Gene expression in<i>Mucor</i>dimorphism

Orlowski, Michael

doi:10.1139/b95-263

Cited by 9 publications

(4 citation statements)

References 63 publications

(59 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As described in the introduction, polyamines affect many proteins in signal transduction pathways (Wright and Boyle, 1982; Bueb et al ., 1991; 1992; Orlowski, 1995; Choi et al ., 1997; Kubota et al ., 1997; Leroy et al ., 1997), including G α proteins. Although we did not test activity of signalling proteins or concentration of second messengers in our study, the results presented in this communication indicate that a relationship exists between G protein signalling control and polyamine control of sporulation and ST biosynthesis.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Requirement of spermidine for developmental transitions in Aspergillus nidulans

Jin

Bok

Guzmán-de-Peña

et al. 2002

Molecular Microbiology

View full text Add to dashboard Cite

SummaryDeletion of the spermidine synthase gene in the fungus Aspergillus nidulans results in a strain, ∆ ∆ ∆ ∆ spdA , which requires spermidine for growth and accumulates putrescine as the sole polyamine. Vegetative growth but not sporulation or sterigmatocystin production is observed when ∆ ∆ ∆ ∆ spdA is grown on media supplemented with 0.05-0.10 mM exogenous spermidine. Supplementation of ∆ ∆ ∆ ∆ spdA with ≥ ≥ ≥ ≥ 0.10 mM spermidine restores sterigmatocystin production and ≥ ≥ ≥ ≥ 0.50 mM spermidine produces a phenotype with denser asexual spore production and decreased radial hyphal growth compared with the wild type. ∆ ∆ ∆ ∆ spdA spores germinate in unsupplemented media but germ tube growth ceases after 8 h upon which time the spores swell to approximately three times their normal diameter. Hyphal growth is resumed upon addition of 1.0 mM spermidine. Suppression of a G protein signalling pathway could not force asexual sporulation and sterigmatocystin production in ∆ ∆ ∆ ∆ spdA strains grown in media lacking spermidine but could force both processes in ∆ ∆ ∆ ∆ spdA strains supplemented with 0.05 mM spermidine. These results show that increasing levels of spermidine are required for the transitions from (i) germ tube to hyphal growth and (ii) hyphal growth to tissue differentiation and secondary metabolism. Suppression of G protein signalling can over-ride the spermidine requirement for the latter but not the former transition.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Furthermore, polyamines have been implicated in depressing cAMP synthesis in bacteria ( Escherichia coli ; Wright and Boyle, 1982) and fungi ( Magnaporthe grisea and Mucor spp. ; Orlowski, 1995; Choi et al ., 1997).…”

Section: Introductionmentioning

confidence: 99%

Requirement of spermidine for developmental transitions in Aspergillus nidulans

Jin

Bok

Guzmán-de-Peña

et al. 2002

Molecular Microbiology

View full text Add to dashboard Cite

show abstract

“…a & Nickerson, 1962). The possible role of cAMP in the morphogenetic process of Mucor has previously attracted the attention of a number of researchers (Orlowski, 1991(Orlowski, , 1995. We have reported that in the presence of dibutyryl-cAMP (dbut-cAMP) the sporangiospores from M. rouxii grow isodiametrically and that polarized growth is prevented without alteration of growth parameters (Pereyra et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Threshold level of protein kinase A activity and polarized growth in Mucor rouxii

2000

View full text Add to dashboard Cite

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 N 6 -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.

show abstract

“…1). The genetic basis and external factors that trigger such transitions in fungal growth forms are currently under intensive investigation in so-called dimorphic fungi among non-lichenized taxa; these switch back and forth between the yeast form with apolar/globose growth and the hyphal form with polar/filamentous growth (Gow et al 1995;Orlowski 1995). The differentiation of both growth types, polar and apolar, in close vicinity, but within functionally completely different thalline areas, as observed in lichen thalli, is a developmental process of distinctly higher complexity than the yeast to hypha transitions of dimorphic fungi.…”

Section: Mutualistic Symbiosesmentioning

confidence: 99%

The Lichen Symbiosis—What is so Spectacular about it?

Honegger

1998

The Lichenologist

View full text Add to dashboard Cite

Lichen mycobionts are typical representatives of their fungal classes but differ from non-lichenized taxa by their manifold adaptations to symbiosis with a population of minute photobiont cells. Most interesting are the morphologically complex macrolichens, the fungal partner of which competes for space above ground and contains photobiont cells optimally positioned for gas exchange and illumination. Such thalli are the product of an amazing hyphal polymorphism, with multiple switches between polar and apolar growth and hydrophilic or hydrophobic cell wall surfaces. Hydrophobic sealing of the apoplastic continuum between the partners by means of mycobiont-derived hydrophobic compounds canalizes the fluxes of solutes during the often quite dramatic de- and rehydration processes and keeps the algal layer gas-filled at any level of hydration. The impressive tolerance of drought, heat and cold stress of most lichen-forming fungi and their photobionts is due to a very interesting combination of protective and repair mechanisms at the cellular level, the molecular bases of which remain to be explored. Contemporary experimental lichenology is analysed and strategies are proposed aimed at better integration into mainstream biology.

show abstract

Gene expression inMucordimorphism

Cited by 9 publications

References 63 publications

Requirement of spermidine for developmental transitions in Aspergillus nidulans

Requirement of spermidine for developmental transitions in Aspergillus nidulans

Threshold level of protein kinase A activity and polarized growth in Mucor rouxii

The Lichen Symbiosis—What is so Spectacular about it?

Contact Info

Product

Resources

About