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Distributed hydrological modelling moves into the realm of hyper-resolution modelling. This results in a plethora of scaling-related challenges that remain unsolved. To the user, in light of model result interpretation, finer-resolution output might imply an increase in understanding of the complex interplay of heterogeneity within the hydrological system. Here we investigate spatial scaling in the form of varying spatial resolution by evaluating the streamflow estimates of the distributed wflow_sbm hydrological model based on 454 basins from the large-sample CAMELS data set. Model instances are derived at three spatial resolutions, namely 3 km, 1 km, and 200 m. The results show that a finer spatial resolution does not necessarily lead to better streamflow estimates at the basin outlet. Statistical testing of the objective function distributions (Kling–Gupta efficiency (KGE) score) of the three model instances resulted in only a statistical difference between the 3 km and 200 m streamflow estimates. However, an assessment of sampling uncertainty shows high uncertainties surrounding the KGE score throughout the domain. This makes the conclusion based on the statistical testing inconclusive. The results do indicate strong locality in the differences between model instances expressed by differences in KGE scores of on average 0.22 with values larger than 0.5. The results of this study open up research paths that can investigate the changes in flux and state partitioning due to spatial scaling. This will help to further understand the challenges that need to be resolved for hyper-resolution hydrological modelling.

Background Although most newly presenting patients with pulmonary hypertension ( PH ) have elevated pulmonary artery wedge pressure, identification of so‐called postcapillary PH can be challenging. A noninvasive tool predicting elevated pulmonary artery wedge pressure in patients with incident PH may help avoid unnecessary invasive diagnostic procedures. Methods and Results A combination of clinical data, ECG, and echocardiographic parameters was used to refine a previously developed left heart failure risk score in a retrospective cohort of pre‐ and postcapillary PH patients. This updated score (renamed the OPTICS risk score) was externally validated in a prospective cohort of patients from 12 Dutch nonreferral centers the OPTICS network. Using the updated OPTICS risk score, the presence of postcapillary PH could be predicted on the basis of body mass index ≥30, diabetes mellitus, atrial fibrillation, dyslipidemia, history of valvular surgery, sum of SV 1 (deflection in V1 in millimeters) and RV 6 (deflection in V6 in millimeters) on ECG, and left atrial dilation. The external validation cohort included 81 postcapillary PH patients and 66 precapillary PH patients. Using a predefined cutoff of >104, the OPTICS score had 100% specificity for postcapillary PH (sensitivity, 22%). In addition, we investigated whether a high probability of heart failure with preserved ejection fraction, assessed by the H 2 FPEF score (obesity, atrial fibrillation, age >60 yrs, ≥2 antihypertensives, E/e' >9, and pulmonary artery systolic pressure by echo >35 mmHg), similarly predicted the presence of elevated pulmonary artery wedge pressure. High probability of heart failure with preserved ejection fraction (H 2 FPEF score ≥6) was less specific for postcapillary PH . Conclusions In a community setting, the OPTICS risk score can predict elevated pulmonary artery wedge pressure in PH patients without clear signs of left‐sided heart disease. The OPTICS risk score may be used to tailor the decision to perform invasive diagnostic testing.

Background: Though internet based cognitive behaviour therapy is proven to be effective, e-health is applied only in a minority of treatments in specialised mental health care. The low application rates are associated with therapists’ attitudes towards e-health. One of the major concerns is limitations in the therapeutic relation and communication between patient and therapist. Since therapist involvement is important in an effective e-health treatment, negative attitudes towards e-health can be a risk for effective e-health application. Aims:This study aimed to examine the relationship between patients’ e-health usage as well as patients’ attitudes towards e-health and the therapeutic alliance. The possible influence of therapists’ attitudes on patients’ e-health usage is also examined. Method:In an outpatient mental health setting, patients attended a blended treatment program for major depressive disorder and completed questionnaires on attitudes towards e-health and the therapeutic alliance. Therapists completed an alliance and attitude questionnaire as well. Results:Patients with more positive attitudes used the e-health application more intensively. Higher work alliance rates were related to sharing digital homework assignments and seeking contact with their therapist. Also, when treated by therapists with more positive attitudes towards e-health, patients shared more assignments with their therapist. Patients with high symptom rates at start, had more negative attitude rates and tended to use the e-health application less frequently. Conclusions:In a treatment cohesion in which therapists are positive about blended e-health, patients’ attitudes are positively related to e-health usage and therefore a factor of interest in improvement of effective e-health application. Patients with severe symptoms may need extra attention like active support and iteration to promote adherence to the e-health program.

In Huntington’s disease (HD) mutant HTT is ubiquitously expressed yet the striatum undergoes profound early degeneration. Cell culture studies suggest that a striatal-enriched protein, Rhes, may account for this vulnerability. We investigated the therapeutic potential of silencing Rhes in vivo using inhibitory RNAs (miRhes). While Rhes suppression was tolerated in wildtype mice, it failed to improve rotarod function in two distinct HD mouse models. Additionally, miRhes treated HD mice had increased anxiety-like behaviors and enhanced striatal atrophy as measured by longitudinal MRI when compared to control treated mice. These findings raise caution regarding the long-term implementation of inhibiting Rhes as a therapy for HD.

Aims: To evaluate the potential use of MALDI-TOF MS for fast and reliable classification and identification of lactic acid bacteria from traditional fermented foods. Methods and results: A total of 119 strains of LAB from fermented meat (nem chua) were analyzed with both (GTG)5-PCR fingerprinting and MALDI-TOF MS. Cluster analysis of the profiles revealed five species represented by a single isolate both in (GTG)5-PCR and in MALDI-TOF MS; five species grouped alike for (GTG)5-PCR and for MALDI-TOF MS, however, differences in minimal similarity between the delineated (GTG)5-PCR and MALDI-TOF MS clusters could be observed; three species showed more heterogeneity in their MALDI-TOF MS profiles compared to their (GTG)5-PCR profiles; two species, each represented by a single MALDI-TOF cluster were subdivided in the corresponding (GTG)5-PCR dendrogram. As proof of the identification potential of MALDI-TOF MS, LAB diversity from one fermented mustard sample was analyzed using MALDI- TOF MS. PheS gene sequencing was used for validation. Conclusions: MALDI-TOF MS is a powerful, fast, reliable, and cost effective technique for the identification of lactic acid bacteria (LAB) associated with the production of fermented foods. Significance and Impact of the Study: Food LAB can be identified using MALDI-TOF MS and its application could possibly be extended to other food matrices and/or other food derived micro-organisms.

The refinery wastewater reuse system of Sinopec Yanshan Plant in Beijing (China) has been in operation for more than four years. The water reuse system combines biological treatment, media filtration with a combination of ultrafiltration (UF) and reverse osmosis (RO). After more than 30?times of chemical cleaning, the current RO system salt rejection is still above 97% at 80% system recovery. The normalized permeate flow of the three RO trains vary with the operation time but after chemical cleaning, they recover to above the design flow of 100 m3/h. The data presented in this study indicate the fouling nature of the RO feed water on the 1st stage RO. However, according to the experience of Sinopec Yanshan Plant the output water quality meets the customer requirements. This is one of the first publications which show that the combination of UF and RO technology can be applied to reuse the refinery wastewater. The TOC rejection of the UF process is determined at 34%, which is highly dependent on the molecu...

Drugs of abuse are important emerging contaminants due to their presence in water bodies following incomplete removal in wastewater treatment. This poses a threat to drinking water sources and has led to concerns about possible health effects, both to wildlife, ecosystems and humans. In recent years, there has been growing interest in the incorporation of reverse osmosis (RO) and nanofiltration (NF) membrane technologies into existing municipal and industrial wastewater treatment facilities as a quaternary treatment option. By improving effectiveness of wastewater treatment, the exposure of firstly, nature and secondly, humans to these compounds can be minimized. It has been suggested that these membrane techniques are suitable for cost-effective desalination and the removal of a wide range of low-molecular-weight (LMW) trace organic constituents, including drugs of abuse. This paper presents the detailed results of a feasibility assessment study on the removal of selected drugs and metabolites from secon...

The DECO water treatment facility (built and operated by Evides Industriewater B.V.) is using an integrated membrane system to produce demineralised water for the production facilities of Dow Benelux B.V in Terneuzen, the Netherlands. The system consists of large-scale continuous microfiltration (CMF) unit and two-pass reverse osmosis (RO) unit with FILMTECTM membranes. It is the fi rst time in the Netherlands that domestic waste water is re-used in such a large scale for industrial use. This is an excellent example of a full scale process which was adjusted to preserve scarce fresh water resources in the region. The main goal—to minimize the environmental impact and to maximize water recovery through water recycling loops, thereby supporting the chemical industry movement to improve sustainability. This paper discusses the operational experience of the first 18 months operation with wastewater. The plant was started in 2000 and was originally designed to desalinate estuary water, due the lack of fresh wa...

We demonstrated that a yeast deletion mutant in IPT1 and SKN1, encoding proteins involved in the biosynthesis of mannosyldiinositolphosphoryl ceramides, is characterized by increased autophagy and DNA fragmentation upon nitrogen (N) starvation as compared with the single deletion mutants or wild type (WT). Apoptotic features were not significantly different between single and double deletion mutants upon N starvation, pointing to increased autophagy in the double Deltaipt1 Deltaskn1 deletion mutant independent of apoptosis. We observed increased basal levels of phytosphingosine in membranes of the double Deltaipt1 Deltaskn1 deletion mutant as compared with the single deletion mutants or WT. These data point to a negative regulation of autophagy by both Ipt1 and Skn1 in yeast, with a putative involvement of phytosphingosine in this process.

Saccharomyces cerevisiae dihydroceramidase Ydc1p hydrolyzes ceramide, resulting in accumulation of free long-chain bases and their phosphates. Yeast mutants lacking YDC1 are characterized by increased chronological lifespan. Moreover, we found YDC1 up-regulated in a yeast mutant displaying reduced chronological lifespan. These data suggest an important role for Ydc1p in chronological lifespan determination in yeast. Mitochondria are known to play an important role in chronological lifespan and apoptosis. In this study we demonstrated that overexpression of YDC1 results in reduced chronological lifespan and increased apoptotic cell death. We found YDC1 overexpression to result in mitochondrial fragmentation and dysfunction. Interestingly, vacuoles also appeared to be fragmented and dysfunctional upon YDC1 overexpressing. Exogenous addition of ceramide to YDC1-overexpressing cultures increased chronological lifespan and restored organelle function. In conclusion, this study describes a direct link between ceramide metabolism in yeast and mitochondrial and vacuolar fragmentation and function, with consequences for chronological lifespan in yeast.

Defensins are small (~5 kDa), basic, cysteine-rich antimicrobial peptides that fulfill an important role in the innate immunity of their host by combating pathogenic invading micro-organisms. Defensins can inhibit the growth or virulence of microorganisms directly or can do so indirectly by enhancing the host's immune system. Because of their wide distribution in nature, defensins are believed to be ancient molecules with a common ancestor that arose more than a billion years ago. This review summarizes current knowledge concerning the mode of antifungal action of plant, insect and human defensins.

The endocrine cells (ECs) of the gastrointestinal mucosa form the largest endocrine system in the body, not only in terms of cell numbers but also in terms of the different produced substances. Data describing the association between the relative distributions of the peptide-specific ECs in relation to feeding habits can be useful tools that enable the creation of a general expected pattern of EC distribution. We aimed to investigate the distribution of ECs immunoreactive for the peptides gastrin (GAS), cholecystokinin (CCK-8), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) in different segments of the digestive tract of carnivorous fish dorado (Salminus brasiliensis) by using immunohistochemistry procedures. The distribution of endocrine cells immunoreactive for gastrin (GAS), cholecystokinin (CCK-8), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) in digestive tract of dorado S. brasiliensis was examined by immunohistochemistry. The results describe the association between the distribution of the peptide-specific endocrine cells and feeding habits in different carnivorous fish. The largest number of endocrine cells immunoreactive for GAS, CCK-8, and CGRP were found in the pyloric stomach region and the pyloric caeca. However, NPY-immunoreactive endocrine cells were markedly restricted to the midgut. The distribution pattern of endocrine cells identified in S. brasiliensis is similar to that found in other carnivorous fishes. Fil: Pereira, R. T.. Universidade Federal de Lavras; Brasil Fil: Costa, L. S.. Universidade Federal de Lavras; Brasil Fil: Oliveira, I. R. C.. Universidade Do Sao Paulo. Escola Sup D/agricultura Luiz de Queiroz Esalq; Brasil. Hasselt University; Bélgica Fil: Araújo, J. C.. EMBRAPA Amapá; Brasil Fil: Aerts, M.. Hasselt University; Bélgica Fil: Vigliano, Fabricio Andrés. Universidad Nacional de Rosario. Facultad de Ciencias Veterinarias. Departamento de Ciencias Básicas. Cátedra de Histología y Embriología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rosa, P. V.. Universidade Federal de Lavras; Brasil

Estimating stellar parameters from spectrophotometric data is a key tool in the study of stellar structure and stellar evolution. Although many methods have been proposed to estimate stellar parameters from ultraviolet (UV), optical and infrared (IR) data using low, medium or high-resolution observational data of the target(s), only a few address the problem of the uncertainties in the stellar parameters. This information is critical for a meaningful comparison of the derived parameters with results obtained from other data and/or methods. Here we present a frequentist method to estimate these uncertainties. We demonstrate that the combined use of both a local and a global goodness-of-fit parameter alters the uncertainty intervals as determined from the use of only one of these deviation estimating parameters. This technique using both goodness-of-fit parameters is applied to the infrared 2.38-4.08 μ m ISO-SWS data (Infrared Space Observatory – Short Wavelength Spectrometer) of α Boo, yielding an effective temperature range from 4160 K to 4300 K, a logarithm of the gravity range from 1.35 to 1.65 dex and a metallicity from -0.30 to 0.00 dex. However, using a lack-of-fit test, it is shown that even the “best” theoretical models are still not capable of capturing all the structure in the data, and this is due to our incomplete knowledge and modelling of the full physical stellar structure or due to problems in the data reduction process.

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal smooth muscle neoplasms that can arise anywhere within the gastrointestinal tract. Approximately 60-70% are located in the stomach. Once considered variants of smooth muscle tumors, they are now understood as originating from the interstitial cells of Cajal or their stem cell precursors. The majority of GISTs (approximately 95%) express the CD117 antigen (KIT), a proto-oncogene product ; 85-95% of these neoplasms have mutations in the c-KIT gene; only 5-7% has mutations in platelet-derived-growth factor a (PDGFRa). GISTs can be asymptomatic and incidentally found during examination for other pathologies or at autopsy. The most common symptoms of gastric GIST are abdominal pain and bleeding. Diagnostic work up consists of endoscopy with ultrasonography and cross-sectional imaging studies (computed tomography and/or magnetic resonance imaging). Surgery remains the first-line treatment for localized gastric GISTs. Both open and laparoscopic operations have been shown to reduce recurrence rates and improve long-term survival. The use of small-molecule selective tyrosine kinase receptor inhibitors has revolutionized the treatment of advanced GISTs.

Orofacial clefts are among the commonest birth defects. Among many genetic contributors to orofacial clefting, Interferon Regulatory Factor 6 (IRF6) is unique since mutations in this gene cause Van der Woude (VWS), the most common clefting syndrome. Furthermore, variants in IRF6 contribute to increased risk for non-syndromic cleft lip and/or palate (NSCL/P). Our previous work shows that individuals with either VWS or NSCL/P may have cerebral anomalies (larger anterior, smaller posterior regions), and a smaller cerebellum. The objective of this study was to test the hypothesis that disrupting Irf6 in the mouse will result in quantitative brain changes similar to those reported for humans with VWS and NSCL/P. Male mice heterozygous for Irf6 (Irf6(gt1/+); n = 9) and wild-type (Irf6(+/+) ; n = 6) mice at comparable age underwent a 4.7-T MRI scan to obtain quantitative measures of cortical and subcortical brain structures. There was no difference in total brain volume between groups. However, the frontal cortex was enlarged in the Irf6(gt1/+) mice compared to that of wild types (P = 0.028) while the posterior cortex did not differ. In addition, the volume of the cerebellum of Irf6(gt1/+) mice was decreased (P = 0.004). Mice that were heterozygous for Irf6 showed a similar pattern of brain anomalies previously reported in humans with VWS and NSCL/P. These structural differences were present in the absence of overt oral clefts. These results support a role for IRF6 in brain morphometry and provide evidence for a potential genetic link to abnormal brain development in orofacial clefting.

Individuals with isolated cleft lip and/or palate (ICLP) are often reported to be of shorter stature relative to peers, and the objective of this study was to explore the role of the pituitary in relationship to growth.Fifty-five males and 32 females with ICLP were compared to 121 healthy males and 158 healthy females with respect to height and BMI. Magnetic resonance imaging (MRI) scans were obtained from all ICLP participants and 47% of healthy group participants.Males with ICLP were shorter than healthy males and had lower BMI. However, the trajectories for height and BMI did not differ between groups. Analyses in a separate sample of adult males suggested that height normalizes in males with ICLP in their early 30s. There were no differences in mean pituitary volume and pituitary trajectories between male groups. Females with ICLP were shorter than healthy females and also had slower growth rates. They did not differ in mean BMI or BMI trajectories. Furthermore, there were no differences in mean pituitary volume, or in pituitary trajectories.Our findings suggest that there are no gross morphological differences in pituitary volume in individuals with ICLP, although more subtle differences may exist.

The matured technology of electronic noses and tongues makes it promising to utilize the technique of combining chemically diverse sensor multi-arrays with multi-component analysis tools and pattern recognition techniques for a wider range of medical and environmental applications. With a selfdesigned sensor system and flow cell setup-up we studied the capacitive response of a polydimethyl siloxane (PDMS) covered interdigitated electrode (IDE) sensor upon exposure to methyl tert-butyl ether (MtBE) contaminated MilliQ water and plain mineral water. The sensor responded to MtBE concentrations as low as 2 ppm for both aqueous solutions with full reversibility. Signal drifts due to temperature effects can be remedied by sensor calibration. State-of-the-art sensor interfaces, system minimization and integration, and smart sensing layer design promise further significant optimization possibilities for system sensitivity, stability and response time.

Hantaviruses were first described in Korea in 1978, and are an important group of “new” pathogens, now constituting the most widely distributed zoonotic (i.e. transmitted from vertebrated animals to humans) viruses on earth. Hantaviruses are “emerging” viruses, and are now confirmed as being the only viral haemorrhagic fever agents with a worldwide distribution, including even the temperate Northern hemisphere (Clement et al. 2007a). They are spread by wild rodents (and perhaps also by insectivores), infecting man via their aerosolized but infectious excreta. So far, at least 23 different hantavirus species are officially recognized, each with its own main rodent reservoir, and hence specific geographical spread (Maes et al, 2009). The most important pathogens are Hantaan and Seoul virus in Asia, Puumala and Dobrava virus in Europe and West-Russia, and Sin Nombre and Andes virus in the Americas. American hantaviruses, discovered only in 1993, affect mainly the human lung and cause the “hantavirus cardiopulmonary syndrome” (HCPS), with a fatality rate of about 35%. By contrast, all Old World hantaviruses are targeted mainly to the human kidney resulting in the “haemorrhagic fever with renal syndrome” (HFRS), an often epidemic form of acute kidney injury (AKI), resulting in a rapidly progressive, but ultimately self-remitting acute renal failure (Clement et al., 2007a, 2007b). Among hantaviral pathogens, the European Puumala virus (PUUV) is the least severe. It causes an infection, aptly named “nephropathia epidemica” (NE), which in fact is a mild form of HFRS, with a very low fatality rate of 0.5-0.1 %. However, more severe cases do occur, resulting in multiorgan involvement, necessitating sometimes live-saving acute haemodialysis and/or mechanical lung ventilation in intensive care settings (Clement et al., 1994a, 2007a, 2007b).

Plant defensins are active against plant and human pathogenic fungi (such as Candida albicans) and baker's yeast. However, they are non-toxic to human cells, providing a possible source for treatment of fungal infections. In this study, we characterized the mode of action of the antifungal plant defensin HsAFP1 from coral bells by screening the Saccharomyces cerevisiae deletion mutant library for mutants with altered HsAFP1 sensitivity and verified the obtained genetic data by biochemical assays in S. cerevisiae and C. albicans. We identified 84 genes, which when deleted conferred at least fourfold hypersensitivity or resistance to HsAFP1. A considerable part of these genes were found to be implicated in mitochondrial functionality. In line, sodium azide, which blocks the respiratory electron transport chain, antagonized HsAFP1 antifungal activity, suggesting that a functional respiratory chain is indispensable for HsAFP1 antifungal action. Since mitochondria are the main source of cellular reactive oxygen species (ROS), we investigated the ROS-inducing nature of HsAFP1. We showed that HsAFP1 treatment of C. albicans resulted in ROS accumulation. As ROS accumulation is one of the phenotypic markers of apoptosis in yeast, we could further demonstrate that HsAFP1 induced apoptosis in C. albicans. These data provide novel mechanistic insights in the mode of action of a plant defensin.

A 33-year-old man presented with recurrent episodes of hyperemesis with symptom-free intervals since eight years. The diagnosis of cyclic vomiting syndrome due to longstanding and daily cannabis use was retained, after exclusion of any organic cause of vomiting. Although the patient was informed that the clinical response after cessation of smoking is proven to be spectacular, he continued the use of cannabis and kept on presenting with cyclic symptoms of hyperemesis.

Gaucher disease type I, the most common lysosomal storage disorder, is associated with immunoglobulin abnormalities. We studied the prevalence, risk factors, pathogenesis, and effect of enzyme relation therapy (ERT) on gammopathies in an adult Gaucher disease type I cohort (N = 63) and related the results to a review of the currently available literature. Polyclonal gammopathies and monoclonal gammopathy of undetermined significance (MGUS) in our adult GD I cohort were found in 41% and 19% of patients. These results are similar to the data from the literature and correspond to the increased risk of multiple myeloma (MM) that has been described. The prevalence of MGUS in our cohort increased with age but was not associated with disease severity or exposure time. The serum levels of free light chains of immunoglobulins were measured and were not found predictive for the development of MGUS or MM. Levels of pro- as well as anti-inflammatory cytokines, growth factors, and chemokines, especially those involved in inflammation and B-cell function, are disturbed in GD I, with the most impressive and consisting elevations for interleukin-10 and pulmonary and activation-regulated chemokine. A beneficial effect of ERT on the occurrence and progression of gammopathies was suggested from longitudinal data.

The antifungal compound miconazole inhibits ergosterol biosynthesis and induces reactive oxygen species (ROS) in susceptible yeast species. To further uncover the mechanism of miconazole antifungal action and tolerance mechanisms, we screened the complete set of haploid Saccharomyces cerevisiae gene deletion mutants for mutants with an altered miconazole sensitivity phenotype. We identified 29 S. cerevisiae genes, which when deleted conferred at least 4-fold hypersensitivity to miconazole. Major functional groups encode proteins involved in tryptophan biosynthesis, membrane trafficking including endocytosis, regulation of actin cytoskeleton, and gene expression. With respect to the antifungal activity of miconazole, we demonstrate an antagonism with tryptophan and a synergy with a yeast endocytosis inhibitor. Because actin dynamics and induction of ROS are linked in yeast, we further focused on miconazole-mediated changes in actin cytoskeleton organization. In this respect, we demonstrate that miconazole induces changes in the actin cytoskeleton, indicative of increased filament stability, prior to ROS induction. These data provide novel mechanistic insights in the mode of action of a ROS-inducing azole.

In an earlier study published in this journal (Berger e.a. 2002) it was shown that the cognitive styles 'weak central coherence' and 'poor cognitive shifting' are common in autism spectrum disorders, but tests have revealed that the styles do not apply to every member of the patient group. This finding could have consequences for the course of treatment.To find out if the cognitive styles of autistic patients can predict whether their social functioning will improve after three years of treatment we conducted a follow-up study in which we examined 44 non-retarded adolescents with an autism spectrum disorder who were receiving residential treatment.On the basis of factor scores awarded in an extensive battery of neuropsychological tests, we formed subgroups of patients with weak versus strong central coherence and cognitive shifting. Then analyses of variance were used to discover whether the subgroups were predictors of changes in three aspects of social functioning: autistic symptoms, social intelligence and social competence.We found a small but significant gain in all the social domains. However, there were clear individual differences in the degree of improvement. Cognitive shifting was found to be a predictor of a clinically meaningful improvement in social competence.The correlation found between cognitive shifting and social competence indicates that patients with an autism spectrum disorder should be given different forms of treatment that take differences in cognitive style into account.

The antifungal plant defensin DmAMP1 interacts with fungal sphingolipids of mannosyldiinositolphosphorylceramide (M(IP)2C) class. We screened a Saccharomyces cerevisiae transposon (Tn) mutant library against DmAMP1 and identified one DmAMP1-resistant mutant with the Tn inserted in the M(IP)2C biosynthesis gene IPT1 (DmTn11) and one DmAMP1-hypersensitive mutant with the Tn inserted in rDNA (HsTnII). However, tetrad analysis pointed to HsTnII as a spontaneous mutant. Apparently, membranes of DmTn11 lack M(IP)2C, whereas membranes of HsTnII have increased M(IP)2C levels. In addition, DmTn11 and HsTnII are characterized by increased and reduced oxidative stress resistance/chronological life-span (CL), respectively. A putative involvement of M(IP)2C in oxidative stress and CL in yeast is discussed.

The antifungal plant defensin DmAMP1 interacts with the fungal sphingolipid mannosyl diinositolphosphoryl ceramide (M(IP)(2)C) and induces fungal growth inhibition. We have identified SKN1, besides the M(IP)(2)C-biosynthesis gene IPT1, as a novel DmAMP1-sensitivity gene in Saccharomyces cerevisiae. SKN1 was previously shown to be a KRE6 homologue, which is involved in beta-1,6-glucan biosynthesis. We demonstrate that a Deltaskn1 mutant lacks M(IP)(2)C. Interestingly, overexpression of either IPT1 or SKN1 complemented the skn1 mutation, conferred sensitivity to DmAMP1, and resulted in M(IP)(2)C levels comparable to the wild type. These results show that SKN1, together with IPT1, is involved in sphingolipid biosynthesis in S. cerevisiae.