Sphingosine-1-phospate receptor 4 regulates passive systemic anaphylaxis in mice but is dispensable for canonical IgE-mediated responses in mast cells

Mast cells are key players in the development of inflammatory allergic reactions. Cross-linking of the high-affinity receptor for IgE (FcɛRI) on mast cells leads to the generation and secretion of the sphingolipid mediator, sphingosine-1-phosphate (S1P) which can in turn activate its G-protein coupled receptors on mast cells. Previous reports have identified the expression of two of the five receptors for S1P on mast cells, S1P1 and S1P2, with functions in IgE-receptor-mediated chemotaxis and degranulation, respectively. Here, we show that cultured human and mouse mast cells also express abundant message for the S1P4 receptor and demonstrate its presence at the plasma membrane in the human mast cell line LAD2. Genetic deletion of S1pr4 resulted in exacerbation of passive systemic anaphylaxis to IgE/anti-IgE in mice. However, exhaustive characterization of IgE-mediated responses in S1P4-deficient bone marrow and peritoneal mouse mast cells indicated that this receptor is dispensable for normal in vitro mast cell growth and responses to IgE-mediated activation including degranulation, cytokine/chemokine release and chemotaxis. Thus, we provide evidence that S1P4 modulates mast cell-mediated anaphylaxis in vivo in an unexpected manner that does not involve regulation of mast cell responsiveness to IgE stimulation.

Targeting Sphingosine Kinase Isoforms Effectively Reduces Growth and Survival of Neoplastic Mast Cells With D816V-KIT

Mastocytosis is a disorder resulting from an abnormal mast cell (MC) accumulation in tissues that is often associated with the D816V mutation in KIT, the tyrosine kinase receptor for stem cell factor. Therapies available to treat aggressive presentations of mastocytosis are limited, thus exploration of novel pharmacological targets that reduce MC burden is desirable. Since increased generation of the lipid mediator sphingosine-1-phosphate (S1P) by sphingosine kinase (SPHK) has been linked to oncogenesis, we studied the involvement of the two SPHK isoforms (SPHK1 and SPHK2) in the regulation of neoplastic human MC growth. While SPHK2 inhibition prevented entry into the cell cycle in normal and neoplastic human MCs with minimal effect on cell survival, SPHK1 inhibition caused cell cycle arrest in G2/M and apoptosis, particularly in D816V-KIT MCs. This was mediated via activation of the DNA damage response (DDR) cascade, including phosphorylation of the checkpoint kinase 2 (CHK2), CHK2-mediated M-phase inducer phosphatase 3 depletion, and p53 activation. Combination treatment of SPHK inhibitors with KIT inhibitors showed greater growth inhibition of D816V-KIT MCs than either inhibitor alone. Furthermore, inhibition of SPHK isoforms reduced the number of malignant bone marrow MCs from patients with mastocytosis and the growth of D816V-KIT MCs in a xenograft mouse model. Our results reveal a role for SPHK isoforms in the regulation of growth and survival in normal and neoplastic MCs and suggest a regulatory function for SPHK1 in the DDR in MCs with KIT mutations. The findings also suggest that targeting the SPHK/S1P axis may provide an alternative to tyrosine kinase inhibitors, alone or in combination, for the treatment of aggressive mastocytosis and other hematological malignancies associated with the D816V-KIT mutation.

Modulating the immune system through nanotechnology

Nowadays, nanotechnology-based modulation of the immune system is presented as a cutting-edge strategy, which may lead to significant improvements in the treatment of severe diseases. In particular, efforts have been focused on the development of nanotechnology-based vaccines, which could be used for immunization or generation of tolerance. In this review, we highlight how different immune responses can be elicited by tuning nanosystems properties. In addition, we discuss specific formulation approaches designed for the development of anti-infectious and anti-autoimmune vaccines, as well as those intended to prevent the formation of antibodies against biologicals.

Interaction of DJ-1 with Lyn is essential for IgE-mediated stimulation of human mast cells

BACKGROUND

DJ-1 is a redox-sensitive protein with multiple roles in cell homeostasis, levels of which are altered in patients with mast cell (MC)-related disorders. However, whether DJ-1 can regulate human MC function is unknown.

OBJECTIVE

We sought to investigate the potential role of DJ-1 in the responses of human MCs to antigen stimulation.

METHODS

DJ-1 was silenced in human CD34⁺-derived MCs and in the LAD2 MC line by using lentiviral short hairpin RNA constructs. Release of β-hexosaminidase, prostaglandin D₂, and GM-CSF and changes in reactive oxygen species levels were measured after FcεRI engagement. Enzymatic assays, sucrose density gradient centrifugation, immunoprecipitation, dot and Western blotting, and confocal imaging were performed for signaling, cellular localization, and coassociation studies.

RESULTS

DJ-1 knockdown substantially reduced mediator release, as well as Lyn kinase and spleen tyrosine kinase activation and signaling through mechanisms that appeared largely unrelated to DJ-1 antioxidant activity. Following FcεRI activation, nonoxidized rather than oxidized DJ-1 translocated to lipid rafts, where it associated with Lyn, an interaction that appeared critical for maximal Lyn activation and initiation of signaling. Using purified recombinant proteins, we demonstrated that DJ-1 directly bound to Lyn but not to other Src kinases, and this interaction was specific for human but not mouse proteins. In addition, DJ-1 reduced Src homology 2 domain-containing phosphatase 2 phosphatase activity by scavenging reactive oxygen species, thus preventing spleen tyrosine kinase dephosphorylation and perpetuating MC signaling.

CONCLUSION

We demonstrate a novel role for DJ-1 in the early activation of Lyn by FcεRI, which is essential for human MC responses and provides the basis for an alternative target in allergic disease therapy.

An optimized protocol for the generation and functional analysis of human mast cells from CD34+ enriched cell populations

The culture of mast cells from human tissues such a cord blood, peripheral blood or bone marrow aspirates has advanced our understanding of human mast cells (huMC) degranulation, mediator production and response to pharmacologic agents. However, existing methods for huMC culture tend to be laborious and expensive. Combining technical approaches from several of these protocols, we designed a simplified and more cost effective approach to the culture of mast cells from human cell populations including peripheral blood and cryopreserved cells from lymphocytapheresis. On average, we reduced by 30-50 fold the amount of culture media compared to our previously reported method, while the total MC number generated by this method (2.46±0.63×10⁶ vs. 2.4±0.28×10⁶, respectively, from 1.0×10⁸ lymphocytapheresis or peripheral blood mononuclear blood cells [PBMCs]) was similar to our previous method (2.36±0.70×10⁶), resulting in significant budgetary savings. In addition, we compared the yield of huMCs with or without IL-3 added to early cultures in the presence of stem cell factor (SCF) and interlukin-6 (IL-6) and found that the total MC number generated, while higher with IL-3 in the culture, did not reach statistical significance, suggesting that IL-3, often recommended in the culture of huMCs, is not absolutely required. We then performed a functional analysis by flow cytometry using standard methods and which maximized the data we could obtain from cultured cells. We believe these approaches will allow more laboratories to culture and examine huMC behavior going forward.

Gender Difference Among Admitted Patients with Bipolar Disorder in a Psychiatric Service During a Three-year Period

Introduction

Gender differences in bipolar disorder are becoming apparent, but have been less studied compared with major depression. The presentation, clinical features, course and evolution of bipolar disorder differ between men and women. Research data on these differences will help determine whether gender is important in influencing illness variables.

Objectives

Determine whether men and women with bipolar disorder have statistical significant differences in socio-demographic and clinical data.

Methods

Charts of all patients with a diagnosis of bipolar disorder admitted in the Coimbra Hospital and Universitary Center over a three-year period (between 2013 and 2015) were reviewed to gather data on socio-demographic, clinical and psychopathological variables to assess differences across genders. Statistical analysis of data with “SPSS21”.

Results

During a three-year period, 189 patients were admitted with bipolar disorder, the majority were female patients, with ages between 21 and 84 years old. The authors will analyse if there is any statistical significant difference between gender in the rate of bipolar I or II diagnoses, age at onset, symptom presentation, delay in diagnoses, number of depressive, or manic episodes, hospitalisations, involuntarily admissions, number of suicide attempts, co-morbidity rates, negative life events, family history and treatment options. Sociodemograpic characteristics will also be analysed.

Conclusion

Gender differences in bipolar disorder is a controversial issue in the literature. The importance of gender on the course and outcome in bipolar disorder has been widely acknowledged. The limited data suggest that the prevalence is similar between sexes but that the course of illness may be different.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Regulation of Reactive Oxygen Species and the Antioxidant Protein DJ-1 in Mastocytosis

Neoplastic accumulation of mast cells in systemic mastocytosis (SM) associates with activating mutations in the receptor tyrosine kinase KIT. Constitutive activation of tyrosine kinase oncogenes has been linked to imbalances in oxidant/antioxidant mechanisms in other myeloproliferative disorders. However, the impact of KIT mutations on the redox status in SM and the potential therapeutic implications are not well understood. Here, we examined the regulation of reactive oxygen species (ROS) and of the antioxidant protein DJ-1 (PARK-7), which increases with cancer progression and acts to lessen oxidative damage to malignant cells, in relationship with SM severity. ROS levels were increased in both indolent (ISM) and aggressive variants of the disease (ASM). However, while DJ-1 levels were reduced in ISM with lower mast cell burden, they rose in ISM with higher mast cell burden and were significantly elevated in patients with ASM. Studies on mast cell lines revealed that activating KIT mutations induced constant ROS production and consequent DJ-1 oxidation and degradation that could explain the reduced levels of DJ-1 in the ISM population, while IL-6, a cytokine that increases with disease severity, caused a counteracting transcriptional induction of DJ-1 which would protect malignant mast cells from oxidative damage. A mouse model of mastocytosis recapitulated the biphasic changes in DJ-1 and the escalating IL-6, ROS and DJ-1 levels as mast cells accumulate, findings which were reversed with anti-IL-6 receptor blocking antibody. Our findings provide evidence of increased ROS and a biphasic regulation of the antioxidant DJ-1 in variants of SM and implicate IL-6 in DJ-1 induction and expansion of mast cells with KIT mutations. We propose consideration of IL-6 blockade as a potential adjunctive therapy in the treatment of patients with advanced mastocytosis, as it would reduce DJ-1 levels making mutation-positive mast cells vulnerable to oxidative damage.

Sphingosine-1-phosphate Phosphatase 2 Regulates Pancreatic Islet β-Cell Endoplasmic Reticulum Stress and Proliferation

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite that regulates basic cell functions through metabolic and signaling pathways. Intracellular metabolism of S1P is controlled, in part, by two homologous S1P phosphatases (SPPases), 1 and 2, which are encoded by the Sgpp1 and Sgpp2 genes, respectively. SPPase activity is needed for efficient recycling of sphingosine into the sphingolipid synthesis pathway. SPPase 1 is important for skin homeostasis, but little is known about the functional role of SPPase 2. To identify the functions of SPPase 2 in vivo, we studied mice with the Sgpp2 gene deleted. In contrast to Sgpp1(-/-) mice, Sgpp2(-/-) mice had normal skin and were viable into adulthood. Unexpectedly, WT mice expressed Sgpp2 mRNA at high levels in pancreatic islets when compared with other tissues. Sgpp2(-/-) mice had normal pancreatic islet size; however, they exhibited defective adaptive β-cell proliferation that was demonstrated after treatment with either a high-fat diet or the β-cell-specific toxin, streptozotocin. Importantly, β-cells from untreated Sgpp2(-/-) mice showed significantly increased expression of proteins characteristic of the endoplasmic reticulum stress response compared with β-cells from WT mice, indicating a basal islet defect. Our results show that Sgpp2 deletion causes β-cell endoplasmic reticulum stress, which is a known cause of β-cell dysfunction, and reveal a juncture in the sphingolipid recycling pathway that could impact the development of diabetes.

Diminution of signal transducer and activator of transcription 3 signaling inhibits vascular permeability and anaphylaxis

BACKGROUND

During IgE-mediated immediate hypersensitivity reactions, vascular endothelial cells permeabilize in response to mast cell mediators. We have demonstrated previously that patients and mice with signal transducer and activator of transcription 3 (STAT3) mutations (autosomal dominant hyper-IgE syndrome [AD-HIES]) are partially protected from anaphylaxis.

OBJECTIVES

We sought to study the mechanism by which STAT3 contributes to anaphylaxis and determine whether small-molecule inhibition of STAT3 can prevent anaphylaxis.

METHODS

Using unaffected and STAT3-inhibited or genetic loss-of-function samples, we performed histamine skin prick tests, investigated the contribution of STAT3 to animal models of anaphylaxis, and measured endothelial cell permeability, gene and protein expression, and histamine receptor-mediated signaling.

RESULTS

Although mouse mast cell degranulation was minimally affected by STAT3 blockade, mast cell mediator-induced anaphylaxis was blunted in Stat3 mutant mice with AD-HIES and in wild-type mice subjected to small-molecule STAT3 inhibition. Histamine skin prick test responses were diminished in patients with AD-HIES. Human umbilical vein endothelial cells derived from patients with AD-HIES or treated with a STAT3 inhibitor did not signal properly through Src or cause appropriate dissolution of the adherens junctions made up of the proteins vascular endothelial-cadherin and β-catenin. Furthermore, we found that diminished STAT3 target microRNA17-92 expression in human umbilical vein endothelial cells from patients with AD-HIES is associated with increased phosphatase and tensin homolog (PTEN) expression, which inhibits Src, and increased E2F transcription factor 1 expression, which regulates β-catenin cellular dynamics.

CONCLUSIONS

These data demonstrate that STAT3-dependent transcriptional activity regulates critical components for the architecture and functional dynamics of endothelial junctions, thus permitting vascular permeability.

Vibratory Urticaria Associated with a Missense Variant in ADGRE2

Patients with autosomal dominant vibratory urticaria have localized hives and systemic manifestations in response to dermal vibration, with coincident degranulation of mast cells and increased histamine levels in serum. We identified a previously unknown missense substitution in ADGRE2 (also known as EMR2), which was predicted to result in the replacement of cysteine with tyrosine at amino acid position 492 (p.C492Y), as the only nonsynonymous variant cosegregating with vibratory urticaria in two large kindreds. The ADGRE2 receptor undergoes autocatalytic cleavage, producing an extracellular subunit that noncovalently binds a transmembrane subunit. We showed that the variant probably destabilizes an autoinhibitory subunit interaction, sensitizing mast cells to IgE-independent vibration-induced degranulation. (Funded by the National Institutes of Health.).

Neonatal exposure to amphetamine alters social affiliation and central dopamine activity in adult male prairie voles

The prairie vole (Microtus ochrogaster) is a socially monogamous rodent species that forms pair bonds after mating. Recent data have shown that amphetamine (AMPH) is rewarding to prairie voles as it induces conditioned place preferences. Further, repeated treatment with AMPH impairs social bonding in adult prairie voles through a central dopamine (DA)-dependent mechanism. The present study examined the effects of neonatal exposure to AMPH on behavior and central DA activity in adult male prairie voles. Our data show that neonatal exposure to AMPH makes voles less social in an affiliation test during adulthood, but does not affect animals' locomotor activity and anxiety-like behavior. Neonatal exposure to AMPH also increases the levels of tyrosine hydroxylase (TH) and DA transporter (DAT) mRNA expression in the ventral tegmental area (VTA) in the brain, indicating an increase in central DA activity. As DA has been implicated in AMPH effects on behavioral and cognitive functions, altered DA activity in the vole brain may contribute to the observed changes in social behavior.

Activated mast cells synthesize and release soluble ST2-a decoy receptor for IL-33

IL-33 released from damaged cells plays a central role in allergic inflammation by acting through its membrane-bound receptor, ST2 receptor (ST2L). IL-33 activity can be neutralized by the soluble spliced variant of ST2 (sST2) that has been associated with allergic inflammation but its source is not well defined. We investigated whether mast cells (MCs) are a significant source of sST2 following activation through FcεRI or ST2. We find that antigen and IL-33 induce substantial production and release of sST2 from human and mouse MCs in culture and do so synergistically when added together or in combination with stem cell factor. Moreover, increases in circulating sST2 during anaphylaxis in mice were dependent on the presence of MCs. Human MCs activated via FcεRI failed to generate IL-33 and IL-33 produced by mouse bone marrow-derived MCs was retained within the cells. Therefore, FcεRI-mediated sST2 production is independent of MC-derived IL-33 acting in an autocrine manner. These results are consistent with the conclusion that both mouse and human MCs when activated are a significant inducible source of sST2 but not IL-33 and thus have the ability to modulate the biologic impact of IL-33 produced locally by other cell types during allergic inflammation.

Distinct transcriptome profiles differentiate nonsteroidal anti-inflammatory drug-dependent from nonsteroidal anti-inflammatory drug-independent food-induced anaphylaxis

BACKGROUND

Lipid transfer protein (LTP), an abundant protein in fruits, vegetables, and nuts, is a common food allergen in Mediterranean areas causing diverse allergic reactions. Approximately 40% of food-related anaphylaxis induced by LTPs requires nonsteroidal anti-inflammatory drugs (NSAIDs) as a triggering cofactor.

OBJECTIVE

We sought to better understand the determinants of NSAID-dependent and NSAID-independent LTP-induced anaphylaxis (LTP-A).

METHODS

Selection of patients was based on a proved clinical history of NSAID-dependent or NSAID-independent anaphylaxis to LTPs, positive skin prick test response to LTPs, and serum LTP IgE. Whole-transcriptome (RNA sequencing) analysis of blood cells from 14 patients with NSAID-related LTP-A (NSAID-LTP-A), 7 patients with LTP-A, and 13 healthy control subjects was performed to identify distinct gene expression signatures.

RESULTS

Expression of genes regulating gastrointestinal epithelial renewal was altered in both patient sets, particularly in those with LTP-A, who also presented with gene expression profiles characteristic of an inflammatory syndrome. These included altered B-cell pathways, increased neutrophil activation markers, and increased reactive oxygen species levels. Increased expression of the IgG receptor (CD64) in patients with LTP-A was mirrored by the presence of LTP-specific IgG1 and IgG3. Conversely, patients with NSAID-LTP-A were characterized by reduced expression of IFN-γ-regulated genes and IFN-γ levels, as well as upregulated expression of adenosine receptor 3 (ADORA3) and genes related to adenosine metabolism.

CONCLUSIONS

Gene ontology analysis suggests disturbances in gut epithelial homeostasis in both groups with LTP-A, with potential integrity breaches in patients with LTP-A that might explain their distinct inflammatory signatures. Differential regulation in patients with LTP-A and those with NSAID-LTP-A of the IFN-γ pathway, IgG receptors, and ADORA3 might provide the pathogenic basis of their distinct responses.

Analyzing redox balance in a synthetic yeast platform to improve utilization of brown macroalgae as feedstock

Macroalgae have high potential to be an efficient, and sustainable feedstock for the production of biofuels and other more valuable chemicals. Attempts have been made to enable the co-fermentation of alginate and mannitol by Saccharomyces cerevisiae to unlock the full potential of this marine biomass. However, the efficient use of the sugars derived from macroalgae depends on the equilibrium of cofactors derived from the alginate and mannitol catabolic pathways. There are a number of strong metabolic limitations that have to be tackled before this bioconversion can be carried out efficiently by engineered yeast cells.

An analysis of the redox balance during ethanol fermentation from alginate and mannitol by Saccharomyces cerevisiae using metabolic engineering tools was carried out. To represent the strain designed for conversion of macroalgae carbohydrates to ethanol, a context-specific model was derived from the available yeast genome-scale metabolic reconstructions. Flux balance analysis and dynamic simulations were used to determine the flux distributions. The model indicates that ethanol production is determined by the activity of 4-deoxy-l-erythro-5-hexoseulose uronate (DEHU) reductase (DehR) and its preferences for NADH or NADPH which influences strongly the flow of cellular resources. Different scenarios were explored to determine the equilibrium between NAD(H) and NADP(H) that will lead to increased ethanol yields on mannitol and DEHU under anaerobic conditions. When rates of mannitol dehydrogenase and DehR_NADH tend to be close to a ratio in the range 1–1.6, high growth rates and ethanol yields were predicted. The analysis shows a number of metabolic limitations that are not easily identified through experimental procedures such as quantifying the impact of the cofactor preference by DEHU reductase in the system, the low flux into the alginate catabolic pathway, and a detailed analysis of the redox balance. These results show that production of ethanol and other chemicals can be optimized if a redox balance is achieved. A possible methodology to achieve this balance is presented. This paper shows how metabolic engineering tools are essential to comprehend and overcome this limitation.

•

We studied a strain designed for bioconversion of macroalgae sugars to ethanol.

•

A genome-scale model was used to simulate biomass and by-product formation.

•

The characterization of the current metabolic state of the strain was achieved.

•

Biofuel production depends on the redox balance derived from alginate and mannitol.

•

Flux split into DehR determines the redox balance, by-products and ethanol level.

Sphingosine-1-phosphate and other lipid mediators generated by mast cells as critical players in allergy and mast cell function

Sphingosine-1-phosphate (S1P), platelet activating factor (PAF) and eicosanoids are bioactive lipid mediators abundantly produced by antigen-stimulated mast cells that exert their function mostly through specific cell surface receptors. Although it has long been recognized that some of these bioactive lipids are potent regulators of allergic diseases, their exact contributions to disease pathology have been obscured by the complexity of their mode of action and the regulation of their metabolism. Indeed, the effects of such lipids are usually mediated by multiple receptor subtypes that may differ in their signaling mechanisms and functions. In addition, their actions may be elicited by cell surface receptor-independent mechanisms. Furthermore, these lipids may be converted into metabolites that exhibit different functionalities, adding another layer of complexity to their overall biological responses. In some instances, a second wave of lipid mediator synthesis by both mast cell and non-mast cell sources may occur late during inflammation, bringing about additional roles in the altered environment. New evidence also suggests that bioactive lipids in the local environment can fine-tune mast cell maturation and phenotype, and thus their responsiveness. A better understanding of the subtleties of the spatiotemporal regulation of these lipid mediators, their receptors and functions may aid in the pursuit of pharmacological applications for allergy treatments.

Estrogen increases the severity of anaphylaxis in female mice through enhanced endothelial nitric oxide synthase expression and nitric oxide production

BACKGROUND

Clinical observations suggest that anaphylaxis is more common in adult women compared with adult men, although the mechanistic basis for this sex bias is not well understood.

OBJECTIVES

We sought to document sex-dependent differences in a mouse model of anaphylaxis and explore the role of female sex hormones and the mechanisms responsible.

METHODS

Passive systemic anaphylaxis was induced in female and male mice by using histamine, as well as IgE or IgG receptor aggregation. Anaphylaxis was assessed by monitoring body temperature, release of mast cell mediators and/or hematocrit, and lung weight as a measure of vascular permeability. A combination of ovariectomy, estrogen receptor antagonism, and estrogen administration techniques were used to establish estrogen involvement.

RESULTS

Anaphylactic responses were more pronounced in female than male mice. The enhanced severity of anaphylaxis in female mice was eliminated after pretreatment with an estrogen receptor antagonist or ovariectomy but restored after administration of estradiol in ovariectomized mice, demonstrating that the sex-specific differences are due to the female steroid estradiol. Estrogen did not affect mast cell responsiveness or anaphylaxis onset. Instead, it increased tissue expression of endothelial nitric oxide synthase (eNOS). Blockage of NOS activity with the inhibitor L-NG-nitroarginine methyl ester or genetic eNOS deficiency abolished the sex-related differences.

CONCLUSION

Our study defines a contribution of estrogen through its regulation of eNOS expression and nitric oxide production to vascular hyperpermeability and intensified anaphylactic responses in female mice, providing additional mechanistic insights into risk factors and possible implications for clinical management in the further exploration of human anaphylaxis.

Pattern of Tuber melanosporum extramatrical mycelium expansion over a 20-year chronosequence in Quercus ilex-truffle orchards

Successful cultivation of black truffle (Tuber melanosporum) requires a long-term investment and the maintenance of the symbiosis throughout its preproductive and productive years. Monitoring the symbiosis over time is challenging, as it requires methods that can detect the belowground proliferation of the fungus associated with its host tree. In this study, we used a chronosequence design to study the expansion pattern of this fungus as the host tree grows. We hypothesize that this expansion can be estimated by monitoring T. melanosporum DNA from soil beneath host trees of different ages (3, 5, 7, 10, 14, and 20 years old) and at different distances from the trunk of the trees (40, 100, and 200 cm). We also wished to evaluate the presences of Tuber brumale and Tuber indicum, potentially problematic truffle species, in these plantations. To detect the mycelium of T. melanosporum in these soils, we extracted DNA and performed polymerase chain reaction (PCR) with Tuber species-specific primers, and to estimate DNA amount, we measured relative band intensities from the amplicons in agarose gels. Both age and distance were related to T. melanosporum DNA quantity, which was more abundant in the oldest age classes, reaching a plateau in 5-7 years. At 40 cm from the tree, there were no differences in T. melanosporum DNA amounts in orchards of different ages, but at 100 and 200 cm, younger orchards had less T. melanosporum DNA. We did not detect DNA from T. brumale or T. indicum in any of our samples.