Effects of associated fungi Sclerophoma pythiophila and Cenangium ferruginosum on Gremmeniella abietina dieback in Spain

The interactions between Gremmeniella abietina and either Sclerophoma pythiophila or Cenangium ferruginosum, fungi frequently isolated from diseased twigs along with G. abietina, were studied under laboratory (dual cultures) and greenhouse conditions (double‐inoculations). Virulence of each species was also evaluated in greenhouse experiments by means of single‐inoculations. In vitro interactions were assessed on Petri dishes containing malt agar with pine needle extract, and greenhouse experiments were performed on 1‐year‐old Pinus halepensis seedlings. In vitro growth of G. abietina was inhibited by both fungi when grown in dual culture. In single‐inoculations, G. abietina caused the greatest necrosis length on P. halepensis seedlings, followed by S. pythiophila, whereas C. ferruginosum did not cause significant necrosis. In double‐inoculations, C. ferruginosum was able to reduce the length of necrosis caused by G. abietina on the P. halepensis seedlings. In contrast, necrosis length was greater in seedlings inoculated with both S. pythiophila and G. abietina than in those inoculated with G. abietina alone. Therefore, S. pythiophila seems to play a role in disease expression caused by G. abietina on P. halepensis in Spain.     

Variation in pathogenicity among the three subspecies of Phytophthora alni on detached leaves,twigs and branches of Alnus glutinosa

Pathogenicity tests were carried out on leaves, twigs and branches of Alnus glutinosa using several isolates of Phytophthora alni ssp. alni, P. alni ssp. multiformis and P. alni ssp. uniformis in vitro. Healthy fresh leaves were collected from disease‐free areas and inoculated with mycelium on agar discs or by dipping in zoospore suspensions. In addition, twigs and branches were collected from both disease‐free and disease‐affected areas, inoculated with mycelium on agar discs and incubated at four temperatures (15, 20, 25, 30°C). All subspecies tested were pathogenic but with varied level of virulence. In inoculation tests on foliage, wounding was a key factor in causing infections: lesions on inoculated wounded leaves were larger than on non‐wounded leaves. In the twig and branch inoculation tests, no differences in virulence were observed among the P. alni subspecies in terms of sampling locations, but lesions differed in size according to incubation temperature, with the largest lesions occurring on tissues incubated at 25°C. The work is the first to report foliar necrosis caused by P. alni on A. glutinosa. P. alni ssp. uniformis was the least virulent of the subspecies in branch inoculations. These findings demonstrate that various tissues of A. glutinosa could act as sources of pathogen inoculum and may disseminate alder Phytophthora in natural ecosystems.     

Cytoprotection by neutral fraction of tannat red wine against oxidative stress-induced cell death

Some of the beneficial effects of the Mediterranean diet on human pathologies have been attributed to red wine polyphenols. It has been postulated that the antioxidant activity of the latter would be also responsible for the cytoprotective capacity of red wine that has been reported in a few papers. Nevertheless, red wine shows a complex composition, and the active fraction is not known yet. In this context, the protective capacity of total lyophilized extracts of red wine and anthocyanin, neutral, or acidic fractions, was explored in PC12 cells in culture after a hydrogen peroxide insult. Although all fractions showed high antioxidant activity, only the neutral fraction was cytoprotective. The analysis of this active fraction showed that it was rich in the aglycons quercetin and myricetin as well as the glycosides of kaempferol, isorhamnetin, epicatechin, and catechin, some of which are known to be cytoprotective. This is the first paper to reveal the active fraction of total wine responsible of its cytoprotection.     

A G protein mutant that inhibits thrombin and purinergic receptor activation of phospholipase A2

The stimulation of phospholipase A2 by thrombin and type 2 (P2)-purinergic receptor agonists in Chinese hamster ovary cells is mediated by the G protein Gi. To delineate alpha chain regulatory regions responsible for control of phospholipase A2, chimeric cDNAs were constructed in which different lengths of the alpha subunit of Gs (alpha s) were replaced with the corresponding sequence of the Gi alpha subunit (alpha i2). When a carboxyl-terminal chimera alpha s-i(38), which has the last 38 amino acids of alpha s substituted with the last 36 residues of alpha i2, was expressed in Chinese hamster ovary cells, the receptor-stimulated phospholipase A2 activity was inhibited, although the chimera could still activate adenylyl cyclase. Thus, alpha s-i(38) is an active alpha s, but also a dominant negative alpha i molecule, indicating that the last 36 amino acids of alpha i2 are a critical domain for G protein regulation of phospholipase A2 activity.     

Effect of dose and type of fertilizer on flowering and fruiting of vanilla plants

Nutritional status affects the processes of flowering and fruiting of plants. This study was conducted to determine the effects of fertilizer application on flowering, fruiting, and leaf nutrient content of Vanilla planifolia (Jacks. ex Andr). Treatments consisted of the application of grade 10-20-20 nitrogen, phosphorus, and potassium (NPK) fertilizer to the substratum in annual doses of 20, 50, and 100 g/plant plus a monthly application of foliar fertilizer. Two more treatments were foliar fertilization and no fertilization (control). Treatments increased the number of inflorescences and flower buds per plant, as well as the number and weight of fruits per plant, and decreased the abortion of flowers and immature fruits. These effects depended on the type of fertilizer, the amount applied, and the time of evaluation. The best results were obtained with the 100 g/plant/year treatment with an annual production of 1.5 kg of fruits per plant in the second year. Unfertilized plants produced 0.55 kg/plant/year. Differences were also found in foliar content of N, P, K, and copper (Cu) between vegetative and reproductive branches. Application of fertilizer to the substratum appears to improve reproductive parameters of vanilla plants and the production of beans, while foliar fertilization alone was ineffective in increasing crop productivity. Nutrients also seem to translocate from mature leaves to fruit racemes.     

Prediction of protein digestibility in dog food by a multi-enzymatic method: a useful technique to develop

The multi-enzymatic method with constant pH described by Dufour-Etienne et al. (Rec. Méd. Vét. 168 , 789–796, 1992) was tested using 17 industrial dry dog foods and two ingredients, sodium caseinate and beef meat, which were used as references. The quantity of sodium hydroxide added to the enzymatic solution was measured after incubation times of 2, 5 and 10 min and the best prediction of the apparent protein digestibility was obtained with an incubation time fixed at 2 min. The volume of sodium hydroxide 0.1 N constantly added to maintain the pH of the solution at 8 was correlated to the value of in vivo digestibility of the protein measured in the dog. The correlation coefficient obtained was 0.90 with a standard error of the regression of 1.9 for all samples. The correlation coefficients calculated for incubation times of 5 and 10 min were lower than that at 2 min; thus an incubation period of 2 min provided the highest correlation coefficient for this multi-enzymatic method at constant pH. However, considering the lack of samples with an apparent protein digestibility ranging between 85 and 95%, the slope of the regression line and the correlation coefficient were strongly influenced by the ingredients, such that when the correlation coefficient was calculated for 17 dog foods without the reference ingredients, a coefficient of 0.71 (± 1.9) was obtained. These tests of in vitro digestibility are valuable to predict the apparent digestibility of the protein in the dog, but, it is essential to confirm the results by an in vivo test.     

Diversity of Cryphonectria parasitica in western Spain and identification of hypovirus‐infected isolates

Isolates of the chestnut blight fungus Cryphonectria parasitica were obtained from 44 localities in four provinces in Western Spain and characterized for vegetative compatibility (vc) types, mating types and the presence of Cryphonectria hypovirus 1 (CHV1). Among the 1232 isolates recovered from chestnut blight cankers, 11 vc types were identified: five known vc types included in EU1 to EU74 (EU1, EU11, EU12, EU28 and EU66) and six unknown vc types (CL4, CL5 CL6, CL8, CL9 and CL10). The number of vc types found per province varied between two and seven. The vc type EU11 was present in all provinces and accounted for 48.9% of all isolates. EU1 was detected in three provinces and accounted for 39.1% of the isolates. The vc types EU12, EU66, CL5 and CL6 were present in one or two provinces and comprised between 2.4% and 3% of the isolates. The other vc types were represented by only one or very few isolates. The mating type MAT‐1 was largely dominant in the provinces Leon and Avila, while both mating types MAT‐1 and MAT‐2 were found in Salamanca and Zamora. Fourteen hypovirus‐infected C. parasitica isolates were found, nine were in vc type EU1 and five in EU11, and they were detected only in the province León. All isolates analysed contained the French hypovirus subtype CHV1‐F1.