INVESTIGADORES
MORENO Silvia Margarita
artículos
Título:
Threshold level of protein kinase A activity and polarized growth in Mucor rouxii
Autor/es:
PEREYRA ELBA; MIZYRYCKI CYNTHIA; MORENO, SILVIA
Revista:
MICROBIOLOGY-UK
Editorial:
Society General Microbiology
Referencias:
Lugar: Reino Unido; Año: 2000 vol. 146 p. 1949 - 1958
ISSN:
1350-0872
Resumen:
A model system to study the involvement of cAMP-mediated regulation of a
cellular process such as hyphal morphogenesis was investigated. Impairment
of polarized growth was observed when Mucor rouxii sporangiospores were
grown in the presence of N6-cAMP analogues and of SQ 65,442, a cAMP
phosphodiesterase inhibitor. Together with an effect on isodiametric growth,
there was increased pigmentation, increased cell fragility and loss of cell
adhesiveness. The total effect on morphology was attained even after adding
the compounds shortly before germ-tube emergence; when added after this
time growth continued in a non-polarized form and rounding of the germ tip
was observed. The morphological effect was observed under all the nutritional
and environmental conditions studied (aerobic conditions and defined medium
with maltose or glucose, Casamino acids medium with glucose, or rich
medium; anaerobic conditions with rich medium; and following a shift from
anaerobiosis to aerobiosis). The time of germ-tube emergence, and the size of
the cell at this time, was dependent on the growth medium. Protein kinase A
(PKA) specific activity was followed during the germination process under
three growth conditions. It was found that the total activity of PKA correlated
with differentiation and not with growth, and that the total specific activity at
the time of germination was the same, independent of the culture medium.
The time of germ-tube emergence correlated with the time of attainment of a
threshold level of PKA total specific activity. The concentration of dibutyrylcAMP
needed to promote isodiametric growth correlated with the total units
of activity of PKA to be activated per cell. It was concluded that PKA is
involved in the morphogenetic process of the fungus grown under all the
nutritional and ambient conditions tested.Mucor rouxii sporangiospores were
grown in the presence of N6-cAMP analogues and of SQ 65,442, a cAMP
phosphodiesterase inhibitor. Together with an effect on isodiametric growth,
there was increased pigmentation, increased cell fragility and loss of cell
adhesiveness. The total effect on morphology was attained even after adding
the compounds shortly before germ-tube emergence; when added after this
time growth continued in a non-polarized form and rounding of the germ tip
was observed. The morphological effect was observed under all the nutritional
and environmental conditions studied (aerobic conditions and defined medium
with maltose or glucose, Casamino acids medium with glucose, or rich
medium; anaerobic conditions with rich medium; and following a shift from
anaerobiosis to aerobiosis). The time of germ-tube emergence, and the size of
the cell at this time, was dependent on the growth medium. Protein kinase A
(PKA) specific activity was followed during the germination process under
three growth conditions. It was found that the total activity of PKA correlated
with differentiation and not with growth, and that the total specific activity at
the time of germination was the same, independent of the culture medium.
The time of germ-tube emergence correlated with the time of attainment of a
threshold level of PKA total specific activity. The concentration of dibutyrylcAMP
needed to promote isodiametric growth correlated with the total units
of activity of PKA to be activated per cell. It was concluded that PKA is
involved in the morphogenetic process of the fungus grown under all the
nutritional and ambient conditions tested.N6-cAMP analogues and of SQ 65,442, a cAMP
phosphodiesterase inhibitor. Together with an effect on isodiametric growth,
there was increased pigmentation, increased cell fragility and loss of cell
adhesiveness. The total effect on morphology was attained even after adding
the compounds shortly before germ-tube emergence; when added after this
time growth continued in a non-polarized form and rounding of the germ tip
was observed. The morphological effect was observed under all the nutritional
and environmental conditions studied (aerobic conditions and defined medium
with maltose or glucose, Casamino acids medium with glucose, or rich
medium; anaerobic conditions with rich medium; and following a shift from
anaerobiosis to aerobiosis). The time of germ-tube emergence, and the size of
the cell at this time, was dependent on the growth medium. Protein kinase A
(PKA) specific activity was followed during the germination process under
three growth conditions. It was found that the total activity of PKA correlated
with differentiation and not with growth, and that the total specific activity at
the time of germination was the same, independent of the culture medium.
The time of germ-tube emergence correlated with the time of attainment of a
threshold level of PKA total specific activity. The concentration of dibutyrylcAMP
needed to promote isodiametric growth correlated with the total units
of activity of PKA to be activated per cell. It was concluded that PKA is
involved in the morphogenetic process of the fungus grown under all the
nutritional and ambient conditions tested.