽  
pp. 149-160
Author(s):  
KATHERINE ESAU ◽  
JENNIFER THORSCH
Keyword(s):  
Protein A ◽  
Sieve Element ◽  
Crystalline Form ◽  
Two Dimensional ◽  
Common Component ◽  
Dimensional Lattice ◽  
Sieve Elements ◽  
Ultrastructural Studies ◽  
P Protein ◽  
Systematic Character

Ultrastructural studies of differentiating phloem of the midvein in 15 species of Echium (Boraginaceae) have shown that in every species one or more crystalloids develop in sieve-element nuclei. These inclusions appear as soon as the cell begins to differentiate from a procambial derivative. Small at first, they enlarge later, particularly in length. The crystalloid may extend end-to-end in the correspondingly elongated nucleus. When the nucleus disintegrates in the maturing cell the crystalloid is released into the cell lumen where it remains intact or becomes fractured into large pieces. No dissociation into subunits was observed. The crystalloids are composed of tightly packed narrow rods (tubules) forming a two-dimensional lattice of squares in transections and a system of parallel striations in longitudinal sections. The similarities of these inclusions to the crystalline form of P-protein in Fabaceae raises the question of terminological delimitation of P-protein, a common component of angiospermous sieve-element protoplasts. The occurrence of nuclear crystalloids in another previously investigated genus in the Boraginaceae, Amsinckia, suggests that this inclusion should be explored in boraginaceous representatives for its possible value as a systematic character.

scholarly journals A crystalline inclusion in sieve element nuclei of Amsinckia. II. The inclusion in maturing cells

1979 ◽  
Vol 38 (1) ◽  
pp. 11-22
Author(s):  
K. Esau ◽  
A.C. Magyarosy
Keyword(s):  
Hydrostatic Pressure ◽  
Sieve Element ◽  
Crystalline Inclusion ◽  
Sieve Elements ◽  
P Protein ◽  
Sudden Release ◽  
Sieve Plates ◽  
Tubular Components

The compounds crystalloids formed in sieve element nuclei of Amsinckia douglasiana A. DC. (Boraginaceae) during differentiation of the cell become disaggregated during the nuclear breakdown characteristic of a maturing sieve element. The phenomenon occurs in both healthy and virus-infected plants. The crystalloid component termed cy, which is loosely aggregated, separates from the densely aggregated component termed cx and disperses. The cx component may become fragmented, or broken into large pieces, or remain intact after the cell matures. After their release from the nucleus both crystalloid components become spatially associated with the dispersed P-protein originating in the cytoplasm, but remain distinguishable from it. The component tubules of P-protein are hexagonal in transections and are somewhat wider than the 6-sided cy tubules. The cx tubules are much narrower than the P-protein or the cy tubules and have square transections. Both the P-protein and the products of disintegrated crystalloids accumulate at sieve plates in sieve elements subjected to sudden release of hydrostatic pressure by cutting the phloem. The question of categorizing the tubular components of the nuclear crystalloid of a sieve element with reference to the concept of P-protein is discussed.

scholarly journals TUBULAR AND FIBRILLAR COMPONENTS OF MATURE AND DIFFERENTIATING SIEVE ELEMENTS

1967 ◽  
Vol 34 (3) ◽  
pp. 801-815 ◽  
Author(s):  
James Cronshaw ◽  
Katherine Esau
Keyword(s):  
Light And Electron Microscopy ◽  
Protein Body ◽  
Sieve Element ◽  
Protein Component ◽  
Sieve Plate ◽  
Sieve Elements ◽  
P Protein ◽  
Ontogenetic Study ◽  
P2 Protein ◽  
Fibrillar Component

An ontogenetic study of the sieve element protoplast of Nicotiana tabacum L. by light and electron microscopy has shown that the P-protein component (slime) arises as small groups of tubules in the cytoplasm. These subsequently enlarge to form comparatively large compact masses of 231 ± 2.5 (SE)A (n = 121) tubules, the P-protein bodies. During subsequent differentiation of the sieve element, the P-protein body disaggregates and the tubules become dispersed throughout the cell. This disaggregation occurs at about the same stage of differentiation of the sieve elements as the breakdown of the tonoplast and nucleus. Later, the tubules of P-protein are reorganized into smaller striated 149 ± 4.5 (SE)A (n = 43) fibrils which are characteristic of the mature sieve elements. The tubular P-protein component has been designated P1-protein and the striated fibrillar component P2-protein. In fixed material, the sieve-plate pores of mature sieve elements are filled with proteinaceous material which frays out into the cytoplasm as striated fibrils of P2-protein. Our observations are compatible with the view that the contents of contiguous mature sieve elements, including the P-protein, are continuous through the sieve-plate pores and that fixing solutions denature the proteins in the pores. They are converted into the electron-opaque material filling the pores.

Inclusions in nuclei and plastids of Boraginaceae and their possible taxonomic significance

1989 ◽  
Vol 67 (12) ◽  
pp. 3608-3617 ◽  
Author(s):  
Deborah D. Fisher ◽  
Jennifer Thorsch ◽  
Katherine Esau
Keyword(s):  
Proteolytic Enzyme ◽  
Ultrastructural Level ◽  
Sieve Element ◽  
Nuclear Inclusions ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
The Family ◽  
Parenchyma Cells ◽  
Parallel Arrangement ◽  
Systematic Character

A survey of 68 species representing 28 genera in the family Boraginaceae was conducted at the ultrastructural level to determine presence of nuclear crystalloids in sieve elements and occurrence of crystalline structures in chloroplasts of phloem parenchyma cells. Nuclear crystalloids were identified in 55 of the species examined, and 25 of the species contained chloroplast crystals. The nuclear crystals were mainly composed of thin rods densely packed in parallel arrangement. Their sizes, shapes, and numbers varied, but they were basically prismatic or possibly cubical. During maturation, the sieve element nuclei disintegrated and the crystalloids were released into the cell lumen where they remained intact. Loosely arranged paracrystalline components associated with the dense nuclear crystalloids were found only in the genus Amsinckia. Crystalline inclusions in the parenchyma chloroplasts were made up of fibers loosely aligned in a herringbone pattern. The lability of the chloroplast crystals to the proteolytic enzyme, protease, was tested on 10 species, and only Onosma stellulatum Waldst. & Kit. chloroplast crystals were routinely digested. The high percentage of nuclear crystalloids found in this family suggests that these inclusions could be valuable as a systematic character. Key words: sieve elements, nuclear inclusions, plastid crystals, Boraginaceae.

Protein Component in Sieve Elements of Quercus Rubra L.

1976 ◽  
Vol 34 ◽  
pp. 40-41
Author(s):  
Lidija Murmanis
Keyword(s):  
Quercus Rubra ◽  
Sieve Element ◽  
Protein Component ◽  
Sieve Elements ◽  
P Protein ◽  
Intimate Association ◽  
Rough Er ◽  
Differentiation Stage ◽  
Oriented Parallel ◽  
Stage 1

At the earliest stage, P-protein in red oak sieve elements can be identified with the fine filaments embedded in the cytoplasm (Fig. 1), and they appear similar to the P-protein component in Cucurbita maxima at an early differentiation stage (1). At this time ribosomes (in a spiral configuration) and the rough ER are numerous and in intimate association with the filaments. As differentiation proceeds P-protein bodies are formed in which the filaments are randomly arranged (Fig. 2). Later the filaments become oriented parallel to one another (Fig. 1, at right) and are transformed structurally into tubules. Tubules aggregate into crystalline bodies (Figs. 3, 4) which resemble extruded nucleoli reported previously (2, 3). Individual tubules have a diameter of about 235A and a tripartite structure--60-70A thick electron-dense walls separated by an electron-transparent core. During the disintegration of sieve element protoplast the crystalline bodies disperse and tubules gradually change into fibrils.

Nuclear crystalloids in sieve elements of Boraginaceae: a protein digestion study

1983 ◽  
Vol 64 (1) ◽  
pp. 37-47
Author(s):  
J. Thorsch ◽  
K. Esau
Keyword(s):  
Proteolytic Enzymes ◽  
Differential Response ◽  
Sieve Element ◽  
Enzyme Digestion ◽  
The Other ◽  
Sieve Plate ◽  
Protein Digestion ◽  
Sieve Elements ◽  
P Protein ◽  
Parallel Arrangement

Nuclear crystalloids have been found in sieve elements of several Boraginaceae. Nuclei of differentiating sieve elements of Echium and other genera except Amsinckia contain one or more crystalloids composed of thin rods densely packed in parallel arrangement. After the nuclei disintegrate in the maturing sieve element the crystalloids are released into the cell lumen where they persist intact. In Amsinckia the crystalloid consists of two components: a dense component, similar to the crystalloid in the other genera and a loosely arranged paracrystalline component. The proteinaceous nature of the nuclear crystalloids and their possible similarity to P-protein was investigated by enzyme digestion techniques. Three proteolytic enzymes were employed in this study: protease, pepsin and trypsin. Successful digestion of the dense crystalloid in both Echium and Amsinckia was obtained with each enzyme tested. P-protein plugging the sieve plate pores was also digested. The loose component in Amsinckia and the aggregated and dispersed P-protein were not affected by the enzyme digestion procedures. These results seemed to indicate that the density or compactness of the proteinaceous inclusions may play a role in the differential response.

Chrysanthemum phloem necrosis: symptomatology and histopathology

1989 ◽  
Vol 67 (4) ◽  
pp. 1014-1023 ◽  
Author(s):  
R. J. McGovern ◽  
R. K. Horst ◽  
H. W. Israel
Keyword(s):  
Protein A ◽  
Chrysanthemum Morifolium ◽  
Cell Component ◽  
Sieve Elements ◽  
Cultivar Group ◽  
P Protein ◽  
Plate Elements ◽  
Phloem Necrosis ◽  
Chrysanthemum Morifolium Ramat ◽  
Mycoplasmalike Organisms

The symptomatology and histopathology of chrysanthemum phloem necrosis, a new disease of florists' chrysanthemum was investigated. The disease results in flecking, yellowing, and premature deterioration of lower leaves and flower distortion in the Dendranthema grandiflora Tzveler. (syns. D. morifolia Ramat., Chrysanthemum morifolium Ramat.) Marble cultivar group. Cleared leaves of 'Pink Marble' revealed vascular browning in midveins and secondary veins that was enhanced at 32 °C. The sieve elements and associated cells in affected leaves were often necrotic and collapsed, a condition that was aggravated by elevated temperature. Spherical-to-elongate mycoplasmalike organisms, 0.2–1.0 μm diameter, were observed only in infected plants within collapsed sieve elements. Mycoplasmalike organisms were not detected in uninfected plants; sieve-plate elements contained merely fibrillar p-protein, a normal cell component. In comparison to uninfected plants abnormal callose accumulation and lignin formation were observed in the phloem of infected plants, and elevated levels of phenolic materials were found in vascular and nonvascular tissues.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

scholarly journals DISCRETE AND CONTINUUM APPROACHES TO THREE-DIMENSIONAL QUANTUM GRAVITY

1991 ◽  
Vol 06 (39) ◽  
pp. 3591-3600 ◽  
Author(s):  
HIROSI OOGURI ◽  
NAOKI SASAKURA
Keyword(s):  
Gauge Theory ◽  
Moduli Space ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Analogue Model ◽  
Gauge Invariant ◽  
Invariant Functions ◽  
Dimensional Lattice ◽  
Chern Simons ◽  
Dimensional Surface

It is shown that, in the three-dimensional lattice gravity defined by Ponzano and Regge, the space of physical states is isomorphic to the space of gauge-invariant functions on the moduli space of flat SU(2) connections over a two-dimensional surface, which gives physical states in the ISO(3) Chern–Simons gauge theory. To prove this, we employ the q-analogue of this model defined by Turaev and Viro as a regularization to sum over states. A recent work by Turaev suggests that the q-analogue model itself may be related to an Euclidean gravity with a cosmological constant proportional to 1/k2, where q=e2πi/(k+2).

Nondispersive Protein Bodies in Sieve Elements: A Survey and Review of their Origin, Distribution and Taxonomic Significance

IAWA Journal ◽  
1991 ◽  
Vol 12 (2) ◽  
pp. 143-175 ◽  
Author(s):  
H.-Dietmar Behnke
Keyword(s):  
Electron Microscope ◽  
Protein Bodies ◽  
Evolutionary Trends ◽  
Taxonomic Significance ◽  
Additional Species ◽  
Sieve Elements ◽  
P Protein ◽  
Taxonomic Range ◽  
Characteristic Features

Nondispersive protein bodies present in the sieve elements in addition to dispersive P-protein are characteristic features of many woody dicotyledons; their origin may be nuclear or cytoplasmic. While nuclear nondispersive protein bodies are found in only two families, the Boraginaceae and Myristicaceae, bodies of cytoplasmic origin are present in 39 of the more than 350 families screened. These results were obtained from 228 dicotyledons studied with the electron microscope and data of additional species from the literature. The terminology, origin, form and distribution of nondispersive protein bodies are discussed. Their ultrastructural composition is described as being predominantly spindle-shaped, compound- spherical, rod-shaped and rosette-like. Based on the data accumulated from over 450 species (of about 3000 screened) it is evident that their taxonomic range is confined to a few dicotyledon superorders. Compound-spherical nondispersive protein bodies are characteristic of most of the Malvanae/Violanae; spindle-shaped forms are restricted to the Fabaceae (Rutanae). Rosanae-Proteanae-Myrtanae and the Magnolianae are the only other superorders that contain nondispersive protein bodies in several of their families. Evolutionary trends and possible taxonomic consequences implied in this distribution are discussed.

Sign in / Sign up

Export Citation Format

Share Document