Emerging nitrogen-fixing cyanobacteria for sustainable cotton cultivation.

Amid growing environmental concerns and the imperative for sustainable agricultural practices, this study examines the potential of nitrogen-fixing cyanobacteria as biofertilizers, particularly in cotton cultivation. The reliance on synthetic nitrogen fertilizers (SNFs), prevalent in modern agriculture, poses significant environmental challenges, including greenhouse gas emissions and water system contamination. This research aims to shift this paradigm by exploring the capacity of cyanobacteria as a natural and sustainable alternative. Utilizing advanced metabarcoding methods to analyze the 16S rRNA gene, we conducted a comprehensive assessment of soil bacterial communities within cotton fields. This study focused on evaluating the diversity, structure, taxonomic composition, and potential functional characteristics of these communities. Emphasis was placed on the isolation of native N2-fixing cyanobacteria strains rom cotton soils, and their subsequent effects on cotton growth. Results from our study demonstrate significant plant growth-promoting (PGP) activities, measured as N2 fixation, production of Phytohormones, Fe solubilization and biofertilization potential of five isolated cyanobacterial strains, underscoring their efficacy in cotton. These findings suggest a viable pathway for replacing chemical-synthetic nitrogen fertilizers with natural, organic alternatives. The reintegration of these beneficial species into agricultural ecosystems can enhance crop growth while fostering a balanced microbial environment, thus contributing to the broader goals of global sustainable agriculture.

CyanoCyc cyanobacterial web portal.

CyanoCyc is a web portal that integrates an exceptionally rich database collection of information about cyanobacterial genomes with an extensive suite of bioinformatics tools. It was developed to address the needs of the cyanobacterial research and biotechnology communities. The 277 annotated cyanobacterial genomes currently in CyanoCyc are supplemented with computational inferences including predicted metabolic pathways, operons, protein complexes, and orthologs; and with data imported from external databases, such as protein features and Gene Ontology (GO) terms imported from UniProt. Five of the genome databases have undergone manual curation with input from more than a dozen cyanobacteria experts to correct errors and integrate information from more than 1,765 published articles. CyanoCyc has bioinformatics tools that encompass genome, metabolic pathway and regulatory informatics; omics data analysis; and comparative analyses, including visualizations of multiple genomes aligned at orthologous genes, and comparisons of metabolic networks for multiple organisms. CyanoCyc is a high-quality, reliable knowledgebase that accelerates scientists' work by enabling users to quickly find accurate information using its powerful set of search tools, to understand gene function through expert mini-reviews with citations, to acquire information quickly using its interactive visualization tools, and to inform better decision-making for fundamental and applied research.

Phylogenetic and functional analysis of cyanobacterial Cytochrome c6-like proteins.

All known photosynthetic cyanobacteria carry a cytochrome c 6 protein that acts transferring electrons from cytochrome b 6 f complex to photosystem I, in photosynthesis, or cytochrome c oxidase, in respiration. In most of the cyanobacteria, at least one homologue to cytochrome c 6 is found, the so-called cytochrome c 6B or cytochrome c 6C. However, the function of these cytochrome c 6-like proteins is still unknown. Recently, it has been proposed a common origin of these proteins as well as the reclassification of the cytochrome c 6C group as c 6B, renaming the new joint group as cytochrome c 6BC. Another homologue to cytochrome c 6 has not been classified yet, the formerly called cytochrome c 6-3, which is present in the heterocyst-forming filamentous cyanobacteria Nostoc sp. PCC 7119. In this work, we propose the inclusion of this group as an independent group in the genealogy of cytochrome c 6-like proteins with significant differences from cytochrome c 6 and cytochrome c 6BC, with the proposed name cytochrome c 6D. To support this proposal, new data about phylogeny, genome localisation and functional properties of cytochrome c 6-like proteins is provided. Also, we have analysed the interaction of cytochrome c 6-like proteins with cytochrome f by isothermal titration calorimetry and by molecular docking, concluding that c 6-like proteins could interact with cytochrome b 6 f complex in a similar fashion as cytochrome c 6. Finally, we have analysed the reactivity of cytochrome c 6-like proteins with membranes enriched in terminal oxidases of cyanobacteria by oxygen uptake experiments, concluding that cytochrome c 6D is able to react with the specific copper-oxidase of the heterocysts, the cytochrome c oxidase 2.

Directing cyanobacterial photosynthesis in a cytochrome c oxidase mutant using a heterologous electron sink.

Photosynthesis holds the promise of sustainable generation of useful products using light energy. Key to realizing this potential is the ability to rationally design photosynthesis to redirect energy and reductant derived from photons to desired products. Cytochrome P450s (P450s), which catalyze a broad array of reactions, have been engineered into a variety of photosynthetic organisms, where their activity has been shown to be photosynthesis-dependent, thus acting as heterologous sinks of electrons derived from photosynthesis. Furthermore, the addition of P450s can increase the photosynthetic capacity of the host organism. In this study, we developed this technology further using a P450 (CYP1A1) expressed in the cyanobacterium Synechococcus sp. PCC 7002. We show that rationally engineering photosynthesis by the removal of a competing electron sink, the respiratory terminal oxidase cytochrome c oxidase, increased the activity of CYP1A1. We provide evidence that this enhanced CYP1A1 activity was facilitated via an increase in the flux of electrons through Photosystem I. We also conducted a transcriptomic analysis on the designed strains to gain a more holistic understanding of how the cell responds to rational engineering. We describe a complex response including changes in expression of genes involved in photosynthesis and electron transfer linked to respiration. Specifically, the expression of CYP1A1 resulted in the reduction in expression of other natural electron dissipation pathways. This study emphasizes the potential for engineering photosynthetic organisms in biotechnology but also highlights the need to consider the broader impacts on cellular metabolism of any rationally induced changes.

Introduction of the Carotenoid Biosynthesis α-Branch Into Synechocystis sp. PCC 6803 for Lutein Production.

Lutein, made by the α-branch of the methyl-erythritol phosphate (MEP) pathway, is one of the most abundant xanthophylls in plants. It is involved in the structural stabilization of light-harvesting complexes, transfer of excitation energy to chlorophylls and photoprotection. In contrast, lutein and the α-branch of the MEP pathway are not present in cyanobacteria. In this study, we genetically engineered the cyanobacterium Synechocystis for the missing MEP α-branch resulting in lutein accumulation. A cassette comprising four Arabidopsis thaliana genes coding for two lycopene cyclases (AtLCYe and AtLCYb) and two hydroxylases (AtCYP97A and AtCYP97C) was introduced into a Synechocystis strain that lacks the endogenous, cyanobacterial lycopene cyclase cruA. The resulting synlut strain showed wild-type growth and only moderate changes in total pigment composition under mixotrophic conditions, indicating that the cruA deficiency can be complemented by Arabidopsis lycopene cyclases leaving the endogenous ß-branch intact. A combination of liquid chromatography, UV-Vis detection and mass spectrometry confirmed a low but distinct synthesis of lutein at rates of 4.8 ± 1.5 nmol per liter culture at OD730 (1.03 ± 0.47 mmol mol-1 chlorophyll). In conclusion, synlut provides a suitable platform to study the α-branch of the plastidic MEP pathway and other functions related to lutein in a cyanobacterial host system.

Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria.

Cyanobacteria must prevent imbalances between absorbed light energy (source) and the metabolic capacity (sink) to utilize it to protect their photosynthetic apparatus against damage. A number of photoprotective mechanisms assist in dissipating excess absorbed energy, including respiratory terminal oxidases and flavodiiron proteins, but inherently reduce photosynthetic efficiency. Recently, it has been hypothesized that some engineered metabolic pathways may improve photosynthetic performance by correcting source/sink imbalances. In the context of this subject, we explored the interconnectivity between endogenous electron valves, and the activation of one or more heterologous metabolic sinks. We coexpressed two heterologous metabolic pathways that have been previously shown to positively impact photosynthetic activity in cyanobacteria, a sucrose production pathway (consuming ATP and reductant) and a reductant-only consuming cytochrome P450. Sucrose export was associated with improved quantum yield of phtotosystem II (PSII) and enhanced electron transport chain flux, especially at lower illumination levels, while cytochrome P450 activity led to photosynthetic enhancements primarily observed under high light. Moreover, coexpression of these two heterologous sinks showed additive impacts on photosynthesis, indicating that neither sink alone was capable of utilizing the full "overcapacity" of the electron transport chain. We find that heterologous sinks may partially compensate for the loss of photosystem I (PSI) oxidizing mechanisms even under rapid illumination changes, although this compensation is incomplete. Our results provide support for the theory that heterologous metabolism can act as a photosynthetic sink and exhibit some overlapping functionality with photoprotective mechanisms, while potentially conserving energy within useful metabolic products that might otherwise be "lost."

Cytochrome c6 is the main respiratory and photosynthetic soluble electron donor in heterocysts of the cyanobacterium Anabaena sp. PCC 7120.

Cytochrome c6 is a soluble electron carrier, present in all known cyanobacteria, that has been replaced by plastocyanin in plants. Despite their high structural differences, both proteins have been reported to be isofunctional in cyanobacteria and green algae, acting as alternative electron carriers from the cytochrome b6-f complex to photosystem I or terminal oxidases. We have investigated the subcellular localization of both cytochrome c6 and plastocyanin in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 grown in the presence of combined nitrogen and under diazotrophic conditions. Our studies conclude that cytochrome c6 is expressed at significant levels in heterocysts, even in the presence of copper, condition in which it is strongly repressed in vegetative cells. However, the copper-dependent regulation of plastocyanin is not altered in heterocysts. In addition, in heterocysts, cytochrome c6 has shown to be the main soluble electron carrier to cytochrome c oxidase-2 in respiration. A cytochrome c6 deletion mutant is unable to grow under diazotrophic conditions in the presence of copper, suggesting that cytochrome c6 plays an essential role in the physiology of heterocysts that cannot be covered by plastocyanin.

Cyt c6-3: A New Isoform of Photosynthetic Cyt c6 Exclusive to Heterocyst-Forming Cyanobacteria.

All known cyanobacteria contain Cyt c6, a small soluble electron carrier protein whose main function is to transfer electrons from the Cyt b6f complex to PSI, although it is also involved in respiration. We have previously described a second isoform of this protein, the Cyt c6-like, whose function remains unknown. Here we describe a third isoform of Cyt c6 (here called Cytc6-3), which is only found in heterocyst-forming filamentous cyanobacteria. Cyt c6-3 is expressed in vegetative cells but is specifically repressed in heterocysts cells under diazotrophic growth conditions. Although there is a close structural similarity between Cyt c6-3 and Cyt c6 related to the general protein folding, Cyt c6-3 presents differential electrostatic surface features as compared with Cyt c6, its expression is not copper dependent and has a low reactivity towards PSI. According to the different expression pattern, functional reactivity and structural properties, Cyt c6-3 has to play an as yet to be defined regulatory role related to heterocyst differentiation.

In vivo reconstitution of a homodimeric cytochrome b559 like structure: The role of the N-terminus α-subunit from Synechocystis sp. PCC 6803.

The cytochrome b559 is a heme-bridged heterodimeric protein with two subunits, α and ß. Both subunits from Synechocystis sp. PCC 6803 have previously been cloned and overexpressed in Escherichia coli and in vivo reconstitution experiments have been carried out. The formation of homodimers in the bacterial membrane with endogenous heme was only observed in the case of the ß-subunit (ß/ß) but not with the full length α-subunit. In the present work, reconstitution of a homodimer (α/α) cytochrome b559 like structure was possible using a chimeric N-terminus α-subunit truncated before the amino acid isoleucine 17, eliminating completely a short amphipathic α-helix that lays on the surface of the membrane. Overexpression and in vivo reconstitution in the bacteria was clearly demonstrated by the brownish color of the culture pellet and the use of a commercial monoclonal antibody against the fusion protein carrier, the maltoside binding protein, and polyclonal antibodies against a synthetic peptide of the α-subunit from Thermosynechococcus elongatus. Moreover, a simple partial purification after membrane solubilization with Triton X-100 confirmed that the overexpressed protein complex corresponded with the maltoside binding protein-chimeric α-subunit cytochrome b559 like structure. The features of the new structure were determined by UV-Vis, electron paramagnetic resonance and redox potentiometric techniques. Ribbon representations of all possible structures are also shown to better understand the mechanism of the cytochrome b559 maturation in the bacterial cytoplasmic membrane.

[Adenocarcinoma arising in Meckel's diverticulum: a case report and literature review]. / Adenocarcinoma sobre divertículo de Meckel: presentación de un caso y revisión de la literatura.

Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract. The presence of malignant lesions arising in the diverticulum is very rare, the most common malignant lesion being sarcoma, followed by carcinoid tumors, and less frequently by adenocarcinomas. We present the case of an 86-year-old man who developed acute abdomen. Surgery revealed a perforated Meckel's diverticulum. Histology identified a poorly-differentiated adenocarcinoma arising in Meckel's diverticulum. We provide a review of the literature.

Adenocarcinoma sobre divertículo de Meckel: presentación de un caso y revisión de la literatura / Adenocarcinoma arising in Meckel’s diverticulum: a case report and literature review

Resumen El divertículo de Meckel es la anomalía congénita más común del tracto gastrointestinal. La presencia de lesiones malignas sobre el divertículo es muy infrecuente, la más común corresponde a los sarcomas, seguidas del tumor carcinoide y, por último, de los adenocarcinomas. Presentamos el caso de un paciente de 86 años intervenido por un cuadro de abdomen agudo; en la cirugía se identificó un divertículo de Meckel perforado, la histología demostró un adenocarcinoma pobremente diferenciado. Finalmente se ha realizado una revisión de la literatura médica relacionada (AU)

Abstract Meckel’s diverticulum is the most common congenital anomaly of the gastrointestinaltract. The presence of malignant lesions arising in the diverticulum is very rare, themost common malignant lesion being sarcoma, followed by carcinoid tumors, and less frequentlyby adenocarcinomas. We present the case of an 86-year-old man who developed acuteabdomen. Surgery revealed a perforated Meckel’s diverticulum. Histology identified a poorly differentiated adenocarcinoma arising in Meckel’s diverticulum. We provide a review of theliterature

Metástasis colónica de carcinoma lobulillar de mama / Colon metastasis of lobular breast cancer

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Adrenalectomía laparoscópica: presentación de 43 casos / Laparoscopic adrenalectomy: Presentation of 43 cases

Introducción El propósito del estudio es exponer y analizar nuestra experiencia en adrenalectomía laparoscópica (AL).Material y métodos Estudio descriptivo y retrospectivo sobre AL realizada en nuestro centro desde enero de 2000 hasta diciembre de 2008.ResultadosSe realizaron un total de 43 AL a 41 pacientes mediante abordaje transperitoneal lateral. La mediana de edad de los pacientes intervenidos se situó en 53 años. La principal indicación en frecuencia de nuestra serie fue el hiperaldosteronismo (19), seguido de incidentalomas (8), feocromocitomas (6), síndrome de Cushing (6), lesiones metastásicas (3) y carcinoma suprarrenal primario (1). La media de estancia hospitalaria poscirugía fue de 3 días y la media del tamaño de las masas fue de 30mm (rango: 4–155mm). No hubo mortalidad en nuestra serie. La necesidad de conversión se redujo a un caso; en ningún caso fue necesario reintervenir a un paciente. ConclusionesLa AL es una técnica segura y eficaz en el tratamiento de tumores suprarrenales que puede realizarse con riesgo y morbilidad mínima (AU)

Introduction The aim of the study was to present and analyse our experience in laparoscopic adrenalectomy (LA).Materials and methods Descriptive and retrospective study including LA performed over 8 years, between 2000 and 2008 in our hospital. Results A total of 43 LA were performed to 41 patients using a transperitoneal lateral approach. Indications for adrenalectomy included hyperaldosteronism (19), non-functioning adenoma (8), phaeochromocytoma (6), Cushing's syndrome (6), metastasis (3) and adrenal primary tumour (1). Median postoperative hospital stay was 3 days and the median size of the masses was 30mm (range: 4–155mm) Complications occurred in 3 patients (2 respiratory infections, and 1 intraoperative bleeding). There was no mortality. Only one case needed conversion to open adrenalectomy; no patients required reintervention. Conclusion Laparoscopic adrenalectomy is a safe and effective method in the treatment of adrenal masses and it can be performed with minimal risk and morbidity (AU)

[Laparoscopic adrenalectomy: presentation of 43 cases]. / Adrenalectomía laparoscópica: presentación de 43 casos.

INTRODUCTION: The aim of the study was to present and analyse our experience in laparoscopic adrenalectomy (LA). MATERIALS AND METHODS: Descriptive and retrospective study including LA performed over 8 years, between 2000 and 2008 in our hospital. RESULTS: A total of 43 LA were performed to 41 patients using a transperitoneal lateral approach. Indications for adrenalectomy included hyperaldosteronism (19), non-functioning adenoma (8), phaeochromocytoma (6), Cushing's syndrome (6), metastasis (3) and adrenal primary tumour (1). Median postoperative hospital stay was 3 days and the median size of the masses was 30mm (range: 4-155mm) Complications occurred in 3 patients (2 respiratory infections, and 1 intraoperative bleeding). There was no mortality. Only one case needed conversion to open adrenalectomy; no patients required reintervention. CONCLUSION: Laparoscopic adrenalectomy is a safe and effective method in the treatment of adrenal masses and it can be performed with minimal risk and morbidity.