Nodulation Factor

(noun)

Signaling molecules produced by bacteria known as rhizobia during the initiation of nodules on the root of legumes. A symbiosis is formed when legumes take up the bacteria.

Examples of Nodulation Factor in the following topics:

  • The Legume-Root Nodule Symbiosis

    • Many legumes have root nodules that provide a home for symbiotic nitrogen-fixing bacteria called rhizobia.
    • Rhizobia respond by releasing nodulation factor (sometimes just called nod factor), which stimulates nodule formation in plant roots.
    • Exposure to nod factor triggers the formation of deformed root hairs, which permit rhizobia to enter the plant.
    • Infection triggers rapid cell division in the root cells, forming a nodule of tissue.
    • Root nodules are formed when nitrogen fixing bacteria called rhizobia enter the cells of a host plant.
  • Early Discoveries in Nitrogen Fixation

    • He found that the nodules on the roots of legumes are the location where nitrogen fixation takes place.
    • Hellriegel did not determine what factors in the root nodules carried out nitrogen fixation.
    • Martinus Willem Beijerinck (March 16, 1851 – January 1, 1931), a Dutch microbiologist and botanist, explored the mechanism responsible, discovering that the root nodules contained microbes.
    • The bacteria in the root nodules are needed to provide nitrogen for legume growth, while the rhizobia are dependent on the root nodules as a environment to grow.and a source of nutrition.
  • Symbiosis between Bacteria and Eukaryotes

    • Symbionts may fix more nitrogen in soils than free-living organisms by a factor of 10.
    • Soil bacteria, collectively called rhizobia, are able to symbiotically interact with legumes to form nodules: specialized structures where nitrogen fixation occurs .
    • Nitrogenase, the enzyme that fixes nitrogen, is inactivated by oxygen, so the nodule provides an oxygen-free area for nitrogen fixation to take place.
    • Soybean (Glycine max) is a legume that interacts symbiotically with the soil bacterium Bradyrhizobium japonicum to form specialized structures on the roots called nodules where nitrogen fixation occurs.
  • Thyroid Gland Disorders

    • Many individuals may find the presence of thyroid nodules in the neck.
    • The majority of these thyroid nodules are benign (non-cancerous).
    • If the nodule is found to be non-cancerous, no other treatment is required.
    • If the nodule is suspicious, then surgery is recommended.
    • One may be able to feel a hard nodule in the neck.
  • Physical Properties of Soil

    • In some soils, the B horizon contains nodules or a layer of calcium carbonate.
    • The thickness of the layers is also variable, depending on the factors that influence soil formation.
  • Laryngitis and Cancer of the Larynx

    • In most instances, the symptoms accompanying laryngitis are more directly linked to the causative factor, such as a viral infection.
    • At times, persistent hoarseness or loss of voice (dysphonia) is a result of vocal cord nodules in which case physicians may recommend a course of treatment that may include a surgical procedure and/or speech therapy.
  • Regulating Immune Tolerance

    • M cells are located in the Peyer's patch, which is a lymphoid nodule.
    • Immune tolerance is brought about by specialized APCs in the liver, lymph nodes, small intestine, and lung that present harmless antigens to a diverse population of regulatory T (Treg) cells: specialized lymphocytes that suppress local inflammation and inhibit the secretion of stimulatory immune factors.
  • Anaerobiosis and N2 Fixation

    • In plants infected with Rhizobium, (legumes such as alfalfa or soybeans), the presence of oxygen in the root nodules would reduce the activity of the oxygen-sensitive nitrogenase.
    • Leghemoglobin buffers the concentration of free oxygen in the cytoplasm of infected plant cells to ensure the proper function of root nodules.
    • Leghemoglobin buffers the concentration of free oxygen in the cytoplasm of infected plant cells to ensure the proper function of root nodules.
  • Nitrogen Fixation: Root and Bacteria Interactions

    • Soil bacteria, collectively called rhizobia, symbiotically interact with legume roots to form specialized structures called nodules in which nitrogen fixation takes place .
    • Soybean roots contain (a) nitrogen-fixing nodules.
    • Cells within the nodules are infected with Bradyrhyzobium japonicum, a rhizobia or "root-loving" bacterium.
  • Endophytes and Plants

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