Minimal and hybrid hydrogenases are active from archaea.

Microbial hydrogen (H2) cycling underpins the diversity and functionality of diverse anoxic ecosystems. Among the three evolutionarily distinct hydrogenase superfamilies responsible, [FeFe] hydrogenases were thought to be restricted to bacteria and eukaryotes. Here, we show that anaerobic archaea encode diverse, active, and ancient lineages of [FeFe] hydrogenases through combining analysis of existing and new genomes with extensive biochemical experiments. [FeFe] hydrogenases are encoded by genomes of nine archaeal phyla and expressed by H2-producing Asgard archaeon cultures. We report an ultraminimal hydrogenase in DPANN archaea that binds the catalytic H-cluster and produces H2. Moreover, we identify and characterize remarkable hybrid complexes formed through the fusion of [FeFe] and [NiFe] hydrogenases in ten other archaeal orders. Phylogenetic analysis and structural modeling suggest a deep evolutionary history of hybrid hydrogenases. These findings reveal new metabolic adaptations of archaea, streamlined H2 catalysts for biotechnological development, and a surprisingly intertwined evolutionary history between the two major H2-metabolizing enzymes.

Autotrophic biofilms sustained by deeply sourced groundwater host diverse bacteria implicated in sulfur and hydrogen metabolism.

BACKGROUND: Biofilms in sulfide-rich springs present intricate microbial communities that play pivotal roles in biogeochemical cycling. We studied chemoautotrophically based biofilms that host diverse CPR bacteria and grow in sulfide-rich springs to investigate microbial controls on biogeochemical cycling. RESULTS: Sulfide springs biofilms were investigated using bulk geochemical analysis, genome-resolved metagenomics, and scanning transmission X-ray microscopy (STXM) at room temperature and 87 K. Chemolithotrophic sulfur-oxidizing bacteria, including Thiothrix and Beggiatoa, dominate the biofilms, which also contain CPR Gracilibacteria, Absconditabacteria, Saccharibacteria, Peregrinibacteria, Berkelbacteria, Microgenomates, and Parcubacteria. STXM imaging revealed ultra-small cells near the surfaces of filamentous bacteria that may be CPR bacterial episymbionts. STXM and NEXAFS spectroscopy at carbon K and sulfur L2,3 edges show that filamentous bacteria contain protein-encapsulated spherical elemental sulfur granules, indicating that they are sulfur oxidizers, likely Thiothrix. Berkelbacteria and Moranbacteria in the same biofilm sample are predicted to have a novel electron bifurcating group 3b [NiFe]-hydrogenase, putatively a sulfhydrogenase, potentially linked to sulfur metabolism via redox cofactors. This complex could potentially contribute to symbioses, for example, with sulfur-oxidizing bacteria such as Thiothrix that is based on cryptic sulfur cycling. One Doudnabacteria genome encodes adjacent sulfur dioxygenase and rhodanese genes that may convert thiosulfate to sulfite. We find similar conserved genomic architecture associated with CPR bacteria from other sulfur-rich subsurface ecosystems. CONCLUSIONS: Our combined metagenomic, geochemical, spectromicroscopic, and structural bioinformatics analyses of biofilms growing in sulfide-rich springs revealed consortia that contain CPR bacteria and sulfur-oxidizing Proteobacteria, including Thiothrix, and bacteria from a new family within Beggiatoales. We infer roles for CPR bacteria in sulfur and hydrogen cycling. Video Abstract.

Rubisco Function, Evolution, and Engineering.

Carbon fixation is the process by which CO2 is converted from a gas into biomass. The Calvin-Benson-Bassham cycle (CBB) is the dominant carbon-consuming pathway on Earth, driving >99.5% of the ∼120 billion tons of carbon that are converted to sugar by plants, algae, and cyanobacteria. The carboxylase enzyme in the CBB, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), fixes one CO2 molecule per turn of the cycle into bioavailable sugars. Despite being critical to the assimilation of carbon, rubisco's kinetic rate is not very fast, limiting flux through the pathway. This bottleneck presents a paradox: Why has rubisco not evolved to be a better catalyst? Many hypothesize that the catalytic mechanism of rubisco is subject to one or more trade-offs and that rubisco variants have been optimized for their native physiological environment. Here, we review the evolution and biochemistry of rubisco through the lens of structure and mechanism in order to understand what trade-offs limit its improvement. We also review the many attempts to improve rubisco itself and thereby promote plant growth.

Borgs are giant genetic elements with potential to expand metabolic capacity.

Anaerobic methane oxidation exerts a key control on greenhouse gas emissions1, yet factors that modulate the activity of microorganisms performing this function remain poorly understood. Here we discovered extraordinarily large, diverse DNA sequences that primarily encode hypothetical proteins through studying groundwater, sediments and wetland soil where methane production and oxidation occur. Four curated, complete genomes are linear, up to approximately 1 Mb in length and share genome organization, including replichore structure, long inverted terminal repeats and genome-wide unique perfect tandem direct repeats that are intergenic or generate amino acid repeats. We infer that these are highly divergent archaeal extrachromosomal elements with a distinct evolutionary origin. Gene sequence similarity, phylogeny and local divergence of sequence composition indicate that many of their genes were assimilated from methane-oxidizing Methanoperedens archaea. We refer to these elements as 'Borgs'. We identified at least 19 different Borg types coexisting with Methanoperedens spp. in four distinct ecosystems. Borgs provide methane-oxidizing Methanoperedens archaea access to genes encoding proteins involved in redox reactions and energy conservation (for example, clusters of multihaem cytochromes and methyl coenzyme M reductase). These data suggest that Borgs might have previously unrecognized roles in the metabolism of this group of archaea, which are known to modulate greenhouse gas emissions, but further studies are now needed to establish their functional relevance.

The Effort-Reward Model and Its Effect on Burnout Among Nurses in Ecuador.

Burnout has harmful consequences for individuals and organizations. The study of its antecedents can help us to manage and prevent it. This research aims to explore the role of the effort-reward imbalance (ERI) model as well as the mediation of the working experience in the burnout processes. For this purpose, we have conducted a study in 629 employees from two hospitals in the city of Guayaquil (Ecuador). For this study, the Spanish version of the Maslach Burnout Inventory was applied, as well as the ERI Questionnaire, along with other socio-demographical and occupational variables. A statistical analysis was performed with the obtained data, using structural equation models (SEMs). Results showed that employee effort has a stronger and statistically significant direct effect on emotional burnout, whereas the perception of the obtained reward also had this effect but indirectly in a negative sense, with job experience as a mediating variable.

Patterns of Gene Content and Co-occurrence Constrain the Evolutionary Path toward Animal Association in Candidate Phyla Radiation Bacteria.

Candidate Phyla Radiation (CPR) bacteria are small, likely episymbiotic organisms found across Earth's ecosystems. Despite their prevalence, the distribution of CPR lineages across habitats and the genomic signatures of transitions among these habitats remain unclear. Here, we expand the genome inventory for Absconditabacteria (SR1), Gracilibacteria, and Saccharibacteria (TM7), CPR bacteria known to occur in both animal-associated and environmental microbiomes, and investigate variation in gene content with habitat of origin. By overlaying phylogeny with habitat information, we show that bacteria from these three lineages have undergone multiple transitions from environmental habitats into animal microbiomes. Based on co-occurrence analyses of hundreds of metagenomes, we extend the prior suggestion that certain Saccharibacteria have broad bacterial host ranges and constrain possible host relationships for Absconditabacteria and Gracilibacteria. Full-proteome analyses show that animal-associated Saccharibacteria have smaller gene repertoires than their environmental counterparts and are enriched in numerous protein families, including those likely functioning in amino acid metabolism, phage defense, and detoxification of peroxide. In contrast, some freshwater Saccharibacteria encode a putative rhodopsin. For protein families exhibiting the clearest patterns of differential habitat distribution, we compared protein and species phylogenies to estimate the incidence of lateral gene transfer and genomic loss occurring over the species tree. These analyses suggest that habitat transitions were likely not accompanied by large transfer or loss events but rather were associated with continuous proteome remodeling. Thus, we speculate that CPR habitat transitions were driven largely by availability of suitable host taxa and were reinforced by acquisition and loss of some capacities. IMPORTANCE Studying the genetic differences between related microorganisms from different environment types can indicate factors associated with their movement among habitats. This is particularly interesting for bacteria from the Candidate Phyla Radiation because their minimal metabolic capabilities require associations with microbial hosts. We found that shifts of Absconditabacteria, Gracilibacteria, and Saccharibacteria between environmental ecosystems and mammalian mouths/guts probably did not involve major episodes of gene gain and loss; rather, gradual genomic change likely followed habitat migration. The results inform our understanding of how little-known microorganisms establish in the human microbiota where they may ultimately impact health.

Tubular colonic duplication in an adult patient with long-standing history of constipation and tenesmus.

BACKGROUND: Intestinal duplications are rare congenital developmental anomalies with an incidence of 0.005-0.025% of births. They are usually identified before 2 years of age and commonly affect the foregut or mid-/hindgut. However, it is very uncommon for these anomalies, to arise in the colon or present during adulthood. CASE PRESENTATION: Herein, we present a case of a 28-year-old woman with a long-standing history of constipation, tenesmus, and rectal prolapse. Colonoscopy results were normal. An abdominal computed tomography (CT) revealed a diffusely mildly dilated redundant colon, which was prominently stool-filled. The gastrografin enema showed ahaustral mucosal appearance of the sigmoid and descending colon with findings suggestive of tricompartmental pelvic floor prolapse, moderate-size anterior rectocele, and grade 2 sigmoidocele. A laparoscopic exploration was performed, revealing a tubular duplicated colon at the sigmoid level. A sigmoid resection rectopexy was performed. Pathologic examination supported the diagnosis. At 1-month follow-up, the patient was doing well without constipation or rectal prolapse. CONCLUSIONS: Tubular colonic duplications are very rare in adults but should be considered in the differential diagnosis of chronic constipation refractory to medical therapy. Due to the non-specific manifestations of this entity, it is rather challenging to make an accurate diagnosis pre-operatively. Surgery remains the mainstay of treatment. Some reports suggest that carcinomas are more prone to develop in colonic/rectal duplications than in other GI tract duplications.

Discovery and characterization of a novel family of prokaryotic nanocompartments involved in sulfur metabolism.

Prokaryotic nanocompartments, also known as encapsulins, are a recently discovered proteinaceous organelle-like compartment in prokaryotes that compartmentalize cargo enzymes. While initial studies have begun to elucidate the structure and physiological roles of encapsulins, bioinformatic evidence suggests that a great diversity of encapsulin nanocompartments remains unexplored. Here, we describe a novel encapsulin in the freshwater cyanobacterium Synechococcus elongatus PCC 7942. This nanocompartment is upregulated upon sulfate starvation and encapsulates a cysteine desulfurase enzyme via an N-terminal targeting sequence. Using cryo-electron microscopy, we have determined the structure of the nanocompartment complex to 2.2 Å resolution. Lastly, biochemical characterization of the complex demonstrated that the activity of the cysteine desulfurase is enhanced upon encapsulation. Taken together, our discovery, structural analysis, and enzymatic characterization of this prokaryotic nanocompartment provide a foundation for future studies seeking to understand the physiological role of this encapsulin in various bacteria.

Variation for Composition and Quality in a Collection of the Resilient Mediterranean 'de penjar' Long Shelf-Life Tomato Under High and Low N Fertilization Levels.

The 'de penjar' tomato (Solanum lycopersicum L.) is a group of local varieties from the Spanish Mediterranean region carrying the alc mutation, which provides long shelf-life. Their evolution under low-input management practices has led to the selection of resilient genotypes to adverse conditions. Here we present the first evaluation on nutritional fruit composition of a collection of 44 varieties of 'de penjar' tomato under two N fertilization levels, provided by doses of manure equivalent to 162 kg N ha-1 in the high N treatment and 49 kg N ha-1 in the low N treatment. Twenty-seven fruit composition and quality traits, as well as plant yield and SPAD value, were evaluated. A large variation was observed, with lycopene being the composition trait with the highest relative range of variation (over 4-fold) under both N treatments, and significant differences among varieties were detected for all traits. While yield and most quality traits were not affected by the reduction in N fertilization, fruits from the low N treatment had, on average, higher values for hue (5.9%) and lower for fructose (-11.5%), glucose (-15.8%), and total sweetness index (-12.9%). In addition, lycopene and ß-carotene presented a strongly significant genotype × N input interaction. Local varieties had higher values than commercial varieties for traits related to the ratio of sweetness to acidity and for vitamin C, which reinforces the appreciation for their organoleptic and nutritional quality. Highest-yielding varieties under both conditions displayed wide variation in the composition and quality profiles, which may allow the selection of specific ideotypes with high quality under low N conditions. These results revealed the potential of 'de penjar' varieties as a genetic resource in breeding for low N inputs and improving the organoleptic and nutritional tomato fruit quality.

Tubular colonic duplication in an adult patient with long-standing history of constipation and tenesmus

Background Intestinal duplications are rare congenital developmental anomalies with an incidence of 0.005-0.025% of births. They are usually identified before 2 years of age and commonly affect the foregut or mid-/hindgut. However, it is very uncommon for these anomalies, to arise in the colon or present during adulthood. Case presentation Herein, we present a case of a 28-year-old woman with a long-standing history of constipation, tenesmus, and rectal prolapse. Colonoscopy results were normal. An abdominal computed tomography (CT) revealed a diffusely mildly dilated redundant colon, which was prominently stool-filled. The gastrografin enema showed ahaustral mucosal appearance of the sigmoid and descending colon with findings suggestive of tricompartmental pelvic floor prolapse, moderate-size anterior rectocele, and grade 2 sigmoidocele. A laparoscopic exploration was performed, revealing a tubular duplicated colon at the sigmoid level. A sigmoid resection rectopexy was performed. Pathologic examination supported the diagnosis. At 1-month follow-up, the patient was doing well without constipation or rectal prolapse. Conclusions Tubular colonic duplications are very rare in adults but should be considered in the differential diagnosis of chronic constipation refractory to medical therapy. Due to the non-specific manifestations of this entity, it is rather challenging to make an accurate diagnosis pre-operatively. Surgery remains the mainstay of treatment. Some reports suggest that carcinomas are more prone to develop in colonic/rectal duplications than in other GI tract duplications.

Cifoescoliosis severa secundaria a neurofibromatosis. Presentación de un caso / Severe kyphoscoliosis secondary to neurofibromatosis. Case presentation

La escoliosis distrófica de la neurofibromatosis se caracteriza por ser una cifoescoliosis de ángulo agudo que compromete un segmento corto de la columna vertebral y genera una gran deformidad que, sumada a los cambios distróficos de la columna, convierte a los gestos quirúrgicos para su corrección en verdaderos retos. Se presenta a un varón de 15 años con cifoescoliosis toracolumbar distrófica severa con ápice en T9, ángulo de Cobb 107° de escoliosis y 110,7° de cifosis segmentaria. Se realiza una cirugía por vía posterior en tres tiempos, mediante una resección de la columna vertebral y reemplazo con malla de titanio; se logra una corrección de la cifosis y la escoliosis del 56% y 59,8%, respectivamente. El paciente no tuvo complicaciones mayores, ni secuelas, y la evolución fue favorable. La resección de la columna vertebral es una técnica quirúrgica potente y desafiante para el manejo de la deformidad cifoescoliótica compleja necesaria para lograr el equilibrio espinal, aunque no está exenta de complicaciones, sobre todo neurológicas y pulmonares, a veces, inevitables. La calidad de vida de nuestro paciente tuvo una mejoría importante. Nivel de Evidencia: IV

Dystrophic scoliosis in neurofibromatosis is identifiable by being an acuteangle kyphoscoliosis involving a short segment of the spine and producing severe deformity that when associated with the dystrophic changes of the spine result in real surgical challenges. We report the clinical case of a 15-year male with severe dystrophic kyphoscoliosis at the thoracolumbar area, with apex at T9, scoliosis with a Cobb angle of 107 °, and segmental kyphosis of 110.7°. The patient underwent a three-stage surgery, performed through a posterior approach, involving a vertebral column resection (VCR) and titanium mesh replacement, and achieving a kyphosis correction of 56% and a scoliosis correction of 59.8%. The patient experienced no major complications nor sequelae and had a favorable course. The VCR is a powerful and demanding surgical technique that allows for the management of the complex kyphoscoliosis deformity to achieve spinal balance; however, it is not without complications, especially neurological and pulmonary complications, which may be unavoidable. Our patient's quality of life has improved significantly. Level of Evidence: IV

Prevalencia de las cardiopatías congénitas en el Hospital Escuela Oscar Danilo Rosales durante el período de enero 1995 - diciembre 1999 / Prevalence of the congenital heart diseases in the hospital Escuela Oscar Danilo Rosales during the period of january 1995 to december of 1999

Se realizó un estudio de corte transversal a todos los recién nacidos vivos, en el Hospital Escuela "Oscar Danilo Rosales Argüello" (HEODRA), durante el período 1995-1999, que fueron dignósticados con cardiopatía congénita. El universo estuvo constituido por un total de 25,269 recién nacidos de los cuales se encontraron 80 pacientes con diagnóstico de cardiopatía congénita,el 55 porciento de los niños estudiados pertenecián al sexo masculino, y el 45 porciento al sexo femenino, el grupo de edad que prevalecio fue de 28 días, 11 meses con un 45 porciento, seguido del grupo de 1-4 años con 35 porciento y 11 porciento el de edad neonatal tardia. El tipo de cardiopatía más frecuente fue la comunicación interventricular, la que se complicó en un 98 porciento de los casos con neumonía, 53 porciento con insuficiencia cardiaca. Del total de pacientes con cardiopatía congénita, 9 presentaron malformaciones congénitas no cardiacas,lo que equivale a un 11 porciento del total de los pacientes encontrados de los cuales el 44 porciento presentó Sindrome de Down, 33 porciento Labio Leporino y 11 porciento presentó Paladar Hendido y Fisura Labial. El grupo etareo donde hubo más muertes, fue el de la edad neonatal temprana con 40 porciento seguido del de edad neonatal tardía y el de 28 días a 11 meses con 30 porciento ambos grupos, el tipo de cardiopatía que predominó en los pacientes fallecidos fue la comunicación interventricular con 60 porciento, seguido de los pacientes con cardiopatías congénitas mixtas con 30 porciento, de los cuales dos pacientes presentaron comunicación interventricular más persistencias del conducto arterioso y un paciente comunicación interventricular más comunicación interauricular