scholarly journals Isolates of Cryptococcus neoformans from Infected Animals Reveal Genetic Exchange in Unisexual, α Mating Type Populations

2008 ◽  
Vol 7 (10) ◽  
pp. 1771-1780 ◽  
Author(s):  
Tien Bui ◽  
Xiaorong Lin ◽  
Richard Malik ◽  
Joseph Heitman ◽  
Dee Carter
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Fungal Pathogens ◽  
Genetic Recombination ◽  
Genetic Exchange ◽  
Pathogenic Yeast ◽  
Asexual Propagation ◽  
Sexual Recombination ◽  
Single Mating ◽  
Almost All

ABSTRACT Sexual reproduction and genetic exchange are important for the evolution of fungal pathogens and for producing potentially infective spores. Studies to determine whether sex occurs in the pathogenic yeast Cryptococcus neoformans var. grubii have produced enigmatic results, however: basidiospores are the most likely infective propagules, and clinical isolates are fertile and genetically diverse, consistent with a sexual species, but almost all populations examined consist of a single mating type and have little evidence for genetic recombination. The choice of population is critical when looking for recombination, particularly when significant asexual propagation is likely and when latency may complicate assessing the origin of an isolate. We therefore selected isolates from infected animals living in the region of Sydney, Australia, with the assumption that the relatively short life spans and limited travels of the animal hosts would provide a very defined population. All isolates were mating type α and were of molecular genotype VNI or VNII. A lack of linkage disequilibrium among loci suggested that genetic exchange occurred within both genotype groups. Four diploid VNII isolates that produced filaments and basidium-like structures when cultured in proximity to an a mating type strain were found. Recent studies suggest that compatible α-α unions can occur in C. neoformans var. neoformans populations and in populations of the sibling species Cryptococcus gattii. As a mating type strains of C. neoformans var. grubii have never been found in Australia, or in the VNII molecular type globally, the potential for α-α unions is evidence that α-α unisexual mating maintains sexual recombination and diversity in this pathogen and may produce infectious propagules.

scholarly journals Presence of α and a Mating Types in Environmental and Clinical Collections of Cryptococcus neoformans var. gattii Strains from Australia

1999 ◽  
Vol 37 (9) ◽  
pp. 2920-2926 ◽  
Author(s):  
C. L. Halliday ◽  
T. Bui ◽  
M. Krockenberger ◽  
R. Malik ◽  
D. H. Ellis ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Causative Agent ◽  
Pcr Primers ◽  
Mating Types ◽  
Limited Data ◽  
Environmental Isolates ◽  
Specific Pcr ◽  
Sexual Recombination ◽  
Mating Type Genes

Cryptococcus neoformans var. gattii lives in association with certain species of eucalyptus trees and is a causative agent of cryptococcosis. It exists as two mating types, MATα and MATa, which is determined by a single-locus, two-allele system. In the closely related C. neoformansvar. neoformans, the α mating type has been found to outnumber its a counterpart by at least 30:1, but there have been very limited data on the proportions of each mating type in C. neoformans var. gattii. In the present study, specific PCR primers were designed to amplify two separate α-mating-type genes from C. neoformans var.gattii strains. These were used to survey for the presence of the two mating types in clinical and environmental collections ofC. neoformans var. gattii strains from Australia. Sixty-eight of 69 clinical isolates produced both α mating type-specific bands and were assumed to be of the α mating type. The majority of environmental isolates were also of the α mating type, but the a mating type was located in two separate areas. In one area, the a mating type outnumbered the α mating type by 27:2, but in the second area, the ratio of the two mating types was close to the 50:50 ratio expected for sexual recombination.

scholarly journals Mitochondria Are Inherited From the MATa Parent in Crosses of the Basidiomycete Fungus Cryptococcus neoformans

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1315-1325 ◽  
Author(s):  
Zhun Yan ◽  
Jianping Xu
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Clinical Strain ◽  
Pathogenic Yeast ◽  
Type Locus ◽  
Mating Type Locus ◽  
Mtdna Inheritance ◽  
Mitochondrial Genotype ◽  
Diploid Cells ◽  
Isogenic Strains

Abstract Previous studies demonstrated that mitochondrial DNA (mtDNA) was uniparentally transmitted in laboratory crosses of the pathogenic yeast Cryptococcus neoformans. To begin understanding the mechanisms, this study examined the potential role of the mating-type locus on mtDNA inheritance in C. neoformans. Using existing isogenic strains (JEC20 and JEC21) that differed only at the mating-type locus and a clinical strain (CDC46) that possessed a mitochondrial genotype different from JEC20 and JEC21, we constructed strains that differed only in mating type and mitochondrial genotype. These strains were then crossed to produce hyphae and sexual spores. Among the 206 single spores analyzed from six crosses, all but one inherited mtDNA from the MATa parents. Analyses of mating-type alleles and mtDNA genotypes of natural hybrids from clinical and natural samples were consistent with the hypothesis that mtDNA is inherited from the MATa parent in C. neoformans. To distinguish two potential mechanisms, we obtained a pair of isogenic strains with different mating-type alleles, mtDNA types, and auxotrophic markers. Diploid cells from mating between these two strains were selected and 29 independent colonies were genotyped. These cells did not go through the hyphal stage or the meiotic process. All 29 colonies contained mtDNA from the MATa parent. Because no filamentation, meiosis, or spore formation was involved in generating these diploid cells, our results suggest a selective elimination of mtDNA from the MATα parent soon after mating. To our knowledge, this is the first demonstration that mating type controls mtDNA inheritance in fungi.

scholarly journals Microsatellite and Chromosome Evolution of Parthenogenetic Sitobion Aphids in Australia

Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 747-756 ◽  
Author(s):  
Paul Sunnucks ◽  
Phillip R England ◽  
Andrea C Taylor ◽  
Dinah F Hales
Keyword(s):  
Sexual Reproduction ◽  
Chromosome Evolution ◽  
Genetic Recombination ◽  
Allelic Variation ◽  
Repeat Unit ◽  
Chromosomal Evolution ◽  
Microsatellite Variation ◽  
Wide Range ◽  
Sexual Recombination ◽  
Minimum Numbers

Abstract Single-locus microsatellite variation correlated perfectly with chromosome number in Sitobion miscanthi aphids. The microsatellites were highly heterozygous, with up to 10 alleles per locus in this species. Despite this considerable allelic variation, only seven different S. miscanthi genotypes were discovered in 555 individuals collected from a wide range of locations, hosts and sampling periods. Relatedness between genotypes suggests only two successful colonizations of Australia. There was no evidence for genetic recombination in 555 S. miscanthi so the occurrence of recent sexual reproduction must be near zero. Thus diversification is by mutation and chromosomal rearrangement alone. Since the aphids showed no sexual recombination, microsatellites can mutate without meiosis. Five of seven microsatellite differences were a single repeat unit, and one larger jump is likely. The minimum numbers of changes between karyotypes corresponded roughly one-to-one with microsatellite allele changes, which suggests very rapid chromosomal evolution. A chromosomal fission occurred in a cultured line, and a previously unknown chromosomal race was detected. All 121 diverse S. near fragariae were heterozygous but revealed only one genotype. This species too must have a low rate of sexual reproduction and few colonizations of Australia.

scholarly journals Investigation of Antifungal Mechanisms of Thymol in the Human Fungal Pathogen, Cryptococcus neoformans

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3476
Author(s):  
Kwang-Woo Jung ◽  
Moon-Soo Chung ◽  
Hyoung-Woo Bai ◽  
Byung Yeoup Chung ◽  
Sungbeom Lee
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogens ◽  
Reverse Genetics ◽  
Mapk Pathway ◽  
Global Climate ◽  
Mitogen Activated Protein Kinase ◽  
Ergosterol Biosynthesis ◽  
Thymus Vulgaris ◽  
Dependent Manner ◽  
Expression Levels

Due to lifespan extension and changes in global climate, the increase in mycoses caused by primary and opportunistic fungal pathogens is now a global concern. Despite increasing attention, limited options are available for the treatment of systematic and invasive mycoses, owing to the evolutionary similarity between humans and fungi. Although plants produce a diversity of chemicals to protect themselves from pathogens, the molecular targets and modes of action of these plant-derived chemicals have not been well characterized. Using a reverse genetics approach, the present study revealed that thymol, a monoterpene alcohol from Thymus vulgaris L., (Lamiaceae), exhibits antifungal activity against Cryptococcus neoformans by regulating multiple signaling pathways including calcineurin, unfolded protein response, and HOG (high-osmolarity glycerol) MAPK (mitogen-activated protein kinase) pathways. Thymol treatment reduced the intracellular concentration of Ca2+ by controlling the expression levels of calcium transporter genes in a calcineurin-dependent manner. We demonstrated that thymol decreased N-glycosylation by regulating the expression levels of genes involved in glycan-mediated post-translational modifications. Furthermore, thymol treatment reduced endogenous ergosterol content by decreasing the expression of ergosterol biosynthesis genes in a HOG MAPK pathway-dependent manner. Collectively, this study sheds light on the antifungal mechanisms of thymol against C. neoformans.

Comparative gene genealogical analyses of strains of serotype AD identify recombination in populations of serotypes A and D in the human pathogenic yeast Cryptococcus neoformans

Microbiology ◽  
2003 ◽  
Vol 149 (8) ◽  
pp. 2147-2154 ◽  
Author(s):  
Jianping Xu ◽  
Thomas G. Mitchell
Keyword(s):  
Monoclonal Antibodies ◽  
Cryptococcus Neoformans ◽  
Natural Populations ◽  
The Other ◽  
Pathogenic Yeast ◽  
Gene Genealogy ◽  
Serotype A ◽  
The World ◽  
Significant Divergence ◽  
Allelic Group

Cryptococcus neoformans is a major pathogen of humans throughout the world. Using commercial monoclonal antibodies to capsular epitopes, strains of C. neoformans manifest five serotypes: A, B, C, D and AD. Previous studies demonstrated significant divergence among serotypes A, B, C and D, which are typically haploid. In contrast, most strains of serotype AD are diploid or aneuploid and result from recent hybridization between strains of serotypes A and D. Whether serotypes A, B, C and D represent strictly asexual lineages is not known. Using comparative genealogical analyses of two genes, the authors investigated whether recombination occurred among strains within serotypes A and D. For each of 14 serotype AD strains, a portion (642 bp) of the orotidine monophosphate pyrophosphorylase (URA5) gene was cloned and sequenced. Each of these 14 strains contained two different alleles and sequences for both alleles were obtained. The URA5 gene genealogy was compared to that derived from the laccase (LAC) gene, which was reported recently for the same 14 strains. For both genes, each of the 14 serotype AD strains contained two phylogenetically distinct alleles: one allele was highly similar to those from serotype A strains and the other to alleles from serotype D strains. However, within both the serotype A allelic group and the serotype D allelic group, there was significant incongruence between genealogies derived from URA5 and LAC. The results suggest recombination in natural populations of both serotypes A and D.

GENETIC RECOMBINATION IN SEXUAL CROSSES OF PHYCOMYCES

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 445-462
Author(s):  
A P Eslava ◽  
M I Alvarez ◽  
Patricia V Burke ◽  
M Delbrück
Keyword(s):  
Mating Type ◽  
Genetic Recombination ◽  
Recombination Frequency ◽  
Intragenic Recombination ◽  
Phycomyces Blakesleeanus ◽  
Sexual Crosses ◽  
Color Marker ◽  
Three Factor

ABSTRACT Sexual crosses between strains of Phycomyces blakesleeanus, involving three auxotrophic and one color marker and yielding a high proportion of zygospore germination, are described. Samples of 20-40 germ spores from 311 individual fertile germ sporangia originating from five two-factor and three three-factor crosses were characterized. The results show: (1) absence of any contribution of apogamic nuclei to the progeny, (2) confirmation of Burgeff's conjecture that the germ spores of any germ sporangium in most cases derive from one meiosis. In a cross involving two allelic markers the analysis of 175 pooled germ sporangia suggests an intragenic recombination frequency of 0.6%. All other factor combinations tested are unlinked. The bulk of the germ spores are homokaryotic. However, a small portion (4%) are heterokaryotic with respect to mating type.

The alpha-mating type locus of Cryptococcus neoformans contains a peptide pheromone gene

1993 ◽  
Vol 13 (3) ◽  
pp. 1962-1970
Author(s):  
T D Moore ◽  
J C Edman
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Cell Types ◽  
Yeast Cells ◽  
Mating Types ◽  
Type Locus ◽  
Reading Frame ◽  
Cloning Method ◽  
Opportunistic Fungal Pathogen ◽  
Specific Fragment

The opportunistic fungal pathogen Cryptococcus neoformans has two mating types, MATa and MAT alpha. The MAT alpha strains are more virulent. Mating of opposite mating type haploid yeast cells results in the production of a filamentous hyphal phase. The MAT alpha locus has been isolated in this study in order to identify the genetic differences between mating types and their contribution to virulence. A 138-bp fragment of MAT alpha-specific DNA which cosegregates with alpha-mating type was isolated by using a difference cloning method. Overlapping phage and cosmid clones spanning the entire MAT alpha locus were isolated by using this MAT alpha-specific fragment as a probe. Mapping of these clones physically defined the MAT alpha locus to a 35- to 45-kb region which is present only in MAT alpha strains. Transformation studies with fragments of the MAT alpha locus identified a 2.1-kb XbaI-HindIII fragment that directs starvation-induced filament formation in MATa cells but not in MAT alpha cells. This 2.1-kb fragment contains a gene, MF alpha, with a small open reading frame encoding a pheromone precursor similar to the lipoprotein mating factors found in Saccharomyces cerevisiae, Ustilago maydis, and Schizosaccharomyces pombe. The ability of the MATa cells to express, process, and secrete the MAT alpha pheromone in response to starvation suggests similar mechanisms for these processes in both cell types. These results also suggest that the production of pheromone is under a type of nutritional control shared by the two cell types.

scholarly journals Genotyping, serotyping and determination of mating-type of Cryptococcus neoformans clinical isolates from São Paulo State, Brazil

2007 ◽  
Vol 49 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Marcelo Teruyuki Matsumoto ◽  
Ana Marisa Fusco-Almeida ◽  
Lilian Cristiane Baeza ◽  
Márcia de Souza Carvalho Melhem ◽  
Maria José Soares Medes-Giannini
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Rflp Analysis ◽  
Sao Paulo ◽  
Clinical Isolates ◽  
São Paulo ◽  
Paulo State ◽  
Pcr Fingerprinting ◽  
Pcr Rflp ◽  
São Paulo State

The basidiomycetous yeast Cryptococcus neoformans is an important fungal pathogen mainly in immunocompromised patients. In this study, 47 clinical isolates of C. neoformans from regions of São Paulo State were studied serologically by using the Crypto Check Iatron RM 304-K kit, their genetic diversity was estimated by PCR-fingerprinting with a microsatellite-specific sequence (GACA)4, RAPD with primer 6 (Amersham Pharmacia Biotech), PCR-restriction fragment length polymorphism (RFLP) analysis of the phospholipase B gene (PLB1) digested with AvaI and mating type analysis by PCR. All 47 strains isolated from HIV positive patients included in this study were serotype A and MATalpha. The majority of the isolates (45/47) were VNI and only two were VNII by PCR-fingerprinting and PCR-RFLP analysis. High degree of homogeneity was observed when (GACA)4 was used, being highly correlated (> 0.9). In contrast, the RAPD analysis was more heterogeneous with higher number of molecular profiles. By PCR-RFLP, no new molecular type was found, enhancing the suggestion that the differences based on conserved gene as PLB1, can be resultant of ongoing divergent evolution within the C. neoformans complex, into the current eight subtypes. Our results furnish new information on the molecular epidemiology of C. neoformans in the southeast region of Brazil.

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