Faculty Opinions recommendation of A mutation in the Neurospora crassa actin gene results in multiple defects in tip growth and branching.

Growing hyphae of the ascomycete fungus Neurospora crassa contained a tip-high gradient of cytoplasmic Ca2+, which was absent in non-growing hyphae and was insensitive to Gd3+ in the medium. Patch clamp recordings in the cell-attached mode, from the plasma membrane of these hyphae, showed two types of channel activities; spontaneous and stretch activated. The spontaneous channels were identified as inward K+ channels based on inhibition by tetraethylammonium. The stretch activated channels had increased amplitudes in response to elevated Ca2+ in the pipette solution, and thus are permeable to Ca2+ and mediate inward Ca2+ movement. Gd3+, which is an inhibitor of some stretch activated channels, incompletely inhibited stretch activated channel activity. Both tetraethylammonium and Gd3+ only transiently reduced the rates of tip growth without changing tip morphology, thus indicating that the channels are not absolutely essential for tip growth. Furthermore, in contrast to the hyphae of another tip growing organism, Saprolegnia ferax, tip-high gradients of neither spontaneous nor stretch activated channels were found. Voltage clamping of the apical plasma membrane potential in the range from -300 to +150 mV did not affect the rates of hyphal elongation. Collectively, these data suggest that ion transport across the plasma membrane at the growing tip in Neurospora is not obligatory for the maintenance of tip growth, but that a gradient of Ca2+, possibly generated from internal stores in an unknown way, is required.

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Problem of interactions between intracellular structures during the Neurospora crassa tip growth

Doklady Biochemistry and Biophysics ◽

10.1134/s1607672911010145 ◽

2011 ◽

Vol 436 (1) ◽

pp. 44-48 ◽

Cited By ~ 2

Author(s):

T. V. Potapova ◽

L. Yu. Boitzova ◽

S. A. Golyshev

Keyword(s):

Neurospora Crassa ◽

Tip Growth

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Tests of a Cellular Model for Constant Branch Distribution in the Filamentous Fungus Neurospora crassa

Applied and Environmental Microbiology ◽

10.1128/aem.67.4.1788-1792.2001 ◽

2001 ◽

Vol 67 (4) ◽

pp. 1788-1792 ◽

Cited By ~ 24

Author(s):

Michael K. Watters ◽

Anthony J. F. Griffiths

Keyword(s):

Growth Rate ◽

Neurospora Crassa ◽

Tip Growth ◽

Extension Rate ◽

Mycelial Fungi ◽

Organic Substrates ◽

Cellular Model ◽

Wild Type ◽

Tip Extension ◽

Pass Through

ABSTRACT The growth of mycelial fungi is characterized by the highly polarized extension of hyphal tips and the formation of subapical branches, which themselves extend as new tips. In Neurospora crassa, tip growth and branching are crucial elements for this saprophyte in the colonization and utilization of organic substrates. Much research has focused on the mechanism of tip extension, but a cellular model that fully explains the known phenomenology of branching by N. crassa has not been proposed. We described and tested a model in which the formation of a lateral branch in N. crassa was determined by the accumulation of tip-growth vesicles caused by the excess of the rate of supply over the rate of deposition at the apex. If both rates are proportional to metabolic rate, then the model explains the known lack of dependence of branch interval on growth rate. We tested the model by manipulating the tip extension rate, first by shifting temperature in both the wild type and hyperbranching (colonial) mutants and also by observing the behavior of both tipless colonies and colonyless tips. We found that temperature shifts in either direction result in temporary changes in branching. We found that colonyless tips also pass through a temporary transition phase of branching. The tipless colonies produced a cluster of new tips near the point of damage. We also found that branching in colonial mutants is dependent on growth rate. The results of these tests are consistent with a model of branching in which branch initiation is controlled by the dynamics of tip growth while being independent of the actual rate of this growth.

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Tip growth of Neurospora crassa under glucose deprivation

Biochemistry (Moscow) Supplement Series A Membrane and Cell Biology ◽

10.1134/s1990747808030033 ◽

2008 ◽

Vol 2 (3) ◽

pp. 210-216

Author(s):

T. V. Potapova ◽

T. A. Alekseevskii ◽

L. Yu. Boitzova

Keyword(s):

Neurospora Crassa ◽

Tip Growth ◽

Glucose Deprivation

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