Fungal morphogenesis and host invasion

Many fungal pathogens undergo morphological transformations during host invasion. However, the significance of this for fungal pathogenesis is not clear. Both yeast and hyphal cells have properties well suited to tissue invasion and evasion of the immune system. However, molecular control circuits that regulate morphogenesis also regulate the expression of other virulence traits. To establish the extent to which morphogenesis impacts on pathogenesis, it is necessary to characterise the morphology of the fungus at different stages and locations during the natural history of a disease and to untangle how gene expression is modulated at these stages. This review considers the role of morphogenesis in fungal infection and argues that no simple, universal relationship can be drawn between morphology and the invasive potential of a fungus.     

Studies in sporotrichosis: Fungal morphogenesis and pathogenicity in differing environments

Sporothrix schenckii exhibits different morphology and pathogenic properties according to the source and circumstances of its growth. The present study considers the morphology and experimental pathogenicity in relation to — the wild strains; the possible circumstances enhancing pathogenicity in strains recovered from the soil; the rate and nature of the transformational steps in morphology, in human and experimental infections by established pathogenic strains; the elimination of pathogenic strains to the surface of clinical lesions, enabling a simplified diagnostic proof of infection; the rate and nature of the reversion of pathogenic forms to the wild type when the constraints of the host are lessened; the plasticity of conidiumpigmentation as a sign of pathogenicity; the morphological conversions on moist wattle-wood as occur in the Gold Mines; and a note on the therapeutic value of itraconazole.Host resistance is seen to play a larger part in morphology of the pathogenic phase, and exhaustion of natural food resources as the generator of potentially pathogenic forms.     

In hot pursuit: fluctuating mating system and sexual selection in sand lizards

A changing climate is expected to have profound effects on many aspects of ectotherm biology. We report on a decade-long study of free-ranging sand lizards (Lacerta agilis), exposed to an increasing mean mating season temperature and with known operational sex ratios. We assessed year-to-year variation in sexual selection on body size and postcopulatory sperm competition and cryptic female choice. Higher temperature was not linked to strength of sexual selection on body mass, but operational sex ratio (more males) did increase the strength of sexual selection on body size. Elevated temperature increased mating rate and number of sires per clutch with positive effects on offspring fitness. In years when the "quality" of a female's partners was more variable (in standard errors of a male sexual ornament), clutches showed less multiple paternity. This agrees with prior laboratory trials in which females exercised stronger cryptic female choice when male quality varied more. An increased number of sires contributing to within-clutch paternity decreased the risk of having malformed offspring. Ultimately, such variation may contribute to highly dynamic and shifting selection mosaics in the wild, with potential implications for the evolutionary ecology of mating systems and population responses to rapidly changing environmental conditions.     

Fungal morphogenesis induced by natural and synthetic substances: Herniarin-induced alterations in the dermatophyte Microsporum cookie Ajello

Abstract

The effects of either synthetic or natural substances on the normal morphogenetic processes in fungi are reviewed. Original results concerning the changes induced in the dermatophyte Microsporum cookei Ajello by the UVA-activated coumarin, herniarin, are reported. Alterations in the shape and wall assembly of parietal components are discussed on the basis of the most recent knowledge on the formation and growth of fungal hyphae.     

Signaling in morphogenesis: transport cues in morphogenesis

Extracellular transport processes play critical roles in morphogenesis. While diffusive transport effects on morphogenesis are well illustrated in examples like blood capillary architecture and in cell morphogenetic responses to the local extracellular protein environment, the effects of fluid convection, although important in many developing and regenerating tissues, are not well understood. Convective forces are present whenever a hydrated tissue undergoes dynamic mechanical strain, and so convection could not only dominate the transport of large molecules like proteins, but might also serve as a mechanism for mechanosensing. The complex interdependence of mechanical forces, protein transport and extracellular morphogen gradients needs to be elucidated in a comprehensive way in order for the importance of transport on morphogenesis to be fully appreciated.     

Fungal horizons: the Asilomar Fungal Genetics Conference 2007

This meeting report covers advances presented at the 2007 Asilomar Fungal Genetics Conference that expand our understanding of fungal biology and the myriad ways in which studies of organisms in this ubiquitous and successful kingdom of life advance an understanding of conserved biological principles.     

Fungal horizons: the Asilomar Fungal Genetics Conference 2007.

This meeting report covers advances presented at the 2007 Asilomar Fungal Genetics Conference that expand our understanding of fungal biology and the myriad ways in which studies of organisms in this ubiquitous and successful kingdom of life advance an understanding of conserved biological principles.     

Satoshi Omura: in pursuit of nature's bounty

Professor Satoshi Omura has spent over 40 years searching for bioactive compounds in naturally occurring microorganisms, discovering more than 330 biomedically and commercially significant compounds in the process. The discovery, development and delivery of the drug ivermectin has pioneered the way for subsequent partnerships between the public and private sectors, as well as international collaborations and drug donation programmes. It has involved a variety of ground-breaking steps, providing a curative drug that will help rid Africa and the world of at least one of the most devastating of all human diseases, onchocerciasis. It has also improved the health of pets and livestock around the globe, and encouraged development of a community-based delivery mechanism that could herald a revolution in public health care in Africa.     

Bioelectromagnetics in morphogenesis

Understanding the factors that allow biological systems to reliably self-assemble consistent, highly complex, four dimensional patterns on many scales is crucial for the biomedicine of cancer, regeneration, and birth defects. The role of chemical signaling factors in controlling embryonic morphogenesis has been a central focus in modern developmental biology. While the role of tensile forces is also beginning to be appreciated, another major aspect of physics remains largely neglected by molecular embryology: electromagnetic fields and radiations. The continued progress of molecular approaches to understanding biological form and function in the post genome era now requires the merging of genetics with functional understanding of biophysics and physiology in vivo. The literature contains much data hinting at an important role for bioelectromagnetic phenomena as a mediator of morphogenetic information in many contexts relevant to embryonic development. This review attempts to highlight briefly some of the most promising (and often underappreciated) findings that are of high relevance for understanding the biophysical factors mediating morphogenetic signals in biological systems. These data originate from contexts including embryonic development, neoplasm, and regeneration.     

Hyaluronan in morphogenesis

Hyaluronan is a very large polysaccharide that is found in extracellular matrices, at the cell surface and inside cells. This review focuses on the functions of hyaluronan directly associated with the cell surface, where it is commonly present as the essential core of a highly hydrated pericellular matrix that contains several other components (hyaladherins) bound to hyaluronan. Three major molecular characteristics of hyaluronan contribute to its physiological functions: its unique hydrodynamic properties, its interactions with structural extracellular hyaladherins, and its instructive effects on cell signaling and behavior. Recent studies of hyaluronan-deficient mouse embryos illustrate the importance of each of these classes of function of hyaluronan. It is postulated that the morphogenetic effects of hyaluronan are due to its ability to act as a template for assembly of a multi-component, pericellular matrix as well as to its physical properties. This matrix would provide a hydrated environment in which cells are separated from structural barriers to morphogenetic changes and receive signals from hyaluronan itself and from associated factors.     

Fungal Keratitis: Epidemiological Profile in Argentina

Purpose of Review

The purpose of this review is to describe the epidemiology and species distribution of fungi-causing keratitis in Argentina during the past 10 years.

Recent Findings

In Argentina, reports of distribution and frequency of fungal keratitis are scarce and little is known about its current epidemiology.In the present study, a review of the published data on fungal keratitis was done according to the global context focusing on the current situation in our country.

Summary

Data presented here were obtained in a reference ophthalmological hospital in the Autonomous city of Buenos Aires from 2007 to 2017 and represents an approach to the current status of fungal keratitis. However, larger national data is required to assess the actual epidemiological situation in Argentina.

     

Fungal Thyroiditis: An Overview

The authors review the epidemiology, clinical manifestations, diagnosis, and treatment of fungal thyroiditis cases previously reported in the medical literature. Aspergillus was by far the most common cause of fungal thyroiditis. Immunocompromised patients, such as those with leukemia, lymphoma, autoimmune diseases, and organ-transplant patients on pharmacological immunosuppression were particularly at risk. Fungal thyroiditis was diagnosed at autopsy as part of disseminated infection in a substantial number of patients without clinical manifestations and laboratory evidence of thyroid dysfunction. Local signs and symptoms of infection were indistinguishable from other infectious thyroiditis and included fever, anterior cervical pain, thyroid enlargement sometimes associated with dysphagia and dysphonia, and clinical and laboratory features of transient hyperthyroidism due to the release of thyroid hormone from follicular cell damage, followed by residual hypothyroidism. Antemortem diagnosis of fungal thyroiditis was made by direct microscopy and culture of a fine-needle aspirate, or/and biopsy in most cases. Since most patients with fungal thyroiditis had disseminated fungal infection with delay in diagnosis and treatment, the overall mortality was high.