RESUMO
The production of unisexual flowers has evolved numerous times in dioecious and monoecious plant taxa. Based on repeated evolutionary origins, a great variety of developmental and genetic mechanisms underlying unisexual flower development is predicted. Here, we comprehensively review the modes of development of unisexual flowers, test potential correlations with sexual system, and end with a synthesis of the genetics and hormonal regulation of plant sex determination. We find that the stage of organ abortion in male and female flowers is temporally correlated within species and also confirm that the arrest of development does not tend to occur preferentially at a particular stage, or via a common process.
Assuntos
Cromossomos de Plantas , Magnoliopsida/crescimento & desenvolvimento , Evolução Molecular , Flores/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Magnoliopsida/genética , Morfogênese/genética , Fenótipo , Reguladores de Crescimento de Plantas/genética , Reprodução/genéticaRESUMO
Peptidylarginine deiminases (PADIs) are strongly associated with the development of autoimmunity, neurodegeneration and cancer but their physiological roles are ill-defined. The nuclear deiminase PADI4 regulates pluripotency in the mammalian pre-implantation embryo but its function in tissue development is unknown. PADI4 is primarily expressed in the bone marrow, as part of a self-renewal-associated gene signature. It has been shown to regulate the proliferation of multipotent haematopoietic progenitors and proposed to impact on the differentiation of haematopoietic stem cells (HSCs), suggesting that it controls haematopoietic development or regeneration. Using conditional in vivo models of steady state and acute Padi4 ablation, we examined the role of PADI4 in the development and function of the haematopoietic system. We found that PADI4 loss does not significantly affect HSC self-renewal or differentiation potential upon injury or serial transplantation, nor does it lead to HSC exhaustion or premature ageing. Thus PADI4 is dispensable for cell-autonomous HSC maintenance, differentiation and haematopoietic regeneration. This work represents the first study of PADI4 in tissue development and indicates that pharmacological PADI4 inhibition may be tolerated without adverse effects.
Assuntos
Hidrolases , Mamíferos , Animais , Diferenciação Celular/genética , Hidrolases/genética , Proteína-Arginina Desiminase do Tipo 4 , Desiminases de Arginina em Proteínas/genéticaRESUMO
Paradoxical vocal cord movement (PVCM) causes inspiratory stridor and extra-thoracic airway obstruction through inappropriate adduction of the vocal cords during the respiratory cycle. We report on a patient with severe PVCM necessitating tracheostomy insertion. Using the technique of endoscopic suture lateralization of a vocal cord, we succeeded in decannulation 22 years after tracheostomy. PVCM of this severity is rare and its management remains unclear. Successful treatment in this manner has not been documented previously. A brief review of current management options for this condition is included.