Toxicity of inorganic nanoparticles and commercial sunscreens on marine bacteria.

The Balearic Islands, a top tourist destination for sunny beaches, face physical and chemical pressures from human activities, impacting keystone species like the endemic seagrass Posidonia oceanica and its associated microbiome. This study evaluated the effects of ZnO and TiO2 nanoparticles and three commercial sunscreens with varying protection factors (50 or 90) and chemical complexities (1- SPF50_E "eco-friendly"; 2- SPF50 not "eco-friendly"; 3- SPF90 not "eco-friendly") on five heterotrophic bacteria (Pseudomonas azotifigens, Marinobacterium litorale, Thiothrix nivea, Sedimenticola thiotaurini and Cobetia sp) and two autotrophic cyanobacteria (Halothece sp. and Fischerella muscicola) associated to P. oceanica, as well as a natural leaf epiphytic community. Results indicated that TiO2 affected all heterotrophic bacteria, while ZnO was toxic to only two species, while autotrophs were unaffected. Commercial sunscreens impacted three heterotrophs and the natural epiphytic community, while autotrophs were only affected by SPF50. SPF50_E reduced phosphorus uptake, and both SPF50 and SPF90 decreased alkaline phosphatase activity. Reactive oxygen species production was mainly induced by SPF90, followed by SPF50_E and SPF50. Generally, the smallest bacteria were most sensitive to UV-filters (UVFs). This study indicates that UVFs exposure may alter the epiphytic community structure of P. oceanica.

A hotspot of diversity: novel Shewanella species isolated from Baltic Sea sediments delineate a sympatric species complex.

Two bacterial strains, SP1S1-4T and SP2S1-2T, were isolated from sediment samples collected in the Stockholm archipelago in November 2021. Following whole-genome sequencing, these strains were identified as tentatively belonging to two novel Shewanella genospecies, based on digital DNA-DNA hybridization, as implemented in the Type Strain Genome Server. Shewanella septentrionalis, Shewanella baltica and Shewanella hafniensis were, in this order and within a narrow genomic relatedness range, their closest genotypic relatives. Additional sampling and sequencing efforts led to the retrieval of distinct isolates that were monophyletic with SP1S1-4T and SP2S1-2T, respectively, based on phylogenomic analysis of whole-genome sequences. Comparative analyses of genome sequence data, which included blast-based average nucleotide identity, core genome-based and core proteome-based phylogenomics, in addition to MALDI-TOF MS-based protein profiling, confirmed the distinctness of the putative novel genospecies with respect to their closest genotypic relatives. A comprehensive phenotypic characterisation of SP1S1-4T and SP2S1-2T revealed only minor differences with respect to the type strains of S. septentrionalis, S. baltica and S. hafniensis. Based on the collective phylogenomic, proteomic, and phenotypic evidence presented here, we describe two novel genospecies within the genus Shewanella, for which the names Shewanella scandinavica sp. nov. and Shewanella vaxholmensis sp. nov. are proposed. The type strains are, respectively, SP2S1-2T (=CCUG 76457T=CECT 30688T), with a draft genome sequence of 5 041 805 bp and a G+C content of 46.3 mol%, and SP1S1-4T (=CCUG 76453T=CECT 30684T), with a draft genome sequence of 4 920147 bp and a G+C content of 46.0 mol%. Our findings suggest the existence of a species complex formed by the species S. baltica, S. septentrionalis, S. scandinavica sp. nov., and S. vaxholmensis sp. nov., with S. hafniensis falling in the periphery, where distinct genomic species clusters could be identified. However, this does not exclude the possibility of a continuum of genomic diversity within this sedimental ecosystem, as discussed herein with additional sequenced isolates.

Anthracycline-induced cardiovascular toxicity: validation of the Heart Failure Association and International Cardio-Oncology Society risk score.

BACKGROUND AND AIMS: Baseline cardiovascular toxicity risk stratification is critical in cardio-oncology. The Heart Failure Association (HFA) and International Cardio-Oncology Society (ICOS) score aims to assess this risk but lacks real-life validation. This study validates the HFA-ICOS score for anthracycline-induced cardiovascular toxicity. METHODS: Anthracycline-treated patients in the CARDIOTOX registry (NCT02039622) were stratified by the HFA-ICOS score. The primary endpoint was symptomatic or moderate to severe asymptomatic cancer therapy-related cardiac dysfunction (CTRCD), with all-cause mortality and cardiovascular mortality as secondary endpoints. RESULTS: The analysis included 1066 patients (mean age 54 ± 14 years; 81.9% women; 24.5% ≥65 years). According to the HFA-ICOS criteria, 571 patients (53.6%) were classified as low risk, 333 (31.2%) as moderate risk, 152 (14.3%) as high risk, and 10 (0.9%) as very high risk. Median follow-up was 54.8 months (interquartile range 24.6-81.8). A total of 197 patients (18.4%) died, and 718 (67.3%) developed CTRCD (symptomatic: n = 45; moderate to severe asymptomatic: n = 24; and mild asymptomatic: n = 649). Incidence rates of symptomatic or moderate to severe symptomatic CTRCD and all-cause mortality significantly increased with HFA-ICOS score [hazard ratio 28.74, 95% confidence interval (CI) 9.33-88.5; P < .001, and hazard ratio 7.43, 95% CI 3.21-17.2; P < .001) for very high-risk patients. The predictive model demonstrated good calibration (Brier score 0.04, 95% CI 0.03-0.05) and discrimination (area under the curve 0.78, 95% CI 0.70-0.82; Uno's C-statistic 0.78, 95% CI 0.71-0.84) for predicting symptomatic or severe/moderate asymptomatic CTRCD at 12 months. CONCLUSIONS: The HFA-ICOS score effectively categorizes patients by cardiovascular toxicity risk and demonstrates strong predictive ability for high-risk anthracycline-related cardiovascular toxicity and all-cause mortality.

Safety and oncological effectiveness after desensitization in patients with previous hypersensitivity reactions to chemotherapy.

INTRODUCTION: Taxanes and platinum are first-line treatments in gynecological tumors with high rates of hypersensitivity reactions (HSRs), leading to discontinuation of treatment. Desensitization involves induction of temporary tolerance to previously sensitized medications. The aims of this study are to describe HSRs to paclitaxel and carboplatin and evaluate the safety and effectiveness of desensitization protocols in gynecological cancer patients. METHODS: Original, retrospective, descriptive, analytical study, approved by Bioethics and Research Committee, included >18-year-old patients with gynecological tumors experiencing HSRs to first-line chemotherapy. Patients underwent 3-bag-12-step desensitization. RESULTS: 174 desensitization (95 paclitaxel, 79 carboplatin) in 33 female patients, mean age 45.5 years (18-71y). Cancer diagnosis: breast 8 (24.2%), ovarian 14 (42.2%), endometrial 2 (6.1%) and cervix 9 (27.2%). HSR occurred in paclitaxel during cycles 1-2 and in carboplatin after 6 cycles. The most frequently seen HSR symptom was cardiovascular with paclitaxel (94.7%), and cutaneous (93.3%) with carboplatin. Three-bags 12-steps desensitization protocol (initial dilution 1:100) in 5.67hrs. All patients reached total dose desensitization: 82% with no reaction, 12% mild, 6% moderate and 0% severe reaction. Mean disease-free interval and progression-free interval in months (m): breast cancer 29 m and 14 m, ovarian 22 m and 9 m, endometrial 40 m and cervical cancer: 67.5 m and 27 m. Twenty-five patients (73.5%) are still alive. CONCLUSION: HSRs to paclitaxel manifest in the first 1-2 cycles and to carboplatin after 6 cycles. Symptoms include cardiovascular, atypical neuromuscular and urticaria. Changing treatment lines impacts prognosis. Our study revealed that ovarian cancer patients undergoing desensitization protocols achieved longer progression-free intervals. All patients successfully reached total dose desensitization. This study provides evidence of the effectiveness and safety of desensitization and promising perspective for continuing first-line treatment with HSRs.

Nitrogen Fixation and Microbial Communities Associated with Decomposing Seagrass Leaves in Temperate Coastal Waters.

Seagrass meadows play pivotal roles in coastal biochemical cycles, with nitrogen fixation being a well-established process associated with living seagrass. Here, we tested the hypothesis that nitrogen fixation is also associated with seagrass debris in Danish coastal waters. We conducted a 52-day in situ experiment to investigate nitrogen fixation (proxied by acetylene reduction) and dynamics of the microbial community (16S rRNA gene amplicon sequencing) and the nitrogen fixing community (nifH DNA/RNA amplicon sequencing) associated with decomposing Zostera marina leaves. The leaves harboured distinct microbial communities, including distinct nitrogen fixers, relative to the surrounding seawater and sediment throughout the experiment. Nitrogen fixation rates were measurable on most days, but highest on days 3 (dark, 334.8 nmol N g-1 dw h-1) and 15 (light, 194.6 nmol N g-1 dw h-1). Nitrogen fixation rates were not correlated with the concentration of inorganic nutrients in the surrounding seawater or with carbon:nitrogen ratios in the leaves. The composition of nitrogen fixers shifted from cyanobacterial Sphaerospermopsis to heterotrophic genera like Desulfopila over the decomposition period. On the days with highest fixation, nifH RNA gene transcripts were mainly accounted for by cyanobacteria, in particular by Sphaerospermopsis and an unknown taxon (order Nostocales), alongside Proteobacteria. Our study shows that seagrass debris in temperate coastal waters harbours substantial nitrogen fixation carried out by cyanobacteria and heterotrophic bacteria that are distinct relative to the surrounding seawater and sediments. This suggests that seagrass debris constitutes a selective environment where degradation is affected by the import of nitrogen via nitrogen fixation.

Litsea glaucescens Kuth possesses bactericidal activity against Listeria monocytogenes.

Background: Litsea glaucencens Kuth is an aromatic plant used for food seasoning food and in Mexican traditional medicine. Among, L. glaucencens leaves properties, it has proven antibacterial activity which can be used against opportunistic pathogens like Listeria monocytogenes, a foodborne bacteria that is the causal agent of listeriosis, a disease that can be fatal in susceptible individuals. The aim of this work was to investigate the antibacterial activity of L. glaucescens Kuth leaf extracts against L. monocytogenes and to identify its bioactive components. Material and Methods: L. glaucences leaves were macerated with four solvents of different polarity (n-hexane, dichloromethane, ethyl acetate, and methanol). To determine the capacity to inhibit bacterial proliferation in vitro, agar diffusion and microdilution methods were used. Next, we determined the minimal bactericidal concentration (MBC). Finally, we determined the ratio of MBC/MIC. Metabolites present in the active methanolic extract from L. glaucescens Kuth (LgMeOH) were purified by normal-phase open column chromatography. The structure of the antibacterial metabolite was determined using nuclear magnetic resonance (1H, 13C, COSY, HSQC) and by comparison with known compounds. Results: The LgMeOH extract was used to purify the compound responsible for the observed antimicrobial activity. This compound was identified as 5,7-dihydroxyflavanone (pinocembrin) by analysis of its spectroscopic data and comparison with those described. The MIC and MBC values obtained for pinocembrin were 0.68 mg/mL, and the ratio MBC/MIC for both LgMeOH and pinocembrin was one, which indicates bactericidal activity. Conclusion: L. glaucences Kuth leaves and its metabolite pinocembrin can be used to treat listeriosis due the bactericidal activity against L. monocytogenes.

Current research trends on cognition, integrative complexity, and decision-making: a systematic literature review using activity theory and neuroscience.

Introduction: This article presents a systematic literature review that follows the PRISMA and PICOS guidelines to analyze current research trends on cognition, integrative complexity (IC) (a cognitive feature focusing on information processing in a person's response rather than its quantity or quality), and decision-making from the perspectives of activity theory and neuroscience. Methods: The study examines 31 papers published between 2012 and 2022 and 19 articles specifically related to neuroscience. We performed a content analysis using six categories within activity theory: subjects, objects, rules, community, division of labor, and outcomes. Results: The study investigates the relationship between decision-making outcomes and IC as a cognitive feature in various contexts. Additionally, content analysis on neuroscience and IC revealed significant research gaps, including understanding the nature of IC, challenges related to its measurement, and differentiation from other cognitive features. We also identify opportunities for investigating the brain's activity during decision-making in relation to IC. Discussion: We address the need for a more precise categorization of IC in studies of cognition, IC, and decision-making. We discuss the implications of our analysis for understanding the cognitive nature of IC and the potential of neuroscience methods for studying this attribute.

Biofilm formation and cell plasticity drive diazotrophy in an anoxygenic phototrophic bacterium.

IMPORTANCE: The contribution of non-cyanobacterial diazotrophs (NCDs) to total N2 fixation in the marine water column is unknown, but their importance is likely constrained by the limited availability of dissolved organic matter and low O2 conditions. Light could support N2 fixation and growth by NCDs, yet no examples from bacterioplankton exist. In this study, we show that the phototrophic NCD, Rhodopseudomonas sp. BAL398, which is a member of the diazotrophic community in the surface waters of the Baltic Sea, can utilize light. Our study highlights the significance of biofilm formation for utilizing light and fixing N2 under oxic conditions and the role of cell plasticity in regulating these processes. Our findings have implications for the general understanding of the ecology and importance of NCDs in marine waters.

Comparative genomics of Stutzerimonas balearica (Pseudomonas balearica): diversity, habitats, and biodegradation of aromatic compounds.

Stutzerimonas balearica (Pseudomonas balearica) has been found principally in oil-polluted environments. The capability of S. balearica to thrive from the degradation of pollutant compounds makes it a species of interest for potential bioremediation applications. However, little has been reported about the diversity of S. balearica. In this study, genome sequences of S. balearica strains from different origins were analyzed, revealing that it is a diverse species with an open pan-genome that will continue revealing new genes and functionalities as the genomes of more strains are sequenced. The nucleotide signatures and intra- and inter-species variation of the 16S rRNA genes of S. balearica were reevaluated. A strategy of screening 16S rRNA gene sequences in public databases enabled the detection of 158 additional strains, of which only 23% were described as S. balearica. The species was detected from a wide range of environments, although mostly from aquatic and polluted environments, predominantly related to petroleum oil. Genomic and phenotypic analyses confirmed that S. balearica possesses varied inherent capabilities for aromatic compounds degradation. This study increases the knowledge of the biology and diversity of S. balearica and will serve as a basis for future work with the species.

Legionella maioricensis sp. nov., a new species isolated from the hot water distribution systems of a hospital and a shopping center during routine sampling.

Two Legionella-like strains isolated from hot water distribution systems in 2012 have been characterized phenotypically, biochemically and genomically in terms of DNA relatedness. Both strains, HCPI-6T and EUR-108, exhibited biochemical phenotypic profiles typical of Legionella species. Cells were Gram-negative motile rods which grew on BCYEα agar but not on blood agar and displayed phenotypic characteristics typical of the family Legionellaceae, including a requirement for l-cysteine and testing catalase positive. Both strains were negative for oxidase, urease, nitrate reduction and hippurate negative, and non-fermentative. The major ubiquinone was Q12 (59.4 % HCPI-6T) and the dominant fatty acids were C16 : 1 ω7c (28.4 % HCPI-6T, ≈16 % EUR-108), C16 : 0 iso (≈22.5 % and ≈13 %) and C15 : 0 anteiso (19.5 % and ≈23.5 %, respectively). The percent G+C content of genomic DNA was determined to be 39.3 mol %. The 16S rRNA gene, mip sequence and comparative genome sequence-based analyses (average nucleotide identity, ANI; digital DNA-DNA hybridization, dDDH; and phylogenomic treeing) demonstrated that the strains represent a new species of the genus Legionella. The analysis based on the 16S rRNA gene sequences showed that the sequence similarities for both strains ranged from 98.8-90.1 % to other members of the genus. The core genome-based phylogenomic tree (protein-concatemer tree based on concatenation of 418 proteins present in single copy) revealed that these two strains clearly form a separate cluster within the genus Legionella. ANI and dDDH values confirmed the distinctiveness of the strains. Based on the genomic, genotypic and phenotypic findings from a polyphasic study, the isolates are considered to represent a single novel species, for which the name Legionella maioricensis sp. nov. is proposed. The type strain is HCPI-6T (=CCUG 75071T=CECT 30569T).

Challenges in the Detection of SARS-CoV-2: Evolution of the Lateral Flow Immunoassay as a Valuable Tool for Viral Diagnosis.

SARS-CoV-2 is an emerging infectious disease of zoonotic origin that caused the coronavirus disease in late 2019 and triggered a pandemic that has severely affected human health and caused millions of deaths. Early and massive diagnosis of SARS-CoV-2 infected patients is the key to preventing the spread of the virus and controlling the outbreak. Lateral flow immunoassays (LFIA) are the simplest biosensors. These devices are clinical diagnostic tools that can detect various analytes, including viruses and antibodies, with high sensitivity and specificity. This review summarizes the advantages, limitations, and evolution of LFIA during the SARS-CoV-2 pandemic and the challenges of improving these diagnostic devices.

Everything Is Everywhere: Physiological Responses of the Mediterranean Sea and Eastern Pacific Ocean Epiphyte Cobetia Sp. to Varying Nutrient Concentration.

Bacteria are essential in the maintenance and sustainment of marine environments (e.g., benthic systems), playing a key role in marine food webs and nutrient cycling. These microorganisms can live associated as epiphytic or endophytic populations with superior organisms with valuable ecological functions, e.g., seagrasses. Here, we isolated, identified, sequenced, and exposed two strains of the same species (i.e., identified as Cobetia sp.) from two different marine environments to different nutrient regimes using batch cultures: (1) Cobetia sp. UIB 001 from the endemic Mediterranean seagrass Posidonia oceanica and (2) Cobetia sp. 4B UA from the endemic Humboldt Current System (HCS) seagrass Heterozostera chilensis. From our physiological studies, both strains behaved as bacteria capable to cope with different nutrient and pH regimes, i.e., N, P, and Fe combined with different pH levels, both in long-term (12 days (d)) and short-term studies (4 d/96 h (h)). We showed that the isolated strains were sensitive to the N source (inorganic and organic) at low and high concentrations and low pH levels. Low availability of phosphorus (P) and Fe had a negative independent effect on growth, especially in the long-term studies. The strain UIB 001 showed a better adaptation to low nutrient concentrations, being a potential N2-fixer, reaching higher growth rates (µ) than the HCS strain. P-acquisition mechanisms were deeply investigated at the enzymatic (i.e., alkaline phosphatase activity, APA) and structural level (e.g., alkaline phosphatase D, PhoD). Finally, these results were complemented with the study of biochemical markers, i.e., reactive oxygen species (ROS). In short, we present how ecological niches (i.e., MS and HCS) might determine, select, and modify the genomic and phenotypic features of the same bacterial species (i.e., Cobetia spp.) found in different marine environments, pointing to a direct correlation between adaptability and oligotrophy of seawater.

Cell size matters: Nano- and micro-plastics preferentially drive declines of large marine phytoplankton due to co-aggregation.

Marine plastic pollution represents a key environmental concern. Whilst ecotoxicological data for plastic is increasingly available, its impact upon marine phytoplankton remains unclear. Owing to their predicted abundance in the marine environment and likely interactions with phytoplankton, here we focus on the smaller fraction of plastic particles (~50 nm and ~2 µm polystyrene spheres). Exposure of natural phytoplankton communities and laboratory cultures revealed that plastic exposure does not follow traditional trends in ecotoxicological research, since large phytoplankton appear particularly susceptible towards plastics exposure despite their lower surface-to-volume ratios. Cell declines appear driven by hetero-aggregation and co-sedimentation of cells with plastic particles, recorded visually and demonstrated using confocal microscopy. As a consequence, plastic exposure also caused disruption to photosynthetic functioning, as determined by both photosynthetic efficiency and high throughput proteomics. Negative effects upon phytoplankton are recorded at concentrations orders of magnitude above those estimated in the environment. Hence, it is likely that impacts of NPs and MPs are exacerbated at the high concentrations typically used in ecotoxicological research (i.e., mg L-1).

Pectin-gellan films intended for active food packaging: release kinetics of nisin and physico-mechanical characterization.

Films were prepared by casting 2% w/v apple pectin, 0.5% w/v low-acyl gellan and 2.2% w/v glycerol as plasticizer. Bioactive film (BF, films with 3912 International Units (IU) nisin/cm2) and control films (CF, films without nisin) were elaborated. The objective was to analyze the release kinetics of nisin from films to a food model, to determine the period of film bioactivity and potential use as antimicrobial packaging. The release of nisin from BF to a food model was determined at 5 °C and 30 °C. The release kinetics of nisin was fitted to the analytical solution of the Fick's second law for an infinite plate. The diffusion coefficients of nisin (D) were 5.22 × 10-14 and 7.36 × 10-14 m2/s for 5 °C and 30 °C, respectively. Besides, both films were characterized in their mechanical properties and gas permeabilities [oxygen (PO2) and water vapour permeability (WVP)]. The mechanical properties were reduced by the nisin incorporation, whereas PO2 was increased, and no significant effect on WVP was observed.

Nivolumab plus Cabozantinib versus Sunitinib for Advanced Renal-Cell Carcinoma.

BACKGROUND: The efficacy and safety of nivolumab plus cabozantinib as compared with those of sunitinib in the treatment of previously untreated advanced renal-cell carcinoma are not known. METHODS: In this phase 3, randomized, open-label trial, we randomly assigned adults with previously untreated clear-cell, advanced renal-cell carcinoma to receive either nivolumab (240 mg every 2 weeks) plus cabozantinib (40 mg once daily) or sunitinib (50 mg once daily for 4 weeks of each 6-week cycle). The primary end point was progression-free survival, as determined by blinded independent central review. Secondary end points included overall survival, objective response as determined by independent review, and safety. Health-related quality of life was an exploratory end point. RESULTS: Overall, 651 patients were assigned to receive nivolumab plus cabozantinib (323 patients) or sunitinib (328 patients). At a median follow-up of 18.1 months for overall survival, the median progression-free survival was 16.6 months (95% confidence interval [CI], 12.5 to 24.9) with nivolumab plus cabozantinib and 8.3 months (95% CI, 7.0 to 9.7) with sunitinib (hazard ratio for disease progression or death, 0.51; 95% CI, 0.41 to 0.64; P<0.001). The probability of overall survival at 12 months was 85.7% (95% CI, 81.3 to 89.1) with nivolumab plus cabozantinib and 75.6% (95% CI, 70.5 to 80.0) with sunitinib (hazard ratio for death, 0.60; 98.89% CI, 0.40 to 0.89; P = 0.001). An objective response occurred in 55.7% of the patients receiving nivolumab plus cabozantinib and in 27.1% of those receiving sunitinib (P<0.001). Efficacy benefits with nivolumab plus cabozantinib were consistent across subgroups. Adverse events of any cause of grade 3 or higher occurred in 75.3% of the 320 patients receiving nivolumab plus cabozantinib and in 70.6% of the 320 patients receiving sunitinib. Overall, 19.7% of the patients in the combination group discontinued at least one of the trial drugs owing to adverse events, and 5.6% discontinued both. Patients reported better health-related quality of life with nivolumab plus cabozantinib than with sunitinib. CONCLUSIONS: Nivolumab plus cabozantinib had significant benefits over sunitinib with respect to progression-free survival, overall survival, and likelihood of response in patients with previously untreated advanced renal-cell carcinoma. (Funded by Bristol Myers Squibb and others; CheckMate 9ER ClinicalTrials.gov number, NCT03141177.).

Helminths of the Wild Boar (Sus scrofa) from Units of Conservation Management and Sustainable Use of Wildlife Installed in the Eastern Economic Region of Mexico.

Wild boars (Sus scrofa) were introduced in Mexico for sport hunting and meat trading for human consumption, but the available data regarding their role in pathogen transmission are limited. This research and field work aimed to identify the helminths of the wild boar produced in three units of conservation management and sustainable use of wildlife placed in the eastern economic region of Mexico. Samples of feces and serum were collected from 90 animals that came from three different ranches. Stool examination and antibody determination to Fasciola hepatica, Taenia crassciceps, Ascaris suum, Toxocara canis (ELISA), and Trichinella spiralis (Western blot) were performed. In addition, 30 diaphragm samples from one ranch were obtained for artificial digestion. Eggs of Strongyloides sp. (72.2%), Metastrongylus sp. (57.7%), Oesophagostomum sp. (53.3%), and Trichuris sp. (37.7%) were found in addition to oocysts of Eimeria sp. (75.6%). Antibodies to Fasciola (8.9%), Taenia (4.4%), Ascaris (32.2%), Toxocara (20%), and Trichinella (5.5%) were found. The eggs of Strongyloides and Oesophagostomum were associated to female hosts. One nematode larva was found by artificial digestion. This is the first report to identify helminths from wild boars in Mexico. In addition, this study identifies the potential risk of the wild boar as a transmission channel of parasites that can have an impact on public health.

Differential Effects of Varying Concentrations of Phosphorus, Iron, and Nitrogen in N2-Fixing Cyanobacteria.

Diazotrophs or N2-fixers are one of the most ecologically significant groups in marine ecosystems (pelagic and benthic). Inorganic phosphorus (PO4 3-) and iron (Fe) can limit the growth and N2-fixing capacities of cyanobacteria. However, studies investigating co-limitation of these factors are lacking. Here, we added different concentrations of PO4 3- and Fe in two cyanobacterial species whose relatives can be found in seagrass habitats: the unicellular Halothece sp. (PCC 7418) and the filamentous Fischerella muscicola (PCC 73103), grown under different nitrate (NO3 -) concentrations and under N2 as sole N source, respectively. Their growth, pigment content, N2-fixation rates, oxidative stress responses, and morphological and cellular changes were investigated. Our results show a serial limitation of NO3 - and PO4 3- (with NO3 - as the primary limiting nutrient) for Halothece sp. Simultaneous co-limitation of PO4 3- and Fe was found for both species tested, and high levels of Fe (especially when added with high PO4 3- levels) inhibited the growth of Halothece sp. Nutrient limitation (PO4 3-, Fe, and/or NO3 -) enhanced oxidative stress responses, morphological changes, and apoptosis. Furthermore, an extensive bio-informatic analysis describing the predicted Pho, Fur, and NtcA regulons (involved in the survival of cells to P, Fe, and N limitation) was made using the complete genome of Halothece sp. as a model, showing the potential of this strain to adapt to different nutrient regimes (P, Fe, or N).

Calculation of the EPR g-tensor from auxiliary density functional theory.

The working equations for the calculation of the electron paramagnetic resonance (EPR) g-tensor within the framework of the auxiliary density functional theory (ADFT) are presented. The scheme known as gauge including atomic orbitals (GIAOs) is employed to treat the gauge origin problem. This ADFT-GIAO formulation possesses an inherent high computational performance, allowing for the calculation of the EPR g-tensor of molecules containing some hundreds of atoms in reasonable computational time employing moderate computational resources. The effect of the use of a gauge independent auxiliary density on the quality of the g-tensor calculation for the evaluation of the exchange-correlation contribution is analyzed in this work. The best agreement with the experiment is obtained with the BLYP functional (Becke 1988 exchange and Lee-Yang-Parr correlation) in combination with a double-ζ basis set, in particular aug-cc-pVDZ. Furthermore, models of endohedral fullerenes N@Cn, with n = {60, 70, 100, 180, 240}, were used for benchmarking its computational performance.

"The Good, the Bad and the Double-Sword" Effects of Microplastics and Their Organic Additives in Marine Bacteria.

Little is known about the direct effects of microplastics (MPs) and their organic additives on marine bacteria, considering their role in the nutrient cycles, e.g., N-cycles through the N2-fixation, or in the microbial food web. To fill this gap of knowledge, we exposed marine bacteria, specifically diazotrophs, to pure MPs which differ in physical properties (e.g., density, hydrophobicity, and/or size), namely, polyethylene, polypropylene, polyvinyl chloride and polystyrene, and to their most abundant associated organic additives (e.g., fluoranthene, 1,2,5,6,9,10-hexabromocyclododecane and dioctyl-phthalate). Growth, protein overproduction, direct physical interactions between MPs and bacteria, phosphorus acquisition mechanisms and/or N2-fixation rates were evaluated. Cyanobacteria were positively affected by environmental and high concentrations of MPs, as opposed to heterotrophic strains, that were only positively affected with high concentrations of ~120 µm-size MPs (detecting the overproduction of proteins related to plastic degradation and C-transport), and negatively affected by 1 µm-size PS beads. Generally, the organic additives had a deleterious effect in both autotrophic and heterotrophic bacteria and the magnitude of the effect is suggested to be dependent on bacterial size. Our results show species-specific responses of the autotrophic and heterotrophic bacteria tested and the responses (beneficial: the "good," deleterious: the "bad" and/or both: the "double-sword") were dependent on the type and concentration of MPs and additives. This suggests the need to determine the threshold levels of MPs and additives concentrations starting from which significant effects can be observed for key microbial populations in marine systems, and these data are necessary for effective environmental quality control management.

Hydrolyzed Collagen-Sources and Applications.

Hydrolyzed collagen (HC) is a group of peptides with low molecular weight (3-6 KDa) that can be obtained by enzymatic action in acid or alkaline media at a specific incubation temperature. HC can be extracted from different sources such as bovine or porcine. These sources have presented health limitations in the last years. Recently research has shown good properties of the HC found in skin, scale, and bones from marine sources. Type and source of extraction are the main factors that affect HC properties, such as molecular weight of the peptide chain, solubility, and functional activity. HC is widely used in several industries including food, pharmaceutical, cosmetic, biomedical, and leather industries. The present review presents the different types of HC, sources of extraction, and their applications as a biomaterial.