Metabolic engineering of Synechocystis sp. PCC 6803 for the improved production of phenylpropanoids.

BACKGROUND: Phenylpropanoids are a large group of plant secondary metabolites with various biological functions, derived from aromatic amino acids. Cyanobacteria are promising host organisms for sustainable production of plant phenylpropanoids. We have previously engineered Synechocystis sp. PCC 6803 to produce trans-cinnamic acid (tCA) and p-coumaric acid (pCou), the first intermediates of phenylpropanoid pathway, by overexpression of phenylalanine- and tyrosine ammonia lyases. In this study, we aimed to enhance the production of the target compounds tCA and pCou in Synechocystis. RESULTS: We eliminated the 4-hydroxyphenylpyruvate dioxygenase (HPPD) activity, which is a competing pathway consuming tyrosine and, possibly, phenylalanine for tocopherol synthesis. Moreover, several genes of the terminal steps of the shikimate pathway were overexpressed alone or in operons, such as aromatic transaminases, feedback insensitive cyclohexadienyl dehydrogenase (TyrC) from Zymomonas mobilis and the chorismate mutase (CM) domain of the fused chorismate mutase/prephenate dehydratase enzyme from Escherichia coli. The obtained engineered strains demonstrated nearly 1.5 times enhanced tCA and pCou production when HPPD was knocked out compared to the parental production strains, accumulating 138 ± 3.5 mg L-1 of tCA and 72.3 ± 10.3 mg L-1 of pCou after seven days of photoautotrophic growth. However, there was no further improvement when any of the pathway genes were overexpressed. Finally, we used previously obtained AtPRM8 and TsPRM8 Synechocystis strains with deregulated shikimate pathway as a background for the overexpression of synthetic constructs with ppd knockout. CONCLUSIONS: HPPD elimination enhances the tCA and pCou productivity to a similar extent. The use of PRM8 based strains as a background for overexpression of synthetic constructs, however, did not promote tCA and pCou titers, which indicates a tight regulation of the terminal steps of phenylalanine and tyrosine synthesis. This work contributes to establishing cyanobacteria as hosts for phenylpropanoid production.

Tailoring regulatory components for metabolic engineering in cyanobacteria.

The looming climate crisis has prompted an ever-growing interest in cyanobacteria due to their potential as sustainable production platforms for the synthesis of energy carriers and value-added chemicals from CO2 and sunlight. Nonetheless, cyanobacteria are yet to compete with heterotrophic systems in terms of space-time yields and consequently production costs. One major drawback leading to the low production performance observed in cyanobacteria is the limited ability to utilize the full capacity of the photosynthetic apparatus and its associated systems, i.e. CO2 fixation and the directly connected metabolism. In this review, novel insights into various levels of metabolic regulation of cyanobacteria are discussed, including the potential of targeting these regulatory mechanisms to create a chassis with a phenotype favorable for photoautotrophic production. Compared to conventional metabolic engineering approaches, minor perturbations of regulatory mechanisms can have wide-ranging effects.

Experiences of the use of portfolio in dental education - A qualitative meta-ethnographic literature review.

INTRODUCTION: Portfolio with a collection of evidence has become popular in higher education, including dental education. It is valuable to study the experiences of the use and implementation processes. Meta-ethnography can be a suitable method to analyse, synthesize and construct interpretations of qualitative research. Our aim was to explore experiences from the use of a portfolio/e-portfolio in dental education, from the students' and teachers' perspectives. MATERIALS AND METHODS: A systematic search in the databases PubMed, Scopus and ERC was performed, and the established seven steps of a meta-ethnographic review were used. 278 papers were initially identified, and seven were included in the final analysis. RESULTS: Two themes (Issues to Address and Consequences) and five subthemes (Purpose, Roles, Support and Structure, Challenges and Enablers, and Gains) were constructed. DISCUSSION: Our synthesis reflects various challenges, yet the learning gains are recognized and expressed to be important once the students and teachers have overcome early thresholds. Beyond the conclusions drawn in each paper, our synthesis provides new perspectives on the complexity of an implementation process and the balance of not seeing the woods for the trees being overwhelmed by technical and other practical aspects, reducing the opportunity for learning. CONCLUSION: The portfolio implementation in undergraduate dental education should address clarification to all stakeholders of the purpose and role, presenting a purposeful portfolio structure and timely support.

Laboratory evolution of Synechocystis sp. PCC 6803 for phenylpropanoid production.

Cyanobacteria are promising as a biotechnological platform for production of various industrially relevant compounds, including aromatic amino acids and their derivatives, phenylpropanoids. In this study, we have generated phenylalanine resistant mutant strains (PRMs) of the unicellular cyanobacterium Synechocystis sp. PCC 6803, by laboratory evolution under the selective pressure of phenylalanine, which inhibits the growth of wild type Synechocystis. The new strains of Synechocystis were tested for their ability to secrete phenylalanine in the growth medium during cultivation in shake flasks as well as in a high-density cultivation (HDC) system. All PRM strains secreted phenylalanine into the culture medium, with one of the mutants, PRM8, demonstrating the highest specific production of 24.9 ± 7 mg L-1·OD750-1 or 610 ± 196 mg L-1 phenylalanine after four days of growth in HDC. We further overexpressed phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) in the mutant strains in order to determine the potential of PRMs for production of trans-cinnamic acid (tCA) and para-coumaric acid (pCou), the first intermediates of the plant phenylpropanoid pathway. Productivities of these compounds were found to be lower in the PRMs compared to respective control strains, except for PRM8 under HDC conditions. The PRM8 background strain in combination with PAL or TAL expression demonstrated a specific production of 52.7 ± 15 mg L-1·OD750-1tCA and 47.1 ± 7 mg L-1·OD750-1pCou, respectively, with a volumetric titer reaching above 1 g L-1 for both products after four days of HDC cultivation. The genomes of PRMs were sequenced in order to identify which mutations caused the phenotype. Interestingly, all of the PRMs contained at least one mutation in their ccmA gene, which encodes DAHP synthase, the first enzyme of the pathway for aromatic amino acids biosynthesis. Altogether, we demonstrate that the combination of laboratory-evolved mutants and targeted metabolic engineering can be a powerful tool in cyanobacterial strain development.

Mapping competitive pathways to terpenoid biosynthesis in Synechocystis sp. PCC 6803 using an antisense RNA synthetic tool.

BACKGROUND: Synechocystis sp. PCC 6803 utilizes pyruvate and glyceraldehyde 3-phosphate via the methylerythritol 4-phosphate (MEP) pathway for the biosynthesis of terpenoids. Considering the deep connection of the MEP pathway to the central carbon metabolism, and the low carbon partitioning towards terpenoid biosynthesis, significant changes in the metabolic network are required to increase cyanobacterial production of terpenoids. RESULTS: We used the Hfq-MicC antisense RNA regulatory tool, under control of the nickel-inducible PnrsB promoter, to target 12 different genes involved in terpenoid biosynthesis, central carbon metabolism, amino acid biosynthesis and ATP production, and evaluated the changes in the performance of an isoprene-producing cyanobacterial strain. Six candidate targets showed a positive effect on isoprene production: three genes involved in terpenoid biosynthesis (crtE, chlP and thiG), two involved in amino acid biosynthesis (ilvG and ccmA) and one involved in sugar catabolism (gpi). The same strategy was applied to interfere with different parts of the terpenoid biosynthetic pathway in a bisabolene-producing strain. Increased bisabolene production was observed not only when interfering with chlorophyll a biosynthesis, but also with carotenogenesis. CONCLUSIONS: We demonstrated that the Hfq-MicC synthetic tool can be used to evaluate the effects of gene knockdown on heterologous terpenoid production, despite the need for further optimization of the technique. Possible targets for future engineering of Synechocystis aiming at improved terpenoid microbial production were identified.

Embedding environmental sustainability within oral health professional curricula-Recommendations for teaching and assessment of learning outcomes.

The FDI World Dental Federation suggests that "dentistry, as a profession, should integrate Sustainable Development Goals into daily practice and support a shift to a green economy in the pursuit of healthy lives and wellbeing for all, through all stages of life." This article reports on the recent activity of the Association for Dental Education in Europe Special Interest Group for Sustainability in Dentistry. Following on from the group's previous activities, which explored current educational practice, this work aimed to reach a pan-European consensus on a number of learning outcomes for environmental sustainability, in order to (i) support institutions in designing and delivering their curriculum, and (ii) to further harmonise the delivery of oral health professional education across Europe. This article presents specific learning outcomes relating to environmental sustainability and recommendations relating to curriculum development, including methods of teaching and assessment.

Expression of phenylalanine ammonia lyases in Synechocystis sp. PCC 6803 and subsequent improvements of sustainable production of phenylpropanoids.

BACKGROUND: Phenylpropanoids represent a diverse class of industrially important secondary metabolites, synthesized in plants from phenylalanine and tyrosine. Cyanobacteria have a great potential for sustainable production of phenylpropanoids directly from CO2, due to their photosynthetic lifestyle with a fast growth compared to plants and the ease of generating genetically engineered strains. This study focuses on photosynthetic production of the starting compounds of the phenylpropanoid pathway, trans-cinnamic acid and p-coumaric acid, in the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis). RESULTS: A selected set of phenylalanine ammonia lyase (PAL) enzymes from different organisms was overexpressed in Synechocystis, and the productivities of the resulting strains compared. To further improve the titer of target compounds, we evaluated the use of stronger expression cassettes for increasing PAL protein levels, as well as knock-out of the laccase gene slr1573, as this was previously reported to prevent degradation of the target compounds in the cell. Finally, to investigate the effect of growth conditions on the production of trans-cinnamic and p-coumaric acids from Synechocystis, cultivation conditions promoting rapid, high density growth were tested. Comparing the different PALs, the highest specific titer was achieved for the strain AtC, expressing PAL from Arabidopsis thaliana. A subsequent increase of protein level did not improve the productivity. Production of target compounds in strains where the slr1573 laccase had been knocked out was found to be lower compared to strains with wild type background, and the Δslr1573 strains exhibited a strong phenotype of slower growth rate and lower pigment content. Application of a high-density cultivation system for the growth of production strains allowed reaching the highest total titers of trans-cinnamic and p-coumaric acids reported so far, at around 0.8 and 0.4 g L-1, respectively, after 4 days. CONCLUSIONS: Production of trans-cinnamic acid, unlike that of p-coumaric acid, is not limited by the protein level of heterologously expressed PAL in Synechocystis. High density cultivation led to higher titres of both products, while knocking out slr1573 did not have a positive effect on production. This work contributes to capability of exploiting the primary metabolism of cyanobacteria for sustainable production of plant phenylpropanoids.

Production of succinate by engineered strains of Synechocystis PCC 6803 overexpressing phosphoenolpyruvate carboxylase and a glyoxylate shunt.

BACKGROUND: Cyanobacteria are promising hosts for the production of various industrially important compounds such as succinate. This study focuses on introduction of the glyoxylate shunt, which is naturally present in only a few cyanobacteria, into Synechocystis PCC 6803. In order to test its impact on cell metabolism, engineered strains were evaluated for succinate accumulation under conditions of light, darkness and anoxic darkness. Each condition was complemented by treatments with 2-thenoyltrifluoroacetone, an inhibitor of succinate dehydrogenase enzyme, and acetate, both in nitrogen replete and deplete medium. RESULTS: We were able to introduce genes encoding the glyoxylate shunt, aceA and aceB, encoding isocitrate lyase and malate synthase respectively, into a strain of Synechocystis PCC 6803 engineered to overexpress phosphoenolpyruvate carboxylase. Our results show that complete expression of the glyoxylate shunt results in higher extracellular succinate accumulation compared to the wild type control strain after incubation of cells in darkness and anoxic darkness in the presence of nitrate. Addition of the inhibitor 2-thenoyltrifluoroacetone increased succinate titers in all the conditions tested when nitrate was available. Addition of acetate in the presence of the inhibitor further increased the succinate accumulation, resulting in high levels when phosphoenolpyruvate carboxylase was overexpressed, compared to control strain. However, the highest succinate titer was obtained after dark incubation of an engineered strain with a partial glyoxylate shunt overexpressing isocitrate lyase in addition to phosphoenolpyruvate carboxylase, with only 2-thenoyltrifluoroacetone supplementation to the medium. CONCLUSIONS: Heterologous expression of the glyoxylate shunt with its central link to the tricarboxylic acid cycle (TCA) for acetate assimilation provides insight on the coordination of the carbon metabolism in the cell. Phosphoenolpyruvate carboxylase plays an important role in directing carbon flux towards the TCA cycle.

Photoautotrophic production of renewable ethylene by engineered cyanobacteria: Steering the cell metabolism towards biotechnological use.

Ethylene is a volatile hydrocarbon with a massive global market in the plastic industry. The ethylene now used for commercial applications is produced exclusively from nonrenewable petroleum sources, while competitive biotechnological production systems do not yet exist. This review focuses on the currently developed photoautotrophic bioproduction strategies that enable direct solar-driven conversion of CO2 into ethylene, based on the use of genetically engineered photosynthetic cyanobacteria expressing heterologous ethylene forming enzyme (EFE) from Pseudomonas syringae. The emphasis is on the different engineering strategies to express EFE and to direct the cellular carbon flux towards the primary metabolite 2-oxoglutarate, highlighting associated metabolic constraints, and technical considerations on cultivation strategies and conditional parameters. While the research field has progressed towards more robust strains with better production profiles, and deeper understanding of the associated metabolic limitations, it is clear that there is room for significant improvement to reach industrial relevance. At the same time, existing information and the development of synthetic biology tools for engineering cyanobacteria open new possibilities for improving the prospects for the sustainable production of renewable ethylene.

Doing synthetic biology with photosynthetic microorganisms.

The use of photosynthetic microbes as synthetic biology hosts for the sustainable production of commodity chemicals and even fuels has received increasing attention over the last decade. The number of studies published, tools implemented, and resources made available for microalgae have increased beyond expectations during the last few years. However, the tools available for genetic engineering in these organisms still lag those available for the more commonly used heterotrophic host organisms. In this mini-review, we provide an overview of the photosynthetic microbes most commonly used in synthetic biology studies, namely cyanobacteria, chlorophytes, eustigmatophytes and diatoms. We provide basic information on the techniques and tools available for each model group of organisms, we outline the state-of-the-art, and we list the synthetic biology tools that have been successfully used. We specifically focus on the latest CRISPR developments, as we believe that precision editing and advanced genetic engineering tools will be pivotal to the advancement of the field. Finally, we discuss the relative strengths and weaknesses of each group of organisms and examine the challenges that need to be overcome to achieve their synthetic biology potential.

An upgrade of the Malmö model by implementing case-based teaching and learning, in an undergraduate dental education.

BACKGROUND: At our dental education, the examination failure rate amongst students has increased, resulting in subsequent involuntary dropouts. One of the main problems seems to be that the students struggle with taking the necessary responsibility for their learning, as required by the problem-based learning (PBL) methodology. AIM: To describe the background to, and the transition process from, pure PBL to case-based teaching and learning (CBT) with flipped classroom seminars at the dental programme at [anonymised for peer review]. METHODS: In this position paper, we describe our observed problems with the PBL methodology, as implemented at this faculty, and the potential benefits of a change towards CBT. The current implementation of CBT is presented, along with educational research supporting the choice of activities. RESULTS: Tentative findings are that the flipped classroom seminars and the clearer instructions appear to be successful with higher levels of activity, engagement and attendance amongst the students, and the students have evaluated the seminars as very good learning activities. CONCLUSION: Tentative findings suggest that the current implementation of CBT may be a fruitful way of teaching in dental education today. Most of the teaching staff have been reawakened to teaching, and as a result, the content of the courses are being reviewed and improved. The students appreciate that what is expected of them has been made clearer and that there is a variety of learning activities.

Engineered cyanobacteria with enhanced growth show increased ethanol production and higher biofuel to biomass ratio.

The Calvin-Benson-Bassham (CBB) cycle is the main pathway to fix atmospheric CO2 and store energy in carbon bonds, forming the precursors of most primary and secondary metabolites necessary for life. Speeding up the CBB cycle theoretically has positive effects on the subsequent growth and/or the end metabolite(s) production. Four CBB cycle enzymes, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), fructose-1,6/sedoheptulose-1,7-bisphosphatase (FBP/SBPase), transketolase (TK) and aldolase (FBA) were selected to be co-overexpressed with the ethanol synthesis enzymes pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) in the cyanobacterium Synechocystis PCC 6803. An inducible promoter, PnrsB, was used to drive PDC and ADH expression. When PnrsB was induced and cells were cultivated at 65 µmol photons m-2 s-1, the RuBisCO-, FBP/SBPase-, TK-, and FBA-expressing strains produced 55%, 67%, 37% and 69% more ethanol and 7.7%, 15.1%, 8.8% and 10.1% more total biomass (the sum of dry cell weight and ethanol), respectively, compared to the strain only expressing the ethanol biosynthesis pathway. The ethanol to total biomass ratio was also increased in CBB cycle enzymes overexpressing strains. This study experimentally demonstrates that using the cells with enhanced carbon fixation, when the product synthesis pathway is not the main bottleneck, can significantly increase the generation of a product (exemplified with ethanol), which acts as a carbon sink.

Systematic overexpression study to find target enzymes enhancing production of terpenes in Synechocystis PCC 6803, using isoprene as a model compound.

Of the two natural metabolic pathways for making terpenoids, biotechnological utilization of the mevalonate (MVA) pathway has enabled commercial production of valuable compounds, while the more recently discovered but stoichiometrically more efficient methylerythritol phosphate (MEP) pathway is underdeveloped. We conducted a study on the overexpression of each enzyme in the MEP pathway in the unicellular cyanobacterium Synechocystis sp. PCC 6803, to identify potential targets for increasing flux towards terpenoid production, using isoprene as a reporter molecule. Results showed that the enzymes Ipi, Dxs and IspD had the biggest impact on isoprene production. By combining and creating operons out of those genes, isoprene production was increased 2-fold compared to the base strain. A genome-scale model was used to identify targets upstream of the MEP pathway that could redirect flux towards terpenoids. A total of ten reactions from the Calvin-Benson-Bassham cycle, lower glycolysis and co-factor synthesis pathways were probed for their effect on isoprene synthesis by co-expressing them with the MEP enzymes, resulting in a 60% increase in production from the best strain. Lastly, we studied two isoprene synthases with the highest reported catalytic rates. Only by expressing them together with Dxs and Ipi could we get stable strains that produced 2.8 mg/g isoprene per dry cell weight, a 40-fold improvement compared to the initial strain.

Sll1783, a monooxygenase associated with polysaccharide processing in the unicellular cyanobacterium Synechocystis PCC 6803.

Cyanobacteria play a pivotal role as the primary producer in many aquatic ecosystems. The knowledge on the interacting processes of cyanobacteria with its environment - abiotic and biotic factors - is still very limited. Many potential exocytoplasmic proteins in the model unicellular cyanobacterium Synechocystis PCC 6803 have unknown functions and their study is essential to improve our understanding of this photosynthetic organism and its potential for biotechnology use. Here we characterize a deletion mutant of Synechocystis PCC 6803, Δsll1783, a strain that showed a remarkably high light resistance which is related with its lower thylakoid membrane formation. Our results suggests Sll1783 to be involved in a mechanism of polysaccharide degradation and uptake and we hypothesize it might function as a sensor for cell density in cyanobacterial cultures.

Higher expression of WNT5A protein in oral squamous cell carcinoma compared with dysplasia and oral mucosa with a normal appearance.

WNT5A is a secreted signaling protein that promotes migration and invasion of oral squamous cell carcinoma (OSCC) cells through activation of non-canonical WNT signaling. Here, we examined expression of WNT5A, ß-catenin, and E-cadherin by immunohistochemistry in 21 human diagnostic incision biopsies that each had regions of oral mucosa with a normal appearance adjacent to the affected tissue, dysplasia, and OSCC. We also investigated the effect of recombinant WNT5A (rWNT5A) on expression of the cell-adhesion proteins E-cadherin and ß-catenin by western blot analysis. No expression of WNT5A protein was present in oral mucosa with a normal appearance or in mild grade dysplasia. However, expression of WNT5A increased along with increasing grade of dysplasia, and the highest expression was detected in OSCCs. Expression of membranous ß-catenin and of E-cadherin was lower, whereas expression of cytoplasmic ß-catenin was higher, in OSCCs than in non-cancerous regions. However, there was no correlation between expression of WNT5A and expression of either ß-catenin or E-cadherin. Furthermore, treatment of OSCC cells with rWNT5A had no effect on the expression of ß-catenin or E-cadherin. Taken together with previous results, we conclude that WNT5A influences the progression of OSCC without affecting the canonical WNT/ß-catenin pathway and without down-regulating E-cadherin. WNT5A may have potential as a biological marker for malignant transformation of dysplasia to OSCC.

Migration and invasion of oral squamous carcinoma cells is promoted by WNT5A, a regulator of cancer progression.

BACKGROUND: Oral squamous cell carcinoma (OSCC) constitutes 90% of all cancers in the oral cavity, and the prognosis for patients diagnosed with OSCC is still poor. The identification of novel therapeutic targets and prognostic markers for OSCC is therefore essential. Previous studies of OSCC revealed an increased expression of WNT5A in the tumor tissue. However, no functional studies of WNT5A-induced effects in OSCC have been performed. METHODS: Two different OSCC cell lines were used for analysis of WNT5A expression by Western blot, whereas WNT5A-induced responses were analyzed by measuring calcium (Ca²âº) signaling, PKC activation, migration and invasion. RESULTS: Despite the lack of WNT5A expression, both cell lines responded to recombinant WNT5A (rWNT5A) with activation of the non-canonical WNT/Ca²âº /PKC pathway. This effect was ascertained to be mediated by WNT5A by use of the WNT5A antagonist, Box5. To investigate how WNT5A affects tumor progression, rWNT5A-induced alterations in BrdU absorbance (reflecting the number of tumor cells) were analyzed. rWNT5A had no effect on BrdU absorbance but instead promoted tumor cell migration and invasion. These results were confirmed by the use of the WNT5A-mimicking peptide Foxy5, while the rWNT5A-induced migration was blocked by secreted Frizzled-related protein 1 (SFRP1), protein kinase C inhibitors or the intracellular Ca²âº chelator, MAPT. CONCLUSIONS: These novel data clearly show that WNT5A activates the non-canonical WNT/Ca²âº /PKC pathway and increases migration and invasion of OSCC cells. This may indicate how an increased WNT5A expression in the tumor tissue is likely to promote progression of OSCC.

Neuron navigator 3 alterations in nervous system tumors associate with tumor malignancy grade and prognosis.

Copy number changes or reduced expression of the Neuron navigator 3 (NAV3) gene occurs in neuroblastomas and malignancies of epithelial or lymphoid origin. To elucidate whether NAV3 has a role in the tumorigenesis of nervous system tumors in general, we studied central and peripheral nervous system tumors for NAV3 copy number changes. In search for common tumorigenic denominators, we analyzed 113 central and peripheral nervous system tumors, including glial tumors (grades I-IV gliomas), medulloblastomas, and neuroblastomas. NAV3 copy number changes were studied by fluorescence in situ hybridization and correlated to survival analyses. To identify target genes of NAV3 deletion, NAV3 was silenced by siRNA in glioblastoma cell lines and gene expression profiles were analyzed by Agilent 4×44k dual-color microarrays. Selected upregulations were confirmed by immunohistochemistry and quantitative polymerase chain reaction. We found NAV3 amplifications to dominate in neuronally differentiated tumors, whereas glial tumors showed almost equal proportions of NAV3 deletion and amplification. However, Grade IV gliomas had more frequent NAV3 deletions than grades I-III gliomas. Silencing of NAV3 in glioma cell lines led to the upregulation of receptor genes associated with gonadotropin-releasing hormone and Jak-Stat signaling pathways. Kaplan-Meier analysis of the entire clinical tumor material showed association between NAV3 amplifications and favorable prognosis, as well as NAV3 deletions and unfavorable prognosis. With Cox regression model, a hazard ratio of 0.51 was observed for NAV3 amplifications and 1.36 for NAV3 deletions. We conclude that NAV3 may be a potential new prognostic biomarker and a potential therapeutic target.

CORACLE (COVID-19 liteRAture CompiLEr): A platform for efficient tracking and extraction of SARS-CoV-2 and COVID-19 literature, with examples from post-COVID with respiratory involvement.

Background: During the COVID-19 pandemic a need to process large volumes of publications emerged. As the pandemic is winding down, the clinicians encountered a novel syndrome - Post-acute Sequelae of COVID-19 (PASC) - that affects over 10 % of those who contract SARS-CoV-2 and presents a significant challenge in the medical field. The continuous influx of publications underscores a need for efficient tools for navigating the literature. Objectives: We aimed to develop an application which will allow monitoring and categorizing COVID-19-related literature through building publication networks and medical subject headings (MeSH) maps to identify key publications and networks. Methods: We introduce CORACLE (COVID-19 liteRAture CompiLEr), an innovative web application designed to analyse COVID-19-related scientific articles and to identify research trends. CORACLE features three primary interfaces: The "Search" interface, which displays research trends and citation links; the "Citation Map" interface, allowing users to create tailored citation networks from PubMed Identifiers (PMIDs) to uncover common references among selected articles; and the "MeSH" interface, highlighting current MeSH trends and their associations. Results: CORACLE leverages PubMed data to categorize literature on COVID-19 and PASC, aiding in the identification of relevant research publication hubs. Using lung function in PASC patients as a search example, we demonstrate how to identify and visualize the interactions between the relevant publications. Conclusion: CORACLE is an effective tool for the extraction and analysis of literature. Its functionalities, including the MeSH trends and customizable citation mapping, facilitate the discovery of emerging trends in COVID-19 and PASC research.

Introduction to Cyanobacteria.

Cyanobacteria are highly interesting microbes with the capacity for oxygenic photosynthesis. They fulfill an important purpose in nature but are also potent biocatalysts. This chapter gives a brief overview of this diverse phylum and shortly addresses the functions these organisms have in the natural ecosystems. Further, it introduces the main topics covered in this volume, which is dealing with the development and application of cyanobacteria as solar cell factories for the production of chemicals including potential fuels. We discuss cyanobacteria as industrial workhorses, present established chassis strains, and give an overview of the current target products. Genetic engineering strategies aiming at the photosynthetic efficiency as well as approaches to optimize carbon fluxes are summarized. Finally, main cultivation strategies are sketched.

Characterizing isoprene production in cyanobacteria - Insights into the effects of light, temperature, and isoprene on Synechocystis sp. PCC 6803.

Engineering cyanobacteria for the production of isoprene and other terpenoids has gained increasing attention in the field of biotechnology. Several studies have addressed optimization of isoprene synthesis in cyanobacteria via enzyme and pathway engineering. However, only little attention has been paid to the optimization of cultivation conditions. In this study, an isoprene-producing strain of Synechocystis sp. PCC 6803 and two control strains were grown under a variety of cultivation conditions. Isoprene production, as quantified by modified membrane inlet mass spectrometer (MIMS) and interpreted using Flux Balance Analysis (FBA), increased under violet light and at elevated temperature. Increase of thermotolerance in the isoprene producer was attributed to the physical presence of isoprene, similar to plants. The results demonstrate a beneficial effect of isoprene on cell survival at higher temperatures. This increased thermotolerance opens new possibilities for sustainable bio-production of isoprene and other products.