Ultrastructure of cell division in the fusiform cells of the vascular cambium of Robinia pseudoacacia

Trees ◽  
1997 ◽  
Vol 11 (4) ◽  
pp. 203-215 ◽  
Author(s):  
J. J. Farrar ◽  
Ray F. Evert
IAWA Journal ◽  
2018 ◽  
Vol 39 (2) ◽  
pp. 191-208 ◽  
Author(s):  
Anna B. Wilczek ◽  
Muhammad Iqbal ◽  
Wieslaw Wloch ◽  
Marcin Klisz

ABSTRACTAll cell types of the secondary xylem arise from the meristematic cells (initials) of the vascular cambium and grow under mechanical constraints emerging from the circular-symmetrical geometry that characterises many tree trunks. The course of intrusive growth of cambial initials has been elucidated, but is yet to be described in the case of xylem fibres. This study explains the geometry of intrusive growth of the secondary xylem fibres in the trunk ofRobinia pseudoacacia.Long series of serial semi-thin sections of the vascular cambium and the differentiating secondary xylem were analysed. Since fibres grow in close vicinity to expanding cells of the derivatives of the vascular cambium, we assumed that they have similar growth conditions. Dealing with the cylindrical tissue of the vascular cambium in a previous study, we used a circularly symmetrical equation for describing the growth mechanism of cambial initials. Like the cambial initials, some of the cambial derivatives differentiating into the various cell types composing the secondary xylem also exhibit intrusive growth between the tangential walls of adjacent cells. As seen in cross sections of the cambium, intrusively growing initials form slanted walls by a gradual transformation of tangential (periclinal) walls into radial (anticlinal) walls. Similarly, the intrusive growth of xylem fibres manifests initially as slants, which are formed due to axial growth of the growing cell tips along the tangential walls of adjacent cells. During this process, the tangential walls of adjacent cells are partly separated and dislocated from the tangential plane. The final shape of xylem fibres, or that of vessel elements and axial parenchyma cells, depends upon the ratio of their intrusiveversussymplastic growths in the axial, circumferential and radial directions.


Trees ◽  
1997 ◽  
Vol 11 (4) ◽  
pp. 203 ◽  
Author(s):  
J. J. Farrar ◽  
Ray F. Evert

IAWA Journal ◽  
1994 ◽  
Vol 15 (2) ◽  
pp. 157-160 ◽  
Author(s):  
Uwe Schmitt ◽  
Walter Liese

The formation of tyloses in vessels of Robinia pseudoacacia L. after wounding was investigated by transmission electron microscopy. Some tyloses in earlywood vessels exhibit cell division. The young walls between mother and daughter tyloses with primary wall-like appearance evince plasmodesmata; pits develop simultaneously with wall thickening.


1984 ◽  
Vol 62 (4) ◽  
pp. 847-857 ◽  
Author(s):  
James D. Mauseth ◽  
Gloria Montenegro ◽  
Alan M. Walckowiak

Many of the large columnar cacti Trichocereus chilensis near Santiago are infected by Tristerix aphyllus. This is one of the most highly reduced seed plants known: as it is an endoparasite, inflorescences are the only parts of the plant ever to emerge from the host, all the rest exists as an endophytic haustorial system; roots, vegetative stems, and leaves are not produced. After infection, the parasite spreads through the thick cortex of the host, reaching the vascular cambium and conducting tissues. It continues to grow intrusively throughout all tissues of the host shoot. In its invasive stage it occurs as a "myceliumlike" mass of uniseriate filaments that grow between host cells but only rarely enter them. Later growth is by longitudinal cell division that produces irregular parenchymatous strands. Eventually, xylem and phloem differentiate in the endophytic strands; the phloem is like that of other seed plants, but the xylem is almost pure parenchyma, with only occasional, idioblastic tracheary elements. Strands close to the epidermis of the host are able to produce adventitious flower buds that emerge through either soft regions in the epidermis (the areoles) or through accidental breaks in it. The flower stalk may persist, forming a small perennial inflorescence that has well-developed xylem, phloem, and periderm but is without leaves. Host cells appear healthy and normal, with no sign of damage caused by the presence of the parasite.


Trees ◽  
1997 ◽  
Vol 11 (4) ◽  
pp. 191-202 ◽  
Author(s):  
J. J. Farrar ◽  
Ray F. Evert

Author(s):  
L. M. Lewis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.


Author(s):  
Krishan Awtar

Exposure of cells to low sublethal but mitosis-arresting doses of vinblastine sulfate (Velban) results in the initial arrest of cells in mitosis followed by their subsequent return to an “interphase“-like stage. A large number of these cells reform their nuclear membranes and form large multimicronucleated cells, some containing as many as 25 or more micronuclei (1). Formation of large multinucleate cells is also caused by cytochalasin, by causing the fusion of daughter cells at the end of an otherwise .normal cell division (2). By the repetition of this process through subsequent cell divisions, large cells with 6 or more nuclei are formed.


Author(s):  
Ann Cleary

Microinjection of fluorescent probes into living plant cells reveals new aspects of cell structure and function. Microtubules and actin filaments are dynamic components of the cytoskeleton and are involved in cell growth, division and intracellular transport. To date, cytoskeletal probes used in microinjection studies have included rhodamine-phalloidin for labelling actin filaments and fluorescently labelled animal tubulin for incorporation into microtubules. From a recent study of Tradescantia stamen hair cells it appears that actin may have a role in defining the plane of cell division. Unlike microtubules, actin is present in the cell cortex and delimits the division site throughout mitosis. Herein, I shall describe actin, its arrangement and putative role in cell plate placement, in another material, living cells of Tradescantia leaf epidermis.The epidermis is peeled from the abaxial surface of young leaves usually without disruption to cytoplasmic streaming or cell division. The peel is stuck to the base of a well slide using 0.1% polyethylenimine and bathed in a solution of 1% mannitol +/− 1 mM probenecid.


Author(s):  
Vladimir Popenko ◽  
Natalya Cherny ◽  
Maria Yakovleva

Highly polyploid somatic nucleus (macronucleus) of ciliate Bursaria truncatella under goes severe changes in morphology during cell division. At first, macronucleus (Ma) condences, diminishes in size and turns perpendicular to longitudinal axis of the cell. After short time, Ma turns again, elongates and only afterwards the process of division itself occurs. The biological meaning of these phenomena is not clear.Localization of RNA in the cells was performed on sections of ciliates B. truncatella, embedded in “Lowicryl K4M” at various stages: (1) before cell division (Figs. 2,3); (11) at the stage of macronucleus condensation; (111) during elongation of Ma (Fig.4); (1111) in young cells (0-5min. after division). For cytochemical labelling we used RNaseAcolloidal gold complexes (RNase-Au), which are known to bind to RNA containing cell ularstructures with high specificity. The influence of different parameters on the reliability and reproducibility of labelling was studied. In addition to the factors, discussed elsewhere, we found that the balance of mono- and bivalent cations is of great significance.


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