Participation of the spleen in the neuroinflammation after pilocarpine-induced status epilepticus: implications for epileptogenesis and epilepsy

Epilepsy, a chronic neurological disorder characterized by recurrent seizures, affects millions of individuals worldwide. Despite extensive research, the underlying mechanisms leading to epileptogenesis, the process by which a normal brain develops epilepsy, remain elusive. We, here, explored the immune system and spleen responses triggered by pilocarpine-induced status epilepticus (SE) focusing on their role in the epileptogenesis that follows SE. Initial examination of spleen histopathology revealed transient disorganization of white pulp, in animals subjected to SE. This disorganization, attributed to immune activation, peaked at 1-day post-SE (1DPSE) but returned to control levels at 3DPSE. Alterations in peripheral blood lymphocyte populations, demonstrated a decrease following SE, accompanied by a reduction in CD3+ T-lymphocytes. Further investigations uncovered an increased abundance of T-lymphocytes in the piriform cortex and choroid plexus at 3DPSE, suggesting a specific mobilization toward the Central Nervous System. Notably, splenectomy mitigated brain reactive astrogliosis, neuroinflammation, and macrophage infiltration post-SE, particularly in the hippocampus and piriform cortex. Additionally, splenectomized animals exhibited reduced lymphatic follicle size in the deep cervical lymph nodes. Most significantly, splenectomy correlated with improved neuronal survival, substantiated by decreased neuronal loss and reduced degenerating neurons in the piriform cortex and hippocampal CA2-3 post-SE. Overall, these findings underscore the pivotal role of the spleen in orchestrating immune responses and neuroinflammation following pilocarpine-induced SE, implicating the peripheral immune system as a potential therapeutic target for mitigating neuronal degeneration in epilepsy.

Improving motor imagery through a mirror box for BCI users

The aim of this study was to evaluate mirror visual feedback (MVF) as a training tool for brain-computer interface (BCI) users. This is because approximately 20-30% of subjects require more training to operate a BCI system using motor imagery. Electroencephalograms (EEGs) were recorded from 18 healthy subjects, using event-related desynchronization (ERD) to observe the responses during the movement or movement intention of the hand for the conditions of control, imagination, and the MVF with the mirror box. We constituted two groups: group 1: control, imagination, and MVF; group 2: control, MVF, and imagination. There were significant differences in imagination conditions between groups using MVF before or after imagination (right-hand, P = 0.0403; left-hand, P = 0.00939). The illusion of movement through MVF is not possible in all subjects, but even in those cases, we found an increase in imagination when the subject used the MVF previously. The increase in the r2s of imagination in the right and left hands suggests cross-learning. The increase in motor imagery recorded with EEG after MVF suggests that the mirror box made it easier to imagine movements. Our results provide evidence that the MVF could be used as a training tool to improve motor imagery.NEW & NOTEWORTHY The increase in motor imagery recorded with EEG after MVF (mirror visual feedback) suggests that the mirror box made it easier to imagine movements. Our results demonstrate that MVF could be used as a training tool to improve motor imagery.

Engineering a nanoantibiotic system displaying dual mechanism of action

In recent decades, peptide amphiphiles (PAs) have established themselves as promising self-assembling bioinspired materials in a wide range of medical fields. Herein, we report a dual-therapeutic system constituted by an antimicrobial PA and a cylindrical protease inhibitor (LJC) to achieve broad antimicrobial spectrum and to enhance therapeutic efficacy. We studied two strategies: PA-LJC nanostructures (Encapsulation) and PA nanostructures + free LJC (Combination). Computational modeling using a molecular theory for amphiphile self-assembly captures and explains the morphology of PA-LJC nanostructures and the location of encapsulated LJC in agreement with transmission electron microscopy and two-dimensional (2D) NMR observations. The morphology and release profile of PA-LJC assemblies are strongly correlated to the PA:LJC ratio: high LJC loading induces an initial burst release. We then evaluated the antimicrobial activity of our nanosystems toward gram-positive and gram-negative bacteria. We found that the Combination broadens the spectrum of LJC, reduces the therapeutic concentrations of both agents, and is not impacted by the inoculum effect. Further, the Encapsulation provides additional benefits including bypassing water solubility limitations of LJC and modulating the release of this molecule. The different properties of PA-LJC nanostructures results in different killing profiles, and reduced cytotoxicity and hemolytic activity. Meanwhile, details in membrane alterations caused by each strategy were revealed by various microscopy and fluorescent techniques. Last, in vivo studies in larvae treated by the Encapsulation strategy showed better antimicrobial efficacy than polymyxin B. Collectively, this study established a multifunctional platform using a versatile PA to act as an antibiotic, membrane-penetrating assistant, and slow-release delivery vehicle.

First biochemical and behavioural analysis of the response of the scorpion Urophonius brachycentrus (Thorell: 1876) upon exposure to an organophosphate

Scorpionism is an increasing public health problem in the world. Although no specific methodology or product is currently available for the control of those arachnids, the use of insecticides could be an effective tool. Chlorpyrifos is one of the insecticides used, but to date, whether scorpions recognise surfaces with that insecticide and how it affects their physiology and/or biochemistry is unknown. In the present study, we observed that scorpions recognise surfaces with 0.51 and 8.59 μg/cm2 of chlorpyrifos and avoid those areas. The 0.51 μg/cm2 concentration produced a decrease in acetylcholinesterase and an increase in catalase, superoxide dismutase and glutathione S-transferase, whereas the 8.59 μg/cm2 concentration evoked a decrease in acetylcholinesterase and an increase in catalase and glutathione S-transferase. Using the comet assay, we observed that the insecticide at 0.17, 0.51 and 8.59 μg/cm2 caused DNA damage. Finally, we found that the insecticide does not generate significant variations in glutathione peroxidase, glutathione reductase, the amount of protein or lipid peroxidation. The present results offer a comprehensive understanding of how scorpions respond, both at the biochemical and behavioural levels, when exposed to insecticides.

Genomic epidemiology of third-generation cephalosporin-resistant Escherichia coli from Argentinian pig and dairy farms reveals animal-specific patterns of co-resistance and resistance mechanisms

Control measures are being introduced globally to reduce the prevalence of antibiotic resistance (ABR) in bacteria on farms. However, little is known about the current prevalence and molecular ecology of ABR in bacterial species with the potential to be key opportunistic human pathogens, such as Escherichia coli, on South American farms. Working with 30 dairy cattle farms and 40 pig farms across two provinces in central-eastern Argentina, we report a comprehensive genomic analysis of third-generation cephalosporin-resistant (3GC-R) E. coli, which were recovered from 34.8% (cattle) and 47.8% (pigs) of samples from fecally contaminated sites. Phylogenetic analysis revealed substantial diversity suggestive of long-term horizontal and vertical transmission of 3GC-R mechanisms. CTX-M-15 and CTX-M-2 were more often produced by isolates from dairy farms, while CTX-M-8 and CMY-2 and co-carriage of amoxicillin/clavulanate resistance and florfenicol resistance were more common in isolates from pig farms. This suggests different selective pressures for antibiotic use in these two animal types. We identified the β-lactamase gene blaROB, which has previously only been reported in the family Pasteurellaceae, in 3GC-R E. coli. blaROB was found alongside a novel florfenicol resistance gene, ydhC, also mobilized from a pig pathogen as part of a new composite transposon. As the first comprehensive genomic survey of 3GC-R E. coli in Argentina, these data set a baseline from which to measure the effects of interventions aimed at reducing on-farm ABR and provide an opportunity to investigate the zoonotic transmission of resistant bacteria in this region.

IMPORTANCE

Little is known about the ecology of critically important antibiotic resistance among bacteria with the potential to be opportunistic human pathogens (e.g., Escherichia coli) on South American farms. By studying 70 pig and dairy cattle farms in central-eastern Argentina, we identified that third-generation cephalosporin resistance (3GC-R) in E. coli was mediated by mechanisms seen more often in certain species and that 3GC-R pig E. coli were more likely to be co-resistant to florfenicol and amoxicillin/clavulanate. This suggests that on-farm antibiotic usage is key to selecting the types of E. coli present on these farms. 3GC-R E. coli and 3GC-R plasmids were diverse, suggestive of long-term circulation in this region. We identified the de novo mobilization of the resistance gene blaROB from pig pathogens into E. coli on a novel mobile genetic element, which shows the importance of surveying poorly studied regions for antibiotic resistance that might impact human health.

Draft genome sequence of Mannheimia haemolytica strain Oliden, isolated from a calf lung infection in Argentina

We present the draft genome sequence of a Mannheimia haemolytica strain isolated from a postmortem lung lesion from a calf diagnosed with bovine respiratory disease. The genome sequence was 2,749,707-bp long with 2,909 putative protein-encoding genes.

Genetic dissection of the degradation pathways for the mycotoxin fusaric acid in Burkholderia ambifaria T16

IMPORTANCE

Fusaric acid (FA) is an important virulence factor produced by several Fusarium species. These fungi are responsible for wilt and rot diseases in a diverse range of crops. FA is toxic for animals, humans and soil-borne microorganisms. This mycotoxin reduces the survival and competition abilities of bacterial species able to antagonize Fusarium spp., due to its negative effects on viability and the production of antibiotics effective against these fungi. FA biodegradation is not a common characteristic among bacteria, and the determinants of FA catabolism have not been identified so far in any microorganism. In this study, we identified genes, enzymes, and metabolic pathways involved in the degradation of FA in the soil bacterium Burkholderia ambifaria T16. Our results provide insights into the catabolism of a pyridine-derivative involved in plant pathogenesis by a rhizosphere bacterium.

Long noncoding RNA-mediated epigenetic regulation of auxin-related genes controls shade avoidance syndrome in Arabidopsis

The long noncoding RNA (lncRNA) AUXIN-REGULATED PROMOTER LOOP (APOLO) recognizes a subset of target loci across the Arabidopsis thaliana genome by forming RNA-DNA hybrids (R-loops) and modulating local three-dimensional chromatin conformation. Here, we show that APOLO regulates shade avoidance syndrome by dynamically modulating expression of key factors. In response to far-red (FR) light, expression of APOLO anti-correlates with that of its target BRANCHED1 (BRC1), a master regulator of shoot branching in Arabidopsis thaliana. APOLO deregulation results in BRC1 transcriptional repression and an increase in the number of branches. Accumulation of APOLO transcription fine-tunes the formation of a repressive chromatin loop encompassing the BRC1 promoter, which normally occurs only in leaves and in a late response to far-red light treatment in axillary buds. In addition, our data reveal that APOLO participates in leaf hyponasty, in agreement with its previously reported role in the control of auxin homeostasis through direct modulation of auxin synthesis gene YUCCA2, and auxin efflux genes PID and WAG2. We show that direct application of APOLO RNA to leaves results in a rapid increase in auxin signaling that is associated with changes in the plant response to far-red light. Collectively, our data support the view that lncRNAs coordinate shade avoidance syndrome in A. thaliana, and reveal their potential as exogenous bioactive molecules. Deploying exogenous RNAs that modulate plant-environment interactions may therefore become a new tool for sustainable agriculture.

Paternal age and risk for selected birth defects in a large South American sample

BACKGROUND

The relationship between maternal age (MA) and birth defects (BD) has been extensively studied while much less research, mostly with discordant results, has focused on the risk of paternal age (PA) for BD. Furthermore, no consensus has been reached on the best way to control the association of PA with MA.

OBJECTIVES

The aim of the study was to evaluate the risk of PA increase, at 1-year intervals, for selected BD, especially controlling for the confounding effect of MA.

METHODS

The sample comprised of 27,944 liveborns presenting 1 of 18 selected isolated BD. Conditional logistic regressions were applied to evaluate the risk of advanced PA and its yearly increase, adjusting by MA and other variables.

RESULTS

Of the 18 analyzed BD, only the risk for preaxial polydactyly (PreP) showed a significant association with increasing PA, while advanced MA was of low risk. For esophageal and anal atresia, associations with both PA and MA increases were observed.

CONCLUSIONS

Results support the hypothesis of advanced PA as a risk factor for PreP and helps clarify the so far unexplained nonrandom association between this defect and Down syndrome.

Identification and characterization of novel alphacoronaviruses in Tadarida brasiliensis (Chiroptera, Molossidae) from Argentina: insights into recombination as a mechanism favoring bat coronavirus cross-species transmission

Bats are reservoirs of various coronaviruses that can jump between bat species or other mammalian hosts, including humans. This article explores coronavirus infection in three bat species (Tadarida brasiliensis, Eumops bonariensis, and Molossus molossus) of the family Molossidae from Argentina using whole viral metagenome analysis. Fecal samples of 47 bats from three semiurban or highly urbanized areas of the province of Santa Fe were investigated. After viral particle enrichment, total RNA was sequenced using the Illumina NextSeq 550 instrument; the reads were assembled into contigs and taxonomically and phylogenetically analyzed. Three novel complete Alphacoronavirus (AlphaCoV) genomes (Tb1-3) and two partial sequences were identified in T. brasiliensis (Tb4-5), and an additional four partial sequences were identified in M. molossus (Mm1-4). Phylogenomic analysis showed that the novel AlphaCoV clustered in two different lineages distinct from the 15 officially recognized AlphaCoV subgenera. Tb2 and Tb3 isolates appeared to be variants of the same virus, probably involved in a persistent infectious cycle within the T. brasiliensis colony. Using recombination analysis, we detected a statistically significant event in Spike gene, which was reinforced by phylogenetic tree incongruence analysis, involving novel Tb1 and AlphaCoVs identified in Eptesicus fuscus (family Vespertilionidae) from the U.S. The putative recombinant region is in the S1 subdomain of the Spike gene, encompassing the potential receptor-binding domain of AlphaCoVs. This study reports the first AlphaCoV genomes in molossids from the Americas and provides new insights into recombination as an important mode of evolution of coronaviruses involved in cross-species transmission. IMPORTANCE This study generated three novel complete AlphaCoV genomes (Tb1, Tb2, and Tb3 isolates) identified in individuals of Tadarida brasiliensis from Argentina, which showed two different evolutionary patterns and are the first to be reported in the family Molossidae in the Americas. The novel Tb1 isolate was found to be involved in a putative recombination event with alphacoronaviruses identified in bats of the genus Eptesicus from the U.S., whereas isolates Tb2 and Tb3 were found in different collection seasons and might be involved in persistent viral infections in the bat colony. These findings contribute to our knowledge of the global diversity of bat coronaviruses in poorly studied species and highlight the different evolutionary aspects of AlphaCoVs circulating in bat populations in Argentina.

The role of the endocannabinoid system in tooth eruption: An ex vivo study

The aim was to characterise the endocannabinoid system (ECS) in the dental pulp of teeth at different stages of eruption. Pulp of: erupted premolars (EPM), third molars in pre-eruptive (PThM), intraosseous (IThM) and eruptive stages (EThM) (n = 12 each group) were used. Messenger RNA expression of components of the ECS as cannabinoid receptors (CBr1 and CBr2), and anandamide synthetizing (NAPE-PLD) and degradation (FAAH) enzymes were measured by RT-PCR. Data were analysed using Student's t-test for comparisons between two groups and one-way analysis of variance and Tukey's post-test for multiple comparisons (statistical significance: p < 0.05). mRNA expression of CBr2, NAPE-PLD and FAAH was similar in the studied stages, was lower in IThM than in PThM and EThM, and the lowest in EThM (p < 0.01); of note, CBr2 mRNA expression was not detected in EThM. CBr1 mRNA did not differ significantly between IThM and PThM but was lower in EThM (p < 0.01). The absence of CBr2 and presence of CBr1 in EThM suggest the involvement of the ECS via CBr1 as a mediator of tooth and bone tissue homeostasis during tooth eruption.

Mechanosensitive aquaporins

Cellular systems must deal with mechanical forces to satisfy their physiological functions. In this context, proteins with mechanosensitive properties play a crucial role in sensing and responding to environmental changes. The discovery of aquaporins (AQPs) marked a significant breakthrough in the study of water transport. Their transport capacity and regulation features make them key players in cellular processes. To date, few AQPs have been reported to be mechanosensitive. Like mechanosensitive ion channels, AQPs respond to tension changes in the same range. However, unlike ion channels, the aquaporin's transport rate decreases as tension increases, and the molecular features of the mechanism are unknown. Nevertheless, some clues from mechanosensitive ion channels shed light on the AQP-membrane interaction. The GxxxG motif may play a critical role in the water permeation process associated with structural features in AQPs. Consequently, a possible gating mechanism triggered by membrane tension changes would involve a conformational change in the cytoplasmic extreme of the single file region of the water pathway, where glycine and histidine residues from loop B play a key role. In view of their transport capacity and their involvement in relevant processes related to mechanical forces, mechanosensitive AQPs are a fundamental piece of the puzzle for understanding cellular responses.

Biochemical and Structural Characterization of CRH-1, a Carbapenemase from Chromobacterium haemolyticum Related to KPC β-Lactamases

KPC-2 is one of the most relevant serine-carbapenemases among the carbapenem-resistant Enterobacterales. We previously isolated from the environmental species Chromobacterium haemolyticum a class A CRH-1 β-lactamase displaying 69% amino acid sequence identity with KPC-2. The objective of this study was to analyze the kinetic behavior and crystallographic structure of this β-lactamase. Our results showed that CRH-1 can hydrolyze penicillins, cephalosporins (except ceftazidime), and carbapenems with similar efficacy compared to KPC-2. Inhibition kinetics showed that CRH-1 is not well inhibited by clavulanic acid, in contrast to efficient inhibition by avibactam (AVI). The high-resolution crystal of the apoenzyme showed that CRH-1 has a similar folding compared to other class A β-lactamases. The CRH-1/AVI complex showed that AVI adopts a chair conformation, stabilized by hydrogen bonds to Ser70, Ser237, Asn132, and Thr235. Our findings highlight the biochemical and structural similarities of CRH-1 and KPC-2 and the potential clinical impact of this carbapenemase in the event of recruitment by pathogenic bacterial species.

The ephemeral record: The role of opportunistic animal resources in the archaeology of Pampa and Patagonia

The acquisition of opportunistic animal resources by hunter-gatherers-such as scavenged carcasses-is a well-known subsistence strategy. It is frequently mentioned in the context of the history of early human evolution, but not regularly considered among the strategies utilized by more recent foragers of the Southern Cone of South America. Historical and ethnographic information presented here suggests that the use of opportunistic animal resources was a strategy used under a number of conditions but only partially documented in the archaeological literature. We also present archaeological evidence from four sites-Guardia del Río, Paso Otero 1, Ponsonby, and Myren-in different Pampean and Patagonian settings where relevant guanaco (Lama guanicoe) bone assemblages were recovered. These sites record minimal anthropic involvement, basically cut marks on some guanaco bones accompanied by few stone tools, that we interpret as evidence for access and use of water logged immobilized or recently dead animals. Archaeological evidence for the use of these scavenging strategies is difficult to obtain at large archaeological sites that usually result from multiple occupations, since the distinction between the acquisition of actively pursued versus opportunistic animal resources is not straightforward. One conclusion from our review is that the best places to find and recognize this evidence are archaeological sites resulting from ephemeral occupations. The inclusion of these sites gives us access to crucial and rarely documented evidence for the long-term survival of hunter-gatherers.

Films of Poly(Hydroxybutyrate) (PHB) and Copper with Antibacterial Activity

Poly(3-hydroxybutyrate), PHB, is a hydrophobic biopolymer with good mechanical and barrier properties. However, neat PHB is a semicrystalline polymer with a relative high degree of crystallinity and poor film properties. In this work, this biopolymer was plasticized with glycerol tributyrate and functionalized with copper (II) sulfate, allowing us to obtain biodegradable antimicrobial flexible films. Films with the minimum inhibitory concentration (MIC) of copper (II) sulfate presented a higher roughness than neat PHB films. The presence of plasticizer significantly improved the copper sulfate diffusion process, which was evidenced by a greater inhibition halo for plasticized materials compared to unplasticized ones, at the same salt concentration. Plasticized PHB with 2.5% copper (II) sulfate inhibited both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomona aeruginosa) bacteria, as determined by the bacterial inhibition halo. In addition, neat PHB films and PHB containing copper (II) sulfate did not show in vitro cytotoxicity in the L-929 cell line. Thus, plasticized PHB functionalized with copper (II) sulfate can be used as biodegradable antimicrobial flexible films for different applications.

Dengue virus NS5 degrades ERC1 during infection to antagonize NF-kB activation

Dengue virus (DENV) is the most important human virus transmitted by mosquitos. Dengue pathogenesis is characterized by a large induction of proinflammatory cytokines. This cytokine induction varies among the four DENV serotypes (DENV1 to 4) and poses a challenge for live DENV vaccine design. Here, we identify a viral mechanism to limit NF-κB activation and cytokine secretion by the DENV protein NS5. Using proteomics, we found that NS5 binds and degrades the host protein ERC1 to antagonize NF-κB activation, limit proinflammatory cytokine secretion, and reduce cell migration. We found that ERC1 degradation involves unique properties of the methyltransferase domain of NS5 that are not conserved among the four DENV serotypes. By obtaining chimeric DENV2 and DENV4 viruses, we map the residues in NS5 for ERC1 degradation, and generate recombinant DENVs exchanging serotype properties by single amino acid substitutions. This work uncovers a function of the viral protein NS5 to limit cytokine production, critical to dengue pathogenesis. Importantly, the information provided about the serotype-specific mechanism for counteracting the antiviral response can be applied to improve live attenuated vaccines.

Influence of Experimental Warming on the Rate and Duration of Fruit Growth and Oil Accumulation in Young Olive Trees (cvs. Arbequina, Coratina)

Olive tree cultivation in new warmer areas and climate change have increased the global interest in understanding how air temperature affects both fruit growth and oil accumulation. The aims of this study were to evaluate the rate and duration of fruit growth and oil accumulation in response to experimental warming (+3) in a semiarid region of Argentina; and assess how warming affected fatty acid composition. Young, potted olive trees (cvs. Arbequina, Coratina) were warmed (T+) or maintained near ambient temperature (T0) inside open top chambers in the field during oil accumulation in 2014-2015 or 2015-2016 using different trees in each season. Warming reduced the rate of both fruit growth and oil accumulation in T+ compared to T0 in both cultivars. These rate reductions under T+ led to large decreases in final fruit dry weight and oil concentration. In contrast, the durations (i.e., days) of fruit growth and oil accumulation were most often not affected. Cultivar x temperature interactions were observed in 2014-2015 with warming decreasing oleic acid and increasing linoleic acid in cv. Arbequina, while cv. Coratina showed no response to warming. However, no interactions were found in 2015-2016. Studying how fruit growth and oil accumulation respond to adaptation strategies against increasing air temperatures should be a priority in both young and mature olive trees of numerous cultivars given crop expansion to new regions and future climate scenarios.

cis-Acting Element at the 5' Noncoding Region of Tacaribe Virus S RNA Modulates Genome Replication

Tacaribe virus (TCRV) is the prototype of New World mammarenaviruses, a group that includes several members that cause hemorrhagic fevers in humans. The TCRV genome comprises two RNA segments, named S (small) and L (large). Both genomic segments contain noncoding regions (NCRs) at their 5' and 3' ends. While the 5'- and 3'-terminal 19-nucleotide sequences are known to be essential for promoter function, the role of their neighboring internal noncoding region (iNCR) sequences remains poorly understood. To analyze the relevance of the 5' and 3' iNCRs in TCRV S RNA synthesis, mutant S-like minigenomes and miniantigenomes were generated. Using a minireplicon assay, Northern blotting, and reverse transcription-quantitative PCR, we demonstrated that the genomic 5' iNCR is specifically engaged in minigenome replication yet is not directly involved in minigenome transcription, and we showed that the S genome 3' iNCR is barely engaged in this process. Analysis of partial deletions and point mutations, as well as total or partial substitution of the 5' iNCR sequence, led us to conclude that the integrity of the whole genomic 5' iNCR is essential and that a local predicted secondary structure or RNA-RNA interactions between the 5' and 3' iNCRs are not strictly required for viral S RNA synthesis. Furthermore, we employed a TCRV reverse genetic approach to ask whether manipulation of the S genomic 5' iNCR sequence may be suitable for viral attenuation. We found that mutagenesis of the 5' promoter-proximal subregion slightly impacted recombinant TCRV virulence in vivo. IMPORTANCE The Mammarenavirus genus of the Arenaviridae family includes several members that cause severe hemorrhagic fevers associated with high morbidity and mortality rates, for which no FDA-approved vaccines and limited therapeutic resources are available. We provide evidence demonstrating the specific involvement of the TCRV S 5' noncoding sequence adjacent to the viral promoter in replication. In addition, we examined the relevance of this region in the context of an in vivo infection. Our findings provide insight into the mechanism through which this 5' viral RNA noncoding region assists the L polymerase for efficient viral S RNA synthesis. Also, these findings expand our understanding of the effect of genetic manipulation of New World mammarenavirus sequences aimed at the rational design of attenuated recombinant virus vaccine platforms.

Functional Characterization of the Co2+ Transporter AitP in Sinorhizobium meliloti: A New Player in Fe2+ Homeostasis

Co2+ induces the increase of the labile-Fe pool (LIP) by Fe-S cluster damage, heme synthesis inhibition, and "free" iron import, which affects cell viability. The N2-fixing bacteria, Sinorhizobium meliloti, is a suitable model to determine the roles of Co2+-transporting cation diffusion facilitator exporters (Co-eCDF) in Fe2+ homeostasis because it has a putative member of this subfamily, AitP, and two specific Fe2+-export systems. An insertional mutant of AitP showed Co2+ sensitivity and accumulation, Fe accumulation and hydrogen peroxide sensitivity, but not Fe2+ sensitivity, despite AitP being a bona fide low affinity Fe2+ exporter as demonstrated by the kinetic analyses of Fe2+ uptake into everted membrane vesicles. Suggesting concomitant Fe2+-dependent induced stress, Co2+ sensitivity was increased in strains carrying mutations in AitP and Fe2+ exporters which did not correlate with the Co2+ accumulation. Growth in the presence of sublethal Fe2+ and Co2+ concentrations suggested that free Fe-import might contribute to Co2+ toxicity. Supporting this, Co2+ induced transcription of Fe-import system and genes associated with Fe homeostasis. Analyses of total protoporphyrin content indicates Fe-S cluster attack as the major source for LIP. AitP-mediated Fe2+-export is likely counterbalanced via a nonfutile Fe2+-import pathway. Two lines of evidence support this: (i) an increased hemin uptake in the presence of Co2+ was observed in wild-type (WT) versus AitP mutant, and (ii) hemin reversed the Co2+ sensitivity in the AitP mutant. Thus, the simultaneous detoxification mediated by AitP aids cells to orchestrate an Fe-S cluster salvage response, avoiding the increase in the LIP caused by the disassembly of Fe-S clusters or free iron uptake. IMPORTANCE Cross-talk between iron and cobalt has been long recognized in biological systems. This is due to the capacity of cobalt to interfere with proper iron utilization. Cells can detoxify cobalt by exporting mechanisms involving membrane proteins known as exporters. Highlighting the cross-talk, the capacity of several cobalt exporters to also export iron is emerging. Although biologically less important than Fe2+, Co2+ induces toxicity by promoting intracellular Fe release, which ultimately causes additional toxic effects. In this work, we describe how the rhizobia cells solve this perturbation by clearing Fe through a Co2+ exporter, in order to reestablish intracellular Fe levels by importing nonfree Fe, heme. This piggyback-ride type of transport may aid bacterial cells to survive in free-living conditions where high anthropogenic Co2+ content may be encountered.

Outbreak of Klebsiella pneumoniae ST11 Resistant To Ceftazidime-Avibactam Producing KPC-31 and the Novel Variant KPC-115 during COVID-19 Pandemic in Argentina

We describe an outbreak of Klebsiella pneumoniae sequence type 11 (ST11) producing KPC variants resistant to ceftazidime-avibactam. Six patients hospitalized in the intensive care unit (mostly due to critical COVID pneumonia) presented infection or colonization by this bacterium. They had several comorbidities and required mechanical ventilation, central venous catheters, and urinary catheters. All 6 patients had a history of fecal colonization with KPC-producing Enterobacterales (KPC-E). Three of them had previous episodes of infection with ceftazidime-avibactam-susceptible KPC-producing K. pneumoniae, which were treated with ceftazidime-avibactam. Several phenotypic methods failed to detect carbapenemase production in these 6 ceftazidime-avibactam-resistant isolates, and they showed in vitro susceptibility to imipenem and meropenem. All of them rendered positive results for blaKPC by PCR, and amplicon sequencing identified blaKPC-31 variant in 5 isolates and a novel variant, named blaKPC-115, in the other. Moreover, matrix-assisted laser desorption ionization-time of flight mass spectrometry was able to detect KPC in all isolates. Ceftazidime-avibactam-resistant isolates, as well as those recovered from previous infection episodes (KPC-3-producing K. pneumoniae, ceftazidime-avibactam susceptible), displayed a unique pulse type and belonged to ST11. Based on whole-genome sequencing results of selected isolates, less than 7 single-nucleotide polymorphisms were identified among them, which was indicative of the presence of a unique clone. Both in vivo selection and horizontal transmission seemed to have occurred in our hospital. Detection of these strains is challenging for the laboratory. History of previous KPC-E infections or colonization and systematic testing for resistance to ceftazidime-avibactam might help raise awareness of this possibility. IMPORTANCE Klebsiella pneumoniae is one of the main bacteria that cause infections in health care settings. This pathogen has developed a high level of resistance to many antibiotics. Some K. pneumoniae isolates can produce an enzyme known as carbapenemase KPC, making carbapenems (considered the last line for therapy) not effective to treat their infections. The combination ceftazidime-avibactam, approved by FDA in 2015, is useful to treat infections caused by KPC-producing K. pneumoniae. This study describes the emergence, in one hospital in Argentina, of K. pneumoniae isolates that produce KPC variants (KPC-31 and KPC-115) resistant to ceftazidime-avibactam. The ceftazidime-avibactam-resistant bacteria were isolated in inpatients, including some that previously received this combination as treatment. Transmission of this strain to other patients also occurred in the studied period. Detection of these bacteria is challenging for the laboratory. The knowledge and awareness of the emergence of this pathogen in our region are highly valuable.

RcgA and RcgR, Two Novel Proteins Involved in the Conjugative Transfer of Rhizobial Plasmids

Rhizobia are Gram-negative bacteria that are able to establish a nitrogen-fixing symbiotic interaction with leguminous plants. Rhizobia genomes usually harbor several plasmids which can be transferred to other organisms by conjugation. Two main mechanisms of the regulation of rhizobial plasmid transfer have been described: quorum sensing (QS) and the rctA/rctB system. Nevertheless, new genes and molecules that modulate conjugative transfer have recently been described, demonstrating that new actors can tightly regulate the process. In this work, by means of bioinformatics tools and molecular biology approaches, two hypothetical genes are identified as playing key roles in conjugative transfer. These genes are located between conjugative genes of plasmid pRfaLPU83a from Rhizobium favelukesii LPU83, a plasmid that shows a conjugative transfer behavior depending on the genomic background. One of the two mentioned genes, rcgA, is essential for conjugation, while the other, rcgR, acts as an inhibitor of the process. In addition to introducing this new regulatory system, we show evidence of the functions of these genes in different genomic backgrounds and confirm that homologous proteins from non-closely related organisms have the same functions. These findings set up the basis for a new regulatory circuit of the conjugative transfer of plasmids. IMPORTANCE Extrachromosomal DNA elements, such as plasmids, allow for the adaptation of bacteria to new environments by conferring new determinants. Via conjugation, plasmids can be transferred between members of the same bacterial species, different species, or even to organisms belonging to a different kingdom. Knowledge about the regulatory systems of plasmid conjugative transfer is key in understanding the dynamics of their dissemination in the environment. As the increasing availability of genomes raises the number of predicted proteins with unknown functions, deeper experimental procedures help to elucidate the roles of these determinants. In this work, two uncharacterized proteins that constitute a new regulatory circuit with a key role in the conjugative transfer of rhizobial plasmids were discovered.

Detecting KPC-2 and NDM-1 Coexpression in Klebsiella pneumoniae Complex from Human and Animal Hosts in South America

Reports of Gram-negative bacteria harboring multiple carbapenemase genes have increased in South America, leading to an urgent need for appropriate microbiological diagnosis. We evaluated phenotypic methods for detecting Klebsiella pneumoniae carbapenemase 2 (KPC-2) and New Delhi metallo-β-lactamase-1 (NDM-1) coexpression in members of the K. pneumoniae complex (i.e., K. pneumoniae, K. quasipneumoniae, and K. variicola) isolated from human and animal hosts, based on inhibition of ceftazidime-avibactam (CZA) and aztreonam (ATM) by dipicolinic acid (DPA), EDTA, or avibactam (AVI). While the presence of blaKPC-2 and blaNDM-1 genes was confirmed by whole-genome sequencing, PCR, and/or GeneXpert, coexpression was successfully detected based on the following: (i) a ≥5-mm increase in the zone diameter of ATM (30 µg) disks plus AVI (4 or 20 µg) and ≥4-mm and ≥10-mm increases in the zone diameters for "CZA 50" (30 µg ceftazidime [CAZ] and 20 µg AVI) and "CZA 14" (10 µg CAZ and 4 µg AVI) disks, respectively, when we added DPA (1 mg/disk) or EDTA (5 mM) in a combined disk test (CDT); (ii) a positive ghost zone (synergism) between ATM (30 µg) and CZA 50 disks and between CZA 50 and DPA (1 mg) disks, using the double-disk synergy test (DDST) at a disk-disk distance of 2.5 cm; (iii) ≥3-fold MIC reductions of ATM and CZA in the presence of AVI (4 µg/mL), DPA (500 µg/mL), or EDTA (320 µg/mL); and (iv) immunochromatography. Although our results demonstrated that inhibition by AVI, DPA, and EDTA may provide simple and inexpensive methods for the presumptive detection of coexpression of KPC-2 and NDM-1 in members of the K. pneumoniae complex, additional studies are necessary to confirm the accuracy of these methodologies by testing other Gram-negative bacterial species and other KPC and NDM variants coexpressed by WHO critical priority pathogens detected worldwide. IMPORTANCE Alerts regarding the emergence and increase of combinations of carbapenemases in Enterobacterales in Latin America and the Caribbean have recently been issued by PAHO and WHO, emphasizing the importance of appropriate microbiological diagnosis and the effective and articulated implementation of infection prevention and control programs. In this study, we evaluated methods based on inhibition of ceftazidime (CAZ), ceftazidime-avibactam (CZA), and aztreonam (ATM) by dipicolinic acid (DPA), EDTA, and avibactam (AVI) inhibitors for the identification of KPC-2- and NDM-1-coexpression in members of the K. pneumoniae complex recovered from human and animal hosts. Our results demonstrate that inhibition by AVI, DPA, and EDTA may provide simple and inexpensive methods for the presumptive detection of coexpression of KPC-2 and NDM-1 in members of the K. pneumoniae complex.

Dopamine Modulates Adaptive Forgetting in Medial Prefrontal Cortex

Active forgetting occurs in many species, but how behavioral control mechanisms influence which memories are forgotten remains unknown. We previously found that when rats need to retrieve a memory to guide exploration, it reduces later retention of other competing memories encoded in that environment. As with humans, this retrieval-induced forgetting relies on prefrontal control processes. Dopaminergic input to the prefrontal cortex is important for executive functions and cognitive flexibility. We found that, in a similar way, retrieval-induced forgetting of competing memories in male rats requires prefrontal dopamine signaling through D1 receptors. Blockade of medial prefrontal cortex D1 receptors as animals encountered a familiar object impaired active forgetting of competing object memories as measured on a later long-term memory test. Inactivation of the ventral tegmental area produced the same pattern of behavior, a pattern that could be reversed by concomitant activation of prefrontal D1 receptors. We observed a bidirectional modulation of retrieval-induced forgetting by agonists and antagonists of D1 receptors in the medial prefrontal cortex. These findings establish the essential role of prefrontal dopamine in the active forgetting of competing memories, contributing to the shaping of retention in response to the behavioral goals of an organism.SIGNIFICANCE STATEMENT Forgetting is a ubiquitous phenomenon that is actively promoted in many species. The very act of remembering some experiences can cause forgetting of others, in both humans and rats. This retrieval-induced forgetting process is thought to be driven by inhibitory control signals from the prefrontal cortex that target areas where the memories are stored. Here we started disentangling the neurochemical signals in the prefrontal cortex that are essential to retrieval-induced forgetting. We found that, in rats, the release of dopamine in this area, acting through D1 receptors, was essential to causing active forgetting of competing memories. Inhibition of D1 receptors impaired forgetting, while activation increased forgetting. These findings are important, because the mechanisms of active forgetting and their linkage to goal-directed behavior are only beginning to be understood.

Sex-specific spatial use of the winter foraging areas by Magellanic penguins and assessment of potential conflicts with fisheries during winter dispersal

Magellanic penguins (Spheniscus magellanicus) disperse widely during winter and are a major consumer of marine resources over the Patagonian Shelf. Magellanic penguins were equipped with geolocators at Martillo Island in late February- early March 2017 and recaptured at the beginning of the next breeding season to recover the devices and to collect blood samples for stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis. We evaluated their whole winter dispersal and their trophic niche by sex during the last month of the winter dispersal. Also, we evaluated their spatial overlap with bottom trawl and shrimp fisheries using data from satellite fisheries monitoring. Penguins dispersed northwards up to 42°S and showed latitudinal spatial segregation between sexes during May to August (females were located further north than males). In contrast, during the last month of the winter dispersal females were located more southerly and showed lower trophic position than males. Also, females did not dive as deep as males during winter. We found high overlap between both fisheries and penguin’s spatial use in regions with documented interaction. However, no sex-specific statistical differences with fisheries overlap were found. Our results highlight the importance of understanding the spatial domains of each sex and assessment of their potential conflicts with bottom trawl fishery and shrimp fishery during the winter period.

Preservation of the Antioxidant Capacity of Resveratrol via Encapsulation in Niosomes

Resveratrol (RSV) is a natural polyphenol which produces several benefits to human health, being the trans-isomer the most bioactive. However, its systemic absorption is limited due to its low water solubility, that reduces the oral bioavailability, and its chemical instability (owing to the trans-cis RSV isomer conversion upon light irradiation). Thus, encapsulation of this bioactive compound is required to protect it from destructive environmental conditions. Here, trans-RSV was encapsulated in food grade nanovesicles formed by Tween 80 and Span 80, with or without the addition of dodecanol (Dod) as membrane stabilizer. The size and shape of niosomes were evaluated by microscopy (TEM) and light scattering. RSV was successfully encapsulated in the vesicular systems (49-57%). The effect of Dod in the membrane bilayer was evaluated on the RSV in vitro release experiments under simulated gastrointestinal conditions. The total antioxidant capacity of the encapsulated polyphenol was measured using radicals' assays (DPPH and ABTS). The niosomes were able to maintain almost the total antioxidant capacity of encapsulated RSV, also preserved the ~85% of trans-RSV, thus offering considerable protection against high energy irradiation. These results make these systems suitable for different applications, particularly for photosensitive compounds.

A Stringent-Response-Defective Bradyrhizobium diazoefficiens Strain Does Not Activate the Type 3 Secretion System, Elicits an Early Plant Defense Response, and Circumvents NH4NO3-Induced Inhibition of Nodulation

When subjected to nutritional stress, bacteria modify their amino acid metabolism and cell division activities by means of the stringent response, which is controlled by the Rsh protein in alphaproteobacteria. An important group of alphaproteobacteria are the rhizobia, which fix atmospheric N2 in symbiosis with legume plants. Although nutritional stress is common for rhizobia while infecting legume roots, the stringent response has scarcely been studied in this group of soil bacteria. In this report, we obtained a mutant with a kanamycin resistance insertion in the rsh gene of Bradyrhizobium diazoefficiens, the N2-fixing symbiont of soybean. This mutant was defective for type 3 secretion system induction, plant defense suppression at early root infection, and nodulation competition. Furthermore, the mutant produced smaller nodules, although with normal morphology, which led to lower plant biomass production. Soybean (Glycine max) genes GmRIC1 and GmRIC2, involved in autoregulation of nodulation, were upregulated in plants inoculated with the mutant under the N-free condition. In addition, when plants were inoculated in the presence of 10 mM NH4NO3, the mutant produced nodules containing bacteroids, and GmRIC1 and GmRIC2 were downregulated. The rsh mutant released more auxin to the culture supernatant than the wild type, which might in part explain its symbiotic behavior in the presence of combined N. These results indicate that the B. diazoefficiens stringent response integrates into the plant defense suppression and regulation of nodulation circuits in soybean, perhaps mediated by the type 3 secretion system.IMPORTANCE The symbiotic N2 fixation carried out between prokaryotic rhizobia and legume plants performs a substantial contribution to the N cycle in the biosphere. This symbiotic association is initiated when rhizobia infect and penetrate the root hairs, which is followed by the growth and development of root nodules, within which the infective rhizobia are established and protected. Thus, the nodule environment allows the expression and function of the enzyme complex that catalyzes N2 fixation. However, during early infection, the rhizobia find a harsh environment while penetrating the root hairs. To cope with this nuisance, the rhizobia mount a stress response known as the stringent response. In turn, the plant regulates nodulation in response to the presence of alternative sources of combined N in the surrounding medium. Control of these processes is crucial for a successful symbiosis, and here we show how the rhizobial stringent response may modulate plant defense suppression and the networks of regulation of nodulation.

Probiotic lactobacilli as a promising strategy to ameliorate disorders associated with intestinal inflammation induced by a non-steroidal anti-inflammatory drug

Damage to the small intestine caused by non-steroidal anti-inflammatory drugs (NSAIDs) occurs more frequently than in the upper gastrointestinal tract, is more difficult to diagnose and no effective treatments exist. Hence, we investigated whether probiotics can control the onset of this severe condition in a murine model of intestinal inflammation induced by the NSAID, indomethacin. Probiotic supplementation to mice reduce the body weight loss, anemia, shortening of the small intestine, cell infiltration into the intestinal tissue and the loss of Paneth and Goblet cells associated with intestinal inflammation. Furthermore, a high antimicrobial activity in the intestinal fluids of mice fed with probiotics compared to animals on a conventional diet was elicited against several pathogens. Interestingly, probiotics dampened the oxidative stress and several local and systemic markers of an inflammatory process, as well as increased the secretion of IL-10 by regulatory T cells. Even more importantly, probiotics induced important changes in the large intestine microbiota characterized by an increase in anaerobes and lactobacilli, and a significant decrease in total enterobacteria. We conclude that oral probiotic supplementation in NSAID-induced inflammation increases intestinal antimicrobial activity and reinforces the intestinal epithelial barrier in order to avoid pathogens and commensal invasion and maintain intestinal homeostasis.

GAS6 signaling tempers Th17 development in patients with multiple sclerosis and helminth infection

Multiple sclerosis (MS) is a highly disabling neurodegenerative autoimmune condition in which an unbalanced immune response plays a critical role. Although the mechanisms remain poorly defined, helminth infections are known to modulate the severity and progression of chronic inflammatory diseases. The tyrosine kinase receptors TYRO3, AXL, and MERTK (TAM) have been described as inhibitors of the immune response in various inflammatory settings. We show here that patients with concurrent natural helminth infections and MS condition (HIMS) had an increased expression of the negative regulatory TAM receptors in antigen-presenting cells and their agonist GAS6 in circulating CD11b^high and CD4⁺ T cells compared to patients with only MS. The Th17 subset was reduced in patients with HIMS with a subsequent downregulation of its pathogenic genetic program. Moreover, these CD4⁺ T cells promoted lower levels of the co-stimulatory molecules CD80, CD86, and CD40 on dendritic cells compared with CD4⁺ T cells from patients with MS, an effect that was GAS6-dependent. IL-10⁺ cells from patients with HIMS showed higher GAS6 expression levels than Th17 cells, and inhibition of phosphatidylserine/GAS6 binding led to an expansion of Th17 effector genes. The addition of GAS6 on activated CD4⁺ T cells from patients with MS restrains the Th17 gene expression signature. This cohort of patients with HIMS unravels a promising regulatory mechanism to dampen the Th17 inflammatory response in autoimmunity.

Helminths have co-evolved with human civilization, and the rapid exclusion from their environment, in the last few decades, has tremendously affected the immune development and regulation. Moreover, several epidemiological studies have shown an inverse correlation between the exposure of these organisms and the development of autoimmunity in industrialized countries. In this sense, helminth therapy appears to be a promising concept to oppose chronic inflammatory and autoimmune diseases because they are master manipulators of host immunity, albeit the mechanisms remain poorly defined. For this reason, it is essential to decipher the main regulatory pathways to hijack the immune response in the absence of parasite infection. Our research described how helminth infection promotes regulatory mechanisms based on the tyrosine kinase TYRO3, AXL, MERTK (TAM) receptors, and their ligand GAS6 to dampen Th17 development and the inflammatory response in patients with multiple sclerosis (MS), a neurodegenerative autoimmune disorder. We show here that GAS6 plays a critical role in the regulation of pro-inflammatory cytokines, transcriptional programs, and plasticity of IL-17 subset. Our work substantiates the hypothesis that enhancing the TAM axis in a manner similar to helminth infection could be a promising alternative for autoimmune diseases.

Baculovirus Transduction in Mammalian Cells Is Affected by the Production of Type I and III Interferons, Which Is Mediated Mainly by the cGAS-STING Pathway

The baculovirus Autographa californica multiple nucleopolyhedrovirus is an insect virus with a circular double-stranded DNA genome, which, among other multiple biotechnological applications, is used as an expression vector for gene delivery in mammalian cells. Nevertheless, the nonspecific immune response triggered by viral vectors often suppresses transgene expression. To understand the mechanisms involved in that response, in the present study, we studied the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway by using two approaches: the genetic edition through CRISPR/Cas9 technology of genes encoding STING or cGAS in NIH/3T3 murine fibroblasts and the infection of HEK293 and HEK293 T human epithelial cells, deficient in cGAS and in cGAS and STING expression, respectively. Overall, our results suggest the existence of two different pathways involved in the establishment of the antiviral response, both dependent on STING expression. Particularly, the cGAS-STING pathway resulted in the more relevant production of beta interferon (IFN-β) and IFN-λ1 in response to baculovirus infection. In human epithelial cells, IFN-λ1 production was also induced in a cGAS-independent and DNA-protein kinase (DNA-PK)-dependent manner. Finally, we demonstrated that these cellular responses toward baculovirus infection affect the efficiency of transduction of baculovirus vectors.IMPORTANCE Baculoviruses are nonpathogenic viruses that infect mammals, which, among other applications, are used as vehicles for gene delivery. Here, we demonstrated that the cytosolic DNA sensor cGAS recognizes baculoviral DNA and that the cGAS-STING axis is primarily responsible for the attenuation of transduction in human and mouse cell lines through type I and type III IFNs. Furthermore, we identified DNA-dependent protein kinase (DNA-PK) as a cGAS-independent and alternative DNA cytosolic sensor that contributes less to the antiviral state in baculovirus infection in human epithelial cells than cGAS. Knowledge of the pathways involved in the response of mammalian cells to baculovirus infection will improve the use of this vector as a tool for gene therapy.

Structure of the unusual Sinorhizobium fredii HH103 lipopolysaccharide and its role in symbiosis

Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of Sinorhizobium fredii HH103, rkpA, that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 rkpLMNOPQ operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-l-glycero-l-manno-nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 rkpM mutant cannot produce KPS and displays an altered LPS structure. Here, we analyzed the LPS structure of HH103 rkpA, focusing on the carbohydrate portion, and found that it contains a highly heterogeneous lipid A and a peculiar core oligosaccharide composed of an unusually high number of hexuronic acids containing β-configured Pse5NAc7(3OHBu). This pseudaminic acid derivative, in its α-configuration, was the only structural component of the S. fredii HH103 KPS and, to the best of our knowledge, has never been reported from any other rhizobial LPS. We also show that Pse5NAc7(3OHBu) is the complete or partial epitope for a mAb, NB6-228.22, that can recognize the HH103 LPS, but not those of most of the S. fredii strains tested here. We also show that the LPS from HH103 rkpM is identical to that of HH103 rkpA but devoid of any Pse5NAc7(3OHBu) residues. Notably, this rkpM mutant was severely impaired in symbiosis with its host, Macroptilium atropurpureum.

Citrus Psorosis Virus Movement Protein Contains an Aspartic Protease Required for Autocleavage and the Formation of Tubule-Like Structures at Plasmodesmata

Plant virus cell-to-cell movement is an essential step in viral infections. This process is facilitated by specific virus-encoded movement proteins (MPs), which manipulate the cell wall channels between neighboring cells known as plasmodesmata (PD). Citrus psorosis virus (CPsV) infection in sweet orange involves the formation of tubule-like structures within PD, suggesting that CPsV belongs to "tubule-forming" viruses that encode MPs able to assemble a hollow tubule extending between cells to allow virus movement. Consistent with this hypothesis, we show that the MP of CPsV (MPCPsV) indeed forms tubule-like structures at PD upon transient expression in Nicotiana benthamiana leaves. Tubule formation by MPCPsV depends on its cleavage capacity, mediated by a specific aspartic protease motif present in its primary sequence. A single amino acid mutation in this motif abolishes MPCPsV cleavage, alters the subcellular localization of the protein, and negatively affects its activity in facilitating virus movement. The amino-terminal 34-kDa cleavage product (34KCPsV), but not the 20-kDa fragment (20KCPsV), supports virus movement. Moreover, similar to tubule-forming MPs of other viruses, MPCPsV (and also the 34KCPsV cleavage product) can homooligomerize, interact with PD-located protein 1 (PDLP1), and assemble tubule-like structures at PD by a mechanism dependent on the secretory pathway. 20KCPsV retains the protease activity and is able to cleave a cleavage-deficient MPCPsV in trans Altogether, these results demonstrate that CPsV movement depends on the autolytic cleavage of MPCPsV by an aspartic protease activity, which removes the 20KCPsV protease and thereby releases the 34KCPsV protein for PDLP1-dependent tubule formation at PD.IMPORTANCE Infection by citrus psorosis virus (CPsV) involves a self-cleaving aspartic protease activity within the viral movement protein (MP), which results in the production of two peptides, termed 34KCPsV and 20KCPsV, that carry the MP and viral protease activities, respectively. The underlying protease motif within the MP is also found in the MPs of other members of the Aspiviridae family, suggesting that protease-mediated protein processing represents a conserved mechanism of protein expression in this virus family. The results also demonstrate that CPsV and potentially other ophioviruses move by a tubule-guided mechanism. Although several viruses from different genera were shown to use this mechanism for cell-to-cell movement, our results also demonstrate that this mechanism is controlled by posttranslational protein cleavage. Moreover, given that tubule formation and virus movement could be inhibited by a mutation in the protease motif, targeting the protease activity for inactivation could represent an important approach for ophiovirus control.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.