Life Cycle Of Filamentous Fungi Research Articles

Dynamics of Biomembrane Composition During the Life Cycle of Filamentous Fungi

Dynamics of Biomembrane Composition During the Life Cycle of Filamentous Fungi

Dysbiotic microbiota in autistic children and their mothers: persistence of fungal and bacterial wall-deficient L-form variants in blood

Based on our hypothesis for existing microbiota of wall-deficient variants (L-forms) in human blood, we created an innovative methodology, which allowed for the development of L-form populations from blood of all investigated people. In contrast to healthy controls, blood L-forms from autistic children and their mothers converted under appropriate conditions of cultivation into detectable opportunistic bacteria and fungi, а process demonstrated by light and transmission electron microscopy. It can be distinguished into two types of states – “eubiotic” blood microbiota in healthy individuals, and “dysbiotic” in autistic children and their mothers. Remarkably, the unifying finding for autistic children and their mothers was the presence in blood of wall-free variants from life-cycle of filamentous fungi. Increased specific IgG, IgM and IgA, together with typical mold growth were a decisive argument for proven presence of Aspergillus fumigatus in almost all of the autistic children. As it was demonstrated in our previous study, filterable L-forms can be transmitted by vertical pathway from mother to child before birth. Thus, it can be suggested that autistic children may be born already colonized with fungi, while a “silent aspergillosis” could contribute or even be a leading cause for neurodevelopmental disorders in the early childhood.

New insights from an old mutant: SPADIX4 governs fruiting body development but not hyphal fusion in Sordaria macrospora.

During the sexual life cycle of filamentous fungi, multicellular fruiting bodies are generated for the dispersal of spores. The filamentous ascomycete Sordaria macrospora has a long history as a model system for studying fruiting body formation, and two collections of sterile mutants have been generated. However, for most of these mutants, the underlying genetic defect remains unknown. Here, we investigated the mutant spadix (spd) that was generated by X-ray mutagenesis in the 1950s and terminates sexual development after the formation of pre-fruiting bodies (protoperithecia). We sequenced the spd genome and found a 22kb deletion affecting four genes, which we termed spd1-4. Generation of deletion strains revealed that only spd4 is required for fruiting body formation. Although sterility in S. macrospora is often coupled with a vegetative hyphal fusion defect, Δspd4 was still capable of fusion. This feature distinguishes SPD4 from many other regulators of sexual development. Remarkably, GFP-tagged SPD4 accumulated in the nuclei of vegetative hyphae and fruiting body initials, the ascogonial coils, but not in sterile tissue from the developing protoperithecium. Our results point to SPD4 as a specific determinant of fruiting body formation. Research on SPD4 will, therefore, contribute to understanding cellular reprogramming during initiation of sexual development in fungi.

Microcyle Conidiation in Filamentous Fungi

The typical life cycle of filamentous fungi commonly involves asexual sporulation after vegetative growth in response to environmental factors. The production of asexual spores is critical in the life cycle of most filamentous fungi. Normally, conidia are produced from vegetative hyphae (termed mycelia). However, fungal species subjected to stress conditions exhibit an extremely simplified asexual life cycle, in which the conidia that germinate directly generate further conidia, without forming mycelia. This phenomenon has been termed as microcycle conidiation, and to date has been reported in more than 100 fungal species. In this review, first, we present the morphological properties of fungi during microcycle conidiation, and divide microcycle conidiation into four simple categories, even though fungal species exhibit a wide variety of morphological differences during microcycle conidiogenesis. Second, we describe the factors that influence microcycle conidiation in various fungal species, and present recent genetic studies that have identified the genes responsible for this process. Finally, we discuss the biological meaning and application of microcycle conidiation.

Creating Surface Properties Using a Palette of Hydrophobins.

Small secreted proteins called hydrophobins play diverse roles in the life cycle of filamentous fungi. For example, the hydrophobin SC3 of Schizophyllum commune is involved in aerial hyphae formation, cell-wall assembly and attachment to hydrophobic surfaces. Hydrophobins are capable of self-assembly at a hydrophilic-hydrophobic interface, resulting in the formation of an amphipathic film. This amphipathic film can make hydrophobic surfaces of a liquid or a solid material wettable, while a hydrophilic surface can be turned into a hydrophobic one. These properties, among others, make hydrophobins of interest for medical and technical applications. For instance, hydrophobins can be used to purify proteins from complex mixtures; to reduce the friction of materials; to increase the biocompatibility of medical implants; to increase the solubility of water insoluble drugs; and to immobilize enzymes, for example, biosensor surfaces.

Dissecting Colony Development ofNeurospora crassaUsing mRNA Profiling and Comparative Genomics Approaches

Colony development, which includes hyphal extension, branching, anastomosis, and asexual sporulation, is a fundamental aspect of the life cycle of filamentous fungi; genetic mechanisms underlying these phenomena are poorly understood. We conducted transcriptional profiling during colony development of the model filamentous fungus Neurospora crassa, using 70-mer oligonucleotide microarrays. Relative mRNA expression levels were determined for six sections of defined age excised from a 27-h-old N. crassa colony. Functional category analysis showed that the expression of genes involved in cell membrane biosynthesis, polar growth, and cellular signaling was enriched at the periphery of the colony. The relative expression of genes involved in protein synthesis and energy production was enriched in the middle section of the colony, while sections of the colony undergoing asexual development (conidiogenesis) were enriched in expression of genes involved in protein/peptide degradation and unclassified proteins. A cross-examination of the N. crassa data set with a published data set of Aspergillus niger revealed shared patterns in the spatiotemporal regulation of gene orthologs during colony development. At present, less than 50% of genes in N. crassa have functional annotation, which imposes the chief limitation on data analysis. Using an evolutionary approach, we observed that the expression of phylogenetically conserved groups of genes was enriched in the middle section of an N. crassa colony whereas expression of genes unique to euascomycete species and of N. crassa orphan genes was enriched at the colony periphery and in the older, conidiating sections of a fungal colony.

Laboratory evaluation of gaseous essential oils (Part 1)

The antimicrobial activity of essential oils in the gaseous state was evaluated in a closed system using an airtight box. The gaseous activity was expressed by a minimum inhibitory dose (MID) per unit space that allowed no microbial growth after incubation. The MID values of seven oils determined against bacteria and fungi revealed that most oils were more active against filamentous fungi than against bacteria or yeasts. Gaseous essential oils inhibited three stages of the life cycle of filamentous fungi: germination of a conidium, elongation of vegetative mycelium, and sporulation of reproductive mycelium. Perilla and thyme oils exhibited therapeutic efficacy against experimental tinea pedis in guinea pigs and gaseous citron oil extended the survival time of mice exposed to fatal candidiasis.