Chapter 25
Hybridization and Its Importance in the Cryptococcus Species Complex
Massimo Cogliati,
Xiaorong Lin,
Maria Anna Viviani,
Massimo Cogliati
Laboratory of Medical Mycology, Department of Public Health – Microbiology – Virology, Universitá degli Studi di Milano, 20133 Milano, Italy
Search for more papers by this authorXiaorong Lin
Department of Biology, Texas A&M University, College Station, TX, 77843
Search for more papers by this authorMaria Anna Viviani
Laboratory of Medical Mycology, Department of Public Health – Microbiology – Virology, Universitá degli Studi di Milano, 20133 Milano, Italy
Search for more papers by this authorMassimo Cogliati,
Xiaorong Lin,
Maria Anna Viviani,
Massimo Cogliati
Laboratory of Medical Mycology, Department of Public Health – Microbiology – Virology, Universitá degli Studi di Milano, 20133 Milano, Italy
Search for more papers by this authorXiaorong Lin
Department of Biology, Texas A&M University, College Station, TX, 77843
Search for more papers by this authorMaria Anna Viviani
Laboratory of Medical Mycology, Department of Public Health – Microbiology – Virology, Universitá degli Studi di Milano, 20133 Milano, Italy
Search for more papers by this authorBook Editor(s):Joseph Heitman,
Thomas R. Kozel,
Kyung J. Kwon-Chung,
John R. Perfect,
Arturo Casadevall,
Joseph Heitman
Duke University Medical Center, Durham, NC, 27710
Search for more papers by this authorThomas R. Kozel
University of Nevada School of Medicine, Reno, NV, 89557-0320
Search for more papers by this authorKyung J. Kwon-Chung
National Institute of Allergy and Infectious Diseases, Bethesda, MD, 20892
Search for more papers by this authorJohn R. Perfect
Duke University Medical Center, Durham, NC, 27710
Search for more papers by this authorArturo Casadevall
Albert Einstein College of Medicine, Bronx, NY, 10461
Search for more papers by this authorFirst published: 12 November 2010
Summary
A study on the identification of hybrids identified six distinct clusters based on the genotypes of a large number of Cryptococcus neoformans and Cryptococcus gattii global isolates using amplified fragment length polymorphism (AFLP). A combination of genotype and ploidy analyses are able to discriminate AD hybrids from haploid serotype A or D isolates. Serological reactions and a set of genotyping techniques have been used to determine the serotype of Cryptococcus strains. Serotype A strains presented a rim pattern characterized by a sharp increase in the optical gradient at the capsular edge followed directly by an immediate decrease. The estimation of the time of hybridization showed that recombination occurred very recently, indicating that hybridization is important during Cryptococcus evolution. Gene genealogical analysis supported the hypothesis of multiple origins of hybrid strains, suggesting that hybridization events occurred in different times probably coinciding with the continuing dispersion of C. neoformans in the environment that allows the contact between genetic divergent populations. In conclusion, hybridization, in addition to a low rate of sexual reproduction, represents an important mechanism for Cryptococcus to introduce genetic variants in a population with a prevalent clonal expansion.
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