Cyanobacteria are prokaryotic organisms that capture energy from sunlight using oxygenic photosynthesis and transform CO
into products of interest such as fatty acids.
PCC 7942 is a model ...cyanobacterium efficiently engineered to accumulate high levels of omega-3 fatty acids. However, its exploitation as a microbial cell factory requires a better knowledge of its metabolism, which can be approached by using systems biology tools. To fulfill this objective, we worked out an updated, more comprehensive, and functional genome-scale model of this freshwater cyanobacterium, which was termed
MS837. The model includes 837 genes, 887 reactions, and 801 metabolites. When compared with previous models of
PCC 7942,
MS837 is more complete in key physiological and biotechnologically relevant metabolic hubs, such as fatty acid biosynthesis, oxidative phosphorylation, photosynthesis, and transport, among others.
MS837 shows high accuracy when predicting growth performance and gene essentiality. The validated model was further used as a test-bed for the assessment of suitable metabolic engineering strategies, yielding superior production of non-native omega-3 fatty acids such as α-linolenic acid (ALA). As previously reported, the computational analysis demonstrated that
overexpression is a feasible metabolic target to increase ALA production, whereas deletion and overexpression of
cannot be used for this purpose. Flux scanning based on enforced objective flux, a strain-design algorithm, allowed us to identify not only previously known gene overexpression targets that improve fatty acid synthesis, such as Acetyl-CoA carboxylase and β-ketoacyl-ACP synthase I, but also novel potential targets that might lead to higher ALA yields. Systematic sampling of the metabolic space contained in
MS837 identified a set of ten additional knockout metabolic targets that resulted in higher ALA productions.
simulations under photomixotrophic conditions with acetate or glucose as a carbon source boosted ALA production levels, indicating that photomixotrophic nutritional regimens could be potentially exploited
to improve fatty acid production in cyanobacteria. Overall, we show that
MS837 is a powerful computational platform that proposes new metabolic engineering strategies to produce biotechnologically relevant compounds, using
PCC 7942 as non-conventional microbial cell factory.
Bacterial polyhydroxyalkanoates (PHAs) have emerged as promising eco-friendly alternatives to petroleum-based plastics since they are synthesized from renewable resources and offer exceptional ...properties. However, their production is limited to the stationary growth phase under nutrient-limited conditions, requiring customized strategies and costly two-phase bioprocesses. In this study, we tackle these challenges by employing a model-driven approach to reroute carbon flux and remove regulatory constraints using synthetic biology. We construct a collection of Pseudomonas putida-overproducing strains at the expense of plastics and lignin-related compounds using growth-coupling approaches. PHA production was successfully achieved during growth phase, resulting in the production of up to 46% PHA/cell dry weight while maintaining a balanced carbon-to-nitrogen ratio. Our strains are additionally validated under an upcycling scenario using enzymatically hydrolyzed polyethylene terephthalate as a feedstock. These findings have the potential to revolutionize PHA production and address the global plastic crisis by overcoming the complexities of traditional PHA production bioprocesses.
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•Model-driven carbon flux rerouting enhances PHA production from complex compounds•Removal of regulatory constraints overcomes nutrient limitation for PHA production•Up to 46% of PHA/CDW was achieved under a balanced C/N ratio
Manoli et al. present a library of model-driven optimized P. putida strains able to upcycle recalcitrant polymers toward high-value-added products, polyhydroxyalkanoates. Through strategic metabolic flux rerouting and removal of intrinsic regulatory constraints, high PHA yields were successfully achieved by effectively decoupling production from nutrient limitations.
Endothelial dysfunction is crucial in endotoxaemia‐derived sepsis syndrome pathogenesis. It is well accepted that lipopolysaccharide (LPS) induces endothelial dysfunction through immune system ...activation. However, LPS can also directly generate actions in endothelial cells (ECs) in the absence of participation by immune cells. Although interactions between LPS and ECs evoke endothelial death, a significant portion of ECs are resistant to LPS challenge. However, the mechanism that confers endothelial resistance to LPS is not known. LPS‐resistant ECs exhibit a fibroblast‐like morphology, suggesting that these ECs enter a fibrotic programme in response to LPS. Thus, our aim was to investigate whether LPS is able to induce endothelial fibrosis in the absence of immune cells and explore the underlying mechanism. Using primary cultures of ECs and culturing intact blood vessels, we demonstrated that LPS is a crucial factor to induce endothelial fibrosis. We demonstrated that LPS was able and sufficient to promote endothelial fibrosis, in the absence of immune cells through an activin receptor–like kinase 5 (ALK5) activity–dependent mechanism. LPS‐challenged ECs showed an up‐regulation of both fibroblast‐specific protein expression and extracellular matrix proteins secretion, as well as a down‐regulation of endothelial markers. These results demonstrate that LPS is a crucial factor in inducing endothelial fibrosis in the absence of immune cells through an ALK5‐dependent mechanism. It is noteworthy that LPS‐induced endothelial fibrosis perpetuates endothelial dysfunction as a maladaptive process rather than a survival mechanism for protection against LPS. These findings are useful in improving current treatment against endotoxaemia‐derived sepsis syndrome and other inflammatory diseases.
Polycomb Repressive Complex 2 (PRC2) mediates transcriptional silencing by catalyzing histone H3 lysine 27 trimethylation (H3K27me3), but its role in the maturation of postmitotic mammalian neurons ...remains largely unknown. We report that the PRC2 paralogs Ezh1 and Ezh2 are differentially expressed during hippocampal development. We show that depletion of Ezh2 leads to increased expression of PSD-95, a critical plasticity gene, and that reduced PSD-95 gene transcription is correlated with enrichment of Ezh2 at the PSD-95 gene promoter; however, the H3K27me3 epigenetic mark is not present at the PSD-95 gene promoter, likely due to the antagonizing effects of the H3S28P and H3K27Ac marks and the activity of the H3K27 demethylases JMJD3 and UTX. In contrast, increased PSD-95 gene transcription is accompanied by the presence of Ezh1 and elongation-engaged RNA Polymerase II complexes at the PSD-95 gene promoter, while knock-down of Ezh1 reduces PSD-95 transcription. These results indicate that Ezh1 and Ezh2 have antagonistic roles in regulating PSD-95 transcription.
Endothelial dysfunction is decisive in the progression of cardiovascular diseases. Lipopolysaccharide (LPS)-induced reactive oxygen species (ROS)-mediated endothelial cell death is a main feature ...observed in inflammation secondary to endotoxaemia, emerging as a leading cause of death among critically ill patients in intensive care units. However, the molecular mechanism underlying LPS-induced endothelial cell death is not well understood. Transient receptor protein melastatin 4 (TRPM4) is an ion channel associated with cell death that is expressed in endothelium and modulated by ROS. Here, we investigate the role of TRPM4 in LPS-induced endothelial cell death, testing whether suppression of the expression of TRPM4 confers endothelial cell resistance to LPS challenge.
Using primary cultures of human umbilical vein endothelial cells (HUVEC), we demonstrate that TRPM4 is critically involved in LPS-induced endothelial cell death. HUVEC exposed to LPS results in Na(+)-dependent cell death. Pharmacological inhibition of TRPM4 with 9-phenanthrol or glibenclamide protects endothelium against LPS exposure for 48 h. Furthermore, TRPM4-like currents increase in cells pre-treated with LPS and inhibited with glibenclamide. Of note, suppression of TRPM4 expression by siRNA or suppression of its activity in a dominant negative mutant is effective in decreasing LPS-induced endothelial cell death when cells are exposed to LPS for 24-30 h.
TRPM4 is critically involved in LPS-induced endothelial cell death. These results demonstrate that either pharmacological inhibition of TRPM4, suppression of TRPM4 expression, or inhibition of TRPM4 activity are able to protect endothelium against LPS injury. These results are useful in sepsis drug design and development of new strategies for sepsis therapy.
To assess the mechanisms involved in lipopolysaccharide (LPS)-induced neuronal cell death, we examined the cellular consequences of LPS exposure in differentiated PC12 neurons and primary hippocampal ...neurons.
Our data show that LPS is able to induce PC12 neuronal cell death without the participation of glial cells. Neuronal cell death was mediated by an increase in cellular reactive oxygen species (ROS) levels. Considering the prevalent role of specific ion channels in mediating the deleterious effect of ROS, we assessed their contribution to this process. Neurons exposed to LPS showed a significant intracellular Ca(2+) overload, and nonselective cationic channel blockers inhibited LPS-induced neuronal death. In particular, we observed that both LPS and hydrogen peroxide exposure strongly increased the expression of the transient receptor protein melastatin 7 (TRPM7), which is an ion channel directly implicated in neuronal cell death. Further, both LPS-induced TRPM7 overexpression and LPS-induced neuronal cell death were decreased with dithiothreitol, dipheniliodonium, and apocynin. Finally, knockdown of TRPM7 expression using small interference RNA technology protected primary hippocampal neurons and differentiated PC12 neurons from the LPS challenge.
This is the first report showing that TRPM7 is a key protein involved in neuronal death after LPS challenge.
We conclude that LPS promotes an abnormal ROS-dependent TRPM7 overexpression, which plays a crucial role in pathologic events, thus leading to neuronal dysfunction and death.
Background: Coronary arteries originate from the first portion of the aorta, emerging from the right and left aortic sinuses. They traverse through the subepicardium and coronary sulcus to supply the ...myocardium during diastolic function. The objective of this review was to understand how the hypoplasia and agenesis of the coronary arteries are associated with cardiac pathologies. Methods: The databases Medline, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS were researched until January 2024. An assurance tool for anatomical studies (AQUA) was used to evaluate methodological quality. The pooled prevalence was estimated using a random effects model. Results: A total of three studies met the established selection criteria for inclusion in this meta-analysis. The prevalence of coronary artery variants was 3% (CI = 2% to 8%), with a heterogeneity of 77%. The other studies were analyzed descriptively, along with their respective clinical considerations in the presence of the variant. Conclusions: Hypoplasia and the congenital absence of the coronary arteries are often incidental findings and understanding these variants is crucial to prevent misdiagnosis. Additionally, it is essential to exercise caution when considering surgical management for hearts with these variants.
Introduction: Psychological research can be conducted by researchers and by undergraduate or postgraduate students. At the undergraduate level, psychological research is especially challenging ...because of the limited ability of students to develop coherent and logical research problems and methodological approaches. Objective: This study aimed to identify the main research trends in undergraduate psychological theses at Peruvian universities. Quantitative and qualitative research design trends were identified as specific objectives. Methods: A descriptive and retrospective systematic review of psychological research thesis of Peruvian undergraduate students was conducted, starting the data extraction process starting with RENATI database for an initial screening phase. The data analysis was conducted in two phases. Results: The data were organized according to the following categories: sex of the authors, universities (1–5) according to their ranking, year of publication of the thesis, number of authors, designs, type of methodology, and topic of publication. Descriptive statistics were calculated on the basis of these categories. In the next phase, lexicometric and statistical textual analyses were used to identify research trends. Discussion: The main results showed that different topics were predominantly framed within the clinical and health psychology line of research, mainly those related to coping styles, psychological stress, and well-being.
Objective: This systematic review analyzes the anatomical variants in the pancreas and its ductal system to report on their association with pancreatic pathologies. Methods: We conducted a search of ...the MEDLINE, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS databases from their inception to July 2023. The methodological quality was assessed with the Anatomical Quality Assessment (AQUA) tool. Finally, the pooled prevalence was estimated using a random effects model. Results: 55 studies were found that met the eligibility criteria. The overall prevalence of pancreas divisum (PD) was 18% (95% CI = 15–21%). The prevalence of PD associated with pancreatitis was 30% (95% CI = 1–61%). Conclusions: An anatomical variant of the pancreas such as PD may be the cause of bile duct obstruction, resulting in various clinical complications, such as pancreatitis. Hence, knowing this variant is extremely important for surgeons, especially for those who treat the gastroduodenal region.
The recurrent laryngeal nerve (RLN) is the structure responsible for sensory and motor innervation of the larynx, and it has been shown that its lesion due to a lack of surgical rigor led to ...alterations such as respiratory obstruction due to vocal cords paralysis and permanent phonation impairment. The objectives of this review were to know the variants of the RLN and its clinical relevance in the neck region.
This review considered specific scientific articles that were written in Spanish or English and published between 1960 and 2022. A systematic search was carried out in the electronic databases MEDLINE, WOS, CINAHL, SCOPUS, SCIELO, and Latin American and Caribbean Center for Information on Health Sciences to compile the available literature on the subject to be treated and was enrolled in PROSPERO. The included articles were studies that had a sample of RLN dissections or imaging, intervention group to look for RLN variants, or the comparison of the non-recurrent laryngeal nerve (NRLN) variants, and finally, its clinical correlations. Review articles and letters to the editor were excluded. All included articles were evaluated through quality assessment and risk of bias analysis using the methodological quality assurance tool for anatomical studies (AQUA). The extracted data in the meta-analysis were interpreted to calculate the prevalence of the RLN variants and their comparison and the relationship between the RLN and NRLN. The heterogeneity degree between included studies was assessed.
The included studies that showed variants of the RLN included in this review were 41, a total of 29,218. For the statistical analysis of the prevalence of the RLN variant, a forest plot was performed with 15 studies that met the condition of having a prevalence of less than 100%. As a result, the prevalence was shown to be 12% (95% CI, SD 0.11 to 0.14). Limitations that were present in this review were the publication bias of the included studies, the probability of not having carried out the most sensitive and specific search, and finally, the authors' personal inclinations in selecting the articles.
This meta-analysis can be considered based on an update of the prevalence of RLN variants, in addition to considering that the results show some clinical correlations such as intra-surgical complications and with some pathologies and aspects function of the vocal cords, which could be a guideline in management prior to surgery or of interest for the diagnostic.
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