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Bet hedging

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 7, 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...
February 26, 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 conditions1 . The direct antagonism of competitor cells is thus an important bacterial survival strategy2 . 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...
February 19, 2018: Nature Microbiology
Weigel W A, 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...
January 31, 2018: Microbes and Infection
Chadrick E Denlinger
No abstract text is available yet for this article.
January 17, 2018: Journal of Thoracic and Cardiovascular Surgery
Yusuke Horinouchi, Tatsuya Togashi
Within-clutch gamete size variability in Monostroma angicava. In many organisms, it is unclear how the size variation in gametes is generated in each clutch (i.e., total gametes produced by a gametophyte for a single spawning) or how gamete size is adjusted. Within-clutch variation in gamete size has been explained as a result of either physiological/developmental constraints or bet hedging during gametogenesis. These two explanations have been assumed to be mutually exclusive, and related observations are conflicting...
February 1, 2018: Plant Reproduction
Eric Libby, William W Driscoll, William C Ratcliff
Programmed cell death (PCD) occurs in both unicellular and multicellular organisms. While PCD plays a key role in the development and maintenance of multicellular organisms, explaining why single-celled organisms would evolve to actively commit suicide has been far more challenging. Here, we explore the potential for PCD to act as an accessory to microbial bet-hedging strategies that utilize stochastic phenotype switching. We consider organisms that face unpredictable and recurring disasters, in which fitness depends on effective phenotypic diversification...
January 18, 2018: Scientific Reports
Andreas Mayer, Thierry Mora, Olivier Rivoire, Aleksandra M Walczak
Biological populations are subject to fluctuating environmental conditions. Different adaptive strategies can allow them to cope with these fluctuations: specialization to one particular environmental condition, adoption of a generalist phenotype that compromises between conditions, or population-wise diversification (bet hedging). Which strategy provides the largest selective advantage in the long run depends on the range of accessible phenotypes and the statistics of the environmental fluctuations. Here, we analyze this problem in a simple mathematical model of population growth...
September 2017: Physical Review. E
Jonathan P Caulkins
Cannabis legalization is often falsely depicted as a binary choice between status quo prohibition and legalizing production and distribution by (regulated) for-profit industry. There are, however, many more prudent architectures for legalization, such as restricting production and distribution licenses to not-for-profit entities. Wilkins describes how New Zealand applied that concept to gambling machines and proposes a parallel for cannabis legalization. Greater investment in proposing good designs along these lines, including attending to governance structures, would be valuable...
March 2018: International Journal on Drug Policy
Johanna Sunde, Carl Tamario, Petter Tibblin, Per Larsson, Anders Forsman
Environmental heterogeneity is a key determinant of genetic and phenotypic diversity. Stable and homogenous environments tends to result in evolution of specialism and local adaptations, while temporally unpredictable environments may maintain a diversity of specialists, promote generalist strategies, or favour diversified bet hedging strategies. We compared salinity tolerance between two anadromous subpopulations of pike (Esox Lucius) that utilize freshwater spawning sites with different salinity regimes. Eggs from each population were artificially fertilized and incubated in a salinity gradient (0, 3, 5, 7, and 9 psu) using a split-brood design...
January 8, 2018: Scientific Reports
William R Shoemaker, Jay T Lennon
Dormancy is a bet-hedging strategy that allows organisms to persist through conditions that are suboptimal for growth and reproduction by entering a reversible state of reduced metabolic activity. Dormancy allows a population to maintain a reservoir of genetic and phenotypic diversity (i.e., a seed bank) that can contribute to the long-term survival of a population. This strategy can be potentially adaptive and has long been of interest to ecologists and evolutionary biologists. However, comparatively little is known about how dormancy influences the fundamental evolutionary forces of genetic drift, mutation, selection, recombination, and gene flow...
January 2018: Evolutionary Applications
Øystein Nordeide Kielland, Claus Bech, Sigurd Einum
Diversified bet-hedging (DBH) by production of within-genotype phenotypic variance may evolve to maximize fitness in stochastic environments. Bet-hedging is generally associated with parental effects, but phenotypic variation may also develop throughout life via developmental instability (DI). This opens for the possibility of a within-generation mechanism creating DBH during the lifetime of individuals. If so, DI could in fact be a plastic trait itself; if a fluctuating environment indicates uncertainty about future conditions, sensing such fluctuations could trigger DI as a DBH response...
December 2017: Ecology and Evolution
Anne Thonig, Gary Thomas Banta, Benni Winding Hansen, K Emily Knott
Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegans at four sites in the Danish Isefjord-Roskilde-Fjord estuary at six time points, from March 2014 until February 2015...
December 2017: Ecology and Evolution
Jan-Ulrich Kreft, Caroline M Plugge, Clara Prats, Johan H J Leveau, Weiwen Zhang, Ferdi L Hellweger
Models are important tools in microbial ecology. They can be used to advance understanding by helping to interpret observations and test hypotheses, and to predict the effects of ecosystem management actions or a different climate. Over the past decades, biological knowledge and ecosystem observations have advanced to the molecular and in particular gene level. However, microbial ecology models have changed less and a current challenge is to make them utilize the knowledge and observations at the genetic level...
2017: Frontiers in Microbiology
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