ABSTRACT
Under optimal conditions of growth, senescence, a terminal phase of development, sets in after a certain physiological age. It is a dynamic and closely regulated developmental process which involves an array of changes at both physiological and biochemical levels including gene expression. A large number of biotic and abiotic factors accelerate the process. Convincing evidence suggests the involvement of polyamines (PAs) and ethylene in this process. Although the biosynthetic pathways of both PAs and ethylene are interrelated, S-adenosylmethionine (SAM) being a common precursor, their physiological functions are distinct and at times antagonistic, particularly during leaf and flower senescence and also during fruit ripening. This provides an effective means for regulation of their biosynthesis and also to understand the mechanism by which the balance between the two can be established for manipulating the senescence process. The present article deals with current advances in the knowledge of the interrelationship between ethylene and PAs during senescence which may open up new vistas of investigation for the future.
Subject(s)
Adenosylmethionine Decarboxylase/physiology , Arginine/metabolism , Cellular Senescence , Ethylenes/metabolism , Gene Expression Regulation, Plant , Homeostasis , Methionine/metabolism , Models, Biological , Ornithine Decarboxylase/physiology , Plant Growth Regulators/physiology , Plant Physiological Phenomena , Plant Proteins/physiology , Plants/growth & development , Polyamines/metabolism , S-Adenosylmethionine/physiologyABSTRACT
El autor destaca la importancia de la experiencia táctil como estímulo del desarrollo y la adaptación social del ser humano, a partir de la vida intrauterina. Subraya la influencia del contacto con otro ser humano y diferencia sus afectos positivos o negativos en función de la sensibilidad del niño en etapas muy tempranas