Natural Variants of the Cellular Slime Mold Acrasis rosea

SYNOPSIS. Twenty different isolates of the cellular slime mold Acrasis rosea, obtained from diverse sources and geographic regions, were studied to determine similarities and differences in their development and structure in culture and their sensitivity or resistance to selected chemicals incorporated into the culture media. Six different classes of fruiting were defined based on the size, distribution, and type of sorocarps formed on the yeast, Rhodotorula, streaked on agar. In the course of these studies a significant mutant, NC-18V (variant), developed spontaneously from the wild type, normal parent strain NC-18N. The mutant differed considerably from all other Acrasis isolates, appeared several times in purified parental cultures, and represents the first laboratory derived variant of A. rosea to be described. Purified strains of the variant (V) and normal (N) cultures were obtained by single-spore isolation. Normal and variant amebae were mixed in ratios of 10:1 and 100:1 (N:V) and spore and stalk cells were selected from different sorocarps in various regions of the culture plate for analysis. The results of these selection experiments clearly indicate that the individual variant amebae have increased migratory ability and that they develop smaller, morphologically different, and more numerous sorocarps that form at distances further from the food source than NC-18N. Some isolates of Acrasis no longer were able to fruit and were classified as “non-fruiters” and a few other isolates formed only a few, small sorocarps on rare occasions. These isolates were mixed together in various combinations of 2 and 3 to screen for cell interaction, but no synergism contributing to fruiting was found. Although fruiting of many A. rosea isolates was inhibited by exposure to continuous light or constant darkness, some “escape”fruiting was noted in certain isolates even when small inocula were used. Single spore isolates of these escape fruiters still fruited in continuous light or dark, but fruiting was always greatly enhanced by a routine 12 hr light : 12 hr dark incubation cycle. It was shown by biochemical studies that actidione, crystal violet, malachite green, ethyl violet, and 5-fluorodeoxyuridine selectively killed some isolates and permitted a classification of isolates as either sensitive or resistant. In a further study of cell interaction between 2 different sets of Acrasis isolates with contrasting biochemical and morphologic markers the formation of neotypes or recombinants could not be demonstrated. The results of this study clearly indicate the existence of significant variation in A. rosea and the potential for application of these differences to developmental studies.     

Distribution of a centrosomal antigen during morphogenesis in the ciliated protozoan Euplotes

Ciliates assemble basal bodies in great number at many stages of the life-cycle. In order to understand their assembly mechanisms, we screened a library of monoclonal antibodies directed against pericentriolar material. One of these antibodies, CTR210, was used previously to follow steps of this assembly process: in Paraurostyla, new basal bodies appear along a scaffold of linear structures recognized by this antibody. The very unusual behavior of this antigen deserved confirmation in other species. In the present study, we show by immunofluorescence that, in another phylogenetically very distant species, Euplotes, basal bodies are assembled in the same pathway during division. In addition, this antibody recognizes a filamentous ring located at the division furrow and linking many basal body assemblages. By cell fractionation and cytoskeletal extraction, we obtained fractions enriched in basal bodies and associated material. Such fractions still display a high complexity in protein composition. These fractions were used to characterize the main target of the antibody as a doublet of 45 kDa. These results confirm previous results in terms of functionality of the protein recognized by the antibody, but raise new questions in terms of the assignment of the recognized protein to the HSP70 family as hypothesized previously.     

Evaluating long-term cellular effects of the arsenic species thio-DMAV: qPCR-based gene expression as screening tool

Thio-dimethylarsinic acid (thio-DMA^V) is a human urinary metabolite of the class 1 human carcinogen inorganic arsenic as well as of arsenosugars. Thio-DMA^V exerts strong cellular toxicity, whereas its toxic modes of action are not fully understood. For the first time, this study characterises the impact of a long-term (21 days) in vitro incubation of thio-DMA^V on the expression of selected genes related to cell death, stress response, epigenetics and DNA repair. The observed upregulation of DNMT1 might be a cellular compensation to counterregulate the in a very recent study observed massive global DNA hypomethylation after chronic thio-DMA^V incubation. Moreover, our data suggest that chronic exposure towards subcytotoxic, pico- to nanomolar concentrations of thio-DMA^V causes a stress response in human urothelial cells. The upregulation of genes encoding for proteins of DNA repair (Apex1, Lig1, XRCC1, DDB2, XPG, ATR) as well as damage response (GADD45A, GADD45G, Trp53) indicate a potential genotoxic risk emanating from thio-DMA^V after long-term incubation.     

Quercetin supplementation does not alter antioxidant status in humans

Abstract

This study measured the influence of ingesting quercetin on plasma measures for oxidative stress and antioxidant capacity. Male and female subjects (n = 1002) varying in age (18–85 years) and body mass index (BMI) (16.7–52.7 kg/m²) were studied. Subjects were randomized to one of three groups using double-blinded methods: placebo, 500 mg or 1000 mg quercetin/day with 125 mg or 250 mg vitamin C/day, respectively. Pre- and post-study fasting blood samples show that plasma quercetin increased in a dose-responsive manner. The pattern of change in plasma F₂-isoprostanes, oxidized low density lipoprotein, reduced glutathione, ferric reducing ability of plasma (FRAP) and oxygen radical absorbance capacity (ORAC) did not differ between supplementation groups or after adjustment for gender, age, BMI and disease status. In summary, quercetin supplementation over 12 weeks in doses of 500 mg or 1000 mg/day significantly increased plasma quercetin levels, but had no influence on several measures of oxidative stress and antioxidant capacity.     

Normal Superoxide Dismutase (SOD) Gene in Pregnancy-Induced Hypertension: Is the Decreased Sod Activity a Secondary Phenomenon?

Reactive oxygen species (ROS) have been implicated in the pathogenesis of pregnancy-induced hypertension (PIH). A genetic factor is also thought to be associated with the disease. The aim of the present study was to investigate whether decreased superoxide dismutase (SOD) activity in PIH resulted from gene abnormalities. Fourteen patients with PIH were enrolled in the study. Normal pregnant women and normal nonpregnant women served as controls. Genomic DNA and mRNA were isolated from white cells and subjected to Southern and Northern blot analysis with a 600 bp CuZn-SOD probe. SOD activity was also determined in the white blood cells and red blood cells. The results showed that SOD activity was significantly reduced in patients with PIH compared to both control groups. There were no significant differences in the size of the CuZn-SOD gene and its expression between the patients with PIH and the controls. This study confirmed that there was a decreased SOD activity in PIH but revealed neither major structural changes in the genomic DNA nor mRNA size of CuZn-SOD. Our results suggest that the decreased SOD levels in PIH are not due to abnormalities in the CuZn-SOD gene and are an acquired phenomenon which occurs during the development of the disease.     

Human urine: Epicatechin metabolites and antioxidant activity after cocoa beverage intake

Associations between cocoa consumption in humans, excreted metabolites and total antioxidant capacity (TAC) have been scarcely investigated. The aims of the study were to investigate the epicatechin (( ? )-Ec) metabolites excreted in urine samples after an intake of 40 g of cocoa powder along with the TAC of these urine samples and the relation between both the analyses. Each of the 21 volunteers received two interventions, one with a polyphenol-rich food (PRF) and one with a polyphenol-free food (PFF) in a randomized cross-over study. Urine samples were taken before and during 24 h at 0–6, 6–12 and 12–24 h periods after test intake. The excreted ( ? )-Ec metabolites and the TAC were determined in urine samples by LC-MS/MS and TEAC assay, respectively. The maximum excretion of ( ? )-Ec metabolites and the maximum TAC value were observed in urine samples excreted between 6 and 12 h after PRF consumption. Significance of TAC increase was found in urine samples excreted during 0–6 and 6–12 h (66.6 and 72.67%, respectively, with respect to the 0 h).     

Lipoic acid lessens Th1-mediated inflammation in lipopolysaccharide-induced uveitis reducing selectively Th1 lymphocytes-related cytokines release

Abstract

Inflammation results in the production of free radicals. We evaluated the anti-inflammatory and antioxidant capacity of lipoic acid in an experimental uveitis model upon a subcutaneous injection of endotoxin into Lewis rats. The role of oxidative stress in the endotoxin-induced uveitis model is well-known. Besides, the Th1 response classically performs a central part in the immunopathological process of experimental autoimmune uveitis. Exogenous sources of lipoic acid have been shown to exhibit antioxidant and anti-inflammatory properties. Our results show that lipoic acid treatment plays a preventive role in endotoxin-induced oxidative stress at 24 h post-administration and reduced Th1 lymphocytes-related cytokines by approximately 50–60%. Simultaneously, lipoic acid treatment caused a significant reduction in uveal histopathological grading and in the protein concentration in aqueous humors, but not in cellular infiltration.     

Thiol redox state and related enzymes in sclerotium-forming filamentous phytopathogenic fungi

Thiol redox state (TRS) reduced and oxidized components form profiles characteristic of each of the four main types of differentiation in the sclerotiogenic phytopathogenic fungi: loose, terminal, lateral-chained, and lateral-simple, represented by Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Sclerotinia minor, respectively. A common feature of these fungi is that as their undifferentiated mycelium enters the differentiated state, it is accompanied by a decrease in the low oxidative stress-associated total reduced thiols and/or by an increase of the high oxidative stress-associated total oxidized thiols either in the sclerotial mycelial substrate or in its corresponding sclerotium, indicating a relationship between TRS-related oxidative stress and sclerotial differentiation. Moreover, the four studied sclerotium types exhibit high activities of TRS-related antioxidant enzymes, indicating the existence of antioxidant protection of the hyphae of the sclerotium medulla until conditions become appropriate for sclerotium germination.     

Enzymatic browning reaction of apple juices prepared using a blender and a low-speed masticating household juicer

ABSTRACT

The aim of this study was to investigate the effect of juicer type (blender or LSM household juicer) on the browning reaction of apple juice and evaluate the remaining antioxidant activity in the juice. The blender apple juice showed a darker brown color and 4.5 times higher PPO activity than LSM apple juice. This result suggested that the blender caused severer damage to plastids in cells leading to leakage of PPO into the juice than the LSM juicer. The total polyphenol and flavonoid content of LSM apple juice was approximately 2 times higher than that of blender apple juice because polyphenols and flavonoids can be used as substrates by PPO. The antioxidant activity of LSM juice was higher than that of blender juice. Together, these results suggested that the LSM juicer is superior to the blender for preparation of fresh apple juices due to the minimization of enzymatic oxidation reactions.

Abbreviations: LSM: low-speed masticating; PPO: polyphenol oxidase; ABTS: 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); DPPH: 2,2-diphenyl-1-picrylhydrazyl