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.

  • 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.

  • Endophytes and Plants

  • Rheumatic Fever

  • Other Fungi Involved in Respiratory Disease

    • Symptoms include productive coughing, nodules and cavitations of the lungs, fibrosis, and swollen hilar lymph nodes.

  • Blastomycosis

    • Blastomycosis is histologically associated with granulomatous nodules.

  • The Nitrogen Cycle

    • Some nitrogen fixing bacteria live in the root nodules of legumes where they produce ammonia in exchange for sugars.

  • Coccidiomycosis

    • Serious complications include severe pneumonia, lung nodules, and disseminated disease, where the fungus spreads throughout the body.
    • Histopathological changes in a case of coccidioidomycosis of the lung showing a large fibrocaseous nodule.

  • Regulation of Sigma Factor Activity

    • Sigma factors are proteins that function in transcription initiation .
    • The activity of sigma factors within a cell is controlled in numerous ways.
    • However, if transcription of genes is not required, sigma factors will not be active.
    • The anti-sigma factors will bind to the RNA polymerase and prevent its binding to sigma factors present at the promoter site.
    • The anti-sigma factors are responsible for regulating inhibition of transcriptional activity in organisms that require sigma factor for proper transcription initiation.