Effect of initial darkness duration on the pathogenicity of Calonectria pseudonaviculata on boxwood

Light is an important environmental stimulus that regulates many physiological activities within plants and pathogenic fungi. Boxwood blight (causal agent: Calonectria pseudonaviculata) is a newly emergent disease in the United States and a significant threat to the boxwood industry. A disease‐forecasting model has been developed to aid boxwood growers in their management decisions, but light is not included as a variable within the programme. Growth chamber experiments were conducted to evaluate the effect of an initial dark period on disease severity, mycelial growth and conidial germination of C. pseudonaviculata. Treatments varied by darkness duration (0, 6, 12 or 24 h dark), and were followed by a 14 h day length at a 25/21 °C day/night temperature. Neither boxwood blight severity nor fungal colony development was enhanced by an initial dark period. However, darkness duration was associated with a significant increase in conidial germination in vitro. This study suggests the predictive performance of the current boxwood blight disease‐forecasting model would not be improved by inclusion of photoperiod.     

Changes in micro- and macronutrient composition of pearl millet and white sorghum during in field versus laboratory decortication

Traditional decortication of pearl millet and white sorghum by hand pounding or using a mechanical device were performed in Burkina Faso, and compared to abrasive decortication in the laboratory using the same kernel lots. Using some nutrients as histological markers, the decortication characteristics and nutritional composition (iron, zinc, phytates, lipids, ADF fibres and starch) of decorticated grains were measured. Decortication had numerous effects on grain composition but no significant differences were observed between the two traditional methods of decortication. The effects varied according to the type of grain mainly due to the fact that more germ was removed in sorghum than in millet, as the millet germ is more embedded in the endosperm. During abrasive decortication, zinc and lipid losses increased rapidly due to removal of the germ, particularly in sorghum. Phytates were shown to be located mainly in the bran and germ but also in the endosperm in millet. In both sorghum and millet, half the iron was removed when only 10% of grain DM was abraded. The method of decortication, shock or friction vs. abrasion, influenced the fractions removed and thus the chemical composition of the decorticated kernels.     

Cumulative effects of forestry on habitat use by gray wolf (<Emphasis Type="Italic">Canis lupus</Emphasis>) in the boreal forest

Forest harvesting involves the creation of roads and cutblocks, both of which can influence animal habitat use. We evaluated the cumulative effects of forestry on habitat selection by six packs of gray wolf (Canis lupus) widely distributed in Quebec’s boreal forest. Resource selection functions were used to evaluate cumulative effects at two levels. First, we studied how the response of wolves to roads and cutblocks varied within their home range (HR level) as a function of the local abundance of these habitat features. Second, we assessed whether differences in the response to roads and cutblocks observed among packs (inter-HR level) could be explained by variations in their average abundance among individual home ranges. At the HR level, we found that cumulative effects shaped habitat selection of wolves, and the nature of the effects varied during the year. For example, we detected a decrease in the selection of roads following an increase in local road density during the rendez-vous and the nomadic periods, but not during the denning period. At the inter-HR level, we found a functional response to logging activity only during the denning period. Packs with home ranges characterized by a larger proportion of recent cutblocks selected these cutblocks more strongly. We conclude that cumulative effects of logging activities occur at multiple levels, and these effects can have profound effects on habitat use by wolves, thereby influencing spatial predator–prey dynamics. Wildlife conservation and management in boreal ecosystems should thus account for cumulative impacts of anthropogenic features on animal distribution.     

Use of ISSR markers to assess genetic diversity of African edible seeded Citrullus lanatus landraces

We used the twenty primers to evaluate the genetic variability of 80 individuals belonging to four accessions of edible seeded Citrullus lanatus originated from Côte d’Ivoire. Edible seeded C. lanatus, named “egusi” or “pistachio”, had a great importance in nutrition in West Africa. Nevertheless, due to its neglected status no study to our knowledge has been devoted to its genetic variability using DNA markers. The twenty ISSR primers generated 258 bands among which 252 were polymorphic (97.67%). On the whole, the bands generated revealed three types of profile sharply distinct from each other with minor differences within each type. One profile (P1) was most frequent with 65 individuals. Three accessions (NI084, NI127 and NI145) generated the three types of profile and had medium values of genetic diversity (GD = 0.246–0.275, respectively). On the opposite, the accession NI076 only contained individuals of the most represented type of profile (P1) and had the lowest genetic diversity (GD = 0.055 ± 0.017). The pairwise genetic distance between the 80 individuals varied from 0 to 0.61. The Factorial Component Analysis and the dendrogram clearly separated the 80 individuals into three clusters corresponding to the three types of profile. The results showed that clusters were well separated from each other whereas accessions were not. Our results suggest that high number of individuals should be taken into account for sampling missions and conservation strategies because accessions were not well differentiated from each other. Local agricultural practices consisting of frequent seeds exchanges between farmers and the conservation of harvested seeds for next year culture could be one explanation.     

Action of some herbicides on growth,respiration, plasmalemma integrity,and proton extrusion of Acer pseudoplatanus cells: I. Substituted ureas

The activity of 23 substituted ureas was assayed on nonphotosynthetic Acer pseudoplatanus cells, in batch suspension culture. They inhibited growth, stimulated oxygen consumption of cells, and caused a change in the pH of the culture medium. Some substituted ureas could modify the membrane permeability to protons, whereas some others could change the membrane permeabilities to ions and neutral solutes.     

Feline Langerhans cells migrate from skin and vaginal mucosa to regional lymph nodes during experimental contact sensitization with fluorescein isothiocyanate

Recently, feline Langerhans cells (LC) were immunophenotypically characterized as CD1a+, CD4+, CD18+, CD53+ and MHC II+ cells. In mice, these cells are known to internalize antigens and to migrate to the lymph nodes (LN). In the cat, we have investigated the migration of LC from the skin and vaginal mucosa to regional LN in response to chemical exposure (fluorescein isothiocyanate). Three days after the administration of a FITC solution on the posterior limb of two male cats and in the vagina of one female, a biopsy was carried out on the draining LN of the sensitized zones. Immunostaining with monoclonal antibodies anti-CD79, anti-CD8, and antibodies recognizing LC was performed on cytospins and frozen sections of LN and showed that a majority of FITC+ cells displayed a LC immunophenotype and were localized in T-cell areas, but not in follicular areas. These results are the first evidence of migration of feline LC from skin and vaginal mucosa to the regional LN.     

In vitro antimicrobial activity of orbifloxacin against Staphylococcus intermedius isolates from canine skin and ear infections

The objective of the study was to evaluate the in vitro activity of orbifloxacin against Staphylococcus intermedius strains isolated in France from canine skin and ear infections. The minimum inhibitory concentrations (MICs) of orbifloxacin against 240 field S. intermedius isolates (69 skin and 171 ear isolates) ranged from 0.016 to 8 mg l(-1), with MIC50 and MIC90 equal to 0.5 and 1 mg l(-1), respectively. Only one strain, a pyoderma isolate was resistant (MIC=8 mg l(-1)). Orbifloxacin was tested at different concentrations for killing rate against five isolates obtained from pyoderma cases and against a reference strain (Staphylococcus aureus ATCC 29213). Orbifloxacin expressed a concentration-dependent bactericidal activity against the S. aureus reference strain, but a time-dependent bactericidal activity against S. intermedius. Orbifloxacin induced bactericidal effect against the S. intermedius strains tested with concentrations equal to or two times MIC.     

A new irregular diterpenoid from Opopanax chironium

The ethereal extract of the roots of Opopanax chironium yielded peucelinenoxide acetate (1), a new natural product with an irregular diterpene skeleton, besides the known coumarins gaudichaudin, columbianadin, peucedanin and officinalin isobutyrate.