26 research outputs found
Genetic signatures of variation in population size in a native fungal pathogen after the recent intensive plantation of its host tree
Historical fluctuations in forests’ distribution driven by past climate changes and anthropogenic activities can have large impacts on the demographic history of pathogens that have a long co-evolution history with these host trees. Using a population genetic approach, we investigated that hypothesis by reconstructing the demographic history of Armillaria ostoyae, one of the major pathogens of the maritime pine (Pinus pinaster), in the largest monospecific pine planted forest in Europe (south-western France). Genetic structure analyses and approximate Bayesian computation approaches revealed that a single pathogen population underwent a severe reduction in effective size (12 times lower) 1080–2080 generations ago, followed by an expansion (4 times higher) during the last 4 generations. These results are consistent with the history of the maritime pine forest in the region characterized by a strong recession during the last glaciation (~19 000 years ago) and massive plantations during the second half of the nineteenth century. Results suggest that recent and intensive plantations of a host tree population have offered the opportunity for a rapid spread and adaptation of their pathogens
Convergent coevolution in the domestication of coral mushrooms by fungus-growing ants.
Comparisons of phylogenetic patterns between coevolving symbionts can reveal rich details about the evolutionary history of symbioses. The ancient symbiosis between fungus-growing ants, their fungal cultivars, antibiotic-producing bacteria and cultivar-infecting parasites is dominated by a pattern of parallel coevolution, where the symbionts of each functional group are members of monophyletic groups. However, there is one outstanding exception in the fungus-growing ant system, the unidentified cultivar grown only by ants in the Apterostigma pilosum group. We classify this cultivar in the coral-mushroom family Pterulaceae using phylogenetic reconstructions based on broad taxon sampling, including the first mushroom collected from the garden of an ant species in the A. pilosum group. The domestication of the pterulaceous cultivar is independent from the domestication of the gilled mushrooms cultivated by all other fungus-growing ants. Yet it has the same overall assemblage of coevolved ant-cultivar-parasite-bacterium interactions as the other ant-grown fungal cultivars. This indicates a pattern of convergent coevolution in the fungus-growing ant system, where symbionts with both similar and very different evolutionary histories converge to functionally identical interactions
Genetic interaction networks mediate individual statin drug response in Saccharomyces cerevisiae
Eukaryotic genetic interaction networks (GINs) are extensively described in the Saccharomyces cerevisiae S288C model using deletion libraries, yet being limited to this one genetic background, not informative to individual drug response. Here we created deletion libraries in three additional genetic backgrounds. Statin response was probed with five queries against four genetic backgrounds. The 20 resultant GINs representing drug-gene and gene-gene interactions were not conserved by functional enrichment, hierarchical clustering, and topology-based community partitioning. An unfolded protein response (UPR) community exhibited genetic background variation including different betweenness genes that were network bottlenecks, and we experimentally validated this UPR community via measurements of the UPR that were differentially activated and regulated in statin-resistant strains relative to the statin-sensitive S288C background. These network analyses by topology and function provide insight into the complexity of drug response influenced by genetic background.status: publishe
Identification and Bioactivity of 3-<i>epi</i>-Xestoaminol C Isolated from the New Zealand Brown Alga <i>Xiphophora chondrophylla</i>
We report here the bioassay-guided
isolation of a new 1-deoxysphingoid,
3-<i>epi</i>-xestoaminol C (<b>1</b>), isolated from
the New Zealand brown alga <i>Xiphophora chondrophylla</i>. This is the first report of a 1-deoxysphingoid from a brown alga.
We describe the isolation and full structure elucidation of this compound,
including its absolute configuration, along with its bioactivity against
mycobacteria and mammalian cell lines and preliminary mechanism of
action studies using yeast chemical genomics
Bioactivity-Guided Metabolite Profiling of Feijoa (<i>Acca sellowiana</i>) Cultivars Identifies 4‑Cyclopentene-1,3-dione as a Potent Antifungal Inhibitor of Chitin Synthesis
Pathogenic fungi continue to develop
resistance against current
antifungal drugs. To explore the potential of agricultural waste products
as a source of novel antifungal compounds, we obtained an unbiased
GC-MS profile of 151 compounds from 16 commercial and experimental
cultivars of feijoa peels. Multivariate analysis correlated 93% of
the compound profiles with antifungal bioactivities. Of the 18 compounds
that significantly correlated with antifungal activity, 5 had not
previously been described from feijoa. Two novel cultivars were the
most bioactive, and the compound 4-cyclopentene-1,3-dione, detected
in these cultivars, was potently antifungal (IC<sub>50</sub> = 1–2
ÎĽM) against human-pathogenic <i>Candida</i> species.
Haploinsufficiency and fluorescence microscopy analyses determined
that the synthesis of chitin, a fungal-cell-wall polysaccharide, was
the target of 4-cyclopentene-1,3-dione. This fungal-specific mechanism
was consistent with a 22–70-fold reduction in antibacterial
activity. Overall, we identified the agricultural waste product of
specific cultivars of feijoa peels as a source of potential high-value
antifungal compounds
Polyhalogenated Indoles from the Red Alga <i>Rhodophyllis membranacea</i>: The First Isolation of Bromo-Chloro-Iodo Secondary Metabolites
An unusual tetrahalogenated indole
with the exceptionally rare inclusion of the three halogens bromine,
chlorine, and iodine was found using mass spectrometry within a fraction
of a semipurified extract obtained from the red alga <i>Rhodophyllis
membranacea.</i> We report herein the isolation and structure
elucidation, using a combination of NMR spectroscopy and mass spectrometry,
of 11 new tetrahalogenated indoles (<b>1</b>–<b>11</b>), including four bromochloroiodoindoles (<b>5</b>–<b>7</b>, <b>10</b>). Several were evaluated for cytotoxic
and antifungal activities against the HL-60 promyelocytic cell line
and <i>Saccharomyces cerevisiae</i>, respectively