RESUMO
Members of the mitosporic fungal form-genus Stachybotrys, including common indoor contaminants Stachybotrys chartarum, Stachybotrys echinata and Stachybotrys chlorohalonata, are capable of producing potent, protein synthesis-inhibiting, trichothecene mycotoxins. A combined multi-gene approach was used to investigate relationships among species of Stachybotrys against which the presence/absence of the trichothecene biosynthetic pathway gene, trichodiene synthase (tri5), was evaluated. Phylogenetic analyses partitioned species of Stachybotrys into three strongly supported lineages, two of which contained common indoor taxa. No tri5 PCR product was amplified from members of the third clade, which included the only member of the group with a known sexual state, Stachybotrys albipes. Isolates grouped with S. albipes also tested negative for tri5 in Southern analyses. The phylogenetic distribution of tri5 was consistent with known toxin production for the group. For isolates with tri5 product, Bayesian analysis suggested that signal from amino acid determining sites conflicted with the combined phylogeny. Incongruence however, was not supported by either SH-test results or maximum likelihood analyses. Moreover, sites rates analysis showed that tri5 was highly conserved at the amino acid level suggesting that identity at variable sites, among otherwise divergent taxa, might be the result of chance events.
Assuntos
Carbono-Carbono Liases/genética , Proteínas Fúngicas/genética , Filogenia , Stachybotrys/classificação , Stachybotrys/enzimologia , Carbono-Carbono Liases/metabolismo , Microbiologia Ambiental , Proteínas Fúngicas/metabolismo , Dados de Sequência Molecular , Stachybotrys/genética , Stachybotrys/isolamento & purificação , Tricotecenos/biossínteseRESUMO
We reassessed the circumscription of the cantharelloid clade and identified monophyletic groups by using nLSU, nSSU, mtSSU and RPB2 sequence data. Results agreed with earlier studies that placed the genera Cantharellus, Craterellus, Hydnum, Clavulina, Membranomyces, Multiclavula, Sistotrema, Botryobasidium and the family Ceratobasidiaceae in that clade. Phylogenetic analyses support monophyly of all genera except Sistotrema, which was highly polyphyletic. Strongly supported monophyletic groups were: (i) Cantharellus-Craterellus, Hydnum, and the Sistotrema confluens group; (ii) Clavulina-Membranomyces and the S. brinkmannii-oblongisporum group, with Multiclavula being possibly sister of that clade; (iii) the Sistotrema eximum-octosporum group; (iv) Sistotrema adnatum and S. coronilla. Positions of Sistotrema raduloides and S. athelioides were unresolved, as were basal relationships. Botryobasidium was well supported as the sister taxon of all the above taxa, while Ceratobasidiaceae was the most basal lineage. The relationship between Tulasnella and members of the cantharelloid clade will require further scrutiny, although there is cumulative evidence that they are probably sister groups. The rates of molecular evolution of both the large and small nuclear ribosomal RNA genes (nuc-rDNA) are much higher in Cantharellus, Craterellus and Tulasnella than in the other cantharelloid taxa, and analyses of nuc-rDNA sequences strongly placed Tulasnella close to Cantharellus-Craterellus. In contrast analyses with RPB2 and mtSSU sequences placed Tulasnella at the base of the cantharelloid clade. Our attempt to reconstruct a "supertree" from tree topologies resulting from separate analyses that avoided phylogenetic reconstruction problems associated with missing data and/or unalignable sequences proved unsuccessful.
Assuntos
Basidiomycota/classificação , Biologia Computacional/métodos , DNA Fúngico/genética , DNA Mitocondrial/genética , DNA Ribossômico/genética , Filogenia , Basidiomycota/genética , Basidiomycota/fisiologia , Evolução Molecular , Dados de Sequência Molecular , RNA Polimerase II/genética , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Análise de Sequência de DNARESUMO
Decipinin A (1), a new compound with antifungal and antibacterial activity, has been isolated from liquid cultures of the coprophilous fungus Podospora decipiens (JS 270). Two new tetracyclic sesquiterpene lactones, decipienolides A (2) and B (3), were also obtained from this isolate as an inseparable mixture of epimers that showed antibacterial activity. The structures of 1-3 were elucidated by analysis of 1D and 2D NMR data, aided by chemical shift comparisons to related compounds.
