Compensating Effects of Opposing Changes in Putrescine (2+) and K+Concentrations onlacRepressor-lacOperator Binding:in VitroThermodynamic Analysis andin VivoRelevance

Mw, Capp; Ds, Cayley; Zhang, W; Hj, Guttman; Se, Melcher; Rm, Saecker; Cf, Anderson; Mt, Record

doi:10.1006/jmbi.1996.0231

Cited by 56 publications

(61 citation statements)

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“…Polyamines serve many cellular functions in a wide range of organisms (Rhee et al, 2007). One of these functions is to stabilize protein-protein and protein-nucleic acid interactions against changes in intracellular osmolyte levels (Capp et al, 1996). As proposed previously (Whitehead et al, 2011a), increased cellular polyamines may be important for stabilizing genome function in the face of rapid changes in osmolyte concentrations during osmotic challenge in fish, and may serve a similar role in bivalves (Lockwood and Somero, 2011).…”

Section: Water and Cell Volume Regulationmentioning

confidence: 81%

Salinity- and population-dependent genome regulatory response during osmotic acclimation in the killifish (Fundulus heteroclitus) gill

Whitehead

Roach

Zhang

et al. 2012

Journal of Experimental Biology

128

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SUMMARYThe killifish Fundulus heteroclitus is abundant in osmotically dynamic estuaries and it can quickly adjust to extremes in environmental salinity. We performed a comparative osmotic challenge experiment to track the transcriptomic and physiological responses to two salinities throughout a time course of acclimation, and to explore the genome regulatory mechanisms that enable extreme osmotic acclimation. One southern and one northern coastal population, known to differ in their tolerance to hypo-osmotic exposure, were used as our comparative model. Both populations could maintain osmotic homeostasis when transferred from 32 to 0.4p.p.t., but diverged in their compensatory abilities when challenged down to 0.1p.p.t., in parallel with divergent transformation of gill morphology. Genes involved in cell volume regulation, nucleosome maintenance, ion transport, energetics, mitochondrion function, transcriptional regulation and apoptosis showed population-and salinity-dependent patterns of expression during acclimation. Network analysis confirmed the role of cytokine and kinase signaling pathways in coordinating the genome regulatory response to osmotic challenge, and also posited the importance of signaling coordinated through the transcription factor HNF-4. These genome responses support hypotheses of which regulatory mechanisms are particularly relevant for enabling extreme physiological flexibility. Supplementary material available online at

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Section: Water and Cell Volume Regulationmentioning

confidence: 81%

Salinity- and population-dependent genome regulatory response during osmotic acclimation in the killifish (Fundulus heteroclitus) gill

Whitehead

Roach

Zhang

et al. 2012

Journal of Experimental Biology

128

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“…Although polyamines are known to play a critical role in maintaining cell viability and growth under hypoosmotic conditions, for example in mammalian cells (32,33), an apparent role of these molecules in the fish osmo-compensatory response is novel. Maintenance of protein conformation, protein-nucleic acid interactions, and protein synthesis depend critically on intracellular salt concentrations (particularly Na + /K + ) (34)(35)(36), and polyamines help cells buffer these processes against changes in intracellular osmolytes (34). Given the rapid depletion of intracellular osmolytes during cell volume regulation (29,37), upregulation of polyamines is consistent with this protective function.…”

Section: Resultsmentioning

confidence: 96%

Genomic mechanisms of evolved physiological plasticity in killifish distributed along an environmental salinity gradient

Whitehead

Roach

Zhang

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

192

224

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Adaptive variation tends to emerge clinally along environmental gradients or discretely among habitats with limited connectivity. However, in Atlantic killifish (Fundulus heteroclitus), a population genetic discontinuity appears in the absence of obvious barriers to gene flow along parallel salinity clines and coincides with a physiologically stressful salinity. We show that populations resident on either side of this discontinuity differ in their abilities to compensate for osmotic shock and illustrate the physiological and functional genomic basis of population variation in hypoosmotic tolerance. A population native to a freshwater habitat, upstream of the genetic discontinuity, exhibits tolerance to extreme hypoosmotic challenge, whereas populations native to brackish or marine habitats downstream of the discontinuity lose osmotic homeostasis more severely and take longer to recover. Comparative transcriptomics reveals a core transcriptional response associated with acute and acclimatory responses to hypoosmotic shock and posits unique mechanisms that enable extreme osmotic tolerance. Of the genes that vary in expression among populations, those that are putatively involved in physiological acclimation are more likely to exhibit nonneutral patterns of divergence between freshwater and brackish populations. It is not the well-known effectors of osmotic acclimation, but rather the lesser-known immediateearly responses, that appear important in contributing to population differences.adaptive acclimation | ecological genomics | microarray A tlantic killifish (Fundulus heteroclitus) occupy an extremely wide osmotic niche from freshwater to marine, and populations are distributed along steep salinity gradients in Atlantic coast estuaries. In the Chesapeake Bay, salinity gradients are distributed across hundreds of kilometers, although no obvious barriers to gene flow exist across this continuum of osmotic habitats. Because salinity is arguably the most important single physical environmental variable that delimits aquatic species distributions in nature (including Fundulus species; ref. 1), we exploit F. heteroclitus distributed along Chesapeake Bay salinity gradients as a model to discover genes and pathways that enable extreme physiological plasticity and to explore the physiological and functional genomic basis of adaptive microevolution in alternative osmotic environments.Results and Discussion Population Genetic Divergence. We characterized the genetic structure of killifish distributed along two parallel salinity gradients in Chesapeake Bay: one along the Potomac River and the other along the James River (Fig. 1A). Steep clines in allele frequency for both mitochondrial and nuclear markers were centered at nearly identical salinities along the parallel gradients (Fig. 1B). Genotype frequency clines bounded the tidal freshwater transition region (<0.5 ppt) of both rivers, where sites upstream are freshwater year-round according to 20 y of data logged from fixed monitoring stations (www.chesapeakebay.net/ data_...

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“…However, in vitro sensitivity to osmotic conditions may not necessarily correlate with in vivo sensitivity. The relative stability of most protein-DNA interactions in vivo under different osmotic conditions is presumably due to compensatory factors that include increased molecular crowding due to volume exclusion, decreased nonspecific binding, and changes in ionic composition (e.g., increasing glutamate and decreasing putrescine levels), which are believed to occur in vivo upon osmotic upshifts (4,6,39). Therefore, it will be important to a Overnight cultures grown in M9-0.4% glycerol (M9) were subcultured into the same medium and incubated at 37ЊC with shaking for 6 h; 0.3 M NaCl was added to part of the cultures (M9 ϩ NaCl).…”

Section: Discussionmentioning

confidence: 99%

“…KMnO 4 reacts preferentially with unpaired thymines and cytosines and has been used to detect open-complex formation at promoter regions (41). The formation of open complexes at P1 in vivo as a function of osmotic upshift and CRP-cAMP binding was probed by using KMnO 4 . Cells harboring a plasmid containing the wild-type proP regulatory region (pRJ4039) or a plasmid containing the Ϫ41 CRP site mutation (pRJ4060) were grown in M9-glycerol.…”

Section: ϫ345 Crp-camp Is Unable To Prevent Transcription From a Prmentioning

confidence: 99%

Cyclic AMP receptor protein functions as a repressor of the osmotically inducible promoter proP P1 in Escherichia coli

Johnson

1997

J Bacteriol

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Transcription of the proP gene, encoding a transporter of the osmoprotectants proline and glycine betaine, is controlled from two promoters, P1 and P2, that respond primarily to osmotic and stationary-phase signals, respectively. The P1 promoter is normally expressed at a very low level under low or normal medium osmolarity. We demonstrate that the binding of the cyclic AMP (cAMP) receptor protein (CRP) to a site centered at ؊34.5 within the promoter is responsible for the low promoter activity under these conditions. A brief period of reduced CRP binding in early log phase corresponds to a transient burst of P1 transcription upon resumption of growth in Luria-Bertani broth. A CRP binding-site mutation or the absence of a functional crp gene leads to high constitutive expression of P1. We show that the binding of CRP-cAMP inhibits transcription by purified RNA polymerase in vitro at P1, but this repression is relieved at moderately high potassium glutamate concentrations. Likewise, open-complex formation at P1 in vivo is inhibited by the presence of CRP under low-osmolarity conditions. Because P1 expression can be further induced by osmotic upshifts in a ⌬crp strain or in the presence of the CRP binding-site mutation, additional controls exist to osmotically regulate P1 expression.

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Compensating Effects of Opposing Changes in Putrescine (2+) and K+Concentrations onlacRepressor-lacOperator Binding:in VitroThermodynamic Analysis andin VivoRelevance

Cited by 56 publications

References 0 publications

Salinity- and population-dependent genome regulatory response during osmotic acclimation in the killifish (Fundulus heteroclitus) gill

Salinity- and population-dependent genome regulatory response during osmotic acclimation in the killifish (Fundulus heteroclitus) gill

Genomic mechanisms of evolved physiological plasticity in killifish distributed along an environmental salinity gradient

Cyclic AMP receptor protein functions as a repressor of the osmotically inducible promoter proP P1 in Escherichia coli

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