RESUMEN
Plant roots can regenerate after excision of their tip, including the stem cell niche. To determine which developmental program mediates such repair, we applied a combination of lineage tracing, single-cell RNA sequencing, and marker analysis to test different models of tissue reassembly. We show that multiple cell types can reconstitute stem cells, demonstrating the latent potential of untreated plant cells. The transcriptome of regenerating cells prior to stem cell activation resembles that of an embryonic root progenitor. Regeneration defects are more severe in embryonic than in adult root mutants. Furthermore, the signaling domains of the hormones auxin and cytokinin mirror their embryonic dynamics and manipulation of both hormones alters the position of new tissues and stem cell niche markers. Our findings suggest that plant root regeneration follows, on a larger scale, the developmental stages of embryonic patterning and is guided by spatial information provided by complementary hormone domains.
Asunto(s)
Raíces de Plantas/fisiología , Citocininas/metabolismo , Perfilación de la Expresión Génica , Ácidos Indolacéticos/metabolismo , Células Vegetales , Reguladores del Crecimiento de las Plantas/metabolismo , Raíces de Plantas/citología , Semillas , Análisis de la Célula Individual , Nicho de Células Madre , Células Madre/citologíaRESUMEN
The diversity (richness and community composition) of ammonia-oxidizing archaea (AOA) and bacteria (AOB) within sediments of the Gulf of Mexico was examined. Using polymerase chain reaction primers designed to specifically target the archaeal ammonia monooxygenase-subunit (amoA) gene and bacterial amoA gene, we found AOA and AOB to be present in all three sampling sites. Archaeal amoA libraries were dominated by a few widely distributed Nitrosopumilus-like sequence types, whereas AOB diversity showed significant variation in both richness and community composition. Majority of the bacterial amoA sequences recovered belong to Betaproteobacteria and very few belong to Gammaproteobacteria. Results suggest that water depth and nutrient availability were identified as potential drivers that affected the selection of the AOA and AOB communities. Besides influencing the abundance of individual taxa, these environmental factors also had an impact on the overall richness of the overall AOA and AOB communities. The richness and diversity of AOA and AOB genes were higher at the shallowest sediments (100 m depth) and the deepest sediments (1300 m depth). The reduced diversity in the deepest sediments could be explained by much lower nutrient availability.
Asunto(s)
Amoníaco/metabolismo , Archaea/fisiología , Bacterias/aislamiento & purificación , Fenómenos Fisiológicos Bacterianos , Sedimentos Geológicos/microbiología , Agua de Mar/microbiología , Archaea/clasificación , Archaea/aislamiento & purificación , Bacterias/clasificación , Golfo de México , Oxidación-Reducción , Especificidad de la EspecieRESUMEN
Cell-cycle fluctuations drive significant transcriptomic heterogeneity in murine hematopoietic stem cells. Additionally, deletion of Bcl11a alters the regulation of hematopoietic stem cell quiescence, self-renewal, and fate choice.
Asunto(s)
Proteínas Portadoras/genética , Diferenciación Celular/genética , Células Madre Hematopoyéticas/metabolismo , Proteínas Nucleares/genética , Análisis de la Célula Individual , Animales , Linaje de la Célula/genética , Proteínas de Unión al ADN , Células Madre Hematopoyéticas/citología , Secuenciación de Nucleótidos de Alto Rendimiento , Ratones , Proteínas Represoras , Transducción de Señal , Trombopoyesis/genéticaRESUMEN
PURPOSE: To describe the clinical and contextual factors that influence physiotherapists' discharge decision-making processes in outpatient orthopaedic settings. METHODS: The study used a descriptive qualitative design that included three key-informant interviews and two focus groups (n=7) of orthopaedic physiotherapists (total n=10) working in the Greater Toronto Area. Interviews and focus groups followed a semi-structured interview guide that included questions pertaining to participants' discharge decision-making processes, salient contextual factors, and challenges. Data were coded and analyzed for emerging categories and themes using constant comparison techniques and group analyses. RESULTS: Participants indicated that a combination of factors and strategies were brought to bear on discharge decision making but that the process changed with clinical experience. Over time, further emphasis was attributed to the patient's role in his or her rehabilitation, and self-management goals were increasingly promoted. Experience affected how therapists conceptualized their roles in discharge decisions and how they negotiated goals with patients. CONCLUSIONS: Discharge decision making is a complex process that requires integrating numerous factors and negotiating with patients. Physiotherapists' decision-making practices evolve with experience and reveal the complexity of implementing models of "client-centred care" in practice. Further research is needed to explore these findings in other settings.