No abstract

Background: Insects provide tractable models for enhancing our understanding of the physiological and cellular processes that enable survival at extreme low temperatures. They possess three main strategies to survive the cold: freeze tolerance, freeze avoidance or cryoprotective dehydration, of which the latter method is exploited by our model species, the Arctic springtail Megaphorura arctica, formerly Onychiurus arcticus (Tullberg 1876). The physiological mechanisms underlying cryoprotective dehydration have been well characterised in M. arctica and to date this process has been described in only a few other species: the Antarctic nematode Panagrolaimus davidi, an enchytraied worm, the larvae of the Antarctic midge Belgica antarctica and the cocoons of the earthworm Dendrobaena octaedra. There are no in-depth molecular studies on the underlying cold survival mechanisms in any species.

Diabetic pregnancy is often complicated by a number of pathological conditions among which is increased oxidative stress. This study was conducted to investigate the parameters of oxidative stress in 90 patients divided into the three groups: pregnant women with Type 1 diabetes mellitus, healthy pregnant women and non-pregnant women. In pregnancy groups all parameters were followed in 1st, 2nd and 3rd trimester. Diabetic control was monitored by fasting blood glucose and glycosylated hemoglobin (HbA(1c)) and these values, as well as measured biochemical parameters (urea, creatinine, total cholesterol and uric acid), were appropriate throughout the study. The concentration of TBARS, as a measure of lipid peroxidation, and activity of antioxidant enzymes superoxide dismutase (Cu, Zn-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were investigated in hemolysate of erythrocytes. TBARS concentration increased significantly in pregnant women when compared with control group (non-pregnant women), as well as in pregnant diabetics compared with healthy pregnant women. The SOD activity was gradually increased in the group of normal pregnant women vs. non-pregnant group, but decreased significantly in the group of diabetic pregnant women. Catalase activity was significantly increased only in 3rd trimester diabetic pregnant women. Increased lipid peroxidation and reduced antioxidant status, despite good diabetic control, show that pregnant women are exposed to oxidative stress to a greater degree than controls.

Antioxidant enzymes, total glutathione (GSH), and ascorbic acid (ASA) were determined in whole body homogenates of nondiapausing larvae, diapausing larvae during the diapausing period (October, December, and February), and in pupae emerged from both diapausing and nondiapausing larvae of the European corn borer (Ostrinia nubilalis, Hubn., Lepidoptera: Pyralidae). The activities of catalase, selenium nondependent glutathione peroxidase (GPx), and glutathione-S-transferase (GST), as well as the content of GSH and ASA, were found to vary throughout the larval diapause. Compared to diapausing larvae, nondiapausing larvae were higher in levels of catalase, GPx, GST, and dehydroascorbate reductase (DHAR) activity. GSH content was also increased. However, nondiapausing larvae contained less ASA than diapausing ones. Pupae had higher GPx and GST activity and an increased ASA content compared to larvae. The pupae emerged from nondiapausing larvae had higher GST, glutathione reductase (GR), and DHAR activities, but lower GPx activity and ASA content than those emerged from diapausing larvae. Correlation analysis revealed differences in the way the antioxidant level is equilibrated for a particular stage and developmental pattern. The results suggest that cellular antioxidants are involved in both the protection of cells and the regulation of redox levels during the pre-adult stages of Ostrinia nubilalis. Arch. Insect Biochem. Physiol. 55:79-89, 2004.

No abstract

Background: Ice, snow and temperatures of -14°C are conditions which most animals would find difficult, if not impossible, to survive in. However this exactly describes the Arctic winter, and the Arctic springtail Onychiurus arcticus regularly survives these extreme conditions and re-emerges in the spring. It is able to do this by reducing the amount of water in its body to almost zero: a process that is called "protective dehydration". The aim of this project was to generate clones and sequence data in the form of ESTs to provide a platform for the future molecular characterisation of the processes involved in protective dehydration.

ABSTRACT:The effects of clinoptilolite in pig's diets were examined on sixty Landrace × Yorkshire crossbred pigs of both sexes divided into two groups: 1. control group, with basal diets; 2. treatment, with basal diets supplemented with 5 g clinoptilolite per 1 kg diet (Cp group). Feed and water were available ad libitum. Individual live weights were recorded on days 45, 90 and 135 of the experiment. Feed consumptions were recorded weekly. Blood was drawn from the anterior vena cava of each pig at day 135 for the determination of serum biochemical parameters. During the first 90 days of the experiment pigs from the Cp group had higher body weight gain (BWG) compared with the control group (+2.5% and +7.0%, respectively) but in the finishing phase of growing their growth parameters were significantly lower (-4.8%). Blood serum biochemical parameters from all experimental pigs were generally within the normal range. Higher triglyceride concentration, lower total cholesterol concentration and increased activity of AST were recorded in the serum of the Cp group.

Abstract. Many insects in temperate regions overwinter in diapause, during which they are cold hardy. In these insects, one of the metabolic adaptations to the unfavorable environmental conditions is the synthesis of cryoprotectants/anhydroprotectants. The aim of this study was to investigate the connection between the antioxidative system and synthesis of cryoprotectants (mainly glycerol) in diapausing larvae of the European corn borer, Ostrinia nubilalis (Lepidoptera: Pyralidae). At two periods during diapause (November and February), in three groups of insects (kept under field conditions; -12°C for two weeks; 8°C for two weeks), the activity of key enzymes of the antioxidative system and oxidative part of the hexose monophosphate shunt were measured: superoxide dismutase, catalase, non selenium glutathione peroxidase, glutathione S-transferase, glutathione reductase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, as well that of the antioxidative components: total glutathione and ascorbate, and dehydroascorbate reductase. There was a higher activity of antioxidative enzymes at the beginning of the diapause period (November) compared to late diapause (February), while glutathione and ascorbate were higher in February. Similarly, there was a lower activity of the hexose monophosphate shunt enzymes in February. Exposure of larvae to -12°C resulted in an elevation of hexose monophosphate shunt enzyme activity, especially in November. This was accompanied by a significant increase in glycerol content in February. Changes in ascorbate levels and dehydroascorbate reductase activity in both experimental groups (-12°C and 8°C) suggest a connection between the antioxidative system, metabolism during diapause and cold hardiness. Our results support the notion that antioxidative defense in larvae of Ostrinia nubilalis is closely connected with metabolic changes characteristic of diapause, mechanisms of cold hardiness involved in diapause and the maintenance of a stable redox state.