Selection of lactic acid bacteria as candidate probiotics and in vivo test on Artemia nauplii

Lactic acid bacteria (LAB) were isolated from rotifer cultures in a marine hatchery to search for potential probiotics for marine animals. Fifteen strains were first selected among a total of 55, according to antibacterial activity against Vibrio sp. Among eight strains identified as Lactobacillus casei, four were highly adhesive, suggesting some ability for surface colonization. The other strains were identified as Lactobacillus plantarum, Lactobacillus dextrinicus, and Leuconostoc sp. To validate probiotic potential, Artemia were challenged against pathogenic Vibrio alginolyticus, with or without one of six selected LAB strains. The six strains protected Artemia against the pathogen, to some extent on condition that nutrient enrichment was provided. La. casei BR51 and X2 were preferred, as they were efficient even in the absence of nutrient supply. La. casei X2 was finally selected as candidate probiotic, due to the best growth performances of Artemia, with or without the pathogen.     

Application of for the identification and management of hybrid poplar accessions

Molecular markers are a powerful tool with many potential applications in agriculture and forestry. In particular, can provide information on the relatedness of various clones or varieties that are difficult to distinguish morphologically, thus helping in the management of plant accessions and in breeding programs. The goal of this study is to genotype 15 clones used in the Prairie Farm Rehabilitation Administration (PFRA) breeding programs. Simple Sequence Repeat (SSR, or microsatellite markers) were selected for genotyping using the polymerase chain reaction (PCR). This type of marker is considered the method of choice due to their abundance, polymorphism and reliability compared to other types of . Sixteen previously isolated and characterized in aspen (Populus tremuloides) and other poplar species (Populus spp.) were initially tested. Nine markers were selected based on the “informativeness” and the quality of the amplification products. The nine markers were combined in groups of three to improve the efficiency of the genotyping technique. Using the nine markers, the average number of alleles per locus was 5.1. The expected and observed heterozygosity ranges were 0.32 to 0.80 and 0.13 to 0.92 respectively. The results also show that it is possible to produce a unique “DNA fingerprint” specific to each of the 15 hybrid poplar clones with the nine . In this study it was possible to show that two clones, P. ‘Melville’ and P. x ‘Walker’ used in Saskatchewan have similar DNA profiles with nine markers and a combined probability of identity of 2.23×10⁻⁶ suggesting that these clones are identical. This observation will prevent unnecessary duplication of the two accessions in breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inhibitory activity on amyloid-beta aggregation and antioxidant properties of Crocus sativus stigmas extract and its crocin constituents

Crocus sativus stigmas are one of the widely known spices (saffron) and consist of unusually polar carotenoids. Alzheimer's disease is characterized pathologically by deposition of amyloid beta-peptide (Abeta) fibrils. Oxidation is thought to promote Abeta fibril formation and deposition. To identify agents inhibiting the pathogenesis of Alzheimer's disease, we examined in vitro the antioxidant properties of extract of C. sativus stigmas and its effect on Abeta(1-40) fibrillogenesis. The antioxidant properties were determined by measuring the ferric-reducing antioxidant power and Trolox-equivalent antioxidant capacity, while its effects on Abeta-aggregation and fibrillogenesis were studied by thioflavine T-based fluorescence assay and by DNA binding shift assay. The water:methanol (50:50, v/v) extract of C. sativus stigmas possesses good antioxidant properties, higher than those of tomatoes and carrots, and inhibited Abeta fibrillogenesis in a concentration and time-dependent manner. The main carotenoid constituent, trans-crocin-4, the digentibiosyl ester of crocetin, inhibited Abeta fibrillogenesis at lower concentrations than dimethylcrocetin, revealing that the action of the carotenoid is enhanced by the presence of the sugars. Our findings suggest the possible use of C. sativus stigma constituents for inhibition of aggregation and deposition of Abeta in the human brain.     

Fetal protection against bovine viral diarrhoea type 1 virus infection after one administration of a live-attenuated vaccine

A modified-live vaccine has been shown previously to prevent fetal infection with bovine viral diarrhoea virus (BVDV)-2 and, to some extent BVDV-1, when used in association with an inactivated vaccine in a two-step vaccination protocol. In this challenge study, the modified-live vaccine used alone was able to protect 13 heifers between 49 and 96 days of gestation at challenge from leucopenia and virus replication and, for a 4-month period, to prevent fetal infection. The efficacy of the BVDV-1f 22146/Han81 challenge was demonstrated by virus isolation from the fetuses of all nine non-vaccinated, control heifers. However, the small number of heifers tested meant that the vaccination failure rate could be as high as 10% in the field.     

Lutte contre les chenilles des noctuelles défoliatrices de la culture de la menthe verte (Mentha spicata L.) au Maroc

Defoliating caterpillars from the family Noctuidae are the most destructive insect pests on spearmint crop in Morocco. To control these pests, the growers apply several applications of non‐selective insecticides that are sometimes not registered for this use. This study investigates the efficacy of a set of selective chemical insecticides and other insecticides registered for organic farming against the defoliating caterpillars for better protection and in order to limit pesticide residues. Two insecticides authorized in organic farming and four other chemical insecticides were tested against the defoliating caterpillars under field conditions, following the randomized complete block experimental design with three replications. The comparative study of the efficacy of the different insecticides tested showed an average caterpillar reduction of 89.4, 82.5 and 68.1% with a defoliation reduction of 57.1, 53.8 and 43.9% for two of the tested synthetic insecticides, chlorantraniliprole (15cc/hl), emamectin benzoate (250g/ha) and for one of the tested bio‐insecticides, spinosad (30cc/hl) respectively. An increase of the total fresh mint weight compared to the non‐treated control was recorded for these three insecticides with 50.9%, 48.4%, and 40.5% for emamectin benzoate, chlorantraniliprole, and spinosad respectively. Insecticides containing chlorantraniliprole, emamectin benzoate, or spinosad active substances could be used as alternatives to other synthetic broad‐spectrum insecticides commonly used on spearmint in Morocco.     

Forensic pathology of canadian bread wheat: the case of tan spot

ABSTRACT Pyrenophora tritici-repentis causes necrosis and chlorosis in its wheat host. Susceptibility to races 2 (necrosis) and 5 (chlorosis) of the pathogen is known to be mediated by Ptr ToxA and Ptr ToxB, respectively. Sensitivity to each toxin is controlled by a single dominant and independently inherited gene. We used sensitivity to Ptr ToxA and Ptr ToxB as two genetic markers to investigate the origin and the state of tan spot susceptibility in Canadian Western Red Spring (CWRS) wheat over a period of more than a century. Sensitivity to Ptr ToxA, the toxin produced by nearly all isolates of the pathogen collected in the past 20 years in western Canada, appears to have been present in the first major cultivar, Red Fife, grown massively in the late 1800s. Sensitivity then was transmitted unknowingly into Canadian wheat lines through extensive use of backcrossing to maintain the Marquis-Thatcher breadmaking quality. Sensitivity to Ptr ToxA, which nearly disappeared from cultivars grown in western Canada in the 1950s, was reintroduced in the 1960s and unintentionally bred into many of the present-day cultivars. Sensitivity to Ptr ToxB, a toxin rarely found in isolates from western Canada, appeared with the release of Thatcher in 1934 and was transferred to many cultivars through backcross programs. In spite of large areas planted to Ptr ToxAand Ptr ToxB-sensitive cultivars over decades, tan spot epidemics remained sporadic until the 1970s. The results of this study raise the problem of the narrowing genetic base of CWRS wheat lines and the potential for unanticipated threats from plant pathogens. The intercrossing of genetically diverse material in one Canadian wheat breeding program resulted in the release of several modern cultivars with resistance to tan spot. The absence of wild-type Ptr ToxB-producing isolates in western Canada remains unexplained, given that sensitivity to Ptr ToxB was present continuously in western Canadian cultivars grown on vast areas for more than 70 years.     

Saffron as a source of novel acetylcholinesterase inhibitors: molecular docking and in vitro enzymatic studies

Inhibitors of acetylcholine breakdown by acetylcholinesterase (AChE) constitute the main therapeutic modality for Alzheimer's disease. In the search for natural products with inhibitory action on AChE, this study investigated the activity of saffron extract and its constituents by in vitro enzymatic and molecular docking studies. Saffron has been used in traditional medicine against Alzheimer's disease. Saffron extract showed moderate AChE inhibitory activity (up to 30%), but IC(50) values of crocetin, dimethylcrocetin, and safranal were 96.33, 107.1, and 21.09 μM, respectively. Kinetic analysis showed mixed-type inhibition, which was verified by in silico docking studies. Safranal interacts only with the binding site of the AChE, but crocetin and dimethylcrocetin bind simultaneously to the catalytic and peripheral anionic sites. These results reinforce previous findings about the beneficial action of saffron against Alzheimer's disease and may be of value for the development of novel therapeutic agents based on carotenoid-based dual binding inhibitors.     

Effect of ammonium or nitrate nutrition on photosynthesis,growth, and nitrogen assimilation in tomato plants

Nitrogen (N) is taken up by most plant species in the form of nitrate (NO ) or ammonium (NH ). Plant response to continuous NH nutrition is species‐dependent. In this study, we compare the responses of tomato (Solanum lycopersicum L. cv. Rio Grande) plants to N source (NO or NH ). To this end, early plant growth, photosynthesis, chlorophyll, carbohydrate, and N‐compound concentrations as well as the activities of main enzymes involved in N metabolism (nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate dehydrogenase) were analyzed. Early plant growth was remarkably ameliorated under NH ‐ in comparison to NO ‐based nutrition. Concomitantly, photosynthetic activity, total chlorophyll, and carbohydrate concentrations were significantly increased. With increasing external NH concentration, NH accumulated mainly in roots. In addition, root protein concentration was significantly increased, reflecting high NH incorporation into organic nitrogen. Root glutamine synthetase (GS) activity was enhanced by NH for concentrations below 5 mM, whereas root glutamate dehydrogenase (GDH) activity increased in parallel to NH availability. Together with the positive effect of NH on tomato plant cv. Rio Grande growth, these results reveal that GDH could have, in addition to GS, a possible role in NH detoxification and tolerance of NH ‐based nutrition.     

The Identification of Two New Races of Pyrenophora tritici-repentis from the Host Center of Diversity Confirms a One-to-One Relationship in Tan Spot of Wheat

ABSTRACT Pyrenophora tritici-repentis, causal agent of tan spot, induces necrosis and chlorosis in its wheat host. The tan spot system conforms to the toxin model and three host-specific toxins have been identified (Ptr ToxA, Ptr ToxB, and putative Ptr ToxC). Processing of a collection of isolates, obtained in the Fertile Crescent and Caucasus regions, yielded two new virulence patterns. Isolate Az35-5 combined the virulences of races 2 and 5 and was classified in the new race 7. Isolates TS93-71B and TS93-71F had a virulence pattern that combined those of races 2, 3, and 5 and were grouped in the new race 8. Southern analysis revealed that all three isolates possessed copies of the ToxA and ToxB genes, the first time the genes were found in a common background. The production of Ptr ToxA and Ptr ToxB by the isolates was confirmed by western blotting. Virulence patterns suggested that TS93-71B and TS93-71F may also produce Ptr ToxC, even though it was not present at detectable levels in culture filtrates. The identification of races 7 and 8 complete the theoretical maximum number of races that can be differentiated by three loci in the host (2(3) = 8), assuming a one-to-one relationship. It appears that the wheat/P. tritici-repentis system is a mirror image of the classical gene-for-gene relationship.