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Bet hedging

Lin Zeng, Lulu Chen, Robert A Burne
Bacteria prioritize sugar metabolism via carbohydrate catabolite repression, which regulates global gene expression to optimize the catabolism of preferred substrates. Here, we report an unusual long-term memory effect in certain Streptococcus mutans strains that alters adaptation to growth on lactose after prior exposure to glucose or fructose. In strain GS-5, cells that were first cultured on fructose then transferred to lactose displayed an exceptionally long lag (>11 h) and slower growth, compared to cells first cultured on glucose or cellobiose, which displayed a reduction in lag phase by as much as 10 h...
May 11, 2018: Applied and Environmental Microbiology
Sophie Cousins
No abstract text is available yet for this article.
May 10, 2018: BMJ: British Medical Journal
Xuan Cheng, Ary A Hoffmann, James L Maino, Paul A Umina
BACKGROUND: The polyphagous mite pest, Halotydeus destructor, typically has three generations during the cool moist season in Australia and produces over-summering diapause eggs in spring. Diapause eggs have a distinct thick and dark chorion and can survive heat, desiccation and the applications of pesticides. Farmers suppress the mite generation producing diapause eggs by a carefully-timed spring pesticide application using Timerite® , which predicts the onset of diapause egg production based largely on daylength...
April 27, 2018: Pest Management Science
Eric Bricker, Ainsley Calladine, Robert Virnstein, Michelle Waycott
Many ecosystems are experiencing rapid transformations due to global environmental change. Understanding how ecological shifts affect species persistence is critical to modern management strategies. The edge of a species range is often where physiological tolerances are in conflict with ability to persist. Extreme examples of clonality over large spatial and temporal scales can occur where the life history of a species allows for it. We examine extreme clonality in an aquatic plant species at the edge if its range...
2018: Frontiers in Plant Science
Mélissa Verin, Aurélien Tellier
Seed (egg) banking is a common bet-hedging strategy maximizing the fitness of organisms facing environmental unpredictability by the delayed emergence of offspring. Yet, this condition often requires fast and drastic stochastic shifts between good and bad years. We hypothesize that the host seed banking strategy can evolve in response to coevolution with parasites because the coevolutionary cycles promote a gradually changing environment over longer times than seed persistence. We study the evolution of host germination fraction as a quantitative trait using both pairwise competition and multiple mutant competition methods, while the germination locus can be genetically linked or unlinked with the host locus under coevolution...
April 20, 2018: Evolution; International Journal of Organic Evolution
Eric Libby, William W Driscoll, William C Ratcliff
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
April 19, 2018: Scientific Reports
Sajjad Awan, Steven Footitt, William E Finch-Savage
Seed vigour is a key trait essential for the production of sustainable and profitable crops. The genetic basis of variation in seed vigour has recently been determined in Brassica oleracea, but the relative importance of the interaction with parental environment is unknown. We produced seeds under a range of maternal environments, including global warming scenarios. Lines were compared that had the same genetic background, but different alleles (high and low vigour) at QTLs responsible for determining seed vigour by altering ABA content and sensitivity...
April 16, 2018: Plant Journal: for Cell and Molecular Biology
Iain G Johnston, George W Bassel
Plants have evolved to exploit stochasticity to hedge bets and ensure robustness to varying environments between generations. In agriculture, environments are more controlled, and this evolved variability decreases potential yields, posing agronomic and food security challenges. Understanding how plant cells generate and harness noise thus presents options for engineering more uniform crop performance. Here, we use stochastic chemical kinetic modelling to analyse a hormone feedback signalling motif in Arabidopsis thaliana seeds that can generate tunable levels of noise in the hormone ABA, governing germination propensity...
April 2018: Journal of the Royal Society, Interface
Bożena Bruhn-Olszewska, Paweł Szczepaniak, Ewelina Matuszewska, Dorota Kuczyńska-Wiśnik, Karolina Stojowska-Swędrzyńska, María Moruno Algara, Ewa Laskowska
Bacteria can form heterogeneous populations containing phenotypic variants of genetically identical cells. The heterogeneity of populations can be considered a bet-hedging strategy allowing adaptation to unknown environmental changes - at least some individual subpopulations or cells might be able to withstand future adverse conditions. Using Percoll gradient centrifugation, we demonstrated that in an Escherichia coli culture exposed to heat shock at 50 °C, two physiologically distinct subpopulations were formed...
April 2018: Microbiological Research
Anirban Ghosh, Özden Baltekin, Marcus Wäneskog, Dina Elkhalifa, Disa L Hammarlöf, Johan Elf, Sanna Koskiniemi
Bacterial populations can use bet-hedging strategies to cope with rapidly changing environments. One example is non-growing cells in clonal bacterial populations that are able to persist antibiotic treatment. Previous studies suggest that persisters arise in bacterial populations either stochastically through variation in levels of global signalling molecules between individual cells, or in response to various stresses. Here, we show that toxins used in contact-dependent growth inhibition (CDI) create persisters upon direct contact with cells lacking sufficient levels of CdiI immunity protein, which would otherwise bind to and neutralize toxin activity...
March 23, 2018: EMBO Journal
Mohit Kumar Jolly, Prakash Kulkarni, Keith Weninger, John Orban, Herbert Levine
It is well known that genetic mutations can drive drug resistance and lead to tumor relapse. Here, we focus on alternate mechanisms-those without mutations, such as phenotypic plasticity and stochastic cell-to-cell variability that can also evade drug attacks by giving rise to drug-tolerant persisters. The phenomenon of persistence has been well-studied in bacteria and has also recently garnered attention in cancer. We draw a parallel between bacterial persistence and resistance against androgen deprivation therapy in prostate cancer (PCa), the primary standard care for metastatic disease...
2018: Frontiers in Oncology
Anna-Lena Heins, Dirk Weuster-Botz
Population heterogeneity is omnipresent in all bioprocesses even in homogenous environments. Its origin, however, is only so well understood that potential strategies like bet-hedging, noise in gene expression and division of labour that lead to population heterogeneity can be derived from experimental studies simulating the dynamics in industrial scale bioprocesses. This review aims at summarizing the current state of the different parts of single cell studies in bioprocesses. This includes setups to visualize different phenotypes of single cells, computational approaches connecting single cell physiology with environmental influence and special cultivation setups like scale-down reactors that have been proven to be useful to simulate large-scale conditions...
March 14, 2018: Bioprocess and Biosystems Engineering
M Polačik, M Reichard, M Vrtílek
Extreme asynchrony in embryo development, a typical feature of annual killifish living in temporary pools, represents a bet-hedging strategy to cope with unpredictable rainfall. African annual killifish are distributed across a large precipitation gradient, raising the potential for local adaptation in the degree of developmental asynchrony (e.g. higher in arid areas, lower in humid areas). Eight populations of two sister species, Nothobranchius furzeri and Nothobranchius kadleci, from sites along the rainfall gradient were tested and compared for asynchrony and duration of embryo development...
March 12, 2018: Journal of Fish Biology
Patrick Kennedy, Andrew D Higginson, Andrew N Radford, Seirian Sumner
The evolution of altruism-costly self-sacrifice in the service of others-has puzzled biologists since The Origin of Species. For half a century, attempts to understand altruism have developed around the concept that altruists may help relatives to have extra offspring in order to spread shared genes. This theory-known as inclusive fitness-is founded on a simple inequality termed Hamilton's rule. However, explanations of altruism have typically not considered the stochasticity of natural environments, which will not necessarily favour genotypes that produce the greatest average reproductive success...
March 15, 2018: Nature
Jeffrey N Carey, Erin L Mettert, Manuela Roggiani, Kevin S Myers, Patricia J Kiley, Mark Goulian
Microbial populations can maximize fitness in dynamic environments through bet hedging, a process wherein a subpopulation assumes a phenotype not optimally adapted to the present environment but well adapted to an environment likely to be encountered. Here, we show that oxygen induces fluctuating expression of the trimethylamine oxide (TMAO) respiratory system of Escherichia coli, diversifying the cell population and enabling a bet-hedging strategy that permits growth following oxygen loss. This regulation by oxygen affects the variance in gene expression but leaves the mean unchanged...
March 22, 2018: Cell
József Garay, Villő Csiszár, Tamás F Móri, András Szilágyi, Zoltán Varga, Szabolcs Számadó
Parent-offspring communication remains an unresolved challenge for biologist. The difficulty of the challenge comes from the fact that it is a multifaceted problem with connections to life-history evolution, parent-offspring conflict, kin selection and signalling. Previous efforts mainly focused on modelling resource allocation at the expense of the dynamic interaction during a reproductive season. Here we present a two-stage model of begging where the first stage models the interaction between nestlings and parents within a nest and the second stage models the life-history trade-offs...
2018: PloS One
Hebah S Mejbel, Andrew M Simons
Environmental unpredictability is known to result in the evolution of bet-hedging traits. Variable dormancy enhances survival through harsh conditions, and is widely cited as a diversification bet-hedging trait. The floating aquatic plant, Spirodela polyrhiza (Greater Duckweed), provides an opportunity to study diversification because although partially reliable seasonal cues exist, its growing season is subject to an unpredictable and literally "hard" termination when the surface water freezes, and overwinter survival depends on a switch from production of normal daughter fronds to production of dense, sinking "turions" prior to freeze-over...
February 2018: Ecology and Evolution
Yu-Cheng Lin, Matthew D Sekedat, William Cole Cornell, Gustavo M Silva, Chinweike Okegbe, Alexa Price-Whelan, Christine Vogel, Lars E P Dietrich
Microbes in biofilms face the challenge of substrate limitation. In particular, cells in Pseudomonas aeruginosa biofilms growing in the laboratory or during host colonization often become limited for oxygen. Previously we found that phenazines, antibiotics produced by P. aeruginosa , balance the intracellular redox state for cells in biofilms. Here, we show that genes involved in denitrification are induced in phenazine-null (Δ phz ) mutant biofilms grown under an aerobic atmosphere, even in the absence of nitrate...
February 20, 2018: Journal of Bacteriology
Kaitlyn D LaCourse, S Brook Peterson, Hemantha D Kulasekara, Matthew C Radey, Jungyun Kim, Joseph D Mougous
Bacteria in polymicrobial habitats contend with a persistent barrage of competitors, often under rapidly changing environmental conditions 1 . The direct antagonism of competitor cells is thus an important bacterial survival strategy 2 . Towards this end, many bacterial species employ an arsenal of antimicrobial effectors with multiple activities; however, the benefits conferred by the simultaneous deployment of diverse toxins are unknown. Here we show that the multiple effectors delivered to competitor bacteria by the type VI secretion system (T6SS) of Pseudomonas aeruginosa display conditional efficacy and act synergistically...
April 2018: Nature Microbiology
W A Weigel, P Dersch
Growing knowledge of the complexity of the host-pathogen interactions during the course of an infection revealed an amazing variability of bacterial pathogens within the same host tissue site. This heterogeneity in bacterial populations is either the result of a different bacterial response to a slightly divergent tissue microenvironment or is caused by a genetic circuit in which small endogenous fluctuations in a small number of transcription factors drive gene expression in combination with a positive feedback loop...
February 1, 2018: Microbes and Infection
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