Life Stage and Population Variation in Resistance and Tolerance of Hyalella azteca (Amphipoda) to Low pH

1987 ◽  
Vol 44 (6) ◽  
pp. 1102-1111 ◽  
Author(s):  
R. L. France ◽  
P. M. Stokes
Keyword(s):  
Genetic Basis ◽  
Life Stage ◽  
Population Decline ◽  
Acid Tolerance ◽  
Hyalella Azteca ◽  
Low Ph ◽  
Population Variation ◽  
Population Differences ◽  
Physiological Plasticity ◽  
Neutral Water

Lethality experiments revealed that resistance of Hyalella azteca (Amphipoda) to low pH was directly related to size and developmental stage. Exposure of adults to water below pH 5.0 during pulses of acid snowmelt, or of juveniles to below pH 5.5 through gradual lake acidification, could result in population decline. Hyalella azteca from moderately acidic Ontario lakes (pH 5.6–5.7) survived longer at lethal pH than did amphipods from circumneutral lakes (pH 6.4–7.2) where spring pH depressions do not occur. Resistance and tolerance to low pH was neither readily lost by tolerant amphipods exposed to neutral water for 10 d nor readily gained by nontolerant amphipods exposed to sublethal low pH for a similar duration. This absence of physiological plasticity of individual H. azteca suggests that population differences in acid tolerance may result from processes of selective mortality with or without a genetic basis.

scholarly journals Acid tolerance in early colonizers of oral biofilms

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gabriella Boisen ◽  
Julia R. Davies ◽  
Jessica Neilands
Keyword(s):  
Acid Tolerance ◽  
Low Ph ◽  
Salivary Proteins ◽  
Confocal Scanning Laser Microscopy ◽  
Planktonic Cells ◽  
Tolerance Development ◽  
Salivary Pellicle ◽  
Oral Biofilms ◽  
Acid Tolerant

Abstract Background In caries, low pH drives selection and enrichment of acidogenic and aciduric bacteria in oral biofilms, and development of acid tolerance in early colonizers is thought to play a key role in this shift. Since previous studies have focussed on planktonic cells, the effect of biofilm growth as well as the role of a salivary pellicle on this process is largely unknown. We explored acid tolerance and acid tolerance response (ATR) induction in biofilm cells of both clinical and laboratory strains of three oral streptococcal species (Streptococcus gordonii, Streptococcus oralis and Streptococcus mutans) as well as two oral species of Actinomyces (A. naeslundii and A. odontolyticus) and examined the role of salivary proteins in acid tolerance development. Methods Biofilms were formed on surfaces in Ibidi® mini flow cells with or without a coating of salivary proteins and acid tolerance assessed by exposing them to a challenge known to kill non-acid tolerant cells (pH 3.5 for 30 min) followed by staining with LIVE/DEAD BacLight and confocal scanning laser microscopy. The ability to induce an ATR was assessed by exposing the biofilms to an adaptation pH (pH 5.5) for 2 hours prior to the low pH challenge. Results Biofilm formation significantly increased acid tolerance in all the clinical streptococcal strains (P < 0.05) whereas the laboratory strains varied in their response. In biofilms, S. oralis was much more acid tolerant than S. gordonii or S. mutans. A. naeslundii showed a significant increase in acid tolerance in biofilms compared to planktonic cells (P < 0.001) which was not seen for A. odontolyticus. All strains except S. oralis induced an ATR after pre-exposure to pH 5.5 (P < 0.05). The presence of a salivary pellicle enhanced both acid tolerance development and ATR induction in S. gordonii biofilms (P < 0.05) but did not affect the other bacteria to the same extent. Conclusions These findings suggest that factors such as surface contact, the presence of a salivary pellicle and sensing of environmental pH can contribute to the development of high levels of acid tolerance amongst early colonizers in oral biofilms which may be important in the initiation of caries.

Retardation and Recovery of Growth in Brook Trout Fry (Salvelinus fontinalis) Exposed for Various Durations to Acidified Water

1986 ◽  
Vol 43 (10) ◽  
pp. 2048-2050 ◽  
Author(s):  
W. H. Tam ◽  
P. D. Payson ◽  
R. J. J. Roy
Keyword(s):  
Growth Inhibition ◽  
Growth Rates ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Low Ph ◽  
Fish Growth ◽  
Control Fish ◽  
Treated Fish ◽  
Test Fish ◽  
Neutral Water

Brook trout fry (Salvelinus fontinalis) were exposed to pH 4.66 for various durations up to 141 d and then returned to neutral water. Growth of test fish was in general significantly lower than that of control fish for exposures up to days 45–78. In four of six groups of acid-treated fish, growth eventually recovered and the growth rates were not different from that of control fish. The results suggested that growth inhibition was induced early in the exposure to sublethally low pH and that recovery in the latter phase of the experiment occurred whether pH remained acidic or was readjusted to neutral.

Physiological Correlates of Interspecific Variation in Acid Tolerance in Fish

1988 ◽  
Vol 136 (1) ◽  
pp. 243-258 ◽  
Author(s):  
J. FREDA ◽  
D. G. MCDONALD
Keyword(s):  
Yellow Perch ◽  
Acid Tolerance ◽  
Binding Activity ◽  
Low Ph ◽  
Whole Body ◽  
Salmo Gairdneri ◽  
Survival Times ◽  
Ion Regulation ◽  
Sodium Efflux ◽  
Na Efflux

This study investigated ion regulation in relation to water pH in three species of fish of differing tolerance to low pH (common shiners, Notropis cornutus, most sensitive; rainbow trout, Salmo gairdneri, intermediate; yellow perch, Perca flavescens, least sensitive). Increasing sensitivity to exposure to low pH was characterized by shorter survival times, greater losses of whole-body ions, more complete inhibition of Na+ uptake, and greater stimulation of Na+ efflux, the latter being the most important factor in determining survival. Interspecific variations in acid tolerance were also correlated with Na+ transport characteristics at circumneutral pH; Km was directly correlated and Vmax inversely correlated with acid tolerance. In addition, there were large qualitative differences among the species in the Ca2+-dependence of Na+ efflux. Sodium efflux induced by low pH was markedly Ca2+-dependent in both trout and shiners in a manner consistent with a simple competition between Ca2+ and H+ for gill binding sites. The increased sensitivity of shiners relative to trout was related to lowered Ca2+- binding activity. In contrast, Na+ efflux in perch was virtually unaffected by water [Ca2+]. Similarly, La3+ (a Ca2+ antagonist) stimulated higher Na+ losses from shiners than from trout, but had little effect upon perch. Ionic losses produced by saturating La3+ concentrations were generally lower than those produced by H+, suggesting that Ca2+ displacement is not the only mechanism for increased gill permeability at low pH. Nonetheless, the results obtained are consistent with the notion that acid tolerance may be related to Ca2+-binding activity in some species (e.g. trout and shiners) although not in others (e.g. perch).

scholarly journals Negative Effects of Diurnal Changes in Acidification and Hypoxia on Early-Life Stage Estuarine Fishes

Diversity ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 25 ◽  
Author(s):  
Brooke K. Morrell ◽  
Christopher J. Gobler
Keyword(s):  
Early Life ◽  
Fish Larvae ◽  
Life Stage ◽  
Early Life Stage ◽  
Low Ph ◽  
Sensitivity Threshold ◽  
Diurnal Changes ◽  
Menidia Menidia ◽  
Negative Effects ◽  
Low Do

Estuaries serve as important nursery habitats for various species of early-life stage fish, but can experience cooccurring acidification and hypoxia that can vary diurnally in intensity. This study examines the effects of acidification (pH 7.2–7.4) and hypoxia (dissolved oxygen (DO) ~ 2–4 mg L−1) as individual and combined stressors on four fitness metrics for three species of forage fish endemic to the U.S. East Coast: Menidia menidia, Menidia beryllina, and Cyprinodon variegatus. Additionally, the impacts of various durations of exposure to these two stressors was also assessed to explore the sensitivity threshold for larval fishes under environmentally-representative conditions. C. variegatus was resistant to chronic low pH, while M. menidia and M. beryllina experienced significantly reduced survival and hatch time, respectively. Exposure to hypoxia resulted in reduced hatch success of both Menidia species, as well as diminished survival of M. beryllina larvae. Diurnal exposure to low pH and low DO for 4 or 8 h did not alter survival of M. beryllina, although 8 or 12 h of daily exposure through the 10 days posthatch significantly depressed larval size. In contrast, M. menidia experienced significant declines in survival for all intervals of diel cycling hypoxia and acidification (4–12 h). Exposure to 12-h diurnal hypoxia generally elicited negative effects equal to, or of greater severity, than chronic exposure to low DO at the same levels despite significantly higher mean DO exposure concentrations. This evidences a substantial biological cost to adapting to changing DO levels, and implicates diurnal cycling of DO as a significant threat to fish larvae in estuaries. Larval responses to hypoxia, and to a lesser extent acidification, in this study on both continuous and diurnal timescales indicate that estuarine conditions throughout the spawning and postspawn periods could adversely affect stocks of these fish, with diverse implications for the remainder of the food web.

scholarly journals Identification and Inactivation of Genetic Loci Involved with Lactobacillus acidophilus Acid Tolerance

2004 ◽  
Vol 70 (9) ◽  
pp. 5315-5322 ◽  
Author(s):  
M. Andrea Azcarate-Peril ◽  
Eric Altermann ◽  
Rebecca L. Hoover-Fitzula ◽  
Raul J. Cano ◽  
Todd R. Klaenhammer
Keyword(s):  
Amino Acid ◽  
Lactobacillus Acidophilus ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Low Ph ◽  
Open Reading Frames ◽  
Amino Acid Permease ◽  
Physiological Limits ◽  
Insertional Inactivation ◽  
Genes Encoding

ABSTRACT Amino acid decarboxylation-antiporter reactions are one of the most important systems for maintaining intracellular pH between physiological limits under acid stress. We analyzed the Lactobacillus acidophilus NCFM complete genome sequence and selected four open reading frames with similarities to genes involved with decarboxylation reactions involved in acid tolerance in several microorganisms. Putative genes encoding an ornithine decarboxylase, an amino acid permease, a glutamate γ-aminobutyrate antiporter, and a transcriptional regulator were disrupted by insertional inactivation. The ability of L. acidophilus to survive low-pH conditions, such as those encountered in the stomach or fermented dairy foods, was investigated and compared to the abilities of early- and late-stationary-phase cells of the mutants by challenging them with a variety of acidic conditions. All of the integrants were more sensitive to low pH than the parental strain. Interestingly, each integrant also exhibited an adaptive acid response during logarithmic growth, indicating that multiple mechanisms are present and orchestrated in L. acidophilus in response to acid challenge.

Empirical Hypothesis to Explain the Restricted Distribution of Hyalella azteca (Amphipoda) in Anthropogenically Acidified Lakes

1987 ◽  
Vol 44 (6) ◽  
pp. 1112-1121 ◽  
Author(s):  
Robert L. France ◽  
Bruce D. LaZerte
Keyword(s):  
Littoral Zone ◽  
Time Trend ◽  
Population Decline ◽  
Hyalella Azteca ◽  
Ecological Data ◽  
Short Term ◽  
Restricted Distribution ◽  
Empirical Hypothesis ◽  
Acidified Lakes ◽  
Plastic Lake

A simple and speculative model is proposed to explain the restricted distribution of Hyalella azteca (Amphipoda) within acidified Ontario lakes. The model integrates field chemical and ecological data with results from laboratory toxicological experiments. Frequent spring depressions of pH to below 5.0, measured in the littoral zone of Plastic Lake during 1982, were predicted to cause a mortality of 35.2% to a theoretically constructed amphipod population. A time trend simulation suggested that population decline of H. azteca in similar anthropogenically acidified lakes could be caused by such direct mortality due to short-term pH fluctuations. Assumptions and factors not considered by the model which could exacerbate or mitigate the effects of acidic snowmelt to H. azteca are discussed.

Lethality of Low pH and Al to Early Life Stages of Six Fish Species Inhabiting PreCambrian Shield Waters in Ontario

1989 ◽  
Vol 46 (7) ◽  
pp. 1188-1202 ◽  
Author(s):  
K. E. Holtze ◽  
N. J. Hutchinson
Keyword(s):  
Largemouth Bass ◽  
Early Life ◽  
Life Stage ◽  
Early Life Stage ◽  
Low Ph ◽  
Smallmouth Bass ◽  
Life Stages ◽  
White Sucker ◽  
Lake Whitefish ◽  
Early Life Stages

Lethality of low pH and Al to egg and fry stages of common shiner (Notropis cornutus), white sucker (Catostomus commersoni), walleye (Stizostedion vitreum), lake whitefish (Coregonus clupeaformis), smallmouth bass (Micropterus dolomieui), and largemouth bass (M. salmoides) was determined in a series of laboratory tests in soft (Ca = 4.0 mg/L) water. Low pH was lethal to cleavage eggs in the first 4 d of exposure, to eyed eggs in the immediate prehatch period and to fry following their transition to branchial respiration. Early life stage response to Al was determined by their sensitivity to low pH. Al prolonged survival of cleavage eggs at pH = 4.2, was detrimental to eyed eggs and fry at pH 4.4–5.4 and was most lethal within 0.3 pH units of the pH which was lethal in the absence of Al. In situ distribution of four of the six species was adequately explained by lethality of low pH alone to cleavage eggs or fry. Sensitivity to low pH and Al produced estimates of pH > 5.9 (common shiner), pH > 5.4 (lake whitefish, white sucker, walleye), and pH > 5.1 (smallmouth and largemouth bass) for survival of early life stages in acidified waters.

scholarly journals Identification of Salmonella enterica Serovar Typhimurium Genes Important for Survival in the Swine Gastric Environment

2006 ◽  
Vol 72 (4) ◽  
pp. 2829-2836 ◽  
Author(s):  
Shawn M. D. Bearson ◽  
Bradley L. Bearson ◽  
Mark A. Rasmussen
Keyword(s):  
Lactic Acid ◽  
Salmonella Enterica ◽  
Ex Vivo ◽  
Stomach Contents ◽  
Acid Tolerance ◽  
Lethal Effect ◽  
Gastric Fluid ◽  
Low Ph ◽  
Chromatography Analysis ◽  
Serovar Typhimurium

ABSTRACT Since the stomach is a first line of defense for the host against ingested microorganisms, an ex vivo swine stomach contents (SSC) assay was developed to search for genes important for Salmonella enterica serovar Typhimurium survival in the hostile gastric environment. Initial characterization of the SSC assay (pH 3.87) using previously identified, acid-sensitive serovar Typhimurium mutants revealed a 10-fold decrease in survival for a phoP mutant following 20 min of challenge and no survival for mutants of rpoS or fur. To identify additional genes, a signature-tagged mutagenesis bank was constructed and screened in the SSC assay. Nineteen mutants were identified and individually analyzed in the SSC and acid tolerance response assays; 13 mutants exhibited a 10-fold or greater sensitivity in the SSC assay compared to the wild-type strain, but only 3 mutants displayed a 10-fold or greater decrease in survival following pH 3.0 acidic challenge. Further examination determined that the lethal effects of the SSC are pH dependent but that low pH is not the sole killing mechanism(s). Gas chromatography analysis of the SSC revealed lactic acid levels of 126 mM. Upon investigating the effects of lactic acid on serovar Typhimurium survival in a synthetic gastric fluid, not only was a concentration- and time-dependent lethal effect observed, but the phoP, rpoS, fur, and pnp genes were identified as involved in protection against lactic acid exposure. These studies indicate a role in gastric survival for several serovar Typhimurium genes and imply that the stomach environment is defined by more than low pH.

scholarly journals QTL Mapping of a Brazilian Bioethanol Strain Unravels the Cell Wall Protein-Encoding Gene GAS1 as a Major Contributor to Low Ph Tolerance in S. Cerevisiae

2021 ◽  
Author(s):  
Alessandro L V Coradini ◽  
Fellipe da Silveira Bezerra de Mello ◽  
Monique Furlan ◽  
Carla Maneira ◽  
Marcello Falsarella Carazzolle ◽  
...  
Keyword(s):  
Qtl Mapping ◽  
Genetic Architecture ◽  
Genetic Basis ◽  
Acid Resistance ◽  
Low Ph ◽  
Susceptible Strain ◽  
Yeast Cells ◽  
Synonymous Mutation ◽  
Major Contributor ◽  
Ph Tolerance

Abstract BACKGROUNDSaccharomyces cerevisiae is largely applied in many biotechnological processes, from traditional food and beverage industries to modern biofuel and biochemicals factories. During the fermentation process, yeast cells are usually challenged in different harsh conditions, which often impact productivity. Regarding bioethanol production, cell exposure to acidic environments is related to productivity loss on both first and second generation ethanol. In this scenario, indigenous strains traditionally used in fermentation stand out as a source of complex genetic architecture, mainly due to their highly robust background - including low pH tolerance. RESULTSIn this work, we pioneer the use of QTL mapping to uncover the genetic basis that endow industrial strain Pedra-2 (PE-2) with outstanding acid resistance. First, we developed a fluorescence-based high-throughput approach to collect a large number of haploid cells using flow cytometry. Then, we were able to apply a bulk segregant analysis to solve the genetic basis of low pH resistance in PE-2, which uncovered a region in chromosome XIII as the major QTL associated with the evaluated phenotype. A reciprocal hemizygosity analysis revealed allele GAS1, encoding a β-1,3-glucanosyltransferase, as the major contributor to this phenotype. The GAS1 sequence alignment of 48 S. cerevisiae strains pointed out a non-synonymous mutation (T211A) prevalence in wild type isolates, which is absent in laboratory strains. We further showcase that GAS1 allele swap between PE-2 and a low pH-susceptible strain can improve cell viability on the latter of up to 12% after a sulfuric acid wash process.CONCLUSIONThis work revealed GAS1 as the major causative gene associated with low pH resistance in PE-2, harboring a non-synonymous mutation persistent in industrial strains. We also showcase how GAS1PE-2 can improve acid resistance of a susceptible strain, suggesting that these findings can be a powerful foundation for the development of more robust and acid-tolerant strains for the industrial production of economically-relevant goods. Our results collectively show the importance of tailored industrial isolated strains in the discovery of the genetic architecture of relevant traits and its implications over productivity.

scholarly journals Population variation of miRNAs and isomiRs and their impact on human immunity to infection

2020 ◽  
Author(s):  
Maxime Rotival ◽  
Katherine J Siddle ◽  
Martin Silvert ◽  
Julien Pothlichet ◽  
Hélène Quach ◽  
...  
Keyword(s):  
Mirna Expression ◽  
Influenza A ◽  
Population Level ◽  
Population Variation ◽  
European Ancestry ◽  
Population Differences ◽  
Rich Cluster ◽  
Protein Coding ◽  
Expression Variability ◽  
A Minor

ABSTRACTMicroRNAs (miRNAs) are key epigenetic regulators of the immune system, yet their variation and contribution to intra- and inter-population differences in immune responses is poorly characterized. Here, we generated 977 miRNA-sequencing profiles from primary monocytes, from individuals of African and European ancestry, following activation of three TLR pathways (TLR4, TLR1/2 and TLR7/8) or infection with Influenza A virus. We find that immune activation leads to important modifications in the miRNA and isomiR repertoire, particularly in response to viral challenges. These changes are, however, much weaker than those observed for protein-coding genes, suggesting stronger selective constraints on the miRNA response to stimulation. This is supported by the limited genetic control of miRNA expression variability (miR-QTLs) — and the lower occurrence of G×E interactions — in stark contrast with eQTLs that are largely context-dependent. We also detect marked differences in miRNA expression between populations, which are mostly driven by non-genetic factors. Yet, on average, miR-QTLs explain ~60% of population differences in expression of their cognate miRNAs, and, in some cases, evolve adaptively, as shown in Europeans for a miRNA-rich cluster on chromosome 14. Finally, integrating miRNA and mRNA data from the same individuals, we provide evidence that the canonical model of miRNA-driven transcript degradation has a minor impact on miRNA-mRNA correlations, which are, in our setting, mainly driven by co-transcription. Together, our results shed new light onto the factors driving miRNA and isomiR diversity at the population level, and constitute a useful resource for evaluating their role in host differences of immunity to infection.

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