Antagonistic Responses Research Articles

Ethylene mediates salicylic-acid-induced stomatal closure by controlling reactive oxygen species and nitric oxide production in Arabidopsis

Both salicylic acid (SA) and ethylene induce stomatal closure and positively regulate stomatal immunity, but their interactions in guard cell signaling are unclear. Here, we observed that SA induced the expression of ethylene biosynthetic genes; the production of ethylene, reactive oxygen species (ROS) and nitric oxide (NO); and stomatal closure in Arabidopsis thaliana. However, SA-induced stomatal closure was inhibited by an ethylene biosynthetic inhibitor and mutations in ethylene biosynthetic genes, ethylene-signaling genes [RESPONSE TO ANTAGONIST 1 (RAN1), ETHYLENE RESPONSE 1 (ETR1), ETHYLENE INSENSITIVE 2 (EIN2), EIN3 and ARABIDOPSIS RESPONSE REGULATOR 2 (ARR2)], NADPH oxidase genes [ATRBOHD and ATRBOHF], and nitrate reductase genes (NIA1 and NIA2). Furthermore, SA-triggered ROS production in guard cells was impaired in ran1, etr1, AtrbohD and AtrbohF, but not in ein2, ein3 or arr2. SA-triggered NO production was impaired in all ethylene-signaling mutants tested and in nia1 and nia2. The stomata of mutants for CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) showed constitutive ROS and NO production and closure. These results indicate that ethylene mediates SA-induced stomatal closure by activating ATRBOHD/F-mediated ROS synthesis in an RAN1-, ETR1- and CTR1-dependent manner. This in turn induces NIA1/2-mediated NO production and subsequent stomatal closure via the ETR1, EIN2, EIN3 and ARR2-dependent pathway(s).

A propósito del Covid-19. El rol de la edad y género en la inmunidad

The purpose of the immune system is to protect the body from pathogenic microorganisms
 such as bacteria, viruses, fungi and even tumor cells, which could cause disease. When the
 encounter with pathogens occurs, defenses are produced immediately through the innate
 response, faster and more nonspecific, and through the adaptive response, more defined and
 personalized for each attacker. Both are triggered by the cells of the immune system being
 able to communicate with each other, once they have been activated. The innate immune
 system works in tune with the acquired immune system through the close intervention of the
 sex hormones, with specific strategies of estrogen and progesterone. Both have a proven
 anti-inflammatory and antioxidant action not only at the level of the wall of blood vessels, skin
 and mucous membranes, but also in the protection of the central nervous system against all
 toxic agents, such as viruses. Estrogens and progesterone play an essential role in the immune
 response and its evolution, and although they initially appear as antagonistic responses, they
 are not, despite the fact that estrogens increase and progesterone seems to suppress the
 immune response, depending on the immune target according to the case.

Olaparib Combined with an ATR or Chk1 Inhibitor as a Treatment Strategy for Acquired Olaparib-Resistant BRCA1 Mutant Ovarian Cells.

Objective: Despite the promise of PARP inhibitors (PARPi) for treating BRCA1/2 mutated ovarian cancer (OC), drug resistance invariably develops. We hypothesized rationale drug combinations, targeting key molecules in DNA repair pathways and the cell cycle may be synergistic and overcome acquired PARPi resistance. Methods: Drug sensitivity to PARPi alone and in combination with inhibitors of key DNA repair and cell cycle proteins, including ATR (VE-821), Chk1 (MK-8776), Wee1 (MK-1775), RAD51 (RI-1) was assessed in PARPi-sensitive (UWB1) and -resistant (UWB1-R) gBRCA1 mutant OC cell lines using a cell proliferation assay. The Bliss synergy model was used to estimate the two-drug combination effect and pharmacologic synergy (Bliss score ≥ 0) or antagonistic (Bliss score ≥ 0) response of the PARPi in combination with the inhibitors. Results: IC50 for olaparib alone was 1.6 ± 0.9 µM compared to 3.4 ± 0.6 µM (p = 0.05) for UWB1 and UWB1-R cells, respectively. UWB1-R demonstrated increased sensitivity to ATRi (p = 0.04) compared to UWB1. Olaparib (0.3–1.25 µM) and ATRi (0.8–2.5 µM) were synergistic with Bliss scores of 17.2 ± 0.2, 11.9 ± 0.6 for UWB1 and UWB1-R cells, respectively. Olaparib (0.3–1.25 µM) and Chk1i(0.05–1.25 µM) were synergistic with Bliss scores of 8.3 ± 1.6, 5.7 ± 2.9 for UWB1 and UWB1-R cells, respectively. Conclusions: Combining an ATRi or Chk1i with olaparib is synergistic in both PARPi-sensitive and -resistant BRCA1 mutated OC cell models, and are rationale combinations for further clinical development.

Differential Accumulation of Innate- and Adaptive-Immune-Response-Derived Transcripts during Antagonism between Papaya Ringspot Virus and Papaya Mosaic Virus.

Papaya ringspot virus (PRSV), a common potyvirus infecting papaya plants worldwide, can lead to either antagonism or synergism in mixed infections with Papaya mosaic virus (PapMV), a potexvirus. These two unrelated viruses produce antagonism or synergism depending on their order of infection in the plant. When PRSV is inoculated first or at the same time as PapMV, the viral interaction is synergistic. However, an antagonistic response is observed when PapMV is inoculated before PRSV. In the antagonistic condition, PRSV is deterred from the plant and its drastic effects are overcome. Here, we examine differences in gene expression by high-throughput RNA sequencing, focused on immune system pathways. We present the transcriptomic expression of single and mixed inoculations of PRSV and PapMV leading to synergism and antagonism. Upregulation of dominant and hormone-mediated resistance transcripts suggests that the innate immune system participates in synergism. In antagonism, in addition to innate immunity, upregulation of RNA interference-mediated resistance transcripts suggests that adaptive immunity is involved.

Insect herbivory antagonizes leaf cooling responses to elevated temperature in tomato

As global climate change brings elevated average temperatures and more frequent and extreme weather events, pressure from biotic stresses will become increasingly compounded by harsh abiotic stress conditions. The plant hormone jasmonate (JA) promotes resilience to many environmental stresses, including attack by arthropod herbivores whose feeding activity is often stimulated by rising temperatures. How wound-induced JA signaling affects plant adaptive responses to elevated temperature (ET), however, remains largely unknown. In this study, we used the commercially important crop plant Solanum lycopersicum (cultivated tomato) to investigate the interaction between simulated heat waves and wound-inducible JA responses. We provide evidence that the heat shock protein HSP90 enhances wound responses at ET by increasing the accumulation of the JA receptor, COI1. Wound-induced JA responses directly interfered with short-term adaptation to ET by blocking leaf hyponasty and evaporative cooling. Specifically, leaf damage inflicted by insect herbivory or mechanical wounding at ET resulted in COI1-dependent stomatal closure, leading to increased leaf temperature, lower photosynthetic carbon assimilation rate, and growth inhibition. Pharmacological inhibition of HSP90 reversed these effects to recapitulate the phenotype of a JA-insensitive mutant lacking the COI1 receptor. As climate change is predicted to compound biotic stress with larger and more voracious arthropod pest populations, our results suggest that antagonistic responses resulting from a combination of insect herbivory and moderate heat stress may exacerbate crop losses.

Circuit Mechanisms Underlying Chromatic Encoding in Drosophila Photoreceptors.

Spectral information is commonly processed in the brain through generation of antagonistic responses to different wavelengths. In many species, these color opponent signals arise as early as photoreceptor terminals. Here, we measure the spectral tuningof photoreceptors in Drosophila. In addition to a previously described pathway comparing wavelengths at each point in space, we find a horizontal-cell-mediated pathway similar to that found in mammals. This pathway enables additional spectral comparisons through lateral inhibition, expanding the range of chromatic encoding in the fly. Together, these two pathways enable efficient decorrelation and dimensionality reduction of photoreceptor signals while retaining maximal chromatic information. A biologically constrained model accounts for our findings and predicts a spatio-chromatic receptive field for fly photoreceptor outputs, with a color opponent center and broadband surround. This dual mechanism combines motifs of both an insect-specific visual circuit and an evolutionarily convergent circuit architecture, endowing flies with the ability to extract chromatic information at distinct spatial resolutions.

Effect-Directed Analysis of Progestogens and Glucocorticoids at Trace Concentrations in River Water.

Effect-based monitoring is increasingly applied to detect and-in conjunction with chemical analysis-to identify endocrine-disrupting compounds (EDCs) in the environment. Although this approach of effect-directed analysis has been successfully demonstrated for estrogenicity and androgenicity, data on progestogens and glucocorticoids driving endocrine disruption are quite limited. We investigated progestogenic and glucocorticoid activities in Danube River water receiving untreated wastewater from Novi Sad, Serbia. After a 2-step fractionation, all fractions were tested with reporter gene bioassays for agonistic and antagonistic hormonal responses at progestogenic and glucocorticoid hormone receptors as well as with target and nontarget analytical screening of active fractions by liquid chromatography-high-resolution mass spectrometry. Due to masking by cytotoxic mixture components, the effects could not be detected in the raw water extract but were unraveled only after fractionation. Target chemical screening of the fraction that was active in the progesterone receptor (PR) assay revealed that progesterone and megestrol acetate were predominant drivers of PR-mediated activity along with medroxyprogesterone, dihydrotestosterone, androsterone, and epiandrosterone. Hydrocortisone was detected at sub-ng/L concentration in the active fraction in the glucocorticoid receptor (GR) assay but could not explain a significant fraction of the observed GR activity. The present study indicates that effect-based monitoring is a powerful tool to detect EDCs in the aquatic environment but that fractionation may be required to avoid masking effects of mixture components. Future effect-directed analysis studies are required to better understand the occurrence of EDCs and masking compounds in different lipophilicity windows, to finally reduce fractionation requirements for monitoring to a smart clean-up. Environ Toxicol Chem 2019;39:189-199. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

PI3Kδ Inhibition Enhances Sensitivity of Primary High-Risk Childhood B-Cell Acute Lymphoblastic Leukemia Cells to Glucocorticoid Chemotherapy

Introduction: Despite excellent 5-year survival for most patients with B-cell acute lymphoblastic leukemia (B-ALL), those with high-risk (HR) B-ALL continue to have inferior outcomes. The prognosis is even worse for patients who respond poorly to chemotherapy, and improvements to current therapy approaches are needed. Glucocorticoids (GCs) are a key component of chemotherapy regimens. Rapid response to GC monotherapy is a well-documented predictor of favorable outcomes, while slow response to GCs correlates with poor outcomes. We hypothesized that enhancing specific GC toxicity to B-ALL cells can improve clinical outcomes for high-risk patients without increasing systemic toxicity. PI3Kδ is a promising target for this purpose. PI3Kδ is a critical component of the B-cell receptor cell-survival pathway; it restrains GC signaling, while GCs repress its expression. PI3Kδ expression is restricted to lymphoid cells, making it an appealing precision target to enhance GC toxicity in lymphoid cells while minimizing risk of increased systemic GC-associated toxicity. We previously demonstrated synergy between dexamethasone (dex) and the FDA-approved isoform-selective PI3Kδ inhibitor idelalisib (idela) in B-ALL cell lines, patient specimens, and patient-derived xenograft models (Kruth et al Blood 2017). In clinical practice, both dex and prednisone (pred) are essential components of childhood ALL chemotherapy. In this study, we sought to elucidate the extent to which idela in combination with dex or pred could induce synergistic killing of HR B-ALL specimens with various genetic backgrounds. Methods: Peripheral blood or bone marrow from patients ages 1-31 years with newly-diagnosed NCI HR or standard-risk (SR) B-ALL at the University of Iowa Stead Family Children's Hospital was obtained after informed consent on an Institutional Review Board-approved research study. Mononuclear cells were isolated from the specimens via Ficoll gradients and cultured in vitro in 384-well plates. Immediately after isolation, cells were treated with serial dilutions of the GCs dex or pred and idela in RPMI1640+10% FBS medium. Cell viability was measured with PrestoBlue (Invitrogen) after 72 hours of treatment. Survival curves were plotted to determine the LD50 of each drug using GraphPad. Dose effects around the LD50 for each drug were analyzed using Compusyn to determine if the drug combination was synergistic (combination index, CI <1), additive (CI=1), or antagonistic (CI >1). Results: As of August 1, 2019, 5 HR B-ALL patient specimens of various genetic alterations have been tested. Two patients were high-risk at diagnosis due to steroid pre-treatment (MAP011) or by NCI risk criteria (age >10 years and/or WBC count >50K/mm3; MAP014). Three patients with initially SR B-ALL were upstaged due to minimal residual disease (MRD) >1% at day 8 in peripheral blood (MAP012) or marrow MRD ≥0.01% at end of induction (MAP009, MAP010). In our in vitro studies, only one sample (MAP014) showed reduced viability with GC alone, while 4 specimens (all except MAP012) responded to idela alone. Most specimens showed a synergistic response to dex or pred in combination with idela with greater reduction in cell viability compared to GC monotherapies. Surprisingly, one specimen (MAP010) had an antagonistic response with pred and idela combination. This near-haploid B-ALL specimen had reduced viability with idela monotherapy, but an antagonistic response with single-agent pred, raising the question of whether GC/idela synergy is influenced by genetic background. Conclusions: In pilot studies, idela sensitized HR B-ALL cells to GC chemotherapy and is a promising strategy for further evaluation in a larger cohort of specimens. Our results highlight the potential impact of genetic heterogeneity within childhood B-ALL upon differential therapeutic responses to standard steroid chemotherapy and demonstrate a potential precision medicine approach to augment GC sensitivity via combination with selective PI3Kδ inhibition. Disclosures Tasian: Gilead Sciences: Research Funding; Aleta Biotherapeutics: Membership on an entity's Board of Directors or advisory committees; Incyte Corportation: Research Funding.

Synergistic immuno-modulatory activity in human macrophages of a medicinal mushroom formulation consisting of Reishi, Shiitake and Maitake.

A key characteristic of mushroom polysaccharides that elicit an immunomodulatory response is that they are rich in β-glucans and low in α-glucans. In this study we analysed nine commercially available preparations from three mushroom species, Reishi (Ganoderma lucidum), Shiitake (Lentinula edodes) and Maitake (Grifola frondosa), for β- and α-glucan content. Based on β- and α-glucan content we selected three extracts to combine into a formula and evaluated the ability of the individual extracts and formula to impact on the expression of cytokines IL-1α, IL-6, IL-10 and TNF-α in human macrophages with and without LPS stimulation. The majority of mushroom extracts and the formula were found to be highly potent immuno-stimulators possessing EC50 values lower than 100 μg/mL. Interestingly the mushroom formula had lower EC50 values in TNF-α expression from LPS stimulated macrophages compared to the individual extracts, suggesting a potential synergistic effect of the mushroom formula. A response additivity graph and curve-shift analysis illustrated that indeed the mushroom formula exhibited an immuno-stimulatory synergistic effect on the expression of the majority of cytokines evaluated in both LPS stimulated and non-stimulated human macrophages, with IL-10 having an antagonistic response. This study represents the first report of a synergistic immuno-modulatory response in human macrophages elicited from a mushroom formula rationally derived from β- and α-glucan content.

Exploring the Social Impacts of Wildlife Conservation in Ethiopia: Past Experiences and Future Directions

Establishing protected areas is a predominant wildlife conservation effort across Africa. Such strategy, however, has inevitable social and economic impacts to the local people. Social impacts and conservation require equal attention because it is the foundations for alliances with social groups to address common concerns. This makes social impact assessment a very crucial tool to understand the long run impacts of wildlife conservation on local people. Surprisingly, such analysis is insufficient and seemingly uncommon practices in Ethiopia. This short review examines scarcely available literatures on these matters and suggests the ways to maximize the positive and minimize the negative impacts of the sector. It is hard to understand the policies and positions of conservation sectors of Ethiopia on social impacts of conservation. Positive social impacts of conservation range from employment opportunities, improved infrastructural development to monetary gains. Negative social impacts include human displacement, lack of resource access, conflicts arising from enforcement activities, and human-wildlife conflicts. Several studies from different parts of Ethiopia have indicated the alienation of the local community and their subsequent antagonistic responses towards conservation efforts. Integrating conservation programs and local community minimizes the costs and increases the benefits of the local people. These in turn raise the social acceptance and success of the program. Wildlife conservation in Ethiopia still requires a detailed studies and practical improvements to equally address the social and biological needs of the sector. Keywords: Costs of wildlife conservation, Ethiopia, Human displacement, Human-wildlife conflicts, Local community, Wildlife conservation DOI : 10.7176/JRDM/61-03 Publication date: November 30 th 2019

Plasma cytokine profiles associated with rhodesiense sleeping sickness and falciparum malaria co-infection in North Eastern Uganda

BackgroundImmunological Human African Trypanosomiasis (HAT) studies often exclude malaria, although both infections overlap in specific endemic areas. During this co-infection, it is not known whether this parasitic interaction induces synergistic or antagonistic cytokine response among humans. This study determined prevalence of Plasmodium falciparum malaria among Trypanosoma brucei rhodesiense HAT and plasma cytokine profile levels associated with HAT and/or malaria infections.MethodsParticipants were recruited at Lwala hospital in north eastern Uganda: healthy controls (30), malaria (28), HAT (17), HAT and malaria (15) diagnosed by microscopy and PCR was carried out for parasite species identification. Plasma cytokine levels of Interferon-gamma (IFN-γ), Tumour Necrosis Factor-alpha (TNF-α), Interleukin (IL)-6, IL-10 and Transforming Growth Factor-beta (TGF-β) were measured by sandwich Enzyme-Linked Immuno Sorbent Assay and data statistically analysed using Graphpad Prism 6.0.ResultsThe prevalence of P. falciparum malaria among T. rhodesiense HAT cases was high (46.8%). Malaria and/or HAT cases presented significant higher plasma cytokine levels of IFN-γ, TNF-α, IL-6, IL-10 and TGF-β than healthy controls (P < 0.05). Levels of IFN-γ, IL-6 and IL-10 were significantly elevated in HAT over malaria (P < 0.05) but no significant difference in TNF-α and TGF-β between HAT and malaria (P > 0.05). Co-infection expressed significantly higher plasma IFN-γ, IL-6, and IL-10 levels than malaria (P < 0.05) but no significant difference with HAT mono-infection (P > 0.05). The TNF-α level was significantly elevated in co-infection over HAT or malaria mono-infections (P < 0.05) unlike TGF-β level. Significant positive correlations were identified between IFN-γ verses TNF-α and IL-6 verses IL-10 in co-infection (Spearman’s P < 0.05).ConclusionsThe T. b. rhodesiense significantly induced the cytokine response more than P. falciparum infections. Co-infection led to synergistic stimulation of pro-inflammatory (IFN-γ, TNF-α), and anti-inflammatory (IL-6, and IL-10) cytokine responses relative to malaria mono-infection. Level of TNF-α partially indicates the effect induced by T. b. rhodesiense and P. falciparum mono-infections or a synergistic interaction of co-infections which may have adverse effects on pathogenesis, prognosis and resolution of the infections.Trial registration VCD-IRC/021, 26/08/2011; HS 1089, 16/01/2012

Acute and chronic toxicity of herbicides and their mixtures measured by Aliivibrio fischeri ecotoxicological assay

The purpose of our work was to determine the acute and chronic toxicity of three of the EU's most common herbicides - mesotrione, S-metolachlor, terbuthylazine - and their mixtures by Aliivibrio fischeri ecotoxicological assays. While comparing the sensitivity of the acute (30 min) Microtox® standard assay with the chronic (25 h) test adapted to microtiter plate, joint effects (antagonism, additive effect and synergism) to the bioluminescence inhibition (consequently the metabolic damage) in A. fischeri were also determined by Combination Index (CI) method. 30 min of exposure to mesotrione and S-metolachlor resulted in a relatively low acute toxicity (EC50 values were 118 and 265 mg/L), while terbuthylazine did not cause bioluminescence inhibition at all. Results showed that the chronic toxicity of S-metolachlor and terbuthylazine to A. fischeri (EC5010h = 59.2 and 4.9 mg/L and EC5015h = 54.0 and 9.6 mg/L, respectively) is larger by at least one order of magnitude than that after 30 min of contact time. Considering mesotrione no significant difference was experienced in toxicity. Regarding the EC50 values, all of the mixtures had synergistic joint effects in the acute assay. However, in the chronic test all the mixtures showed antagonistic responses with the exception of mesotrione and S-metolachlor (ratio 1:1) combination, which also had additive and synergistic effects after 10 and 15 h of exposure, similarly to the short-term test. This is also the first report of the joint effects of these herbicides. The chronic test is a more sensitive indicator to the active ingredients; both acute and chronic assays supply valuable data of the toxic properties of the pesticides. Moreover, the short- and long-term joint effects of their mixtures supporting a more accurate and reliable risk assessment.

307 The Association Between Immune Dysfunction and Outcome of Septic Patients: A Prospective Observational Study

Sepsis is a dysregulated host response to an infection or injury which features as a multiple-system failure. Immune mechanism plays a vital role in the pathogenesis of sepsis. Some immune status might exist in septic patients, such as systemic inflammatory response syndrome (SIRS), compensatory anti-inflammatory response syndrome (CARS) and mixed antagonistic response syndrome (MARS), which is a severe imbalance of pro- and anti-inflammatory activities. The objective of this study is to explore the association between prognosis of sepsis and immune markers, namely pro-inflammatory markers such as tumor necrosis factor (TNF)-α, interleukin (IL)-2R, IL-6, IL-8, and anti-inflammatory markers such as IL-10, CD14+ monocyte human leukocyte antigen-D related (HLA-DR) expression. Also, the prognosis of each immune status was also targeted. A prospective observational study was carried out in Zhongshan Hospital, Fudan University, enrolling septic patients admitted between October 2016 and December 2018. Peripheral blood samples of patients were collected at day 1, day 3 and day 7 after admission. Medical records were screened for available clinical data. Plasma cytokines level were measured by enzyme-linked immunosorbent assay (ELISA) method and the flow cytometry was performed to measure the CD14+ monocyte HLA-DR expression. The median value of each immune marker was used as the cut-off point. Level of a pro-inflammatory marker higher than cut-point was marked as (+) , so was an anti-inflammatory marker lower than cut-point. Otherwise, it was marked as (-). Immune status of sepsis was classified according to levels of immune markers. SIRS was defined as 0-4 pro-inflammatory markers(+) and 0 anti-inflammatory markers(+). CARS was defined as 0-2 pro-inflammatory markers(+) and 1-2 anti-inflammatory marker(+). MARS was defined as 3-4 pro-inflammatory markers(+) and 1-2 anti-inflammatory marker(+). We analyzed the association between in-hospital mortality of septic patients and immune markers, as well as three immune status. Statistical analysis was conducted on SPSS 25.0 A total of 174 septic patients were enrolled in the study, among whom 124 survived and 50 did not. Immune markers were significantly associated with outcomes of sepsis (TNF-α: P<0.01 at day 1, P<0.001 at day 3; IL-2R: P=0.013 at day 1, P=0.029 at day 3; IL-6: P<0.001 at day 1 and day 3;IL-8:P<0.001 at day1 and day 3, P=0.023; IL-10: P<0.001 at day1 and day 3,P=0.006 at day 7; HLA-DR expression: P<0.001 at day1 and day 3). MARS caused higher in-hospital mortality than SIRS and CARS (P<0.001). Survival analysis also revealed that patients with MARS had poor 30-day survival than patients with SIRS and CARS (Log-rank test: P<0.001). Immune markers such as plasma cytokines level and CD14+ monocyte HLA-DR expression were associated with prognosis of septic patients. Patients with severe immune disorder, defined as MARS, could be predictive of poor outcome.

Speed and Politics: Domitian andceleritasin Statius’sSilvae

AbstractStatius’s self-professed speed of production (celeritas) in the Silvae is often understood as an antagonistic response to Callimachean and neoteric poetics and a reflection of Flavian culture’s penchant for extempore production. While undoubtedly true, this article argues that Statius’s celeritas gains fuller meaning when held up against the traditional Roman valorization of military speed, the clearest representative of which was Julius Caesar. This has interesting ramifications when we consider the importance of Domitian’s complicated self-presentation as an exemplary military leader, which Flavian poets appropriated in various ways. Ultimately, Lucan’s troubling portrayal of Julius Caesar in the Bellum Civile lingers in the background of the Silvae, making any profession of poetic and military celeritas an ambiguous, and possibly dangerous, topic.

Cumulative Effects of Disturbances on Soil Nutrients: Predominance of Antagonistic Short-Term Responses to the Salvage Logging of Insect-Killed Stands

Nutrient cycling generally recovers rapidly following disturbance in forest ecosystems. Concerns have been expressed that the resilience of this function may be altered by enhanced disturbance frequency, and especially by the use of salvage logging. A sudden hemlock looper (Lambdina fiscellaria) outbreak in a boreal forest leading to tree mortality in discrete patches allowed us to evaluate the impact of disturbance type (logging vs insect defoliation) as well as the cumulative effects of both disturbances (that is, salvage logging of defoliated sites) on soil nutrients, providing a rare opportunity to test for interactions between these two disturbances. We assessed, within 2–3 years following treatments, whether both individual disturbances had distinct effects on soils properties and whether their cumulative effects were either additive, synergistic or antagonistic. Defoliation generally increased the soil nutrient concentrations, especially of soluble nitrogen forms, when compared to the undisturbed controls. The spatial heterogeneity of soil nutrient concentrations was also much greater in defoliated stands than in the other treatments. Logging alone had an effect that was less variable and generally of lower amplitude than defoliation. Contrary to what was expected, salvage logging led to soil properties that were more similar to those of undisturbed controls, indicating that antagonistic interactions occurred. Our results showed that, under the conditions of this study, salvage logging could reduce the potential for soil nutrient leaching and lead to more homogenous soil conditions. These results bring new light on the effect of cumulative disturbances and could be useful to guide post-disturbance forest management decisions.

Piper cernuum Vell.: Chemical profile and antimicrobial potential evaluation

In this study, the Piper cernuum Essential Oil (EOPC) was tested against bacterial and fungal strains using the microdilution method to evaluate its minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC), as well as its antibiotic modifying effect, in addition to observing the oils ability to cause fungal dimorphism and to generate an IC50 cell viability curve. The EO was obtained through hydrodistillation using a Clevenger-type apparatus with the dry leaves and analyzed by GC-FID, allowing the identification of 14 compounds, with the main compound being 4-epi-cis-dihydromarofuran (28.97%). An EOPC intrinsic activity was identified only against Candida albicans 4127 (IC50 56.851 μg/mL). Given the MIC results from the EOPC intrinsic activity against Staphylococcus aureus 10 at the concentration of 406 μg/mL, its association with fluconazole potentiated it’s antifungal action. The action of gentamicin was potentiated by the addition of the EOPC to Staphylococcus aureus 10 and Escherichia coli 06 strains, both with MIC < 40 μg/ml, however, when the EOPC was combined with other antibiotics against Staphylococcus aureus 10 they presented an antagonistic response. When the EOPC was tested with the antibiotic norfloxacin against the Gram-negative Escherichia coli 06 strain an antagonistic response was also found. The EOPC inhibited fungal dimorphism, reducing the virulence of these strains, with this effect being better than that of fluconazole. These results highlight the species as a promising source of active antimicrobial compounds.

Environmentally Relevant Concentrations of Bisphenol A Interact with Doxorubicin Transcriptional Effects in Human Cell Lines.

The worldwide production of synthetic chemicals, including endocrine disruptor chemicals (EDCs), such as Bisphenol A (BPA) has increased significantly in the last two decades. Human exposure to BPA, particularly through ingestion, is continuous and ubiquitous. Although, considered a weak environmental estrogen, BPA can induce divergent biological responses through several signaling pathways, including carcinogenesis in hormone-responsive organs. However, and despite the continuous increase of tumor cell-resistance to therapeutic drugs, such as doxorubicin (DOX), information regarding BPA drug interactions is still scarce, although its potential role in chemo-resistance has been suggested. This study aims to assess the potential interactions between environmentally relevant levels of BPA and DOX at a therapeutic dosage on Hep-2 and MRC-5 cell lines transciptome. Transcriptional effects in key-player genes for cancer biology, namely c-fos, p21, and bcl-xl, were evaluated through qRT-PCR. The cellular response was analyzed after exposure to BPA, DOX, or co-exposure to both chemicals. Transcriptional analysis showed that BPA exposure induces upregulation of bcl-xl and endorses an antagonistic non-monotonic response on DOX transcriptional effects. Moreover, the BPA interaction with DOX on c-fos and p21 expression emphasize its cellular specificity and divergent effects. Overall, Hep-2 was more susceptible to BPA effects in a dose-dependent manner while MRC-5 transcriptional levels endorsed a non-monotonic response. Our data indicate that BPA environmental exposure may influence chemotherapy outcomes, which emphasize the urgency for a better understanding of BPA interactions with chemotherapeutic agents, in the context of risk assessment.

Molecular evolution of the switch for progesterone and spironolactone from mineralocorticoid receptor agonist to antagonist

The mineralocorticoid receptor (MR) is highly conserved across vertebrate evolution. In terrestrial vertebrates, the MR mediates sodium homeostasis by aldosterone and also acts as a receptor for cortisol. Although the MR is present in fish, they lack aldosterone. The MR binds progesterone and spironolactone as antagonists in human MR but as agonists in zebrafish MR. We have defined the molecular basis of these divergent responses using MR chimeras between the zebrafish and human MR coupled with reciprocal site-directed mutagenesis and molecular dynamic (MD) simulation based on the crystal structures of the MR ligand-binding domain. Substitution of a leucine by threonine in helix 8 of the ligand-binding domain of the zebrafish MR confers the antagonist response. This leucine is conserved across fish species, whereas threonine (serine in rodents) is conserved in terrestrial vertebrate MR. MD identified an interaction of the leucine in helix 8 with a highly conserved leucine in helix 1 that stabilizes the agonist conformation including the interaction between helices 3 and 5, an interaction which has previously been characterized. This switch in the MR coincides with the evolution of terrestrial vertebrates and of aldosterone synthesis. It was perhaps mandatory if the appearance of aldosterone as a specific mediator of the homeostatic salt retention was to be tolerated. The conformational changes also provide insights into the structural basis of agonism versus antagonism in steroid receptors with potential implications for drug design in this important therapeutic target.

Connectomic Identification and Three-Dimensional Color Tuning of S-OFF Midget Ganglion Cells in the Primate Retina.

In the trichromatic primate retina, the "midget" retinal ganglion cell is the classical substrate for red-green color signaling, with a circuitry that enables antagonistic responses between long (L)- and medium (M)-wavelength-sensitive cone inputs. Previous physiological studies showed that some OFF midget ganglion cells may receive sparse input from short (S)-wavelength-sensitive cones, but the effect of S-cone inputs on the chromatic tuning properties of such cells has not been explored. Moreover, anatomical evidence for a synaptic pathway from S cones to OFF midget ganglion cells through OFF midget bipolar cells remains ambiguous. In this study, we address both questions for the macaque monkey retina. First, we used serial block-face electron microscopy to show that every S cone in the parafoveal retina synapses principally with a single OFF midget bipolar cell, which in turn forms a private-line connection with an OFF midget ganglion cell. Second, we used patch electrophysiology to characterize the chromatic tuning of OFF midget ganglion cells in the near peripheral retina that receive combined input from L, M, and S cones. These "S-OFF" midget cells have a characteristic S-cone spatial signature, but demonstrate heterogeneous color properties due to the variable strength of L, M, and S cone input across the receptive field. Together, these findings strongly support the hypothesis that the OFF midget pathway is the major conduit for S-OFF signals in primate retina and redefines the pathway as a chromatically complex substrate that encodes color signals beyond the classically recognized L versus M and S versus L+M cardinal mechanisms.SIGNIFICANCE STATEMENT The first step of color processing in the visual pathway of primates occurs when signals from short (S)-, middle (M)-, and long (L)-wavelength-sensitive cone types interact antagonistically within the retinal circuitry to create color-opponent pathways. The midget (L versus M or "red-green") and small bistratified (S vs L+M, or "blue-yellow") ganglion cell pathways appear to provide the physiological origin of the cardinal axes of human color vision. Here we confirm the presence of an additional S-OFF midget circuit in the macaque monkey fovea with scanning block-face electron microscopy and show physiologically that a subpopulation of S-OFF midget cells combine S, L, and M cone inputs along noncardinal directions of color space, expanding the retinal role in color coding.

Modulation of intracortical inhibition and excitation in agonist and antagonist muscles following acute strength training.

Transcranial magnetic stimulation (TMS) usually investigates the corticospinal responses of the agonist muscle to strength training, despite the role of the antagonist muscle in strength development. We examined the intracortical responses from an agonist and antagonist muscle following a single session of heavy-loaded strength training (dominant-arm only) to identify the early antagonistic responses to a single session that may accompany improvements in strength. Corticospinal and motor cortical excitability and inhibition was collected from agonist and antagonist muscles prior to and following a single session of heavy-loaded wrist flexor training in 18 individuals. Training consisted of four sets 6-8 repetitions at 80% of 1-repetition maximum (1-RM). Recruitment curves for corticospinal excitability and inhibition of the right wrist flexor and wrist extensor muscles were constructed and assessed by examining the area under the recruitment curve. Intracortical measures were obtained using paired-pulse TMS. Following a single training session, increases in corticospinal excitability were observed in both the agonist and antagonist muscles. This was accompanied by decreases in corticospinal inhibition in both muscles. Intracortical inhibition was reduced and intracortical facilitation was increased for the agonist muscle only. Intracortical measures in the antagonist muscle remained unchanged after training. These findings indicate that the corticospinal responses to a single session of strength training are similar between agonist and antagonist muscles, but the intrinsic cortico-cortical circuitry of the antagonist remains unchanged. The corticospinal responses are likely due to increased involvement/co-activation of the antagonist muscle during training as the agonist muscle fatigues.