The dose-dependent effect of 3,5-dicarbomethoxyphenylbiguanide on activity of the glutathione antioxidant system in heart and blood serum of rats with experimental myocardial infarction

Administration of a synthetic compound with predicted anti-ischemic and cardioprotective activity, 3,5-dicarbomethoxyphenylbiguanide (3,5-DCMPBG) to rats with experimental myocardial infarction led to a decrease in the lipid peroxidation level, glutathione peroxidase activity, the level of reduced glutathione, activity of NADP-isocitrate dehydrogenase in the heart and blood serum, and activity of glucoso-6-phosphate dehydrogenase in heart in comparison with their levels in untreated animals with myocardial infarction. This may be attributed to a decrease of free radical processes and reduction of antioxidant system loading induced by the protective effect of the administered compound. At the same time the increase glutathione reductase activity observed under these conditions in the heart and blood serum is probably associated with specific influence of 3,5-DCMPBG on this enzyme.     

An experimental test on time constraint and sexual conflict over parental care

Because parental care is costly, a sexual conflict between parents over parental investment is expected to arise. Parental care behavior is an adaptive decision, involving trade‐offs between remating, and consequently desertion of the brood, and continuing parental effort. If the main advantage of desertion is remating, then this will be a time constraint, because the deserting individual will require a certain minimum period of time to breed again in the same breeding season. So, a short breeding season should force certain individuals to desert the first brood to have enough time to successfully complete their second breeding attempt. The rock sparrow, Petronia petronia, is an unusual species in which brood desertion can occur in both sexes and the breeding season is quite short so it is a good species to investigate the role of time constraint on brood desertion. For 3 years, I investigated the brood desertion modality of the rock sparrow. Then, for 2 years, I removed a group of experimental nest boxes during the autumn. Later, I re‐installed the experimental nest boxes after the start of the breeding season (2 weeks after the first egg was laid), mimicking a shortening of the breeding season for the (experimental) pairs that used experimental nest boxes. I found that in the experimental pairs, the percentage of deserting individuals was significantly higher than in the control groups, and the deserting individuals were older females. This experiment adds to our knowledge of timing of reproduction effects on individual decisions to desert by showing that a short and delayed breeding season may have different effects on males and females. To my knowledge, this is the first experimental study that demonstrates a direct link between time constraint and brood desertion.     

Effects of carotenoids, immune activation and immune suppression on the intensity of chronic coccidiosis in greenfinches

Allocation trade-offs of carotenoids between their use in the immune system and production of integumentary colouration have been suggested as a proximate mechanism maintaining honesty of signal traits. We tested how dietary carotenoid supplementation, immune activation and immune suppression affect intensity of coccidian infection in captive greenfinches Carduelis chloris, a passerine with carotenoid-based plumage. Immune activation with phytohaemagglutinin (PHA) decreased body mass among birds not supplemented with lutein, while among the carotenoid-fed birds, PHA had no effect on mass dynamics. Immune suppression with dexamethasone (DEX) induced loss of body mass and reduced the swelling response to PHA. DEX and PHA increased the concentration of circulating heterophils. Lutein supplementation increased plasma carotenoid levels but had no effect on the swelling response induced by PHA. PHA and DEX treatments did not affect plasma carotenoids. Immune stimulation by PHA suppressed the infection, but only among carotenoid-supplemented birds. Priming of the immune system can thus aid in suppressing chronic infection but only when sufficient amount of carotenoids is available. Our experiment shows the importance of carotenoids in immune response, but also the complicated nature of this impact, which could be the reason for inconsistent results in studies investigating the immunomodulatory effects of carotenoids. The findings about involvement of carotenoids in modulation of an immune response against coccidiosis suggest that carotenoid-based ornaments may honestly signal individuals’ ability to manage chronic infections.     

An experimental test of the contributions and condition dependence of microstructure and carotenoids in yellow plumage coloration

A combination of structural and pigmentary components is responsible for many of the colour displays of animals. Despite the ubiquity of this type of coloration, neither the relative contribution of structures and pigments to variation in such colour displays nor the relative effects of extrinsic factors on the structural and pigment-based components of such colour has been determined. Understanding the sources of colour variation is important because structures and pigments may convey different information to conspecifics. In an experiment on captive American goldfinches Carduelis tristis, we manipulated two parameters, carotenoid availability and food availability, known to affect the expression of carotenoid pigments in a full-factorial design. Yellow feathers from these birds were then analysed in two ways. First, we used full-spectrum spectrometry and high-performance liquid chromatography to examine the extent to which variation in white structural colour and total carotenoid content was associated with variation in colour properties of feathers. The carotenoid content of yellow feathers predicted two colour parameters (principal component 1--representing high values of ultraviolet and yellow chroma and low values of violet-blue chroma-and hue). Two different colour parameters (violet-blue and yellow chroma) from white de-pigmented feathers, as well as carotenoid content, predicted reflectance measurements from yellow feathers. Second, we determined the relative effects of our experimental manipulations on white structural colour and yellow colour. Carotenoid availability directly affected yellow colour, while food availability affected it only in combination with carotenoid availability. None of our manipulations had significant effects on the expression of white structural colour. Our results suggest that the contribution of microstructures to variation in the expression of yellow coloration is less than the contribution of carotenoid content, and that carotenoid deposition is more dependent on extrinsic variability than is the production of white structural colour.     

Study on the wall-breaking method of carotenoids producing yeast Sporidiobolus pararoseus and the antioxidant effect of four carotenoids on SK-HEP-1 cells

Abstract

The cell wall of carotenoids producing yeast Sporidiobolus pararoseus was broken through five different methods: acid-heating method, dimethyl sulfoxide (DMSO) method, enzymatic method, high-pressure homogenization (HPH) method, and cell autolysis method. HPH method not only brought the optimum breaking effect (wall-breaking extent of 72.3%) and the highest carotenoid extraction rate (67.2%), but also had the advantages of short-time, simple process, safe, and pollution-free. After optimization, the wall-breaking extent and the carotenoid extraction rate were enhanced to 78.3% and 82.5%, respectively. And the optimum conditions of HPH were obtained as homogenization pressure 80?MPa, bacterial liquid concentration 8% and homogenization for three times. Moreover, cell experiments demonstrated that all of the four carotenoids (β-carotene, γ-carotene, torulene, and torularhodin) purified from intracellular products of S. pararoseus. had the effect of resistance to oxidative damage from hydrogen peroxide on SK-HEP-1 cells, and torulene showed the most notable effect among them.     

In vivo antioxidant activity of carotenoids from Dunaliella salina--a green microalga

Dunaliella salina a green marine alga is known for its carotenoid accumulation, having various applications in the health and nutritional products. The purpose of present study was to evaluate the ability of D. salina algal powder extract to protect against oxidative stress In vivo using animal models. Treatment of albino Wistar strain rats with 125 microg/kg and 250 microg/kg b.w. showed significant protection when compared to toxin treated (CCl4) group. Since beta-carotene is major constituent of Dunaliella the results were also compared with group treated with 250 microg/kg b.w (p.o.) synthetic all trans beta-carotene. Treatment of CCl4 at dose of 2.0 g/kg b.w. decreased the activities of various antioxidant enzymes like catalase, superoxide dismutase (SOD) and peroxidase by 45.9%, 56% and 54% respectively compared to control group and lipid peroxidation value increased nearly 2 folds. Pretreatment of rats with 125 microg carotenoid followed by CCl4 treatment caused restoration of catalase, SOD and peroxidase by 25.24%, 23.75 and 61.15% respectively as compared to control. The group treated with 250 microg/kg has shown the restoration of 53.5%, 57.7 and 90.64% of catalase, SOD and peroxidase, respectively. This group has shown 75.0% restoration of peroxidation compared to control group of animals. The above enzyme activities were not significantly restored in group treated with synthetic all trans beta-carotene, which showed 7.5%, 23.8% restore in catalase and peroxidase content. The level of superoxide dismutase remained same and lipid peroxidation value decreased only by 23% in synthetic all trans beta-carotene treated group in comparison with control group. These results clearly indicate the beneficial effect of algal carotenoid compared to synthetic carotene as antioxidant. Owing to this property, the algae Dunaliella can be further extended to exploit, its possible application for various health benefits as nutraceuticals and food additive.     

An experimental test of the effect of plant functional group diversity on arthropod diversity

Characteristics used to categorize plant species into functional groups for their effects on ecosystem functioning may also be relevant to higher trophic levels. In addition, plant and consumer diversity should be positively related because more diverse plant communities offer a greater variety of resources for the consumers. Thus, the functional group composition and richness of a plant community may affect the composition and diversity of the herbivores and even higher trophic levels associated with that community. We tested this hypothesis by sampling arthropods with a vacuum sampler (34 531 individuals of 494 species) from an experiment in which we manipulated plant functional group richness and composition. Plant manipulations included all combinations of three functional groups (forbs, C₃ graminoids, and C₄ graminoids) removed zero, one, or two at a time from grassland plots at Cedar Creek Natural History Area, MN. Although total arthropod species richness was unrelated to plant functional group richness or composition, the species richness of some arthropod orders was affected by plant functional group composition. Two plant characteristics explained most of the effects of plant functional groups on arthropod species richness. Nutritional quality, a characteristic related to ecosystem functioning, and taxonomic diversity, a characteristic not used to designate plant functional groups, seemed to affect arthropod species richness both directly and indirectly. Thus, plant functional groups designated for their effects on ecosystem processes will only be partially relevant to consumer diversity and abundance.     

An experimental test of the discreteness-of-charge effect in positive and negative lipid bilayers

The electrostatic properties of charged bilayers and the bilayer component of biological membranes are often described theoretically by assuming the charge is smeared uniformly over the surface. This is one of the fundamental assumptions in the Gouy-Chapman-Stern (GCS) theory. However, the average distance between the charged phospholipids in a typical biological membrane is 2-3 nm, which is 2-3 times the Debye length in a 0.1 M salt solution. Existing discreteness-of-charge theories predict significant deviations from the GCS theory for the adsorption of ions to such membranes. We considered the predictions of the simplest discreteness-of-charge theory [Nelson, A. P., & McQuarrie, D. A. (1975) J. Theor. Biol. 55, 13-27], in which the charges are assumed to be fixed in a square lattice and the potential is described by the linearized Poisson-Boltzmann relation. This theory predicts deviations that are larger for counterions than for co-ions and much larger for divalent than for monovalent counterions. We tested these predictions by measuring the adsorption of a fluorescent monovalent anion and a paramagnetic divalent cation to both positive and negative membranes, which we demonstrated experimentally had the same average surface potential. All our experimental results with probes, including those obtained on membranes in the gel rather than in the liquid-crystalline state, agreed with the predictions of the GCS theory rather than with the discreteness-of-charge theory. A simple calculation indicates that the agreement between the experimental results and the predictions of the GCS theory could be due to the finite size of the lipids.     

The role of labile complexes with oxygen in antioxidant activity of carotenoids

The present research work was done with the main purpose to study early stages of interaction of carotenoids (Car) with molecular oxygen and clarify their role in the mechanism responsible for Car radiochemical stability and carotenoid ability to decrease concentration of the most active oxygen transients like superoxide anion radicals (O2.-). Alcoholic and phosphate buffer (pH 7.5) solutions of carotenoid fucoxanthin (Fx) were used for investigation of the oxygen effect on the absorption spectra in the UV-Visible range. Special analysis of time dependent reversible shifts of absorption bands of evacuated Fx solution after contact with O2 indicated existence of equilibrium between two distinct forms of Car: Fx and the labile charge transfer complex (Fx+delta...O2-delta). The velocity of the achievement of equilibrium state and a degree of reversibility depend on chemical structure of the carotenoid, oxygen content and the solvent nature. Radiation-chemical methods were used to confirm the important role of primary Car oxocomplexes in different redox processes. It appeared that the yield of radiation-chemical bleaching of Fx, G-Fx, is 0.02-0.05 molecule/100 eV in the presence of oxygen, which in hundred times less the yield achieved in anaerobic conditions. The obtained results provide the evidence of Fx high level of stability under radiation, and demonstrate the supreme importance of reversible oxocomplex (Fx+delta...O2-delta) in stabilizing carotenoids in aerobic medium. The pulse radiolysis method with spectrophotometric registration of transients was used for generation and studying of mechanism O2.- interaction with different carotenoids. Introduction of any carotenoids containing oxygen (10(-5) M) in phosphate buffer solutions (pH 7.5) caused a red-shift of absorption maximum (from 5 to 15 nm) and difference in kinetics of O2.- decay. These results prove that radiation generated esolv- are directly accepted by (Car...O2) with consequent formation of superoxocomplexes (Car...O2.-) instead of O2.-. On the base of detecting the following transformation of superoxocomplexes the peroxocomplex (Car+...O2(2-)) was identified. In case of Fx a peroxocomplex (Fx+...O2(2-)) had absorption band with lambda max at approximately 360 nm. It is very important to mention that beta-carotene does not cause the similar effect and gets easily oxydized when exposed to the air.     

The effect of melaxen and valdoxan on the activity of the glutathione antioxidant system in rats with experimental hyperthyroidism

The activity of the glutathione system and conjugated diene content (CD) have been investigated in the liver and blood serum of rats with experimental hyperthyroidism treated with melaxen and valdoxan. The study of glutathione reductase (GR), glutathione peroxidase (GP) and glutathione transferase (GST) activities increased under this pathology has shown that administration of these compounds decreased these activities towards control levels. Melaxen and valdoxan administration increased reduced glutathione (GSH) content as compared with untreated hyperthyroid rats. This increase may be associated with its decreased utilization for detoxification of toxic products of free radical oxidation (FRO). Administration of the melatonin correcting drugs also tended to normalize the CD level increased in the liver and blood serum of hyperthyroid rats. Results of this study indicate that melaxen and valdoxan exhibit positive effect on free radical homeostasis. This appears to be accompanied by a decrease in the load of the glutathione antioxidant system in comparison with the examined pathology.     

Carotenoids, sexual signals and immune function in barn swallows from Chernobyl.

Carotenoids have been hypothesized to facilitate immune function and act as free-radical scavengers, thereby minimizing the frequency of mutations. Populations of animals exposed to higher levels of free radicals are thus expected to demonstrate reduced sexual coloration if use of carotenoids for free-radical scavenging is traded against use for sexual signals. The intensity of carotenoid-based sexual coloration was compared among three populations of barn swallows Hirundo rustica differing in exposure to radioactive contamination. Lymphocyte and immunoglobulin concentrations were depressed, whereas the heterophil:lymphocyte ratio, an index of stress, was enhanced in Chernobyl swallows compared to controls. Spleen size was reduced in Chernobyl compared to that of two control populations. Sexual coloration varied significantly among populations, with the size of a secondary sexual character (the length of the outermost tail feathers) being positively related to coloration in the two control populations, but not in the Chernobyl population. Thus the positive covariation between coloration and sexual signalling disappeared in the population subject to intense radioactive contamination. These findings suggest that the reliable signalling function of secondary sexual characters breaks down under extreme environmental conditions, no longer providing reliable information about the health status of males.     

The effect of high-molecular weight chitosans on the antioxidant and immune systems of the honeybee

High-molecular weight chitosan (200 kDa, 75% deacetylated) and N-succinoyl chitosan (300 kDa, 75% deacetylated) were shown to have a preadaptive effect and increase the lifespan of honeybees due to the induction of protective antioxidant and immune mechanisms. Chitosan with a molecular weight of 200 kDa had a fungistatic effect on a pathogenic fungus that causes ascospherosis, a disease of bee larvae and pupae.     

An experimental study on the self-reference effect

Self-reference at encoding increases the probability of recollective experience in recognition memory. Self-reference effect (SRE) in memory is observed when the degree of self-reference of to-be-remembered materials is varied. Usually items encoded in terms of self-reference are associated with significantly higher recall performance relative to items encoded in other ways, including semantic encoding. In our three experiments, four orientating tasks formed four levels in a between-subjects design. The conditions were rating personality traits with reference to self, mother, Lu Xun (a famous Chinese writer) or rating the traits on a negative-positive dimension. In a recognition test, subjects first identified old items and then indicated which of these were accompanied by recollective experience ('remember' responses) and which were recognized on some other basis ('know' responses). Our results showed that both the self-reference condition and mother condition were associated with the same highest propo     

An experimental study on the self-reference effect

Self-reference at encoding increases the probability of recollective experience in recognition memory. Self-reference effect (SRE) in memory is observed when the degree of self-reference of to-be-remembered materials is varied. Usually items encoded in terms of self-reference are associated with significantly higher recall performance relative to items encoded in other ways, including semantic encoding. In our three experiments, four orientating tasks formed four levels in a between-subjects design. The conditions were rating personality traits with reference to self, mother, Lu Xun (a famous Chinese writer) or rating the traits on a negative-positive dimension. In a recognition test, subjects first identified old items and then indicated which of these were accompanied by recollective experience (‘remember’ responses) and which were recognized on some other basis (‘know’ responses). Our results showed that both the self-reference condition and mother condition were associated with the same highest proportion of correct remember responses and the same lowest proportion of correct know responses. In contrast, for Western subjects, the self-reference condition, relative to the mother condition, was associated with a higher proportion of correct remember responses and a lower proportion of correct know responses. We discussed the results with reference to the HERA model (hemispheric encoding/retrieval asymmetry).     

The effect of 3,5-dicarbomethoxyphenylbiguanide on the activity of antioxidant enzymes

The effect of 3,5-dicarbomethoxyphenylbiguanide, which was selected with the Prediction of Activity Spectra of Substances (PASS) computer program, on the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione transferase in the heart and the blood serum of rats with experimental rheumatoid arthritis was investigated. The studied parameters changed towards control values when the tested compound was injected in animals with the pathology. These results can be explained by the cardioprotective and antioxidant activity of the compound. The data obtained during the study may be used for the development of new preventive and therapeutic agents for the treatment of the rheumatoid arthritis.     

Hepatoprotective and antioxidant activity of N-Trisaccharide in different experimental rats

ObjectivesTo investigate the hepatoprotective, antioxidant and antihyperlipidemic effect of N-Trisaccharide isolated from Cucumis prophetarum (L.) on different experimental rats.MethodsN-Trisaccharide (25 and 50 mg/kg.b.w), silymarin (25 mg/kg) and glibenclamide (25 mg/kg) was orally administered once daily for 28 days and toxicity evaluation studies were carried out. Liver damage was assessed by determining DNA damage, serum enzyme activities and hepatic histopathology of carbon tetrachloride (CCl₄) induced hepatic injury in rats. Enzymatic and non enzymatic antioxidant levels in liver and kidney were determined and biochemical parameters such as, serum lipid profile, renal function markers were estimated in type 2 diabetic rats.ResultsDNA fragmentation analysis revealed the protective effect of N-Trisaccharide on liver DNA damage. Histopathological studies indicated that CCl₄-induced liver injury was less severe in N-Trisaccharide (25 and 50 mg/kg) treated group. Given at the above doses conferred significant protection against the hepatotoxic actions of CCl₄ in rats, reducing serum markers like SGOT, SGPT, ALP, creatinine and urea levels back to near normal (p < 0.05) compared to untreated rats. In diabetic rats, N-Trisaccharide treatment significantly reversed abnormal status of enzymatic and non-enzymatic antioxidants levels to near normal. Also, serum lipids such as TG, TC, LDL-C and VLDL-C levels were significantly (p < 0.05) reduced compared to diabetic untreated rats.ConclusionPresent study results confirm that N-Trisaccharide possesses significant antihyperlipidemic, antioxidant and hepatoprotective properties.