A crystalline inclusion in sieve element nuclei of Amsinckia. I. The inclusion in differentiating cells

1979 ◽  
Vol 38 (1) ◽  
pp. 1-10
Author(s):  
K. Esau ◽  
A.C. Magyarosy
Keyword(s):  
Sieve Element ◽  
Entire Length ◽  
The Other ◽  
Crystalline Inclusion ◽  
Sieve Elements

The presence of usually single, elongated, compound crystalloids in nuclei of sieve elements is an outstanding characteristic of the phloem of Amsinckia douglasiana A. DC. (Boraginaceae). The crystalloid consists of two components forming alternating panels, or blocks, that extend through the entire length of the crystalloid and radiate from the centre where one of the components predominates. Three to seven panels for each component were recorded. One component consists of 4-sided tubules closely packed in highly ordered aggregates, the other of wider 6-sided tubules rather loosely arranged in paracrystalline aggregates. The crystalloid arises at the beginning of sieve element differentiation. Aggregates of 4-sided tubules appear first. In plants infected with the curly top virus, the crystalloids do not differ from those in non-infected controls in structure and conformation. But because the phloem in infected plants is hyperplastic, with most of the cells differentiating as sieve elements, the crystalloids are far more abundant in diseased than in healthy plants.

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.

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.

Vascular system of the floret of Alopecurus carolinianus (Gramineae)

1987 ◽  
Vol 65 (12) ◽  
pp. 2592-2600 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Sieve Tube ◽  
Sieve Element ◽  
Sieve Elements

The interconnecting vascular system of the floret of Alopecurus carolinianus Walter begins as a single, collateral bundle, which enters the rachilla and becomes reorganized into a diarch pattern while ascending between the glumes. During a pronounced posterior enlargement, the rachilla bundle becomes connected with the median and four lateral bundles of the lemma. Above the trace to the lemma median, elements of a xylem discontinuity surrounded by those of a sieve-element plexus form in the rachilla bundle. Higher, a trace consisting of elements of the xylem discontinuity and the plexus enters the anterior and the posterior stamen. Two bundles, the lowest portion of the pistil vasculature, rise eccentrically from the xylem discontinuity and sieve-element plexus at the level of the stamen traces. The bundles condense into one which rotates counterclockwise and connects with the anterior sieve tube of the pistil. The xylem discontinuity of the bundle now in the pistil begins to diminish, and the sieve elements fan out to the sides and posterior of the xylem discontinuity. From the sieve elements one or two posterolaterals emerge toward the styles. The bundle of diffuse sieve elements in a semicircle behind the diminishing xylem discontinuity is now the placental bundle of the pistil. After its xylem discontinuity and then its sieve elements fade out, the placental bundle merges with the ovule at the chalaza.

A Contribution to the Knowledge of the Bot-flies, Gastrophilus intestinalis, DeG., G. haemorrhoidalis, L., and G. nasalis, L.

1918 ◽  
Vol 9 (2) ◽  
pp. 91-106 ◽  
Author(s):  
S. Hadwen ◽  
A. E. Cameron
Keyword(s):  
The Body ◽  
Entire Length ◽  
Equal Length ◽  
The Other ◽  
Brownish Black

The eggs of the three species of bot-flies discussed in this paper are distinguished by the fact of that of G. haemorrhoidalis being the only one stalked. It is also longer than those of the other two species, which are of about equal length. Further, it is brownish black in colour, that of G. intestinalis being whitish yellow and G. nasalis yellow. The egg of G. intestinalis adheres to the hair by clasping flanges, which run only two-thirds of its length, whilst the flanges of the G. nasalis egg run almost the entire length.The egg of G. haemorrhoidalis is not inserted nor screwed into the skin of the host. The eggs of G. intestinalis are laid indiscriminately on the body of the host, but preferably on the long hairs investing the inside of the foreleg. G. nasalis lays its eggs on the hairs of the intermaxillary space, and G. haemorrhoidalis on the hairs of the lips, preferably the lower.

scholarly journals II.—Circular Magnetisations accompanying Axial and Sectional Currents along Iron Tubes

1895 ◽  
Vol 37 (1) ◽  
pp. 7-16
Author(s):  
Cargill G. Knott
Keyword(s):  
Magnetic Induction ◽  
Entire Length ◽  
The Other ◽  
External Diameter ◽  
Diameter Measurement ◽  
Current Passing ◽  
The Mean ◽  
Iron Tube ◽  
Different Diameters ◽  
A Current

The experiments now to be described have for their object the investigation of the magnetic induction in an iron conductor under the influence of a current passing through it. The method of experiment was briefly in this wise. An iron tube was magnetised circularly by a current passed from end to end along its entire length; and the induction so produced in the iron was measured in terms of the current induced in a coil of wire wound longitudinally round the walls of the tube.In the experiments four tubes were used, all of the same length and nearly the same external diameter. The internal diameters of one pair were approximately double those of the other. The various dimensions are given accurately in the following table, the tubes being distinguished as A, B, a, b. Each diameter measurement is the mean of eight measurements taken across different diameters.

Anatomy and ultrastructure of the endophytic system of Pilostyles thurberi (Rafflesiaceae)

1985 ◽  
Vol 63 (7) ◽  
pp. 1231-1240 ◽  
Author(s):  
Job Kuijt ◽  
D. Bray ◽  
A. R. Olson
Keyword(s):  
Cell Types ◽  
Sieve Element ◽  
Cell Type ◽  
Discontinuous System ◽  
Sieve Elements ◽  
The Third ◽  
Sieve Plates ◽  
Host Parasite ◽  
Anatomy And Ultrastructure ◽  
Sieve Pores

The endophytic system of Pilostyles thurberi Gray consists of initially uniseriate filaments which develop into an anastomosing complex of larger cortical strands and radial sinkers. In the cortical strands three cell types are recognized, two of which differ largely in the density of the cytoplasm, the shape of the nucleus, and the degree to which the cytoplasm becomes plasmolyzed during fixation. The nuclei of both cell types contain two nucleoli which are physically connected by a nucleolar bridge. The third cell type demonstrates sieve plates, including a calloselike substance in the sieve pores and is consequently considered to be a sieve element. The sieve elements appear to form a discontinuous system and are regarded as a vestigial cell type. Plasmodesmal connections across the host–parasite interface have not been observed.

Fine structure of the phloem of Pisum sativum. I. The sieve element ontogeny

1965 ◽  
Vol 13 (2) ◽  
pp. 171 ◽  
Author(s):  
MC Wark ◽  
TC Chambers
Keyword(s):  
Endoplasmic Reticulum ◽  
Pisum Sativum ◽  
Nuclear Material ◽  
Sieve Element ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Pisum Sativum L ◽  
Ontogenetic Study ◽  
Sieve Plates ◽  
Peripheral Cytoplasm

An ontogenetic study of secondary phloem sieve elements of Pisum sativum L., fixed on the intact plant for electron microscopy, indicates that the connecting strands across the sieve plates are continuities of the endoplasmic reticulum. Each connecting strand is surrounded by a callose cylinder. The peripheral cytoplasm of the nucleate "young" sieve elements contains longitudinally oriented tubules of endoplasmic reticulum. As the sieve elements develop, nuclear material is extruded into the cytoplasm by way of a fibrotubular body which is structurally distinct from the slime body. When the cells are fully expanded the slime bodies disperse. This process is followed by breakdown of a number of organelles including the nucleus and tonoplast. This apparently leaves the endoplasmic reticulum free in the cell lumen.

Fine structure of the primary root phloem of Pisum

1968 ◽  
Vol 16 (1) ◽  
pp. 37 ◽  
Author(s):  
SY Zee ◽  
TC Chambers
Keyword(s):  
Primary Root ◽  
Root Apex ◽  
Sieve Element ◽  
Cross Wall ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Pisum Sativum L ◽  
Companion Cells ◽  
Stem Internode

The morphogenesis of the sieve elements, companion cells, and phloem parenchyma in the region between 0.5 and 2.0 mm from the actively growing root apex of seedlings of Pisum sativum L. cv. Telephone is described. The overall developmental pattern is essentially similar to that already described for the secondary phloem of the young stem internode of the same species, although differences in the development of some organelles do exist between the two types of phloem. The development of the sieve element is traced from the earliest stages of cross wall formation up to the morphologically mature stages. Very few sieve elements reach morphological maturity in this region. The possibility that the functional translocatory sieve elements are those at earlier stages of development is discussed.

Varieties of English in the urban landscapes of Hong Kong and Shenzhen

English Today ◽  
2014 ◽  
Vol 30 (3) ◽  
pp. 22-32 ◽  
Author(s):  
Anna Danielewicz-Betz ◽  
David Graddol
Keyword(s):  
Hong Kong ◽  
Urban Development ◽  
Mainland China ◽  
Entire Length ◽  
The Other ◽  
Modern China ◽  
Urban Landscapes ◽  
Special Administrative Region ◽  
Mainland Chinese ◽  
Chinese City

The border between mainland China and Hong Kong has become one of the world's most fascinating linguistic divides. On one side lies the mainland Chinese city of Shenzhen, stretching the entire length of the border – an extraordinary urban development which in many ways epitomises the recent urbanisation of modern China. On the other side lies the Special Administrative Region (SAR) of Hong Kong (see Figure 1). It is not possible to cross from Hong Kong to mainland China by land without passing through one of the Shenzhen checkpoints.

scholarly journals Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

2013 ◽  
Vol 9 ◽  
pp. 106-117 ◽  
Author(s):  
Dyanne L Cruickshank ◽  
Natalia M Rougier ◽  
Raquel V Vico ◽  
Susan A Bourne ◽  
Elba I Buján ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
The Other ◽  
Hydrolysis Rate ◽  
Crystalline Inclusion ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Host Compound ◽  
Hydrolysis Of ◽  
Remarkable Reduction

An anhydrous 1:1 crystalline inclusion complex between the organophosphorus insecticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate] and the host compound heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) was prepared and its structure elucidated by single-crystal X-ray diffraction. This revealed two independent host molecules in the asymmetric unit. In one of these, the cavity is occupied by two disordered guest components (distinguishable as rotamers with respect to the P–OAr bond) while in the other, three distinct guest components with site-occupancies 0.44, 0.29 and 0.27 appear, the last having a reversed orientation relative to all the other components. Kinetic studies of the alkaline hydrolysis of fenitrothion in the presence of DIMEB showed a remarkable reduction of 84% in the rate of this reaction relative to that for the free substrate, a value exceeding those previously attained with the native hosts, β- and γ-cyclodextrin, and fully methylated β-cyclodextrin.

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