Cu,Zn superoxide dismutase genes in Tribolium castaneum: evolution, molecular characterisation and gene expression during immune priming.

The production of reactive oxygen species (ROS) is a normal consequence of the aerobic cell metabolism. Despite their high and potentially detrimental reactivity with various biomolecules, the endogenous production of ROS is a vital part of physiological, immunological, and molecular processes that contribute to fitness. The role of ROS in host\u2013parasite interactions is frequently defined by their contribution to innate immunity as effectors, promoting parasite death during infections. In vertebrates, ROS and antioxidant system enzymes, such as superoxide dismutase (SOD) are also involved in acquired immune memory, where they are responsible for T-cell signalling, activation, proliferation, and viability. Based on recent findings, ROS are now also assumed to play a role in immune priming, i.e., a form of memory in invertebrates. In this study, the potential involvement of Cu,Zn SODs in immunity of the red flour beetle Tribolium castaneum is described for the first time, applying an approach that combines an in\ua0silico gene characterisation with an in\ua0vivo immune priming experiment using the Gram-positive entomopathogen Bacillus thuringiensis. We identified an unusually high number of three different transcripts for extracellular SOD and found that priming leads to a fine-tuned modulation of SOD expression, highlighting the potential of physiological co-adaptations for immune phenotypes

Longevity Genes: From Primitive Organisms to Humans

A variety of lines of evidence indicate that aging and longevity are subject to genetic regulation, but until fairly recently the identity of these genes was unknown. This has changed dramatically over the last ten years. Recommends several courses of carrying research on "longevity genes" to humans

Transcriptional profiling of MnSOD-mediated lifespan extension in Drosophila reveals a species-general network of aging and metabolic genes.

BACKGROUND: Several interventions increase lifespan in model organisms, including reduced insulin/insulin-like growth factor-like signaling (IIS), FOXO transcription factor activation, dietary restriction, and superoxide dismutase (SOD) over-expression. One question is whether these manipulations function through different mechanisms, or whether they intersect on common processes affecting aging. RESULTS: A doxycycline-regulated system was used to over-express manganese-SOD (MnSOD) in adult Drosophila, yielding increases in mean and maximal lifespan of 20%. Increased lifespan resulted from lowered initial mortality rate and required MnSOD over-expression in the adult. Transcriptional profiling indicated that the expression of specific genes was altered by MnSOD in a manner opposite to their pattern during normal aging, revealing a set of candidate biomarkers of aging enriched for carbohydrate metabolism and electron transport genes and suggesting a true delay in physiological aging, rather than a novel phenotype. Strikingly, cross-dataset comparisons indicated that the pattern of gene expression caused by MnSOD was similar to that observed in long-lived Caenorhabditis elegans insulin-like signaling mutants and to the xenobiotic stress response, thus exposing potential conserved longevity promoting genes and implicating detoxification in Drosophila longevity. CONCLUSION: The data suggest that MnSOD up-regulation and a retrograde signal of reactive oxygen species from the mitochondria normally function as an intermediate step in the extension of lifespan caused by reduced insulin-like signaling in various species. The results implicate a species-conserved net of coordinated genes that affect the rate of senescence by modulating energetic efficiency, purine biosynthesis, apoptotic pathways, endocrine signals, and the detoxification and excretion of metabolites.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Understanding ageing - the role of mitochondria in determination of caenorhabditis elegans life span

Mitochondria are organelles found in eukaryotic cells. They are involved in many vital cellular functions. Consequently, mitochondrial dysfunction leads to a variety of human disorders. Many studies of the last 50 years showed that mitochondria are involved in the regulation of physiological ageing. However, the underlying mechanisms are still unknown. We aimed to analyze the mitochondrial role in ageing in Caenorhabditis elegans model system. Its short life cycle, powerful genetic tools and known fates of all 959 post-mitotic somatic cells make this nematode an excellent model system for ageing studies. Besides numerous advantages, the small body size of the worm brings along certain technical limitations. We developed a toolkit to analyze mitochondrial morphology, metabolic profile and electron transport chain (ETC) activities on a single-tissue level. In addition, we adapted a method for analysis of mtDNA copy number for use on individual animals. Each mitochondrion has its own genome that is maintained by mitochondrial DNA polymerase gamma (POLG). By analyzing polg-1 mutant worms that are deficient in the sole mitochondrial DNA polymerase, we showed that C. elegans mtDNA replication mainly takes place in the gonad, the only proliferative tissue in adult worms. Thus mtDNA depletion leads to marked dysfunction of this organ. Severe mtDNA depletion leads to embryonic arrest, whereas mild depletion does not affect development. We showed that mtDNA replication does not take place during embryogenesis; it starts during the L3 larval stage, correlating with germline proliferation. Taken together, mtDNA copies in the somatic tissues mainly stem from the oocyte and stay relatively unchanged during development and early adulthood. Remarkably, somatic tissues are not severely affected in polg-1 deficient animals despite the marked overall mtDNA depletion in contrast to other model systems, namely flies and mice. Furthermore, we showed that mtDNA copy number exhibits substantial plasticity upon environmental stress. Mitochondria are the major source of ATP, which they form by oxidative phosphorylation (OXPHOS). Defective OXPHOS often results in severe phenotypes or premature death in several animal models. However, studies in C. elegans showed that dysfunction in the mitochondrial respiratory chain is not necessarily lethal. It can rather result in lifespan prolongation in the so-called “Mit mitochondrial) mutants”. We analyzed molecular mechanisms that underlie the longevity induced by mitochondrial dysfunction. It has been shown that different mechanisms can affect the longevity of Mit mutants. We found that succinate dehydrogenase activity of electron transport chain (ETC) complex II (CII) influences the lifespan of Mit mutants independently of the insulin-like/IGF-1 pathway. We showed that mitochondrial unfolding protein response (UPRmt) is up-regulated in both short- and long-lived Mit mutants. Furthermore, our results suggest that respiration rate is not necessarily linked to longevity. Analysis of several metabolic pathways in Mit mutants revealed that dysfunction of the mitochondrial respiratory chain leads to a common response characterized by up-regulation of the citric acid cycle, glycolysis, and some anaerobic pathways, accompanied by increase in neutral fat storage

Evaluating the effects of oxidative stress on microRNA accumulation in Drosophila melanogaster and their regulatory roles in cellular protection and degeneration

Oxidative stress is considered to be an underlying mechanism in the pathogenesis of many cellular degenerative processes. In this study, microRNAs (miRNAs) are examined as potential epigenetic regulators of the oxidative stress response. In an effort to identify miRNAs up- or down-regulated during oxidative stress, we conducted a microarray analysis to evaluate miRNA accumulation changes in Drosophila melanogaster exposed to hyperoxic versus normoxic conditions. Several miRNAs were further evaluated using qRT-PCR to determine their accumulation in whole bodies and heads as well as changes over extended hyperoxia exposures. Dme-miR-8, -11, and -970 were found to be up-regulated in both whole bodies and heads after 5 days hyperoxia exposure. Jaguar (jag), castor (cas), and derailed (drl) were identified as putative targets of these three miRNAs using miRNA target prediction algorithms. Reporter gene-based assays were used to examine the interaction of the miRNAs with the target mRNAs, and confirmed functional suppressive relationships between miR-11:cas and miR-970:drl, but not miR-8:jag. Cell-based assays were also used to assess the ability of candidate microRNAs to suppress expression of several different predicted target genes with known antioxidant activities: superoxide dismutase (Sod), heat shock protein cognate70-4 (Hsc70-4), sniffer (sni), thioredoxin-2 (trx-2), and catalase (cat). Sod was not significantly down-regulated by any miRNA, but mir-927:Hsc70-4, mir-964:Hsc70-4, mir-277:sni, mir-1013:trx-2, and mir-1012:cat interactions were all functionally verified in addition to some pairings having correlational accumulation/expression profiles under hyperoxic stress conditions.February 201

Multilocus patterns of nucleotide variability and the demographic and selection history of drosophila melanogaster populations

Uncertainty about the demographic history of populations can hamper genome-wide scans for selection based on population genetic models. To obtain a portrait of the effects of demographic history on genome variability patterns in Drosophila melanogaster populations, we surveyed noncoding DNA polymorphism at 10 X-linked loci in large samples from three African and two non-African populations. All five populations show significant departures from expectations under the standard neutral model. We detect weak but significant differentiation between East (Kenya and Zimbabwe) and West/Central sub-Saharan (Gabon) African populations. A skew toward high-frequency-derived polymorphisms, elevated levels of linkage disequilibrium (LD) and significant heterogeneity in levels of polymorphism and divergence in the Gabon sample suggest that this population is further from mutation-drift equilibrium than the two Eastern African populations. Both non-African populations harbor significantly higher levels of LD, a large excess of high-frequency-derived mutations and extreme heterogeneity among loci in levels of polymorphism and divergence. Rejections of the neutral model in D. melanogaster populations using these and similar features have been interpreted as evidence for an important role for natural selection in shaping genome variability patterns. Based on simulations, we conclude that simple bottleneck models are sufficient to account for most, if not all, polymorphism features of both African and non-African populations. In contrast, we show that a steady-state recurrent hitchhiking model fails to account for several aspects of the data. Demographic departures from equilibrium expectations in both ancestral and derived populations thus represent a serious challenge to detecting positive selection in genome-wide scans using current methodologies

Alopecia areata: a multifactorial autoimmune condition

Alopecia areata is an autoimmune disease that results in non-scarring hair loss, and it is clinically characterised by small patches of baldness on the scalp and/or around the body. It can later progress to total loss of scalp hair (Alopecia totalis) and/or total loss of all body hair (Alopecia universalis). The rapid rate of hair loss and disfiguration caused by the condition causes anxiety on patients and increases the risks of developing psychological and psychiatric complications. Hair loss in alopecia areata is caused by lymphocytic infiltrations around the hair follicles and IFN-γ. IgG antibodies against the hair follicle cells are also found in alopecia areata sufferers. In addition, the disease coexists with other autoimmune disorders and can come secondary to infections or inflammation. However, despite the growing knowledge about alopecia areata, the aetiology and pathophysiology of disease are not well defined. In this review we discuss various genetic and environmental factors that cause autoimmunity and describe the immune mechanisms that lead to hair loss in alopecia areata patients

A common theme in extracellular fluids of beetles: extracellular superoxide dismutases crucial for balancing ROS in response to microbial challenge

Extracellular Cu/Zn superoxide dismutases (SODs) are critical for balancing the level of reactive oxygen species in the extracellular matrix of eukaryotes. In the present study we have detected constitutive SOD activity in the haemolymph and defensive secretions of different leaf beetle species. Exemplarily, we have chosen the mustard leaf beetle, Phaedon cochleariae, as representative model organism to investigate the role of extracellular SODs in antimicrobial defence. Qualitative and quantitative proteome analyses resulted in the identification of two extracellular Cu/Zn SODs in the haemolymph and one in the defensive secretions of juvenile P. cochleariae. Furthermore, quantitative expression studies indicated fat body tissue and defensive glands as the main synthesis sites of these SODs. Silencing of the two SODs revealed one of them, PcSOD3.1, as the only relevant enzyme facilitating SOD activity in haemolymph and defensive secretions in vivo. Upon challenge with the entomopathogenic fungus, Metarhizium anisopliae, PcSOD3.1-deficient larvae exhibited a significantly higher mortality compared to other SOD-silenced groups. Hence, our results serve as a basis for further research on SOD regulated host-pathogen interactions. In defensive secretions PcSOD3.1-silencing affected neither deterrent production nor activity against fungal growth. Instead, we propose another antifungal mechanism based on MRJP/yellow proteins in the defensive exudates

Evaluation of the activity of the immune system and age-related tissue markers in Turquoise killifish \ud (Nothobranchius furzeri, Jubb 1971) \ud and their role in cell ageing\ud

Currently the Turquoise Killifish is considered the best animal model suitable for aging research. \ud This annual fish, from south east Africa, shows an exceptionally adaptive behaviour to dry periods: indeed, due to this extreme environmental characteristics, the life cycle of Nothobranchius furzeri is very fast, with an average lifespan of just about 8-9 weeks, making this species (more similar to highly developed vertebrates than nematodes or fruit flies) highly practical for aging studies. \ud The present study has evaluated the activity of the immune system as well as the expression of AGE-RAGE system, cell-damage related proteins (Bcl2, p53), mitosis activity marker (PCNA), and pro-apoptosis activity by T.U.N.E.L. method on the liver of four lifespan-specific strains of Turquoise Killifish (Nothobranchius furzeri, Jubb 1971), correlating the results with aging processes and tumor incidence. Some groups underwent caloric restriction in order to module their expected lifespan.\ud The results demonstrated an increase of age-related lesions along with the age in all the strains tested, due to a decrease of cellular-turn-over. This aspect was also influenced by the strain of the fish: longest lifespan strains showed later the similar lesions than short lifespan strains. Moreover caloric restriction groups showed lower incidence and severity of hepatic degeneration than control groups. Furthermore, there was a linear correspondence between the age of the model and its expected lifespan with the incidence and severity of neoplasm. The same relationship could be found in the expression of cell-damage related proteins (p53, Bcl2), age-related markers (AGE-RAGE system) and pro-apoptosis activity, as well as in the development of neoplasms. These results demonstrated the high feasibility of this fish as an excellent model to study the effects of aging processes and cancer genesis.\u