An MRI time course of 512 echo-planar images (EPI) in resting human brain obtained every 250 ms reveals fluctuations in signal intensity in each pixel that have a physiologic origin. Regions of the sensorimotor cortex that were activated secondary to hand movement were identified using functional MRI methodology (FMRI). Time courses of low frequency (< 0.1 Hz) fluctuations in resting brain were observed to have a high degree of temporal correlation (P < 10(-3)) within these regions and also with time courses in several other regions that can be associated with motor function. It is concluded that correlation of low frequency fluctuations, which may arise from fluctuations in blood oxygenation or flow, is a manifestation of functional connectivity of the brain.

Functional connectivity in the motor cortex of resting human brain using echo-planar MRI.

Ainsworth and Bisby's Dictionary of the Fungi

The fungus Aspergillus fumigatus is an opportunistic human pathogen in immunocompromised individuals and is associated with severe asthma and sinusitis. Despite accumulating evidence that recombination and gene flow occur in Aspergillus, until now only asexual reproduction has been observed in the species. Now, 145 years after it was first characterized, Aspergillus is shown to reproduce sexually. Isolates of two complementary mating types are reported. Implications of this demonstration include a possibility of classical genetic analyses that in turn will facilitate research into the genetic basis of pathogenicity and fungicide resistance. Aspergillus fumigatus is an opportunistic human pathogen in immunocompromised individuals and is associated with severe asthma and sinusitis, and has only been known to reproduce asexually. This paper now shows that it can reproduce sexually, for which isolates of complementary mating type are required. Aspergillus fumigatus is a saprotrophic fungus whose spores are ubiquitous in the atmosphere1. It is also an opportunistic human pathogen in immunocompromised individuals, causing potentially lethal invasive infections2,3, and is associated with severe asthma and sinusitis4. The species is only known to reproduce by asexual means5, but there has been accumulating evidence for recombination and gene flow from population genetic studies5,6,7,8, genome analysis9,10, the presence of mating-type genes8,10 and expression of sex-related genes8 in the fungus. Here we show that A. fumigatus possesses a fully functional sexual reproductive cycle that leads to the production of cleistothecia and ascospores, and the teleomorph Neosartorya fumigata is described. The species has a heterothallic breeding system; isolates of complementary mating types are required for sex to occur. We demonstrate increased genotypic variation resulting from recombination between mating type and DNA fingerprint markers in ascospore progeny from an Irish environmental subpopulation. The ability of A. fumigatus to engage in sexual reproduction is highly significant in understanding the biology and evolution of the species. The presence of a sexual cycle provides an invaluable tool for classical genetic analyses and will facilitate research into the genetic basis of pathogenicity and fungicide resistance in A. fumigatus, with the aim of improving methods for the control of aspergillosis. These results also yield insights into the potential for sexual reproduction in other supposedly ‘asexual’ fungi.

Discovery of a sexual cycle in the opportunistic fungal pathogen Aspergillus fumigatus

Filamentous fungi produce a number of small bioactive molecules as part of their secondary metabolism ranging from benign antibiotics such as penicillin to threatening mycotoxins such as aflatoxin. Secondary metabolism can be linked to fungal developmental programs in response to various abiotic or biotic external triggers. The velvet family of regulatory proteins plays a key role in coordinating secondary metabolism and differentiation processes such as asexual or sexual sporulation and sclerotia or fruiting body formation. The velvet family shares a protein domain that is present in most parts of the fungal kingdom from chytrids to basidiomycetes. Most of the current knowledge derives from the model Aspergillus nidulans where VeA, the founding member of the protein family, was discovered almost half a century ago. Different members of the velvet protein family interact with each other and the nonvelvet protein LaeA, primarily in the nucleus. LaeA is a methyltransferase-domain protein that functions as a regulator of secondary metabolism and development. A comprehensive picture of the molecular interplay between the velvet domain protein family, LaeA and other nuclear regulatory proteins in response to various signal transduction pathway starts to emerge from a jigsaw puzzle of several recent studies.

Coordination of secondary metabolism and development in fungi: the velvet family of regulatory proteins.

Background: The fungal genus Aspergillus is of critical importance to humankind. Species include those with industrial applications, important pathogens of humans, animals and crops, a source of potent carcinogenic contaminants of food, and an important genetic model. The genome sequences of eight aspergilli have already been explored to investigate aspects of fungal biology, raising questions about evolution and specialization within this genus. Results: We have generated genome sequences for ten novel, highly diverse Aspergillus species and compared these in detail to sister and more distant genera. Comparative studies of key aspects of fungal biology, including primary and secondary metabolism, stress response, biomass degradation, and signal transduction, revealed both conservation and diversity among the species. Observed genomic differences were validated with experimental studies. This revealed several highlights, such as the potential for sex in asexual species, organic acid production genes being a key feature of black aspergilli, alternative approaches for degrading plant biomass, and indications for the genetic basis of stress response. A genome-wide phylogenetic analysis demonstrated in detail the relationship of the newly genome sequenced species with other aspergilli. Conclusions: Many aspects of biological differences between fungal species cannot be explained by current knowledge obtained from genome sequences. The comparative genomics and experimental study, presented here, allows for the first time a genus-wide view of the biological diversity of the aspergilli and in many, but not all, cases linked genome differences to phenotype. Insights gained could be exploited for biotechnological and medical applications of fungi.

/pdf/comparative-genomics-reveals-high-biological-diversity-and-3dajjpv52r.pdf

Comparative genomics reveals high biological diversity and specific adaptations in the industrially and medically important fungal genus Aspergillus

Mating Type and the Genetic Basis of Self-Fertility in the Model Fungus Aspergillus nidulans

Usnea species of the Neuropogon group are amongst the most widespread and abundant macrolichens in Antarctic regions. Four principal species, U. antarctica, U. aurantiaco-atra, U. sphacelata and U. subantarctica, have been described on morphological grounds. However, identification to species level is often difficult and atypical morphologies frequently arise. Over 400 specimens were collected on the Antarctic Peninsula and Falkland Islands. Both morphological and molecular characters (ITS and RPB1) were used to compare samples to clarify taxonomic relationships. Morphological characteristics used included presence of apothecia, apothecial rays, soredia, papillae, fibrils, pigmentation and the diameter of the central axis as a proportion of branch diameter. Results revealed a very close relationship between U. antarctica and U. aurantiaco-atra, suggesting that they might constitute a species pair or be conspecific. Usnea sphacelata was comprised of at least two genetically distinct groups with no clear differences in morphology. One group included the first reported fertile specimen of this species. Usnea subantarctica was phylogenetically distinct from the other main Antarctic Usnea species, but clustered with U. trachycarpa. Genetic variation was evident within all species although there was no clear correlation between geographic origin and genetic relatedness. Phylogenetic analyses indicated that species circumscription in the Neuropogon group needs revision, with the principal species being non-monophyletic. None of the morphological characters, or groups of characters, used in this study proved to be completely unambiguous markers for a single species. However, axis thickness was supported as being informative for the identification of monophyletic lineages within the group.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102007000107

Phylogenetic and morphological analysis of Antarctic lichen-forming Usnea species in the group Neuropogon

Sex in the extremes: lichen-forming fungi

Breeding systems in the lichen-forming fungal genus Cladonia.

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Papers

Mating Type and the Genetic Basis of Self-Fertility in the Model Fungus Aspergillus nidulans

Phylogenetic and morphological analysis of Antarctic lichen-forming Usnea species in the group Neuropogon

Sex in the extremes: lichen-forming fungi

Breeding systems in the lichen-forming fungal genus Cladonia.