scholarly journals Clinical and Environmental Isolates of Cryptococcus gattii from Australia That Retain Sexual Fecundity

2005 ◽  
Vol 4 (8) ◽  
pp. 1410-1419 ◽  
Author(s):  
Leona T. Campbell ◽  
James A. Fraser ◽  
Connie B. Nichols ◽  
Fred S. Dietrich ◽  
Dee Carter ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Dominant Mode ◽  
Cryptococcus Gattii ◽  
Sexual Cycle ◽  
Environmental Isolates ◽  
Molecular Type ◽  
Pathogenic Yeast ◽  
Cycle Dependent ◽  
Mat Locus ◽  
First Time

ABSTRACTCryptococcus gattiiis a primary pathogenic yeast that causes disease in both animals and humans. It is closely related toCryptococcus neoformansand diverged from a common ancestor ∼40 million years ago. WhileC. gattiihas a characterized sexual cycle dependent upon a dimorphic region of the genome known as the MAT locus, mating has rarely been observed in this species. In this study, we identify for the first time clinical (both human and veterinary) and environmental isolates from Australia that retain sexual fecundity. A collection of 120 isolates from a variety of geographic locations was analyzed for molecular type, mating type, and the ability to develop mating structures when cocultured with fertile tester strains. Nine isolates produced dikaryotic filaments with paired nuclei, fused clamp connections, and basidiospores. DNA sequence analysis of three genes (URA5, the MATα-specificSXI1α gene, and the MATa-specificSXI2agene) revealed little or no variability inURA5andSXI2a, respectively. However across the 108 MATα strains sequenced, theSXI1α gene was found to exist as 11 different alleles. Phylogenetic analysis found most variation to occur in the more fertile genotypes. Although some lineages of AustralianC. gattiihave retained the ability to mate, the majority of isolates were sterile, suggesting that asexuality is the dominant mode of propagation in these populations.

scholarly journals First Report of blaNDM-1 Bearing IncX3 Plasmid in Clinically Isolated ST11 Klebsiella pneumoniae from Pakistan

2021 ◽  
Vol 9 (5) ◽  
pp. 951
Author(s):  
Hazrat Bilal ◽  
Gaojian Zhang ◽  
Tayyab Rehman ◽  
Jianxion Han ◽  
Sabir Khan ◽  
...  
Keyword(s):  
Sequence Type ◽  
The Other ◽  
High Rate ◽  
Antibiotics Resistance ◽  
New Delhi ◽  
Molecular Type ◽  
Plasmid Analysis ◽  
First Time ◽  
Encoding Genes ◽  
Sequence Types

The New Delhi Metallo-β-lactamase (NDM) is among the most threatening forms of carbapenemases produced by K. pneumoniae, well-known to cause severe worldwide infections. The molecular epidemiology of blaNDM-1-harboring K. pneumoniae is not well elucidated in Pakistan. Herein, we aim to determine the antibiotics-resistance profile, genes type, molecular type, and plasmid analysis of 125 clinically isolated K. pneumoniae strains from urine samples during July 2018 to January 2019 in Pakistan. A total of 34 (27.2%) K. pneumoniae isolates were carbapenemases producers, and 23 (18.4%) harbored the blaNDM-1 gene. The other carbapenemases encoding genes, i.e., blaIMP-1 (7.2%), blaVIM-1 (3.2%), and blaOXA-48 (2.4%) were also detected. The Multi Locus Sequence Typing (MLST) results revealed that all blaNDM-1-harboring isolates were ST11. The other sequence types detected were ST1, ST37, and ST105. The cluster analysis of Xbal Pulsed Field Gel Electrophoresis (PFGE) revealed variation amongst the clusters of the identical sequence type isolates. The blaNDM-1 gene in all of the isolates was located on a 45-kb IncX3 plasmid, successfully transconjugated. For the first time, blaNDM-1-bearing IncX3 plasmids were identified from Pakistan, and this might be a new primary vehicle for disseminating blaNDM-1 in Enterobacteriaceae as it has a high rate of transferability.

scholarly journals Transcription Factor STE12α Has Distinct Roles in Morphogenesis, Virulence, and Ecological Fitness of the Primary Pathogenic Yeast Cryptococcus gattii

2006 ◽  
Vol 5 (7) ◽  
pp. 1065-1080 ◽  
Author(s):  
Ping Ren ◽  
Deborah J. Springer ◽  
Melissa J. Behr ◽  
William A. Samsonoff ◽  
Sudha Chaturvedi ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Gene Knockout ◽  
Natural Habitat ◽  
Cryptococcus Gattii ◽  
Human Neutrophils ◽  
Knockout Mutant ◽  
Pathogenic Yeast ◽  
Ecological Fitness

ABSTRACT Cryptococcus gattii is a primary pathogenic yeast, increasingly important in public health, but factors responsible for its host predilection and geographical distribution remain largely unknown. We have characterized C. gattii STE12α to probe its role in biology and pathogenesis because this transcription factor has been linked to virulence in many human and plant pathogenic fungi. A full-length STE12α gene was cloned by colony hybridization and sequenced using primer walk and 3′ rapid amplification of cDNA ends strategies, and a ste12αΔ gene knockout mutant was created by URA5 insertion at the homologous site. A semiquantitative analysis revealed delayed and poor mating in ste12αΔ mutant; this defect was not reversed by exogenous cyclic AMP. C. gattii parent and mutant strains showed robust haploid fruiting. Among putative virulence factors tested, the laccase transcript and enzymatic activity were down regulated in the ste12αΔ mutant, with diminished production of melanin. However, capsule, superoxide dismutase, phospholipase, and urease were unaffected. Similarly, Ste12 deficiency did not cause any auxotrophy, assimilation defects, or sensitivity to a large panel of chemicals and antifungals. The ste12αΔ mutant was markedly attenuated in virulence in both BALB/c and A/Jcr mice models of meningoencephalitis, and it also exhibited significant in vivo growth reduction and was highly susceptible to in vitro killing by human neutrophils (polymorphonuclear leukocytes). In tests designed to simulate the C. gattii natural habitat, the ste12αΔ mutant was poorly pigmented on wood agar prepared from two tree species and showed poor survival and multiplication in wood blocks. Thus, STE12α plays distinct roles in C. gattii morphogenesis, virulence, and ecological fitness.

scholarly journals Azole Resistance in Clinical and Environmental Aspergillus Isolates from the French West Indies (Martinique)

2021 ◽  
Vol 7 (5) ◽  
pp. 355
Author(s):  
Lorra Monpierre ◽  
Nicole Desbois-Nogard ◽  
Isabel Valsecchi ◽  
Marielle Bajal ◽  
Cécile Angebault ◽  
...  
Keyword(s):  
West Indies ◽  
Culture Media ◽  
Antifungal Susceptibility ◽  
Resistance Mechanisms ◽  
Clinical Samples ◽  
Azole Resistance ◽  
Environmental Isolates ◽  
French West Indies ◽  
First Time ◽  
Microdilution Broth

The emergence of azole resistant Aspergillus spp., especially Aspergillus fumigatus, has been described in several countries around the world with varying prevalence depending on the country. To our knowledge, azole resistance in Aspergillus spp. has not been reported in the West Indies yet. In this study, we investigated the antifungal susceptibility of clinical and environmental isolates of Aspergillus spp. from Martinique, and the potential resistance mechanisms associated with mutations in cyp51A gene. Overall, 208 Aspergillus isolates were recovered from clinical samples (n = 45) and environmental soil samples (n = 163). They were screened for resistance to azole drugs using selective culture media. The Minimum Inhibitory Concentrations (MIC) towards voriconazole, itraconazole, posaconazole and isavuconazole, as shown by the resistant isolates, were determined using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) microdilution broth method. Eight isolates (A. fumigatus, n = 6 and A. terreus, n = 2) had high MIC for at least one azole drug. The sequencing of cyp51A gene revealed the mutations G54R and TR34/L98H in two A. fumigatus clinical isolates. Our study showed for the first time the presence of azole resistance in A. fumigatus and A. terreus isolates in the French West Indies.

An abundant high-mobility-group-like protein is targeted to micronuclei in a cell cycle-dependent and developmentally regulated fashion in Tetrahymena thermophila

1993 ◽  
Vol 13 (1) ◽  
pp. 163-173
Author(s):  
T Wang ◽  
C D Allis
Keyword(s):  
Cell Cycle ◽  
Tetrahymena Thermophila ◽  
Polyclonal Antibodies ◽  
Dna Recombination ◽  
High Mobility ◽  
High Mobility Group ◽  
Sexual Cycle ◽  
Developmentally Regulated ◽  
Early Stages ◽  
Cycle Dependent

In this report, we have demonstrated for the first time that an abundant high-mobility-group (HMG)-like protein, HMG B, previously thought to be specific to macronuclei in Tetrahymena thermophila, is also present in micronuclei. Biochemical data document the fact that HMG B is extremely labile in micronuclei. Unless extreme precautions are taken during the isolation of nuclei (addition of 1% formaldehyde to the nucleus isolation buffer), HMG B is not detected in micronuclei. Using polyclonal antibodies highly selective for HMG B, immunoblotting and immunofluorescence analyses show that the presence of HMG B in micronuclei is dynamic, correlating well with known periods of micronuclear DNA replication. This is the case not only during the vegetative cell cycle but also during early stages of the sexual cycle, conjugation, when the presence of HMG B in micronuclei is also closely correlated with meiotic DNA recombination and repair. Since micronuclei are transcriptionally inactive during vegetative growth, our data lend support to the idea that HMG B does not function exclusively in the establishment of transcriptionally competent chromatin. However, micronuclei are transcriptionally active during early stages of conjugation. Evidence that HMG B is strongly synthesized and deposited into micronuclei during this stage is presented. Therefore, it is tempting to suggest that HMG B may play an important role in remodeling micronuclear chromatin into an "active," more open configuration. We favor a model wherein HMG B, like other abundant, low-specificity HMG box-containing proteins, functions to wrap DNA, presumably modulating higher-order chromatin structure for a broad range of biological processes, including transcription and replication.

scholarly journals Comparative Gene Genealogies Indicate that Two Clonal Lineages of Cryptococcus gattii in British Columbia Resemble Strains from Other Geographical Areas

2005 ◽  
Vol 4 (10) ◽  
pp. 1629-1638 ◽  
Author(s):  
Sarah E. Kidd ◽  
Hong Guo ◽  
Karen H. Bartlett ◽  
Jianping Xu ◽  
James W. Kronstad
Keyword(s):  
British Columbia ◽  
Population Structure ◽  
Nucleotide Sequence ◽  
Global Scale ◽  
Cryptococcus Gattii ◽  
Temperate Climate ◽  
Molecular Type ◽  
Sequence Comparisons ◽  
The World ◽  
Clonal Population Structure

ABSTRACT Cryptococcus gattii has recently emerged as a pathogen of humans and animals in the temperate climate of Vancouver Island, British Columbia (B.C.). The majority (∼95%) of the isolates from the island belong to the VGII molecular type, and the remainder belong to the VGI molecular type. The goals of this study were to compare patterns of molecular variation among C. gattii isolates from B.C. with those from different areas of the world and to investigate the population structure using a comparative gene genealogy approach. Our results indicate that the C. gattii population in B.C. comprises at least two divergent lineages, corresponding to previously identified VGI and VGII molecular types. The genealogical analysis of strains suggested a predominantly clonal population structure among B.C. isolates, while there was evidence for sexual recombination between different molecular types on a global scale. We found no geographic pattern of strain relationships, and nucleotide sequence comparisons revealed that genotypes among isolates from B.C. were also present among isolates from other areas of the world, indicating extensive strain dispersal. The nucleotide sequence diversity among isolates from B.C. was similar to that among isolates from other areas of the world.

scholarly journals Erratum to: Genotypic Characterization of Environmental Isolates of Cryptococcus gattii from Puerto Rico

2010 ◽  
Vol 170 (4) ◽  
pp. 287-289 ◽  
Author(s):  
Yaliz Loperena-Alvarez ◽  
Ping Ren ◽  
Xiaojiang Li ◽  
Dianna J. Schoonmaker-Bopp ◽  
Alejandro Ruiz ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Cryptococcus Gattii ◽  
Environmental Isolates ◽  
Genotypic Characterization

Australia in the global picture of the molecular epidemiology of Cryptococcus gattii molecular type VGII

2015 ◽  
Vol 36 (2) ◽  
pp. 67 ◽  
Author(s):  
Carolina Firacative ◽  
Kennio Ferreira-Paim ◽  
Luciana Trilles ◽  
David M Engelthaler ◽  
Wieland Meyer
Keyword(s):  
Molecular Epidemiology ◽  
Cryptococcus Gattii ◽  
Molecular Type

scholarly journals Jet-Setting Koalas SpreadCryptococcus gattiiVGII in Australia

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Laura J. Schmertmann ◽  
Patrizia Danesi ◽  
Juan Monroy-Nieto ◽  
Jolene Bowers ◽  
David M. Engelthaler ◽  
...  
Keyword(s):  
Western Australia ◽  
Host Species ◽  
Cryptococcus Gattii ◽  
Genomic Diversity ◽  
Molecular Type ◽  
Phascolarctos Cinereus ◽  
Content Type ◽  
Eastern Australia ◽  
Wide Range ◽  
Sporadic Cases

ABSTRACTCryptococcus gattiimolecular type VGII is one of the etiologic agents of cryptococcosis, a systemic mycosis affecting a wide range of host species. Koalas (Phascolarctos cinereus) exhibit a comparatively high prevalence of cryptococcosis (clinical and subclinical) and nasal colonization, particularly in captivity. In Australia, disease associated withC. gattiiVGII is typically confined to Western Australia and the Northern Territory (with sporadic cases reported in eastern Australia), occupying an enigmatic ecologic niche. A cluster of cryptococcosis in captive koalas in eastern Australia (five confirmed cases, a further two suspected), caused predominantly byC. gattiiVGII, was investigated by surveying for subclinical disease, culturing koala nasal swabs and environmental samples, and genotyping cryptococcal isolates.URA5restriction fragment length polymorphism analysis, multilocus sequence typing (MLST), and whole-genome sequencing (WGS) provided supportive evidence that the transfer of koalas from Western Australia and subsequently between several facilities in Queensland spread VGII into uncontaminated environments and environments in whichC. gattiiVGI was endemic. MLST identified VGII isolates as predominantly sequence type 7, while WGS further confirmed a limited genomic diversity and revealed a basal relationship with isolates from Western Australia. We hypothesize that this represents a founder effect following the introduction of a koala from Western Australia. Our findings suggest a possible competitive advantage forC. gattiiVGII over VGI in the context of this captive koala environment. The ability of koalas to seedC. gattiiVGII into new environments has implications for the management of captive populations and movements of koalas between zoos.IMPORTANCECryptococcus gattiimolecular type VGII is one of the causes of cryptococcosis, a severe fungal disease that is acquired from the environment and affects many host species (including humans and koalas). In Australia, disease caused byC. gattiiVGII is largely confined to western and central northern parts of the country, with sporadic cases reported in eastern Australia. We investigated an unusual case cluster of cryptococcosis, caused predominantly byC. gattiiVGII, in a group of captive koalas in eastern Australia. This research identified that the movements of koalas between wildlife parks, including an initial transfer of a koala from Western Australia, introduced and subsequently spreadC. gattiiVGII in this captive environment. The spread of this pathogen by koalas could also impact other species, and these findings are significant in the implications they have for the management of koala transfers and captive environments.

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