Open AccessArticle
Estimated Burden of Serious Fungal Infections in Mozambique
J. Fungi 2018, 4(3), 75; https://doi.org/10.3390/jof4030075 (registering DOI) -
Abstract
Mozambique is a sub-Saharan African country with limited information on the burden of fungal disease. We estimate the burden of serious fungal infections for the general healthy population and for those at risk, including those infected with HIV, patients with asthma, as well
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Mozambique is a sub-Saharan African country with limited information on the burden of fungal disease. We estimate the burden of serious fungal infections for the general healthy population and for those at risk, including those infected with HIV, patients with asthma, as well as those under intensive care. We consult the Mozambican National Institute of Statistics Population and Housing Census report to obtain denominators for different age groups. We use modelling and HIV data to estimate the burdens of Pneumocystis jirovecii pneumonia (PCP), Cryptococcal meningitis (CM) and candidiasis. Asthma, chronic obstructive pulmonary disease and tuberculosis data were used to estimate the burden of allergic bronchopulmonary aspergillosis (ABPA) and chronic pulmonary aspergillosis (CPA). In 2016, the Mozambique population was 26.4 million with 1.8 million people reported to be HIV-infected. Estimated annual incidence of fungal infections was: 33,380 PCP, 18,640 CM and 260,025 oral and oesophageal candidiasis cases. Following pulmonary tuberculosis, estimated numbers of people having chronic pulmonary aspergillosis (prevalence) and allergic bronchopulmonary aspergillosis complicating asthma are 18,475 and 15,626, respectively. Tinea capitis is common in children with over 1.1 million probably affected. We also highlight from studies in progress of high incidences of Histoplasmosis, CM and Pneumocystis jirovecii in adult HIV-infected patients. Prospective epidemiology studies with sensitive diagnostics are required to validate these estimates. Full article
Open AccessEditorial
Special Issue: Candida and Candidiasis
J. Fungi 2018, 4(3), 74; https://doi.org/10.3390/jof4030074 -
Abstract
This special issue highlights emerging topics related to Candida, the most prevalent fungal pathogen in the hospital setting. The advantages and limitations of new, non-culture based diagnostic techniques are discussed. The issue reviews mammalian and non-mammalian infection models. The manuscripts present updates
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This special issue highlights emerging topics related to Candida, the most prevalent fungal pathogen in the hospital setting. The advantages and limitations of new, non-culture based diagnostic techniques are discussed. The issue reviews mammalian and non-mammalian infection models. The manuscripts present updates on several molecular mechanisms of pathogenicity, including filamentation, biofilm formation, and phospholipid production. Full article
Open AccessReview
Recent Advances in the Treatment of Scedosporiosis and Fusariosis
J. Fungi 2018, 4(2), 73; https://doi.org/10.3390/jof4020073 -
Abstract
Species of Scedosporium and Fusarium are considered emerging opportunistic pathogens, causing invasive fungal diseases in humans that are known as scedosporiosis and fusariosis, respectively. These mold infections typically affect patients with immune impairment; however, cases have been reported in otherwise healthy individuals. Clinical
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Species of Scedosporium and Fusarium are considered emerging opportunistic pathogens, causing invasive fungal diseases in humans that are known as scedosporiosis and fusariosis, respectively. These mold infections typically affect patients with immune impairment; however, cases have been reported in otherwise healthy individuals. Clinical manifestations vary considerably, ranging from isolated superficial infection to deep-seated invasive infection—affecting multiple organs—which is often lethal. While there have been a number of advances in the detection of these infections, including the use of polymerase chain reaction (PCR) and matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS), diagnosis is often delayed, leading to substantial morbidity and mortality. Although the optimal therapy is controversial, there have also been notable advances in the treatment of these diseases, which often depend on a combination of antifungal therapy, reversal of immunosuppression, and in some cases, surgical resection. In this paper, we review these advances and examine how the management of scedosporiosis and fusariosis may change in the near future. Full article
Open AccessReview
Vitamin Biosynthesis as an Antifungal Target
J. Fungi 2018, 4(2), 72; https://doi.org/10.3390/jof4020072 -
Abstract
The large increase in the population of immunosuppressed patients, coupled with the limited efficacy of existing antifungals and rising resistance toward them, have dramatically highlighted the need to develop novel drugs for the treatment of invasive fungal infections. An attractive possibility is the
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The large increase in the population of immunosuppressed patients, coupled with the limited efficacy of existing antifungals and rising resistance toward them, have dramatically highlighted the need to develop novel drugs for the treatment of invasive fungal infections. An attractive possibility is the identification of possible drug targets within essential fungal metabolic pathways not shared with humans. Here, we review the vitamin biosynthetic pathways (vitamins A–E, K) as candidates for the development of antifungals. We present a set of ranking criteria that identify the vitamin B2 (riboflavin), B5 (pantothenic acid), and B9 (folate) biosynthesis pathways as being particularly rich in new antifungal targets. We propose that recent scientific advances in the fields of drug design and fungal genomics have developed sufficiently to merit a renewed look at these pathways as promising sources for the development of novel classes of antifungals. Full article
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Open AccessArticle
The Caryopsis of Red-Grained Rice Has Enhanced Resistance to Fungal Attack
J. Fungi 2018, 4(2), 71; https://doi.org/10.3390/jof4020071 -
Abstract
Seed persistence in the soil is threatened by microorganisms, but the seed coat helps protect the seed from them. Although modern rice (Oryza sativa L.) cultivars have a whitish caryopsis, some varieties have a red caryopsis coat, a trait typical of wild
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Seed persistence in the soil is threatened by microorganisms, but the seed coat helps protect the seed from them. Although modern rice (Oryza sativa L.) cultivars have a whitish caryopsis, some varieties have a red caryopsis coat, a trait typical of wild Oryza species. The red colour is due to the oxidation of proanthocyanidins, a class of flavonoids that is found in the outer layers of the seed in many species. We aimed to assess whether these natural compounds (proanthocyanidins and proanthocyanidin-derived pigment) have some protective effect against microbial attacks. Dehulled caryopses of white-grained and red-grained rice genotypes were employed to assay fungal infection. Specifically, three white-grained rice cultivars (Perla, Augusto, and Koral) and three red-grained rice varieties (Perla Rosso, Augusto Rosso, and Koral Rosso) were used. In a first test, the caryopses were infected with Epicoccum nigrum at 10 °C, and seedling growth was then assessed at 30 °C. In a second test, the degree of infection by the mycotoxigenic fungus Fusarium sporotrichioides was assayed by measuring the accumulation of T-2/HT-2 toxins in the caryopses. Infection was performed at 10 °C to prevent rice germination while allowing fungal growth. In both the tests, red caryopses showed reduced, or delayed, infection with respect to white ones. One black-grained cultivar (Venere) was assayed for the accumulation of T-2/HT-2 toxins as well, with results corresponding to those of the red-grained rice varieties. We argue that the red pigment accumulating in the caryopsis coat, and/or the proanthocyanidins associated with it, provides a protective barrier against challenging microorganisms. Full article
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Open AccessArticle
Antiplasmodial Properties and Cytotoxicity of Endophytic Fungi from Symphonia globulifera (Clusiaceae)
J. Fungi 2018, 4(2), 70; https://doi.org/10.3390/jof4020070 -
Abstract
There is continuing need for new and improved drugs to tackle malaria, which remains a major public health problem, especially in tropical and subtropical regions of the world. Natural products represent credible sources of new antiplasmodial agents for antimalarial drug development. Endophytes that
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There is continuing need for new and improved drugs to tackle malaria, which remains a major public health problem, especially in tropical and subtropical regions of the world. Natural products represent credible sources of new antiplasmodial agents for antimalarial drug development. Endophytes that widely colonize healthy tissues of plants have been shown to synthesize a great variety of secondary metabolites that might possess antiplasmodial benefits. The present study was carried out to evaluate the antiplasmodial potential of extracts from endophytic fungi isolated from Symphonia globulifera against a chloroquine-resistant strain of Plasmodium falciparum (PfINDO). Sixty-one fungal isolates with infection frequency of 67.77% were obtained from the bark of S. globulifera. Twelve selected isolates were classified into six different genera including Fusarium, Paecilomyces, Penicillium, Aspergillus, Mucor, and Bipolaris. Extracts from the 12 isolates were tested against PfINDO, and nine showed good activity (IC50 < 10 μg·mL−1) with three fungi including Paecilomyces lilacinus (IC50 = 0.44 μg·mL−1), Penicillium janthinellum (IC50 = 0.2 μg·mL−1), and Paecilomyces sp. (IC50 = 0.55 μg·mL−1) showing the highest promise. These three isolates were found to be less cytotoxic against the HEK293T cell line with selectivity indices ranging from 24.52 to 70.56. Results from this study indicate that endophytic fungi from Symphonia globulifera are promising sources of hit compounds that might be further investigated as novel drugs against malaria. The chemical investigation of active extracts is ongoing. Full article
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Open AccessArticle
Restoring Waning Production of Volatile Organic Compounds in the Endophytic Fungus Hypoxylon sp. (BS15)
J. Fungi 2018, 4(2), 69; https://doi.org/10.3390/jof4020069 -
Abstract
Certain endophytic fungi belonging to the Hypoxylon genus have recently been found to produce volatile organic compounds (VOCs) that have potential relevance as hydrocarbon fuels. Here, a recently discovered Hypoxylon sp. (BS15) was demonstrated to also produce VOCs, but with diminished VOC production
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Certain endophytic fungi belonging to the Hypoxylon genus have recently been found to produce volatile organic compounds (VOCs) that have potential relevance as hydrocarbon fuels. Here, a recently discovered Hypoxylon sp. (BS15) was demonstrated to also produce VOCs, but with diminished VOC production after an extended period of in vitro growth. Restoring VOC production was partially achieved by growing BS15 in growth media containing finely ground woody tissue from the original host plant (Taxodium distichum). In an effort to isolate VOC production modulators, extracts from this woody tissue were made by sequentially extracting with dichloromethane, methanol, and water. Both the dichloromethane and water extracts were found to modulate VOC production, while the methanol extract had no effect. Surprisingly, the woody tissue remaining after exhaustive extraction was also shown to act as a VOC production modulator when included in the growth media, with changes observed in the production of four compounds. This woody tissue also induced production of two compounds not observed in the original BS15 extract. Filter paper had the same modulating effect as exhaustively extracted woody tissue, suggesting the modulation was perhaps due to cellulose degradation products. Overall, this study demonstrated that VOC production in BS15 can be influenced by multiple compounds in the woody tissue rather than a single modulator. Full article
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Open AccessReview
Conserved and Divergent Functions of the cAMP/PKA Signaling Pathway in Candida albicans and Candida tropicalis
J. Fungi 2018, 4(2), 68; https://doi.org/10.3390/jof4020068 -
Abstract
Fungal species undergo many morphological transitions to adapt to changing environments, an important quality especially in fungal pathogens. For decades, Candida albicans has been one of the most prevalent human fungal pathogens, and recently, the prevalence of Candida tropicalis as a causative agent
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Fungal species undergo many morphological transitions to adapt to changing environments, an important quality especially in fungal pathogens. For decades, Candida albicans has been one of the most prevalent human fungal pathogens, and recently, the prevalence of Candida tropicalis as a causative agent of candidiasis has increased. In C. albicans, the ability to switch between yeast and hyphal forms is thought to be a key virulence factor and is regulated by multiple signaling cascades—including the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA), calcineurin, high-osmolarity glycerol (HOG), and mitogen-activated protein kinases (MAPK) signaling pathways—upon receiving environmental cues. The cAMP/PKA signaling pathway also triggers white-opaque switching in C. albicans. However, studies on C. tropicalis morphogenesis are limited. In this minireview, we discuss the regulation of the yeast-hypha transition, virulence, and white-opaque switching through the cAMP/PKA pathway in the closely related species C. albicans and C. tropicalis. Full article
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Open AccessReview
Candida glabrata’s Genome Plasticity Confers a Unique Pattern of Expressed Cell Wall Proteins
J. Fungi 2018, 4(2), 67; https://doi.org/10.3390/jof4020067 -
Abstract
Candida glabrata is the second most common cause of candidemia, and its ability to adhere to different host cell types, to microorganisms, and to medical devices are important virulence factors. Here, we consider three characteristics that confer extraordinary advantages to C. glabrata within
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Candida glabrata is the second most common cause of candidemia, and its ability to adhere to different host cell types, to microorganisms, and to medical devices are important virulence factors. Here, we consider three characteristics that confer extraordinary advantages to C. glabrata within the host. (1) C. glabrata has a large number of genes encoding for adhesins most of which are localized at subtelomeric regions. The number and sequence of these genes varies substantially depending on the strain, indicating that C. glabrata can tolerate high genomic plasticity; (2) The largest family of CWPs (cell wall proteins) is the EPA (epithelial adhesin) family of adhesins. Epa1 is the major adhesin and mediates adherence to epithelial, endothelial and immune cells. Several layers of regulation like subtelomeric silencing, cis-acting regulatory regions, activators, nutritional signaling, and stress conditions tightly regulate the expression of many adhesin-encoding genes in C. glabrata, while many others are not expressed. Importantly, there is a connection between acquired resistance to xenobiotics and increased adherence; (3) Other subfamilies of adhesins mediate adherence to Candida albicans, allowing C. glabrata to efficiently invade the oral epithelium and form robust biofilms. It is noteworthy that every C. glabrata strain analyzed presents a unique pattern of CWPs at the cell surface. Full article
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Open AccessArticle
An In Vitro Model for Candida albicans–Streptococcus gordonii Biofilms on Titanium Surfaces
J. Fungi 2018, 4(2), 66; https://doi.org/10.3390/jof4020066 -
Abstract
The oral cavity serves as a nutrient-rich haven for over 600 species of microorganisms. Although many are essential to maintaining the oral microbiota, some can cause oral infections such as caries, periodontitis, mucositis, and endodontic infections, and this is further exacerbated with dental
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The oral cavity serves as a nutrient-rich haven for over 600 species of microorganisms. Although many are essential to maintaining the oral microbiota, some can cause oral infections such as caries, periodontitis, mucositis, and endodontic infections, and this is further exacerbated with dental implants. Most of these infections are mixed species in nature and associated with a biofilm mode of growth. Here, after optimization of different parameters including cell density, growth media, and incubation conditions, we have developed an in vitro model of C. albicans–S. gordonii mixed-species biofilms on titanium discs that is relevant to infections of peri-implant diseases. Our results indicate a synergistic effect for the development of biofilms when both microorganisms were seeded together, confirming the existence of beneficial, mutualistic cross-kingdom interactions for biofilm formation. The morphological and architectural features of these dual-species biofilms formed on titanium were determined using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Mixed biofilms formed on titanium discs showed a high level of resistance to combination therapy with antifungal and antibacterial drugs. This model can serve as a platform for further analyses of complex fungal/bacterial biofilms and can also be applied to screening of new drug candidates against mixed-species biofilms. Full article
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Open AccessArticle
Antifungal Activities of Volatile Secondary Metabolites of Four Diaporthe Strains Isolated from Catharanthus roseus
J. Fungi 2018, 4(2), 65; https://doi.org/10.3390/jof4020065 -
Abstract
Four endophytic fungi were isolated from the medicinal plant, Catharanthus roseus, and were identified as Diaporthe spp. with partial translation elongation factor 1-alpha (TEF1), beta-tubulin (TUB), histone H3 (HIS), calmodulin (CAL) genes, and rDNA
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Four endophytic fungi were isolated from the medicinal plant, Catharanthus roseus, and were identified as Diaporthe spp. with partial translation elongation factor 1-alpha (TEF1), beta-tubulin (TUB), histone H3 (HIS), calmodulin (CAL) genes, and rDNA internal transcribed spacer (ITS) region (TEF1-TUB-HIS--CAL-ITS) multigene phylogeny suggested for species delimitation in the Diaporthe genus. Each fungus produces a unique mixture of volatile organic compounds (VOCs) with an abundant mixture of terpenoids analyzed by headspace solid-phase microextraction (SPME) fiber-GC/MS. These tentatively-detected terpenes included α-muurolene, β-phellandrene, γ-terpinene, and α-thujene, as well as other minor terpenoids, including caryophyllene, patchoulene, cedrene, 2-carene, and thujone. The volatile metabolites of each isolate showed antifungal properties against a wide range of plant pathogenic test fungi and oomycetes, including Alternaria alternata, Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium graminearum, and Phytophthora cinnamomi. The growth inhibition of the pathogens varied between 10% and 60% within 72 h of exposure. To our knowledge, the endophytic Diaporthe-like strains are first reported from Catharanthus roseus. VOCs produced by each strain of the endophytic Diaporthe fungi were unique components with dominant monoterpenes comparing to known Diaporthe fungal VOCs. A discussion is presented on the inhibitive bioactivities of secondary metabolites among endophytic Diaporthe fungi and this medicinal plant. Full article
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Open AccessArticle
Repeated Exposition to Mercury (II) Chloride Enhances Susceptibility to S. schenckii sensu stricto Infection in Mice
J. Fungi 2018, 4(2), 64; https://doi.org/10.3390/jof4020064 -
Abstract
Sporotrichosis is a subcutaneous mycosis that has re-emerged in several tropical and subtropical regions over the last decades. Growing findings suggest that the interplay of host, pathogen, and environment has a determinant effect on the diversity, local distribution, and virulence of Sporothrix schenckii
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Sporotrichosis is a subcutaneous mycosis that has re-emerged in several tropical and subtropical regions over the last decades. Growing findings suggest that the interplay of host, pathogen, and environment has a determinant effect on the diversity, local distribution, and virulence of Sporothrix schenckii sensu lato, the etiologic agent. Among the environmental factors, we have studied the potential role of repeated exposures to mercury (Hg), a known immunotoxic xenobiotic that is widely used in gold mining regions where sporotrichosis outbreaks are frequently reported. In this study, male Swiss mice received subcutaneous injections of either 300 or 1200 µg/kg of mercury (II) chloride (HgCl2) for 14 days, three times a week. A control group was injected with the vehicle Phosphate Buffered Saline (PBS). Treatment with HgCl2 impaired several immunologic parameters that are involved in host response to Sporothrix infection, such as the production of TNFα, IL-1, and nitric oxide by macrophages, and Th1/Th2/Th17 populations and their respective cytokines. The consequences of these effects on the host resistance to S. schenckii infection were subsequently evaluated. Hg-exposed mice exhibited a higher fungal load in the fungal inoculation site associated to systemic dissemination to spleen and liver on 14 days post-infection and a higher production of specific IgG1 and mild reduction of IgG2a. These findings suggest that repeated exposition to Hg enhances susceptibility to S. schenckii infection in mice and can be a factor associated to sporotrichosis outbreaks in endemic and highly Hg-polluted areas. Full article
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Open AccessArticle
Alternaria and Fusarium Fungi: Differences in Distribution and Spore Deposition in a Topographically Heterogeneous Wheat Field
J. Fungi 2018, 4(2), 63; https://doi.org/10.3390/jof4020063 -
Abstract
Fusarium spp. and Alternaria spp., two genera of filamentous fungi, are common colonizers of the wheat phyllosphere. Both can be pathogenic and produce mycotoxins that are harmful to consumers. Their in-field infection dynamics have been a focus for the development of new control
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Fusarium spp. and Alternaria spp., two genera of filamentous fungi, are common colonizers of the wheat phyllosphere. Both can be pathogenic and produce mycotoxins that are harmful to consumers. Their in-field infection dynamics have been a focus for the development of new control strategies. We analysed the abundance on plant ears and spore deposition patterns of Fusarium spp. and Alternaria spp. in a topographically heterogeneous field. Abundances were assessed genetically, using qPCR-based techniques, and passive spore traps were installed for quantifying the spore deposition at different plant heights. Data loggers were placed to measure the differences in microclimate across the field. Results indicate different distribution and spore deposition patterns for the two fungi. Fusarium spp. spore and genetic abundances were higher in spots with a more humid and colder under-canopy microclimate. Alternaria spp. showed the opposite trend for genetic abundance, while its spore deposition was not correlated to any of the microclimatic conditions and was more uniform across the field. Our study extends the knowledge on the dispersal and in-field infection dynamics of Fusarium spp. and Alternaria spp., important for a better understanding of the epidemiology of these wheat pathogens. It also illustrates that topographically heterogeneous fields are a suitable environment for studying the ecology of phyllosphere-colonizing fungi. Full article
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Open AccessReview
Sporotrichosis: From KOH to Molecular Biology
J. Fungi 2018, 4(2), 62; https://doi.org/10.3390/jof4020062 -
Abstract
Sporotrichosis is a cosmopolitan, chronic granulomatous mycosis, acquired by traumatic inoculation and caused by Sporothrix schenckii complex. Several methods of diagnostic are available, from KOH to molecular biology. In this review, we describe from the simplest (clinical diagnosis) to the most advanced
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Sporotrichosis is a cosmopolitan, chronic granulomatous mycosis, acquired by traumatic inoculation and caused by Sporothrix schenckii complex. Several methods of diagnostic are available, from KOH to molecular biology. In this review, we describe from the simplest (clinical diagnosis) to the most advanced diagnostic techniques (molecular biology). Full article
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Open AccessArticle
Estimated Burden of Serious Fungal Infections in Malawi
J. Fungi 2018, 4(2), 61; https://doi.org/10.3390/jof4020061 -
Abstract
Despite efforts to address the burden of fungal infections in Malawi, the prevalence and incidence remain largely unknown. We assessed the annual burden in the general population and among populations at high risk and fungal infection frequencies in each particular population to estimate
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Despite efforts to address the burden of fungal infections in Malawi, the prevalence and incidence remain largely unknown. We assessed the annual burden in the general population and among populations at high risk and fungal infection frequencies in each particular population to estimate the national incidence or prevalence. The Malawi population is approximately 17.7 million (2017), with 48% under 15 years of age. Approximately 8% of the population is HIV positive. The most common infections are present in HIV/AIDS patients, with oral candidiasis being the commonest. Life threatening infections among those with AIDS patients include cryptococcal meningitis (8200 cases) and Pneumocystis pneumonia (3690 cases). Pulmonary TB is common, but extra pulmonary TB is rare; an estimated 2329 people have chronic pulmonary aspergillosis after TB. Asthma is a significant problem in Malawi, with an estimated 680,000 adults affected (4.67%) and 14,010 cases of allergic bronchopulmonary aspergillosis (ABPA). Tinea capitis is estimated to be present in over 670,000 young people (21% of school age children). The annual incidence of fungal keratitis is difficult to estimate, but as cases are frequently seen in the eye department, is likely to be a minimum of 1825 (10.3/100,000) cases. Among the most serious infections, cryptococcal meningitis and Pneumocystis pneumonia are top of the list. Overall, some 1,338,523 (7.54%) people are affected by a serious fungal infection in Malawi. These basic estimates are limited, due to poor record keeping, and require epidemiological studies to validate or modify the substantial burden estimates. National surveillance of fungal infections is urgently needed. Full article
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Open AccessReview
Adhesins in Candida glabrata
J. Fungi 2018, 4(2), 60; https://doi.org/10.3390/jof4020060 -
Abstract
The human fungal pathogen Candida glabrata is causing more and more problems in hospitals, as this species shows an intrinsic antifungal drug resistance or rapidly becomes resistant when challenged with antifungals. C. glabrata only grows in the yeast form, so it is lacking
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The human fungal pathogen Candida glabrata is causing more and more problems in hospitals, as this species shows an intrinsic antifungal drug resistance or rapidly becomes resistant when challenged with antifungals. C. glabrata only grows in the yeast form, so it is lacking a yeast-to-hyphae switch, which is one of the main virulence factors of C. albicans. An important virulence factor of C. glabrata is its capacity to strongly adhere to many different substrates. To achieve this, C. glabrata expresses a large number of adhesin-encoding genes and genome comparisons with closely related species, including the non-pathogenic S. cerevisiae, which revealed a correlation between the number of adhesin-encoding genes and pathogenicity. The adhesins are involved in the first steps during an infection; they are the first point of contact with the host. For several of these adhesins, their importance in adherence to different substrates and subsequent biofilm formation was demonstrated in vitro or in vivo. In this review, we provide an overview of the role of C. glabrata adhesins during adhesion and biofilm formation both, under in vitro and in vivo conditions. Full article
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Open AccessReview
What We Do Not Know about Fungal Cell Adhesion Molecules
J. Fungi 2018, 4(2), 59; https://doi.org/10.3390/jof4020059 -
Abstract
There has been extensive research on structure and function of fungal cell adhesion molecules, but the most of the work has been about adhesins in Candida albicans and Saccharomyces cerevisiae. These yeasts are members of a single ascomycete order, and adhesion molecules from
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There has been extensive research on structure and function of fungal cell adhesion molecules, but the most of the work has been about adhesins in Candida albicans and Saccharomyces cerevisiae. These yeasts are members of a single ascomycete order, and adhesion molecules from the six other fungal phyla are only sparsely described in the literature. In these other phyla, most of the research is at the cellular level, rather than at the molecular level, so there has been little characterization of the adhesion molecules themselves. A catalog of known adhesins shows some common features: high Ser/Thr content, tandem repeats, N- and O-glycosylations, GPI anchors, dibasic sequence motifs, and potential amyloid-forming sequences. However, none of these features is universal. Known ligands include proteins and glycans on homologous cells and host cells. Existing and novel tools can exploit the availability of genome sequences to identify and characterize new fungal adhesins. These include bioinformatics tools and well-established yeast surface display models, which could be coupled with an adhesion substrate array. Thus, new knowledge could be exploited to answer key questions in fungal ecology, animal and plant pathogenesis, and roles of biofilms in infection and biomass turnover. Full article
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Open AccessArticle
Observations on the Early Establishment of Foliar Endophytic Fungi in Leaf Discs and Living Leaves of a Model Woody Angiosperm, Populus trichocarpa (Salicaceae)
J. Fungi 2018, 4(2), 58; https://doi.org/10.3390/jof4020058 -
Abstract
Fungal endophytes are diverse and widespread symbionts that occur in the living tissues of all lineages of plants without causing evidence of disease. Culture-based and culture-free studies indicate that they often are abundant in the leaves of woody angiosperms, but only a few
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Fungal endophytes are diverse and widespread symbionts that occur in the living tissues of all lineages of plants without causing evidence of disease. Culture-based and culture-free studies indicate that they often are abundant in the leaves of woody angiosperms, but only a few studies have visualized endophytic fungi in leaf tissues, and the process through which most endophytes colonize leaves has not been studied thoroughly. We inoculated leaf discs and the living leaves of a model woody angiosperm, Populus trichocarpa, which has endophytes that represent three distantly-related genera (Cladosporium, Penicillium, and Trichoderma). We used scanning electron microscopy and light microscopy to evaluate the timeline and processes by which they colonize leaf tissue. Under laboratory conditions with high humidity, conidia germinated on leaf discs to yield hyphae that grew epiphytically and incidentally entered stomata, but did not grow in a directed fashion toward stomatal openings. No cuticular penetration was observed. The endophytes readily colonized the interiors of leaf discs that were detached from living leaves, and could be visualized within discs with light microscopy. Although they were difficult to visualize within the interior of living leaves following in vivo inoculations, standard methods for isolating foliar endophytes confirmed their presence. Full article
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Open AccessOpinion
The Emergence of Endophytic Microbes and Their Biological Promise
J. Fungi 2018, 4(2), 57; https://doi.org/10.3390/jof4020057 -
Abstract
As is true with animal species, plants also have an associated microflora including endophytes as well as microbes associated with the phyllosphere and rhizosphere (plant surfaces) and this is considered the plant microbiome. However, those organisms within virtually all tissues and organs of
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As is true with animal species, plants also have an associated microflora including endophytes as well as microbes associated with the phyllosphere and rhizosphere (plant surfaces) and this is considered the plant microbiome. However, those organisms within virtually all tissues and organs of the plant are known as endophytes. Most often fungi are the most frequently recovered endophytes from plant tissues, but bacterial forms generally occur in greater numbers, but not in species varieties. The exact biological/biochemical role of the endophyte in the plant and how it interacts with the plant and other endophytes and plant associated organisms has not been intensely and carefully examined. However, this has not stopped investigators in exploring the direct utility of endophytes in boosting plant production, and discovering that endophytes can directly influence the plant to resist temperature extremes, drought, as well as the presence of disease causing organisms. Also, because of the relationships that endophytes seem to have with their host plants, they make a myriad of biologically active compounds some of which are classified as antibiotics, antioxidants, anticancer agents, volatile antimicrobial agents, immunosuppressive compounds, plant growth promoting agents, and insecticides. These endophytic compounds represent a wide range of organic molecules including terpenoids, peptides, carbohydrates, aromatics, hydrocarbons and others and it seems that these compounds may have a role in the host microbe relationship. Most recently and quite surprisingly, some endophytes have been discovered that make hydrocarbons of the types found in diesel and gasoline fuels. In addition, recently discovered are epigenetic factors relating to the biology and biochemistry of endophytes. Interestingly, only about 1–2% of the entire spectrum of 300,000 known plants have been studied for their endophyte composition. Additionally, only a few plants have ever been completely studied including all tissues for the microbes within them. Likewise, the vast majority of plants, including those in oceans and lower plant forms, have never been examined for their endophytes. Furthermore, endophytes representing the “microbiome” of world’s major food plants as they exist in their native “centers of origin” are largely unknown. This non-classical review is intended to provide background information on aspects of developments in endophyte biology and more importantly the identification of new questions in this field that need to be addressed. The review is primarily based on the author’s long held experience in this field. Full article
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Open AccessReview
Nodular Lymphangitis (Sporotrichoid Lymphocutaneous Infections). Clues to Differential Diagnosis
J. Fungi 2018, 4(2), 56; https://doi.org/10.3390/jof4020056 -
Abstract
Nodular lymphangitis, also known as sporotrichoid lymphocutaneous infections, is characterized by suppurative inflammatory nodules along the lymphatic vessels. This manifestation is classic of sporotrichosis, however, other infections such as nocardiosis, atypical mycobacteriosis, leishmaniasis, among others, can also express this clinical pattern. Sporotrichosis, which
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Nodular lymphangitis, also known as sporotrichoid lymphocutaneous infections, is characterized by suppurative inflammatory nodules along the lymphatic vessels. This manifestation is classic of sporotrichosis, however, other infections such as nocardiosis, atypical mycobacteriosis, leishmaniasis, among others, can also express this clinical pattern. Sporotrichosis, which often occurs in gardeners, remains the most recognized cause of nodular lymphangitis. The histopathological studies, as well as the culture are diagnostic standards of lesions that do not respond to empirical treatment. In this article, we will review the main causes of nodular lymphangitis or lymphocutaneous sporotrichoid infections. Full article
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