Effect of photon flux density and temperature on the production of halogenated monoterpenes by Plocamium cartilagineum (Plocamiaceae, Rhodophyta)

The effect of different photon flux densities (PFD) and temperatures on the relative growth rate (RGR) and the concentration of three halogenated monoterpenes in samples of Plocamium cartilagineum L.( Dixon), a marine alga (Rhodophyceae), were studied. The highest RGR (22.8 +/- 0.04 d(-1)) was obtained at 15 degreebC and 41 ,mol m(-2) s)(-1) of PFD and the lowest (18.0 +/- 0.12 d(-1)) was obtained at 18 degrees C and 120 micromol m(-2) s(-1). The different temperatures and light used in assays did not affect significantly the production of organic compounds. The production of mertensene and violacene was not affected significantly. However, compound 1 reached the highest concentration at 15 degrees C and 65 micromol m(-2) s(-1)). The relationship between growth and production of monoterpenes of P. cartilagineum and the effect of temperature and the PFD were analyzed.     

Purification and properties of a coagulant thrombin-like enzyme from the venom of Bothrops leucurus

A thrombin-like enzyme from Bothrops leucurus venom, named leucurobin (leuc), was purified by gel filtration, affinity and ion exchange chromatographies. Physicochemical studies indicated that the purified enzyme is a 35 kDa monomeric glycoprotein on SDS-PAGE under reducing conditions, which decreased to 29 kDa after deglycosylation with N-glycosidase F (PNGase F). The amino acid sequence of leuc was determined by automated sequencing of the intact native protein and peptides produced by digestion of the S-pyridyl-ethylated protein with trypsin. The protein sequence exhibits significant similarities with other serine proteases reported from snake venoms, and contains two potential sites of N-linked glycosylation. The proteinase split off fibrinopeptide A (FPA) rapidly from human fibrinogen; however, only negligible traces of fibrinopeptide B (FPB) were observed. In addition, the enzyme released the N-terminal peptide (Mr = 4572) containing the first 42 residues from the Bβ-chain. Leuc could neither activate factor XIII nor release kinins from heat-treated bovine plasma. Its specific clotting activity was equivalent to 198 NIH thrombin U/mg on human fibrinogen. Kinetic properties of leuc were determined using representative chromogenic substrates. The enzyme evoked the gyroxin syndrome when injected into the tail veins of mice at levels of 0.143 μg/g mouse. The inhibitory effects of PMSF and benzamidine on the amidolytic activity suggest that leuc is a serine proteinase, and inhibition by β-mercaptoethanol revealed the important role of the disulfide bonds in the stabilization of the native structure. Antibothropic serum, SBTI and EDTA had little or no effect on its amidolytic activity. However, the clotting effect of the enzyme was strongly inhibited by antibothropic serum. A Dixon plot showed that the hydrolysis of Bz-l-Arg-pNA by leuc was competitively inhibited by benzamidine (K_i = 1.61 ± 0.25 mM).     

High-Resolution Mapping of a Genetic Locus Regulating Preferential Carbohydrate Intake,Total Kilocalories,and Food Volume on Mouse Chromosome 17

The specific genes regulating the quantitative variation in macronutrient preference and food intake are virtually unknown. We fine mapped a previously identified mouse chromosome 17 region harboring quantitative trait loci (QTL) with large effects on preferential macronutrient intake-carbohydrate (Mnic1), total kilcalories (Kcal2), and total food volume (Tfv1) using interval-specific strains. These loci were isolated in the [C57BL/6J.CAST/EiJ-17.1-(D17Mit19-D17Mit50); B6.CAST-17.1] strain, possessing a ∼40.1 Mb region of CAST DNA on the B6 genome. In a macronutrient selection paradigm, the B6.CAST-17.1 subcongenic mice eat 30% more calories from the carbohydrate-rich diet, ∼10% more total calories, and ∼9% more total food volume per body weight. In the current study, a cross between carbohydrate-preferring B6.CAST-17.1 and fat-preferring, inbred B6 mice was used to generate a subcongenic-derived F₂ mapping population; genotypes were determined using a high-density, custom SNP panel. Genetic linkage analysis substantially reduced the 95% confidence interval for Mnic1 (encompassing Kcal2 and Tfv1) from 40.1 to 29.5 Mb and more precisely established its boundaries. Notably, no genetic linkage for self-selected fat intake was detected, underscoring the carbohydrate-specific effect of this locus. A second key finding was the separation of two energy balance QTLs: Mnic1/Kcal2/Tfv1 for food intake and a newly discovered locus regulating short term body weight gain. The Mnic1/Kcal2/Tfv1 QTL was further de-limited to 19.0 Mb, based on the absence of nutrient intake phenotypes in subcongenic HQ17IIa mice. Analyses of available sequence data and gene ontologies, along with comprehensive expression profiling in the hypothalamus of non-recombinant, cast/cast and b6/b6 F₂ controls, focused our attention on candidates within the QTL interval. Zfp811, Zfp870, and Btnl6 showed differential expression and also contain stop codons, but have no known biology related to food intake regulation. The genes Decr2, Ppard and Agapt1 are more appealing candidates because of their involvement in lipid metabolism and down-regulation in carbohydrate-preferring animals.     

Immunohistochemical evidence for the expression and induction of paraoxonase in rat liver, kidney, lung and brain tissue. Implications for its physiological role

Studies on the localization of paraoxonases (PON's) are of interest because of its involvement in both the detoxication of activated organophosphorus pesticides and in the prevention of peroxidative damage to phospholipids and cholesteryl-esters in LDL and HDL particles and cell membranes during the atherogenic process. In the present study, we have investigated the cellular localization of PON1 by immunohistochemistry in different rat tissues. The protein was mainly detected in the endothelial lining of every tissue studied (liver, kidney, lung and brain). Besides, it was found in hepatocytes from the centrolobular region of the liver, in the glomeruli and basal pole of the proximal convoluted tubule of the kidney, in cells from bronchiolar epithelium and type I pneumocytes of the lung, and in leptomeningeal cells, ependymal cells and ventricular side of choroid plexus cells of the brain. However, neurons and glia lacked immunostaining. After 3-methylcholanthrene induction an increase in the intensity of immunostaining was observed in the same areas, as well as an additional staining in midzonal hepatocytes. On the basis of the tissue distribution observed for PON1, it is proposed that this enzyme might have a function related to the inactivation of oxidative stress by-products (either at a cellular level or blood-vessel wall) and other environmental chemicals. At present it has not yet been established whether the paraoxonase detected in the various tissues is truly a product of the PON1 gene or could represent products of the PON2 or PON3 genes.     

Seasonal suitability of three rubber tree clones to Calacarus heveae (Acari, Eriophyidae)

The suitability of rubber tree clones to Calacarus heveae was inferred from the life cycle, reproduction and survivorship of this mite. The assays were performed under controlled conditions with leaflets detached from 6-year-old plants. The development of 20 C. heveae individuals on each of the clones GT 1, PB 235 and RRIM 600 was analysed. This experiment was performed four times during periods when C. heveae was abundant in the field: (P1) November–December 2005, (P2) January–February, (P3) March–April and (P4) May–June 2006. Accordingly, the leaflets used in each assay represented the physiological condition of the host plant during each period. This approach allowed us to evaluate the seasonal suitability of rubber tree clones to C. heveae. We observed seasonal differences in the suitability of rubber tree clones to mite attack. The mites reared on the PB235 had a shorter development period, the highest egg production and highest survivorship. This evidence showed that the PB 235 was the most suitable of those tested. We also observed that the leaflets used in the assays during periods P2 and P3 were the most favourable for the development of C. heveae. This finding emphasises the seasonal suitability of rubber tree leaflets. On the other hand, GT 1 showed higher resistance against C. heveae than did RRIM 600 and PB 235, primarily during the period from November to February. This result indicated that use of the GT 1 clone to control the mite might represent an alternative for growers.     

DNA damage induced by endogenous aldehydes: current state of knowledge

DNA damage plays a major role in various pathophysiological conditions including carcinogenesis, aging, inflammation, diabetes and neurodegenerative diseases. Oxidative stress and cell processes such as lipid peroxidation and glycation induce the formation of highly reactive endogenous aldehydes that react directly with DNA, form aldehyde-derived DNA adducts and lead to DNA damage. In occasion of persistent conditions that influence the formation and accumulation of aldehyde-derived DNA adducts the resulting unrepaired DNA damage causes deregulation of cell homeostasis and thus significantly contributes to disease phenotype. Some of the most highly reactive aldehydes produced endogenously are 4-hydroxy-2-nonenal, malondialdehyde, acrolein, crotonaldehyde and methylglyoxal. The mutagenic and carcinogenic effects associated with the elevated levels of these reactive aldehydes, especially, under conditions of stress, are attributed to their capability of causing directly modification of DNA bases or yielding promutagenic exocyclic adducts. In this review, we discuss the current knowledge on DNA damage induced by endogenously produced reactive aldehydes in relation to the pathophysiology of human diseases.