In this article we will discuss about: 1. Heterothallism in Fungi 2. Heterokaryosis in Fungi 3. Parasexuality. Heterothallism in Fungi: A. F. Blakeslee, an American. heterokaryosis The presence in the same cell of two or more genetically different nuclei. Heterokaryosis occurs naturally in certain fungi, in which it results from. Heterokaryosis, the association of genetically diverse nuclei in a system capable of propagation, is a phenomenon peculiar to, but common in, the fungi. During.

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A heterokaryon is a multinucleate cell that contains genetically different nuclei. Heterokaryotic and heterokaryosis are derived terms. This is a special type of syncytium.

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This can occur naturally, such as in the mycelium of fungi during sexual reproduction, or artificially as formed by the experimental fusion of two genetically different cells, as e.

A medical example is a heterokaryon composed of nuclei from Hurler syndrome and Hunter syndrome.

Both of these diseases result in problems in mucopolysaccharide metabolism. However, a heterokaryon of nuclei from both of these diseases exhibits normal mucopolysaccharide metabolism, proving that the two syndromes affect different proteins and so im correct each other in the heterokaryon.


Heterokaryons are found in the life cycle of yeasts, for example Saccharomyces cerevisiae heterokaryosls, a genetic model organism. The heterokaryon stage is produced from the fusion of two haploid cells. This transient heterokaryon can produce further haploid buds, or cell nuclei can fuse and produce a diploid cell, which can then undergo mitosis.

Fungi: Heterothallism, Heterokaryosis and Parasexuality | Biology

The term heterokaryon was coined inindependently by B. Watkins, and by Y. The term was first used for ciliate protozoans such as Tetrahymena. This has two types of cell nuclei, a large, somatic macronucleus and a small, germline micronucleus. Both exist in a single cell at the same time and carry out different functions with distinct cytological and biochemical properties.

Heterokaryon – Wikipedia

Many fungi notably the arbuscular mycorrhizal fungi exhibit heterokaryosis. Heterokaryosis can lead to individuals that have different nuclei in different parts of their mycelium, although in ascomycetes, particularly in ” Neurospora “, nuclei have been shown to flow and mix throughout the mycelium.


Heterokaryosis is most common in fungi, but also occurs in slime molds. This happens because heterokaryosiw nuclei in the ‘plasmodium’ form are the products of many pairwise fusions between amoeboid haploid individuals.

Fungi: Heterothallism, Heterokaryosis and Parasexuality | Biology

When genetically divergent nuclei come together in the plasmodium form, cheaters have been shown to emerge. However, genetic homogeneity among fusing amoeboid serves to maintain the multicellular plasmodium. From Wikipedia, the free encyclopedia. Look up heterokaryon in Wiktionary, the free dictionary. Nonself recognition and heterokaryon incompatibility in filamentous fungi.

A dictionary of genetics. The major transitions in evolution. Retrieved from ” https: Eukaryotic cells Heterokkaryosis Cell biology. Views Read Edit View history. This page was last edited on 8 Augustat By using this site, you agree to the Terms of Use and Privacy Policy.