A carnivorous mushroom paralyzes and kills nematodes via a volatile ketone.

The carnivorous mushroom Pleurotus ostreatus uses an unknown toxin to rapidly paralyze and kill nematode prey upon contact. We report that small lollipop-shaped structures (toxocysts) on fungal hyphae are nematicidal and that a volatile ketone, 3-octanone, is detected in these fragile toxocysts. Treatment of Caenorhabditis elegans with 3-octanone recapitulates the rapid paralysis, calcium influx, and neuronal cell death arising from fungal contact. Moreover, 3-octanone disrupts cell membrane integrity, resulting in extracellular calcium influx into cytosol and mitochondria, propagating cell death throughout the entire organism. Last, we demonstrate that structurally related compounds are also biotoxic to C. elegans, with the length of the ketone carbon chain being crucial. Our work reveals that the oyster mushroom has evolved a specialized structure containing a volatile ketone to disrupt the cell membrane integrity of its prey, leading to rapid cell and organismal death in nematodes.

Genomic analyses of two Italian oyster mushroom Pleurotus pulmonarius strains.

Pleurotus mushrooms are among the most cultivated fungi in the world and are highly valuable for food, medicine, and biotechnology industries. Furthermore, Pleurotus species are carnivorous fungi; they can rapidly paralyze and kill nematodes when nutrient-deprived. The predator-prey interactions between Pleurotus and nematodes are still widely unexplored. Moreover, the molecular mechanisms and the genes involved in the carnivorous behavior of Pleurotus mushrooms remain a mystery. We are attempting to understand the interactions between Pleurotus mushrooms and their nematode prey through genetic and genomic analyses. Two single spores (ss2 and ss5) isolated from a fruiting body of Pleurotus pulmonarius exhibited significant differences in growth and toxicity against nematodes. Thus, using PacBio long reads, we assembled and annotated two high-quality genomes for these two isolates of P. pulmonarius. Each of these assemblies contains 23 scaffolds, including 6 (ss2) and 8 (ss5) telomere-to-telomere scaffolds, and they are among the most complete assembled genomes of the Pleurotus species. Comparative analyses identified the genomic differences between the two P. pulmonarius strains. In sum, this work provides a genomic resource that will be invaluable for better understanding the Italian oyster mushroom P. pulmonarius.

Genome sequence of the oyster mushroom Pleurotus ostreatus strain PC9.

The oyster mushroom Pleurotus ostreatus is a basidiomycete commonly found in the rotten wood and it is one of the most cultivated edible mushrooms globally. Pleurotus ostreatus is also a carnivorous fungus, which can paralyze and kill nematodes within minutes. However, the molecular mechanisms of the predator-prey interactions between P. ostreatus and nematodes remain unclear. PC9 and PC15 are two model strains of P. ostreatus and the genomes of both strains have been sequenced and deposited at the Joint Genome Institute (JGI). These two monokaryotic strains exhibit dramatic differences in growth, but because PC9 grows more robustly in laboratory conditions, it has become the strain of choice for many studies. Despite the fact that PC9 is the common strain for investigation, its genome is fragmentary and incomplete relative to that of PC15. To overcome this problem, we used PacBio long reads and Illumina sequencing to assemble and polish a more integrated genome for PC9. Our PC9 genome assembly, distributed across 17 scaffolds, is highly contiguous and includes five telomere-to-telomere scaffolds, dramatically improving the genome quality. We believe that our PC9 genome resource will be useful to the fungal research community investigating various aspects of P. ostreatus biology.

Forward genetic screens identified mutants with defects in trap morphogenesis in the nematode-trapping fungus Arthrobotrys oligospora.

Nematode-trapping fungi (NTF) are carnivorous fungi that prey on nematodes under nutrient-poor conditions via specialized hyphae that function as traps. The molecular mechanisms involved in the interactions between NTF and their nematode prey are largely unknown. In this study, we conducted forward genetic screens to identify potential genes and pathways that are involved in trap morphogenesis and predation in the NTF Arthrobotrys oligospora. Using Ethyl methanesulfonate and UV as the mutagens, we generated 5552 randomly mutagenized A. oligospora strains and identified 15 mutants with strong defects in trap morphogenesis. Whole-genome sequencing and bioinformatic analyses revealed mutations in genes with roles in signaling, transcription or membrane transport that may contribute to the defects of trap morphogenesis in these mutants. We further conducted functional analyses on a candidate gene, YBP-1, and demonstrate that mutation of that gene was causative of the phenotypes observed in one of the mutants. The methods established in this study might provide helpful insights for establishing forward genetic screening methods for other non-model fungal species.

Prescribing patterns and healthcare costs of gout.

OBJECTIVE/METHODS: The Longitudinal Health Insurance Database (LHID) 2010 was used to identify gout cases and their number of gout flares. RESULTS: Out of 21,376 gout patients, a total of 3561 (16.7%) had frequent gout flares (≥3 gout flares/year). Average all-cause healthcare utilization (35.9 visits vs. 30.7 visits; p < .001) and gout-related utilization (22.7 visits vs. 15.6 visits; p < .001) were higher in frequent gout flare patients than in those with infrequent gout flares. The median gout-related cost (USD $369 vs. $285; p < .001), but not all-cause costs (p = .25), were higher in frequent gout flare patients compared to the infrequent group. Over 55.8% of the flares were treated with colchicine + NSAIDs. CONCLUSIONS: In conclusion, patients with frequent gout flares had higher healthcare utilization and gout-related healthcare costs. Colchicine + NSAIDs are commonly used therapy for gout flare.

Evaluation of healthcare costs and utilization for patients with gout: a population-based matched cohort study.

OBJECTIVES: To better understand the economic burden of gout patients in Taiwan, a nationwide retrospective study was conducted to compare the healthcare costs and utilization between gout and gout-free patients. METHODS: The Longitudinal Health Insurance Database (LHID) 2010 was used to identify gout cases and matched gout-free controls. Gout cases were defined as having (1) at least three instances of diagnoses of gout on medical claims, or (2) one diagnosis of gout with at least one gout-related pharmacy claim in 2011. A control cohort was matched with cases at a 3:1 ratio by age, gender, residential area, and the Charlson Comorbidity Index. All medical utilization and costs per patient within the 365 days following the index date were compared between cases and controls. RESULTS: Out of 993,332 beneficiaries, a total of 21,376 matched gout patients met the gout inclusion criteria. Compared to controls, gout patients had more outpatient visits (mean = 31.2 vs 22.6), inpatient visits (mean = 1.7 vs 1.5), and ER visits (mean = 1.9 vs 1.7) (all p < .0001), as well as more outpatient costs (median = USD $634 vs $404), inpatient costs (median = USD $1330 vs $1254), and ER costs (median = USD $87 vs $89) (all p < .05). CONCLUSION: Gout patients had higher medical utilization and costs than gout-free patients. In gout patients, all-cause and gout-related utilization were mostly outpatient visits, whereas most of the all-cause and gout-related costs were due to hospitalization. The study findings could be useful for future economic evaluations and healthcare resource allocation.