scholarly journals Aeration Pathways in Soybean Root Nodules

1973 ◽  
Vol 26 (4) ◽  
pp. 729 ◽  
Author(s):  
FJ Bergersen ◽  
DJ Goodchild
Keyword(s):  
Electron Microscopy ◽  
Root Nodule ◽  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Intercellular Spaces ◽  
Soybean Root

Soybean root nodule tissues contain many interconnected gas-filled intercellular spaces. They have been studied, in fresh and embedded tissue during the development and functional life of the nodules, by light and electron microscopy.

Spheroplasts of Rhizobium japonicum

1984 ◽  
Vol 30 (3) ◽  
pp. 415-419 ◽  
Author(s):  
James O. Berry ◽  
Alan G. Atherly
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Root Nodules ◽  
Rhizobium Japonicum ◽  
Soybean Root ◽  
Scanning Electron

Speroplasts of Rhizobium japonicum strains 61A76, USDA 31, and 110 were prepared by culturing cells in the presence of glycine, followed by treatment with lysozyme. The cells were examined by scanning electron microscopy before, during, and after becoming spheroplasts and found to be morphologically similar to the bacteroid forms found in soybean root nodules. Some similarities of spheroplast and bacteroid formation are discussed.

Studies on possible routes of ammonium assimilation in soybean root nodule bacteroids

1973 ◽  
Vol 19 (12) ◽  
pp. 1493-1499 ◽  
Author(s):  
Stanley D. Dunn ◽  
Robert V. Klucas
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Assimilation ◽  
Reductive Amination ◽  
Root Nodule ◽  
Root Nodules ◽  
Ammonium Assimilation ◽  
Kinetic Properties ◽  
Transferase Activity ◽  
Soybean Root

Glutamine amide–2-oxoglutarate aminotransferase NAD+ oxidoreductase (GOGAT), glutamine synthetase (GS), glutamate dehydrogenase (GD), and alanine dehydrogenase (AD) were studied in soybean root nodules. GS, GOGAT, and AD were present in bacteroids at levels that could account for ammonium assimilation, but GD activity was quite low. The total activities of GS and GD were higher in the cytosol than in the bacteroids by factors of 20 and 7, respectively, whereas GOGAT was not detected in the cytosol. GS (transferase activity) was inhibited by alanine, CTP, glycine, and tryptophan at 5 mM but was relatively unaffected by asparagine, aspartic acid, CMP, glucosamine, and histidine at 5 mM. GOGAT activity was unaffected by ATP, ADP, 8-hydroxyquinoline, and 1,10-phenanthroline but was inhibited by EDTA, citrate, and parachloromercuribenzoate. GOGAT activity (reductive amination) was also inhibited 97% by preincubation with 10−4 M azaserine for 30 min but GD activity was inhibited only 13%. The apparent Km values for NH4+ by AD was 7.4 × 10−3 M and by GD was 7.3 × 10−2 M while for glutamine by GOGAT it was 9.3 × 10−5 M. Activities and kinetic properties for these enzymes may suggest potential routes of nitrogen assimilation in vivo.

scholarly journals WOUND HEALING AND COLLAGEN FORMATION

1962 ◽  
Vol 12 (3) ◽  
pp. 533-551 ◽  
Author(s):  
Russell Ross ◽  
Earl P. Benditt
Keyword(s):  
Electron Microscopy ◽  
Wound Healing ◽  
Protein Synthesis ◽  
Small Groups ◽  
Guinea Pigs ◽  
Light And Electron Microscopy ◽  
Dense Matter ◽  
Skin Wounds ◽  
Intercellular Spaces ◽  
Collagen Formation

The sequence encountered in healing skin wounds in scorbutic guinea pigs has been examined by methods of light and electron microscopy. Linear incisions in the skin of female guinea pigs fed a scorbutigenic diet were allowed to heal. The wounds were removed for examination at 1, 3, 5, 9, and 14 days after wounding. The fibroblasts of the scorbutic wounds differ from those of the controls in three major aspects. First, little collagen is present within the intercellular spaces, although small groups of individual collagen fibrils can be found adjacent to some of the fibroblasts; in addition, large amounts of somewhat fibrillar, poorly structured, dense matter are present throughout the extracellular regions. The second alteration consists of large aggregates of intracytoplasmic lipid deposits present within the majority of the fibroblasts. Third, the endoplasmic reticulum of the fibroblasts is altered in form from that of the controls. The profiles of the cisternae are round, non-continuous within the plane of section, and are less extensively developed than in the controls. An increased macrophagic activity of the histiocytes is also described. These changes are discussed in light of the available biochemical data associated with this abnormality of protein synthesis.

Development of intercellular junctions in the pulmonary epithelium of the foetal lamb

1978 ◽  
Vol 32 (1) ◽  
pp. 307-324
Author(s):  
E.E. Schneeberger ◽  
D.V. Walters ◽  
R.E. Olver
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Tight Junctions ◽  
Lung Development ◽  
Light And Electron Microscopy ◽  
Intercellular Junctions ◽  
Intercellular Spaces ◽  
Thin Sections ◽  
Epithelial Tight Junctions ◽  
Foetal Lamb

The integrity of epithelial tight junctions in foetal mammalian lungs is essential to maintain the unique ionic composition of lung liquid, and to prevent leakage of serum proteins into peripheral air spaces. In the present study the development of intercellular junctions of the lining epithelium of foetal lamb lungs during gestation was examined by light and electron microscopy. Both thin sections and freeze-fracture replicas were examined by electron microscopy. By 39 days of gestation, epithelial tight junctions consist of a minimum of 3.1 +/− 1.6 (s.D.) and a maximum of 5.8 +/− 2.0 discontinuous rows of particles and short segments of strands on P face ridges and in complementary E face grooves, while from 58 to 76 days they are composed of a network of 4.3 +/− 1.6 to 7.7 +/− 1.9 focally interrupted P face strands. Complementary replicas show that many of the discontinuities on the P face are due to separation of junctional particles on to the E face during fracturing, and not to an absence of junctional particles. From 76 days to term, epithelial tight junctions (exclusive of upper airway epithelium which was not examined) resemble those of adult lungs, and consist of a continuous network of 4.5 +/− 2.0 to 7.5 +/− 2.5 P face strands and complementary particle-free grooves. Permeability measurements, published elsewhere, indicate that the epithelium is functionally ‘tight’ from 69 days onwards. Tight junctions in peripheral air-space epithelium, therefore, are structurally continuous and functionally ‘tight’ early in foetal lung development, and form seals at one end of long, narrow intercellular spaces; these features may be important for coupled ion and water transport. When the bounding epithelial cells become flattened, these narrow intercellular spaces remain intact as a result of complex interdigitations of adjacent cell membranes. Desmosomes were present throughout gestation near the abluminal side of the tight junctions and occasionally near the base of the intercellular space. These junctions may serve to connect cells to each other at a time when tight junctions may be mechanically weak. In addition, gap junctions are associated with tight junctions from the glandular through the canalicular stages of lung development. They disappear by 120 days when the epithelial cells are differentiated.

scholarly journals Cellular Location and Concentration of Leghaemoglobin in Soybean Root Nodules

1973 ◽  
Vol 26 (4) ◽  
pp. 741 ◽  
Author(s):  
FJ Bergersen ◽  
DJ Goodchild
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Fresh Tissue ◽  
Cellular Location ◽  
Soybean Root ◽  
Tissue Sections

The reaction of leghaemoglobin (Lb) with oxidized 3,3'-diaminobenzidine has been used to demonstrate the localization of this haemoprotein within the membrane envelopes surrounding the bacteroids in soybean root nodule cells. In fresh tissue sections mounted in a modified Honda medium, the reagent stained the envelope contents a brick-red colour.

A correlated light and electron microscopic study of symbiotic growth and differentiation in Pisum sativum root nodules

1976 ◽  
Vol 54 (18) ◽  
pp. 2163-2186 ◽  
Author(s):  
William Newcomb
Keyword(s):  
Electron Microscopy ◽  
Pisum Sativum ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Infection Thread ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Garden Pea ◽  
Host Cytoplasm

Plants of the garden pea Pisum sativum cv. Little Marvel were grown in aeroponic culture to facilitate observations and microscopy and were inoculated with Rhizobium leguminosarum, and nodules were sampled at five weekly intervals for light and electron microscopy. The invasion of the cortical cells by the infection thread, the structure of the infection thread, and the release of bacteria from it into the host cytoplasm and the subsequent symbiotic growth and differentiation of the two organisms are described in detail. The fine structure of the nodule is correlated with light microscopic observations and morphogenesis. A restriction in the use of the term 'vesicle' is proposed because of the current multiple and confusing usage of the term. The loss of the nodule meristem and its morphogenetic significance are discussed.

Ultrastructural evidence for the existence of actinorhizal symbioses in the late Pleistocene

1980 ◽  
Vol 58 (15) ◽  
pp. 1612-1620 ◽  
Author(s):  
Dwight Baker ◽  
Norton G. Miller
Keyword(s):  
Electron Microscopy ◽  
Root Nodule ◽  
Root Nodules ◽  
Eastern North America ◽  
Independent Evidence ◽  
Qualitative And Quantitative ◽  
Ultrastructural Evidence ◽  
Shepherdia Canadensis ◽  
Nodule Endophytes ◽  
Scanning Electron

Macrofossil actinorhizal root nodules discovered in sediments about 11 500 radiocarbon years old in northern Vermont, U.S.A., were studied by scanning electron microscopy. Evidence of an endophytic microsymbiont was observed within the cortex of the fossil nodules. A comparative study as undertaken using root nodules from species of Alnus, Dryas, Elaeagnus, Myrica, Shepherdia, and Vicia native to eastern North America in an effort to determine the identity of the fossils. From qualitative and quantitative differences observed among the root nodule endophytes, it was concluded that the fossil nodules contained actinomycetes morphologically similar to those of extant Elaeagnaceae. The fossils are probably from plants of Elaeagnus commutata and (or) Shepherdia canadensis based on independent evidence of the representation of these species in the plant macrofossil assemblage.

scholarly journals Soybean Root Nodule and Rhizosphere Microbiome: Distribution of Rhizobial and Nonrhizobial Endophytes

2021 ◽  
Vol 87 (10) ◽  
Author(s):  
Parris Mayhood ◽  
Babur S. Mirza
Keyword(s):  
Plant Growth ◽  
Random Process ◽  
Host Plant ◽  
Soil Nitrogen ◽  
Root Nodule ◽  
Root Nodules ◽  
Bacterial Endophytes ◽  
Content Type ◽  
Soybean Root ◽  
Selection Of

ABSTRACT Soybean root nodules are known to contain a high diversity of both rhizobial endophytes and nonrhizobial endophytes (NREs). Nevertheless, the variation of these bacteria among different root nodules within single plants has not been reported. So far, it is unclear whether the selection of NREs among different root nodules within single plants is a random process or is strictly controlled by the host plant to favor a few specific NREs based on their beneficial influence on plant growth. As well, it is also unknown if the relative frequency of NREs within different root nodules is consistent or if it varies based on the location or size of a root nodule. We assessed the microbiomes of 193 individual soybean root nodules from nine plants using high-throughput DNA sequencing. Bradyrhizobium japonicum strains occurred in high abundance in all root nodules despite the presence of other soybean-compatible rhizobia, such as Ensifer, Mesorhizobium, and other species of Bradyrhizobium in soil. Nitrobacter and Tardiphaga were the two nonrhizobial genera that were uniformly detected within almost all root nodules, though they were in low abundance. DNA sequences related to other NREs that have frequently been reported, such as Bacillus, Pseudomonas, Flavobacterium, and Variovorax species, were detected in a few nodules. Unlike for Bradyrhizobium, the low abundance and inconsistent occurrence of previously reported NREs among different root nodules within single plants suggest that these microbes are not preferentially selected as endophytes by host plants and most likely play a limited part in plant growth as endophytes. IMPORTANCE Soybean (Glycine max L.) is a valuable food crop that also contributes significantly to soil nitrogen by developing a symbiotic association with nitrogen-fixing rhizobia. Bacterial endophytes (both rhizobial and nonrhizobial) are considered critical for the growth and resilience of the legume host. In the past, several studies have suggested that the selection of bacterial endophytes within root nodules can be influenced by factors such as soil pH, nutrient availability, host plant genotype, and bacterial diversity in soil. However, the influence of size or location of root nodules on the selection of bacterial endophytes within soybean roots is unknown. It is also unclear whether the selection of nonrhizobial endophytes within different root nodules of a single plant is a random process or is strictly regulated by the host. This information can be useful in identifying potential bacterial species for developing bioinoculants that can enhance plant growth and soil nitrogen.

scholarly journals Proliferation of peroxisomes in pea root nodules - an influence of NaCI- or Hg2+- stress conditions

2011 ◽  
Vol 76 (4) ◽  
pp. 287-298 ◽  
Author(s):  
Wojciech Borucki
Keyword(s):  
Oxidative Stress ◽  
Electron Microscopy ◽  
Nitrogen Fixation ◽  
Pisum Sativum ◽  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Nitrogen Fixing ◽  
Morphometric Measurements ◽  
Meristematic Cells ◽  
Pea Root

Morphometric procedures were used to examine peroxisome number and di-stribution in pea (<em>Pisum sativum</em> L.) root nodules under NaCl (50 mM) or HgCl<sub>2</sub> (7.3 µM) treatment. Peroxisomes were visualized cytochemically in meristem, invasion zone and prefixing zone of pea root nodules by catalase (EC 1.11.1.6) activity. The observations using light and electron microscopy revealed that the peroxisomes were predominantly spherical in shape and showed catalase activity. In nitrogen fixation zone, catalase active peroxisomes were observed occasionally. Bacteroids of nitrogen fixing zone showed enhanced cata-lase activity probably as a response to higher level of oxidative stress. Fluorescence microscopy investigations revealed enhanced level of (homo)glutathione in prefixing and nitrogen-fixing zone of NaCl- and Hg<sup>2+</sup>treated nodules, which served as an indicator of antioxidative response. Morphometric measurements revealed that during differentiation of meristematic cells into central tissue (bacteroidal tissue) cells an increase in peroxisome number was observed in unstressed nodules. Peroxisomes located in meristem, invasion zone and prefixing zone of NaCl- and Hg<sup>2+</sup>-treated nodules outnumbered that in control nodules. A substantial enlargement of peroxisome profiles was detected in NaCl- and Hg<sup>2+</sup>treated nodules. Peroxisome divisions observed in meristematic and infection thread penetration zone were responsible for an increase in peroxisome number.

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