Regeneración de plantas via embriogénesis somática en Phaseolus acutifolius A. Gray

Plant regeneration protocols are a requirement to develop plants transformation systems.The capacity of Phaseolus acutifolius A. Gray to regenerate plants from embryogenic callus formation was investigated. Two explants were used to form calli on a culture medium containing thidiazuron and indole-3-acetic acid. The embryonic axes showed better capacity than cotyledons to form embryos. Solar light was the most favourable to develop the in vitro plants. The 32% of somatic embryos with complete germination was achieved. These results indicate that somatic embryos formation and their germination in Phaseolus acutifolius A. Gray depended on the explant, culture medium and illumination conditions. In vitro-germinated plantlets were established in the greenhouse.Key words: bean, callus formation, plant regeneration, tissue culturePara desarrollar un sistema de transformación genética un requisito fundamental es contar con un protocolo de regeneración de plantas. En el trabajo se investigó la capacidad de Phaseolus acutifolius para regenerar plantas a partir de callos con estructuras embriogénicas. Se utilizaron dos tipos de explantes para la formación de callos en un medio de cultivo que contenía thidiazuron y ácido indol-acético. Los ejes embrionarios mostraron una mejor capacidad que los cotiledones para la formación de embriones somáticos. La luz solar resultó ser la más favorable para el desarrollo de las plantas in vitro. En estas condiciones se alcanzó el 32% de los embriones somáticos con germinación completa. Estos resultados indicanron que la formación de embriones somáticos y su germinación en Phaseolus acutifolius dependieron del explante, el medio de cultivo y las condiciones de iluminación. Las plantas germinadas in vitro, pudieron ser aclimatizadas en el invernadero.Palabras clave: cultivo de tejidos, formación de callos, frijol, regeneración de plantasAbbreviations: BAP 6- Benzylaminopurine, TDZ Thidiazuron, IAA indole-3-acetic acid, GA3 gibberellic acid, AgNO3 silver nitrat

Myosin Sequestration Regulates Sarcomere Function, Cardiomyocyte Energetics, and Metabolism, Informing the Pathogenesis of Hypertrophic Cardiomyopathy

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is caused by pathogenic variants in sarcomere protein genes that evoke hypercontractility, poor relaxation, and increased energy consumption by the heart and increased patient risks for arrhythmias and heart failure. Recent studies show that pathogenic missense variants in myosin, the molecular motor of the sarcomere, are clustered in residues that participate in dynamic conformational states of sarcomere proteins. We hypothesized that these conformations are essential to adapt contractile output for energy conservation and that pathophysiology of HCM results from destabilization of these conformations. METHODS: We assayed myosin ATP binding to define the proportion of myosins in the super relaxed state (SRX) conformation or the disordered relaxed state (DRX) conformation in healthy rodent and human hearts, at baseline and in response to reduced hemodynamic demands of hibernation or pathogenic HCM variants. To determine the relationships between myosin conformations, sarcomere function, and cell biology, we assessed contractility, relaxation, and cardiomyocyte morphology and metabolism, with and without an allosteric modulator of myosin ATPase activity. We then tested whether the positions of myosin variants of unknown clinical significance that were identified in patients with HCM, predicted functional consequences and associations with heart failure and arrhythmias. RESULTS: Myosins undergo physiological shifts between the SRX conformation that maximizes energy conservation and the DRX conformation that enables cross-bridge formation with greater ATP consumption. Systemic hemodynamic requirements, pharmacological modulators of myosin, and pathogenic myosin missense mutations influenced the proportions of these conformations. Hibernation increased the proportion of myosins in the SRX conformation, whereas pathogenic variants destabilized these and increased the proportion of myosins in the DRX conformation, which enhanced cardiomyocyte contractility, but impaired relaxation and evoked hypertrophic remodeling with increased energetic stress. Using structural locations to stratify variants of unknown clinical significance, we showed that the variants that destabilized myosin conformations were associated with higher rates of heart failure and arrhythmias in patients with HCM. CONCLUSIONS: Myosin conformations establish work-energy equipoise that is essential for life-long cellular homeostasis and heart function. Destabilization of myosin energy-conserving states promotes contractile abnormalities, morphological and metabolic remodeling, and adverse clinical outcomes in patients with HCM. Therapeutic restabilization corrects cellular contractile and metabolic phenotypes and may limit these adverse clinical outcomes in patients with HCM

Plant regeneration via somatic embryogenesis in <em>Phaseolus acutifolius</em> A. Gray

Plant regeneration protocols are a requirement to develop plants transformation systems.The capacity of Phaseolus acutifolius A. Gray to regenerate plants from embryogenic callus formation was investigated. Two explants were used to form calli on a culture medium containing thidiazuron and indole-3-acetic acid. The embryonic axes showed better capacity than cotyledons to form embryos. Solar light was the most favourable to develop the in vitro plants. The 32% of somatic embryos with complete germination was achieved. These results indicate that somatic embryos formation and their germination in Phaseolus acutifolius A. Gray depended on the explant, culture medium and illumination conditions. In vitro-germinated plantlets were established in the greenhouse. Key words: bean, callus formation, plant regeneration, tissue cultur