Differential flood stress resistance of two almond cultivar* based on survival,growth and water relations as stress indicators

SUMMARY

Potted almond trees (Amygdalus communis L.) of the two cvs Ramillete and Garrigues were submitted to two treatments: non-flooded (control) and flooded for 7 d in June 1991 under field conditions. After being submerged for one week, the almond trees were removed from the water (recovery period). The effects of flooding on the growth, stomatal behaviour, leaf water potential, osmotic potential and turgor potential were examined through the experimental period. Flooding caused a reduction in root dry weight of 'Ramillete', wilting, chlorosis and necrosis of the leaves, and plant death. Epinasty occurred in treated trees, but it appeared sooner in 'Garrigues' than in 'Ramillete'. Garrigues presented the lower resistance of plant plus soil (R(p+S)) for both treatments. After the flooding period, a progressive reduction of R(p+S) values was noted in 'Garrigues'. The decrease in leaf water potential by flooding in both cultivars can be related to an increase in the resistance to water uptake. Leaf osmotic and turgor potential behaviour confirm the progressive dehydration of leaf tissues. The continous decrease in v|/" \ys and values in 'Ramillete' indicated that the severity of the damage induced by flooding stress was irreversible in this cultivar. The reduction in leaf conductance (g,) can be related to the leaf water deficit by effects of flooding, the recovery of g, for 'Garrigues' occurred 20 d after leaf water potential. The differences between the cultivars suggest that they differ in their ability to withstand flood conditions and their association is not desirable in poorly drained soils.     

Effects of logging on orangutan behavior

The human footprint is increasing across the world’s natural habitats, causing large negative impacts on the survival of many species. In order to successfully mitigate the negative effects on species’ survival, it is crucial to understand their responses to human-induced changes. This paper examines the effect of one such disturbance, logging, on Sumatran orangutans – a critically endangered great ape. Orangutan population densities may decrease or remain stable after logging, but data on the effects of logging on the behavior of individuals is scant. Here, we provide individual-level behavioral data based on direct observations in 2003–2008 at the Ketambe (Sumatra, Indonesia) research area (partly subject to intense selective logging) in order to assess responses of Sumatran orangutans to logging. Logging significantly negatively affected forest structure and orangutan food resources, specifically important fallback and liana-derived foods. Individual orangutans behaved differently between logged and pristine forest; they moved more and rested less in logged forest. With the exception of figs, diet composition remained overall similar. Altogether, life after logging seems energetically more expensive for orangutans. Based on the results of this study, we provide recommendations for conservation research and guidelines for reduced-impact logging.     

Effects of propiconazole on extra-cellular enzymes involved in nutrient mobilization during <Emphasis Type="Italic">Trametes versicolor</Emphasis> wood colonization

The effects of propiconazole on extra-cellular enzyme levels in Trametes versicolor have been investigated during wood colonization and degradation. The working hypothesis was that the biocide could alter metabolic pathways, which could lead to an alteration of extra-cellular enzyme production. In the presence of a propiconazole sub-lethal concentration, the wood degradation rate decrease concomitantly with the lag phase of fungal development observed during wood colonisation. The pattern of production of enzymes involved in polysaccharide degradation (β-glucosidases, glucuronidases, cellobiohydrolases), nitrogen (leucine aminopeptidase) and phosphorus (acid phosphatase) mobilization was only slightly altered in the presence of the biocide. In experiments performed in the presence of propiconazole, there was a strong induction of chitinases at the beginning of the colonization process. Addition of caffeine, a pleiotropic drug, which is also a chitinase inhibitor, together with propiconazole resulted in synergistic inhibition of the fungal growth. The implication of these results in the development of a new wood preservation strategy is discussed.     

Enhanced excretion of DDT and metabolites in rats treated with trans,trans-muconate

The interactions between trans,trans-muconate and p,p′-DDT were examined. Male Wistar rats were injected intraperitoneally with 6.67 mg kg^?1 [¹⁴C]p,p′-DDT. Two hours later the experimental animals received orally a solution of sodium muconate (75 mg kg^?1, 0.3 ml) in physiological saline, pH 7.2; control animals received an equal volume of physiological saline. Treatment was repeated every 12 hr for 10 days. Sodium muconate does not modify urinary excretion of labeled compounds, yet it reduces body burden by accelerating the excretion rate of these compounds in rat feces. This action was observed only during the first 24 hr after the animals were exposed to p,p′-DDT.     

Cross-protection of Salmonella abortusovis, S. choleraesuis, S. dublin and S. gallinarum in mice induced by S. abortusovis and S. gallinarum: bacteriology and humoral immune response

Cross-protection induced by primary infection with Abortusovis and Gallinarum was examined against challenge injection with these Salmonella serotypes as well as with Dublin and Choleraesuis, the other virulent serotypes. Abortusovis induced efficient protection against the other Salmonella. Gallinarum was ineffective against Choleraesuis. Even with low multiplication in mice, the Gallinarum J91 strain induced a weak but significant protection against Dublin (same O group serotype). The antibodies in the blood of mice were tested with ELISA specific for the Salmonella antigens used to prime or to challenge animals. The Gallinarum J91 strain was detected to be more antigenic in ELISA than the other Salmonella antigens. It is difficult to conclude on a correlation between IgM or IgG antibodies and induction of protection, because of the variability in immune response according to the different serotype used. Nevertheless, the negative linkage between a number of bacteria in the spleen of mice challenged with Gallinarum and Dublin, and the level of IgM and IgG antibodies specific for the challenging serotype, showed that humoral immune response could be one element of cross-protection, mainly by the immune response against the same O serotype.     

SLO angiography: arterio-venous filling times in monkey and minipig

Confocal scanning laser ophthalmosocope (cSLO) is a new technique which enables ocular fundus image recording and dynamic retinal angiography to be performed. The ocular fundus image is acquired sequentially, point by point, and is reconstructed on a video monitor at the rate of 25 images per second. The aim of this paper is to evaluate the feasibility of measuring retinal arterio‐venous filling times (AVFT) with a I + Tech cSLO. Three young adult cynomolgus monkeys and three young adult Göttingen minipigs were used as experimental models. All animals were anesthetized using a zolazepam + tiletamine mixture injected intramuscularly; heart rate and rectal temperature were monitored and corneal irrigation was regularly performed. For all subjects, prior to examination, hematocrit and globe axial length were measured. The images were recorded, stabilized and analyzed. The retinal examination consisted of retinal images with 40° field cSLO, retinal fluorescein angiography and arterio‐venous 50% filling time measurements. For each subject all images were easily recorded while keeping the animals in a normally lighted room without having to use any additional optical device. AVFT using an I + Tech cSLO is easily performed in monkeys and minipigs. AVFT measurements in minipigs and monkeys are similar. These results suggest that minipigs can replace monkeys as an experimental species for AVFT investigations.     

The effect of the mode of application on the toxicity of Androctonus australis hector insect toxin

The toxicity of the insect toxin from the venom of the scorpion Androctonus australis Hector (AaH IT) was assayed using several ethods of application on various insect species. Activity was only demonstrated by opical application on Musca domestica. Three different solvents were assayed: ethanol + water (50 + 50 by volume), acetone + water (80 + 20 by volume) and acetone + dimethyl sulphoxide (50 + 50 by volume). When using the last two mixtures, LD₅₀ was found to be 1 μg 100 mg^?1 fly. When this activity is compared to that of five synthetic insecticides tested in the same conditions, AaH IT is about 1-5 times more active than propoxur and DDT, 10 times more active than malathion but 200 times less active than deltamethrin. No activity was observed against Aphis craccivora at 15 mg m^?2 in surface-contact tests on glass, or against Culex pipiens pipiens larvae at 2 × 10⁵ ng litre^?1 in water.     

Soil Covers for Controlling Acid Generation in Mine Tailings: a Laboratory Evaluation of the Physics and Geochemistry

To evaluate the effectiveness of soil covers, column experiments were conducted on tailings protected by a three-layer soil cover and tailings directly exposed in the open laboratory for a period of 760 days. Periodic rain application was performed to simulate field conditions, and at four times during the experiments the pore water was completely flushed out of each column for analysis. Profiles of oxygen, temperature, and volumetric water content were measured throughout the experiment, and the post-testing pore water quality was also characterized. A one-dimensional semi-analytic diffusion model was used to simulate oxygen profiles in the uncovered tailings. Modelling performed using the geochemical code MINTEQ showed that in the laboratory, aluminium concentrations in the tailings pore water were controlled by Al(OH)SO₄, sulphate by gypsum and Al(OH)SO₄and iron by lepidocrocite in the upper half and by ferrihydrite in the lower half. In the field, however, the iron oxyhydroxide minerals formed in the oxidized zone appear to be dissolving. It was found that the cover was effective in preventing significant desaturation of the clay, even over a 150-day drying period. The covered tailings did not oxidize much during the experiments. In the uncovered tailings, oxygen modelling and examination of the geochemistry show that the rate of gross oxidation and the advancement of the oxidation front decreases with time. However, pore water quality is controlled by geochemical processes other than oxidation, as reported in the field.