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.     

Antioxidant Defenses in the Brains of Bats during Hibernation

Hibernation is a strategy used by some mammals to survive a cold winter. Small hibernating mammals, such as squirrels and hamsters, use species- and tissue-specific antioxidant defenses to cope with oxidative insults during hibernation. Little is known about antioxidant responses and their regulatory mechanisms in hibernating bats. We found that the total level of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the brain of each of the two distantly related hibernating bats M. ricketti and R. ferrumequinum at arousal was lower than that at torpid or active state. We also found that the levels of malondialdehyde (product of lipid peroxidation) of the two hibernating species of bats were significantly lower than those of non-hibernating bats R. leschenaultia and C. sphinx. This observation suggests that bats maintain a basal level of ROS/RNS that does no harm to the brain during hibernation. Results of Western blotting showed that hibernating bats expressed higher amounts of antioxidant proteins than non-hibernating bats and that M. ricketti bats upregulated the expression of some enzymes to overcome oxidative stresses, such as superoxide dismutase, glutathione reductase, and catalase. In contrast, R. ferrumequinum bats maintained a relatively high level of superoxide dismutase 2, glutathione reductase, and thioredoxin-2 throughout the three different states of hibernation cycles. The levels of glutathione (GSH) were higher in M. ricketti bats than in R. ferrumequinum bats and were significantly elevated in R. ferrumequinum bats after torpor. These data suggest that M. ricketti bats use mainly antioxidant enzymes and R. ferrumequinum bats rely on both enzymes and low molecular weight antioxidants (e.g., glutathione) to avoid oxidative stresses during arousal. Furthermore, Nrf2 and FOXOs play major roles in the regulation of antioxidant defenses in the brains of bats during hibernation. Our study revealed strategies used by bats against oxidative insults during hibernation.     

PfeIK1, a eukaryotic initiation factor 2α kinase of the human malaria parasite Plasmodium falciparum, regulates stress-response to amino-acid starvation

Background

Plasmodium falciparum -parasitized red blood cells (RBCs) are equipped with protective antioxidant enzymes and heat shock proteins (HSPs). The latter are only considered to protect against thermal stress. Important issues are poorly explored: first, it is insufficiently known how both systems are expressed in relation to the parasite developmental stage; secondly, it is unknown whether P. falciparum HSPs are redox-responsive, in view of redox sensitivity of HSP in eukaryotic cells; thirdly, it is poorly known how the antioxidant defense machinery would respond to increased oxidative stress or inhibited antioxidant defense. Those issues are interesting as several antimalarials increase the oxidative stress or block antioxidant defense in the parasitized RBC. In addition, numerous inhibitors of HSPs are currently developed for cancer therapy and might be tested as anti-malarials. Thus, the joint disruption of the parasite antioxidant enzymes/HSP system would interfere with parasite growth and open new perspectives for anti-malaria therapy.

Methods

Stage-dependent mRNA expression of ten representative P. falciparum antioxidant enzymes and hsp 60/70–2/70–3/75/90 was studied by quantitative real-time RT-PCR in parasites growing in normal RBCs, in RBCs oxidatively-stressed by moderate H2O2 generation and in G6PD-deficient RBCs. Protein expression of antioxidant enzymes was assayed by Western blotting. The pentosephosphate-pathway flux was measured in isolated parasites after Sendai-virus lysis of RBC membrane.

Results

In parasites growing in normal RBCs, mRNA expression of antioxidant enzymes and HSPs displayed co-ordinated stage-dependent modulation, being low at ring, highest at early trophozoite and again very low at schizont stage. Additional exogenous oxidative stress or growth in antioxidant blunted G6PD-deficient RBCs indicated remarkable flexibility of both systems, manifested by enhanced, co-ordinated mRNA expression of antioxidant enzymes and HSPs. Protein expression of antioxidant enzymes was also increased in oxidatively-stressed trophozoites.

Conclusion

Results indicated that mRNA expression of parasite antioxidant enzymes and HSPs was co-ordinated and stage-dependent. Secondly, both systems were redox-responsive and showed remarkably increased and co-ordinated expression in oxidatively-stressed parasites and in parasites growing in antioxidant blunted G6PD-deficient RBCs. Lastly, as important anti-malarials either increase oxidant stress or impair antioxidant defense, results may encourage the inclusion of anti-HSP molecules in anti-malarial combined drugs.     

Environmental variability at the phosphoglucose isomerase locus in the genus Chlamys

Two geographically and reproductively isolated populations each of Chlamys opercularis and of Chlamys varia are compared with respect to polymorphism at the phosphoglucose isomerase (PGI) locus. One population of C. varia is further sub-divided into sub-littoral and inter-tidal samples. From the results it is inferred that PGI is a dimeric molecule, controlled by five alleles in C. varia and by at least four alleles in C. opercularis. acting at a single locus. The alleles recognised for C. opercularis have identical electrophoretic mobility as four of those seen in C. varia. The two populations of C. varia are remarkably similar, as were their habitats. However, the sub-littoral sample does show a lesser degree of homozygosity than the inter-tidal sample of the same population. The two populations of C. opercularis differ significantly and represent two separate and identifiable ‘races’. C. varia exhibits a much greater degree of genetic variability than the deep sub-littoral species, C. opercularis indicating that a more stable environment regulates a more monomorphic species.     

Seasonal variation in HSP70 expression and oxidative stress in skin of zebu (Tharparkar) and crossbred (Karan Fries) cattle under tropical climate

The study aimed to evaluate inducible HSP70 (HSP70.1 and HSP70.2) gene expression and oxidative stress status in skin of cattle during different seasons. Ten each of Tharparkar (zebu) and Karan Fries (crossbred) heifers were selected from NDRI herd, Karnal. Animals were maintained under standard managemental practices followed at the farm. Skin biopsies were aseptically collected from each animal during winter, spring, and summer. Real time PCR was performed to examine HSP70 expression. Reactive oxygen species (ROS) and antioxidant enzymes (SOD and CAT) were determined by ELISA. In both the breeds, significantly higher (p < 0.05) levels of HSP70 expression, ROS, caspases, and antioxidant enzymes were observed during summer followed by winter and spring. Breeds showed no significant difference during winter and spring. During summer, HSP70 expression, ROS, and antioxidant enzymes were higher (p < 0.05) in Karan Fries than Tharparkar, whereas caspases levels were higher in Tharparker than Karan Fries. The study concludes that levels of HSP70 expression, ROS, caspases, and antioxidant enzymes in skin of cattle were strongly affected by seasonal change in temperature. Differences exist in skin tissue thermotolerance of Tharparkar and Karan Fries cattle. This might be an efficient and centrally important mechanism for better adaptability of zebu cattle to heat stress.     

The role of the heat shock proteins (HSP70 and sHSP) in the thermotolerance of freshwater amphipods from contrasting habitats

The aim of this study was to clarify the significance of HSP70 and sHSP for thermotolerance in freshwater amphipods. We compared four amphipod species from different freshwater habitats and biogeographical regions (Central Europe vs. Lake Baikal). Test individuals were exposed to thermal stress generated by a water temperature of 25 °C. The thermotolerance of the species, determined by median lethal time (LT50), followed in decreasing order by Gmelinoides fasciatus, Echinogammarus berilloni, Gammarus pulex, Eulimnogammarus verrucosus. HSP70 and sHSP base level concentrations for the species were determined at control (i.e. non-stress) conditions. For HSP70, the base levels were positively correlated to the species' thermotolerances. For sHSP, however, only thermotolerant G. fasciatus showed a high level. Thermal stress at 25 °C water temperature caused a deferred onset of HSP70 and sHSP expression followed by a subsequent offset, delineating a unimodal response curve. The time lag to the expression onset of HSP70 was shorter in the thermosensitive species, compared to thermotolerant ones. Conversely, the time span until the maximum level of HSP70 was variable, not showing a dependence on the thermotolerance properties of the species. The peak concentration in G. pulex was distinctly higher than in the other species, whereas E. verrucosus did not develop a well-defined response maximum at all. In sHSP, the temporal pattern of expression was even more variable than in HSP70. However, the thermosensitive species E. verrucosus showed a time lag of expression onset significantly shorter than the other species and thermotolerant G. fasciatus developed the most pronounced response maximum. Basing on these results, the cellular response to thermal stress in amphipods is more consistently reflected by HSP70, compared to sHSP.     

Antioxidant status of Lobiger serradifalci and Oxynoe olivacea (Opisthobranchia, Mollusca)

Invasion of the Mediterranean Sea by the two world-wide famous exotic algae species, Caulerpa taxifolia and Caulerpa racemosa, is still a problem and has adverse effects on the Mediterranean sublittoral ecosystem. Biological control studies revealed that the two native Sacoglossans, Oxynoe olivacea and Lobiger serradifalci, may have an effect on the expansion of invasive Caulerpa spp. in the Mediterranean. In the framework of this study, antioxidant enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), lipid peroxidation (LPO) and oxidized glutathione (GSSG) levels, as oxidative stress markers in L. serradifalci and O. olivacea were determined at two different temperature conditions (20 and 27 °C). In both species, SOD, CAT and GSH-Px activities were found to be positively correlated with temperature. The SOD activities in L. serradifalci were higher than those in O. olivacea at both temperatures, whereas the CAT and GSH-Px activities were significantly (p<0.05) higher in O. olivacea, compared to L. serradifalci. As expected, both species showed decreased LPO levels at 27 °C compared to 20 °C. GSSG level at 27 °C in O.olivacea was significantly (p<0.05) higher than that of 20 °C. On the other hand, no statistical (p>0.05) difference in L.serradifalci existed between GSSG levels at two temperatures. But, despite the variations in the antioxidant enzyme activities, there was no significant difference in LPO levels between the species, suggesting that the oxidative consequences of a given environmental condition may vary among different species. Inasmuch as the GSSG levels were in accordance with antioxidant enzyme activities, GSH might have acted as a cofactor of GSH-Px and an individual antioxidant in these sea slugs.     

Variation of the Locomotor Activity Rhythms in Three Species of Talitrid Amphipods,Talitrus saltator,Orchestia montagui,and O. gammarellus,from Various Habitats

The expression of biological rhythms was investigated in five populations of three different species of talitrid amphipods from various habitats in the Maremma Regional Park, Grosseto, Italy: Talitrus saltator (from a sandy beach and a canal), Orchestia montagui (form a Posidonia banquette), and O. gammarellus (from a cave entrance and a river bank). Locomotor activity rhythms were recorded in individual animals over 21 days in constant dark at a temperature of 18°±1°C. A high variability in rhythm expression was evident, not only among species and populations but also within populations and the activity pattern of individuals. Activity rhythms of T. saltator and O. montagui were similar, with a good definition and precise circadian periodicity, whereas O. gammarellus showed a high variability and low definition of the circadian rhythm. Significant differences were also observed between two populations of O. gammarellus and T. saltator from different habitats. Within the O. gammarellus species, a significantly higher percentage of active animals (p<0.001) was observed in the cave than the river‐bank population; within T. saltator, a significantly lower percentage of active animals (p<0.01) and higher percentage of periodic animals (p<0.05) was found in the canal than the sandy beach population. With reference to environmental stability and variability, the differences observed are explained as a need for plasticity to adapt to environmental changes.     

Locomotor activity patterns of two sympatric species Orchestia montagui and Orchestia gammarellus (Crustacea,Amphipoda)

Freshly adult individuals of two sympatric species, Orchestia gammarellus and Orchestia montagui, collected in spring from the supralittoral zone of Bizerte lagoon (Northern of Tunisia) at Menzel Jemil, were housed in a controlled environment cabinet. Locomotor activity rhythm was recorded in isolated individuals and groups by infrared actograph every 20 min by a data-logger, at a constant temperature of 18 ± 0.5 °C under constant darkness. According to double-plotted actograms and waveform curves, results showed the presence of two different locomotor patterns; in fact, individuals of O. gammarellus concentrated their activity during the hours of subjective night, whereas O. montagui were active during the subjective night and beyond the subjective dawn. Furthermore, whatever the species studied, periodogram analysis indicated a distinct circadian pattern of activity. Moreover, whatever the experiment condition is, the most clearly defined rhythms were found in O. gammarellus. In contrary to O. gammarellus, the group effect on the locomotor rhythm parameters seems to be less marked in O. montagui. On the other hand, a highly inter-individual variability was observed in the activity time for these two species and especially for O. montagui groups.     

Oxidative stress induces distinct physiological responses in the two Trebouxia phycobionts of the lichen Ramalina farinacea

Background and Aims

Most lichens form associations with Trebouxia phycobionts and some of them simultaneously include genetically different algal lineages. In other symbiotic systems involving algae (e.g. reef corals), the relative abundances of different endosymbiotic algal clades may change over time. This process seems to provide a mechanism allowing the organism to respond to environmental stress. A similar mechanism may operate in lichens with more than one algal lineage, likewise protecting them against environmental stresses. Here, the physiological responses to oxidative stress of two distinct Trebouxia phycobionts (provisionally named TR1 and TR9) that coexist within the lichen Ramalina farinacea were analysed.

Methods

Isolated phycobionts were exposed to oxidative stress through the reactive oxygen species propagator cumene hydroperoxide (CuHP). Photosynthetic pigments and proteins, photosynthesis (through modulated chlorophyll fluorescence), the antioxidant enzymes superoxide dismutase (SOD) and glutathione reductase (GR), and the stress-related protein HSP70 were analysed.

Key Results

Photosynthetic performance was severely impaired by CuHP in phycobionts, as indicated by decreases in the maximal PSII photochemical efficiency (F_v/F_m), the quantum efficiency of PSII (Φ_PSII) and the non-photochemical dissipation of energy (NPQ). However, the CuHP-dependent decay in photosynthesis was significantly more severe in TR1, which also showed a lower NPQ and a reduced ability to preserve chlorophyll a, carotenoids and D1 protein. Additionally, differences were observed in the capacities of the two phycobionts to modulate antioxidant activities and HPS70 levels when exposed to oxidative stress. In TR1, CuHP significantly diminished HSP70 and GR but did not change SOD activities. In contrast, in TR9 the levels of both antioxidant enzymes and those of HSP70 increased in response to CuHP.

Conclusions

The better physiological performance of TR9 under oxidative conditions may reflect its greater capacity to undertake key metabolic adjustments, including increased non-photochemical quenching, higher antioxidant protection and the induction of repair mechanisms.     

Copper and zinc in an ecological series of talitroidean Amphipoda (Crustacea)

Summary Cu and Zn concentrations were determined for the following talitroidean amphipods, Hyale nilssoni (Rathke), Talitrus saltator (Montagu), Talorchestia deshayesii (Audouin), Orchestia mediterranea Costa, O. gammarellus (Pallas), O cavimana Heller and Arcitalitrus dorrieni (Hunt) in September 1986 from sites in W. Britain (mostly Scottish). To minimize size effects, only animals >2mg body dry weight were included in analyses. Only Talorchestia (Cu & Zn) and O. cavimana (Zn) showed any residual relationship between metal concentration and dry weight. Log transformed data for concentrations of each metal against log dry wt. in all species were compared by ANCOVA. Copper and zinc concentrations of males and females were not significantly different in O. gammarellus, O. mediterranea and T. deshayesii, though Cu (but not Zn) concentrations differed with sex in O. cavimana. The order of species when ranked according to an ascending series of Cu concentrations (at standard body weight) reflected their ecological zonation from sea to land closely, with species living proximal to the sea having lowest Cu concentrations. The 6 talitrid species all had similar Zn concentrations but the Zn concentration of H. nilssoni was considerably lower. There was a relationship between Cu and Zn concentrations in individuals of only one species (O. gammarellus). Data on Cu and Zn concentrations for O. gammarellus derived from the same site in September 1983 were almost exctly the same as in September 1986. The possible impact of seasonal variation on haemocyanin levels is discussed.     

Heat shock protein 70 regulates the abscisic acid-induced antioxidant response of maize to combined drought and heat stress

We investigated the interaction between heat shock protein 70 (HSP70) and abscisic acid (ABA)-induced antioxidant response of maize to the combination of drought and heat stress. First, the increased activities of enzymes, including superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT), induced by drought were less than those by heat or combined drought and heat stress, except some individual cases (e.g. CAT in leaves, GR in roots). Second, both HSP70 synthesis and H₂O₂ production increased prominently under drought, heat or their combination stress; the increase in leaves induced by drought and heat combination was the highest, followed by heat and by drought, while the increase in roots had not visible difference. Third, either in leaves or roots, pretreatment with ABA inhibitor, HSP70 inhibitor and H₂O₂ scavenger, significantly arrested the stress-induced increase of antioxidant enzyme activities, and ABA inhibitor and H₂O₂ scavenger obviously suppressed HSP70 synthesis, while HSP70 inhibitor slightly heightened H₂O₂ accumulation. Finally, 100 μM ABA significantly enhanced the activities of antioxidant enzymes, HSP70 expression and H₂O₂ production under stresses in comparison with ABA-deficient mutant vp5 maize plants without pretreatment. Thus, ABA-induced H₂O₂ production enhances the HSP70 synthesis and up-regulates the activities of antioxidant enzymes, resulting in the suppression of cellular reactive oxygen species (ROS) levels. Our results suggest that HSP70 may play a crucial role in ABA-induced antioxidant defense of maize to drought and heat combination.     

Genome-wide identification and characterization of HSP70 gene family in four species of cotton

Heat shock proteins (HSPs) are important elements of the cellular group of molecular chaperones. Specifically, HSP70 proteins protect cells from being damaged when plants are exposed to environmental stresses. These proteins are catalysts that manage the correct folding of other proteins, and they play a key role in the development of tolerance against biotic and abiotic stresses. In the present study, 113 HSP70 genes were retrieved from the available genome assemblies of four cotton species, including Gossypium hirsutum, G. barbadense, G. arboreum, and G. raimondii. The HSP70 genes were clustered into 11 subfamilies based on phylogeny. One hundred and nine (109) gene duplications were found across these four species. Localization of genes revealed that several HSP70 genes reside in the cytoplasm. Synonymous and non-synonymous substitution rates revealed that functional segregation of HSP70 genes in cotton is due to purifying selection. Furthermore, HSP70 genes in cotton are expressed constitutively during developmental stages. These findings are valuable to understand the complex mechanism of HSP70 gene regulation that occurs in signaling pathways in response to plant stress.     

Evaporative water loss under desiccation stress in semiterrestrial and terrestrial amphipods (Crustacea: Amphipoda: Talitridae)

Transpiration rates were measured in both still and moving air systems in three talitrid amphipods, Orchestia gammarellus (Pallas), Talitrus saltator (Montagu), and Arcitalitrus dorrieni (Hunt). Significant differences were demonstrated between the rates of water loss in the three species. The terrestrial A. dorrieni exhibited much higher rates than the supralittoral species. In still air at 15 °C and 75% r.h., for example, the mean rate in A. dorrieni was 0.183 ± 0.008 mg·h⁻¹· mg wet wt⁻¹ compared with 0.111 ± 0.003 for Orchestia gammarellus and 0.106 ± 0.003 for Talitrus saltator. In moving air, regression lines plotting weight-specific rates of water loss against saturation deficit were significantly different between the three species in their slope. The regression line for Arcitalitrus dorrieni (R= - 0.0514 + 0.0481φ) was much steeper than that for Orchestia gammarellus (R = 0.0465 + 0.0187φ) and for Talitrus saltator (R = 0.033 + 0.0128φ).Arcitalitrus dorrieni therefore showed the highest rates ofwater loss, under conditions of high desiccation stress, but there was no clear difference between the species at low values of saturation deficit. Mean calculated permeabilities reflect this trend: A. dorrieni, 0.0403 ± 0.0009 mg · h⁻¹· mg wet wt⁻¹ · mm Hg⁻¹, Orchestia gammarellus, 0.0247 ± 0.0008, and Talitrus saltator, 0.0188 − 0.0006. Juvenile supralittoral talitrids of approximately the same body size as Arcitalitrus dorrieni consistently showed higher weight-specific rates of water loss in still air than adults of their own species, but the rates were usually lower than those of adult A. dorrieni. The very high rates of transpiration in A. dorrieni are not explicable by purely allometric considerations. The results are discussed with reference to the ecology and natural habitats of the species investigated and in relation to the colonization of the terrestrial habitat.     

Antioxidant Enzymes in Phytoparasitic Nematodes

Presence of different antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and ascorbate, p-phenilendiamine-pyrocathecol (PPD-PC), o-dianisidine, and guaiacol isoperoxidases, was shown in the phytoparasific nematode species Meloidogyne incognita, M. hapla, Globodera rostochiensis, G. pallida, Heterodera schachtii, H. carotae, and Xiphinema index. The activity of the enzymes tested differed among the life stages examined. SOD was present in cysts but was not detected in Meloidogyne egg masses. Catalase activity of Meloidogyne females was higher than that of preparasitic stages and cyst-nematode females. For the first time, ascorbate peroxidase was found to occur commonly in phytoparasitic nematodes, with the highest activity in the invading life-stages. In all the life stages examined, the antioxidant enzyme activities of M. hapla were markedly higher than those of M. incognita. Glutathione peroxidase was not found in the species examined.     

Seasonal variation in copper and zinc concentrations in three talitrid amphipods (Crustacea)

Cu and Zn concentrations were determined for three talitrid amphipods, Orchestia gammarellus (Pallas), O. mediterranea Costa and Talitrus saltator (Montagu), collected at two-monthly intervals in 1987 from sites on Great Cumbrae Island, Firth of Clyde, Scotland. To account for size effects, log transformed Cu and Zn concentrations were regressed against log dry weight for each bimonthly sample of each species, and compared by analysis of covariance. Copper concentrations in O. gammarellus were significantly raised in March 1987, and lowered in November 1987. Copper concentrations in O. mediterranea and T. saltator were significantly lowered in November 1987. Cu concentrations differed interspecifically in the order O. gammarellus > O. mediterranea > T. saltator. There was no significant intraspecific seasonal variation in zinc concentration in any of the three species. Zn concentrations differed interspecifically in the order T. saltator > O. gammarellus > O. mediterranea.     

Quantitative Proteomic Analysis Reveals Important Roles of the Acetylation of ER-Resident Molecular Chaperones for Conidiation in Fusarium oxysporum

Fusarium oxysporum is one of the most abundant and diverse fungal species found in soils and includes nonpathogenic, endophytic, and pathogenic strains affecting a broad range of plant and animal hosts. Conidiation is the major mode of reproduction in many filamentous fungi, but the regulation of this process is largely unknown. Lysine acetylation (Kac) is an evolutionarily conserved and widespread posttranslational modification implicated in regulation of multiple metabolic processes. A total of 62 upregulated and 49 downregulated Kac proteins were identified in sporulating mycelia versus nonsporulating mycelia of F. oxysporum. Diverse cellular proteins, including glycolytic enzymes, ribosomal proteins, and endoplasmic reticulum–resident molecular chaperones, were differentially acetylated in the sporulation process. Altered Kac levels of three endoplasmic reticulum–resident molecular chaperones, PDI^K70, HSP70^K604, and HSP40^K32 were identified that with important roles in F. oxysporum conidiation. Specifically, K70 acetylation (K70ac) was found to be crucial for maintaining stability and activity of protein disulphide isomerase and the K604ac of HSP70 and K32ac of HSP40 suppressed the detoxification ability of these heat shock proteins, resulting in higher levels of protein aggregation. During conidial formation, an increased level of PDI^K70ac and decreased levels of HSP70^K604ac and HSP40^K32ac contributed to the proper processing of unfolded proteins and eliminated protein aggregation, which is beneficial for dramatic cell biological remodeling during conidiation in F. oxysporum.     

Age-related changes in antioxidant enzyme activities, fatty acid composition and lipid peroxidation in whole body Gammarus locusta (Crustacea: Amphipoda)

The main aim of this work was to provide baseline data on aspects of pro-oxidant and antioxidant processes in different life-stages of the marine amphipod Gammarus locusta. The activities of antioxidant enzymes and levels of lipid peroxidation were determined in whole body juveniles, subadults, and male and female adults of a laboratory population of G. locusta. Fatty acid composition of individuals at these different stages of development was also characterised in order to examine the contribution that polyunsaturated fatty acids (PUFA) might make to the peroxidation status of animals. The antioxidant enzymes, measured in whole body 100,000 supernatants, comprised catalase (CAT, EC 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1) and glutathione peroxidase (GPX; EC 1.11.1.9). Fatty acids were analysed as fatty acid methyl esters (FAME). Lipid peroxidation was examined in terms of the levels of lipid peroxides determined as thiobarbituric acid-reactive malondialdehyde equivalents. Age-related changes were seen in antioxidant enzyme status: levels of SOD (p<0.01) and GPX (p<0.001) activities decreased progressively during development from juveniles to adults. Sex-related changes in GPX activity were also seen, the levels being higher in adult males than females (p<0.001). The amount of FAME present in whole body amphipod also changed over the life span. Among PUFA, the eicosapentaenoic (C20:5n-3), arachidonic (C20:4n-6) and docosahexaenoic (C22:6n-3) were the most abundant acids in this species, and both their individual concentrations and total PUFA increased progressively with age (up to 3.3-fold; p<0.001). The latter changes may contribute to the explanation of the observed differences in peroxidation status of the animals with age; thus, levels of lipid peroxides increased up to 40% in adult males compared to other age-classes (p<0.01). Overall, the decline in antioxidant enzyme activities, coupled with increased levels of PUFA, as the individual grows older, may render the older animals more susceptible to lipid peroxidation and oxidative stress.