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.     

Assessing solid waste compost application as a practical approach for salt-affected soil reclamation

Abstract

A short-term pot experiment was made to evaluate the effectiveness of municipal solid waste compost amendment on salt-affected soil. Hordeum maritimum plants were cultivated in pots filled with a clay-loam soil containing 0 or 40 t ha^?1 of compost and irrigated with tap water at 0 or 4 g l^?1 NaCl. Soil properties and heavy metal (Zn^{2 +}, Pb^{2 +}, Cd^{2 +}) accumulation were investigated. Municipal solid waste compost application significantly increased the soil contents of carbon, nitrogen and potassium under both non-saline and saline conditions. Soil heavy metal concentrations increased substantially too, but the recorded values were below the toxicity limits. Interestingly, plants subjected to the salt–compost interaction were more vigorous, compared with those grown on non-amended soil. Altogether, our data indicate that short-term utilization of municipal solid waste compost at 40 t ha^?1 may be of potential interest in the perspective of the rehabilitation of salt-affected soils. Yet, it must be stressed that the present findings are preliminary and need to be further evaluated under field conditions before practical recommendations can be inferred.     

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.     

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.     

Quantification of critical factors affecting fitness of the sugary1 mutant in maize

Fitness of sugary1 (su1) is affected by some critical traits that depend on the genotypes and environments, while their effects have not been quantified with convincing statistical methods. The objective of this work was to identify and quantify the critical factors of su1 fitness with different genotypes and environments. We used two pairs of field corn inbreds that differentially affected su1 viability to develop F₁, F₂, BC₁ and BC₂. After selfing, Su1 and su1 kernels were evaluated under controlled environmental conditions and in field trials. Multiple regressions showed that dry weight of juvenile plant was affected by early vigour (plant size, colour and health) and emergence in cold conditions; ear weight by plant appearance, number of plants and chlorophyll content; number of ears by plant appearance, number of plants, chlorophyll content and female flowering; and kernel weight by ear weight, number of plants, row number and ear length. The main critical factors for su1 fitness were early vigour and emergence under cold conditions at initial stages, while several adult traits were related with final fitness.     

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.     

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.     

Inheritance of Race-Specific Resistance to Mycosphaerella graminicola in Wheat

ABSTRACT Mycosphaerella graminicola causes Septoria tritici blotch of hexaploid and tetraploid wheat. The inheritance of high-level resistance to Septoria tritici blotch was studied in controlled environment experiments. Intraspecific reciprocal crosses were made between hexaploid wheat lines Salamouni, ST6, Katepwa, and Erik, and the tetraploid wheat lines Coulter and 4B1149. Parental, F(1), F(2), F(3), BC(1)F(1), and BC(1)F(2) populations were evaluated for reaction to isolates MG2 and MG96-36 of M. graminicola. Resistance was controlled by incompletely dominant nuclear genes in all cases. Salamouni had three independent resistance genes to isolate MG2, two of which also controlled resistance to isolate MG96-36. ST6 had a single resistance gene to isolate MG2 and none to isolate MG96-36. The resistance genes in Salamouni and ST6 were not allelic. Two independent genes control resistance to isolate MG2 in Coulter, one of which also controlled resistance to isolate MG96-36. These data are consistent with a gene-for-gene interaction in the wheat-M. graminicola pathosystem.