Gender and Age Differences in the Suppressive Effect of a 50 Hz Electric Field on the Immobilization-Induced Increase of Plasma Glucocorticoid in Mice

We developed an experimental system to characterize the suppressive effect of extremely low-frequency (ELF) electric fields (EFs) on the stress response. We assessed differences in the EF effects by age and gender. Control, EF-alone, immobilization-alone, and co-treated groups were subjected to an EF (50 Hz, 10 kV/m). Co-treated mice were exposed to the EF for 60 min, with immobilization during the latter half. Our results indicate that the suppressive effects of ELF EFs on the stress response in immobilized mice occur regardless of gender or age. As stress plays an important role in the onset and progression of various diseases, these findings may have broad implications for understanding the efficacy of EFs in animal, and perhaps human, health. Bioelectromagnetics. 2020;41:156–163. © 2019 Bioelectromagnetics Society.     

Molecular and functional analysis of the ribosomal L11 and S12 protein genes ( rplK and rpsL ) of Streptomyces coelicolor A3(2)

A RelC deletion mutant, KO-100, of Streptomyces coelicolor A3(2) has been isolated from a collection of spontaneous thiostrepton-resistant mutants. KO-100 grows as vigorously as the parent strain and possesses a 6-bp deletion within the rplK, previously termed relC. When the wild-type rplK gene was propagated on a low-copy-number vector in mutant KO-100, the ability to produce ppGpp, actinorhodin and undecylprodigiosin, which had been lost in the RelC mutant, was completely restored. Allele replacement by gene homogenotization demonstrated that the RelC mutation is responsible for the resistance to thiostrepton and the inactivation of ppGpp, actinorhodin and undecylprodigiosin production. Western blotting showed that ribosomes from the RelC mutant KO-100 contain only one-eighth the amount of L11 protein found in ribosomes of the parent strain. The impairment of antibiotic production in KO-100 could be rescued by the introduction of mutations that confer resistance to streptomycin (str), which result in alteration of Lys-88 in ribosomal protein S12 to Glu or Arg. No accompanying restoration of ppGpp synthesis was detected in these RelC str double mutants. Received: 12 May 1997 / Accepted: 22 July 1997     

Adaptive developmental plasticity: what is it,how can we recognize it and when can it evolve?

Developmental plasticity describes situations where a specific input during an individual''s development produces a lasting alteration in phenotype. Some instances of developmental plasticity may be adaptive, meaning that the tendency to produce the phenotype conditional on having experienced the developmental input has been under positive selection. We discuss the necessary assumptions and predictions of hypotheses concerning adaptive developmental plasticity (ADP) and develop guidelines for how to test empirically whether a particular example is adaptive. Central to our analysis is the distinction between two kinds of ADP: informational, where the developmental input provides information about the future environment, and somatic state-based, where the developmental input enduringly alters some aspect of the individual''s somatic state. Both types are likely to exist in nature, but evolve under different conditions. In all cases of ADP, the expected fitness of individuals who experience the input and develop the phenotype should be higher than that of those who experience the input and do not develop the phenotype, while the expected fitness of those who do not experience the input and do not develop the phenotype should be higher than those who do not experience the input and do develop the phenotype. We describe ancillary predictions that are specific to just one of the two types of ADP and thus distinguish between them.     

Simulated climate change: are passive greenhouses a valid microcosm for testing the biological effects of environmental perturbations?

This paper considers the use of passive greenhouse apparatus in field experiments investigating the biological consequences of climate change. The literature contains many accounts of such experiments claiming relevance of greenhouse treatment effects to global change scenarios. However, inadequacies in microclimate monitoring, together with incomplete understanding of greenhouse modes of action, cast doubt upon such claims. Here, treatment effects upon temperature (magnitude, range, variation, rates of change), moisture (humidity, precipitation, soil water content), light (intensity, spectral distribution), gas composition, snow cover, and wind speed are reviewed in the context of Intergovernmental Panel on Climate Change (IPCC) predictions. It is revealed that greenhouses modify each of these potentially limiting factors in a complex and interactive manner, but that the relationship between this modification and forecast conditions of climate change is poor. Interpretation of biological responses, and their extrapolation to predictive models, is thus unreliable. In order that future greenhouse experiments may overcome criticisms of artefact and lack of rigour, two amendments to methodology are proposed: (1) objective-orientated design of greenhouse apparatus (2) multiple controls addressing individual environmental factors. The importance of a priori testing of microclimate treatment effects is stressed.     

Adaptive response of Schizosaccharomyces pombe to hydrogen peroxide

Abstract Schizosaccharomyces pombe becomes resistant to killing by high concentration of hydrogen peroxide and other severe stresses including oxidants, high temperature and high concentration of ethanol when pretreated with nonlethal levels of hydrogen peroxide. In the presence of the protein synthesis inhibitor, cycloheximide, during hydrogen peroxide pretreatment, the cell obtained partial resistance to a higher level of hydrogen peroxide. The partial resistance to hydrogen peroxide in the presence of cycloheximide was acquired within 30 min of pretreatment but complete resistance obtained with de novo protein synthesis was not attained before 45 min of pretreatment. During adaptation to hydrogen peroxide, at least 15 polypeptides are induced, as analyzed by two-dimensional gel electrophoresis. Catalase activity is induced eight-fold by treatment with a nonlethal level of hydrogen peroxide.     

Oncogenic potential of Nrf2 and its principal target protein heme oxygenase-1

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential component of cellular defense against a vast variety of endogenous and exogenous insults, including oxidative stress. Nrf2 acts as a master switch in the circuits upregulating the expression of various stress-response proteins, especially heme oxygenase-1 (HO-1). Paradoxically, however, recent studies have demonstrated oncogenic functions of Nrf2 and its major target protein HO-1. Levels of Nrf2 and HO-1 are elevated in many different types of human malignancies, which may facilitate the remodeling of the tumor microenvironment making it advantageous for the autonomic growth of cancer cells, metastasis, angiogenesis, and tolerance to chemotherapeutic agents and radiation and photodynamic therapy. In this context, the cellular stress response or cytoprotective signaling mediated via the Nrf2–HO-1 axis is hijacked by cancer cells for their growth advantage and survival of anticancer treatment. Therefore, Nrf2 and HO-1 may represent potential therapeutic targets in the management of cancer. This review highlights the roles of Nrf2 and HO-1 in proliferation of cancer cells, their tolerance/resistance to anticancer treatments, and metastasis or angiogenesis in tumor progression.     

Construction of Saccharomyces cerevisiae strains that accumulate relatively low concentrations of trehalose, and their application in testing the contribution of the disaccharide to stress tolerance

Genetically related diploid strains of Saccharomyces cerevisiae that accumulate varied amounts of trehalose during starvation for nitrogen have been constructed. Strains that produced greater than 5% trehalose (dry cell weight) were more tolerant of thermal, or freeze-thaw stresses than strains that produced less than 4% trehalose. Thus trehalose appears to play a role in stress tolerance of yeast. The significance of these results is that, for the first time, a series of related, unmutated strains have been used to test the effect of trehalose on thermotolerance. Previous studies employed either heat shock treatment, or mutated strains to provide trehalose variations, and as such the contribution of the disaccharide to stress tolerance could not necessarily be separated from other factors such as heat shock proteins.