Is Bacterial Persistence a Social Trait?

The ability of bacteria to evolve resistance to antibiotics has been much reported in recent years. It is less well-known that within populations of bacteria there are cells which are resistant due to a non-inherited phenotypic switch to a slow-growing state. Although such ‘persister’ cells are receiving increasing attention, the evolutionary forces involved have been relatively ignored. Persistence has a direct benefit to cells because it allows survival during catastrophes–a form of bet-hedging. However, persistence can also provide an indirect benefit to other individuals, because the reduced growth rate can reduce competition for limiting resources. This raises the possibility that persistence is a social trait, which can be influenced by kin selection. We develop a theoretical model to investigate the social consequences of persistence. We predict that selection for persistence is increased when: (a) cells are related (e.g. a single, clonal lineage); and (b) resources are scarce. Our model allows us to predict how the level of persistence should vary with time, across populations, in response to intervention strategies and the level of competition. More generally, our results clarify the links between persistence and other bet-hedging or social behaviours

Phenotypic Landscape of Saccharomyces cerevisiae during Wine Fermentation: Evidence for Origin-Dependent Metabolic Traits

The species Saccharomyces cerevisiae includes natural strains, clinical isolates, and a large number of strains used in human activities. The aim of this work was to investigate how the adaptation to a broad range of ecological niches may have selectively shaped the yeast metabolic network to generate specific phenotypes. Using 72 S. cerevisiae strains collected from various sources, we provide, for the first time, a population-scale picture of the fermentative metabolic traits found in the S. cerevisiae species under wine making conditions. Considerable phenotypic variation was found suggesting that this yeast employs diverse metabolic strategies to face environmental constraints. Several groups of strains can be distinguished from the entire population on the basis of specific traits. Strains accustomed to growing in the presence of high sugar concentrations, such as wine yeasts and strains obtained from fruits, were able to achieve fermentation, whereas natural yeasts isolated from “poor-sugar” environments, such as oak trees or plants, were not. Commercial wine yeasts clearly appeared as a subset of vineyard isolates, and were mainly differentiated by their fermentative performances as well as their low acetate production. Overall, the emergence of the origin-dependent properties of the strains provides evidence for a phenotypic evolution driven by environmental constraints and/or human selection within S. cerevisiae

The Novel Candida albicans Transporter Dur31 Is a Multi-Stage Pathogenicity Factor

Candida albicans is the most frequent cause of oral fungal infections. However, the exact pathogenicity mechanisms that this fungus employs are largely unknown and many of the genes expressed during oral infection are uncharacterized. In this study we sought to functionally characterize 12 previously unknown function genes associated with oral candidiasis. We generated homozygous knockout mutants for all 12 genes and analyzed their interaction with human oral epithelium in vitro. Eleven mutants caused significantly less epithelial damage and, of these, deletion of orf19.6656 (DUR31) elicited the strongest reduction in pathogenicity. Interestingly, DUR31 was not only involved in oral epithelial damage, but in multiple stages of candidiasis, including surviving attack by human neutrophils, endothelial damage and virulence in vivo. In silico analysis indicated that DUR31 encodes a sodium/substrate symporter with 13 transmembrane domains and no human homologue. We provide evidence that Dur31 transports histatin 5. This is one of the very first examples of microbial driven import of this highly cytotoxic antimicrobial peptide. Also, in contrast to wild type C. albicans, dur31Δ/Δ was unable to actively increase local environmental pH, suggesting that Dur31 lies in the extracellular alkalinization hyphal auto-induction pathway; and, indeed, DUR31 was required for morphogenesis. In agreement with this observation, dur31Δ/Δ was unable to assimilate the polyamine spermidine

Computing with bacterial constituents, cells and populations: from bioputing to bactoputing

The relevance of biological materials and processes to computing—aliasbioputing—has been explored for decades. These materials include DNA, RNA and proteins, while the processes include transcription, translation, signal transduction and regulation. Recently, the use of bacteria themselves as living computers has been explored but this use generally falls within the classical paradigm of computing. Computer scientists, however, have a variety of problems to which they seek solutions, while microbiologists are having new insights into the problems bacteria are solving and how they are solving them. Here, we envisage that bacteria might be used for new sorts of computing. These could be based on the capacity of bacteria to grow, move and adapt to a myriad different fickle environments both as individuals and as populations of bacteria plus bacteriophage. New principles might be based on the way that bacteria explore phenotype space via hyperstructure dynamics and the fundamental nature of the cell cycle. This computing might even extend to developing a high level language appropriate to using populations of bacteria and bacteriophage. Here, we offer a speculative tour of what we term bactoputing, namely the use of the natural behaviour of bacteria for calculating

Analityczny model optymalnej wydajności systemu nawadniania

The size and stability of yield per hectare of agricultural crops are greatly affected by climatic conditions, temperature, solar radiation, but especially the quantity and quality of rainfall, which for most agricultural crops is insufficient. Building large-scale irrigation systems is difficult in terms of investment, as well as operating costs. Claimed agricultural yields often do not emanate from a set of certain claims for each of the crops, but are only an estimate based upon empirical experience. Precise determination of these data is very difficult and without the use of exact mathematical methods and information technology would be virtually impossible. Goal of this project is dedicated to enhance of an irrigation system analytical model usability, which would allow the determination of the optimal capacity of the irrigation system in response to microclimate and soil conditions with respect to the crops and irrigation facilities. Developing new methods of precise irrigation is the way of higher and ecological productivity in agricultural production subsystem.Wielkość oraz stabilność plonu z hektara uprawianego pola w dużej mierze zależy od warunków klimatycznych, temperatury, promieniowania słonecznego, ale w szczególny sposób od jakości oraz ilości opadów deszczowych. Opady te dla większości upraw rolniczych są niewystarczające. Oszacowanie wydajności systemu nawadniania nie wynika zatem jedynie z zapotrzebowania na wodę uprawianych roślin, lecz także zależy od czynników losowych - mikroklimatycznych. Aktualnie wydajność systemu nawadniania, wielkości jedynie przybliżonej, szacuje się często na podstawie doświadczeń empirycznych. Dokładne określenie wydajności systemu nawadniania jest bardzo trudne i praktycznie niemożliwe bez zastosowania dokładnych metod matematycznych oraz technologii informatycznych. Celem pracy było zwiększenie użyteczności matematycznego modelu systemu nawadniania, co powinno pozwolić na określenie optymalnej wydajności systemu nawadniania w zależności od mikroklimatu i warunków gruntowych, z uwzględnieniem upraw oraz urządzeń nawadniających

Porównanie metod interpolacyjnych w celu oceny temperatury powietrza

The present article deals with the estimation of air temperature with selected spatial interpolation methods. There are a number of methods of spatial interpolation, which allows to estimate the values if they are not available measurement data. One of the important indicators for many practical analyses is the air temperature. It is well known fact that the air temperature is dependent on the altitude. However, not all of the interpolation methods in their algorithms allow to take into account this important factor that can significantly affect the final estimate. For the estimation of air temperature were chosen method IDS (Inverse Distance Squared) and its modification GIDS (gradient plus inverse distance squared) and GIDS-a. The first method was implemented directly in the software. For the method GIDS and - a GIDS was created application through VBA.Prezentowany artykuł omawia zagadnienie oceny temperatury powietrza za pomocą wybranych przestrzennych metod interpolacyjnych. Istnieje wiele metod przestrzennej interpolacji, które pozwalają na ocenę wartości, jeśli dane pomiarowe nie są dostępne. Jednym z ważnych wskaźników do wielu praktycznych analiz jest temperatura powietrza. Jest wiadomym faktem, że jest ona zależna od wysokości. Jednakże, nie wszystkie metody interpolacyjne w swych algorytmach pozwalają na wzięcie pod uwagę tej istotnej zmiennej, która może znacząco wpłynąć na końcową wartość estymowanego wskaźnika. Do oceny temperatury powietrza wybrano metodę IDS (metoda odwrotnych kwadratów odległości) oraz jej modyfikację GIDS (gradientowa metoda odwrotnych kwadratów odległości) oraz GIDS-a. Pierwsza metoda została zastosowana bezpośrednio w programie komputerowym. Dla metod GIDS i GIDS-a utworzono aplikację za pośrednictwem VBA

Ocena szacowania potrzeb wodnych roślin na podstawie pomiarów meteorologicznych

Na podstawie pomiarów zarejestrowanych przez dwie automatycznestacje meteorologiczne, położone w Polsce i na Słowacji została obliczona ewapotranspiracja (ET0) według wzoru opracowanego przez Hargreavesa. Uzyskane wyniki porównano ze wzorem odniesienia zalecanego przez FAO, która przyjęła wzór Penmana-Monteitha (PM).Wysoka korelacja pomiędzy modelem odniesienia a wzorem uproszczonym Hergreavesa została pokazana. Różnice dotyczą poziomu ewapotranspiracji opracowanych na podstawie wzorów. Model Hargreaves daje wyższą wartość w porównaniu z formułą PM. W celu zastosowania modelu Penmana-Monteitha w praktyce potrzebne jest wiele parametrów meteorologicznych które są wymagane. Brak dostępu do szczegółowych danych meteorologicznych jest poważnym ograniczeniem. Metoda Hergreavesa może być używana, ale wymaga ona dalszych badań w zarówno w naszych jak i zagranicznych warunkach weryfikacji o czynniki empiryczne

Diagnoscops testing CAN network

W artykule zaprezentowano opis diagnostycznego sposobu badania sieci informacyjnej CAN B pojazdu samochodowego z wykorzystaniem specjalistycznego diagnoskopu Wurth WOW. Przesyłanie wszystkich informacji w pojeździe, a więc sygnałów informacyjnych, czy też sygnałów sterujących (nastawczych) jest realizowane z wykorzystaniem wewnętrznej sieci informacyjnej. Stan techniczny tej sieci a w szczególności jej sprawność bezpośrednio wpływają na właściwą pracę wszystkich systemów w pojeździe, informacyjnych (diagnostycznych), czy też systemów sterujących pracą silnika pojazdu oraz jego systemów bezpieczeństwa.The article presents a descripti on of the method of diagnostic information network CAN-B vehicle with the use of specialized diagnoscope Wurth WOW. Transferring all the information on the vehicle, and hence information signals or control signals (setting) is performed using an internal network. The technical condition of the network and in particular its efficiency directly affect the proper operation of all systems in the vehicle, information (diagnostic), or are systems, engine control of the vehicle and its safety systems