Higher-level phylogenetic relationships of Homobasidiomycetes (mushroom-forming fungi) inferred from four rDNA regions.

Homobasidiomycetes include approximately 13,000 described species of mushroom-forming fungi and related taxa. The higher-level classification of this ecologically important group has been unsettled for over 100 years. The goals of the present study were to evaluate a recent phylogenetic classification by Hibbett and Thorn that divided the homobasidiomycetes into eight major unranked clades, and to infer the higher-order relationships among these clades. A dataset of 93 species that represent all eight previously recognized clades was assembled, with 3800 bp of sequence data from nuclear and mitochondrial large and small subunit rDNAs for each taxon. Parsimony and maximum-likelihood analyses support the monophyly of the eight major clades recognized by Hibbett and Thorn. Most groups are strongly supported in bootstrapped parsimony analyses, but the polyporoid clade remains weakly supported. For the first time, the sister-group relationship of the euagarics clade and bolete clade is strongly supported, and the Hygrophoraceae is strongly supported as the sister group of the rest of the euagarics clade. Nevertheless, the backbone of the homobasidiomycete phylogeny, and the internal structure of several clades, remain poorly resolved.     

Study of response of Swiss Webster mice to light subunit of mushroom tyrosinase

The light subunit of mushroom, Agaricus bisporus, tyrosinase (LSMT), has been identified as an extrinsic component of the enzyme. Its function is unknown, but it can cross an epithelial cell layer, which suggests that it can be absorbed by the intestine. A similar capability has been demonstrated for the HA-33 component of the progenitor toxin from Clostridium botulinum, which is the closest structural homolog of LSMT. Unlike HA-33, LSMT appears to be non-immunogenic as shown by preliminary tests in Swiss Webster mice. We investigated the immunogenicity and histopathology of LSMT in mice to determine its safety in vivo. LSMT did not evoke generation of antibodies after prolonged periods of intraperitoneal administration. Histopathological observations confirmed the absence of responses in organs after twelve weekly administrations of LSMT. We found that LSMT is not toxic and is less immunogenic than the C. botulinum HA-33 protein, which supports further research and development for pharmaceutical application.     

Analysis of character correlations among wood decay mechanisms,mating systems,and substrate ranges in homobasidiomycetes

Homobasidiomycetes include the majority of wood-decaying fungi. Two basic forms of wood decay are known in homobasidiomycetes: white rot, in which lignin and cellulose are degraded, and brown rot, in which lignin is not appreciably degraded. An apparent correlation has been noted between production of a brown rot, decay of conifer substrates, and possession of a bipolar mating system (which has a single mating-type locus, in contrast to tetrapolar systems, which have two mating-type loci). The goals of this study were to infer the historical pattern of transformations in decay mode, mating type, and substrate range characters, and to determine if a causal relationship exists among them. Using nuclear and mitochondrial rDNA sequences, we performed a phylogenetic analysis of 130 species of homobasidiomycetes and performed ancestral state reconstructions by using parsimony on a range of trees, with various loss:gain cost ratios. We evaluated pairwise character correlations by using the concentrated changes test (CCT) of Maddison and the maximum likelihood (ML) method of Pagel. White rot, tetrapolar mating systems, and the ability to decay conifers and hardwoods appear to be plesiomorphic in homobasidiomycetes, whereas brown rot, bipolar mating systems, and exclusive decay of conifers appear to have evolved repeatedly. The only significant correlation among characters was that between brown rot (as the independent character) and exclusive decay of conifer substrates (P < 0.03). This correlation was supported by the CCT on a range of plausible trees, although not with every reconstruction of ancestral states, and by the ML test. Our findings suggest that the evolution of brown rot has promoted repeated shifts to specialization for confier substrates.     

Sprint interval training (SIT) is an effective method to maintain cardiorespiratory fitness (CRF) and glucose homeostasis in Scottish adolescents

The present study examined the physiological impact of a school based sprint interval training (SIT) intervention in replacement of standard physical education (SPE) class on cardio-respiratory fitness (CRF) and glucose homeostasis during the semester following summer vacation. Participants (n=49) were randomly allocated to either intervention (SIT; n=26, aged 16.9 ± 0.3 yrs) or control group who underwent standard physical education (SPE; n=23, aged 16.8 ± 0.6 yrs). CRF (VO₂max) and glucose homeostasis were obtained prior-to and following 7 weeks of SIT exercise. Significant group x time interaction was observed for CRF (P < 0.01) with non-significant trends for fasting insulin (P= 0.08), and HOMA-IR (P=0.06). CRF decreased (P < 0.01) in SPE such that POST intervention CRF was significantly lower (P< 0.05) in SPE. Fasting plasma glucose (P < 0.01), insulin (P< 0.01) and HOMA-IR (P< 0.01) increased significantly amongst SPE. The main finding of the present study is that 7-weeks of SIT exercise is an effective method of maintaining (but not improving) CRF and fasting insulin homeostasis amongst school-going adolescents. SIT exercise demonstrates potential as a time efficient physiological adjunct to standard PE class in order to maintain CRF during the school term.     

A model of blood flow in the mesenteric arterial system

Background  

There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure) mainly due to the highly unspecific nature of the disease.     

Molecular phylogenetics of the Gloeophyllales and relative ages of clades of Agaricomycotina producing a brown rot

The Gloeophyllales is a recently described order of Agaricomycotina containing a morphologically diverse array of polypores (Gloeophyllum), agarics (Neolentinus, Heliocybe) and resupinate fungi (Veluti-Veluticeps, Boreostereum, Chaetodermella), most of which have been demonstrated to produce a brown-rot mode of wood decay and are found preferentially on coniferous substrates. Multiple phylogenetic studies have included taxa of Gloeophyllales, but none have sampled the order thoroughly, and so far only ribosomal RNA genes have been used. Consequently the limits and higher level placement of the Gloeophyllales are obscure. We obtained sequence data for three protein-coding genes (rpb2, atp6, tef1) and three rRNA regions (nuc-ssu, nuc-lsu, 5.8S) in 19 species of Gloeophyllales representing seven genera and analyzed them together with a diverse set of Agaricomycotina, emphasizing Polyporales. Boreostereum, which is suspected to produce a white rot, is the sister group of the rest of the Gloeophyllales, all of which produce a brown rot. Gloeophyllum contains at least two independent clades, one of which might correspond to the genus Osmoporus. White rot and resupinate fruiting bodies appear to be plesiomorphic in Gloeophyllales. Relaxed molecular clock analyses suggest that the Gloeophyllales arose in the Cretaceous, after the origin of Pinaceae.     

Conservation of biotrophy in Hygrophoraceae inferred from combined stable isotope and phylogenetic analyses

The nutritional modes of genera in Hygrophoraceae (Basidiomycota: Agaricales), apart from the ectomycorrhizal Hygrophorus and lichen-forming taxa, are uncertain. New δ(15)N and δ(13)C values were obtained from 15 taxa under Hygrophoraceae collected in central Massachusetts and combined with isotopic datasets from five prior studies including a further 12 species using a data standardization method to allow cross-site comparison. Based on these data, we inferred the probable nutritional modes for species of Hygrophorus, Hygrocybe, Humidicutis, Cuphophyllus and Gliophorus. A phylogeny of Hygrophoraceae was constructed by maximum likelihood analysis of nuclear ribosomal 28S and 5.8S sequences and standardized δ(15)N and δ(13)C values were used for parsimony optimization on this phylogeny. Our results supported a mode of biotrophy in Hygrocybe, Humidicutis, Cuphophyllus and Gliophorus quantitatively unlike that in more than 450 other fungal taxa sampled in the present and prior studies. Parsimony optimization of stable isotope data suggests moderate conservation of nutritional strategies in Hygrophoraceae and a single switch to a predominantly ectomycorrhizal life strategy in the lineage leading to Hygrophorus. We conclude that Hygrophoraceae of previously unknown nutritional status are unlikely to be saprotrophs and are probably in symbiosis with bryophytes or other understory plants.     

Morphometric and phytochemical characterization of chaura fruits (Gaultheria pumila): a native Chilean berry with commercial potential

Background

For the first time, a morphometric characterization of chaura (Gaultheria pumila) fruits has been conducted between natural populations growing in the Villarrica National Park, Araucania Region, Chile. Chaura is a native Ericaceae from Chile that produces aromatic and tasty fruits which could be of agricultural interest.

Results

To influence the decision for a further domestication of G. pumila, both the fruit sizes (indicator of productivity) and the nutritional properties of the fruits have been determined from different subpopulations. Samples were a total of 74 plants and 15 fruits per plant which were randomly harvested following its natural distribution around the Villarrica volcano. Altogether, fresh weight, shape, color, diameter in the pole and the equatorial dimensions were determined as phenotypic traits of the G. pumila fruits. Meanwhile the total soluble solids, anthocyanin and pectin contents were calculated as nutritional traits of the Chaura fruits. Results showed a high phenotypic diversity between the sampled population with three main fruit shapes and three predominant colors. The round shapes were the most abundant, whereas a significant correlation was found among fruit size with weight and color. The highest fresh weight (597.3 mg), pole diameter (7.1 mm) and equatorial diameter (6.5 mm) were estimated in the pink color fruits.

Conclusions

The total amount of anthocyanin was higher in red fruits, while the maximum pectin content was obtained in the round white fruits. Overall results must pave the way for a further domestication and introduction of the Chaura species in the agro-productive system in Chile.