Mechanism for Cas4-assisted directional spacer acquisition in CRISPR-Cas.

Prokaryotes adapt to challenges from mobile genetic elements by integrating spacers derived from foreign DNA in the CRISPR array1. Spacer insertion is carried out by the Cas1-Cas2 integrase complex2-4. A substantial fraction of CRISPR-Cas systems use a Fe-S cluster containing Cas4 nuclease to ensure that spacers are acquired from DNA flanked by a protospacer adjacent motif (PAM)5,6 and inserted into the CRISPR array unidirectionally, so that the transcribed CRISPR RNA can guide target searching in a PAM-dependent manner. Here we provide a high-resolution mechanistic explanation for the Cas4-assisted PAM selection, spacer biogenesis and directional integration by type I-G CRISPR in Geobacter sulfurreducens, in which Cas4 is naturally fused with Cas1, forming Cas4/Cas1. During biogenesis, only DNA duplexes possessing a PAM-embedded 3'-overhang trigger Cas4/Cas1-Cas2 assembly. During this process, the PAM overhang is specifically recognized and sequestered, but is not cleaved by Cas4. This 'molecular constipation' prevents the PAM-side prespacer from participating in integration. Lacking such sequestration, the non-PAM overhang is trimmed by host nucleases and integrated to the leader-side CRISPR repeat. Half-integration subsequently triggers PAM cleavage and Cas4 dissociation, allowing spacer-side integration. Overall, the intricate molecular interaction between Cas4 and Cas1-Cas2 selects PAM-containing prespacers for integration and couples the timing of PAM processing with the stepwise integration to establish directionality.

Toxicity of the 3,4-Methylenedioxymethamphetamine and Its Enantiomers to Daphnia magna after Isolation by Semipreparative Chromatography.

MDMA (3,4-methylenedioxymethamphetamine) is a chiral psychoactive recreational drug sold in illicit markets as racemate. Studies on the impact of MDMA on aquatic organisms are scarce. While enantioselectivity in toxicity in animals and humans has been reported, none is reported on aquatic organisms. This study aimed to investigate the ecotoxicological effects of MDMA and its enantiomers in Daphnia magna. For that, enantiomers (enantiomeric purity > 97%) were separated by liquid chromatography using a homemade semipreparative chiral column. Daphnids were exposed to three concentrations of (R,S)-MDMA (0.1, 1.0 and 10.0 µg L-1) and two concentrations of (R)- and (S)-enantiomers (0.1 and 1.0 µg L-1) over the course of 8 days. Morphophysiological responses were dependent on the substance form and daphnia development stage, and they were overall not affected by the (R)-enantiomer. Changes in swimming behaviour were observed for both the racemate and its enantiomers, but enantioselective effects were not observed. Reproductive or biochemical changes were not observed for enantiomers whereas a significant decrease in acetylcholinesterase and catalase activity was noted at the highest concentration of (R,S)-MDMA (10 µg L-1). Overall, this study showed that sub-chronic exposure to MDMA racemate and its enantiomers can interfere with morphophysiological and swimming behaviour of D. magna. In general, the (R)-enantiomer demonstrated less toxicity than the (S)-enantiomer.

Variants in ADD1 cause intellectual disability, corpus callosum dysgenesis, and ventriculomegaly in humans.

PURPOSE: Adducins interconnect spectrin and actin filaments to form polygonal scaffolds beneath the cell membranes and form ring-like structures in neuronal axons. Adducins regulate mouse neural development, but their function in the human brain is unknown. METHODS: We used exome sequencing to uncover ADD1 variants associated with intellectual disability (ID) and brain malformations. We studied ADD1 splice isoforms in mouse and human neocortex development with RNA sequencing, super resolution imaging, and immunoblotting. We investigated 4 variant ADD1 proteins and heterozygous ADD1 cells for protein expression and ADD1-ADD2 dimerization. We studied Add1 functions in vivo using Add1 knockout mice. RESULTS: We uncovered loss-of-function ADD1 variants in 4 unrelated individuals affected by ID and/or structural brain defects. Three additional de novo copy number variations covering the ADD1 locus were associated with ID and brain malformations. ADD1 is highly expressed in the neocortex and the corpus callosum, whereas ADD1 splice isoforms are dynamically expressed between cortical progenitors and postmitotic neurons. Human variants impair ADD1 protein expression and/or dimerization with ADD2. Add1 knockout mice recapitulate corpus callosum dysgenesis and ventriculomegaly phenotypes. CONCLUSION: Our human and mouse genetics results indicate that pathogenic ADD1 variants cause corpus callosum dysgenesis, ventriculomegaly, and/or ID.

The role of the membrane-associated periodic skeleton in axons.

The identification of the membrane periodic skeleton (MPS), composed of a periodic lattice of actin rings interconnected by spectrin tetramers, was enabled by the development of super-resolution microscopy, and brought a new exciting perspective to our view of neuronal biology. This exquisite cytoskeleton arrangement plays an important role on mechanisms regulating neuronal (dys)function. The MPS was initially thought to provide mainly for axonal mechanical stability. Since its discovery, the importance of the MPS in multiple aspects of neuronal biology has, however, emerged. These comprise its capacity to act as a signaling platform, regulate axon diameter-with important consequences on the efficiency of axonal transport and electrophysiological properties- participate in the assembly and function of the axon initial segment, and control axon microtubule stability. Recently, MPS disassembly has also surfaced as an early player in the course of axon degeneration. Here, we will discuss the current knowledge on the role of the MPS in axonal physiology and disease.

Development of Styrene Maleic Acid Lipid Particles as a Tool for Studies of Phage-Host Interactions.

The infection of a bacterium by a phage starts with attachment to a receptor molecule on the host cell surface by the phage. Since receptor-phage interactions are crucial to successful infections, they are major determinants of phage host range and, by extension, of the broader effects that phages have on bacterial communities. Many receptor molecules, particularly membrane proteins, are difficult to isolate because their stability is supported by their native membrane environments. Styrene maleic acid lipid particles (SMALPs), a recent advance in membrane protein studies, are the result of membrane solubilizations by styrene maleic acid (SMA) copolymer chains. SMALPs thereby allow for isolation of membrane proteins while maintaining their native environment. Here, we explore SMALPs as a tool to isolate and study phage-receptor interactions. We show that SMALPs produced from taxonomically distant bacterial membranes allow for receptor-specific decrease of viable phage counts of several model phages that span the three largest phage families. After characterizing the effects of incubation time and SMALP concentration on the activity of three distinct phages, we present evidence that the interaction between two model phages and SMALPs is specific to bacterial species and the phage receptor molecule. These interactions additionally lead to DNA ejection by nearly all particles at high phage titers. We conclude that SMALPs are a potentially highly useful tool for phage-host interaction studies.IMPORTANCE Bacteriophages (viruses that infect bacteria or phages) impact every microbial community. All phage infections start with the binding of the viral particle to a specific receptor molecule on the host cell surface. Due to its importance in phage infections, this first step is of interest to many phage-related research and applications. However, many phage receptors are difficult to isolate. Styrene maleic acid lipid particles (SMALPs) are a recently developed approach to isolate membrane proteins in their native environment. In this study, we explore SMALPs as a tool to study phage-receptor interactions. We find that different phage species bind to SMALPs, while maintaining specificity to their receptor. We then characterize the time and concentration dependence of phage-SMALP interactions and furthermore show that they lead to genome ejection by the phage. The results presented here show that SMALPs are a useful tool for future studies of phage-receptor interactions.

An educational guide for nanopore sequencing in the classroom.

The last decade has witnessed a remarkable increase in our ability to measure genetic information. Advancements of sequencing technologies are challenging the existing methods of data storage and analysis. While methods to cope with the data deluge are progressing, many biologists have lagged behind due to the fast pace of computational advancements and tools available to address their scientific questions. Future generations of biologists must be more computationally aware and capable. This means they should be trained to give them the computational skills to keep pace with technological developments. Here, we propose a model that bridges experimental and bioinformatics concepts using the Oxford Nanopore Technologies (ONT) sequencing platform. We provide both a guide to begin to empower the new generation of educators, scientists, and students in performing long-read assembly of bacterial and bacteriophage genomes and a standalone virtual machine containing all the required software and learning materials for the course.

Functional Analysis and Antivirulence Properties of a New Depolymerase from a Myovirus That Infects Acinetobacter baumannii Capsule K45.

Acinetobacter baumannii is an important pathogen causative of health care-associated infections and is able to rapidly develop resistance to all known antibiotics, including colistin. As an alternative therapeutic agent, we have isolated a novel myovirus (vB_AbaM_B9) which specifically infects and makes lysis from without in strains of the K45 and K30 capsule types, respectively. Phage B9 has a genome of 93,641 bp and encodes 167 predicted proteins, of which 29 were identified by mass spectrometry. This phage holds a capsule depolymerase (B9gp69) able to digest extracted exopolysaccharides of both K30 and K45 strains and remains active in a wide range of pH values (5 to 9), ionic strengths (0 to 500 mM), and temperatures (20 to 80°C). B9gp69 was demonstrated to be nontoxic in a cell line model of the human lung and to make the K45 strain fully susceptible to serum killing in vitro Contrary to the case with phage, no resistance development was observed by bacteria targeted with the B9gp69. Therefore, capsular depolymerases may represent attractive antimicrobial agents against A. baumannii infections.IMPORTANCE Currently, phage therapy has revived interest for controlling hard-to-treat bacterial infections. Acinetobacter baumannii is an emerging Gram-negative pathogen able to cause a variety of nosocomial infections. Additionally, this species is becoming more resistant to several classes of antibiotics. Here we describe the isolation of a novel lytic myophage B9 and its recombinant depolymerase. While the phage can be a promising alternative antibacterial agent, its success in the market will ultimately depend on new regulatory frameworks and general public acceptance. We therefore characterized the phage-encoded depolymerase, which is a natural enzyme that can be more easily managed and used. To our knowledge, the therapeutic potential of phage depolymerase against A. baumannii is still unknown. We show for the first time that the K45 capsule type is an important virulence factor of A. baumannii and that capsule removal via the recombinant depolymerase activity helps the host immune system to combat the bacterial infection.

Shift of µ-opioid Receptor Signaling in the Dorsal Reticular Nucleus Is Implicated in Morphine-induced Hyperalgesia in Male Rats.

BACKGROUND: Increased descending pain facilitation accounts for opioid-induced hyperalgesia, but the underlying mechanisms remain elusive. Given the role of µ-opioid receptors in opioid-induced hyperalgesia in animals, the authors hypothesized that the dorsal reticular nucleus, a medullary pain facilitatory area, is involved in opioid-induced hyperalgesia through altered µ-opioid receptor signaling. METHODS: The authors used male Wistar rats (n = 5 to 8 per group), chronically infused with morphine, to evaluate in the dorsal reticular nucleus the expressions of the µ-opioid receptor and phosphorylated cAMP response element-binding, a downstream marker of excitatory µ-opioid receptor signaling. The authors used pharmacologic and gene-mediated approaches. Nociceptive behaviors were evaluated by the von Frey and hot-plates tests. RESULTS: Lidocaine fully reversed mechanical and thermal hypersensitivity induced by chronic morphine. Morphine-infusion increased µ-opioid receptor, without concomitant messenger RNA changes, and phosphorylated cAMP response element-binding levels at the dorsal reticular nucleus. µ-opioid receptor knockdown in morphine-infused animals attenuated the decrease of mechanical thresholds and heat-evoked withdrawal latencies compared with the control vector (von Frey [mean ± SD]: -17 ± 8% vs. -40 ± 9.0%; P < 0.001; hot-plate: -10 ± 5% vs. -32 ± 10%; P = 0.001). µ-opioid receptor knockdown in control animals induced the opposite (von Frey: -31 ± 8% vs. -17 ± 8%; P = 0.053; hotplate: -24 ± 6% vs. -3 ± 10%; P = 0.001). The µ-opioid receptor agonist (D-ALA2,N-ME-PHE4,GLY5-OL)-enkephalin acetate (DAMGO) decreased mechanical thresholds and did not affect heat-evoked withdrawal latencies in morphine-infused animals. In control animals, DAMGO increased both mechanical thresholds and heat-evoked withdrawal latencies. Ultra-low-dose naloxone, which prevents the excitatory signaling of the µ-opioid receptor, administered alone, attenuated mechanical and thermal hypersensitivities, and coadministered with DAMGO, restored DAMGO analgesic effects and decreased phosphorylated cAMP response element-binding levels. CONCLUSIONS: Chronic morphine shifted µ-opioid receptor signaling from inhibitory to excitatory at the dorsal reticular nucleus, likely enhancing descending facilitation during opioid-induced hyperalgesia in the rat.

Chest Wall Trauma Surgery Review.

Rib fractures are frequent in trauma patients, being most of them managed on a non-surgical way. However, in selected cases, it is advocated. Chest wall stabilization (CWS) only recently has been best characterized. Available data shows plenty of benefits related to CWS versus non-surgical treatment in selected cases. Even though, it is only performed in a small number of patients according to some national databases. There are lots of topics to define concerning CWS such as the subgroups that benefit most, the time of surgery, which ribs should be stabilized and which incision should be performed. Most of these subjects need to be tailored for each patient. So far, no guidelines for CWS are available, although some algorithms have been proposed based on a combination of clinical experience and risk factors. In high-volume trauma centers it has become a common procedure. The complexity of some cases demands a careful evaluation, especially in the context of multiple injuries, and it should be taken into account in the decision.

Lung Necrosis After Paraffin Aspiration.

BACKGROUND: Fire breather´s lung is a rare condition that occurs after hydrocarbon aspiration. Case reports published experienced a good clinical outcome with conservative treatment. To our knowledge, there are no reported cases treated with pulmonary resection. CASE PRESENTATION: We report the case of a 35-year-old female trapeze artist, who suffered an accidental ingestion/ aspiration of liquid paraffin. Persistent fever and elevated inflammatory markers without clinical improvement with antibiotics and bronchoscopy was seen. Computed tomography scan showing middle lobe necrosis and abscess motivated a middle lobectomy for infection control. Postoperative recovery was uneventful. CONCLUSION: There are some cases described in the literature, normally with a favourable evolution with conservative treatment. Therefore, it is important to acknowledge that, in patients where serious complications have arisen, despite medical therapy, surgery may have an important role, and resection of the necrotic lung may prevent its potential life-threatening consequences.

Coherent-hybrid STED: high contrast sub-diffraction imaging using a bi-vortex depletion beam.

Stimulated emission depletion (STED) fluorescence microscopy squeezes an excited spot well below the wavelength scale using a doughnut-shaped depletion beam. To generate a doughnut, a scale-free vortex phase modulation (2D-STED) is often used because it provides maximal transverse confinement and radial-aberration immunity (RAI) to the central dip. However, RAI also means blindness to a defocus term, making the axial origin of fluorescence photons uncertain within the wavelength scale provided by the confocal detection pinhole. Here, to reduce the uncertainty, we perturb the 2D-STED phase mask so as to change the sign of the axial concavity near focus, creating a dilated dip. By providing laser depletion power, the dip can be compressed back in three dimensions to retrieve lateral resolution, now at a significantly higher contrast. We test this coherent-hybrid STED (CH-STED) mode in x-y imaging of complex biological structures, such as the dividing cell. The proposed strategy creates an orthogonal direction in the STED parametric space that uniquely allows independent tuning of resolution and contrast using a single depletion beam in a conventional (circular polarization-based) STED setup.

Bacteriophages and their derivatives for the treatment and control of food-producing animal infections.

Nowadays, the world is facing an increasing emergence of antibiotic resistant bacteria. Simultaneously, the banning of some existing antibiotics and the lack of development of new antimicrobials have created an urgent need to find new alternatives against animal infections. Bacteriophages (phages) are naturally occurring predators of bacteria, ubiquitous in the environment, with high host specificity and harmless to animals. For these reasons, phages and their derivatives are being considered valuable antimicrobial alternatives and an opportunity to reduce the current use of antibiotics in agri-food production, increasing animal productivity and providing environmental protection. Furthermore, the possibility of combining phage genetic material with foreign genes encoding peptides of interest has enabled their use as vaccine delivery tools. In this case, besides bacterial infections, they might be used to prevent viral infections. This review explores current data regarding advances on the use of phages and phage-encoded proteins, such as endolysins, exolysins and depolymerases, either for therapeutic or prophylactic applications, in animal husbandry. The use of recombinant phage-derived particles or genetically modified phages, including phage vaccines, will also be reviewed.

Critical review on biofilm methods.

Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms.

The First 24 Robotic Surgeries of Hospital da Luz.

INTRODUCTION: Robotic assisted thoracic surgery (RATS) has been growing all over the world, presenting itself as an improvement over video-assisted thoracic surgery (VATS). The main advantages are the precision of the movements, as well as the three-dimensional vision with the consequent perception of the depth of the surgical field. Thus, technically more difficult procedures, such as anatomic segmentectomies and bronchoplastic resections, are facilitated. This surgical approach also improves the quality of mediastinal lymph node dissection, extremely important in lung cancer patients. OBJECTIVE: Analysis of the first 24 robotic thoracic surgeries performed at Hospital da Luz. METHODS: All robotic thoracic surgeries performed at Hospital da Luz from 2/6/2016 to this date were evaluated, concerning diagnosis, type of surgery, chest drainage time, hospitalization time, morbidity and mortality. RESULTS: Twenty-four RATS were performed, with patients having a mean age of 60.5 (39-76) years, eleven of them being male. All surgeries were performed with 3 ports of 8mm and a 12mm port for the assistant. Eighteen surgeries of pulmonary resection (75%), five surgeries for mediastinal lesions (20.8%), and one for intercostal nerve harvest for reinnervation of the brachial plexus, were performed. In the pulmonary surgeries, eleven were lobectomies (61.1%), five were anatomic segmentectomies (27.8%) and two wedge resections (11.1%). Neoplastic disease was the reason for the sixteen lung anatomic resections, two for metastatic disease and fourteen for primary lung cancer. In each case, a systemic lymph node dissection was performed. All procedures were performed without intra- or postoperative complications. Mean drainage time was 3.4 days [2-6], and mean hospitalization time was 4.8 days [3-8]. There were no mortality or major morbidity. There were two patients with prolonged air-leak up to 6 days. The morbidity after discharge was 12.5%, consisting of an apical pneumothorax that resolved spontaneously, a basal pleural effusion that resolved with outpatient thoracentesis, and a respiratory infection treated with antibiotic. CONCLUSION: The overall evaluation of this technique is still precocious, but allows to affirm that an experienced surgeon in vats surgery has a faster learning curve with this new approach. The innovation and development of new techniques in thoracic surgery are fundamental in order to allow more effective treatments, with less pain and, when possible, lung parenchyma sparing surgeries in patients with early neoplastic lung disease.

Major Complications of Videomediastinoscopy and their Resolution - a 5 year experience.

INTRODUCTION: Videomediastinoscopy is an invasive procedure for mediastinal assessment, with low rates of morbidity and mortality. Despite the low risk of complications, they can be potentially lethal if not immediately controlled. OBJECTIVE: The goal of this study is to analyse the overall incidence of complications of videomediastinoscopies, performed in the last 5 years at our department, as well as their resolution and outcomes. METHODS: A retrospective review of all videomediastinoscopies performed at a single institution during a 5-year period was performed. Major complications were defined as life-threatening events. RESULTS: During the study period, from July 2012 to July 2017, were performed 160 mediastinoscopies, 67 were diagnostic and 93 for staging. There were 3 major complications (1.87%), of which a severe haemorrhage from a bronchial artery, a tracheal rupture, and a massive haemorrhage from an innominate artery laceration. In this 3 cases, the diagnosis were lung cancer in 2 patients and lymphoma in the other one. There were no intraoperative deaths. One patient died in the postoperative period due to mediastinitis and disease progression. The patient who suffered innominate artery laceration, had a stroke due to dissection of the right carotid artery. During follow-up, one patient died from progression of oncologic disease, and the other one is alive 4 years later. CONCLUSION: Although mediastinoscopy has a low rate of complications, these can be potentially lethal and the thoracic surgeon should be able to resolve them rapidly. Due to the scarcity of publications on this subject, it is important to describe potential complications of this surgical procedure and their clinical resolution.

Severe Intraoperative Complications During VATS Anatomical Ressections and their Surgical Resolution in a Portuguese Thoracic Surgery Centre - A 9-Year Review.

INTRODUCTION: Many studies have demonstrated that video-assisted thoracoscopic surgery (VATS) is not only feasible and safe but is actually the approach chosen for an increasing number of pulmonary anatomic resections. There are however few studies reporting on severe intraoperative complications during VATS anatomical ressections and their resolution. OBJECTIVE: Our aim is to analyse the incidence of severe intraoperative complications during VATS anatomical ressections, at our department, in the past nine years, and describe their technical resolution during the surgery. METHODS: We performed the retrospective analysis of the patients submitted to lobectomy, bilobectomy or segmentectomy by VATS or VATS converted to thoracotomy at Hospital de Santa Marta, between May 2008 and September 2017. Severe intraoperative complications were defined as an event that results in a life threatening situation or an injury to a proximal airway, blood vessel or organ that would lead to an unplanned additional anatomical resection. RESULTS: A total of 151 patients were submitted to anatomical ressections, 90,7% (n=137) of them for a primary lung cancer, other indications were metastatic disease 6%(n=9) and benign disease in 3,3% (n=5). The surgery was a lobectomy in 94% of the cases (n=142), a segmentectomy in 5% (n=8), and one bilobectomy. The conversion rate to thoracotomy was 12% (n=18), most of which were for technical/ oncological reasons (n=11), and 7 others were to control bleeding. Four (2,6%) severe intraoperative complications were identified. Three of them (2%) were erroneous transections of bronchovascular structures (left main bronchus, left main pulmonary artery and both left pulmonary veins); and one was a membranous airway injury proximal to the staple line. There were no intraoperative deaths. The three patients with erroneous bronchovascular transection were converted to thoracotomy and the bronchial or vascular re-anastomosis was performed, therefore avoiding a left pneumonectomy. In the patient with the membranous airway injury, the bronchoplastic suture was performed by VATS. All four patients were primary lung cancer patients. In all these cases the patients were discharged alive and well and are undergoing their follow-up program with no signs of disease recurrence. CONCLUSION: Albeit rare, severe complications during VATS Lobectomy can occur but when they happen the thoracic surgeon has to be ready to solve them with the minimal repercussion for the patient.

Glycosylation: impact, control and improvement during therapeutic protein production.

The emergence of the biopharmaceutical industry represented a major revolution for modern medicine, through the development of recombinant therapeutic proteins that brought new hope for many patients with previously untreatable diseases. There is a ever-growing demand for these therapeutics that forces a constant technological evolution to increase product yields while simultaneously reducing costs. However, the process changes made for this purpose may also affect the quality of the product, a factor that was initially overlooked but which is now a major focus of concern. Of the many properties determining product quality, glycosylation is regarded as one of the most important, influencing, for example, the biological activity, serum half-life and immunogenicity of the protein. Consequently, monitoring and control of glycosylation is now critical in biopharmaceutical manufacturing and a requirement of regulatory agencies. A rapid evolution is being observed in this context, concerning the influence of glycosylation in the efficacy of different therapeutic proteins, the impact on glycosylation of a diversity of parameters/processes involved in therapeutic protein production, the analytical methodologies employed for glycosylation monitoring and control, as well as strategies that are being explored to use this property to improve therapeutic protein efficacy (glycoengineering). This work reviews the main findings on these subjects, providing an up-to-date source of information to support further studies.

How do opioids control pain circuits in the brainstem during opioid-induced disorders and in chronic pain? Implications for the treatment of chronic pain.

ABSTRACT: Brainstem areas involved in descending pain modulation are crucial for the analgesic actions of opioids. However, the role of opioids in these areas during tolerance, opioid-induced hyperalgesia (OIH), and in chronic pain settings remains underappreciated. We conducted a revision of the recent studies performed in the main brainstem areas devoted to descending pain modulation with a special focus on the medullary dorsal reticular nucleus (DRt), as a distinctive pain facilitatory area and a key player in the diffuse noxious inhibitory control paradigm. We show that maladaptive processes within the signaling of the µ-opioid receptor (MOR), which entail desensitization and a switch to excitatory signaling, occur in the brainstem, contributing to tolerance and OIH. In the context of chronic pain, the alterations found are complex and depend on the area and model of chronic pain. For example, the downregulation of MOR and δ-opioid receptor (DOR) in some areas, including the DRt, during neuropathic pain likely contributes to the inefficacy of opioids. However, the upregulation of MOR and DOR, at the rostral ventromedial medulla, in inflammatory pain models, suggests therapeutic avenues to explore. Mechanistically, the rationale for the diversity and complexity of alterations in the brainstem is likely provided by the alternative splicing of opioid receptors and the heteromerization of MOR. In conclusion, this review emphasizes how important it is to consider the effects of opioids at these circuits when using opioids for the treatment of chronic pain and for the development of safer and effective opioids.

Synthetic Biology to Engineer Bacteriophage Genomes.

Recent advances in the synthetic biology field have enabled the development of new molecular biology techniques used to build specialized bacteriophages with new functionalities. Bacteriophages have been engineered toward a wide range of applications, including pathogen control and detection, targeted drug delivery, or even assembly of new materials.In this chapter, two strategies that have been successfully used to genetically engineer bacteriophage genomes will be addressed: the bacteriophage recombineering of electroporated DNA (BRED) and the yeast-based phage-engineering platform.