Clonal Reproduction and Limited Dispersal in an Environmental Population of Cryptococcus neoformans var. gattii Isolates from Australia

Abstract

Cryptococcus neoformans var. gattii is a causative agent of cryptococcosis and is thought to have a specific ecological association with a number of Eucalyptus species in Australia. However, the role that the tree plays in the life cycle of the fungus and the nature of the infectious propagule are not well understood. This study set out to examine whether sexual recombination is occurring in a natural population of C. neoformans var. gattii and whether the fungus disseminates between colonized trees. Thirty C. neoformans var. gattii isolates, consisting of both the ␣ and a mating types, were collected from 13 Eucalyptus camaldulensis trees growing along a riverbank in Renmark, South Australia. The genetic diversity within the population was studied by using amplified fragment length polymorphism fingerprinting, and each isolate was assigned a unique multilocus genotype. Population genetic analyses of the multilocus data found no evidence of genetic exchange between members of the population, indicating a clonal population structure. Canonical variate analysis was then used to study the relationship between isolates from different colonized trees. Isolates from individual trees were strongly correlated, and it appeared that dispersal between trees was not occurring to any appreciable extent. These results suggest that the eucalypt may not be the primary niche for C. neoformans var. gattii but that the decaying wood present in hollows on these trees may provide a favorable substrate for extensive clonal propagation of the yeast cells.

Patterns of within population dispersal and mating of the fungus Microbotryum violaceum parasitising the plant Silene latifolia

“…Strong interpopulation differentiation was found, as reported in previous studies on M. violaceum (Delmotte et al, 1999;Bucheli et al, 2001) and in several examples from other parasites (Blouin et al, 1995;Garcia et al, 2002;Halliday and Carter, 2003;. Strong interpopulation differentiation suggests low migration rates, which is unsurprising for parasites with restricted dispersal.…”

“…However, despite its importance, few empirical studies have examined parasite dispersal. Those that have usually reported strong isolation between populations of parasites (Blouin et al, 1995;Delmotte et al, 1999;Garcia et al, 2002;Halliday and Carter, 2003;. Within-population dispersal is even more rarely investigated in parasites.…”

Aislamiento de Cryptococcus gattii serotipo B a partir de detritos de Eucalyptus spp. en Colombia.

“…Primero se realizó la PCR para la amplificación del gen de la feromona α y en aquellos aislamientos que no amplificaron se realizó la PCR para amplificar el gen de la feromona a. Las condiciones de la PCR para la amplificación del gen de la feromona α, para un volumen final de 50 µl, fueron: 1X de tampón de PCR, 200 mM de cada dNTP, 15 mM de MgCl 2 , 0,2 µm de cada iniciador, 2,5 U de Taq polimerasa (Invitrogen) y 1 µl de ADN (extraído por la técnica de ebullición o por la técnica de extracción con perlas de vidrio) (25,27,28). Para la amplificación del gen de la feromona a se emplearon las condiciones anteriormente descritas, excepto que la concentración de los iniciadores fue de 50 ng/ml (26).…”

“…Abstracts, Sixth International Conference in Cryptococcus and Cryptococcosis, Boston, Massachusetts, June [24][25][26][27][28]2005. Abstract E5).…”

Determinación in vitro de la pareja sexual en aislamientos del complejo Cryptococcus neoformans

“…However, the determination of the mating ability in vitro is associated with a number of problems, like the fact that mating is sensitive to a variety of environmental conditions, including temperature, nutrient availability, and moisture levels (1), and many strains, loose their ability to mate after being extensively manipulated (16). Despite these problems, the determination of the mating potential in vitro is of great interest because sexual recombination is important for the dissemination and propagation of the fungus in the environment and its transition into humans and animals (21).…”