Effect of subchronic exposure to malathion on metabolic parameters in the rat

This study investigates the effects of subchronic exposure to organophosphate insecticide Malathion (Fyfanon 50 EC 500 g/l) of commercial grade. It was administered intragastrically by stomach tube in the amount of 1 ml of corn oil containing 100 mg/kg body weight (BW) daily for 32 days. At the end of the experiment, acetylcholinesterase activity (AChE), haematocrit value, haemoglobin content, and blood glucose concentration were estimated. The liver and the skeletal muscle were removed to determine hepatic and muscular glycogen, hepatic proteins and lipids contents. No sign of toxicity was observed until the end of experiment. No significant change in the haematocrit value was observed, in spite of the significant increase in haemoglobin content, which can be considered as an adaptive situation in order to guarantee a good oxygenation in response to pulmonary damage induced following subchronic exposure to organophosphorus compound. Malathion intoxication decreased significantly hepatic proteins and lipid contents that could be associated to liver gluconeogenesis. This result was coupled with a significant decrease in muscular glycogen rate, which indicates a stimulated glycogenolysis in favour of glucose release into the blood until reaching hyperglycaemia. Several studies indicate that hyperglycaemia is temporary, which is probably due to a stimulated glycogenesis that increases hepatic glycogen deposition and return of glucose to control levels, as demonstrated in our study. One possible explanation for these results could be the turnover of glucose by a succession between its release via glycogenolysis and gluconeogenesis, which involves abnormal hyperglycaemia, and its storage via glycogenesis in subchronic exposure to malation.     

Induction of Epstein-Barr virus (EBV) lytic cycle in vitro causes oxidative stress in lymphoblastoid B cell lines

Here, we investigated the effect of induction of the Epstein-Barr virus (EBV) viral lytic cycle on the oxidant/antioxidant balance in three lymphoblastoid cell lines: B95-8, Raji, and LCL C1. The induction of the EBV lytic cycle was done by a non-stressing dose of 12-0-tetradecanoylphorbol-13-acetate (8 nM). Oxidative stress was assessed by measuring malondialdehyde as a parameter of lipid peroxidation, the levels of glutathione, and the activities of three antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase). After 48 h (peak of lytic cycle), a significant decrease in superoxide dismutase activity was observed in B95-8, Raji, and LCL C1 cells (P < 0.05). In addition, in B95-8 cells also a significant decrease of catalase activity was detected (P < 0.05). The glutathione peroxidase activity and the glutathione level were not significantly modified by the induction in any of the cell lines. We found a significant rise in malondialdehyde levels in B95-8, Raji, and LCL C1 cells after the induction of the lytic cycle compared to controls (P < 0.05). In conclusion, induction of EBV lytic cycle in lymphoblastoid cells causes increased oxidative stress in the host cells within 48 h, a process that could be involved in malignant transformations.     

A new Lactobacillus plantarum strain, TN8, from the gastro intestinal tract of poultry induces high cytokine production

This study aimed to determine the probiotic potential of 100 strains of Lactic Acid Bacteria (LAB) isolated from different intestinal segments of indigenous poultry in Tunisia. The strains were submitted to a battery of standard tests and criteria commonly used for determining their probiotic properties and attributes. The findings revealed that 19 of the isolates exhibited antimicrobial activity against 4 pathogenic bacteria, and that 4 (TN1, TN8, TN7, and TN13) showed good resistance to pH 3 and 5% bovine bile. Three isolates, namely TN1, TN8, and TN13, showed sensitivity to several antibiotics and were, therefore, selected for further enzymatic activity assays. Two isolates, namely TN1 and TN8, showed high efficacy of adhesion to chicken enterocytes. The cytokines released after stimulation by the two isolates showed high anti-inflammatory profiles, with an increased rate of Interleukin-10 (IL-10) production for the TN8 strain. Showing the highest performance, TN8 was submitted to 16S rRNA gene sequencing, which revealed that the strain was of the species Lactobacillus plantarum. Overall, the findings indicate that the Lactobacilli from poultry intestine has a number of promising properties that make it candidate for application as a probiotic additive in poultry industry.     

Effect of dehydration on nitric oxide, corticotropic and vasopressinergic axis in rat

Effect of dehydration on nitric oxide, corticotropic and vasopressinergic axis in rat. The purpose of our work is to study, in the male 'Wistar' rat, the effects of a chronic dehydration, by deprivation of water for three days out of four, during four repeated cycles, on the evolution of certain blood variables, on the activities of both corticotropic and vasopressinergic axis and on the synthesis of nitric oxide. The chronic dehydration causes a considerable reduction of the body weight, an activation of the vasopressinergic axis and an increase in the circulating rates of the nitrates/nitrites, which represent the final metabolites of the reaction of oxidation of nitric oxide. The pituitary-adrenal axis is not statistically affected by the chronic dehydration. This seems to be in favour of a possible adaptation of corticotropic axis to chronic water deprivation. The activation of synthesis of nitric oxide shows its implication in the regulation of the water balance and its buffer effect on vasoconstriction and hypertension induced by water stress.     

Ocean warming and acidification alter the behavioral response to flow of the sea urchin Paracentrotus lividus

Ocean warming (OW) and acidification (OA) are intensively investigated as they pose major threats to marine organism. However, little effort is dedicated to another collateral climate change stressor, the increased frequency, and intensity of storm events, here referred to as intensified hydrodynamics. A 2‐month experiment was performed to identify how OW and OA (temperature: 21°C; pH_T: 7.7, 7.4; control: 17°C‐pH_T7.9) affect the resistance to hydrodynamics in the sea urchin Paracentrotus lividus using an integrative approach that includes physiology, biomechanics, and behavior. Biomechanics was studied under both no‐flow condition at the tube foot (TF) scale and flow condition at the individual scale. For the former, TF disk adhesive properties (attachment strength, tenacity) and TF stem mechanical properties (breaking force, extensibility, tensile strength, stiffness, toughness) were evaluated. For the latter, resistance to flow was addressed as the flow velocity at which individuals detached. Under near‐ and far‐future OW and OA, individuals fully balanced their acid‐base status, but skeletal growth was halved. TF adhesive properties were not affected by treatments. Compared to the control, mechanical properties were in general improved under pH_T7.7 while in the extreme treatment (21°C‐pH_T7.4) breaking force was diminished. Three behavioral strategies were implemented by sea urchins and acted together to cope with flow: improving TF attachment, streamlining, and escaping. Behavioral responses varied according to treatment and flow velocity. For instance, individuals at 21°C‐pH_T7.4 increased the density of attached TF at slow flows or controlled TF detachment at fast flows to compensate for weakened TF mechanical properties. They also showed an absence of streamlining favoring an escaping behavior as they ventured in a riskier faster movement at slow flows. At faster flows, the effects of OW and OA were detrimental causing earlier dislodgment. These plastic behaviors reflect a potential scope for acclimation in the field, where this species already experiences diel temperature and pH fluctuations.     

Hydroacoustic fish biomass assessment in man-made lakes in Tunisia: horizontal beaming importance and diel effect

We used a Simrad EK60 echosounder equipped with two split-beam transducers to develop a sampling strategy for assessing fish resources in Tunisian man-made lakes. Day and night surveys, using vertical and horizontal beaming, were carried out between December 2006 and February 2007, a period when fish catchability is high. Four reservoirs with differing surface areas and bathymetries were selected. Echogram analysis revealed that fish communities were mainly composed of individual targets. A few schools were detected near the surface during daylight, but these schools dispersed slightly at night. In these multispecies reservoirs, considerable day and night differences in density existed, but with no clear trend. Target strength (TS) distribution mode values detected at night were always lower or equal to daytime values. Biomass estimates were significantly higher during daytime in three reservoirs, corresponding with higher TS modal values. In the other reservoir, the biomass estimate was significantly higher during nighttime corresponding with higher mean density during this period. Using only a vertically aimed transducer in our study reservoirs would have led to an underestimate of density and biomass by 5–100% and 20–100%, respectively, depending on the man-made lake. We conclude that acoustic sampling in our reservoirs must be done during day and night and that both vertical and horizontal beaming must be used to obtain the best possible picture of the fish stocks.     

Relationships between proteasomes and RNA

The 20S proteasome (prosome) is a highly organized multi-protein complex with approximate molecular weight of about 700 kDa. Whilst the role of the proteasome in the processing and turnover of cellular proteins is becoming clearer, its relationship with RNA remains obscure. Over the last decade the possibility of association of proteasomes with specific RNAs or mRNPs have been particularly controversial. Proteasomes were reported to inhibit translation of viral mRNAs and to be tightly associated with RNase activity. It is possible that proteasomes are also involved in cellular RNA breakdown and RNA processing like prokaryotic RNase E.