scholarly journals Identification of sieve elements and companion cell protoplasts by a combination of brightfield and fluorescence microscopy

2018 ◽  
Vol 6 (9) ◽  
pp. e01179
Author(s):  
Prabhjot Kaur ◽  
Pedro Gonzalez ◽  
Manjul Dutt ◽  
Ed Etxeberria
Keyword(s):  
Fluorescence Microscopy ◽  
Companion Cell ◽  
Sieve Elements

Fine structure of the phloem of Pisum sativum. II. The companion cell and phloem parenchyma

1965 ◽  
Vol 13 (2) ◽  
pp. 185
Author(s):  
MC Wark
Keyword(s):  
Fine Structure ◽  
Sieve Element ◽  
Companion Cell ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Wall Structures ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Vacuolated Cells

The companion cells of the secondary phloem of Pisum contain all the organelles characteristic of cells possessing an active metabolism. The cytoplasm of the companion cells shows little change during ontogeny. Complex plasmodesmata connect the sieve elements and companion cells. These are the only connections observed between the sieve elements and other phloem cells. New wall structures of the companion cells are described. These structures are here tentatively called trabeculae; they intrude into the cytoplasm, but never completely cross the cell. The trabeculae alter in appearance at the time when the sieve element nucleus and tonoplast disappear. The phloem parenchyma cells are large vacuolated cells wider in diameter but shorter in length than the sieve elements. They contain all the organelles found in normal photosynthetic tissue. The cytoplasm of the phloem parenchyma shows little change during ontogeny. Plasmodesmata of well-developed pit fields connect the phloem parenchyma with the companion cells. The phloem parenchyma does not communicate with the sieve elements.

Occurrence of Sieve Elements in Phloem Rays

IAWA Journal ◽  
1997 ◽  
Vol 18 (2) ◽  
pp. 197-201 ◽  
Author(s):  
Kishore S. Rajput ◽  
K. S. Rao
Keyword(s):  
Azadirachta Indica ◽  
Tectona Grandis ◽  
Sieve Tube ◽  
Companion Cell ◽  
Secondary Phloem ◽  
Detailed Structure ◽  
Sieve Elements ◽  
P Protein ◽  
Or Groups ◽  
Sieve Plates

Solitary sieve elements or groups of sieve elements were encountered in the rays of secondary phloem of Erythrina indica, Guazuma tomentosa, Acacia nilotica, Azadirachta indica, and Tectona grandis trees. These elements were short and possessed simple and compound sieve plates on their transverse to slightly oblique end walls. Each sieve tube element was associated with a single companion cell at their comers. Like axial sieve tube elements, the sieve tube elements of the rays showed slime (P-protein) plugs and cytoplasmic strands when functional and massive deposition of callose on sieve plates in nonfunctional sieve tube elements. The distribution pattern of these ray sieve elements differed among the species studied. The detailed structure and possible significance of these elements are discussed.

Sieve element and companion cell: the story of the comatose patient and the hyperactive nurse

2000 ◽  
Vol 27 (6) ◽  
pp. 477 ◽  
Author(s):  
Aart J. E. van Bel ◽  
Michael Knoblauch
Keyword(s):  
Phloem Transport ◽  
Division Of Labour ◽  
Sieve Element ◽  
Companion Cell ◽  
Concerted Action ◽  
Sieve Elements ◽  
Cell Complexes ◽  
Photoassimilate Translocation ◽  
Companion Cells ◽  
Evolutionary Descent

Sieve elements and companion cells constitute the modules of the conducting elements in the phloem ofAngiosperms. Consequently, phloem transport basically relies on the concerted action of the sieve element/companion cell complexes. Sieve elements and companion cells are highly interactive units and show an extreme division of labour as exemplified by their state of life. Whereas the sieve element is almost ‘clinically’ dead, the companion cell is a paragon of bubbling activity. In the course of evolution, the sieve element has sacrificed all of its genetic and most of its metabolic equipment to serve photoassimilate translocation. A small part of the structural and metabolic outfit has been retained for a proper accomplishment of its function. In contrast, the cells bordering the sieve element have gained metabolic weight during evolution. With reference to their evolutionary descent, the peculiarities of sieve elements and companion cells are discussed in the light of recent cell-biological and molecular-biological findings. Emphasis is focused on their interaction, which is the secret of the success of the sieve element/companion cell complex.

Sieve element biology provides leads for research on phytoplasma lifestyle in plant hosts

2019 ◽  
Vol 70 (15) ◽  
pp. 3737-3755 ◽  
Author(s):  
Aart J E van Bel ◽  
Rita Musetti
Keyword(s):  
Cell Biology ◽  
Sieve Element ◽  
Companion Cell ◽  
Electron Microscopic ◽  
Sieve Elements ◽  
Cell Complexes ◽  
Companion Cells ◽  
Phytoplasma Infection ◽  
Sieve Tubes ◽  
Physical And Chemical

Abstract Phytoplasmas reside exclusively in sieve tubes, tubular arrays of sieve element–companion cell complexes. Hence, the cell biology of sieve elements may reveal (ultra)structural and functional conditions that are of significance for survival, propagation, colonization, and effector spread of phytoplasmas. Electron microscopic images suggest that sieve elements offer facilities for mobile and stationary stages in phytoplasma movement. Stationary stages may enable phytoplasmas to interact closely with diverse sieve element compartments. The unique, reduced sieve element outfit requires permanent support by companion cells. This notion implies a future focus on the molecular biology of companion cells to understand the sieve element–phytoplasma inter-relationship. Supply of macromolecules by companion cells is channelled via specialized symplasmic connections. Ca2+-mediated gating of symplasmic corridors is decisive for the communication within and beyond the sieve element–companion cell complex and for the dissemination of phytoplasma effectors. Thus, Ca2+ homeostasis, which affects sieve element Ca2+ signatures and induces a range of modifications, is a key issue during phytoplasma infection. The exceptional physical and chemical environment in sieve elements seems an essential, though not the only factor for phytoplasma survival.

Ultrastructural Aspects of Primary Phloem. Sieve Elements in Poinsettia (Euphorbia Pulcherrima. Euphorbiaceae)

IAWA Journal ◽  
1988 ◽  
Vol 9 (4) ◽  
pp. 363-373 ◽  
Author(s):  
Jennifer Thorsch ◽  
Katherine Esau
Keyword(s):  
Endoplasmic Reticulum ◽  
Leaf Blade ◽  
Protein Body ◽  
Developmental Changes ◽  
Euphorbia Pulcherrima ◽  
Companion Cell ◽  
Sieve Elements ◽  
P Protein ◽  
Companion Cells ◽  
Sieve Plates

Certain developmental changes of sieve elements in the primary phloem of Euphorbia pulcherrima Willd. ex Klotsch (Poinsettia) were examined in the leaf blade, petiole and young stem. The sieve elements have simple sieve plates and, as seen in transection, each is associated with a single companion cell . Since, as expected, our fixed material showed a deposition of callose in sieve plates and in the sieve areas joining the sieve elements with the companion cells, the course of development and distribution of this callose was recorded. The sieve elements contain two types of proteinaceous inclusions, both cytoplasmic in origin. One is the typical form of P-protein composed initially of tubular units; later, the tubules become striated fibrils by stretching. The second inclusion is a nondispersing protein body, the first distinct feature identifying the differentiating sieve elements as such. It persists during the differentiation of the cell and is present in mature sieve elements. Aggregated endoplasmic reticulum is rather sparse in sieve elements, but the typical stacked form is occasionally observed in mature cells.

Proteins in the sieve element-companion cell complexes: their detection, localization and possible functions

2000 ◽  
Vol 27 (6) ◽  
pp. 489 ◽  
Author(s):  
Hiroaki Hayashi ◽  
Akari Fukuda ◽  
Nobuo Suzui ◽  
Shu Fujimaki
Keyword(s):  
Sieve Tube ◽  
Soluble Proteins ◽  
Sieve Element ◽  
Tissue Extract ◽  
Companion Cell ◽  
Phloem Sap ◽  
Sieve Elements ◽  
Cell Complexes ◽  
Companion Cells ◽  
Sieve Tubes

Many kinds of proteins have been found in the sieve element–companion cell complexes by the analyses of phloem sap and microscopic observations. The cDNAs, which encode some of these sieve-tube proteins, have already been cloned. As mature sieve elements lack nuclei and most ribosomes, sieve-tube proteins have been hypothesized to be synthesized in the companion cells and then transported to the lumina of the functional sieve tubes through the plasmodesmata connecting the companion cells and sieve elements. Soluble proteins present in the sieve tubes can be collected by several techniques, such as incision or the aphid technique. The composition of the proteins in the phloem sap is unique compared with that of tissue extract, suggesting these proteins have important roles for the development and functions of sieve tubes.

Application of FRAP and digitized fluorescence microscopy to problems in cell membrane dynamics

1988 ◽  
Vol 46 ◽  
pp. 118-119
Author(s):  
K. Jacobson ◽  
A. Ishihara ◽  
B. Holifield ◽  
F. Zhang
Keyword(s):  
Fluorescence Microscopy ◽  
Cell Biology ◽  
Extended Period ◽  
Dynamic Structure ◽  
Living Cells ◽  
Membrane Dynamics ◽  
Molecular Cell Biology ◽  
Image Averaging ◽  
Single Living Cells ◽  
Single Living

Our laboratory is concerned with understanding the dynamic structure of the plasma membrane with particular reference to the movement of membrane constituents during cell locomotion. In addition to the standard tools of molecular cell biology, we employ both fluorescence recovery after photo- bleaching (FRAP) and digitized fluorescence microscopy (DFM) to investigate individual cells. FRAP allows the measurement of translational mobility of membrane and cytoplasmic molecules in small regions of single, living cells. DFM is really a new form of light microscopy in that the distribution of individual classes of ions, molecules, and macromolecules can be followed in single, living cells. By employing fluorescent antibodies to defined antigens or fluorescent analogs of cellular constituents as well as ultrasensitive, electronic image detectors and video image averaging to improve signal to noise, fluorescent images of living cells can be acquired over an extended period without significant fading and loss of cell viability.

Scanning x-ray fluorescence microscopy and principal component analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1752-1753
Author(s):  
Brian Cross
Keyword(s):  
Principal Component Analysis ◽  
Fluorescence Microscopy ◽  
Spatial Resolution ◽  
High Speed ◽  
Image Acquisition ◽  
Principal Component ◽  
Fluorescence Microscope ◽  
Acquisition Rate ◽  
X Ray ◽  
Speed Up

A relatively new entry, in the field of microscopy, is the Scanning X-Ray Fluorescence Microscope (SXRFM). Using this type of instrument (e.g. Kevex Omicron X-ray Microprobe), one can obtain multiple elemental x-ray images, from the analysis of materials which show heterogeneity. The SXRFM obtains images by collimating an x-ray beam (e.g. 100 μm diameter), and then scanning the sample with a high-speed x-y stage. To speed up the image acquisition, data is acquired "on-the-fly" by slew-scanning the stage along the x-axis, like a TV or SEM scan. To reduce the overhead from "fly-back," the images can be acquired by bi-directional scanning of the x-axis. This results in very little overhead with the re-positioning of the sample stage. The image acquisition rate is dominated by the x-ray acquisition rate. Therefore, the total x-ray image acquisition rate, using the SXRFM, is very comparable to an SEM. Although the x-ray spatial resolution of the SXRFM is worse than an SEM (say 100 vs. 2 μm), there are several other advantages.

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.

Two-photon excitation fluorescence microscopy in living systems

1993 ◽  
Vol 51 ◽  
pp. 154-155 ◽  
Author(s):  
David W. Piston
Keyword(s):  
Confocal Microscopy ◽  
Fluorescence Microscopy ◽  
Singlet State ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

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