Mutation of cytotoxin-associated gene A affects expressions of antioxidant proteins of Helicobacter pylori

AIM: To determine if disruption of the cagA gene of Helicobacter pylori (H pylori) has an effect on the expression of other proteins at proteome level. METHODS: Construction of a cagA knock out mutant Hp27 _△cagA (cagA -) via homologous recombination with the wild-type strain Hp27 (cagA+) as a recipient was performed. The method of sonication-urea-CHAPS-DTT was employed to extract bacterial proteins from both strains. Soluble proteins were analyzed by two-dimensional electrophoresis (2-DE). Images of 2-DE gels were digitalized and analyzed. Only spots that had a statistical signif icance in differential expression were selected and analyzed by matrix-assisted laser desorption/ionizationtime of flight mass spectrometry (MALDI-TOF-MS). Biological information was used to search protein database and identify the biological function of proteins. RESULTS: The proteome expressions between wild-type strain and isogenic mutant with the cagA gene knocked-out were compared. Five protein spots with high abundance in bacteria proteins of wild-type strains, down-regulated or absently expressed in bacteria proteins of mutants, were identified and analyzed. From a quantitative point of view, the identified proteins are related to the cagA gene and important antioxidant proteins of H pylori , including alkyl hydroperoxide reductase (Ahp), superoxide dismutase (SOD) and modulator of drug activity (Mda66), respectively, suggesting that cagA is important to maintain the normal activity of antioxidative stress and ensure H pylori persistent colonization in the host. CONCLUSION: cagA gene is relevant to the expressions of antioxidant proteins of H pylori, which may be a novel mechanism involved in H pylori cagA pathogenesis.

Association between heat stress and oxidative stress in poultry;mitochondrial dysfunction and dietary interventions with phytochemicals

Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement of heat stress in inducing oxidative stress has received much interest. Oxidative stress is defined as the presence of reactive species in excess of the available antioxidant capacity of animal cells. Reactive species can modify several biologically cellular macromolecules and can interfere with cell signaling pathways. Furthermore, during the last decade, there has been an ever-increasing interest in the use of a wide array of natural feed-delivered phytochemicals that have potential antioxidant properties for poultry. In light of this, the current review aims to（1） summarize the mechanisms through which heat stress triggers excessive superoxide radical production in the mitochondrion and progresses into oxidative stress,（2） illustrate that this pathophysiology is dependent on the intensity and duration of heat stress,（3） present different nutritional strategies for mitigation of mitochondrial dysfunction, with particular focus on antioxidant phytochemicals.Oxidative stress that occurs with heat exposure can be manifest in all parts of the body; however, mitochondrial dysfunction underlies oxidative stress. In the initial phase of acute heat stress, mitochondrial substrate oxidation and electron transport chain activity are increased resulting in excessive superoxide production. During the later stage of acute heat stress, down-regulation of avian uncoupling protein worsens the oxidative stress situation causing mitochondrial dysfunction and tissue damage. Typically, antioxidant enzyme activities are upregulated. Chronic heat stress, however, leads to downsizing of mitochondrial metabolic oxidative capacity, up-regulation of avian uncoupling protein, a clear alteration in the pattern of antioxidant enzyme activities, and depletion of antioxidant reserves.Some phytochemicals, such as various types of flavonoids and related compounds, were shown to be beneficial in chronic heat-stressed poultry, but were less or not effective in non-heat-stressed counterparts. This supports the contention that antioxidant phytochemicals have potential under challenging conditions. Though substantial progress has been made in our understanding of the association between heat stress and oxidative stress, the means by which phytochemicals can alleviate oxidative stress have been sparsely explored.

Induction of Antioxidant and Heat Shock Protein Responses During Torpor in the Gray Mouse Lemur, Microcebus murinus

A natural tolerance of various environmental stresses is typically supported by various cytoprotective mechanisms that protect macromolecules and promote extended viability. Among these are antioxidant defenses that help to limit damage from reactive oxygen species and chaperones that help to minimize protein misfolding or unfolding under stress conditions. To understand the molecular mechanisms that act to protect cells during primate torpor, the present study characterizes antioxidant and heat shock protein（HSP） responses in various organs of control（aroused）and torpid gray mouse lemurs, Microcebus murinus. Protein expression of HSP70 and HSP90 a was elevated to 1.26 and 1.49 fold, respectively, in brown adipose tissue during torpor as compared with control animals, whereas HSP60 in liver of torpid animals was 1.15 fold of that in control（P 〈 0.05）. Among antioxidant enzymes, protein levels of thioredoxin 1 were elevated to 2.19 fold in white adipose tissue during torpor, whereas Cu–Zn superoxide dismutase 1 levels rose to 1.1 fold in skeletal muscle（P 〈 0.05）. Additionally, total antioxidant capacity was increased to 1.6 fold in liver during torpor（P 〈 0.05）, while remaining unchanged in the five other tissues. Overall, our data suggest that antioxidant and HSP responses are modified in a tissue-specific manner during daily torpor in gray mouse lemurs. Furthermore, our data also show that cytoprotective strategies employed during primate torpor are distinct from the strategies in rodent hibernation as reported in previous studies.