A Competitive Microflora Increases the Resistance of Salmonella typhimurium to Inimical Processes: Evidence for a Suicide Response

1998 ◽  
Vol 64 (4) ◽  
pp. 1323-1327 ◽  
Author(s):  
Timothy G. Aldsworth ◽  
Rachel L. Sharman ◽  
Christine E. R. Dodd ◽  
Gordon S. A. B. Stewart
Keyword(s):  
Gene Expression ◽  
Salmonella Typhimurium ◽  
Adaptive Response ◽  
Growth Arrest ◽  
Physiological Mechanism ◽  
Exponential Phase ◽  
Freeze Injury ◽  
Enhanced Resistance ◽  
Cell Densities ◽  
Instantaneous Effect

ABSTRACT The presence of a viable competitive microflora at cell densities of 108 CFU ml−1 protects an underlying population of 105 CFU of Salmonella typhimuriumml−1 against freeze injury. The mechanism of enhanced resistance was initially postulated to be via an RpoS-mediated adaptive response. By using an spvRA::luxCDABEreporter we have shown that although the onset of RpoS-mediated gene expression was brought forward by the addition of a competitive microflora, the time taken for induction was measured in hours. Since the protective effect of a competitive microflora is essentially instantaneous, the stationary-phase adaptive response is excluded as the physiological mechanism. The only instantaneous effect of the competitive microflora was a reduction in the percent saturation of oxygen from 100% to less than 10%. For both mild heat treatment (55°C) and freeze injury this change in oxygen tension affordsSalmonella a substantive (2 orders of magnitude) enhancement in survival. By reducing the levels of dissolved oxygen through active respiration, a competitive microflora reduces oxidative damage to exponential-phase cells irrespective of the inimical treatment. These results have led us to propose a suicide hypothesis for the destruction of rapidly growing cells by inimical processes. In essence, the suicide hypothesis proposes that a mild inimical process leads to the growth arrest of exponential-phase cells and to the decoupling of anabolic and catabolic metabolism. The result of this is a free radical burst which is lethal to unadapted cells.

scholarly journals Conceptual Model of Biofilm Antibiotic Tolerance That Integrates Phenomena of Diffusion, Metabolism, Gene Expression, and Physiology

2019 ◽  
Vol 201 (22) ◽  
Author(s):  
Philip S. Stewart ◽  
Ben White ◽  
Laura Boegli ◽  
Timothy Hamerly ◽  
Kerry S. Williamson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stress Responses ◽  
Specific Growth ◽  
Growth Arrest ◽  
Reaction Diffusion ◽  
Exponential Phase ◽  
Antibiotic Tolerance ◽  
Planktonic Cells ◽  
Concentration Gradients ◽  
Reaction Diffusion Model

ABSTRACT Transcriptomic, metabolomic, physiological, and computational modeling approaches were integrated to gain insight into the mechanisms of antibiotic tolerance in an in vitro biofilm system. Pseudomonas aeruginosa biofilms were grown in drip flow reactors on a medium composed to mimic the exudate from a chronic wound. After 4 days, the biofilm was 114 μm thick with 9.45 log10 CFU cm−2. These biofilms exhibited tolerance, relative to exponential-phase planktonic cells, to subsequent treatment with ciprofloxacin. The specific growth rate of the biofilm was estimated via elemental balances to be approximately 0.37 h−1 and with a reaction-diffusion model to be 0.32 h−1, or one-third of the maximum specific growth rate for planktonic cells. Global analysis of gene expression indicated lower transcription of ribosomal genes and genes for other anabolic functions in biofilms than in exponential-phase planktonic cells and revealed the induction of multiple stress responses in biofilm cells, including those associated with growth arrest, zinc limitation, hypoxia, and acyl-homoserine lactone quorum sensing. Metabolic pathways for phenazine biosynthesis and denitrification were transcriptionally activated in biofilms. A customized reaction-diffusion model predicted that steep oxygen concentration gradients will form when these biofilms are thicker than about 40 μm. Mutant strains that were deficient in Psl polysaccharide synthesis, the stringent response, the stationary-phase response, and the membrane stress response exhibited increased ciprofloxacin susceptibility when cultured in biofilms. These results support a sequence of phenomena leading to biofilm antibiotic tolerance, involving oxygen limitation, electron acceptor starvation and growth arrest, induction of associated stress responses, and differentiation into protected cell states. IMPORTANCE Bacteria in biofilms are protected from killing by antibiotics, and this reduced susceptibility contributes to the persistence of infections such as those in the cystic fibrosis lung and chronic wounds. A generalized conceptual model of biofilm antimicrobial tolerance with the following mechanistic steps is proposed: (i) establishment of concentration gradients in metabolic substrates and products; (ii) active biological responses to these changes in the local chemical microenvironment; (iii) entry of biofilm cells into a spectrum of states involving alternative metabolisms, stress responses, slow growth, cessation of growth, or dormancy (all prior to antibiotic treatment); (iv) adaptive responses to antibiotic exposure; and (v) reduced susceptibility of microbial cells to antimicrobial challenges in some of the physiological states accessed through these changes.

scholarly journals Insights into the Mechanism of Bovine Spermiogenesis Based on Comparative Transcriptomic Studies

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 80
Author(s):  
Xin Li ◽  
Chenying Duan ◽  
Ruyi Li ◽  
Dong Wang
Keyword(s):  
Gene Expression ◽  
Semen Quality ◽  
Regulation Of Gene Expression ◽  
Physiological Mechanism ◽  
Interaction Network ◽  
Seminiferous Tubules ◽  
Differential Analysis ◽  
Epididymal Sperm ◽  
Bioinformatics Analyses ◽  
Acrosome Formation

To reduce subfertility caused by low semen quality and provide theoretical guidance for the eradication of human male infertility, we sequenced the bovine transcriptomes of round, elongated spermatids and epididymal sperms. The differential analysis was carried out with the reference of the mouse transcriptome, and the homology trends of gene expression to the mouse were also analysed. First, to explore the physiological mechanism of spermiogenesis that profoundly affects semen quality, homological trends of differential genes were compared during spermiogenesis in dairy cattle and mice. Next, Gene Ontology (GO), Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment, protein–protein interaction network (PPI network), and bioinformatics analyses were performed to uncover the regulation network of acrosome formation during the transition from round to elongated spermatids. In addition, processes that regulate gene expression during spermiogenesis from elongated spermatid to epididymal sperm, such as ubiquitination, acetylation, deacetylation, and glycosylation, and the functional ART3 gene may play important roles during spermiogenesis. Therefore, its localisation in the seminiferous tubules and epididymal sperm were investigated using immunofluorescent analysis, and its structure and function were also predicted. Our findings provide a deeper understanding of the process of spermiogenesis, which involves acrosome formation, histone replacement, and the fine regulation of gene expression.

MAPK Cascades in Cell Growth and Death

Physiology ◽  
1997 ◽  
Vol 12 (6) ◽  
pp. 286-293 ◽  
Author(s):  
JT Neary
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Cellular Proliferation ◽  
Inflammatory Diseases ◽  
Growth Arrest ◽  
Therapeutic Strategies ◽  
Extracellular Signals ◽  
Mapk Cascades ◽  
Proliferation And Differentiation ◽  
Signaling Components

Distinct signal transduction cascades comprised of at least three proteinkinases mediate cellular proliferation and differentiation, growth arrest, and programmed cell death. These cytosolic enzymes relay extracellular signals from cell surface to nucleus, leading to changes in gene expression. Signaling components of these cascades offer new possibilities for therapeutic strategies in tumorigenesis, inflammatory diseases, immunopotentiation, wound healing, and regeneration.

scholarly journals A ‘phenotypic hangover’ – the predictive adaptive response and multigenerational effects of altered nutrition on the transcriptome of Drosophila melanogaster

2017 ◽  
Author(s):  
Amy J. Osborne ◽  
Peter K. Dearden
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Adaptive Response ◽  
Communicable Disease ◽  
Later Life ◽  
Standard Diet ◽  
Expression Of Genes ◽  
Postnatal Environment ◽  
Predictive Adaptive Response ◽  
Epigenetic Processes

AbstractThe Developmental Origins of Health and Disease (DOHaD) hypothesis predicts that early-life environmental exposures can be detrimental to later-life health, and that mismatch between the pre- and postnatal environment may contribute to the growing non-communicable disease (NCD) epidemic. Within this is an increasingly recognised role for epigenetic mechanisms; epigenetic modifications can be influenced by, e.g., nutrition, and can alter gene expression in mothers and offspring. Currently, there are no whole-genome transcriptional studies of response to nutritional alteration. Thus, we sought to explore how nutrition affects the expression of genes involved in epigenetic processes in Drosophila melanogaster. We manipulated Drosophila food macronutrient composition at the F0 generation, mismatched F1 offspring back to a standard diet, and analysed the transcriptome of the F0 – F3 generations by RNA-sequencing. At F0, the altered (high protein, low carbohydrate, HPLC) diet increased expression of genes involved in epigenetic processes, with coordinated downregulation of genes involved in immunity, neurotransmission and neurodevelopment, oxidative stress and metabolism. Upon reversion to standard nutrition, mismatched F1 and F2 generations displayed multigenerational inheritance of altered gene expression. By the F3 generation, gene expression had reverted to F0 (matched) levels. These nutritionally-induced gene expression changes demonstrate that dietary alteration can upregulate epigenetic genes, which may influence the expression of genes with broad biological functions. Further, the multigenerational inheritance of the gene expression changes in F1 and F2 mismatched generations suggests a predictive adaptive response (PAR) to maternal nutrition. Our findings may help to understand the interaction between maternal diet and future offspring health, and have direct implications for the current NCD epidemic.

scholarly journals Mechanisms of short-term and long-term adaptation

2020 ◽  
pp. 77-86
Author(s):  
Н.Б. Панкова
Keyword(s):  
Gene Expression ◽  
Epigenetic Regulation ◽  
Adaptive Response ◽  
Educational Environment ◽  
Stress Factors ◽  
Short Term ◽  
Functional Reserve ◽  
Short Term Adaptation ◽  
Expression Program

В лекции рассмотрены общие представления об адаптации, основанные на классических работах Г. Селье, Ф.З. Меерсона, Н.А. Агаджаняна, а также особенности адаптивного ответа развивающегося организма. Рассмотрены механизмы срочной адаптации как мобилизации функциональных резервов организма. В качестве одного из механизмов долговременной адаптации представлена эпигенетическая регуляция, которая позволяет выбрать и реализовать программу экспрессии генов - в соответствии с этапом онтогенетического развития, или средовым окружением. В качестве ещё одного механизма долговременной адаптации рассмотрено воздействие на генетический материал. Приведены примеры формирования адаптивного ответа организма на физико-химические и климатогеографические стрессорные факторы. Отдельно проанализированы механизмы адаптивного ответа организма детей на факторы образовательной среды. The lecture addresses general ideas about adaptation based on classic studies by H. Selye, F.Z. Meerson, and N.A. Agadzhanyan and features of the adaptive response in a developing body. Mobilization of the functional reserve is considered as a mechanism of short-term adaptation. Epigenetic regulation is presented as one of mechanisms for long-term adaptation, which allows selecting and implementing a gene expression program consistent with the stage of ontogenetic development or the environment. Another mechanism of long-term adaptation is influence on the genome. The lecture provides examples of adaptation to physicochemical and climatic geographical stress factors. Mechanisms of the adaptive response to factors of the educational environment in children are analyzed separately.

Adrenergic induction of bimodal myocardial protection: signal transduction and cardiac gene reprogramming

1999 ◽  
Vol 276 (5) ◽  
pp. R1525-R1533 ◽  
Author(s):  
Xianzhong Meng ◽  
Brian D. Shames ◽  
Edward J. Pulido ◽  
Daniel R. Meldrum ◽  
Lihua Ao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Adaptive Response ◽  
Ischemia Reperfusion ◽  
Functional Adaptation ◽  
Immunofluorescent Staining ◽  
Northern Analysis ◽  
Cardiac Gene Expression ◽  
Cardiac Gene

This study tested the hypothesis that in vivo norepinephrine (NE) treatment induces bimodal cardiac functional protection against ischemia and examined the roles of α1-adrenoceptors, protein kinase C (PKC), and cardiac gene expression in cardiac protection. Rats were treated with NE (25 μg/kg iv). Cardiac functional resistance to ischemia-reperfusion (25/40 min) injury was examined 30 min and 1, 4, and 24 h after NE treatment with the Langendorff technique, and effects of α1-adrenoceptor antagonism and PKC inhibition on the protection were determined. Northern analysis was performed to examine cardiac expression of mRNAs encoding α-actin and myosin heavy chain (MHC) isoforms. Immunofluorescent staining was performed to localize PKC-βI in the ventricular myocardium. NE treatment improved postischemic functional recovery at 30 min, 4 h, and 24 h but not at 1 h. Pretreatment with prazosin or chelerythrine abolished both the early adaptive response at 30 min and the delayed adaptive response at 24 h. NE treatment induced intranuclear translocation of PKC-βI in cardiac myocytes at 10 min and increased skeletal α-actin and β-MHC mRNAs in the myocardium at 4–24 h. These results demonstrate that in vivo NE treatment induces bimodal myocardial functional adaptation to ischemia in a rat model. α1-Adrenoceptors and PKC appear to be involved in signal transduction for inducing both the early and delayed adaptive responses. The delayed adaptive response is associated with the expression of cardiac genes encoding fetal contractile proteins, and PKC-βI may transduce the signal for reprogramming of cardiac gene expression.

scholarly journals Unraveling the regulation of sophorolipid biosynthesis in Starmerella bombicola

2020 ◽  
Vol 20 (3) ◽  
Author(s):  
Sofie Lodens ◽  
Sophie L K W Roelants ◽  
Goedele Luyten ◽  
Robin Geys ◽  
Pieter Coussement ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stationary Phase ◽  
Gene Cluster ◽  
Biosynthetic Gene Cluster ◽  
Exponential Phase ◽  
Biosynthetic Gene ◽  
Reporter System ◽  
Gfp Expression ◽  
Qpcr Analysis ◽  
Starmerella Bombicola

ABSTRACT Starmerella bombicola very efficiently produces the secondary metabolites sophorolipids (SLs). Their biosynthesis is not-growth associated and highly upregulated in the stationary phase. Despite high industrial and academic interest, the underlying regulation of SL biosynthesis remains unknown. In this paper, potential regulation of SL biosynthesis through the telomere positioning effect (TPE) was investigated, as the SL gene cluster is located adjacent to a telomere. An additional copy of this gene cluster was introduced elsewhere in the genome to investigate if this results in a decoy of regulation. Indeed, for the new strain, the onset of SL production was shifted to the exponential phase. This result was confirmed by RT-qPCR analysis. The TPE effect was further investigated by developing and applying a suitable reporter system for this non-conventional yeast, enabling non-biased comparison of gene expression between the subtelomeric CYP52M1- and the URA3 locus. This was done with a constitutive endogenous promotor (pGAPD) and one of the endogenous promotors of the SL biosynthetic gene cluster (pCYP52M1). A clear positioning effect was observed for both promotors with significantly higher GFP expression levels at the URA3 locus. No clear GFP upregulation was observed in the stationary phase for any of the new strains.

scholarly journals Screening of Differentially Expressed Microsporidia Genes from Nosema ceranae Infected Honey Bees by Suppression Subtractive Hybridization

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 199
Author(s):  
Zih-Ting Chang ◽  
Chong-Yu Ko ◽  
Ming-Ren Yen ◽  
Yue-Wen Chen ◽  
Yu-Shin Nai
Keyword(s):  
Gene Expression ◽  
Real Time ◽  
Differentially Expressed Genes ◽  
Honey Bees ◽  
Physiological Mechanism ◽  
Subtractive Hybridization ◽  
Infection Process ◽  
Nosema Ceranae ◽  
Differentially Expressed ◽  
Suppressive Subtractive Hybridization

The microsporidium Nosema ceranae is a high prevalent parasite of the European honey bee (Apis mellifera). This parasite is spreading across the world into its novel host. The developmental process, and some mechanisms of N. ceranae-infected honey bees, has been studied thoroughly; however, few studies have been carried out in the mechanism of gene expression in N. ceranae during the infection process. We therefore performed the suppressive subtractive hybridization (SSH) approach to investigate the candidate genes of N. ceranae during its infection process. All 96 clones of infected (forward) and non-infected (reverse) library were dipped onto the membrane for hybridization. A total of 112 differentially expressed sequence tags (ESTs) had been sequenced. For the host responses, 20% of ESTs (13 ESTs, 10 genes, and 1 non-coding RNA) from the forward library and 93.6% of ESTs (44 ESTs, 28 genes) from the reverse library were identified as differentially expressed genes (DEGs) of the hosts. A high percentage of DEGs involved in catalytic activity and metabolic processes revealed that the host gene expression change after N. ceranae infection might lead to an unbalance of physiological mechanism. Among the ESTs from the forward library, 75.4% ESTs (49 ESTs belonged to 24 genes) were identified as N. ceranae genes. Out of 24 N. ceranae genes, nine DEGs were subject to real-time quantitative reverse transcription PCR (real-time qRT-PCR) for validation. The results indicated that these genes were highly expressed during N. ceranae infection. Among nine N. ceranae genes, one N. ceranae gene (AAJ76_1600052943) showed the highest expression level after infection. These identified differentially expressed genes from this SSH could provide information about the pathological effects of N. ceranae. Validation of nine up-regulated N. ceranae genes reveal high potential for the detection of early nosemosis in the field and provide insight for further applications.

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