Pathology to vertebrate hosts has emerged repeatedly in the order Ophiostomatales. Occasional infections have been observed in Sporothrix mexicana at a low level of virulence, while the main pathogenic species cluster in a derived clade around S. schenckii s.str. In this paper, phylogeny and epidemiology of the members of this clade were investigated for 99 clinical and 36 environmental strains using four genetic loci, viz. rDNA ITS and partial CAL, TEF1, and TEF3; data are compared with amplified fragment length polymorphism (AFLP) genotyping. The four main species of the pathogenic clade were recognised. The species proved to show high degrees of endemicity, which enabled interpretation of literature data where live material or genetic information is lacking. The clade of four species comprised nine subclusters, which often had limited geographic distribution and were separate from each other in all partitions, suggesting low degrees of interbreeding between populations. In contrast, S. globosa exhibited consistent global distribution of identical AFLP types, suggesting another type of dispersal. Sporothrix brasiliensis is known to be involved in an expanding zoonosis and transmitted by cats, whereas S. globosa infections originated from putrid plant material, causing a sapronosis. Sporothrix schenckii s.str., the most variable species within the clade, also had a plant origin, with ecological similarities to that of S. globosa. A hypothesis was put forward that highly specific conditions in the plant material are required to promote the growth of Sporothrix. Fermented, self-heated plant debris may stimulate the thermodependent yeast-like invasive form of the fungus, which facilitates repeated infection of mammals.

Quinones are widely distributed in nature and exhibit diverse biological or pharmacological activities; however, their biosynthetic machineries are largely unknown. The bibenzoquinone oosporein was first identified from the ascomycete insect pathogen Beauveria bassiana >50 y ago. The toxin can also be produced by different plant pathogenic and endophytic fungi with an array of biological activities. Here, we report the oosporein biosynthetic machinery in fungi, a polyketide synthase (PKS) pathway including seven genes for quinone biosynthesis. The PKS oosporein synthase 1 (OpS1) produces orsellinic acid that is hydroxylated to benzenetriol by the hydroxylase OpS4. The intermediate is oxidized either nonenzymatically to 5,5′-dideoxy-oosporein or enzymatically to benzenetetrol by the putative dioxygenase OpS7. The latter is further dimerized to oosporein by the catalase OpS5. The transcription factor OpS3 regulates intrapathway gene expression. Insect bioassays revealed that oosporein is required for fungal virulence and acts by evading host immunity to facilitate fungal multiplication in insects. These results contribute to the known mechanisms of quinone biosynthesis and the understanding of small molecules deployed by fungi that interact with their hosts.

Summary Recent discoveries of novel systemic fungal pathogens with thermally dimorphic yeast-like phases have challenged the current taxonomy of the Ajellomycetaceae, a family currently comprising the genera Blastomyces, Emmonsia, Emmonsiellopsis, Helicocarpus, Histoplasma, Lacazia and Paracoccidioides. Our morphological, phylogenetic and phylogenomic analyses demonstrated species relationships and their specific phenotypes, clarified generic boundaries and provided the first annotated genome assemblies to support the description of two new species. A new genus, Emergomyces, accommodates Emmonsia pasteuriana as type species, and the new species Emergomyces africanus, the etiological agent of case series of disseminated infections in South Africa. Both species produce small yeast cells that bud at a narrow base at 37 °C and lack adiaspores classically associated with the genus Emmonsia. Another novel dimorphic pathogen, producing broad-based budding cells at 37 °C and occurring outside North America, proved to belong to the genus Blastomyces, and is described as Blastomyces percursus.

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The family Ajellomycetaceae (Onygenales) includes mammal-associated pathogens within the genera Blastomyces, Emmonsia, Histoplasma and Paracoccidioides, as well as the recently described genera, Emergomyces that causes disease in immunocompromised hosts, and Emmonsiellopsis, known only from soil. To further assess the phylogenetic relationships among and between members of these genera and several previously undescribed species, we sequenced and analyzed the DNA-directed RNA polymerase II (rPB2), translation elongation factor 3-a (TEF3), b-tubulin (TUB2), 28S large subunit rDNA (LSU) and the internal transcribed spacer regions (ITS) in 68 strains, in addition to morphological and physiological investigations. To better understand the thermal dimorphism among these fungi, the dynamic process of transformation from mycelial to yeast-like or adiaspore-like forms was also assessed over a range of temperatures (6-42°C). Molecular data resolved the relationships and recognized five major well-supported lineages that correspond largely to the genus level. Emmonsia, typified by Emmonsia parva, is a synonym of Blastomyces that also accommodates Blastomyces helicus (formerly Emmonsia helica). Emmonsia crescens is phylogenetically distinct, and found closely related to a single strain from soil without known etiology. Blastomyces silverae, Emergomyces canadensis, Emergomyces europaeus and Emmonsia sola are newly described. Almost all of the taxa are associated with human and animal disease. Emmonsia crescens, B. dermatitidis and B. parvus are prevalently associated with pulmonary disease in humans or animals. Blastomyces helicus, B. percursus, Emergomyces africanus, Es. canadensis, Es. europaeus, Es. orientalis and Es. pasteurianus (formerly Emmonsia pasteuriana) are predominantly found in human hosts with immune disorders; no animal hosts are known for these species except B. helicus.

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Magnesium (Mg) and its alloys have been suggested as revolutionary biodegradable materials. However, fast degradation hinders its clinic application. To improve the corrosion resistance and biocompatibility of Mg-Nd-Zn-Zr alloy (JDBM), magnesium-aluminum-layered double hydroxide (Mg-Al LDH) was successfully introduced into Mg(OH) coating by hydrothermal treatment. The anions in the interlayer of Mg-Al LDH can be replaced by chloride ions, resulting in a relatively low chloride ion concentration near the surface of the coating. The favorable corrosion resistance of the coating was proved by polarization curves and hydrogen collection test. The Mg-Al LDH significantly promoted cell adhesion, migration and proliferation in vitro. In addition, the coating almost fulfilled the request of the clinical application in the hemolysis ratio test. Finally, in vivo results indicated that the coating offered the greatest long-lasting protection from corrosion and triggered the mildest inflammation comparing to the pure Mg(OH) coatings and untreated magnesium alloy. Mg(OH) coating containing Mg-Al LDH in the present study shows a promising application in improving anticorrosion and biocompatibility of Mg alloys, and might act as a platform for a further modification of Mg alloys ascribed to its special layer structure.