Mechanisms modulating foam cell formation in the arterial intima: exploring new therapeutic opportunities in atherosclerosis.

In recent years, the role of macrophages as the primary cell type contributing to foam cell formation and atheroma plaque development has been widely acknowledged. However, it has been long recognized that diffuse intimal thickening (DIM), which precedes the formation of early fatty streaks in humans, primarily consists of lipid-loaded smooth muscle cells (SMCs) and their secreted proteoglycans. Recent studies have further supported the notion that SMCs constitute the majority of foam cells in advanced atherosclerotic plaques. Given that SMCs are a major component of the vascular wall, they serve as a significant source of microvesicles and exosomes, which have the potential to regulate the physiology of other vascular cells. Notably, more than half of the foam cells present in atherosclerotic lesions are of SMC origin. In this review, we describe several mechanisms underlying the formation of intimal foam-like cells in atherosclerotic plaques. Based on these mechanisms, we discuss novel therapeutic approaches that have been developed to regulate the generation of intimal foam-like cells. These innovative strategies hold promise for improving the management of atherosclerosis in the near future.

Proximate analysis and GC-MS phytochemical profiling of aqueous extracts of Doryopteris raddiana, a plant used by the Mbya-Guaraní as a contraceptive.

Doryopteris raddiana (Presl) Fée, a traditional contraceptive in Mbya culture, lacks scientific scrutiny regarding its chemical composition and contraceptive efficacy. Employing X-ray fluorescence, Fourier-transform infrared spectroscopy, and thermal analysis, we explored the plant's organs. Multielemental analysis excluded toxic elements. Key phytoconstituents identified by gas chromatography-mass spectrometry in the extracts obtained through infusion were glycerine, 1,3-dimethyl propane, and catechol in leaves; glycerine, cis-13-octadecenoic acid methyl ester, and 2-deoxy-D-erythro-pentose in stems and roots. Among these chemicals, glycerine emerged as the sole constituent with contraceptive potential, particularly intravaginally. Extract activity tests conducted on ram spermatozoa exhibited a reduction in the percentage of rapid spermatozoa but no significant impact on total motility, progressive motility, or viability. The reported data would only weakly support the advocated contraceptive action of this fern upon vaginal application, not through the oral administration of its decoction.

Increased Prevalence of the Electrocardiographic Early Repolarization Pattern in Young Patients With Vagally Mediated Syncope: A Case-Control Study.

Background: Electrocardiographic early repolarization (EER) is linked with idiopathic ventricular fibrillation in adults. It is frequently seen in children, with poorly understood significance. Some evidence suggests that it could be a vagally mediated phenomenon. A retrospective case-control study was undertaken to test the hypothesis that EER is more common among children with typical vasovagal syncope (VVS) than among their peers with nonvagal syncope (NVS) or with no syncope. Methods: Patients aged 4-18 years with syncope were identified by a single-centre database search followed by a review of history for features of VVS (n = 150) or NVS (n = 84). The first available electrocardiogram (ECG) for VVS or for NVS was retrieved. Age- and sex-matched children with no known syncope or heart disease were then identified (n = 216). ECGs were assessed separately for EER based on published criteria by 2 observers blinded to patients' clinical status. Results: Mean age was 12.3 ± 3.2 years, and heart rate was 74.2 ± 16.5 beats/min. EER was more prevalent in VVS (33.3%) than among patients with NVS (19.1%; odds ratio: 2.29; confidence interval: 1.32-5.50) or among those with no syncope (12.5%; odds ratio: 3.14; confidence interval: 1.81-5.46). Heart rates were significantly lower in VVS and NVS (heart rate: 70.1 ± 13.8 and 70.7 ± 12.4 beats/min, respectively) compared with children with no syncope (heart rate: 78.2 ± 18.0 beats/min), both P < 0.001. Conclusions: EER is more common in paediatric patients with VVS than those with NVS or without syncope, consistent with a possible vagal contribution to the ECG finding.

Contexte: La repolarisation précoce (RP) à l'électrocardiogramme (ECG) est liée à une fibrillation ventriculaire idiopathique chez les adultes. Fréquente chez les enfants, sa signification est toutefois nébuleuse. Certaines données laissent penser qu'il pourrait s'agir d'un phénomène d'origine vagale. Une étude rétrospective cas-témoins a donc été réalisée dans le but de vérifier l'hypothèse selon laquelle la RP à l'ECG est plus courante chez les enfants atteints de syncope vasovagale (SVV) typique que chez leurs pairs atteints de syncope non vagale (SNV) ou non atteints de syncope. Méthodologie: Des patients de 4 à 18 ans atteints de syncope ont été recensés au moyen d'une recherche dans la base de données d'un centre, suivie d'un examen des antécédents visant à retracer des manifestations de SVV (n = 150) ou de SNV (n = 84). Le premier ECG disponible traduisant une SVV ou une SNV a été récupéré. Un appariement selon l'âge et le sexe entre les sujets atteints et des enfants qui n'étaient pas atteints de syncope ni de maladie cardiaque (n = 216) a ensuite été effectué. Deux observateurs qui ne connaissaient pas l'état clinique des enfants ont évalué les ECG séparément, à la recherche d'une RP, en se basant sur les critères publiés. Résultats: L'âge moyen des sujets était de 12,3 ± 3,2 ans et la fréquence cardiaque moyenne, de 74,2 ± 16,5 battements/minute. La prévalence de la RP à l'ECG était plus élevée chez les patients atteints de SVV (33,3 %) que chez les patients atteints de SNV (19,1 %; rapport de cotes [RC] : 2,29; intervalle de confiance [IC] : 1,32-5,50) ou les enfants non atteints de syncope (12,5 %; RC : 3,14; IC : 1,81-5,46). La fréquence cardiaque (FC) était significativement plus faible chez les sujets atteints de SVV ou de SNV (FC : 70,1 ± 13,8 et 70,7 ± 12,4 battements/minute, respectivement), en comparaison des enfants non atteints de syncope (FC : 78,2 ± 18,0 battements/minute); p < 0,001 dans les deux cas. Conclusion: La repolarisation précoce à l'ECG est plus courante chez les enfants atteints de syncope vasovagale que chez les enfants atteints de syncope non vagale ou non atteints de syncope, ce qui concorde avec une possible composante vagale dans le tracé de l'ECG.

Cost-effectiveness of rimegepant oral lyophilisate compared to best supportive care for the acute treatment of migraine in the UK.

AIMS: Migraine is the most common disabling headache disorder and is characterized by recurrent throbbing head pain and symptoms of photophobia, phonophobia, nausea, and vomiting. Rimegepant 75 mg, an oral lyophilisate calcitonin gene-related peptide antagonist, is the first treatment approved for both the acute and preventative treatment of migraine, and the first acute therapy approved in over 20-years. The objective was to assess the cost-utility of rimegepant compared with best supportive care (BSC) in the UK, for the acute treatment of migraine in the adults with inadequate symptom relief after taking at least 2 triptans, or for whom triptans are contraindicated or not tolerated. MATERIALS AND METHODS: A de novo model was developed to estimate incremental costs and quality-adjusted life years (QALYs), structured as a decision tree followed by Markov model. Patients received rimegepant or BSC for a migraine attack and were assessed for response (pain relief at 2-h). Responders and non-responders followed different pain trajectories over 48-h cycles. Non-responders discontinued treatment while responders continued treatment for subsequent attacks, with a proportion discontinuing over time. Data sources included a post-hoc pooled analysis of the phase 3 acute rimegepant trials (NCT03235479, NCT03237845, NCT03461757), and a long-term safety study (NCT03266588). The analysis was conducted from the perspective of the UK National Health Service and Personal Social Services over a 20-year time horizon. RESULTS: Rimegepant resulted in an incremental cost-utility ratio (ICUR) of £10,309 per QALY gained vs BSC, which is cost-effectiveness at a willingness to pay threshold of £30,000/QALY. Rimegepant generated +0.44 incremental QALYs and higher incremental lifetime costs (£4,492). Improved QALYs for rimegepant were a result of less time spent with severe and moderate headache pain. CONCLUSION: This study highlights the economic value of rimegepant which was found to be cost-effective for the acute treatment of migraine in adults unsuitable for triptans.

A dynamical measure of the black hole mass in a quasar 11 billion years ago.

Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)1-3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase4-6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3)7. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-µas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 108 solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 1011 solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems.

Inbred SJL mice recapitulate human resistance to Cryptococcus infection due to differential immune activation.

IMPORTANCE: Cryptococcosis studies often utilize the common C57BL/6J mouse model. Unfortunately, infection in these mice fails to replicate the basic course of human disease, particularly hampering immunological studies. This work demonstrates that SJL/J mice can recapitulate human infection better than other mouse strains. The immunological response to Cryptococcus infection in SJL/J mice was markedly different from C57BL/6J and much more productive in combating this infection. Characterization of infected mice demonstrated strain-specific genetic linkage and differential regulation of multiple important immune-relevant genes in response to Cryptococcus infection. While our results validate many of the previously identified immunological features of cryptococcosis, we also demonstrate limitations from previous mouse models as they may be less translatable to human disease. We concluded that SJL/J mice more faithfully recapitulate human cryptococcosis serving as an exciting new animal model for immunological and genetic studies.

Unique territorial and sub-chromosomal organization revealed in the holocentric moth Bombyx mori.

The hallmarks of chromosome organization in multicellular eukaryotes are chromosome territories (CT), chromatin compartments, and different types of domains, including topologically associated domains (TADs). Yet, most of these concepts derive from analyses of organisms with monocentric chromosomes. Here we describe the 3D genome architecture of an organism with holocentric chromosomes, the silkworm Bombyx mori . At the genome-wide scale, B. mori chromosomes form highly separated territories and lack substantial trans contacts. As described in other eukaryotes, B. mori chromosomes segregate into an active A and an inactive B compartment. Remarkably, we also identify a third compartment, Secluded "S", with a unique contact pattern. Compartment S shows strong enrichment of short-range contacts and depletion of long-range contacts. It hosts a unique combination of genetic and epigenetic features, localizes at the periphery of CTs and shows developmental plasticity. Biophysical modeling shows that formation of such secluded domains requires a new mechanism - a high density of extruded loops within them along with low level of extrusion and compartmentalization of A and B. Together with other evidence of loop extrusion in interphase, this suggests SMC-mediated loop extrusion in this insect. Overall, our analyses highlight the evolutionary plasticity of 3D genome organization driven by a new combination of known processes.

Improving the design and conduct of aquatic toxicity studies with oils based on 20 years of CROSERF experience.

Laboratory toxicity testing is a key tool used in oil spill science, spill effects assessment, and mitigation strategy decisions to minimize environmental impacts. A major consideration in oil toxicity testing is how to replicate real-world spill conditions, oil types, weathering states, receptor organisms, and modifying environmental factors under laboratory conditions. Oils and petroleum-derived products are comprised of thousands of compounds with different physicochemical and toxicological properties, and this leads to challenges in conducting and interpreting oil toxicity studies. Experimental methods used to mix oils with aqueous test media have been shown to influence the aqueous-phase hydrocarbon composition and concentrations, hydrocarbon phase distribution (i.e., dissolved phase versus in oil droplets), and the stability of oil:water solutions which, in turn, influence the bioavailability and toxicity of the oil containing media. Studies have shown that differences in experimental methods can lead to divergent test results. Therefore, it is imperative to standardize the methods used to prepare oil:water solutions in order to improve the realism and comparability of laboratory tests. The CROSERF methodology, originally published in 2005, was developed as a standardized method to prepare oil:water solutions for testing and evaluating dispersants and dispersed oil. However, it was found equally applicable for use in testing oil-derived petroleum substances. The goals of the current effort were to: (1) build upon two decades of experience to update existing CROSERF guidance for conducting aquatic toxicity tests and (2) to improve the design of laboratory toxicity studies for use in hazard evaluation and development of quantitative effects models that can then be applied in spill assessment. Key experimental design considerations discussed include species selection (standard vs field collected), test substance (single compound vs whole oil), exposure regime (static vs flow-through) and duration, exposure metrics, toxicity endpoints, and quality assurance and control.

The Challenges of Characterizing the Zooplankton Community Response Following Simulated Spills of Diluted Bitumen into Boreal Lake Limnocorrals.

We attempted to characterize zooplankton community response following spills of the unconventional crude oil, diluted bitumen (dilbit), into 10-m diameter, ~ 100 m3, ~ 1.5-m deep boreal lake limnocorrals, including two controls and seven dilbit treatments ranging from 1.5 to 180 L (1:100,000 to 1:1,000 v/v, dilbit:water). Community composition and abundances were monitored weekly to bi-weekly over three months. Total zooplankton biomass and abundance seemingly collapsed in all limnocorrals, regardless of treatment, though some rotifer species persisted. As a result, it was not possible to determine the impacts of dilbit. We theorize several potential non-oil-related reasons for the sudden community collapse - including elevated zinc levels, fish grazing pressures, and sampling biases - and provide guidance for future work using in-lake enclosures.

Communication skills training for medical residents: Enhancing a psychosocial approach of patient care.

OBJECTIVES: One of the issues that has increasingly become relevant to medical practice is the ability to communicate well with patients. Better communication results in better care for the patient, as well as greater satisfaction for the physician. For this reason, the aim of this study was to assess the efficacy of a communication skills training program for medical residents (MR). METHOD: Eighty-six MR underwent a 6-month training program in three phases: a 12-h theory and practice workshop, a period of real practice, and a 4-h workshop in which the most challenging scenarios were role played with an actress. In each phase (T0, T1, and T2), participants' beliefs about their competence in caring for patients' psychosocial aspects and their self-confidence in communication skills were assessed. RESULTS: No differences were found between T0 and T1 in participants' beliefs of self-competence in psychosocial care. However, this competence significantly improved after completion of the entire program. Only 7 of the 12 areas explored in communication skills significantly improved between T0 and T1. However, after T2 completion, significant improvements were observed in all 12 areas. SIGNIFICANCE OF RESULTS: The research results highlight the usefulness and importance of training young doctors to foster their psychosocial approach to patient care and improve their confidence in their own communication skills. The results also show the appropriateness of the structure of the training: the key features of the programme were the follow-up of the participants in three phases over 6 months, and a focus on the needs of the residents and the resolution of difficult clinical cases, with the support of an actress. Therefore, the training presented in this study may become a guide for other trainings in other contexts with similar objectives.

The CORCOBIA study: Cut-off points of Alzheimer's disease CSF biomarkers in a clinical cohort.

INTRODUCTION: The analysis of the core biomarkers of Alzheimer's Disease (AD) in the cerebrospinal fluid (CSF) is recommended in the clinical units where it is available. Because of the absence of universal validated values, the determination of specific cut-off points for each center and its population is recommended. The main objective of the CORCOBIA study was to determine the cut-off points of core AD CSF biomarkers for several centers (Parc de Salut Mar, Barcelona and Hospital General de Granollers), which work with the same reference laboratory (Laboratori de Referència de Catalunya). METHODS: Prospective study including cognitively unimpaired individuals (CU, n = 42), subjects with amnestic mild cognitive impairment (aMCI, n = 35) and patients with dementia due to Alzheimer's Disease (AD, n = 48), in whom clinical and neuropsychological assessment, neuroimaging, APOE genotyping and lumbar puncture to analyse amyloid beta peptides (Aß42, Aß40), total tau (tTau) and phosphorylated Tau (pTau181) using the Lumipulse G600II (Fujirebio) was performed. The values of sensitivity (SE), specificity (SP), predictive values and area under the curve (AUC) were calculated, determining the cut-off point according to the Youden index by comparing the CU and AD groups. RESULTS: The resulting cut-offs and their AUC were the following: Aß42 750 pg/mL (AUC 0.809); Aß42/Aß40 0.062 (AUC 0.78); pTau181 69.85 pg/mL (AUC 0.81); tTau 522.0 pg/mL (AUC 0.79); Aß42/tTau 1.76 (AUC 0.86); Aß42/pTau181 10.25 (AUC 0.86). CONCLUSIONS: The determination of cut-off points of core AD CSF biomarkers for the participating centers allows a better diagnostic accuracy. The ratio CSF Aß42/pTau181 shows the highest AUC and better balance between sensitivity and specificity.

Plasmodium falciparum Drug Resistance Genes pfmdr1 and pfcrt In Vivo Co-Expression During Artemether-Lumefantrine Therapy.

Background: Artemisinin-based combination therapies (ACTs) are the global mainstay treatment of uncomplicated Plasmodium falciparum infections. PfMDR1 and PfCRT are two transmembrane transporters, associated with sensitivity to several antimalarials, found in the parasite food vacuole. Herein, we explore if their relatedness extends to overlapping patterns of gene transcriptional activity before and during ACT administration. Methods: In a clinical trial performed in Tanzania, we explored the pfmdr1 and pfcrt transcription levels from 48 patients with uncomplicated P. falciparum malaria infections who underwent treatment with artemether-lumefantrine (AL). Samples analyzed were collected before treatment initiation and during the first 24 h of treatment. The frequency of PfMDR1 N86Y and PfCRT K76T was determined through PCR-RFLP or direct amplicon sequencing. Gene expression was analyzed by real-time quantitative PCR. Results: A wide range of pre-treatment expression levels was observed for both genes, approximately 10-fold for pfcrt and 50-fold for pfmdr1. In addition, a significant positive correlation demonstrates pfmdr1 and pfcrt co-expression. After AL treatment initiation, pfmdr1 and pfcrt maintained the positive co-expression correlation, with mild downregulation throughout the 24 h post-treatment. Additionally, a trend was observed for PfMDR1 N86 alleles and higher expression before treatment initiation. Conclusion: pfmdr1 and pfcrt showed significant co-expression patterns in vivo, which were generally maintained during ACT treatment. This observation points to relevant related roles in the normal parasite physiology, which seem essential to be maintained when the parasite is exposed to drug stress. In addition, keeping the simultaneous expression of both transporters might be advantageous for responding to the drug action.

Rat age-related benign prostate hyperplasia is concomitant with an increase in the secretion of low ramified α-glycosydic polysaccharides.

This work analysed the expression of prostate polysaccharides in rats with age-related benign prostatic hyperplasia (BPH) for a better understanding of the possible relationship between prostate polysaccharides secretion and BPH onset. For this, prostatic glands from 1 month-old, 3 months-old, 6 months-old and 12 months-old Sprague-Dawley rats were processed in order to identify their overall polysaccharide content. Additionally, serum testosterone was also determined. One-month old rats showed significantly (P < 0.05) lower testosterone levels (0.77 ng/mL±0.12 ng/mL) compared with the other groups, which showed no significant difference among them. PAS staining showed positive polysaccharides markings in both the prostatic lumen and inside of luminal prostatic cells in all groups. Semiquantitative analysis of intraluminal PAS showed that one month-old rats had significantly (P < 0.005) lower PAS intensity when compared with all other groups (100.0 ± 0.5, arbitrary units vs. 107.3 ± 0.6, arbitrary units in 3 months-old ones), whereas 12 months-old ones showed significantly (P < 0.005) higher values when compared with all other groups (133.6 ± 3.5, arbitrary units in 12 months-old rats vs. 108.6 ± 1.4, arbitrary units in 6 months-old ones). The PAS + content practically disappeared when tissues were pre-incubated with either α-amylase or amyloglucosidase, regardless of a previous incubation with proteinase K. Incubation of prostate extracts from 12 months-old rats for 2 h with α-amylase yielded a significantly higher amount of free glucose (1.47 nmol/mg protein±0.23 nmol/mg protein vs. 0.32 nmol/mg protein±0.01 nmol/mg protein in untreated extracts). Similar results were obtained when extracts were pre-incubated with amyloglucosidase. Contrarily, pre-incubation with N-glycosidase induced a significantly (P < 0.05), much lower increase of free glucose. Pre-treatment with proteinase K did not significantly modify these results, which indicate that BPH is related to an increase in the secretion of low ramified ductal α-glycosydic polysaccharides that were not protected against lysis by any type of protein protective core. These changes seem to not be related with concomitant variations in serum testosterone levels.

The onset of age-related benign prostatic hyperplasia is concomitant with increased serum and prostatic expression of VEGF in rats: Potential role of VEGF as a marker for early prostatic alterations.

The onset of age-related benign prostate hyperplasia (BPH) is linked with changes in the expression of specific prostatic chemokines. The aim of this work was to characterize those most relevant changes through the simultaneous analysis of 34 chemokines in both prostatic tissue and serum in rats at different ages with the aim to identify clinically workable parameters for the detection of early prostatic alterations. The study included 28 healthy Sprague-Dawley male rats that were distributed in four groups, 1 month-old (prepuberal; n = 7), 3 months-old (young; n = 7), 6 months-old (mature; n = 7) and 12 months-old (elder; n = 7). Chemokines were analyzed through a commercial mini-array system specially designed for rat tissues. Serum testosterone levels and prostatic histological status were also evaluated. Histological lesions indicative of BPH were detected in three mature rats and in all elder ones. Mini-arrays from prostatic tissue showed that young animals had an overall decreased expression of most of the analyzed chemokines when compared with prepuberal rats, with the exception of agrin, which showed a significant (P < 0.05) increase (100.0 ± 1.3, arbitrary units in prepuberal rats vs.148.2 ± 4.1, arbitrary units in young ones). Older animals showed further specific changes in 4 out 34 analyzed chemokines, namely agrin, platelet-derived growth factor (PDGF), tissue inhibitor of metalloproteinase-1 (TIMP-1) and vascular endothelial growth factor (VEGF). Additionally, elder rats showed the lowest intensity levels of agrin combined with the highest ones for PDGF, TIMP1 and VEGF when compared with all other groups. Finally, a significant increase of serum VEGF was detected in elder, BPH-affected rats when compared with young ones. Results indicated that the onset of both rat puberty and BPH would be related with specific changes in the prostatic expression of chemokines such as VEGF. Otherwise, the observed changes in serum VEGF levels could suggest the future possible utilization of serum VEGF levels to detect early pathological prostatic processes.

Fate of polycyclic aromatic compounds from diluted bitumen spilled into freshwater limnocorrals.

Diluted bitumens (dilbits) are produced by mixing highly viscous bitumen with lighter petroleum products to facilitate transport. The unique physical and chemical properties of dilbit may affect the environmental fate and effects of dilbit-derived chemical compounds when spilled. To further explore this, we monitored experimental spills of Cold Lake Winter Blend (CLWB) dilbit for 70 days in limnocorrals installed in a freshwater boreal lake. A regression design with 2 controls and 7 treatments was used to assess the fate and behaviour of polycyclic aromatic compounds (PACs) as they partitioned from the dilbit into the air, water column and sediments. Treatments ranged from 1.5 to 180 L of CLWB, resulting in oil:water ratios ranging between 1:71000 to 1:500 (v:v). We began to detect elevated concentrations of PACs as early as 6 h post-addition in the air, 12 h post-addition in the water column, and 15-28 d post-addition in the sediments. By the end of the experiment, concentrations of PACs had largely declined in the water column but remained elevated in the sediments. Our results demonstrate that under conditions typical of temperate boreal lakes, only a small proportion of PACs from dilbit enters the aquatic system, but even so, may produce concentrations of ecotoxicological concern, especially in the sediments, which is the ultimate sink for dilbit-derived PACs.

Thawing Yedoma permafrost is a neglected nitrous oxide source.

In contrast to the well-recognized permafrost carbon (C) feedback to climate change, the fate of permafrost nitrogen (N) after thaw is poorly understood. According to mounting evidence, part of the N liberated from permafrost may be released to the atmosphere as the strong greenhouse gas (GHG) nitrous oxide (N2O). Here, we report post-thaw N2O release from late Pleistocene permafrost deposits called Yedoma, which store a substantial part of permafrost C and N and are highly vulnerable to thaw. While freshly thawed, unvegetated Yedoma in disturbed areas emit little N2O, emissions increase within few years after stabilization, drying and revegetation with grasses to high rates (548 (133-6286) µg N m-2 day-1; median with (range)), exceeding by 1-2 orders of magnitude the typical rates from permafrost-affected soils. Using targeted metagenomics of key N cycling genes, we link the increase in in situ N2O emissions with structural changes of the microbial community responsible for N cycling. Our results highlight the importance of extra N availability from thawing Yedoma permafrost, causing a positive climate feedback from the Arctic in the form of N2O emissions.

Novel nitrogen plasma doping on CdS/GO compounds and their photocatalytic assessment.

Nitrogen-doping of cadmium sulfide nanostructured compounds was carried out under a nitrogen plasma source to produce CdS-N compounds. Once prepared, it was supported on graphene oxide sheets for producing CdS-N/GO photocatalysts, which were tested in the degradation of lignin and methylene blue (MB) molecules. Photocatalytic reactions were carried out under UV and visible (vis) energy irradiation. To provide insight on the catalytic behavior the CdS, CdS-N, GO, and CdS-N/GO compounds were characterized using different techniques including x-ray diffraction, scanning electron microscopy, Raman, and UV-vis diffuse reflectance spectroscopy. X-ray photoelectron spectroscopy allowed determining the chemical composition in samples. It was observed an outstanding performance in photocatalytic activity tests, attributed to the extended response towards the visible light regime, and the synergistic effect between CdS-N and GO particles. The catalytic activity tests, reveal that the CdS-N/GO compound achieved over 90% lignin degradation and 100% of MB degradation. In addition, a remarkable performance is observed in the CdS-N/GO compound which exhibited stability after performing several reaction cycles.

Multilevel selection favors fragmentation modes that maintain cooperative interactions in multispecies communities.

Reproduction is one of the requirements for evolution and a defining feature of life. Yet, across the tree of life, organisms reproduce in many different ways. Groups of cells (e.g., multicellular organisms, colonial microbes, or multispecies biofilms) divide by releasing propagules that can be single-celled or multicellular. What conditions determine the number and size of reproductive propagules? In multicellular organisms, existing theory suggests that single-cell propagules prevent the accumulation of deleterious mutations (e.g., cheaters). However, groups of cells, such as biofilms, sometimes contain multiple metabolically interdependent species. This creates a reproductive dilemma: small daughter groups, which prevent the accumulation of cheaters, are also unlikely to contain the species diversity that is required for ecological success. Here, we developed an individual-based, multilevel selection model to investigate how such multi-species groups can resolve this dilemma. By tracking the dynamics of groups of cells that reproduce by fragmenting into smaller groups, we identified fragmentation modes that can maintain cooperative interactions. We systematically varied the fragmentation mode and calculated the maximum mutation rate that communities can withstand before being driven to extinction by the accumulation of cheaters. We find that for groups consisting of a single species, the optimal fragmentation mode consists of releasing single-cell propagules. For multi-species groups we find various optimal strategies. With migration between groups, single-cell propagules are favored. Without migration, larger propagules sizes are optimal; in this case, group-size dependent fissioning rates can prevent the accumulation of cheaters. Our work shows that multi-species groups can evolve reproductive strategies that allow them to maintain cooperative interactions.

Surface oil is the primary driver of macroinvertebrate impacts following spills of diluted bitumen in freshwater.

The response of freshwater invertebrates following accidental releases of oil is not well understood. This knowledge gap is more substantial for unconventional oils such as diluted bitumen (dilbit). We evaluated the effects of dilbit on insect emergence and benthic invertebrates by conducting experimental spills in limnocorrals (10-m diameter; ~100-m3) deployed in a boreal lake at the IISD-Experimental Lakes Area, Canada. The study included seven dilbit treatments (spill volumes ranged from 1.5 L [1:66,000, oil:water, v/v] to 180 L [1:590, oil:water, v/v]), two controls, and additional lake reference sites, monitored for 11 weeks. Invertebrate emergence declined at the community level following oil addition in a significantly volume-dependent manner, and by 93-100 % over the 11 weeks following the spill in the highest treatment. Dilbit altered community structure of benthic invertebrates, but not abundance. One-year post-spill and following oil removal using traditional skimming and absorption techniques, benthic richness and abundance were greater among all treatments than the previous year. These results indicate that recovery in community composition is possible following oil removal from a lake ecosystem. Research is needed concerning the mechanisms by which surface oil directly affect adult invertebrates, whether through limiting oviposition, limiting emergence, or both. The response of benthic communities to sediment tar mats is also warranted.