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Branching in filamentous fungi appears to occur when the synthesis and transport of tip-growth vesicles exceeds the deposition of the vesicles at the apex. Branching is independent of temperature and tip growth rate.

An analysis of prototypes of plasmid suppressor and their activity in the sexual cycle of Neurospora intermedia reveals that plasmid suppression depends on strain-specific interaction rather than exclusively relying on the presence of male strains. Transmission and non-transmission of plasmids in female parent strains correspond to the type of male parent strain used in the test crosses. Segregation of suppressed and expressed phenotypes in octads facilitates a substantial test for the genetic basis of suppression phenomenon.

Maternal and paternal legacies in mitochondrial genetic elements in the Neurospora fungus were studied to understand the patterns of uniparental inheritance. Anisogamous matings in organelles involve the transmission of genetic characteristics from the maternal side, with a few cases of transmission from the paternal side. Two new cases of parental transmission in Neurospora, with transmission frequencies between 1% to 15%, were discovered.

Actin has a pivotal function in hyphal morphogenesis in filamentous fungi, but it is not certain whether its function is equivalent to that of a morphogen, or if it is simply part of a mechanism that executes orders given by another regulatory entity. To address this question we selected for cytochalasin A resistance and isolated act1, the first actin mutant in Neurospora crassa. This mutant branches apically and shows an altered distribution of actin at the tip. Based on the properties of this mutant, we propose a model of tip growth and branching in which actin effects tip growth by regulating the rate of vesicle flow from proximal to distal regions of a hypha, thereby controlling the tip-high gradient of cytoplasmic calcium. The actin-controlled calcium gradient at the tip is necessary for maintenance of tip growth as well as the dominance of one polarized site at the hyphal tip. The phenotype of act1 indicates that actin controls the balance between lateral and apical branching. [Copyright &y& Elsevier]

Reports on the presence of plasmid suppressors in natural populations of the fungi Neurospora intermedia. Testcrosses of progeny of cross 1940; Dependence of plasmid suppression on a strain-specific interaction; Segregation of original full suppression of all plasmids; Interaction type of suppression in ascogenous tissue in one sexual cycle.

Reports two cases of paternal transmission of genetic elements of organelles in crosses of the fungus Neuspora. General rule in anisogamous matings; Linear plasmids; Mitochondrial deoxyribonucleic acid (DNA); Heteroplasmons; Mitochondrial segregation and assortment; Associations between genomic compartments and between genomic and extragenomic elements.

Discusses molecular processes in senescence of three fungi. Podospora anserine; Aspergillus amstelodami; Neurospora species; Senescence phenotype; Inheritance; Chemical and genetic modification; Strains.