A method for developing a large-scale sediment yield index for European river basins

Background, aim, and scope  

Sediment fluxes within continental areas play a major role in biogeochemical cycles and are often the cause of soil surface degradation as well as water and ecosystem pollution. In a situation where a high proportion of the land surface is experiencing significant global land use and climate changes, it appears important to establish sediment budgets considering the major processes forcing sediment redistribution within drainage areas. In this context, the aim of this study is to test a methodology to estimate a sediment yield index at a large spatial resolution for European river basins.     

Resistance to late blight and soft rot in six potato progenies and glycoalkaloid contents in the tubers

Glycoalkaloids are anti-nutritional compounds commonly found in wildSolanum species used as resistance sources to major potato pathogens. It is therefore important for breeding purposes to know whether selecting for resistance using such species necessarily selects also for high glycoalkaloid contents in the tubers. To test this hypothesis, we used six partial progenies from crosses betweenSolanum tuberosum and accessions ofS. andigena, S. berthaultii, S. phureja, andS. vernei to investigate the possible correlation between resistance toPhytophthora infestans and/or toErwinia carotovora subsp.atroseptica and the concentration of glycoalkaloids in tubers. Concentrations of α-solanine and α-chaconine in the tubers segregated in each progeny, as did resistance to each pathogen. Some, but not all, clones from each progeny showed hypersensitive reactions to the isolate ofP. infestans used. Furthermore, clones within each progeny also differed for components of partial resistance toP. infestans, suggesting that all four wild species could be used as sources of both race-specific and partial resistance to late blight. With the exception of low, but statistically significant, correlations between concentration of α-solanine and two late blight resistance components (incubation period and spore production per unit lesion area) in progenies derived fromS. vernei, and despite a trend towards higher glycoalkaloid concentrations in the tubers of the clones most resistant to soft rot within progenies derived fromS. berthaultii andS. vernei, no consistent relationship between resistance to either disease and concentrations of α-solanine and/or α-chaconine was observed. These results indicate that neither race-specific nor partial resistance to late blight and soft rot in the accessions used as progenitors of resistance depend on high solanine or chaconine concentrations. These resistance sources could thus prove useful in breeding programs for improved behaviour againstP. infestans and/orE. carotovora.     

Recognition of H-2 types in relation to the blocking of pregnancy in mice

Inbred BALB/c females were mated and subsequently exposed in a divided cage to "stimulus" males or females whose H-2 type was similar or dissimilar to the stud male's. The incidence of pregnancy blocking was considerably higher when stud and stimulus males differed in H-2 type than when they did not. Similar results were obtained with urine samples of H-2 identical and nonidentical males. Females exposed after mating to other females whose H-2 type differed from the stud male, under the same experimental conditions, also showed an appreciable incidence of pregnancy block. It is therefore concluded that chemosensory recognition of H-2 types affects the reproductive hormonal status of the pregnant female.     

(E)-Methylisoeugenol and elemicin: antibacterial components of Daucus carota L. essential oil against Campylobacter jejuni

The essential oil of wild Daucus carota L. obtained from aerial parts at the end of the flowering stage (DCEO) was reported as antimicrobial against the human enteropathogen Campylobacter jejuni. The aim of the present study was to extend this analysis to other Campylobacter species and to identify the active compounds of the essential oil, subjected to GC, GC-MS, and (13)C NMR analysis. A minimum inhibitory concentration assay was used to quantify the antimicrobial activity of DCEO and the major components, isolated on column chromatography. Growth of all the C. jejuni, Campylobacter coli, and Campylobacter lari strains tested, including one multidrug resistant C. jejuni, was inhibited to the same extent by DCEO. Molecules that were responsible for the antibacterial activity were identified as (E)-methylisoeugenol and elemicin. Moreover, the use of structural analogues of these compounds allowed us to identify important features that may account for the activity.     

Morphological and molecular diversity within Algerian cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.) landraces

Twenty landraces of cowpea (Vigna unguiculata (L.) Walp.) scattered throughout Algeria were compared through morphological and genetic characterization. At the morphological level, for qualitative characters there was no intra-landrace variation and for quantitative characters the variations were low except for landrace NAG2 Three different cultigroups were located in Algeria: Biflora that was dominant in the Sahara, Melanophtalmus in the North and Unguiculata including one landrace in Kabylia and two in Sahara. The AMOVA analysis indicated that the genetic variation was lower within than among agro-ecological regions. A Mantel test, revealed a correlation between the qualitative morphological data and the geographical data (R = 0.28; P < 0.01), indicating that the degree of morphological change among landraces was roughly proportional to the geographical distances separating them. Genetic diversity was analyzed by using 11 random amplified polymorphic DNA (RAPD) and 12 inter-simple sequence repeat (ISSR) markers. No intra-landrace variability was found. The eleven RAPD primers yielded 77 bands, of which 45 (58.44%) were polymorphic; the genetic similarity ranged from 66.0 to 96.7%. The twelve ISSR primers provided a total of 104 bands, of which 65 (62.5%) were polymorphic; the genetic similarity ranged from 62.8 to 97.8%. cluster analysis showed a good match between genetic background and geographical distribution, which was confirmed by the results of the Mantel test. In particular, geographical data and genetic data were found to be correlated: (R = 0.33; P < 0.01) for RAPD, (R = 0.37; P < 0.01) for ISSR, and (R = 0.33; P < 0.01) for a combined RAPD-ISSR dataset. Moreover, despite the absence of significant correlation between morphological and RAPD data (R = 0.14; P = 0.14), significant correlations between morphological data and both ISSR (R = 0.27, P < 0.05) and a combined RAPD-ISSR dataset (R = 0.22, P < 0.05) were noted. ISSR markers were better linked to morphological variation than were RAPD markers. However, despite this, genetic distances among these landraces were found to be essentially the same no matter which markers were used.     

Influence of the Iron-Reducing Bacteria on the Release of Heavy Metals in Anaerobic River Sediment

The impact of autochthonous anaerobic bacteria on the release of metals in river sediment was studied. The sediments were characterized and bacterial activity was monitored in a batch reactor, where the sediments were incubated with a synthetic substrate solution containing glucose as carbon source. The results showed that metal release was correlated to the bacterial growth (carbon mineralization). In particular, a relationship between iron reduction and metal release was observed indicating that iron-reducing bacteria had a strong influence. By reductive dissolution of iron oxides, bacteria also released their associated toxic elements into the liquid phase. While organic analysis showed acetate and butyrate production leading to a decrease in pH and indicating a Clostridium fermentative bacteria activity, the results did not indicate any direct role of organic acids in the dissolution of iron and their associated metals.     

Antiproliferative activity of violaxanthin isolated from bioguided fractionation of Dunaliella tertiolecta extracts

Dunaliella tertiolecta (DT) was chemically investigated to isolate molecules inhibiting cancer cell proliferation and inducing apoptosis in vitro. The potency to inhibit cell growth was used for the bio-guided fractionation and isolation of active compounds using chromatographic techniques. The DT dichloromethane extract exhibited a strong anti-proliferative activity on MCF-7 and LNCaP cells, and was further fractionated and sub-fractionated by RP-HPLC. High resolution mass spectrometry and spectrophotometric analysis unequivocally identified violaxanthin as the most antiproliferative molecule present in DT DCM extract. Violaxanthin purified from DT induced MCF-7 dose-dependent growth inhibition in continuous and discontinuous treatments, at concentrations as low as 0.1 μg·mL⁻¹ (0.17 μM). Phosphatidylserine exposure, typical of early apoptosis, was observed after 48 h treatment at 8 μg·mL⁻¹ (13.3 μM) but no DNA fragmentation, characteristic of late apoptosis steps, could be detected even after 72 h treatment at 40 μg·mL⁻¹ (66.7 μM). Taken together, our results demonstrate the strong antiproliferative activity of violaxanthin on one human mammary cancer cell line, and suggest that studying the pharmacology of violaxanthin and pharmacomodulated derivatives on cancer cells may allow potent antiproliferative drugs to be obtained.     

Familial imprinting determines H-2 selective mating preferences

Inbred male mice typically prefer to mate with females of a different, non-self H-2 haplotype. To determine whether this natural preference is irrevocable or results from familial imprinting, a test system was used which relied on previous observations that B6 males (H-2b) mate preferentially with congenic B6-H-2k rather than B6 females, and B6-H-2k males with B6 females. This preference was reversed in B6 males fostered by B6-H-2k parents and in B6-H-2k males fostered by B6 parents, preference in these cases favoring the same H-2 type. Thus, H-2 selective mating preference is acquired by imprinting on familial H-2 types.     

Effect of prolonged cold storage on the production capacity of strawberry plants

After cold storage for various periods (42, 99, 155, 189, 227 and 259 days) strawberry waiting-bed plants cultivar ‘Elsanta’ were planted on six dates between January and August. Plant performance was evaluated simultaneously in a growth chamber under controlled environmental conditions and in a greenhouse. Starch content in the crown tissue was clearly reduced during the cold storage period.

In the greenhouse trials a variable decline in fruit number and yield per plant was found in relation to the length of cold storage and the temperature conditions during the growth and harvest period. Also in the growth chamber, under a constant temperature regime, a significant decline in the number of flowers per plant developing up to anthesis was observed after increasing periods of storage. This indicates that it is not only stressing climatical conditions after planting which are influencing the performance of cold stored plants. Also, the length of cold storage strongly affects plant vigour and productivity. This is related to the carbohydrate status of the plants after cold storage.