Fernando Leal

• Biology
• Professor (Full) at University of Salamanca

Approximately 150 fungal species are considered as primary pathogens of humans and animals[...]

One of the most important features that enables Aspergillus fumigatus to grow within a susceptible individual and to cause disease is its ability to obtain Zn²⁺ ions from the extremely zinc-limited environment provided by host tissues. Zinc uptake from this source in A. fumigatus relies on ZIP transporters encoded by the zrfA, zrfB and zrfC genes....

Aspergillus fumigatus is able to invade and grow in the lungs of immunosuppressed individuals and causes invasive pulmonary aspergillosis. The concentration of free zinc in living tissues is much lower than that required for optimal fungal growth in vitro because most of it is tightly bound to proteins. To obtain efficiently zinc from a living host...

Aspergillus fumigatus can invade the lungs of immunocompromised individuals causing a life-threatening disease called invasive pulmonary aspergillosis (IPA). To grow in the lungs, A. fumigatus obtains from the host all nutrients, including zinc. In living tissues, however, most zinc is tightly bound to zinc-binding proteins. Moreover, during infect...

Aspergillus fumigatus has three zinc transporter-encoding genes whose expression is regulated by both pH and the environmental concentration of zinc. We have previously reported that the zrfA and zrfB genes of A. fumigatus are transcribed at higher levels and are required for fungal growth under acidic zinc-limiting conditions whereas they are disp...

The ZrfA and ZrfB transporters are components of a zinc-uptake system of Aspergillus fumigatus that mainly operates under acidic, zinc-limiting conditions. Expression of the genes zrfA and zrfB is up-regulated by the transcriptional activator ZafA in both acidic and neutral, zinc-limiting media. The transcription of zafA is not influenced by PacC,...

The ZrfA and ZrfB transporters are components of a zinc-uptake system of Aspergillus fumigatus that mainly operates under acidic, zinc-limiting conditions. Expression of the genes zrfA and zrfB is up-regulated by the transcriptional activator ZafA in both acidic and neutral, zinc-limiting media. The transcription of zafA is not influenced by PacC,...

In Aspergillus fumigatus, the regulation of zinc homeostasis is strongly influenced by environmental pH. Thus, the study of zinc-regulated gene expression in A. fumigatus requires controlling variations in culture pH, as this may affect zinc availability. However, depending on the nitrogen source, the pH of the culture can change dramatically over...

We have previously shown that Aspergillus fumigatus is able to grow in zinc-limiting media and that this ability is regulated at transcriptional level by both the availability of zinc and pH. When A. fumigatus grows as a pathogen, it must necessarily obtain zinc from the zinc-limiting environment provided by host tissue. Accordingly, the regulation...

In Aspergillus fumigatus, the regulation of zinc homeostasis is strongly influenced by environmental pH. Thus, the study of zinc-regulated gene expression in A. fumigatus requires controlling variations in culture pH, as this may affect zinc availability. However, depending on the nitrogen source, the pH of the culture can change dramatically over...

Zinc is an essential micronutrient that cells must obtain from the environment in order to develop their normal growth. Previous work performed at our laboratory showed that the synthesis of immunodominant antigens from Aspergillus spp., including A. fumigatus, was up-regulated by a low environmental concentration of zinc. These results suggested t...

The xylanase Xys1L from Streptomyces halstedii JM8 is known to be processed extracellularly, to produce a protein of 33.7 kDa, Xys1S, that retains catalytic activity but not its cellulose-binding capacity. This paper demonstrates that at least five serine proteases isolated from Streptomyces spp. have the ability to process the xylanase Xys1L. The...

Streptomyces development is a complex process that eventually finishes with the formation of individual unigenomic spores from the aerial hyphae. Intraspecific and interspecific signals must play a key role in triggering or blocking this process. Here we show that interaction between two types of microorganisms, Streptomyces and yeasts, leads to al...

Detailed differential scanning calorimetry (DSC), steady‐state tryptophan fluorescence and far‐UV and visible CD studies, together with enzymatic assays, were carried out to monitor the thermal denaturation of horseradish peroxidase isoenzyme c (HRP c ) at pH 3.0. The spectral parameters were complementary to the highly sensitive but integral metho...

Aspergillus nidulans catalase B (CatB) was purified to homogeneity and characterized as a hydroperoxidase which resembles typical catalases in some physicochemical characteristics: (1) it has an apparent molecular weight of 360000 and is composed of four glycosylated subunits, (2) it has hydrophobic properties as revealed by extractability in ethan...

ASPND1 and ASPF2 are immunodominant antigens from Aspergillus nidulans and A. fumigatus, respectively, that are readily synthesized in infections in the human host, as demonstrated by their reactivity with more than 80% of sera from patients with aspergilloma or allergic bronchopulmonary aspergillosis. We demonstrate here that both antigens are exc...

A 996 bp Aspergillus nidulans cDNA encoding the ASPND1 immunodominant antigen was cloned and expressed in Escherichia coli as a fusion protein with the enzyme glutathione S-transferase (GST) from Schistosoma japonicum. The GST-ASPND1 fusion protein was purified from isolated bacterial inclusion bodies by preparative SDS-PAGE. After cleavage with th...

Aspergillus fumigatus possesses two catalases (described as fast and slow on the basis of their electrophoretic mobility). The slow catalase has been recognized as a diagnostic antigen for aspergillosis in immunocompetent patients. The antigenic catalase has been purified. The enzyme is a tetrameric protein composed of 90-kDa subunits. The correspo...

Thermal transitions in pig erythrocyte ghosts were studied by differential scanning calorimetry and thermal gel analysis (TGA). Heating of the suspension of pig erythrocyte ghosts induced at least six thermodynamically irreversible transitions. Each of these transitions is believed to be due to a localized structural transition induced by thermal s...

For the first time, an immunodominant Aspergillus nidulans antigen (ASPND1) consistently reactive with serum samples from aspergilloma patients has been purified and characterized, and its coding gene (aspnd1) has been cloned and sequenced. ASPND1 is a glycoprotein with four N-glycosidically-bound sugar chains (around 2.1 kDa each) which are not ne...

At present there are no accepted criteria to assess the usefulness of Western blot assays for the serodiagnosis of aspergilloma. An Aspergillus fumigatus cytosolic fraction complex (CFC) composed of four proteins (p90, p60, p40, and p37) has been identified. The usefulness of Western blotting with CFC antigens for the serodiagnosis of aspergilloma...

We have identified, purified, and characterized structurally and functionally a 90-kDa immunodominant antigen associated with the water-soluble fraction of Aspergillus fumigatus. This antigen is recognized by 90.3% of serum samples from patients with aspergilloma and should be considered either by itself or better in combination with other purified...

Cytosolic fractions of mycelial extracts from Aspergillus nidulans, A. flavus, and three different isolates of A. fumigatus, grown to stationary phase in Czapek-Dox-AOAC medium, were tested by immunoblotting for the presence of antigens reactive to 80 serum samples from aspergilloma patients. Fifty control serum samples were used to determine the s...

The influence of culture medium and time and temperature of growth on the appearance of Aspergillus nidulans antigens was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by silver staining or Western blot (immunoblot), of the proteins present in total cellular extracts or culture supernatants. Samples in the expone...

Cell‐free extracts of the asco‐mycetous fungus Aspergillus nidulans were separated into three subcellular fractions: cell walls, total membranes and cytosol, and two different immunization protocols were used to raise antibodies against them in 12 New Zealand rabbits. The immune response was followed over time by dot and Western blot analyses to de...

Aspergillus nidulans is an ascomycetous fungus that reproduces asexually by forming multicellular conidiophores and uninucleate spores called conidia. These elements constitute the main vehicle for the transmission of this and other pathogenic Aspergillus species and are the starting point of the different forms of aspergillosis. In order to use A....

A FITC-dextran internalization assay with Saccharomyces cerevisiae as positive control was used to determine whether fluid-phase endocytosis is a general characteristic of yeasts. Schizosaccharomyces pombe, Pichia polymorpha, Kluyveromyces phaseolosporus, Yarrowia lipolytica and Candida albicans were clearly positive, whereas results obtained with...

The v-sis oncogene encodes a protein structurally and functionally related to human platelet-derived growth factor (PDGF). In the present studies, we show that the primary translational product of the human sis proto-oncogene is a 26-kd protein, p26c-sis. This product is processed to yield a disulfide-linked homodimer, p56c-sis, which is further pr...

A scheme for partial purification of biologically active v-sis-coded protein from cells transformed with simian sarcoma virus (SSV) has made possible a functional comparison of the transforming protein with platelet-derived growth factor (PDGF). The SSV-transforming gene product is capable of specifically binding PDGF receptors, stimulating tyrosin...

Yeast 1,3-beta-D-glucan synthetase (EC 2.4.1.34) activity is modulated by endogenous factors obtained by the extraction of different subcellular fractions with hot water. Cell wall fractions were enriched in activators while supernatant fractions also contained appreciable amounts of inhibitors. The action of these compounds requires the presence o...

The v-sis transforming gene encodes the woolly monkey homologue of human platelet-derived growth factor (PDGF) polypeptide 2. After its synthesis on membrane bound polyribosomes, the glycosylated precursor dimerizes in the endoplasmic reticulum and travels through the Golgi apparatus. At the cell periphery, the precursor is processed to yield a dim...

Yeast beta(1--3) glucan synthetase is stimulated and stabilized by EDTA. Sucrose protects the enzyme from self-inactivation. Preincubation of cell free extracts at low sucrose concentrations indicates a slow transition of the enzyme towards dissociation. Transition kinetics at 30 degrees C and 0 degrees C in the presence and in the absence of sucro...

The molecular structure of the plasma membrane of the haploid strain Saccharomyces cerevisiae X-2180 1 A has been studied by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis. Protein and glycoprotein components have been identified and their apparent Mr determined. A glycoprotein showing an apparent Mr of 27500 has been shown to b...