Molecular identification of fungi microfossils in a Neoproterozoic shale rock.

Precambrian fossils of fungi are sparse, and the knowledge of their early evolution and the role they played in the colonization of land surface are limited. Here, we report the discovery of fungi fossils in a 810 to 715 million year old dolomitic shale from the Mbuji-Mayi Supergroup, Democratic Republic of Congo. Syngenetically preserved in a transitional, subaerially exposed paleoenvironment, these carbonaceous filaments of ~5 µm in width exhibit low-frequency septation (pseudosepta) and high-angle branching that can form dense interconnected mycelium-like structures. Using an array of microscopic (SEM, TEM, and confocal laser scanning fluorescence microscopy) and spectroscopic techniques (Raman, FTIR, and XANES), we demonstrated the presence of vestigial chitin in these fossil filaments and document the eukaryotic nature of their precursor. Based on those combined evidences, these fossil filaments and mycelium-like structures are identified as remnants of fungal networks and represent the oldest, molecularly identified remains of Fungi.

[Psychoeducation for overweight patients with psychiatric disorders: The Wellness program developed in Quebec]. / L'éducation thérapeutique du patient pour les clientèles psychiatriques présentant un surpoids : l'exemple du programme « Wellness ¼ développé au Québec.

OBJECTIVES: Patients with severe psychiatric disorders such as psychosis, bipolar disorder, and depression have a greater risk of suffering from being overweight or from obesity than the general population. This can in part be explained by medication-induced weight gain related to the use of antipsychotics, antidepressants and mood stabilizers. Fortunately, non-pharmacological interventions targeting modifications in lifestyle behaviors exist to help patients deal with weight gain and weight management. The main objective of this study is to assess the effectiveness of one of these interventions developed in Quebec (Canada), the Wellness Program. MATERIALS AND METHODS: The 12-week program, consisting of two to three weekly individual and group sessions, was administered to patients diagnosed with a severe psychiatric disorder (i.e. Psychotic Disorders, Bipolar Disorders, Major Depressive Disorder) and referred to a general hospital for significant weight problems. Topics of program sessions included: physical conditioning, nutrition, meal cooking, psychoeducation, motivation, relaxation training, and optional walking sessions. A total of 47 participants took part in this study and either initially received the intervention (n=31) or were placed in a waitlist control group and later received the intervention (n=16). The effectiveness of the program was measured using objective anthropometric (weight, Body Mass Index, waist circumference) and clinical (psychiatric symptoms, medication adherence, quality of life) variables from both experimental and control groups. Assessments were conducted at the end of the 12-week intervention and at a 3-month follow-up. RESULTS: After three months of active intervention, there were no significant differences between the two groups for most of the variables studied. Patients in the experimental group did show greater improvements in weight loss, Body Mass Index and waist circumference compared to the control group, but these positive changes were not statistically significant given the small sample size of the study. However, the results obtained at follow-up three months after the end of the program showed a significant impact of the program, albeit small, on weight, Body Mass Index, waist circumference and on some aspects of quality of life in the experimental group. CONCLUSION: Non-pharmacological interventions targeting healthy lifestyle behaviors and weight management, such as the Wellness Program, seem effective in improving anthropometric variables and quality of life in patients with severe psychiatric disorders such as psychosis and mood disorders. Given the potential clinical benefits, implementation in clinical settings and widespread dissemination is recommended. Indeed, these programs have the potential to limit weight gain associated with medications used to treat psychiatric disorders and to improve quality of life for these patients.

Oxalate secretion by ectomycorrhizal Paxillus involutus is mineral-specific and controls calcium weathering from minerals.

Trees and their associated rhizosphere organisms play a major role in mineral weathering driving calcium fluxes from the continents to the oceans that ultimately control long-term atmospheric CO2 and climate through the geochemical carbon cycle. Photosynthate allocation to tree roots and their mycorrhizal fungi is hypothesized to fuel the active secretion of protons and organic chelators that enhance calcium dissolution at fungal-mineral interfaces. This was tested using (14)CO2 supplied to shoots of Pinus sylvestris ectomycorrhizal with the widespread fungus Paxillus involutus in monoxenic microcosms, revealing preferential allocation by the fungus of plant photoassimilate to weather grains of limestone and silicates each with a combined calcium and magnesium content of over 10 wt.%. Hyphae had acidic surfaces and linear accumulation of weathered calcium with secreted oxalate, increasing significantly in sequence: quartz, granite < basalt, olivine, limestone < gabbro. These findings confirmed the role of mineral-specific oxalate exudation in ectomycorrhizal weathering to dissolve calcium bearing minerals, thus contributing to the geochemical carbon cycle.

Plant-driven weathering of apatite--the role of an ectomycorrhizal fungus.

Ectomycorrhizal (EcM) fungi are increasingly recognized as important agents of mineral weathering and soil development, with far-reaching impacts on biogeochemical cycles. Because EcM fungi live in a symbiotic relationship with trees and in close contact with bacteria and archaea, it is difficult to distinguish between the weathering effects of the fungus, host tree and other micro-organisms. Here, we quantified mineral weathering by the fungus Paxillus involutus, growing in symbiosis with Pinus sylvestris under sterile conditions. The mycorrhizal trees were grown in specially designed sterile microcosms in which the supply of soluble phosphorus (P) in the bulk media was varied and grains of the calcium phosphate mineral apatite mixed with quartz, or quartz alone, were provided in plastic wells that were only accessed by their fungal partner. Under P limitation, pulse labelling of plants with (14)CO(2) revealed plant-to-fungus allocation of photosynthates, with 17 times more (14)C transferred into the apatite wells compared with wells with only quartz. Fungal colonization increased the release of P from apatite by almost a factor of three, from 7.5 (±1.1) × 10(-10) mol m(-2) s(-1) to 2.2 (±0.52) × 10(-9) mol m(-2) s(-1). On increasing the P supply in the microcosms from no added P, through apatite alone, to both apatite and orthophosphate, the proportion of biomass in roots progressively increased at the expense of the fungus. These three observations, (i) proportionately more plant energy investment in the fungal partner under P limitation, (ii) preferential fungal transport of photosynthate-derived carbon towards patches of apatite grains and (iii) fungal enhancement of weathering rate, reveal the tightly coupled plant-fungal interactions underpinning enhanced EcM weathering of apatite and its utilization as P source.