Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements

Self splicing introns and inteins that rely on a homing endonuclease for propagation are parasitic genetic elements. Their life-cycle and evolutionary fate has been described through the homing cycle. According to this model the homing endonuclease is selected for function only during the spreading phase of the parasite. This phase ends when the parasitic element is fixed in the population. Upon fixation the homing endonuclease is no longer under selection, and its activity is lost through random processes. Recent analyses of these parasitic elements with functional homing endonucleases suggest that this model in its most simple form is not always applicable. Apparently, functioning homing endonuclease can persist over long evolutionary times in populations and species that are thought to be asexual or nearly asexual. Here we review these recent findings and discuss their implications. Reasons for the long-term persistence of a functional homing endonuclease include: More recombination (sexual and as a result of gene transfer) than previously assumed for these organisms; complex population structures that prevent the element from being fixed; a balance between active spreading of the homing endonuclease and a decrease in fitness caused by the parasite in the host organism; or a function of the homing endonuclease that increases the fitness of the host organism and results in purifying selection for the homing endonuclease activity, even after fixation in a local population. In the future, more detailed studies of the population dynamics of the activity and regulation of homing endonucleases are needed to decide between these possibilities, and to determine their relative contributions to the long term survival of parasitic genes within a population. Two outstanding publications on the amoeba Naegleria group I intron (Wikmark et al. BMC Evol Biol 2006, 6:39) and the PRP8 inteins in ascomycetes (Butler et al.BMC Evol Biol 2006, 6:42) provide important stepping stones towards integrated studies on how these parasitic elements evolve through time together with, or despite, their hosts

The intein of the Thermoplasma A-ATPase A subunit: Structure, evolution and expression in E. coli

BACKGROUND: Inteins are selfish genetic elements that excise themselves from the host protein during post translational processing, and religate the host protein with a peptide bond. In addition to this splicing activity, most reported inteins also contain an endonuclease domain that is important in intein propagation. RESULTS: The gene encoding the Thermoplasma acidophilum A-ATPase catalytic subunit A is the only one in the entire T. acidophilum genome that has been identified to contain an intein. This intein is inserted in the same position as the inteins found in the ATPase A-subunits encoding gene in Pyrococcus abyssi, P. furiosus and P. horikoshii and is found 20 amino acids upstream of the intein in the homologous vma-1 gene in Saccharomyces cerevisiae. In contrast to the other inteins in catalytic ATPase subunits, the T. acidophilum intein does not contain an endonuclease domain. T. acidophilum has different codon usage frequencies as compared to Escherichia coli. Initially, the low abundance of rare tRNAs prevented expression of the T. acidophilum A-ATPase A subunit in E. coli. Using a strain of E. coli that expresses additional tRNAs for rare codons, the T. acidophilum A-ATPase A subunit was successfully expressed in E. coli. CONCLUSIONS: Despite differences in pH and temperature between the E. coli and the T. acidophilum cytoplasms, the T. acidophilum intein retains efficient self-splicing activity when expressed in E. coli. The small intein in the Thermoplasma A-ATPase is closely related to the endonuclease containing intein in the Pyrococcus A-ATPase. Phylogenetic analyses suggest that this intein was horizontally transferred between Pyrococcus and Thermoplasma, and that the small intein has persisted in Thermoplasma apparently without homing

Ethical climate and work performance of nursing professionals in the Covid-19 Villa Panamericana care and isolation center, Villa el Salvador, Peru, 2022

Metodología: Se utilizó con el fin de comprobar la hipótesis, se utilizó el método hipotético deductivo, de enfoque o ruta cuantitativo, el estudio corresponde al alcance o nivel descriptivo correlacional, de tipo aplicada, con diseño no experimental de corte transversal. La población y muestra se encuentra constituida por 98 profesionales de enfermerías entre licenciados y técnicos en enfermería que laboran en el Centro de atención y aislamiento temporal covid19 villa panamericana, que cumplieron los criterios de inclusión y exclusión, a ellos se les aplicó los cuestionarios respectivos para evaluar el clima ético y la satisfacción laboral. Resultados: La prueba de hipótesis indica que el coeficiente de correlación de Rho de Spearman obtenido es 0,490. Conclusiones: Existe relación positiva y según la significancia al p<0.05, nos indica que si es significativa la relación entre clima ético y la satisfacción laboral

Mejora del servicio atención de denuncias al sistema administrativo de gestión de recursos humanos-Servir

En el presente trabajo el grupo se ha enfocado en la Gerencia de Desarrollo del Sistema de Recursos Humanos, que es la unidad orgánica que se encarga de la implementación y supervisión del cumplimiento de las políticas de gestión de los recursos humanos en las entidades del sector público, por lo que es la responsable de atender las denuncias por incumplimiento a dichas políticas. De la información obtenida a partir de los mismos usuarios, se ha evidenciado insatisfacción por la atención en este servicio y considerando el impacto que genera la atención de las denuncias en la gestión de personal de las entidades, este trabajo de investigación busca perfeccionar el servicio y así contribuir a la mejora de la gestión pública, tomando como referencia las experiencias exitosas en otros servicios que brinda SERVIR

Early Cerebral Hemodynamic, Metabolic, and Histological Changes in Hypoxic–Ischemic Fetal Lambs during Postnatal Life

The hemodynamic, metabolic, and biochemical changes produced during the transition from fetal to neonatal life may be aggravated if an episode of asphyxia occurs during fetal life. The aim of the study was to examine regional cerebral blood flow (RCBF), histological changes, and cerebral brain metabolism in preterm lambs, and to analyze the role of oxidative stress in the first hours of postnatal life following severe fetal asphyxia. Eighteen chronically instrumented newborn lambs were randomly assigned to either a control group or the hypoxic–ischemic (HI) group, in which case fetal asphyxia was induced just before delivery. All the animals were maintained on intermittent positive pressure ventilation for 3 h after delivery. During the HI insult, the injured group developed acidosis, hypoxia, hypercapnia, lactic acidosis, and tachycardia (relative to the control group), without hypotension. The intermittent positive pressure ventilation transiently improved gas exchange and cardiovascular parameters. After HI injury and during ventilatory support, there continued to be an increased RCBF in inner regions among the HI group, but no significant differences were detected in cortical flow compared to the control group. Also, the magnitude of the increase in TUNEL positive cells (apoptosis) and antioxidant enzymes, and decrease of ATP reserves was significantly greater in the brain regions where the RCBF was not higher. In conclusion, our findings identify early metabolic, histological, and hemodynamic changes involved in brain damage in premature asphyxiated lambs. Such changes have been described in human neonates, so our model could be useful to test the safety and the effectiveness of different neuroprotective or ventilation strategies applied in the first hours after fetal HI injury

An R2R3 MYB transcription factor determines red petal colour in an Actinidia (kiwifruit) hybrid population

Background Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour. Results Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals. A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia. The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays. Conclusions The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits

Simulation of a coke wastewater nitrification process using a feed-forward neuronal net

A laboratory-scale Activated Sludge System (ASS) was employed for the biodegradation of coke wastewater, which contains high concentrations of ammonium, thiocyanate, phenols and other organic compounds. The well-known kinetics models of Monod or Haldane are not very useful due to inhibition phenomena amongst the pollutants and also, they need the determination of a wide range of parameters to be introduced in the models. In this paper, a feed-forward neural network is outlined to obtain a satisfactory approach for estimating the effluent ammonium concentration of the treatment plan

Research highlights from the 2018 ERS International Congress: interstitial lung diseases

This article reviews a selection of the scientific presentations on interstitial lung disease (ILD)/diffuse parenchymal lung disease (DPLD) that were made at the 2018 European Respiratory Society (ERS) International Congress in Paris. A number of advances in the epidemiology, pathogenesis, diagnosis and treatment of these disorders were presented and discussed by clinicians and researchers. The research topics span over all four groups of ERS Assembly 12: Interstitial Lung Diseases (Group 12.01: Idiopathic interstitial pneumonias; Group 12.02: ILD/DPLD of known origin; Group 12.03: Sarcoidosis and other granulomatous ILD/DPLD; Group 12.04: Rare ILD/DPLD)

Linfoma Burkitt primario de apéndice cecal: Reporte de caso

Introduction: Primary lymphoma of the appendix occurs in 0.015% of all malignant neoplasms of the appendix. The most frequent clinical manifestation is acute appendicitis, and pathological analysis is very important. Case report: Primary lymphoma of the cecal appendix, a 38-year-old man was admitted with acute appendicitis. Macroscopic histopathological study shows diffusely thickened white appendage wall. Microscopically: high-grade Burkitt lymphoma, ACL, CD20, CD10 positive, KI 67 positive 95%, CD3, BCL2, EBV negative. Postoperative: thoracic abdominal tomography showed a tumor in the right iliac fossa without lesions or adenopathies in the abdomen and thorax. The patient was treated with two courses of chemotherapy and a control abdominal CT was performed at 6 months, which showed the initial tumor. At 6 months the patient is stable and controlled. Conclusion: The value of the histopathological study in cecal appendages is emphasized in the presence of primary cecal lymphomas. This case emphasizes the value of the histopathological study in the cecal appendages in the presence of primary cecal lymphomas. Key Words: Primary lymphoma, appendix, Burkitt lymphoma [DeCS/MESH].Introducción: El linfoma primario de apéndice ocurre en 0,015% de todas las neoplasias malignas de apéndice. La manifestación clínica más frecuente es apendicitis aguda y el análisis anatomo patológico es muy importante. Reporte de caso: Linfoma primario de apéndice cecal, varón de 38 años, ingresó con apendicitis aguda. Estudio histopatológico macroscópico muestra pared apendicular difusamente engrosada color blanco. Microscópicamente: linfoma de alto grado Burkitt, ACL, CD20, CD10 positivo, KI 67 positivos 95%, CD3, BCL2, EBV negativo. Post operatorio: tomografía abdomino torácica mostró tumoración de fosa iliaca derecha sin lesiones ni adenopatías en abdomen y tórax.  El paciente fue tratado con dos cursos de quimioterapia y se le realizó TAC abdominal control a los 6 meses, esta evidenció la tumoración inicial. A los 6 meses el paciente se encuentra estable y controlado. Conclusión: Se enfatiza el valor del estudio histopatológico en los apéndices cecales ante la presencia de linfomas cecales primarios. Este caso enfatiza el valor del estudio histopatológico en los apéndices cecales ante la presencia de linfomas cecales primarios Palabras Claves: Linfoma primario, apéndice, linfoma de Burkitt [DeCS/MESH]

Research highlights from the 2018 ERS International Congress: interstitial lung diseases

This article reviews a selection of the scientific presentations on interstitial lung disease (ILD)/diffuse parenchymal lung disease (DPLD) that were made at the 2018 European Respiratory Society (ERS) International Congress in Paris. A number of advances in the epidemiology, pathogenesis, diagnosis and treatment of these disorders were presented and discussed by clinicians and researchers. The research topics span over all four groups of ERS Assembly 12: Interstitial Lung Diseases (Group 12.01: Idiopathic interstitial pneumonias; Group 12.02: ILD/DPLD of known origin; Group 12.03: Sarcoidosis and other granulomatous ILD/DPLD; Group 12.04: Rare ILD/DPLD)