Association of High-Sensitivity Troponin I with Cardiac and Cerebrovascular Events in Patient after Ischemic Stroke.

INTRODUCTION: Early recognition and risk stratification of cardiovascular events are necessary in patients after ischemic stroke. Recent evidence suggests that elevated high-sensitive cardiac troponin is a predictor of mortality and vascular events. Therefore, we aimed to explore the prognostic role of high-sensitive cardiac troponin I (hs-TnI) on mortality and cardiovascular outcomes in patients after ischemic stroke. METHODS: From August 2014 to July 2017, 1,506 patients with acute ischemic stroke were pulled consecutively in a retrospective single-center registry. Of these, 1,019 patients were selected and classified into the elevated or non-elevated hs-TnI groups according to hs-TnI level of 99th percentile upper reference limit (URL) at the time of admission for ischemic stroke. The primary outcome was a major adverse cardiac and cerebrovascular event (MACCE) during follow-up. RESULTS: Among 1,019 patients, 708 patients were non-elevated hs-TnI group (<99th percentile URL of hs-TnI) and 311 patients were elevated hs-TnI group (≥99th percentile URL of hs-TnI). The median follow-up period was 22.5 (interquartile range 5.0-38.8) months. In a multivariable Cox regression model, the elevated hs-TnI group has a higher risk of MACCE (adjusted hazard ratio [HR]: 3.12; 95% confidence interval [CI]: 2.33-4.17; p < 0.01), all-cause mortality (adjusted HR: 4.15; 95% CI: 2.47-6.99; p < 0.01) and readmission caused by coronary revascularization (adjusted HR: 3.12; 95% CI: 1.41-6.90; p < 0.01), heart failure (adjusted HR: 2.76; 95% CI: 1.38-5.51; p < 0.01), and stroke (adjusted HR: 1.73; 95% CI: 1.07-2.78; p = 0.02) compared with the non-elevated hs-TnI group. CONCLUSIONS: Elevated hs-TnI is independently associated with higher mortality and cardiac and cerebrovascular events in patients with ischemic stroke and may serve as a valuable prognostic factor in management after ischemic stroke.

Low-Molecular-Weight Fish Collagen Peptide (Valine-Glycine-Proline-Hydroxyproline-Glycine-Proline-Alanine-Glycine) Prevents Osteoarthritis Symptoms in Chondrocytes and Monoiodoacetate-Injected Rats.

The objective of this study was to investigate the effect of low-molecular-weight fish collagen (valine-glycine-proline-hydroxyproline-glycine-proline-alanine-glycine; LMWCP) on H2O2- or LPS-treated primary chondrocytes and monoiodoacetate (MIA)-induced osteoarthritis rat models. Our findings indicated that LMWCP treatment exhibited protective effects by preventing chondrocyte death and reducing matrix degradation in both H2O2-treated primary chondrocytes and cartilage tissue from MIA-induced osteoarthritis rats. This was achieved by increasing the levels of aggrecan, collagen type I, collagen type II, TIMP-1, and TIMP-3, while simultaneously decreasing catabolic factors such as phosphorylation of Smad, MMP-3, and MMP-13. Additionally, LMWCP treatment effectively suppressed the activation of inflammation and apoptosis pathways in both LPS-treated primary chondrocytes and cartilage tissue from MIA-induced osteoarthritis rats. These results suggest that LMWCP supplementation ameliorates the progression of osteoarthritis through its direct impact on inflammation and apoptosis in chondrocytes.

Enzyme-Treated Caviar Prevents UVB Irradiation-Induced Skin Photoaging.

For this research article, we investigated the protective effects of enzyme-treated caviar powder extract (CV) in ultraviolet B (UVB)-irradiated hairless mice and keratinocytes by confirming moisturizing-related factors and elasticity-related factors. UVB irradiation induced wrinkle formation, dehydration, oxidative stress, and inflammation in the dorsal skin of mice; however, these were suppressed in the CV-supplemented groups in UVB-irradiated hairless mice. Furthermore, in UVB-irradiated keratinocytes, CV treatment increased the antioxidant enzyme activities and the levels of sphingomyelin and hyaluronic acid and decreased the production of pro-inflammatory cytokines and the expression of IkB-α and p65 phosphorylation. These findings indicate that CV can directly protect keratinocytes against UVB irradiation-induced oxidative stress and inflammation. Therefore, we suggest that CV can protect against UVB-induced skin photoaging. Therefore, we suggest that caviar is effective for skin health by preventing UVB-induced skin photoaging.

Association between diabetes mellitus and chronic rhinosinusitis with nasal polyps: A population-based cross-sectional study.

OBJECTIVE: To investigate the association between physician-diagnosed diabetes mellitus (DM) and chronic rhinosinusitis (CRS) phenotypes in a national population-based study. STUDY DESIGN: Retrospective cross-sectional study. SETTING: Population-based survey data were collected by the Korean National Health and Nutrition Survey between January 2008 and December 2012. PARTICIPANTS AND METHODS: A total of 34 670 participants aged over 19 years were enrolled in the Korea National Health and Nutrition Examination Surveys from 2008 to 2012. The relationship of CRS prevalence, with and without nasal polyps, with physician-diagnosed DM and non-DM were assessed. Differences in sinonasal symptoms between patients with and without DM were analysed in this cross-sectional study. RESULTS: A significant association was observed between DM and CRS with nasal polyps after adjustment for multiple variables. No substantial association was observed between DM and CRS without nasal polyps. Among patients with CRS, olfactory dysfunction for >3 months was significantly more frequent in the DM group than in the non-DM group. CONCLUSION: We demonstrated significant associations between DM and CRS with nasal polyps and olfactory dysfunction among patients with CRS in a large national clinical cohort study. The direct mechanism of the association between DM and CRS with nasal polyps should be further investigated to clarify the pathogenesis of CRS with nasal polyps.

Changing Susceptibility of Staphylococci in Patients with Implant-Based Breast Reconstructions: A Single-Center Experience.

Background and Objectives: Infections and capsular contractures remain unresolved issues in implant-based breast reconstruction. Capsular contractures are thought to be caused by the endogenous flora of the nipple duct. However, little is known about the antibiotic susceptibility of the microorganisms involved. This study aimed to evaluate the composition of endogenous breast flora and its antimicrobial susceptibility in patients with breast cancer. This study will aid in selecting a prophylactic antibiotic regimen for breast reconstruction surgery. Materials and Methods: We obtained bacteriologic swabs from the nipple intraoperatively in patients who underwent implant-based breast reconstruction following nipple-sparing mastectomy between January 2019 and August 2021. Antibiotic susceptibility tests were performed according to the isolated bacteriology. Statistical analysis was performed based on several patient variables to identify which factors influence the antibiotic resistance rate of endogenous flora. Results: A total of 125 of 220 patients had positive results, of which 106 had positive culture results for coagulase-negative Staphylococcus species (CoNS). Among these 106 patients, 50 (47%) were found to have methicillin-resistant staphylococci, and 56 (53%) were found to have methicillin-susceptible staphylococci. The methicillin resistance rate in the neoadjuvant chemotherapy group (56.3%) was significantly higher (OR, 2.3; p = 0.039) than that in the non-neoadjuvant chemotherapy group (35.5%). Conclusions: Based on the results, demonstrating high and rising incidence of methicillin-resistant staphylococci of nipple endogenous flora in patients with breast cancer compared to the past, it is necessary to consider the selection of prophylactic antibiotics to reduce infections and capsular contracture after implant-based breast reconstruction.

Migraine with Aura as a Stroke Mimic.

Migraine with aura is one of the causes of stroke mimics. We retrospectively reviewed the 10-year medical records of patients who were treated with acute stroke management protocol. We analyzed the frequency and characteristics of patients with a final diagnosis of migraine with aura. Among the 1355 patients with stroke mimics, migraine with aura was the final diagnosis in 36 patients (2.7%). The most common auras included sensory and brainstem auras followed by motor, visual, and speech/language auras. One patient manifested transient atrial fibrillation during the migraine attack, which can be a link with acute stroke.

Seizure in code stroke: Stroke mimic and initial manifestation of stroke.

BACKGROUND: Although seizure is one of the common causes of stroke mimics and can be an initial manifestation of acute stroke, accurate diagnosis of seizure during acute stroke management is frequently difficult. The objective of this study was to analyze the frequency, characteristics and results of neuroimaging including CT perfusion in patients with seizures manifesting initially as stroke-like symptoms. METHODS: We retrospectively reviewed the medical records of patients who were treated with code stroke alarming system. We studied the frequency and characteristics of patients who were finally diagnosed with seizures and further correlated their clinical features with the results of neuroimaging including CT perfusion. RESULTS: Among the 4673 patients who were treated with code stroke alarming system, seizure was the third most frequent diagnosis (188 patients, 4.0%) among the causes of stroke mimics including 27 patients who manifested seizure as an initial manifestation of acute stroke. CT perfusion showed perfusion changes in more than 25% of them (49 of 188 patients, 26.1%). Thrombolysis was not performed in six patients who presented with seizure as an initial presentation of stroke for delayed diagnosis while one patient underwent thrombolysis for misdiagnosis of seizure. CONCLUSIONS: Seizure is a frequent final diagnosis in acute stroke management. However, careful interpretation of clinical features and results of perfusion imaging is necessary to avoid unnecessary thrombolysis in patients with seizure as a stroke mimic and thrombolysis failure due to delayed diagnosis of seizure as an initial manifestation of stroke.

Costaria costata Extract Suppresses Development of Atopic Dermatitis in chloro-2,4-dinitrobenzene-treated NC/Nga Mice.

We investigated the potential effects of Costaria costata (CC) on atopic dermatitis (AD) development in chloro-2,4-dinitrobenzene (DNCB)-treated NC/Nga mice. CC is a brown alga distributed across the seas of Korea, China, and Japan. A total of 40 mice were randomly assigned to 5 groups with 8 mice per group: untreated Balb/c mice, AD control (0.1% w/v DNCB-treated NC/Nga mice), positive control (i.e., DNCB-treated NC/Nga mice fed a dietary supplement of 66.6 mg/kg of body weight [b.w.] of CJLP133), DNCB-treated NC/Nga mice fed a dietary supplement of 100 mg/kg b.w. of CCE10 (CCE10 100), and DNCB-treated mice fed a dietary supplement of 300 mg/kg b.w. of CCE10 (CCE10 300) groups. The CCE10 100 and CCE10 300 treatment groups suppressed AD development including clinical and histopathological changes and a reduction in skin hydration induced by DNCB. In addition, Th2 cytokine production in primary splenocytes, serum IgE and histamine production, and mast cell infiltration into the skin were suppressed in the CCE10 300 mice compared to the CCE10 100 mice. Our finding demonstrated an inhibitory effect of CCE10 in AD development by means of improving the Th1/Th2 cytokine balance and anti-inflammatory effect in an in vivo model.

Production of the antibiotic secondary metabolite solanapyrone A by the fungal plant pathogen Ascochyta rabiei during fruiting body formation in saprobic growth.

Fungi are noted producers of a diverse array of secondary metabolites, many of which are of pharmacological importance. However, the biological roles of the vast majority of these molecules during the fungal life cycle in nature remain elusive. Solanapyrones are polyketide-derived secondary metabolites produced by diverse fungal species including the plant pathogen Ascochyta rabiei. This molecule was originally thought to function as a phytotoxin facilitating pathogenesis of A. rabiei. Chemical profiling and gene expression studies showed that solanapyrone A was specifically produced during saprobic, but not parasitic growth of A. rabiei. Expression of the gene encoding the final enzymatic step in solanapyrone biosynthesis was specifically associated with development of the asexual fruiting bodies of the fungus on certain substrates. In confrontation assays with saprobic fungi that were commonly found in chickpea debris in fields, A. rabiei effectively suppressed the growth of all competing fungi, such as Alternaria, Epicoccum and Ulocladium species. Solanapyrone A was directly detected in the inhibitory zone using a MALDI-imaging mass spectrometry, and the purified compound showed significant antifungal activities against the potential saprobic competitors. These results suggest that solanapyrone A plays an important role for competition and presumably the survival of the fungus.

Impaired Tilt Suppression of Post-Rotatory Nystagmus and Cross-Coupled Head-Shaking Nystagmus in Cerebellar Lesions: Image Mapping Study.

We sought to determine the cerebellar structures responsible for tilt suppression of post-rotatory nystagmus. We investigated ocular motor findings and MRI lesions in 73 patients with isolated cerebellar lesions who underwent recording of the vestibulo-ocular reflex (VOR) using rotatory chair tests. Tilt suppression of post-rotatory nystagmus was diminished in 27 patients (27/73, 37.0 %). The gains of the VOR and the TCs of per- and post-rotatory nystagmus did not differ between the patients with diminished and with normal tilt suppression. The patients with impaired tilt suppression showed perverted ("cross-coupled") head-shaking nystagmus (pHSN) and central positional nystagmus (CPN) more frequently than those with normal responses. Tilt suppression was impaired in five (71.4 %) of the seven patients with isolated nodulus and uvular infarction. Probabilistic lesion-mapping analysis showed that the nodulus and uvula are responsible for tilt suppression. Impaired tilt suppression may be ascribed to disruption of cerebellar contribution to the vestibular velocity-storage mechanism, which integrates information from the semicircular canals and otolith organs to help derive the brain's estimate of the head orientation relative to the pull of gravity.

Fecal Metabolome in Hmga1 Transgenic Mice with Polyposis: Evidence for Potential Screen for Early Detection of Precursor Lesions in Colorectal Cancer.

Because colorectal cancer (CRC) remains a leading cause of cancer mortality worldwide, more accessible screening tests are urgently needed to identify early stage lesions. We hypothesized that highly sensitive, metabolic profile analysis of stool samples will identify metabolites associated with early stage lesions and could serve as a noninvasive screening test. We therefore applied traveling wave ion mobility mass spectrometry (TWIMMS) coupled with ultraperformance liquid chromatography (UPLC) to investigate metabolic aberrations in stool samples in a transgenic model of premalignant polyposis aberrantly expressing the gene encoding the high mobility group A (Hmga1) chromatin remodeling protein. Here, we report for the first time that the fecal metabolome of Hmga1 mice is distinct from that of control mice and includes metabolites previously identified in human CRC. Significant alterations were observed in fatty acid metabolites and metabolites associated with bile acids (hypoxanthine xanthine, taurine) in Hmga1 mice compared to controls. Surprisingly, a marked increase in the levels of distinctive short, arginine-enriched, tetra-peptide fragments was observed in the transgenic mice. Together these findings suggest that specific metabolites are associated with Hmga1-induced polyposis and abnormal proliferation in intestinal epithelium. Although further studies are needed, these data provide a compelling rationale to develop fecal metabolomic analysis as a noninvasive screening tool to detect early precursor lesions to CRC in humans.

The response of Chlamydomonas reinhardtii to nitrogen deprivation: a systems biology analysis.

Drastic alteration in macronutrients causes large changes in gene expression in the photosynthetic unicellular alga Chlamydomonas reinhardtii. Preliminary data suggested that cells follow a biphasic response to this change hinging on the initiation of lipid accumulation, and we hypothesized that drastic repatterning of metabolism also followed this biphasic modality. To test this hypothesis, transcriptomic, proteomic, and metabolite changes that occur under nitrogen (N) deprivation were analyzed. Eight sampling times were selected covering the progressive slowing of growth and induction of oil synthesis between 4 and 6 h after N deprivation. Results of the combined, systems-level investigation indicated that C. reinhardtii cells sense and respond on a large scale within 30 min to a switch to N-deprived conditions turning on a largely gluconeogenic metabolic state, which then transitions to a glycolytic stage between 4 and 6 h after N depletion. This nitrogen-sensing system is transduced to carbon- and nitrogen-responsive pathways, leading to down-regulation of carbon assimilation and chlorophyll biosynthesis, and an increase in nitrogen metabolism and lipid biosynthesis. For example, the expression of nearly all the enzymes for assimilating nitrogen from ammonium, nitrate, nitrite, urea, formamide/acetamide, purines, pyrimidines, polyamines, amino acids and proteins increased significantly. Although arginine biosynthesis enzymes were also rapidly up-regulated, arginine pool size changes and isotopic labeling results indicated no increased flux through this pathway.

The regulation of photosynthetic structure and function during nitrogen deprivation in Chlamydomonas reinhardtii.

The accumulation of carbon storage compounds by many unicellular algae after nutrient deprivation occurs despite declines in their photosynthetic apparatus. To understand the regulation and roles of photosynthesis during this potentially bioenergetically valuable process, we analyzed photosynthetic structure and function after nitrogen deprivation in the model alga Chlamydomonas reinhardtii. Transcriptomic, proteomic, metabolite, and lipid profiling and microscopic time course data were combined with multiple measures of photosynthetic function. Levels of transcripts and proteins of photosystems I and II and most antenna genes fell with differing trajectories; thylakoid membrane lipid levels decreased, while their proportions remained similar and thylakoid membrane organization appeared to be preserved. Cellular chlorophyll (Chl) content decreased more than 2-fold within 24 h, and we conclude from transcript protein and (13)C labeling rates that Chl synthesis was down-regulated both pre- and posttranslationally and that Chl levels fell because of a rapid cessation in synthesis and dilution by cellular growth rather than because of degradation. Photosynthetically driven oxygen production and the efficiency of photosystem II as well as P700(+) reduction and electrochromic shift kinetics all decreased over the time course, without evidence of substantial energy overflow. The results also indicate that linear electron flow fell approximately 15% more than cyclic flow over the first 24 h. Comparing Calvin-Benson cycle transcript and enzyme levels with changes in photosynthetic (13)CO2 incorporation rates also pointed to a coordinated multilevel down-regulation of photosynthetic fluxes during starch synthesis before the induction of high triacylglycerol accumulation rates.

A Novel Type Pathway-Specific Regulator and Dynamic Genome Environments of a Solanapyrone Biosynthesis Gene Cluster in the Fungus Ascochyta rabiei.

Secondary metabolite genes are often clustered together and situated in particular genomic regions, like the subtelomere, that can facilitate niche adaptation in fungi. Solanapyrones are toxic secondary metabolites produced by fungi occupying different ecological niches. Full-genome sequencing of the ascomycete Ascochyta rabiei revealed a solanapyrone biosynthesis gene cluster embedded in an AT-rich region proximal to a telomere end and surrounded by Tc1/Mariner-type transposable elements. The highly AT-rich environment of the solanapyrone cluster is likely the product of repeat-induced point mutations. Several secondary metabolism-related genes were found in the flanking regions of the solanapyrone cluster. Although the solanapyrone cluster appears to be resistant to repeat-induced point mutations, a P450 monooxygenase gene adjacent to the cluster has been degraded by such mutations. Among the six solanapyrone cluster genes (sol1 to sol6), sol4 encodes a novel type of Zn(II)2Cys6 zinc cluster transcription factor. Deletion of sol4 resulted in the complete loss of solanapyrone production but did not compromise growth, sporulation, or virulence. Gene expression studies with the sol4 deletion and sol4-overexpressing mutants delimited the boundaries of the solanapyrone gene cluster and revealed that sol4 is likely a specific regulator of solanapyrone biosynthesis and appears to be necessary and sufficient for induction of the solanapyrone cluster genes. Despite the dynamic surrounding genomic regions, the solanapyrone gene cluster has maintained its integrity, suggesting important roles of solanapyrones in fungal biology.

HMGA1 drives metabolic reprogramming of intestinal epithelium during hyperproliferation, polyposis, and colorectal carcinogenesis.

Although significant progress has been made in the diagnosis and treatment of colorectal cancer (CRC), it remains a leading cause of cancer death worldwide. Early identification and removal of polyps that may progress to overt CRC is the cornerstone of CRC prevention. Expression of the High Mobility Group A1 (HMGA1) gene is significantly elevated in CRCs as compared with adjacent, nonmalignant tissues. We investigated metabolic aberrations induced by HMGA1 overexpression in small intestinal and colonic epithelium using traveling wave ion mobility mass spectrometry (TWIMMS) in a transgenic model in which murine Hmga1 was misexpressed in colonic epithelium. To determine if these Hmga1-induced metabolic alterations in mice were relevant to human colorectal carcinogenesis, we also investigated tumors from patients with CRC and matched, adjacent, nonmalignant tissues. Multivariate statistical methods and manual comparisons were used to identify metabolites specific to Hmga1 and CRC. Statistical modeling of data revealed distinct metabolic patterns in Hmga1 transgenics and human CRC samples as compared with the control tissues. We discovered that 13 metabolites were specific for Hmga1 in murine intestinal epithelium and also found in human CRC. Several of these metabolites function in fatty acid metabolism and membrane composition. Although further validation is needed, our results suggest that high levels of HMGA1 protein drive metabolic alterations that contribute to CRC pathogenesis through fatty acid synthesis. These metabolites could serve as potential biomarkers or therapeutic targets.

Unexpected roles for ancient proteins: flavone 8-hydroxylase in sweet basil trichomes is a Rieske-type, PAO-family oxygenase.

Most elucidated hydroxylations in plant secondary metabolism are catalyzed by oxoglutarate- or cytochrome P450-dependent oxygenases. Numerous hydroxylations still evade clarification, suggesting that they might be performed by alternative enzyme types. Here, we report the identification of the flavone 8-hydroxylase (F8H) in sweet basil (Ocimum basilicum L.) trichomes as a Rieske-type oxygenase. Several features of the F8H activity in trichome protein extracts helped to differentiate it from a cytochrome P450-catalyzed reaction and identify candidate genes in the basil trichome EST database. The encoded ObF8H proteins share approximately 50% identity with Rieske-type protochlorophyllide a oxygenases (PTC52) from higher plants. Homology cloning and DNA blotting revealed the presence of several PTC52-like genes in the basil genome. The transcripts of the candidate gene designated ObF8H-1 are strongly enriched in trichomes compared to whole young leaves, indicating trichome-specific expression. The full-length ObF8H-1 protein possesses a predicted N-terminal transit peptide, which directs green fluorescent protein at least in part to chloroplasts. The F8H activity in crude trichome protein extracts correlates well with the abundance of ObF8H peptides. The purified recombinant ObF8H-1 displays high affinity for salvigenin and is inactive with other tested flavones except cirsimaritin, which is 8-hydroxylated with less than 0.2% relative activity. The efficiency of in vivo 8-hydroxylation by engineered yeast was improved by manipulation of protein subcellular targeting. blast searches showed that occurrence of several PTC52-like genes is rather common in sequenced plant genomes. The discovery of ObF8H suggests that Rieske-type oxygenases may represent overlooked candidate catalysts for oxygenations in specialized plant metabolism.

Staphylococcus aureus induces hypoxia and cellular damage in porcine dermal explants.

We developed a porcine dermal explant model to determine the extent to which Staphylococcus aureus biofilm communities deplete oxygen, change pH, and produce damage in underlying tissue. Microelectrode measurements demonstrated that dissolved oxygen (DO) in biofilm-free dermal tissue was 4.45 ± 1.17 mg/liter, while DO levels for biofilm-infected tissue declined sharply from the surface, with no measurable oxygen detectable in the underlying dermal tissue. Magnetic resonance imaging demonstrated that biofilm-free dermal tissue had a significantly lower relative effective diffusion coefficient (0.26 ± 0.09 to 0.30 ± 0.12) than biofilm-infected dermal tissue (0.40 ± 0.12 to 0.48 ± 0.12; P < 0.0001). Thus, the difference in DO level was attributable to biofilm-induced oxygen demand rather than changes in oxygen diffusivity. Microelectrode measures showed that pH within biofilm-infected explants was more alkaline than in biofilm-free explants (8.0 ± 0.17 versus 7.5 ± 0.15, respectively; P < 0.002). Cellular and nuclear details were lost in the infected explants, consistent with cell death. Quantitative label-free shotgun proteomics demonstrated that both proapoptotic programmed cell death protein 5 and antiapoptotic macrophage migration inhibitory factor accumulated in the infected-explant spent medium, compared with uninfected-explant spent media (1,351-fold and 58-fold, respectively), consistent with the cooccurrence of apoptosis and necrosis in the explants. Biofilm-origin proteins reflected an extracellular matrix-adapted lifestyle of S. aureus. S. aureus biofilms deplete oxygen, increase pH, and induce cell death, all factors that contribute to impede wound healing.

Colonization of epidermal tissue by Staphylococcus aureus produces localized hypoxia and stimulates secretion of antioxidant and caspase-14 proteins.

A partial-thickness epidermal explant model was colonized with green fluorescent protein (GFP)-expressing Staphylococcus aureus, and the pattern of S. aureus biofilm growth was characterized using electron and confocal laser scanning microscopy. The oxygen concentration in explants was quantified using microelectrodes. The relative effective diffusivity and porosity of the epidermis were determined using magnetic resonance imaging, while hydrogen peroxide (H2O2) concentration in explant media was measured by using microelectrodes. Secreted proteins were identified and quantified using elevated-energy mass spectrometry (MS(E)). S. aureus biofilm grows predominantly in lipid-rich areas around hair follicles and associated skin folds. Dissolved oxygen was selectively depleted (2- to 3-fold) in these locations, but the relative effective diffusivity and porosity did not change between colonized and control epidermis. Histological analysis revealed keratinocyte damage across all the layers of colonized epidermis after 4 days of culture. The colonized explants released significantly (P < 0.01) more antioxidant proteins of both epidermal and S. aureus origin, consistent with elevated H2O2 concentrations found in the media from the colonized explants (P< 0.001). Caspase-14 was also elevated significantly in the media from the colonized explants. While H2O2 induces primary keratinocyte differentiation, caspase-14 is required for terminal keratinocyte differentiation and desquamation. These results are consistent with a localized biological impact from S. aureus in response to colonization of the skin surface.

Functional Analyses of the Diels-Alderase Gene sol5 of Ascochyta rabiei and Alternaria solani Indicate that the Solanapyrone Phytotoxins Are Not Required for Pathogenicity.

Ascochyta rabiei and Alternaria solani, the causal agents of Ascochyta blight of chickpea (Cicer arietinum) and early blight of potato (Solanum tuberosum), respectively, produce a set of phytotoxic compounds including solanapyrones A, B, and C. Although both the phytotoxicity of solanapyrones and their universal production among field isolates have been documented, the role of solanapyrones in pathogenicity is not well understood. Here, we report the functional characterization of the sol5 gene, which encodes a Diels-Alderase that catalyzes the final step of solanapyrone biosynthesis. Deletion of sol5 in both Ascochyta rabiei and Alternaria solani completely prevented production of solanapyrones and led to accumulation of the immediate precursor compound, prosolanapyrone II-diol, which is not toxic to plants. Deletion of sol5 did not negatively affect growth rate or spore production in vitro, and led to overexpression of the other solanapyrone biosynthesis genes, suggesting a possible feedback regulation mechanism. Phytotoxicity tests showed that solanapyrone A is highly toxic to several legume species and Arabidopsis thaliana. Despite the apparent phytotoxicity of solanapyrone A, pathogenicity tests showed that solanapyrone-minus mutants of Ascochyta rabiei and Alternaria solani were equally virulent as their corresponding wild-type progenitors, suggesting that solanapyrones are not required for pathogenicity.

Functional Analyses of the Diels-Alderase Gene sol5 of Ascochyta rabiei and Alternaria solani Indicate that the Solanapyrone Phytotoxins Are Not Required for Pathogenicity.

Ascochyta rabiei and Alternaria solani, the causal agents of Ascochyta blight of chickpea (Cicer arietinum) and early blight of potato (Solanum tuberosum), respectively, produce a set of phytotoxic compounds including solanapyrones A, B, and C. Although both the phytotoxicity of solanapyrones and their universal production among field isolates have been documented, the role of solanapyrones in pathogenicity is not well understood. Here, we report the functional characterization of the sol5 gene, which encodes a Diels-Alderase that catalyzes the final step of solanapyrone biosynthesis. Deletion of sol5 in both Ascochyta rabiei and Alternaria solani completely prevented production of solanapyrones and led to accumulation of the immediate precursor compound, prosolanapyrone II-diol, which is not toxic to plants. Deletion of sol5 did not negatively affect growth rate or spore production in vitro, and led to overexpression of the other solanapyrone biosynthesis genes, suggesting a possible feedback regulation mechanism. Phytotoxicity tests showed that solanapyrone A is highly toxic to several legume species and Arabidopsis thaliana. Despite the apparent phytotoxicity of solanapyrone A, pathogenicity tests showed that solanapyrone-minus mutants of Ascochyta rabiei and Alternaria solani were equally virulent as their corresponding wild-type progenitors, suggesting that solanapyrones are not required for pathogenicity.