scholarly journals A comparative cytological and morphometric analysis of vacuolation in central tissue of the effective and ineffective pea (Pisum sativum L.) root nodules

2011 ◽  
Vol 76 (2) ◽  
pp. 109-118 ◽  
Author(s):  
Wojciech Borucki
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Thin Layers ◽  
Central Vacuole ◽  
Dynamic Changes ◽  
Pea Root ◽  
Dimensional Reconstruction ◽  
Infected Cells

Vacuoles play very important physiological roles in plant cells. Pea root nodules, which exhibit distinct zonation (meristematic zone and central tissue zones), may serve as a good experimental model for the investigations of vacuole development and its importance to cell and tissue functioning. Moreover, the nodule central tissue is composed of both infected and uninfected cells which play different physiological roles and differ in the level of vacuolation. Cytological observations revealed that central vacuoles of the infected cells of the effective nodules expand toward cell walls. Thus only thin layers of the cytoplasm separate each central vacuole from plasma membrane and cell wall. This finding is discussed from the viewpoint of improved exchange of solutes and water between the central vacuole and apoplast of the infected cell. Three-dimensional reconstruction of the vacuoles of infected cells within a fragment of effective nodule central tissue, showed their spatial arrangement. Possible advantages coming from the spatial arrangement of vacuoles within the central tissue are discussed. A comparative study of the central tissue (bacteroidal tissue) and meristem vacuolation of the effective and ineffective pea root nodules is also presented. Morphometric measurements revealed that the effective nodule central tissue was more vacuolated than the ineffective one. It was proved that maturation of the infected cells involves dynamic changes in their vacuolation. Having numerous fixing nitrogen bacteroids, the infected cells of effective central tissue were less vacuolated than uninfected cells. On the other hand, both infected and uninfected cells of the effective central tissue showed a much higher level of vacuolation in nitrogen-fixing zone than cells of the same type in ineffective tissue. These results indicate that vacuolation is an important factor in development and functioning of pea root nodule central tissue.

Organization of microtubules in developing pea root nodule cells

2001 ◽  
Vol 79 (7) ◽  
pp. 777-786
Author(s):  
A L Davidson ◽  
W Newcomb
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Root Nodules ◽  
Cell Cortex ◽  
Cortical Microtubules ◽  
Microtubule Organization ◽  
Pea Root ◽  
Fluorescence And Electron Microscopy ◽  
Infected Cells ◽  
Cytoplasmic Microtubules

Pisum sativum L. (pea) root nodule cells undergo many cellular changes in response to infection by Rhizobium leguminosarum bv. viciae. These include cell growth, organelle reorganization, and changes relating to the increase in the number of bacteria within the cell. The objective of this study was to characterize microtubule organization during nodule cell development. The organization of microtubules was examined in developing pea root nodules using fluorescence and electron microscopy techniques. Immunolabelling of microtubules in meristematic cells showed diffuse fluorescence in the cell cortex and adjacent to the nuclear envelope. Recently infected cells contained randomly oriented cortical microtubules and cytoplasmic microtubules that were fragmented with diffuse fluorescence. Infected cells contained an extensive network of long, randomly arranged cortical microtubules with some parallel bundles. Cytoplasmic microtubules in single optical sections of infected cells appeared as short undulating filaments; however, overlapping images from a Z-series of an infected cell showed that the microtubules are long and wavy, and generally radiate inward from the cell cortex.Key words: nodule, microtubules, Rhizobium, pea, symbiosis.

Changes in actin microfilament arrays in developing pea root nodule cells

2001 ◽  
Vol 79 (7) ◽  
pp. 767-776 ◽  
Author(s):  
A L Davidson ◽  
W Newcomb
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Infection Process ◽  
Host Cells ◽  
Actin Microfilaments ◽  
Symbiotic Associations ◽  
Actin Microfilament ◽  
Pea Root ◽  
Microfilament Bundles ◽  
Infected Cells

Various microorganisms that form symbiotic associations with plant roots alter the cytoskeleton of host cells. The objective of this study was to determine the organization of actin microfilaments in developing Pisum sativum L. (pea) root nodule cells at various stages after infection by Rhizobium leguminosarum bv. viciae. Fluorescently labelled microfilaments in uninfected pea root nodule cells occur in association with the nucleus, along cytoplasmic strands, and as long microfilament bundles randomly organized in the cortex of the cell. These actin arrays are also present in recently infected cells that have been invaded by an infection thread and contain a small number of bacteroids. In addition, the recently infected cells contain diffuse cytoplasmic actin, long actin microfilament bundles near the vacuole, and a nuclear-associated network of microfilament bundles. In older infected cells, the predominant array is a network of cytoplasmic microfilaments that are wavy and extend in multiple directions within the cell; the network is equally abundant in all regions of the cytoplasm and may interact with the bacteroids and organelles. Thus, actin microfilaments reorganize during the pea root nodule infection process to form distinct arrays whose organization depends on the stage of infection.Key words: nodule, actin microfilaments, Rhizobium, pea, symbiosis.

scholarly journals Development of cyclic shedding teeth from semi-shedding teeth: the inner dental arcade of the stem osteichthyan Lophosteus

2017 ◽  
Vol 4 (5) ◽  
pp. 161084 ◽  
Author(s):  
Donglei Chen ◽  
Henning Blom ◽  
Sophie Sanchez ◽  
Paul Tafforeau ◽  
Tiiu Märss ◽  
...  
Keyword(s):  
First Generation ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Early Form ◽  
Dental Lamina ◽  
Dimensional Reconstruction ◽  
Dental Arcade ◽  
The Individual ◽  
Tooth Buds ◽  
Synchrotron Microtomography

The numerous cushion-shaped tooth-bearing plates attributed to the stem group osteichthyan Lophosteus superbus , which are argued here to represent an early form of the osteichthyan inner dental arcade, display a previously unknown and presumably primitive mode of tooth shedding by basal hard tissue resorption. They carry regularly spaced, recumbent, gently recurved teeth arranged in transverse tooth files that diverge towards the lingual margin of the cushion. Three-dimensional reconstruction from propagation phase-contrast synchrotron microtomography (PPC-SRµCT) reveals remnants of the first-generation teeth embedded in the basal plate, a feature never previously observed in any taxon. These teeth were shed by semi-basal resorption with the periphery of their bases retained as dentine rings. The rings are highly overlapped, which evidences tooth shedding prior to adding the next first-generation tooth at the growing edge of the plate. The first generation of teeth is thus diachronous. Successor teeth at the same sites underwent cyclical replacing and shedding through basal resorption, producing stacks of buried resorption surfaces separated by bone of attachment. The number and spatial arrangement of resorption surfaces elucidates that basal resorption of replacement teeth had taken place at the older tooth sites before the addition of the youngest first-generation teeth at the lingual margin. Thus, the replacement tooth buds cannot have been generated by a single permanent dental lamina at the lingual edge of the tooth cushion, but must have arisen either from successional dental laminae associated with the individual predecessor teeth, or directly from the dental epithelium of these teeth. The virtual histological dissection of these Late Silurian microfossils broadens our understanding of the development of the gnathostome dental systems and the acquisition of the osteichthyan-type of tooth replacement.

scholarly journals Some new aspects of the pea (Pisum sativum L.) root nodule ultrastructure

2014 ◽  
Vol 65 (3-4) ◽  
pp. 221-233 ◽  
Author(s):  
Wojciech Borucki
Keyword(s):  
Nitrogen Assimilation ◽  
Root Nodule ◽  
Three Dimensional ◽  
Gas Diffusion ◽  
Dimensional Structure ◽  
Bacterial Cells ◽  
Symbiotic System ◽  
Pisum Sativum L ◽  
Infected Cells ◽  
Nodule Ultrastructure

Unequal cell divisions were observed in the meristem of pea root nodule. Since after such divisions only the bigger cells become infected then those divisions play a significant role in the formation of the three-dimensional structure of the bacteroidal tissue. In the infected cells of the young ineffective bacteroidal tissue the first host reaction to the incompatibility of the symbiotic system is the RER membranes aggregation. In effective symbiosis RER membranes form permanent sites of contact with the peribacteroidal membranes thus connecting all the symbiosoms in the cell. Possibly that ensures the synchronisation of the differentiation processes of the bacteroids and/or their simultaneous degeneration. The presence of membraneous structures in the form of rings is a characteristic feature of effective bacteroids. It is postulated that the structures are directly connected with nitrogen assimilation. Structures X and Y which are present in the bacteroids of the effective and ineffective symbiosis may be connected with the adaptation of bacterial cells to lowered oxygen pressure in bacteroidal tissue and their transformation (structures X) into bacteroids. The presence of the cytoplasm (or cytoplasmatic remnants) of the infected cells was observed in the intercellular spaces. It is sugested that it is a way, so far unknown, of the gas diffusion regulation in bacteroidal tissue.

scholarly journals Potassium content diminishes in infected cells of Medicago truncatula nodules due to the mislocation of channels MtAKT1 and MtSKOR/GORK

2020 ◽  
Author(s):  
Elena E Fedorova ◽  
Teodoro Coba de la Peña ◽  
Victoria Lara-Dampier ◽  
Natalia A Trifonova ◽  
Olga Kulikova ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Nodule ◽  
Root Nodules ◽  
Phylogenetic Analyses ◽  
Gene Copy ◽  
Gene Localization ◽  
K Channel ◽  
Infected Cells ◽  
Plant Ion Channels ◽  
Mature Nodule

Root nodule-infected cells have defects in K+ balance, as compared with non-infected cells, probably due to variation in the location of K+ channel proteins MtAKT1 and MtSKOR/GORK. Abstract Rhizobia establish a symbiotic relationship with legumes that results in the formation of root nodules, where bacteria encapsulated by a membrane of plant origin (symbiosomes), convert atmospheric nitrogen into ammonia. Nodules are more sensitive to ionic stresses than the host plant itself. We hypothesize that such a high vulnerability might be due to defects in ion balance in the infected tissue. Low temperature SEM (LTSEM) and X-ray microanalysis of Medicago truncatula nodules revealed a potassium (K+) decrease in symbiosomes and vacuoles during the life span of infected cells. To clarify K+ homeostasis in the nodule, we performed phylogenetic and gene expression analyses, and confocal and electron microscopy localization of two key plant Shaker K+ channels, AKT1 and SKOR/GORK. Phylogenetic analyses showed that the genome of some legume species, including the Medicago genus, contained one SKOR/GORK and one AKT1 gene copy, while other species contained more than one copy of each gene. Localization studies revealed mistargeting and partial depletion of both channels from the plasma membrane of M. truncatula mature nodule-infected cells that might compromise ion transport. We propose that root nodule-infected cells have defects in K+ balance due to mislocation of some plant ion channels, as compared with non-infected cells. The putative consequences are discussed.

scholarly journals Root nodule structure in Chamaecytisus podolicus

2017 ◽  
Vol 70 (2) ◽  
Author(s):  
Monika Skawińska ◽  
Barbara Łotocka ◽  
Tomasz Ruszkowski ◽  
Piotr Banaszczak ◽  
Ewa Znojek
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Structural Features ◽  
Meristematic Cells ◽  
Indeterminate Nodules ◽  
Infection Threads ◽  
Root Nodule Structure ◽  
Infected Cells ◽  
First Time ◽  
Sister Cells

By means of microscopic analyses, it was shown that root nodules formed by <em>Chamaecytisus podolicus</em> exhibited all structural features typical for indeterminate nodules of temperate genistean shrubs: (<em><strong>i</strong></em>) apical nodule meristem composed of infected and non-infected domains, (<em><strong>ii</strong></em>) parenchymatous bacteroid-containing tissue with infected cells only resulting from mitotic activity of infected meristematic cells, (<em><strong>iii</strong></em>) absence of infection threads, and (<em><strong>iv</strong></em>) convoluted bacteroids singly enclosed in a symbiosome membrane. For the first time, it was shown that the nodule meristem is organized into longitudinal files of sister cells.

scholarly journals Structural bases for effectivity of bacteroidal tissue in pea root nodules formed by effective or ineffective bacteria strain

2014 ◽  
Vol 66 (2) ◽  
pp. 165-176
Author(s):  
Wojciech Borucki
Keyword(s):  
Infected Cell ◽  
Surface Area ◽  
Root Nodules ◽  
Cellular Structures ◽  
Volume Increase ◽  
Common Features ◽  
Cell Compartments ◽  
Pea Root ◽  
Infected Cells

The performed comparison included changes in volume and surface area of the chosen cellular structures during the development of the effective and ineffective bacteroidal tissue of pea root nodules. It has been noted that the increase of the volume of the infected cell in effective nodules is associated with the increase of the volume of vacuome, symbiosomes and cystol while in ineffective bacteroidal tissue with the increase of the starch volume and to a lesser degree symbiosomes and cytosol volumes. In turn, the volume increase of uninfected cells in effective bacteroidal tissue is associated with the volume increase of vacuome and cystol and in case of ineffective nodules with the increase of the volumes of cystol, starch, and to a lesser degree, vacuome. This data point to the disturbances in the vacuolation process of infected and uninfected cells in ineffective bacteroidal tissue. In effective symbiosis the volume of vacuome and peribacteroidal spaces in the infected cells change in the dependent way that stresses common features of these two compartments. It has also been observed that the surface area and/or volume of such infected cell compartments as plastids, mitochondria, symbiosomes and cystol change in a more co-ordinated way during the development of the effective than ineffective bacteroidal tissue. All these facts create a basis for discussion about the role of particular compartments in the functioning of bacteroidal tissue.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

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