Antioxidant activity of brown alga Saccharina bongardiana from Kamchatka (Pacific coast of Russia). A methodological approach

The present study aims to investigate the levels of polyphenols and antioxidant activity in one of the most important commercial species of seaweeds in Kamchatka, an edible brown seaweed Saccharina bongardiana. Six extracts of S. bongardiana, acetone, methanol, ethanol, and the respective 70 % aqueous solutions, were assessed for total phenol content in order to determine the most efficient extracting solvent. The total phenol content was measured by the Folin–Ciocalteu method and expressed as phloroglucinol equivalents (PGE). The antioxidant tests used were 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, linoleic acid-β carotene oxidation inhibiting assay, and Fe²⁺ ion chelating method. Higher phenolic contents were obtained using aqueous organic solvents, as compared to the respective absolute solvents; 70 % acetone was found to be the most efficient solvent (1.039 mg PGE 100 mg^?1 dry algal powder). High significant correlations were noted between total phenol content and the tested antioxidant activities; so the aqueous organic extracts exhibited the highest antioxidant activities versus DPPH radicals (EC₅₀ values of 0.6–1.1 mg dry weight (DW) mL^?1), linoleic acid-β carotene oxidation (74–78 % at 0.8 mg DW mL^?1), as well as ferrous ions (EC₅₀ values of 5.0–7.9 mg DW mL^?1). Some methodological recommendations regarding the assays used and the expression of results are proposed.     

The role of angiotensin II,endothelin-1 and transforming growth factor-β as autocrine/paracrine mediators of stretch-induced cardiomyocyte hypertrophy

Cardiac hypertrophy is a compensatory response of myocardial tissue upon increased mechanical load. Of the mechanical factors, stretch is rapidly followed by hypertrophic responses. We tried to elucidate the role of angiotensin II (AII), endothelin-1 (ET-1) and transforming growth factor- (TGF-) as autocrine/paracrine mediators of stretch-induced cardiomyocyte hypertrophy. We collected conditioned medium (CM) from stretched cardiomyocytes and from other stretched cardiac cells, such as cardiac fibroblasts, endothelial cells and vascular smooth muscle cells (VSMCs). These CMs were administered to stationary cardiomyocytes with or without an AII type 1 (AT₁) receptor antagonist (losartan), an ET-1 type A (ET_A) receptor antagonist (BQ610), or anti-TGF- antibodies. By measuring the mRNA levels of the proto-oncogene c-fos and the hypertrophy marker gene atrial natriuretic peptide (ANP), the molecular phenotype of the CM-treated stationary cardiomyocytes was characterized.Our results showed that c-fos and ANP expression in stationary cardiomyocytes was increased by AII release from cardiomyocytes that had been stretched for 60 min. Stretched cardiomyocytes, cardiac fibroblasts and endothelial cells released ET-1 which led to increased c-fos and ANP expression in stationary cardiomyocytes. ET-1 released by stretched VSMCs, and TGF- released by stretched cardiac fibroblasts and endothelial cells, appeared to be paracrine mediators of ANP expression in stationary cardiomyocytes.These results indicate that AII, ET-1 and TGF- (released by cardiac and vascular cell types) act as autocrine/paracrine mediators of stretch-induced cardiomyocyte hypertrophy. Therefore, it is likely that in stretched myocardium the cardiomyocytes, cardiac fibroblasts, endothelial cells and VSMCs take part in intercellular interactions contributing to cardiomyocyte hypertrophy.     

Lethal and pre-lethal effects of a fungal biopesticide contribute to substantial and rapid control of malaria vectors

Rapidly emerging insecticide resistance is creating an urgent need for new active ingredients to control the adult mosquitoes that vector malaria. Biopesticides based on the spores of entomopathogenic fungi have shown considerable promise by causing very substantial mortality within 7-14 days of exposure. This mortality will generate excellent malaria control if there is a high likelihood that mosquitoes contact fungi early in their adult lives. However, where contact rates are lower, as might result from poor pesticide coverage, some mosquitoes will contact fungi one or more feeding cycles after they acquire malaria, and so risk transmitting malaria before the fungus kills them. Critics have argued that 'slow acting' fungal biopesticides are, therefore, incapable of delivering malaria control in real-world contexts. Here, utilizing standard WHO laboratory protocols, we demonstrate effective action of a biopesticide much faster than previously reported. Specifically, we show that transient exposure to clay tiles sprayed with a candidate biopesticide comprising spores of a natural isolate of Beauveria bassiana, could reduce malaria transmission potential to zero within a feeding cycle. The effect resulted from a combination of high mortality and rapid fungal-induced reduction in feeding and flight capacity. Additionally, multiple insecticide-resistant lines from three key African malaria vector species were completely susceptible to fungus. Thus, fungal biopesticides can block transmission on a par with chemical insecticides, and can achieve this where chemical insecticides have little impact. These results support broadening the current vector control paradigm beyond fast-acting chemical toxins.     

Vitamin D in a Northern Canadian First Nation Population: Dietary Intake,Serum Concentrations and Functional Gene Polymorphisms

The wide spectrum of vitamin D activity has focused attention on its potential role in the elevated burden of disease in a northern Canadian First Nations (Dené) cohort. Vitamin D insufficiency, and gene polymorphisms in the vitamin D receptor (VDR) and vitamin D binding protein (VDBP) have been implicated in susceptibility to infectious and chronic diseases. The objectives of this study were to determine the contribution of vitamin D from food, and measure the serum concentrations of 25-hydroxyvitamin D₃ (25-OHD₃) and VDBP in Dené participants. Single nucleotide polymorphisms (SNPs) associated with the dysregulation of the innate immune response were typed and counted. Potential correlations between the SNPs and serum concentrations of 25-OHD₃ and VDBP were evaluated. Venous blood was collected in summer and winter over a one-year period and analyzed for 25-OHD₃ and VDBP concentrations (N = 46). A questionnaire was administered to determine the amount of dietary vitamin D consumed. Sixty-one percent and 30% of the participants had 25-OHD₃ serum concentrations <75 nmol/L in the winter and summer respectively. Mean vitamin D binding protein concentrations were within the normal range in the winter but below normal in the summer. VDBP and VDR gene polymorphisms affect the bioavailability and regulation of 25-OHD₃. The Dené had a high frequency of the VDBP D432E-G allele (71%) and the Gc1 genotype (90%), associated with high concentrations of VDBP and a high binding affinity to 25-OHD₃. The Dené had a high frequency of VDR Fok1-f allele (82%), which has been associated with a down-regulated Th1 immune response. VDBP and VDR polymorphisms, and low winter 25-OHD₃ serum concentrations may be risk factors for infectious diseases and chronic conditions related to the dysregulation of the vitamin D pathway.     

Isolation and sequence analysis of P450 genes from a pyrethroid resistant colony of the major malaria vector Anopheles funestus.

Pyrethroid resistance has been demonstrated in populations of Anopheles funestus from South Africa and southern Mozambique. Resistance is associated with elevated P450 monooxygenase enzymes. In this study, degenerate primers based on conserved regions of Anopheles gambiae P450 CYP4, 6 and 9 families were used to amplify genomic and cDNA templates from A. funestus. A total of 12 CYP4, 12 CYP6 and 7 CYP9 partial genes have been isolated and sequenced. BLAST results revealed that A. funestus P450s generally have a high sequence identity to A. gambiae with above 75% identity at the amino acid level. The exception is CYP9J14. The A. gambiae P450 showing highest identity to CYP9J14 exhibits only 55% identity suggesting that CYP9J14 may have arisen from a recent duplication event. Molecular phylogenetic analysis based on amino acid sequences also supported this hypothesis. Intron positions, but not size, were highly conserved between the two species. The high level of orthology that exists in the P450 gene families of these two species may facilitate the prediction of individual P450 protein function.     

Effect of larval host food substrate on egg load dynamics, egg size and adult female size in four species of braconid fruit fly (Diptera: Tephritidae) parasitoids

Life history theory predicts that individuals will allocate resources to different traits so as to maximize overall fitness. Because conditions experienced during early development can have strong downstream effects on adult phenotype and fitness, we investigated how four species of synovigenic, larval-pupal parasitoids that vary sharply in their degree of specialization (niche breadth) and life history (Diachasmimorpha longicaudata, Doryctobracon crawfordi, Opius hirtus and Utetes anastrephae), allocate resources acquired during the larval stage towards adult reproduction. Parasitoid larvae developed in a single host species reared on four different substrates that differed in quality. We measured parasitoid egg load at the moment of emergence and at 24 h, egg numbers over time, egg size, and also adult size. We predicted that across species the most specialized would have a lower capacity to respond to changes in host substrate quality than wasps with a broad host range, and that within species, females that emerged from hosts that developed in better quality substrates would have the most resources to invest in reproduction. Consistent with our predictions, the more specialized parasitoids were less plastic in some responses to host diet than the more generalist. However, patterns of egg load and size were variable across species. In general, there was a remarkable degree of reproductive effort-allocation constancy within parasitoid species. This may reflect more “time-limited” rather than “egg-limited” foraging strategies where the most expensive component of reproductive success is to locate and handle patchily-distributed and fruit-sequestered hosts. If so, egg costs, independent of degree of specialization, are relatively trivial and sufficient resources are available in fly larvae stemming from all of the substrates tested.