Marginality in Inquiry-Based Science Learning Contexts: The Role of Exclusion Cascades

Vygotskyan-inspired theories of learning have been applied in science education research, yet to more explicit attention to links between local social interactions and cultural-historical processes is needed advance critical theories of science learning. This microgenetic case study examined identity and motivation processes in a 7th grade inquiry science context with the goal of better historicizing these processes by describing the phenomenon of exclusion cascades in relation to two backgrounded cultural-historical processes, alienation and the social division of labor. Exclusion cascades highlighted the mutual constitution of competence and belonging. Implications are discussed with respect to challenging adaptationist ethos in science education

The evolution of core proteins involved in microRNA biogenesis

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are a recently discovered class of non-coding RNAs (ncRNAs) which play important roles in eukaryotic gene regulation. miRNA biogenesis and activation is a complex process involving multiple protein catalysts and involves the large macromolecular RNAi Silencing Complex or RISC. While phylogenetic analyses of miRNA genes have been previously published, the evolution of miRNA biogenesis itself has been little studied. In order to better understand the origin of miRNA processing in animals and plants, we determined the phyletic occurrences and evolutionary relationships of four major miRNA pathway protein components; Dicer, Argonaute, RISC RNA-binding proteins, and Exportin-5.</p> <p>Results</p> <p>Phylogenetic analyses show that all four miRNA pathway proteins were derived from large multiple protein families. As an example, vertebrate and invertebrate Argonaute (Ago) proteins diverged from a larger family of PIWI/Argonaute proteins found throughout eukaryotes. Further gene duplications among vertebrates after the evolution of chordates from urochordates but prior to the emergence of fishes lead to the evolution of four Ago paralogues. Invertebrate RISC RNA-binding proteins R2D2 and Loquacious are related to other RNA-binding protein families such as Staufens as well as vertebrate-specific TAR (HIV trans-activator RNA) RNA-binding protein (TRBP) and protein kinase R-activating protein (PACT). Export of small RNAs from the nucleus, including miRNA, is facilitated by three closely related karyopherin-related nuclear transporters, Exportin-5, Exportin-1 and Exportin-T. While all three exportins have direct orthologues in deutrostomes, missing exportins in arthropods (Exportin-T) and nematodes (Exportin-5) are likely compensated by dual specificities of one of the other exportin paralogues.</p> <p>Conclusion</p> <p>Co-opting particular isoforms from large, diverse protein families seems to be a common theme in the evolution of miRNA biogenesis. Human miRNA biogenesis proteins have direct, orthologues in cold-blooded fishes and, in some cases, urochordates and deutrostomes. However, lineage specific expansions of Dicer in plants and invertebrates as well as Argonaute and RNA-binding proteins in vertebrates suggests that novel ncRNA regulatory mechanisms can evolve in relatively short evolutionary timeframes. The occurrence of multiple homologues to RNA-binding and Argonaute/PIWI proteins also suggests the possible existence of further pathways for additional types of ncRNAs.</p

Factores de riesgos asociados a lesiones por presión en pacientes del servicio de medicina, Hospital Daniel Alcides Carrión, Callao- 2023

La presente investigación tuvo por objetivo “Determinar los factores de riesgo asociados a la presencia de lesiones por presión en el Hospital Daniel Alcides Carrión". Callao, 2023; el método: fue básica, no experimental, transversal, correlacional, enfoque cuantitativo; población: 350 historias clínicas; muestra: 120 historia clínicas, muestreo probabilístico, aleatorizado; unidad de análisis: historia clínica; técnica: revisión documentaria, el instrumento: ficha de recolección de datos; la validación: juicio de expertos; confiabilidad Alfa de Cronbach de 0,78; en los resultados se encontraron: dentro de los factores intrínsecos: la edad con 22% (p=0,000); la hipoproteinemia con 7% (p = 0,041), la anemia, con 11% de casos ( p = 0,011) son factores de riesgo asociados a lesión por presión. En los factores extrínsecos: la hospitalización mayor de 48 horas, con 18% (p = 0,001); la postración con 10% (p = 0,046); el menor cambio de frecuencia postural con 11% (p = 0,011), el 3% donde se descuidaron las acciones de enfermería sobre cuidados de la piel (p= 0,016) son factores de riesgo asociados a lesión por presión; por tanto, concluimos: en los factores intrínsecos, tener una edad mayor de 60 años, padecer de hipoproteinemia, hipoalbuminemia y padecer de anemia son factores de riesgo asociados a lesión por presión; en los factores extrínsecos, la hospitalización de 48 horas a más, la postración, la menor frecuencia de cambio postural y el descuido en acciones de enfermería sobre cuidados de la piel son los factores vinculados a la aparición de lesiones por presión

Trafficking of Siderophore Transporters in Saccharomyces cerevisiae and Intracellular Fate of Ferrioxamine B Conjugates

We have studied the intracellular trafficking of Sit1 [ferrioxamine B (FOB) transporter] and Enb1 (enterobactin transporter) in Saccharomyces cerevisiae using green fluorescent protein (GFP) fusion proteins. Enb1 was constitutively targeted to the plasma membrane. Sit1 was essentially targeted to the vacuolar degradation pathway when synthesized in the absence of substrate. Massive plasma membrane sorting of Sit1 was induced by various siderophore substrates of Sit1, and by coprogen, which is not a substrate of Sit1. Thus, different siderophore transporters use different regulated trafficking processes. We also studied the fate of Sit1-mediated internalized siderophores. Ferrioxamine B was recovered in isolated vacuolar fractions, where it could be detected spectrophotometrically. Ferrioxamine B coupled to an inhibitor of mitochondrial protoporphyrinogen oxidase (acifluorfen) could not reach its target unless the cells were disrupted, confirming the tight compartmentalization of siderophores within cells. Ferrioxamine B coupled to a fluorescent moiety, FOB-nitrobenz-2-oxa-1,3-diazole, used as a Sit1-dependent iron source, accumulated in the vacuolar lumen even in mutants displaying a steady-state accumulation of Sit1 at the plasma membrane or in endosomal compartments. Thus, the fates of siderophore transporters and siderophores diverge early in the trafficking process

Dysautonomia, A Heuristic Approach to a Revised Model for Etiology of Disease

Dysautonomia refers to a disease where the autonomic nervous system is dysfunctional. This may be a central control mechanism, as in genetically determined familial dysautonomia (Riley-Day Syndrome), or peripherally in the distribution of the sympathetic and parasympathetic systems. There are multiple reports of a number of different diseases associated with dysautonomia. The etiology of this association has never been explained. There are also multiple publications on dysautonomia associated with specific non-caloric nutritional deficiencies. Beriberi is the prototype of autonomic dysfunction. It is the best known nutritional deficiency disease caused by an imbalance between ingested calories and the vitamins required for their oxidation, particularly thiamin. Long thought to be abolished in modern medical thinking, there are occasional isolated reports of the full-blown disease in developed Western cultures