Sulfate-reducing bacteria are characterized by a high number of hydrogenases, which have been proposed to contribute to the overall energy metabolism of the cell, but exactly in what role is not clear. Desulfovibrio spp. can produce or consume H 2 when growing on organic or inorganic substrates in the presence or absence of sulfate. Because of the presence of only two hydrogenases encoded in its genome, the periplasmic HynAB and cytoplasmic Ech hydrogenases, Desulfovibrio gigas is an excellent model organism for investigation of the specific function of each of these enzymes during growth. In this study, we analyzed the physiological response to the deletion of the genes that encode the two hydrogenases in D. gigas, through the generation of ⌬echBC and ⌬hynAB single mutant strains. These strains were analyzed for the ability to grow on different substrates, such as lactate, pyruvate, and hydrogen, under respiratory and fermentative conditions. Furthermore, the expression of both hydrogenase genes in the three strains studied was assessed through quantitative reverse transcription-PCR. The results demonstrate that neither hydrogenase is essential for growth on lactate-sulfate, indicating that hydrogen cycling is not indispensable. In addition, the periplasmic HynAB enzyme has a bifunctional activity and is required for growth on H 2 or by fermentation of pyruvate. Therefore, this enzyme seems to play a dominant role in D. gigas hydrogen metabolism. Hydrogenases are key enzymes in the hydrogen metabolism of Desulfovibrio spp. that catalyze the reversible oxidation of molecular hydrogen into protons and electrons (1). However, their role during sulfate respiration has not been clearly established. Odom and Peck proposed a hydrogen cycling model to explain energy conservation during growth on lactate and sulfate by Desulfovibrio spp., which belong to the deltaproteobacteria subgroup of the sulfate-reducing bacteria (SRB) (2). The model predicts that protons and electrons produced in the oxidation of lactate are used for the production of molecular hydrogen by a cytoplasmic hydrogenase. This hydrogen then diffuses across the membrane to the periplasm, where it is reoxidized by a periplasmic hydrogenase. Electrons are transferred back to the cytoplasm for sulfate reduction, thus creating a proton gradient across the membrane that leads to ATP formation. In this model, the presence of at least two hydrogenases on opposite sides of the membrane is a requirement for growth. In contrast, other studies suggested that the physiological role of these enzymes was to regulate the redox potential of the cell, controlling the flow of protons and electrons and generating a proton motive force (3). More recent models, proposed for Desulfovibrio vulgaris, suggested dual pathways for electron transfer from lactate to sulfate, one involving the cycling of H 2 and the other a route involving a membrane-associated electron transfer chain (4, 5). Several membrane complexes have been identified in SRB that could be involved in this proce...

HighlightsDesulfovibrio gigas genome encodes two HcpR paralogs, HcpR1 and HcpR2.Cells lacking HcpR1 are less tolerant to NO.HcpR1 regulates the expression of several genes related to nitrogen metabolism.Phylogenetic analyses indicate that the presence of HcpR paralogs is a common finding among Desulfovibrio species.

Desulfovibrio gigas is a model organism of sulfate-reducing bacteria of which energy metabolism and stress response have been extensively studied. The complete genomic context of this organism was however, not yet available. The sequencing of the D. gigas genome provides insights into the integrated network of energy conserving complexes and structures present in this bacterium. Comparison with genomes of other Desulfovibrio spp. reveals the presence of two different CRISPR/Cas systems in D. gigas. Phylogenetic analysis using conserved protein sequences (encoded by rpoB and gyrB) indicates two main groups of Desulfovibrio spp, being D. gigas more closely related to D. vulgaris and D. desulfuricans strains. Gene duplications were found such as those encoding fumarate reductase, formate dehydrogenase, and superoxide dismutase. Complexes not yet described within Desulfovibrio genus were identified: Mnh complex, a v-type ATP-synthase as well as genes encoding the MinCDE system that could be responsible for the larger size of D. gigas when compared to other members of the genus. A low number of hydrogenases and the absence of the codh/acs and pfl genes, both present in D. vulgaris strains, indicate that intermediate cycling mechanisms may contribute substantially less to the energy gain in D. gigas compared to other Desulfovibrio spp. This might be compensated by the presence of other unique genomic arrangements of complexes such as the Rnf and the Hdr/Flox, or by the presence of NAD(P)H related complexes, like the Nuo, NfnAB or Mnh.

The biofortification, process of nutrients creation for food crops, provides a sustainable strategy for rural populations in developing countries. Crops are created for greater levels of micronutrients, by using conventional and transgenic breeding methods. Recent studies provide evidence that biofortification is a promising strategy to combat nutritional deficits. Being a basic and common food of the population of developing countries, the flour got a significant attention as appropriate matrix for biofortification.

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Selenium is an antioxidant trace mineral with important biochemical functions related to the enzymatic activity of selenoproteins. Due to a wide variation in the content of selenium from different plant sources, there is a high risk of deficiency of this nutrient in human nutrition, and particularly in the early childhood. Thus, the use of biofortified staple foods, namely selenium rice flour can be understood as an important trait, namely for food production for infants. This study aims to evaluate the importance of selenium biofortified rice flour, further considering baby foods.

<b><i>Background:</i></b>The relationship between exposure to asbestos and malignant pleural mesothelioma (MPM) is already well established. Nevertheless, much remains to be known about exposure thereto and the incidence and mortality from MPM. <b><i>Objective:</i></b> This systematic review aims to map the relationship between asbestos and MPM by studying the exposure to asbestos and the incidence and mortality of MPM. <b><i>Methods:</i></b> A systematic review was conducted relating asbestos and MPM. Exposure to asbestos, incidence, and mortality by MPM was reviewed. PubMed, Web of Science, Cochrane Library, RCAAP, DART-Europe, and the reference lists of included studies were searched, from January 1, 1960, to December 31, 2020. Methodological quality was checked, the risk of bias analysis was performed, a level of evidence grade was assigned, and descriptive data analysis was performed. <b><i>Results:</i></b> 3,484 unique citations were identified, which included seventeen observational studies that met inclusion criteria with a total of 1,104 patients. Heterogeneity is present between the included studies which range from a case series of 16 retrospective studies and 1 prospective study. Studies were mostly conducted in Europe, particularly in Italy (6), and were published between 1969 and 2020. The mean age of patients is approximately 66 years with a latency period between the first exposure and diagnosis of approximately 42 years. 14 studies present data regarding the occupational context and chrysotile and crocidolite are the most studied types of fibre. The incidence of cases occurred between the interval 1966 and 2014 and in 9 studies the mortality rate was 100% of patients. <b><i>Conclusion:</i></b> There is high evidence to support the relationships between asbestos and MPM. However, the relatively scant information provided by the studies reinforces the need for well-conducted research and implementation of National Mesothelioma Surveillance Centres at a global level.

Medication errors represent a concern for healthcare organizations due to their negative consequences. In the nursing context, these errors represent a threat to the quality of care and patient safety. Many factors have been identified as potential causes for these errors in intensive care units. A scoping review will be developed to identify interventions/strategies to minimize the occurrence of medication errors by nurses, considering the Joanna Briggs Institute (JBI) methodology. A search will be conducted in the EbscoHost (CINAHL Complete and MEDLINE), Embase and PubMed databases. Data analysis, extraction and synthesis will be carried out by two reviewers independently. This review will attempt to map which interventions are more specific to minimizing medication error by nurses in intensive care and to recognize which factors influence this type of error to mitigate practices that may lead to error. This protocol acts as the framework for a scoping review in the strategy to map the interventions and which factors contribute to the medication error by intensive care nurses. This study was prospectively registered with the Open Science Framework on 21 April 2023 with registration number DOI 10.17605/OSF.IO/94KH3.