32 research outputs found
Лингвистическая модель времени в представлении носителей неблизкородственных языков
В статье рассматривается возможность существования единой темпоральной модели, свойственной неблизкородственным европейским языкам. Представления о пространстве и времени следует считать синкретичными.У статті розглядається можливість існування у неблизькоспоріднених європейських мовах єдиної темпоральної моделі. Уявлення про час і простір слід вважати синкретичними.The article deals with the problem of the universal temporal model that exists in European languages. The main idea is that time and distance are visualized as syncretic notions
Computational universality of fungal sandpile automata
Hyphae within the mycelia of the ascomycetous fungi are compartmentalised by
septa. Each septum has a pore that allows for inter-compartmental and
inter-hyphal streaming of cytosol and even organelles. The compartments,
however, have special organelles, Woronin bodies, that can plug the pores. When
the pores are blocked, no flow of cytoplasm takes place. Inspired by the
controllable compartmentalisation within the mycelium of the ascomycetous fungi
we designed two-dimensional fungal automata. A fungal automaton is a cellular
automaton where communication between neighbouring cells can be blocked on
demand. We demonstrate computational universality of the fungal automata by
implementing sandpile cellular automata circuits there. We reduce the Monotone
Circuit Value Problem to the Fungal Automaton Prediction Problem. We construct
families of wires, cross-overs and gates to prove that the fungal automata are
P-complete
Fungal Automata
We study a cellular automaton (CA) model of information dynamics on a single
hypha of a fungal mycelium. Such a filament is divided in compartments (here
also called cells) by septa. These septa are invaginations of the cell wall and
their pores allow for flow of cytoplasm between compartments and hyphae. The
septal pores of the fungal phylum of the Ascomycota can be closed by organelles
called Woronin bodies. Septal closure is increased when the septa become older
and when exposed to stress conditions. Thus, Woronin bodies act as
informational flow valves. The one dimensional fungal automata is a binary
state ternary neighbourhood CA, where every compartment follows one of the
elementary cellular automata (ECA) rules if its pores are open and either
remains in state `0' (first species of fungal automata) or its previous state
(second species of fungal automata) if its pores are closed. The Woronin bodies
closing the pores are also governed by ECA rules. We analyse a structure of the
composition space of cell-state transition and pore-state transitions rules,
complexity of fungal automata with just few Woronin bodies, and exemplify
several important local events in the automaton dynamics
Attachment of Streptomyces coelicolor is mediated by amyloidal fimbriae that are anchored to the cell surface via cellulose
P>The chaplin proteins ChpA-H enable the filamentous bacterium Streptomyces coelicolor to form reproductive aerial structures by assembling into surface-active amyloid-like fibrils. We here demonstrate that chaplins also mediate attachment of S. coelicolor to surfaces. Attachment coincides with the formation of fimbriae, which are connected to the cell surface via spike-shaped protrusions. Mass spectrometry, electron microscopy and Congo red treatment showed that these fimbriae are composed of bundled amyloid fibrils of chaplins. Attachment and fimbriae formation were abolished in a strain in which the chaplin genes chpA-H were inactivated. Instead, very thin fibrils emerged from the spike-shaped protrusions in this mutant. These fibrils were susceptible to cellulase treatment. This enzymatic treatment also released wild-type fimbriae from the cell surface, thereby abolishing attachment. The reduced attachment of a strain in which the gene of a predicted cellulose synthase was inactivated also indicates a role of cellulose in surface attachment. We propose that the mechanism of attachment via cellulose-anchored amyloidal fimbriae is widespread in bacteria and may function in initiation of infection and in formation of biofilms
A broader role for AmyR in Aspergillus niger: regulation of the utilisation of d-glucose or d-galactose containing oligo- and polysaccharides
AmyR is commonly considered a regulator of starch degradation whose activity is induced by the presence of maltose, the disaccharide building block of starch. In this study, we demonstrate that the role of AmyR extends beyond starch degradation. Enzyme activity assays, genes expression analysis and growth profiling on d-glucose- and d-galactose-containing oligo- and polysaccharides showed that AmyR regulates the expression of some of the Aspergillus niger genes encoding alpha- and beta-glucosidases, alpha- and beta- galactosidases, as well as genes encoding alpha-amlyases and glucoamylases. In addition, we provide evidence that d-glucose or a metabolic product thereof may be the inducer of the AmyR system in A. niger and not maltose, as is commonly assumed
Key Role of Mfd in the Development of Fluoroquinolone Resistance in Campylobacter jejuni
Campylobacter jejuni is a major food-borne pathogen and a common causative agent of human enterocolitis. Fluoroquinolones are a key class of antibiotics prescribed for clinical treatment of enteric infections including campylobacteriosis, but fluoroquinolone-resistant Campylobacter readily emerges under the antibiotic selection pressure. To understand the mechanisms involved in the development of fluoroquinolone-resistant Campylobacter, we compared the gene expression profiles of C. jejuni in the presence and absence of ciprofloxacin using DNA microarray. Our analysis revealed that multiple genes showed significant changes in expression in the presence of a suprainhibitory concentration of ciprofloxacin. Most importantly, ciprofloxacin induced the expression of mfd, which encodes a transcription-repair coupling factor involved in strand-specific DNA repair. Mutation of the mfd gene resulted in an approximately 100-fold reduction in the rate of spontaneous mutation to ciprofloxacin resistance, while overexpression of mfd elevated the mutation frequency. In addition, loss of mfd in C. jejuni significantly reduced the development of fluoroquinolone-resistant Campylobacter in culture media or chickens treated with fluoroquinolones. These findings indicate that Mfd is important for the development of fluoroquinolone resistance in Campylobacter, reveal a previously unrecognized function of Mfd in promoting mutation frequencies, and identify a potential molecular target for reducing the emergence of fluoroquinolone-resistant Campylobacter
Genome sequencing and analysis of the versatile cell factory Aspergillus niger CBS 513.88
The filamentous fungus Aspergillus niger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of the 14,165 open reading frames identified. A detailed description of the components of the protein secretion pathway was made and striking differences in the hydrolytic enzyme spectra of aspergilli were observed. A reconstructed metabolic network comprising 1,069 unique reactions illustrates the versatile metabolism of A. niger. Noteworthy is the large number of major facilitator superfamily transporters and fungal zinc binuclear cluster transcription factors, and the presence of putative gene clusters for fumonisin and ochratoxin A synthesis