Spore formation and karyological characterization of basidiosporogenesis, meiosis, post-meiotic and nuclear migration mitosis in Coprinus comatus

ABSTRACT Spores are essential particles for the survival of many organisms, both prokaryotic and eukaryotic. Among the eukaryotes, fungi have developed spores with superior resistance and dispersal properties. For the human fungal pathogens, however, relatively little is known about the role that spores play in dispersal and infection. Here we present the purification and characterization of spores from the environmental fungus Cryptococcus neoformans. For the first time, we purified spores to homogeneity and assessed their morphological, stress resistance, and surface properties. We found that spores are morphologically distinct from yeast cells and are covered with a thick spore coat. Spores are also more resistant to environmental stresses than yeast cells and display a spore-specific configuration of polysaccharides on their surfaces. Surprisingly, we found that the surface of the spore reacts with antibodies to the polysaccharide glucuronoxylomannan, the most abundant component of the polysaccharide capsule required for C. neoformans virulence. We explored the role of capsule polysaccharide in spore development by assessing spore formation in a series of acapsular strains and determined that capsule biosynthesis genes are required for proper sexual development and normal spore formation. Our findings suggest that C. neoformans spores may have an adapted cell surface that facilitates persistence in harsh environments and ultimately allows them to infect mammalian hosts.

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Karyological characterization of meiosis, post-meiotic mitosis and nuclear migration in the ectomycorrhizal fungus Rhizopogon roseolus (= R. rubescens)

Mycologia ◽

10.3852/11-279 ◽

2012 ◽

Vol 104 (5) ◽

pp. 981-987 ◽

Cited By ~ 2

Author(s):

N. Shimomura ◽

K. Sawada ◽

T. Aimi ◽

N. Maekawa ◽

T. Matsumoto

Keyword(s):

Nuclear Migration ◽

Ectomycorrhizal Fungus ◽

Rhizopogon Roseolus

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Extragenic suppressors of a dynein mutation that blocks nuclear migration in Aspergillus nidulans.

Genetics ◽

10.1093/genetics/139.3.1223 ◽

1995 ◽

Vol 139 (3) ◽

pp. 1223-1232 ◽

Cited By ~ 1

Author(s):

G H Goldman ◽

N R Morris

Keyword(s):

Aspergillus Nidulans ◽

Heavy Chain ◽

Nuclear Migration ◽

Cytoplasmic Dynein ◽

Complementation Group ◽

Large Molecular Weight ◽

Weight Protein ◽

Partial Suppression ◽

Extragenic Suppressors

Abstract Cytoplasmic dynein is a large molecular weight protein complex that functions as a microtubule-dependent, negative, end-directed "motor." Mutations in nudA, which encodes the heavy chain of cytoplasmic dynein, inhibit nuclear migration in Aspergillus nidulans. This paper describes the selection and characterization of extragenic suppressors of the nudA1 mutation preparatory to the identification of other proteins that interact directly or indirectly with the cytoplasmic dynein heavy chain. To facilitate future cloning of the suppressor genes, we have searched particularly for extragenic suppressor mutations that also convey a selectable phenotype, such as cold or dimethyl sulfoxide sensitivity. Genetic analysis of 16 revertants has defined at least five extragenic suppressors of nudA1 (snaA-E). All the sna mutations except one were recessive in diploids homozygous for nudA1 and heterozygous for sna mutations. To characterize the nuclear migration phenotype in the sna mutants, conidia of one representative of each complementation group were germinated, fixed and nuclei stained. The sna mutants display partial suppression of the nudA1 nuclear migration defect. Although conidiophores were produced in the sna mutants, they failed to develop normally and to produce spores. Examination of the nudA1,sna conidiophores under the microscope showed that nuclear migration into the metulae and phialides was defective.

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Characterization of a clinical Clostridioides difficile isolate with markedly reduced fidaxomicin susceptibility and a V1143D mutation in rpoB

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dky375 ◽

2018 ◽

Vol 74 (1) ◽

pp. 6-10 ◽

Cited By ~ 9

Author(s):

Julian Schwanbeck ◽

Thomas Riedel ◽

Friederike Laukien ◽

Isabel Schober ◽

Ines Oehmig ◽

...

Keyword(s):

Single Molecule ◽

Sequence Data ◽

Normal Growth ◽

Amplicon Sequencing ◽

Spore Formation ◽

Compensatory Mechanisms ◽

Toxin A ◽

Clostridioides Difficile

Abstract Objectives The identification and characterization of clinical Clostridioides difficile isolates with reduced fidaxomicin susceptibility. Methods Agar dilution assays were used to determine fidaxomicin MICs. Genome sequence data were obtained by single-molecule real-time (SMRT) sequencing in addition to amplicon sequencing of rpoB and rpoC alleles. Allelic exchange was used to introduce the identified mutation into C. difficile 630Δerm. Replication rates, toxin A/B production and spore formation were determined from the strain with reduced fidaxomicin susceptibility. Results Out of 50 clinical C. difficile isolates, isolate Goe-91 revealed markedly reduced fidaxomicin susceptibility (MIC >64 mg/L). A V1143D mutation was identified in rpoB of Goe-91. When introduced into C. difficile 630Δerm, this mutation decreased fidaxomicin susceptibility (MIC >64 mg/L), but was also associated with a reduced replication rate, low toxin A/B production and markedly reduced spore formation. In contrast, Goe-91, although also reduced in toxin production, showed normal growth rates and only moderately reduced spore formation capacities. This indicates that the rpoBV1143D allele-associated fitness defect is less pronounced in the clinical isolate. Conclusions To the best of our knowledge, this is the first description of a pathogenic clinical C. difficile isolate with markedly reduced fidaxomicin susceptibility. The lower-than-expected fitness burden of the resistance-mediating rpoBV1143D allele might be an indication for compensatory mechanisms that take place during in vivo selection of mutants.

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Isolation and characterization of heavy-metal-mobilizing bacteria from contaminated soils and their potential in promoting Pb, Cu, and Cd accumulation by Coprinus comatus

Canadian Journal of Microbiology ◽

10.1139/w11-110 ◽

2012 ◽

Vol 58 (1) ◽

pp. 45-53 ◽

Cited By ~ 14

Author(s):

Xiao-bing Jing ◽

Nan He ◽

Ying Zhang ◽

Yan-ru Cao ◽

Heng Xu

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Contaminated Soils ◽

Bacillus Sp ◽

Cd Accumulation ◽

Treated Soil ◽

Coprinus Comatus ◽

Leading Role ◽

Isolation And Characterization

The enhanced effect of heavy-metal-mobilizing bacteria on the uptake of Pb, Cu, and Cd by Coprinus comatus from Pb-, Cu-, and Cd-multicontaminated soil was assessed in this study. Thirteen strains, tolerating 800 mg·L–1 Pb, 200 mg·L–1 Cu, and 200 mg·L–1 Cd simultaneously were selected for heavy-metal-solubilizing experiments in soil. The mobilization of heavy metals depended on the characteristics of bacteria and heavy metals. Correlation analysis demonstrated that for Pb solubilization, the acid-producing ability was the most significant factor, while for Cu and Cd, siderophores played a leading role in this process. Four strains, based on their excellent ability to solubilize heavy metal in soil, were applied in pot experiments. The results showed that all strains can promote the growth of C. comatus and meanwhile help mushroom accumulate more heavy metals (Pb, Cd, and Cu). The maximum uptake for total Pb and Cu by C. comatus was observed in inoculations with Bacillus sp. strain JSG1 (2.02- and 2.13-fold, respectively, compared with uninoculated soil), while for Cd, it was recorded in Bacillus sp. strain PB2 treated soil (2.03-fold). Therefore, this work suggests that the mushroom–bacteria interaction can be developed into a novel bioremediation strategy.

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