Industrial biotechnology of Pseudomonas putida: advances and prospects

Pseudomonas putida is a Gram-negative, rod-shaped bacterium that can be encountered in diverse ecological habitats. This ubiquity is traced to its remarkably versatile metabolism, adapted to withstand physicochemical stress, and the capacity to thrive in harsh environments. Owing to these characteristics, there is a growing interest in this microbe for industrial use, and the corresponding research has made rapid progress in recent years. Hereby, strong drivers are the exploitation of cheap renewable feedstocks and waste streams to produce value-added chemicals and the steady progress in genetic strain engineering and systems biology understanding of this bacterium. Here, we summarize the recent advances and prospects in genetic engineering, systems and synthetic biology, and applications of P. putida as a cell factory. KEY POINTS: • Pseudomonas putida advances to a global industrial cell factory. • Novel tools enable system-wide understanding and streamlined genomic engineering. • Applications of P. putida range from bioeconomy chemicals to biosynthetic drugs.

Versatile in vitro assay to recognize Cas9-induced mutations

The discovery of CRISPR/Cas9 has revolutionized molecular biology, and its impact on plant biotechnology and plant breeding cannot be over-estimated. In many plant species, its application for mutagenesis is now a routine procedure--if suitable target sites, sufficient expression of the Cas9 protein, and functioning sgRNAs are combined. sgRNAs differ in their efficiency, depending on parameters that are only poorly understood. Several software tools and experience from growing databases are supporting the design of sgRNAs, but some seemingly perfect sgRNAs turn out to be inefficient or fail entirely, and most data bases stem from work with mammalian cells. Different in vitro assays testing sgRNAs in reconstituted Cas9 complexes are available and useful to reduce the risk of failure, especially in plants when CRISPR/Cas9 application requires modifications within the germ line and laborious transformation protocols. Low sgRNA efficiency and long generation times in plants can also contribute to the workload and costs of screening for the wanted genome edits. Here, we present a protocol in which a simple, initial in vitro test for suitable sgRNAs is modified to accelerate genotyping of Cas9-induced mutations. We demonstrate applicability of our protocol for mutagenesis and mutation screen for specific genes in Arabidopsis, but the principle should be universally suitable to provide a simple, low-cost, and rapid method to identify edited genes also in other plants and other organisms.

New and alternative strategies for the prevention, control, and treatment of antibiotic-resistant Campylobacter

Campylobacter is an enteric pathogen and a leading bacterial cause of diarrhea worldwide. It is widely distributed in food animal species and is transmitted to humans primarily through the foodborne route. While generally causing self-limited diarrhea in humans, Campylobacter may induce severe or systemic infections in immunocompromised or young/elderly patients, which often requires antibiotic therapy with the first-line antibiotics including fluoroquinolones and macrolides. Over the past decades, Campylobacter has acquired resistance to these clinically significant antibiotics, compromising the effectiveness of antibiotic treatments. To address this concern, many studies have been conducted to advance novel and alternative measures to control antibiotic-resistant Campylobacter in animal reservoirs and in the human host. Although some of these undertakings have yielded promising results, efficacious and reliable alternative approaches are yet to be developed. In this review article, we will describe Campylobacter-associated disease spectrums and current treatment options, discuss the state of antibiotic resistance and alternative therapies, and provide an evaluation of various approaches that are being developed to control Campylobacter infections in animal reservoirs and the human host.

The Use of Ripple Effect Mapping to Understand Successes of the SC Pregnancy Assistance Fund: A Participatory Evaluation Approach

OBJECTIVES

The South Carolina Pregnancy Assistance Fund (SCPAF) funded four counties to increase the amount, quality, and awareness of services for young parents; increase educational attainment among expectant and parenting youth; reduce the number of repeat teen pregnancies among youth; and improve parenting skills. The purpose of this paper is twofold: (1) to describe our application of the Ripple Effect Mapping (REM) technique as an innovative evaluation strategy to gather perspectives from SCPAF stakeholders and (2) to share key findings generated by participants in REM sessions on the perceived success of local SCPAF community collaboratives.

METHODS

REM, an innovative evaluation strategy, was used to gather perspectives from SCPAF stakeholders. Five REM sessions were conducted with 52 participants. REM sessions included partner interviews and collective development of visual maps to illustrate stakeholder perspectives of program successes. Visual maps, as well as transcripts of discussions, were analyzed using an inductive approach.

RESULTS

Stakeholders reported that the connections to resources, supports, and services provided through SCPAF had the potential to alter the life trajectories of expectant and parenting teens (EPT). Stakeholders also described that SCPAF fostered growth in collaboration among partners and reduced duplication of services in funded communities CONCLUSIONS FOR PRACTICE: This paper describes how an innovative evaluation strategy was used to provide a space for stakeholders to dialogue, synthesize their experiences, and construct a collective narrative of key program successes. This paper also illustrates how such approaches can be applied to complex community initiatives.

Antioxidative and Antiglycative Properties of Mycosporine-Like Amino Acids-Containing Aqueous Extracts Derived from Edible Terrestrial Cyanobacteria

The terrestrial filamentous cyanobacterium, Nostoc commune, has been used as a food source in many countries, especially countries in Asia. In this study, N. commune-derived aqueous extracts were evaluated with regard to their antioxidative and antiglycative properties. The antioxidative activity was significantly higher in N. commune colonies isolated from the field than in extracts from colonies cultured in the laboratory. The antioxidative compound content of extracts, including phenolic compounds and phycobiliproteins, was correlated with their antioxidative power. In addition, two mycosporine-like amino acids (MAAs), specifically detected in colonies isolated from the field, were purified. In addition to assessing their antioxidative properties, the antiglycative activity of these MAAs was also assessed. Their inhibitory effects on glycation-dependent protein cross-linking might contribute to the antiglycative power of the extract prepared from field colonies. Taken together, the results from this study revealed that N. commune may have beneficial properties for functional food applications, both by preventing oxidative stress and suppressing the formation of advanced glycation end-products.

DeepCGH: 3D computer-generated holography using deep learning

The goal of computer-generated holography (CGH) is to synthesize custom illumination patterns by modulating a coherent light beam. CGH algorithms typically rely on iterative optimization with a built-in trade-off between computation speed and hologram accuracy that limits performance in advanced applications such as optogenetic photostimulation. We introduce a non-iterative algorithm, DeepCGH, that relies on a convolutional neural network with unsupervised learning to compute accurate holograms with fixed computational complexity. Simulations show that our method generates holograms orders of magnitude faster and with up to 41% greater accuracy than alternate CGH techniques. Experiments in a holographic multiphoton microscope show that DeepCGH substantially enhances two-photon absorption and improves performance in photostimulation tasks without requiring additional laser power.

Phage Display Derived Monoclonal Antibodies: From Bench to Bedside

Monoclonal antibodies (mAbs) have become one of the most important classes of biopharmaceutical products, and they continue to dominate the universe of biopharmaceutical markets in terms of approval and sales. They are the most profitable single product class, where they represent six of the top ten selling drugs. At the beginning of the 1990s, an in vitro antibody selection technology known as antibody phage display was developed by John McCafferty and Sir. Gregory Winter that enabled the discovery of human antibodies for diverse applications, particularly antibody-based drugs. They created combinatorial antibody libraries on filamentous phage to be utilized for generating antigen specific antibodies in a matter of weeks. Since then, more than 70 phage–derived antibodies entered clinical studies and 14 of them have been approved. These antibodies are indicated for cancer, and non-cancer medical conditions, such as inflammatory, optical, infectious, or immunological diseases. This review will illustrate the utility of phage display as a powerful platform for therapeutic antibodies discovery and describe in detail all the approved mAbs derived from phage display.

Interleukin-1β Drives Cellular Senescence of Rat Astrocytes Induced by Oligomerized Amyloid β Peptide and Oxidative Stress

Background: Alzheimer's disease (AD) is the leading cause of dementia. With no reliable treatment that delays or reverses the progress of AD, effective medical drugs, and interventions for AD treatment are in urgent need. Clinical success for patients thus relies on gaining a clearer understanding of AD pathogenesis to feed the development of novel and potent therapy strategies. It is well-established that inflammatory processes are involved in the pathology of AD, and recent studies implicated senescence of glial cells as an important player in the progression of AD.

Methods: We did a preliminary screen in rat astrocytes for the five most abundant inflammatory factors in neuroinflammation, namely IL-1β, IL-6, IL-8, TGF-β1, and TNF-α, and found that IL-1β could efficiently induce cellular senescence. After that, SA-β-gal staining, immunofluorescence, ELISA, qRT-PCR, and immunoblotting were used to explore the underlying mechanism through which IL-1β mediates cellular senescence of rat astrocytes.

Results: IL-1β-induced cellular senescence of rat astrocytes was accompanied by increased total and phosphorylated tau. Further experiments showed that both oligomerized amyloid β (Aβ) and H₂O₂ treatment can induce cellular senescence in rat astrocytes and increase the production and secretion of IL-1β from these cells. Subsequent mechanistic study revealed that activation of NLRP3 mediates Aβ and H₂O₂-induced maturation and secretion of IL-1β.

Conclusion: Our results suggest that IL-1β mediates senescence in rat astrocytes induced by several common adverse stimuli in AD, implicating IL-1β and NLRP3 as valuable diagnostic biomarkers and therapeutic targets for AD.

Review: Cantilever-Based Sensors for High Speed Atomic Force Microscopy

This review critically summarizes the recent advances of the microcantilever-based force sensors for atomic force microscope (AFM) applications. They are one the most common mechanical spring-mass systems and are extremely sensitive to changes in the resonant frequency, thus finding numerous applications especially for molecular sensing. Specifically, we comment on the latest progress in research on the deflection detection systems, fabrication, coating and functionalization of the microcantilevers and their application as bio- and chemical sensors. A trend on the recent breakthroughs on the study of biological samples using high-speed atomic force microscope is also reported in this review.

Bringing Light into Cell-Free Expression

Cell-free systems, as part of the synthetic biology field, have become a critical platform in biological studies. However, there is a lack of research into developing a switch for a dynamical control of the transcriptional and translational process. The optogenetic tool has been widely proven as an ideal control switch for protein synthesis due to its nontoxicity and excellent time-space conversion. Hence, in this study, a blue light-regulated two-component system named YF1/FixJ was incorporated into an Escherichia coli-based cell-free system to control protein synthesis. The corresponding cell-free system successfully achieved a 5-fold dynamic protein expression by blue light repression and 3-fold dynamic expression by blue light activation. With the aim of expanding the applications of cell-free synthetic biology, the cell-free blue light-sensing system was used to perform imaging, light-controlled antibody synthesis, and light-triggered artificial cell assembly. This study can provide a guide for further research into the field of cell-free optical sensing. Moreover, it will also promote the development of cell-free synthetic biology and optogenetics through applying the cell-free optical sensing system to synthetic biology education, biopharmaceutical research, and artificial cell construction.

A Cell-Free Protein Expression System Derived from Human Primary Peripheral Blood Mononuclear Cells

Historically, some of the first cell-free protein expression systems studied in vitro translation in various human blood cells. However, because of limited knowledge of eukaryotic translation and the advancement of cell line development, interest in these systems decreased. Eukaryotic translation is a complex system of factors that contribute to the overall translation of mRNA to produce proteins. The intracellular translateome of a cell can be modified by various factors and disease states, but it is impossible to individually measure all factors involved when there is no comprehensive understanding of eukaryotic translation. The present work outlines the use of a coupled transcription and translation cell-free protein expression system to produce recombinant proteins derived from human donor peripheral blood mononuclear cells (PBMCs) activated with phytohemagglutinin-M (PHA-M). The methods outlined here could result in tools to aid immunology, gene therapy, cell therapy, and synthetic biology research and provide a convenient and holistic method to study and assess the intracellular translation environment of primary immune cells.

Metastasis Model of Cancer Stem Cell-Derived Tumors

Metastasis includes the dissemination of cancer cells from a malignant tumor and seed in distant sites inside the body forming secondary tumors. Metastatic cells from the primary tumor can move even before the cancer is detected. Therefore, metastases are responsible for more than 90% of cancer-related deaths. Over recent decades there has been adequate evidence suggesting the existence of CSCs with self-renewing and drug-resistant potency within heterogeneous tumors. Cancer stem cells (CSCs) act as a tumor initiating cells and have roles in tumor retrieve and metastasis. Our group recently developed a unique CSC model from mouse induced pluripotent stem cells cultured in the presence of cancer cell-conditioned medium that mimics tumors microenvironment. Using this model, we demonstrated a new method for studying metastasis by intraperitoneal transplantation of tumors and investigate the metastasis ability of cells from these segments. First of all, CSCs were injected subcutaneously in nude mice. The developed malignant tumors were minimized then transplanted into the peritoneal cavity. Following this, the developed tumor in addition to lung, pancreas and liver were then excised and analyzed. Our method showed the metastatic potential of CSCs with the ability of disseminated and moving to blood circulation and seeding in distant organs such as lung and pancreas. This method could provide a good model to study the mechanisms of metastasis according to CSC theory.

Chromene- and Quinoline-3-Carbaldehydes: Useful Intermediates in the Synthesis of Heterocyclic Scaffolds

Chromenes and quinolines are recognized as important scaffolds in medicinal chemistry. Herein, the efficient use of chromene- and quinoline-3-carbaldehydes to synthesize other valuable heterocycles is described. These carbaldehydes are obtained in excellent yields through the Vilsmeyer-Haack reaction of flavanones and azaflavanones. Protocols towards the synthesis of new heterocycles, such as 3H-chromeno[3–c]quinolines, (Z/E)-2-aryl-4-chloro-3-styryl-2H-chromenes, and (E)-2-aryl-4-chloro-3-styrylquinoline-1(2H)-carbaldehydes were established. Altogether, we demonstrate the value of chromene- and quinoline-3-carbaldehydes as building blocks.

The Genetic Code Kit: An Open-Source Cell-Free Platform for Biochemical and Biotechnology Education

Teaching the processes of transcription and translation is challenging due to the intangibility of these concepts and a lack of instructional, laboratory-based, active learning modules. Harnessing the genetic code in vitro with cell-free protein synthesis (CFPS) provides an open platform that allows for the direct manipulation of reaction conditions and biological machinery to enable inquiry-based learning. Here, we report our efforts to transform the research-based CFPS biotechnology into a hands-on module called the “Genetic Code Kit” for implementation into teaching laboratories. The Genetic Code Kit includes all reagents necessary for CFPS, as well as a laboratory manual, student worksheet, and augmented reality activity. This module allows students to actively explore transcription and translation while gaining exposure to an emerging research technology. In our testing of this module, undergraduate students who used the Genetic Code Kit in a teaching laboratory showed significant score increases on transcription and translation questions in a post-lab questionnaire compared with students who did not participate in the activity. Students also demonstrated an increase in self-reported confidence in laboratory methods and comfort with CFPS, indicating that this module helps prepare students for careers in laboratory research. Importantly, the Genetic Code Kit can accommodate a variety of learning objectives beyond transcription and translation and enables hypothesis-driven science. This opens the possibility of developing Course-Based Undergraduate Research Experiences (CUREs) based on the Genetic Code Kit, as well as supporting next-generation science standards in 8–12th grade science courses.

Host-microbiota-insect interactions drive emergent virulence in a complex tree disease

Forest declines caused by climate disturbance, insect pests and microbial pathogens threaten the global landscape, and tree diseases are increasingly attributed to the emergent properties of complex ecological interactions between the host, microbiota and insects. To address this hypothesis, we combined reductionist approaches (single and polyspecies bacterial cultures) with emergentist approaches (bacterial inoculations in an oak infection model with the addition of insect larvae) to unravel the gene expression landscape and symptom severity of host-microbiota-insect interactions in the acute oak decline (AOD) pathosystem. AOD is a complex decline disease characterized by predisposing abiotic factors, inner bark lesions driven by a bacterial pathobiome, and larval galleries of the bark-boring beetle Agrilus biguttatus. We identified expression of key pathogenicity genes in Brenneria goodwinii, the dominant member of the AOD pathobiome, tissue-specific gene expression profiles, cooperation with other bacterial pathobiome members in sugar catabolism, and demonstrated amplification of pathogenic gene expression in the presence of Agrilus larvae. This study highlights the emergent properties of complex host-pathobiota-insect interactions that underlie the pathology of diseases that threaten global forest biomes.

Oleic Acid, Cholesterol, and Linoleic Acid as Angiogenesis Initiators

The current study determined the natural angiogenic molecules using an unbiased metabolomics approach. A chick chorioallantoic membrane (CAM) model was used to examine pro- and antiangiogenic molecules, followed by gas chromatography-mass spectrometry (GCMS) analysis. Vessel formation was analyzed quantitatively using the angiogenic index (p < 0.05). At embryonic day one, a white streak or circle area was observed when vessel formation begins. GCMS analysis and database search demonstrated that angiogenesis may initiate when oleic, cholesterol, and linoleic acids increased in the area of angiogenic reactions. The gain of function study was conducted by the injection of cholesterol and oleic acid into a chick embryo to determine the role of each lipid in angiogenesis. We propose that oleic acid, cholesterol, and linoleic acid are natural molecules that set the platform for the initiation stage of angiogenesis before other proteins including the vascular endothelial growth factor, angiopoietin, angiotensin, and erythropoietin join as the angiome in sprout extension and vessel maturation.

Vagus nerve stimulation paired with tones restores auditory processing in a rat model of Rett syndrome

BACKGROUND

Rett syndrome is a rare neurological disorder associated with a mutation in the X-linked gene MECP2. This disorder mainly affects females, who typically have seemingly normal early development followed by a regression of acquired skills. The rodent Mecp2 model exhibits many of the classic neural abnormalities and behavioral deficits observed in individuals with Rett syndrome. Similar to individuals with Rett syndrome, both auditory discrimination ability and auditory cortical responses are impaired in heterozygous Mecp2 rats. The development of therapies that can enhance plasticity in auditory networks and improve auditory processing has the potential to impact the lives of individuals with Rett syndrome. Evidence suggests that precisely timed vagus nerve stimulation (VNS) paired with sound presentation can drive robust neuroplasticity in auditory networks and enhance the benefits of auditory therapy.

OBJECTIVE

The aim of this study was to investigate the ability of VNS paired with tones to restore auditory processing in Mecp2 transgenic rats.

METHODS

Seventeen female heterozygous Mecp2 rats and 8 female wild-type (WT) littermates were used in this study. The rats were exposed to multiple tone frequencies paired with VNS 300 times per day for 20 days. Auditory cortex responses were then examined following VNS-tone pairing therapy or no therapy.

RESULTS

Our results indicate that Mecp2 mutation alters auditory cortex responses to sounds compared to WT controls. VNS-tone pairing in Mecp2 rats improves the cortical response strength to both tones and speech sounds compared to untreated Mecp2 rats. Additionally, VNS-tone pairing increased the information contained in the neural response that can be used to discriminate between different consonant sounds.

CONCLUSION

These results demonstrate that VNS-sound pairing may represent a strategy to enhance auditory function in individuals with Rett syndrome.

SILEX: a fast and inexpensive high-quality DNA extraction method suitable for multiple sequencing platforms and recalcitrant plant species

BACKGROUND

The use of sequencing and genotyping platforms has undergone dramatic improvements, enabling the generation of a wealth of genomic information. Despite this progress, the availability of high-quality genomic DNA (gDNA) in sufficient concentrations is often a main limitation, especially for third-generation sequencing platforms. A variety of DNA extraction methods and commercial kits are available. However, many of these are costly and frequently give either low yield or low-quality DNA, inappropriate for next generation sequencing (NGS) platforms. Here, we describe a fast and inexpensive DNA extraction method (SILEX) applicable to a wide range of plant species and tissues.

RESULTS

SILEX is a high-throughput DNA extraction protocol, based on the standard CTAB method with a DNA silica matrix recovery, which allows obtaining NGS-quality high molecular weight genomic plant DNA free of inhibitory compounds. SILEX was compared with a standard CTAB extraction protocol and a common commercial extraction kit in a variety of species, including recalcitrant ones, from different families. In comparison with the other methods, SILEX yielded DNA in higher concentrations and of higher quality. Manual extraction of 48 samples can be done in 96 min by one person at a cost of 0.12 €/sample of reagents and consumables. Hundreds of tomato gDNA samples obtained with either SILEX or the commercial kit were successfully genotyped with Single Primer Enrichment Technology (SPET) with the Illumina HiSeq 2500 platform. Furthermore, DNA extracted from Solanum elaeagnifolium using this protocol was assessed by Pulsed-field gel electrophoresis (PFGE), obtaining a suitable size ranges for most sequencing platforms that required high-molecular-weight DNA such as Nanopore or PacBio.

CONCLUSIONS

A high-throughput, fast and inexpensive DNA extraction protocol was developed and validated for a wide variety of plants and tissues. SILEX offers an easy, scalable, efficient and inexpensive way to extract DNA for various next-generation sequencing applications including SPET and Nanopore among others.

Transfection of hPSC-Cardiomyocytes Using Viafect™ Transfection Reagent

Twenty years since their first derivation, human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have shown promise in disease modelling research, while their potential for cardiac repair is being investigated. However, low transfection efficiency is a barrier to wider realisation of the potential this model system has to offer. We endeavoured to produce a protocol for improved transfection of hPSC-CMs using the ViafectTM reagent by Promega. Through optimisation of four essential parameters: (i) serum supplementation, (ii) time between replating and transfection, (iii) reagent to DNA ratio and (iv) cell density, we were able to successfully transfect hPSC-CMs to ~95% efficiencies. Transfected hPSC-CMs retained high purity and structural integrity despite a mild reduction in viability, and preserved compatibility with phenotyping assays of hypertrophy. This protocol greatly adds value to the field by overcoming limited transfection efficiencies of hPSC-CMs in a simple and quick approach that ensures sustained expression of transfected genes for at least 14 days, opening new opportunities in mechanistic discovery for cardiac-related diseases.

The Isolation and Genome Sequencing of Five Novel Bacteriophages From the Rumen Active Against Butyrivibrio fibrisolvens

Although the prokaryotic communities of the rumen microbiome are being uncovered through genome sequencing, little is known about the resident viral populations. Whilst temperate phages can be predicted as integrated prophages when analyzing bacterial and archaeal genomes, the genetics underpinning lytic phages remain poorly characterized. To the five genomes of bacteriophages isolated from rumen-associated samples sequenced and analyzed previously, this study adds a further five novel genomes and predictions gleaned from them to further the understanding of the rumen phage population. Lytic bacteriophages isolated from fresh ovine and bovine fecal and rumen fluid samples were active against the predominant fibrolytic ruminal bacterium Butyrivibrio fibrisolvens. The double stranded DNA genomes were sequenced and reconstructed into single circular complete contigs. Based on sequence similarity and genome distances, the five phages represent four species from three separate genera, consisting of: (1) Butyrivibrio phages Arian and Bo-Finn; (2) Butyrivibrio phages Idris and Arawn; and (3) Butyrivibrio phage Ceridwen. They were predicted to all belong to the Siphoviridae family, based on evidence in the genomes such as size, the presence of the tail morphogenesis module, genes that share similarity to those in other siphovirus isolates and phylogenetic analysis using phage proteomes. Yet, phylogenomic analysis and sequence similarity of the entire phage genomes revealed that these five phages are unique and novel. These phages have only been observed undergoing the lytic lifecycle, but there is evidence in the genomes of phages Arawn and Idris for the potential to be temperate. However, there is no evidence in the genome of the bacterial host Butyrivibrio fibrisolvens of prophage genes or genes that share similarity with the phage genomes.

MDM2-Dependent Rewiring of Metabolomic and Lipidomic Profiles in Dedifferentiated Liposarcoma Models

Dedifferentiated liposarcoma (DDLPS) is an aggressive mesenchymal cancer marked by amplification of MDM2, an inhibitor of the tumor suppressor TP53. DDLPS patients with higher MDM2 amplification have lower chemotherapy sensitivity and worse outcome than patients with lower MDM2 amplification. We hypothesized that MDM2 amplification levels may be associated with changes in DDLPS metabolism. Six patient-derived DDLPS cell line models were subject to comprehensive metabolomic (Metabolon) and lipidomic (SCIEX 5600 TripleTOF-MS) profiling to assess associations with MDM2 amplification and their responses to metabolic perturbations. Comparing metabolomic profiles between MDM2 higher and lower amplification cells yielded a total of 17 differentially abundant metabolites across both panels (FDR < 0.05, log2 fold change < 0.75), including ceramides, glycosylated ceramides, and sphingomyelins. Disruption of lipid metabolism through statin administration resulted in a chemo-sensitive phenotype in MDM2 lower cell lines only, suggesting that lipid metabolism may be a large contributor to the more aggressive nature of MDM2 higher DDLPS tumors. This study is the first to provide comprehensive metabolomic and lipidomic characterization of DDLPS cell lines and provides evidence for MDM2-dependent differential molecular mechanisms that are critical factors in chemoresistance and could thus affect patient outcome.

Fucoidan functionalization on poly(vinyl alcohol) hydrogels for improved endothelialization and hemocompatibility

The performance of clinical synthetic small diameter vascular grafts remains disappointing due to the fast occlusion caused by thrombosis and intimal hyperplasia formation. Poly(vinyl alcohol) (PVA) hydrogels have tunable mechanical properties and a low thrombogenic surface, which suggests its potential value as a small diameter vascular graft material. However, PVA does not support cell adhesion and thus requires surface modification to encourage endothelialization. This study presents a modification of PVA with fucoidan. Fucoidan is a sulfated polysaccharide with anticoagulant and antithrombotic properties, which was shown to potentially increase endothelial cell adhesion and proliferation. By mixing fucoidan with PVA and co-crosslinked by sodium trimetaphosphate (STMP), the modification was achieved without sacrificing mechanical properties. Endothelial cell adhesion and monolayer function were significantly enhanced by the fucoidan modification. In vitro and ex-vivo studies showed low platelet adhesion and activation and decreased thrombin generation with fucoidan modified PVA. The modification proved to be compatible with gamma sterilization. In vivo evaluation of fucoidan modified PVA grafts in rabbits exhibited increased patency rate, endothelialization, and reduced intimal hyperplasia formation. The fucoidan modification presented here benefited the development of PVA vascular grafts and can be adapted to other blood contacting surfaces.

Frequency-doubled femtosecond Er-doped fiber laser for two-photon excited fluorescence imaging

A femtosecond frequency-doubled erbium-doped fiber laser with an adjustable pulse repetition rate is developed and applied in two-photon excited fluorescence microscopy. The all-fiber laser system provides the fundamental pulse at 1560 nm wavelength with 22 fs duration for the second harmonic generation, resulting in 1.35 nJ, 60 fs pulses at 780 nm. The repetition rate is adjusted by a pulse picker unit built-in within the amplifier chain, directly providing transform-limited pulses for any chosen repetition rate between 1 and 12 MHz. We employed the laser source to drive a scanning two-photon excited fluorescence microscope for ex vivo rat skin and other samples' imaging at various pulse repetition rates. Due to compactness, ease of operation, and suitable pulse characteristics, the laser source can be considered as an attractive alternative for Ti:Sapphire laser in biomedical imaging.

Synthetic circular miR-21 RNA decoys enhance tumor suppressor expression and impair tumor growth in mice

Naturally occurring circular RNAs efficiently impair miRNA functions. Synthetic circular RNAs may thus serve as potent agents for miRNA inhibition. Their therapeutic effect critically relies on (i) the identification of optimal miRNA targets, (ii) the optimization of decoy structures and (iii) the development of efficient formulations for their use as drugs. In this study, we extensively explored the functional relevance of miR-21-5p in cancer cells. Analyses of cancer transcriptomes reveal that miR-21-5p is the by far most abundant miRNA in human cancers. Deletion of the MIR21 locus in cancer-derived cells identifies several direct and indirect miR-21-5p targets, including major tumor suppressors with prognostic value across cancers. To impair miR-21-5p activities, we evaluate synthetic, circular RNA decoys containing four repetitive binding elements. In cancer cells, these decoys efficiently elevate tumor suppressor expression and impair tumor cell vitality. For their in vivo delivery, we for the first time evaluate the formulation of decoys in polyethylenimine (PEI)-based nanoparticles. We demonstrate that PEI/decoy nanoparticles lead to a significant inhibition of tumor growth in a lung adenocarcinoma xenograft mouse model via the upregulation of tumor suppressor expression. These findings introduce nanoparticle-delivered circular miRNA decoys as a powerful potential therapeutic strategy in cancer treatment.

Effect of an Enhanced Self-Care Protocol on Lymphedema Status among People Affected by Moderate to Severe Lower-Limb Lymphedema in Bangladesh, a Cluster Randomized Controlled Trial

Background: Lymphatic filariasis (LF) is a major cause of lymphedema, affecting over 16 million people globally. A daily, hygiene-centered self-care protocol is recommended and effective in reducing acute attacks caused by secondary infections. It may also reverse lymphedema status in early stages, but less so as lymphedema advances. Lymphatic stimulating activities such as self-massage and deep-breathing have proven beneficial for cancer-related lymphedema, but have not been tested in LF-settings. Therefore, an enhanced self-care protocol was trialed among people affected by moderate to severe LF-related lymphedema in northern Bangladesh. Methods: Cluster randomization was used to allocate participants to either standard- or enhanced-self-care groups. Lymphedema status was determined by lymphedema stage, mid-calf circumference, and mid-calf tissue compressibility. Results: There were 71 patients in each group and at 24 weeks, both groups had experienced significant improvement in lymphedema status and reduction in acute attacks. There was a significant and clinically relevant between-group difference in mid-calf tissue compressibility with the biggest change observed on legs affected by severe lymphedema in the enhanced self-care group (∆ 21.5%, −0.68 (−0.91, −0.45), p < 0.001). Conclusion: This study offers the first evidence for including lymphatic stimulating activities in recommended self-care for people affected by moderate and severe LF-related lymphedema.

Cell-Free Synthetic Glycobiology: Designing and Engineering Glycomolecules Outside of Living Cells

Glycans and glycosylated biomolecules are directly involved in almost every biological process as well as the etiology of most major diseases. Hence, glycoscience knowledge is essential to efforts aimed at addressing fundamental challenges in understanding and improving human health, protecting the environment and enhancing energy security, and developing renewable and sustainable resources that can serve as the source of next-generation materials. While much progress has been made, there remains an urgent need for new tools that can overexpress structurally uniform glycans and glycoconjugates in the quantities needed for characterization and that can be used to mechanistically dissect the enzymatic reactions and multi-enzyme assembly lines that promote their construction. To address this technology gap, cell-free synthetic glycobiology has emerged as a simplified and highly modular framework to investigate, prototype, and engineer pathways for glycan biosynthesis and biomolecule glycosylation outside the confines of living cells. From nucleotide sugars to complex glycoproteins, we summarize here recent efforts that harness the power of cell-free approaches to design, build, test, and utilize glyco-enzyme reaction networks that produce desired glycomolecules in a predictable and controllable manner. We also highlight novel cell-free methods for shedding light on poorly understood aspects of diverse glycosylation processes and engineering these processes toward desired outcomes. Taken together, cell-free synthetic glycobiology represents a promising set of tools and techniques for accelerating basic glycoscience research (e.g., deciphering the "glycan code") and its application (e.g., biomanufacturing high-value glycomolecules on demand).

DNA extraction method influences human milk bacterial profiles

AIMS

To evaluate four DNA extraction methods to elucidate the most effective method for bacterial DNA recovery from human milk (HM).

METHODS AND RESULTS

Human milk DNA was extracted using the following methods: (i) Qiagen MagAttract Microbial DNA Isolation Kit (kit QM), (ii) Norgen Milk Bacterial DNA Isolation Kit (kit NM), (iii) Qiagen MagAttract Microbiome DNA/RNA Isolation Kit (kit MM) and (iv) TRIzol LS Reagent (method LS). The full-length 16S rRNA gene was sequenced. Kits MM and method LS were unable to extract detectable levels of DNA in 9/11 samples. Detectable levels of DNA were recovered from all samples using kits NM (mean = 0·68 ng μl^-1 ) and QM (mean = 0·55 ng μl^-1 ). For kits NM and QM, the greatest number of reads were associated with Staphylococcus epidermidis, Streptococcus vestibularis, Propionibacterium acnes, Veillonella dispar and Rothia mucilaginosa. Contamination profiles varied substantially between kits, with one bacterial species detected in negative extraction controls generated with kit QM and six with kit NM.

CONCLUSIONS

Kit QM is the most suitable of the kits tested for the extraction of bacterial DNA from human milk.

SIGNIFICANCE AND IMPACT OF THE STUDY

Choice of extraction method impacts the efficiency of bacterial DNA extraction from human milk and the resultant bacterial community profiles generated from these samples.

Cell-Free Systems: A Proving Ground for Rational Biodesign

Cell-free gene expression systems present an alternative approach to synthetic biology, where biological gene expression is harnessed inside non-living, in vitro biochemical reactions. Taking advantage of a plethora of recent experimental innovations, they easily overcome certain challenges for computer-aided biological design. For instance, their open nature renders all their components directly accessible, greatly facilitating model construction and validation. At the same time, these systems present their own unique difficulties, such as limited reaction lifetimes and lack of homeostasis. In this Perspective, I propose that cell-free systems are an ideal proving ground to test rational biodesign strategies, as demonstrated by a small but growing number of examples of model-guided, forward engineered cell-free biosystems. It is likely that advances gained from this approach will contribute to our efforts to more reliably and systematically engineer both cell-free as well as living cellular systems for useful applications.

Announcing the Availability of a Culture Collection of Uranium-Resistant Microbial Assemblages (CURMA) Obtained from Metalliferous Soils of the Savannah River Site, USA

Metagenomic assessment provides a comprehensive survey of soil microbiota; however, isolation and characterization of functionally relevant microbiota are required prior to their application(s), such as for metal remediation. Toward this end, we report the availability of a culture collection comprising uranium (U)-resistant microbial assemblages (CURMA) to the scientific community.

Metagenomic assessment provides a comprehensive survey of soil microbiota; however, isolation and characterization of functionally relevant microbiota are required prior to their application(s), such as for metal remediation. Toward this end, we report the availability of a culture collection comprising uranium (U)-resistant microbial assemblages (CURMA) to the scientific community.

Mitochondrial DNA: Hotspot for Potential Gene Modifiers Regulating Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a prevalent and untreatable cardiovascular disease with a highly complex clinical and genetic causation. HCM patients bearing similar sarcomeric mutations display variable clinical outcomes, implying the involvement of gene modifiers that regulate disease progression. As individuals exhibiting mutations in mitochondrial DNA (mtDNA) present cardiac phenotypes, the mitochondrial genome is a promising candidate to harbor gene modifiers of HCM. Herein, we sequenced the mtDNA of isogenic pluripotent stem cell-cardiomyocyte models of HCM focusing on two sarcomeric mutations. This approach was extended to unrelated patient families totaling 52 cell lines. By correlating cellular and clinical phenotypes with mtDNA sequencing, potentially HCM-protective or -aggravator mtDNA variants were identified. These novel mutations were mostly located in the non-coding control region of the mtDNA and did not overlap with those of other mitochondrial diseases. Analysis of unrelated patients highlighted family-specific mtDNA variants, while others were common in particular population haplogroups. Further validation of mtDNA variants as gene modifiers is warranted but limited by the technically challenging methods of editing the mitochondrial genome. Future molecular characterization of these mtDNA variants in the context of HCM may identify novel treatments and facilitate genetic screening in cardiomyopathy patients towards more efficient treatment options.

Evaluation of the efficiency of using Salmonella Kentucky and Escherichia coli O119 bacteriophages in the treatment and prevention of salmonellosis and colibacillosis in broiler chickens

Phage therapy is considered an alternative modality in the treatment of different bacterial diseases. However, their therapeutic and preventive roles against infections caused by Salmonella Kentucky and Escherichia coli O119 were of little attention. In this study, two phages were isolated, characterized and assessed for their potential therapeutic and preventive roles against S. Kentucky and E. coli O119 infections in broilers. Commercial 1-day-old arboacres broiler chicks were assigned to seven groups: Group Ӏ was as a negative control, groups (П and Ш) were assigned as positive controls by the challenge of S. Kentucky and E. coli O119, respectively. The remaining four groups (IV, V, VI and VII) were administrated with five repeated phage doses to determine the effect of multiple doses. Phages were administrated in groups (IV and VI) after challenging with S. Kentucky and E. coli O119, respectively to assess their therapeutic role; moreover, their preventive role was evaluated through administration in groups (V and VII) before challenging with S. Kentucky and E. coli O119, respectively. Sampling was done from different organs at three time points and revealed that phage-treated groups had lower colony forming units of S. Kentucky and E. coli. Our results suggest that bacteriophages are efficient in the treatment and prevention of salmonellosis and colibacillosis in broiler farms.

Synthetic Glycobiology: Parts, Systems, and Applications

Protein glycosylation, the attachment of sugars to amino acid side chains, can endow proteins with a wide variety of properties of great interest to the engineering biology community. However, natural glycosylation systems are limited in the diversity of glycoproteins they can synthesize, the scale at which they can be harnessed for biotechnology, and the homogeneity of glycoprotein structures they can produce. Here we provide an overview of the emerging field of synthetic glycobiology, the application of synthetic biology tools and design principles to better understand and engineer glycosylation. Specifically, we focus on how the biosynthetic and analytical tools of synthetic biology have been used to redesign glycosylation systems to obtain defined glycosylation structures on proteins for diverse applications in medicine, materials, and diagnostics. We review the key biological parts available to synthetic biologists interested in engineering glycoproteins to solve compelling problems in glycoscience, describe recent efforts to construct synthetic glycoprotein synthesis systems, and outline exemplary applications as well as new opportunities in this emerging space.

Cell-free biology using remote-controlled digital microfluidics for individual droplet control

Cell-free biology for diverse protein expression and biodetection in vitro has developed rapidly in recent years because of its more open and controllable reaction environment. However, complex liquid handling schemes are troublesome, especially when scaling up to perform multiple different reactions simultaneously. Digital microfluidic (DMF) technology can operate a single droplet by controlling its movement, mixing, separation, and some other actions, and is a suitable scaffold for cell-free reactions with higher efficiency. In this paper, a commercial DMF board, OpenDrop, was used, and DMF technology via remote real-time control inspired by the Internet of Things (IoT) was developed for detecting glucose enzyme catalytic cell-free reactions and verifying the feasibility of programmed cell-free protein expression. A cell-free biological reaction process which can be remote-controlled visually with excellent interactivity, controllability and flexibility was achieved. As proof-of-concept research, this work proposed a new control interface for single-drop cell-free biological reactions. It is much like the "droplet operation desktop" concept, used for remote-controllable operations and distributions of cell-free biology for efficient biological screening and protein synthesis in complex reaction networks, with expanded operability and less artificial interference.

Antibacterial Activity of Bacteriocinogenic Commensal Escherichia coli against Zoonotic Strains Resistant and Sensitive to Antibiotics

Antibiotic resistance concerns various areas with high consumption of antibiotics, including husbandry. Resistant strains are transmitted to humans from livestock and agricultural products via the food chain and may pose a health risk. The commensal microbiota protects against the invasion of environmental strains by secretion of bacteriocins, among other mechanisms. The present study aims to characterize the bactericidal potential of bacteriocinogenic Escherichia coli from healthy humans against multidrug-resistant and antibiotic-sensitive strains from pigs and cattle. Bacteriocin production was tested by the double-layer plate method, and bacteriocin genes were identified by the PCR method. At least one bacteriocinogenic E. coli was detected in the fecal samples of 55% of tested individuals, adults and children. Among all isolates (n = 210), 37.1% were bacteriocinogenic and contained genes of colicin (Col) Ib, ColE1, microcin (Mcc) H47, ColIa, ColM, MccV, ColK, ColB, and single ColE2 and ColE7. Twenty-five E. coli carrying various sets of bacteriocin genes were further characterized and tested for their activity against zoonotic strains (n = 60). Strains with ColE7 (88%), ColE1-ColIa-ColK-MccH47 (85%), MccH47-MccV (85%), ColE1-ColIa-ColM (82%), ColE1 (75%), ColM (67%), and ColK (65%) were most active against zoonotic strains. Statistically significant differences in activity toward antibiotic-resistant strains were shown by commensal E. coli carrying MccV, ColK-MccV, and ColIb-ColK. The study demonstrates that bacteriocinogenic commensal E. coli exerts antagonistic activity against zoonotic strains and may constitute a defense line against multidrug-resistant strains.

Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications

Fast, high-resolution, non-destructive and quantitative characterization methods are needed to develop materials with tailored properties at the nanoscale or to understand the relationship between mechanical properties and cell physiology. This review introduces the state-of-the-art force microscope-based methods to map at high-spatial resolution the elastic and viscoelastic properties of soft materials. The experimental methods are explained in terms of the theories that enable the transformation of observables into material properties. Several applications in materials science, molecular biology and mechanobiology illustrate the scope, impact and potential of nanomechanical mapping methods.

Experimental and Computational Study on Motor Control and Recovery After Stroke: Toward a Constructive Loop Between Experimental and Virtual Embodied Neuroscience

Being able to replicate real experiments with computational simulations is a unique opportunity to refine and validate models with experimental data and redesign the experiments based on simulations. However, since it is technically demanding to model all components of an experiment, traditional approaches to modeling reduce the experimental setups as much as possible. In this study, our goal is to replicate all the relevant features of an experiment on motor control and motor rehabilitation after stroke. To this aim, we propose an approach that allows continuous integration of new experimental data into a computational modeling framework. First, results show that we could reproduce experimental object displacement with high accuracy via the simulated embodiment in the virtual world by feeding a spinal cord model with experimental registration of the cortical activity. Second, by using computational models of multiple granularities, our preliminary results show the possibility of simulating several features of the brain after stroke, from the local alteration in neuronal activity to long-range connectivity remodeling. Finally, strategies are proposed to merge the two pipelines. We further suggest that additional models could be integrated into the framework thanks to the versatility of the proposed approach, thus allowing many researchers to achieve continuously improved experimental design.

Monitoring Protein-Protein Interactions in the Cyanobacterial Circadian Clock in Real Time via Electron Paramagnetic Resonance Spectroscopy

The cyanobacterial circadian clock in Synechococcus elongatus consists of three proteins, KaiA, KaiB, and KaiC. KaiA and KaiB rhythmically interact with KaiC to generate stable oscillations of KaiC phosphorylation with a period of 24 h. The observation of stable circadian oscillations when the three clock proteins are reconstituted and combined in vitro makes it an ideal system for understanding its underlying molecular mechanisms and circadian clocks in general. These oscillations were historically monitored in vitro by gel electrophoresis of reaction mixtures based on the differing electrophoretic mobilities between various phosphostates of KaiC. As the KaiC phospho-distribution represents only one facet of the oscillations, orthogonal tools are necessary to explore other interactions to generate a full description of the system. However, previous biochemical assays are discontinuous or qualitative. To circumvent these limitations, we developed a spin-labeled KaiB mutant that can differentiate KaiC-bound KaiB from free KaiB using continuous-wave electron paramagnetic resonance spectroscopy that is minimally sensitive to KaiA. Similar to wild-type (WT-KaiB), this labeled mutant, in combination with KaiA, sustains robust circadian rhythms of KaiC phosphorylation. This labeled mutant is hence a functional surrogate of WT-KaiB and thus participates in and reports on autonomous macroscopic circadian rhythms generated by mixtures that include KaiA, KaiC, and ATP. Quantitative kinetics could be extracted with improved precision and time resolution. We describe design principles, data analysis, and limitations of this quantitative binding assay and discuss future research necessary to overcome these challenges.

A Critical Review of Bottom-Up Proteomics: The Good, the Bad, and the Future of this Field

Proteomics is the field of study that includes the analysis of proteins, from either a basic science prospective or a clinical one. Proteins can be investigated for their abundance, variety of proteoforms due to post-translational modifications (PTMs), and their stable or transient protein–protein interactions. This can be especially beneficial in the clinical setting when studying proteins involved in different diseases and conditions. Here, we aim to describe a bottom-up proteomics workflow from sample preparation to data analysis, including all of its benefits and pitfalls. We also describe potential improvements in this type of proteomics workflow for the future.

Probing the physio-chemical appraisal of green synthesized PbO nanoparticles in PbO-PVC nanocomposite polymer membranes

Different plants can be used to prepare nanoparticles. This is termed as green technology. It is one of the best ecofriendly and low-cost method for the preparation of nanoparticles which has no harmful effects. PbO nanoparticles were prepared by green method using leaf extract of Datura Sternum plants. The preparation of Lead oxide was confirmed by color change from colorless to yellowish brown. UV-Visible peak obtained at 250 nm and XRD study clarified the formation of PbO NPs. These PbO nanoparticles were then applied for the preparation of Nano Composite Polymer Membranes (nCPMs). PbO-PVC nCPMs were prepared based on polyvinyl chloride (PVC) polymer and PbO filler with the help of solution casting method, using cyclohexanone as a solvent. Different percentage (5-35%) of filler was used. The physiochemical parameters studied were viscosity, water uptake (WU), perpendicular swelling (DT) in deionized water, density, porosity (ε), morphology, ion adsorption capacity (IAC) and electrical conductivity (σ). The values of all these parameters except viscosity and conductivity were increased on increasing filler percentage. Viscosity of the nCPMs solution was decreased from 171 to 46.21. The conductivity of nCPMs was first increased upto 25% filler and then decreased. The deformation in PVC structure was increased on enhancing PbO amount. The values of Density, porosity, water uptake, DT and IAC were found in range 1.15-5.02, 0.50-0.87, 72.01-141.30, 0.012-0.11, and 3.13 × 10⁷-8.60 × 10⁷ respectively.

Optogenetic approaches for termination of ventricular tachyarrhythmias after myocardial infarction in rats in vivo

Cardiac optogenetics facilitates the painless manipulation of the heart with optical energy and was recently shown to terminate ventricular tachycardia (VT) in explanted mice heart. This study aimed to evaluate the optogenetic-based termination of induced VT under ischemia in an open-chest rat model and to develop an optimal, optical-manipulation procedure. VT was induced by burst stimulation after ligation of the left anterior descending coronary artery, and the termination effects of the optical manipulation, including electrical anti-tachycardia pacing (ATP) and spontaneous recovery, were tested. Among different multisegment optical modes, four repeated illuminations of 1000 ms in duration with 1-second interval at a 20-times intensity threshold on the right ventricle achieved the highest termination rate of 86.14% ± 4.145%, higher than that achieved by ATP and spontaneous termination. We demonstrated that optogenetic-based cardioversion is feasible and effective in vivo, with the underlying mechanism involving the light-triggered, ChR2-induced depolarization of the illuminated myocardium, in turn generating an excitation that disrupts the preexisting reentrant wave front.

Synthesis, crystal structure, Hirshfeld surface and interaction energies analysis of 5-methyl-1,3-bis(3-nitrobenzyl)pyrimidine-2,4(1H,3H)-dione

The title compound 5-methyl-1,3-bis(3-nitrobenzyl)pyrimidine-2,4(1H,3H)-dione was obtained by reaction of thymine with 3-nitrobenzylbromide in the presence of cesium carbonate. Characterization of the product was achieved by NMR spectroscopy and its stability was probed in basic condition using UV-Visible analysis. Furthermore, the molecular structure was confirmed by X-ray diffraction analysis. The compound crystallizes in orthorhombic Pna21 space group with unit cell parameters a = 14.9594 (15) Å, b = 25.711 (3) Å, c = 4.5004 (4) Å, V = 1731.0 (3) Å3 and Z = 4. The crystal packing of the title compound is stabilized by intermolecular hydrogen bond, π···π and C−H···π stacking interactions. The intermolecular interactions were furthermore analyzed through the mapping of different Hirshfeld surfaces. The two-dimensional fingerprint revealed that the most important contributions to these surfaces come from O···H (37.1%), H···H (24%) and H···C/C···H (22.6%) interactions. The interaction energies stabilizing the crystal packing were calculated and were presented graphically as framework energy diagrams. Finally, the energy-framework analysis reveals that π···π and C−H···π interactions energies are mainly dispersive and are the most important forces in the crystal.

Non-invasive red-light optogenetic control of Drosophila cardiac function

Drosophila is a powerful genetic model system for cardiovascular studies. Recently, optogenetic pacing tools have been developed to control Drosophila heart rhythm noninvasively with blue light, which has a limited penetration depth. Here we developed both a red-light sensitive opsin expressing Drosophila system and an integrated red-light stimulation and optical coherence microscopy (OCM) imaging system. We demonstrated noninvasive control of Drosophila cardiac rhythms using a single light source, including simulated tachycardia in ReaChR-expressing flies and bradycardia and cardiac arrest in halorhodopsin (NpHR)-expressing flies at multiple developmental stages. By using red excitation light, we were able to pace flies at higher efficiency and with lower power than with equivalent blue light excitation systems. The recovery dynamics after red-light stimulation of NpHR flies were observed and quantified. The combination of red-light stimulation, OCM imaging, and transgenic Drosophila systems provides a promising and easily manipulated research platform for noninvasive cardiac optogenetic studies.

Men et al. develop an optogenetic pacing tool to control Drosophila heart rhythm noninvasively with red light. Using optical coherence microscopy imaging, they demonstrate effective light-induced tachypacing, bradypacing, and restorable cardiac arrest in transgenic fly models. This study provides a user-friendly research platform for noninvasive cardiac optogenetic studies.

Expression of a stress-responsive gene cluster for mycosporine-2-glycine confers oxidative stress tolerance in Synechococcus elongatus PCC7942

Mycosporine-like amino acids (MAAs) are a class of well-documented UV-screening compounds produced by taxonomically diverse organisms. Extensive studies revealed that a rare MAA, mycosporine-2-glycine (M2G), possesses unique biological activities and functions. M2G is not only a potent antioxidant, but also suppresses protein glycation in vitro, and production of inflammatory mediators in RAW 264.7 macrophages. The present study evaluates vital functions of M2G in a heterologous expression system. The stress-sensitive fresh water cyanobacterium Synechococcus elongatus PCC7942, carrying a M2G biosynthetic gene cluster, was generated. The M2G-expressing cells were more tolerant to H2O2-induced oxidative stress than the wild type, with a half-maximal inhibitory concentration (IC50) value of 2.3 ± 0.06 mM. Transcriptional analysis revealed that all M2G biosynthetic genes were highly up-regulated under oxidative stress. Further, expression of vital genes in the cellular antioxidant defense system, including sodB, cat and tpxA were modulated and up-regulated. Elevated M2G was detected under oxidative stress as well as salt stress treatments. This study provides insight into the molecular and cellular effects of the M2G biosynthetic gene cluster, contributing to understanding of the mechanism behind physiological plasticity under this heterologous expression system.

Optimizing Dosing of Vagus Nerve Stimulation for Stroke Recovery

Vagus nerve stimulation (VNS) paired with rehabilitative training enhances recovery of function in models of stroke and is currently under investigation for use in chronic stroke patients. Dosing is critical in translation of pharmacological therapies, but electrical stimulation therapies often fail to comprehensively explore dosing parameters in preclinical studies. Varying VNS parameters has non-monotonic effects on plasticity in the central nervous system, which may directly impact efficacy for stroke. We sought to optimize stimulation intensity to maximize recovery of motor function in a model of ischemic stroke. The study design was preregistered prior to beginning data collection (DOI: https://doi.org/10.17605/OSF.IO/BMJEK ). After training on an automated assessment of forelimb function and receiving an ischemic lesion in motor cortex, rats were separated into groups that received rehabilitative training paired with VNS at distinct stimulation intensities (sham, 0.4 mA, 0.8 mA, or 1.6 mA). Moderate-intensity VNS at 0.8 mA enhanced recovery of function compared with all other groups. Neither 0.4 mA nor 1.6 mA VNS was sufficient to improve functional recovery compared with equivalent rehabilitation without VNS. These results demonstrate that moderate-intensity VNS delivered during rehabilitation improves recovery and defines an optimized intensity paradigm for clinical implementation of VNS therapy.