The breakage of dormancy in Datura ferox seeds as an effect of water absorption

Datura ferox seeds do not germinate when they are incubated intact and in darkness, even after 24 months of dry storage. If allowed to absorb water vapour for 3–4 weeks at 20°C, they lose dormancy, germinating even when incubated in darkness. The breakage of dormancy is directly related to the vapour pressure of the atmosphere where the seeds are stored, and good aeration is necessary for the process to occur. If seeds absorb liquid water, the toss of dormancy is much less than that of seeds stored in a saturated atmosphere. A similar effect is observed when seeds are buried in a soil at field capacity. The results indicate that a certain degree of imbibition, under good gas-exchange conditions, is important for breaking dormancy. As a hypothesis, it is proposed that most of the population remains dormant when not enough O₂ is available for (he imbibed seed. The low rate of O₂ entry could be due to poor diffusion through the water-saturated seed coat (seeds which absorb liquid water) or to a low O₂ level in the surrounding atmosphere (soil at field capacity). One of the possible roles of O₂ could be to oxidize the inhibitor(s) present in these seeds. La rupture de la dormance des semences de Datura ferox considérée comme un effet de l'absorplion de l'eau. Les semences de Datura ferox ne germent pas quand elles sont mises au germoir intactes et à l'obscurité, même aprés 24 mois de conservation au sec. Si elles peuvent absorber de la vapeur d'eau pendant 3 à 4 semaines à 20°C, elles perdent leur dormance et germent meme & à l'obscurité. La rupture de la dormance est en relation directe avec la pression de la vapeurd'eau de l'atmosphére dans laquelle les semences sont conservées; une bonne aération est nécessaire pour que le processus se déclanche. Si les semences absorbent de l'eau à l'état liquide, la rupture de dormance est beaucoup moindre que celle de semences conscrvées dans une atmosphére saturée. Un effet analogue est observé lorsque les semences sont ententes dans un sol ayant atteint sa capacity au champ. Les résultats indiquent qu'un certain degriS d'imbibition, sous de bonnes conditions d'changes gazeux. est important pour la rupture de la dormance. Comme hypothtése, il est proposé que la plus grande partie de la population reste dormante lorsqu'il n'y a pas assez d'oxygene disponible pour la semence imbibeée. Le faible taux d'absorption d'oxygéne pourrait étre du à sa fuible diffusion à travers l'enveloppe saturée d'eau de la semence (pour celles qui absorbent l'eau à I état liquide) ou à un bas niveau d'oxygene dans Tatmosphére environnante (cas d'un sol à la capacityé au champ). Un des rôles possibles de l'oxygéne pourrait être d'oxyder les inhibiteurs presents dans les semences. Das Brechen der Keimruhe in Samen von Datura ferox ah ein Effekt der Wasseraiifnahme Samen von Datura ferox keimen nicht, wenn sie bei Dunkelheit gehalten werden; auch nicht, wenn sie zuvor 24 Monate trocken lagerten. Wenn sie bei 20°C, 3 bis 4 Wochen tang Wasserdampf aufnehmen, verlieren sie die Keimhemmung und keimen sogar im Dunketn. Zwischcn dem Brechen der Keimruhe und dem Damptdruck der Luft in der sie gelagert werden, besteht eine direkte Beziehung. Fur diesen Vorgang ist eine gute BelCiflung Vorausselzung. Wenn die Samen flijssiges Wasser aufnehmen, ist der Verlust der Keimhemmung wesentlich geringer als wenn sie in einer gesättigten Atmosphäre gelagert werden. Eine ähnliche Wirkung wird beobachtet. wenn die Samen im Boden bei Feldkapazität gelagert werden. Die Ergebnisse zeigen, dass für das Brechen der Keimruhe ein bestimmtes Mass der Aufnahme bei ausreichendem Gasaustausch wichtig ist. Als cine Hypothese wird vorgeschlagen, dass die meisten der Population dormant bleiben, wenn für die mil Wasser vollgesaugten Samen nicht ausreichend O₂ verfügbar ist. Der geringe Zutritt an O₂ konnte auf die mässige Diffusion durch die wassergesättigte Samenschale (Samen die fliissiges Wasser aufnehmen), oder auf einen geringen O₂-Gehalt in der umgebenden Luft (Boden bei Feldkapazität) zurückzuführen sein. Eine der möglichen Bedeutungen die dem O₂ zukommen, könnte in der Oxidation des bzw. der Hemmstoffe der Samen liegen.     

Effects of supplemental feeding on gastrointestinal parasite infection in elk (Cervus elaphus): preliminary observations

The effects of management practices on the spread and impact of parasites and infectious diseases in wildlife and domestic animals are of increasing concern worldwide, particularly in cases where management of wild species can influence disease spill-over into domestic animals. In the Greater Yellowstone Ecosystem, USA, winter supplemental feeding of Rocky Mountain elk (Cervus elaphus) may enhance parasite and disease transmission by aggregating elk on feedgrounds. In this study, we tested the effect of supplemental feeding on gastrointestinal parasite infection in elk by comparing fecal egg/oocyst counts of fed and unfed elk. We collected fecal samples from fed and unfed elk at feedground and control sites from January to April 2006, and screened all samples for parasites. Six different parasite types were identified, and 48.7% of samples were infected with at least one parasite. Gastrointestinal (GI) nematodes (Nematoda: Strongylida), Trichuris spp., and coccidia were the most common parasites observed. For all three of these parasites, fecal egg/oocyst counts increased from January to April. Supplementally fed elk had significantly higher GI nematode egg counts than unfed elk in January and February, but significantly lower counts in April. These patterns suggest that supplemental feeding may both increase exposure and decrease susceptibility of elk to GI nematodes, resulting in differences in temporal patterns of egg shedding between fed and unfed elk.     

Closed fluoroscopic-assisted spinal arch external skeletal fixation for the stabilization of vertebral column injuries in five dogs

Objective— To evaluate outcome after closed fluoroscopic-assisted application of spinal arch external skeletal fixators in dogs with vertebral column injuries.
Study Design— Retrospective case series.
Animals— Dogs with traumatic vertebral column injuries (n=5).
Methods— Medical records of dogs with vertebral column fractures and/or luxations stabilized with spinal arch external skeletal fixator frames applied using a closed fluoroscopic-assisted technique were reviewed. Owners were contacted to obtain long-term clinical outcomes.
Results— Five dogs (age range, 6–72 months; weight, 10–54 kg) had traumatic vertebral column injuries stabilized with spinal arch external skeletal fixators applied in closed fashion. Injuries involved vertebral segments of the thoracolumbar junction, lumbar spine, and lumbosacral junction. Immediately postoperatively, 4 dogs had anatomic alignment of their vertebral fracture/luxation; 1 dog had 1 mm of vertebral canal height compromise. Time to fixator removal ranged from 65 to 282 days (141±87 days). All dogs had regained satisfactory neurologic function by 3 months. At long-term follow-up (range, 282–780 days; mean 445±190 days) all dogs were judged to have good to excellent return of function by their owners.
Conclusion— Successful closed fluoroscopic-assisted application of external skeletal fixators using spinal arches provided satisfactory reduction with few complications in 5 dogs. Return to function was judged to be good to excellent in all dogs at long-term evaluation.
Clinical Relevance— Closed fluoroscopic-assisted application of ESF using spinal arches provided satisfactory reduction and effective stabilization of spinal fractures with few complications and should be considered as a treatment approach.     

Regional differences in the in vitro penetration of methylsalicylate through equine skin

Commercial formulations of non-steroidal anti-inflammatory drugs (NSAIDs) are developed for human use but the extent to which they will pass through equine skin is unknown. Skin was harvested from five Thoroughbred geldings from the thorax, groin and leg (dorsal metacarpal) regions and frozen (-20 degrees C) until required. Two grams of methylsalicylate (MeSa) gel was applied to defrosted full-thickness samples in diffusion cells and the penetration of MeSa and its active metabolite, salicylate (Sa), through skin samples were measured over 24 h. Significantly higher (P < or = 0.02) total salicylate (AUC; MeSa + Sa) penetrated through skin from the leg region (5491.3 h mg/L), compared to thorax (3710.7 h mg/L) and groin (3571.5 h mg/L). In addition, there was a significantly higher (P0.01) rate of penetration of total Sa through leg skin in the first 6h after application. It was concluded that the commercial formulation of MeSa would achieve therapeutic levels of total salicylate beneath sites of topical application, with a faster and more pronounced response through the leg region, compared to the upper body.     

Capillary electrophoretic behaviour of humic substances from Sphagnum peats of various geographical origin: relation with the degree of decomposition

Humic substances (HS) extracted from 14 Sphagnum peats of various geographical origin were submitted tocapillary electrophoresis (CE) in free solution and in entangled polymer solutions (25 gl^-1 and 50 gl^?1) of polyethylene glycol (PEG). Electrophoretic runs were made in uncoated capillaries (75 μm internal diameter) using a tris-hydroxymethylaminomethane (TRIS)-phosphate buffer (pH 8.3) eventually containing PEG and applying a voltage of 10 kV. The HS extract of a Lithuanian peat was fractionated by ultrafiltration into five fractions with a nominal mean relative molecular mass (M) of 3000, 7500, 20 000, 75 000 and 200 000 Da. Without PEG, migration times were not correlated with the logarithm of M, but linear relations were obtained with 25gl^?1 and 50gl^?1 PEG solutions. Both solutions separated the different fractions by size; the best regression and the largest interval of linearity, M from 3000 to 200 000 Da, was obtained with the 25gl^?1 PEG solution. At 10kV and without PEG, migration times ranged from 6.5 to 8.1 min and did not differentiate the peats, whereas at 25gl^?1 PEG, migration times ranged from 3.3 to 6.5 min and, when plotted as a function of either the r value or the von Post index (H), which are used to evaluate the degree of decomposition of horticultural peats, they separated samples on the basis of their geographical origin and probable type of mire complex. At 25gl^?1 PEG, migration times also showed a well-defined linear decreasing trend with the increase of mean annual temperatures. These relations suggest the hypothesis that humification in mires goes along with an increase in the average size of humic molecules.     

Effects of dissolved organic matter on the mobility of copper in a contaminated sandy soil

Changes in land use can result in increased soil organic matter content, and decreases in Ca and pH which will affect the mobility of Cu in soil. We studied how the mobility and coagulation of dissolved organic matter and pH affected the mobility of Cu in contaminated sandy soil by batch and column experiments in the laboratory. The soil, with pH ranging from 3.8 to 5.7, had been polluted with Cu in the range 0.13–1.9 mmol kg^?1 more than a decade ago. Calcium and Cu bound by dissolved organic matter (purified humic acid) was determined in the pH range 4–8; Cu²⁺ concentration ranged from 10^?4 to 10^?12M and Ca²⁺ concentration from 10^?3 to 10^?6M. Binding of Cu by dissolved organic matter as affected by Ca and pH could be predicted well with the non-ideal competitive adsorption (NICA) model. Coagulation of dissolved organic matter was affected by the amount of trivalent (Al³⁺) and divalent (Ca²⁺ and Cu²⁺) cations in solution. There was little effect of pH on coagulation between pH 4 and 6. The concentration of the divalent cations, Ca²⁺ and Cu²⁺, at which coagulation of dissolved organic matter appeared could be explained by differences in the binding of Ca and Cu by dissolved organic matter. Binding of Cu by dissolved organic matter as well as by solid organic matter, both affected by Ca and pH, could be described well with the NICA model. We investigated the coagulation and mobility of dissolved organic matter in column experiments and found that they enhanced Cu mobility. Three processes, Cu desorption by soil, dissolved organic matter coagulation and Cu complexation by dissolved organic matter, act simultaneously in the soil columns. All three with counteracting effects on Cu mobility are influenced by Ca and pH and could be adequately represented by the multicomponent NICA model.     

Growth and metabolic responses of tambaqui (Colossoma macropomum) fed different levels of protein and lipid

Growth and metabolism were investigated in juvenile tambaqui (Colossoma macropomum) fed with isoenergetic diets in four treatments with protein (P) lipid (L) in g kg^?1: P350L49; P301L81; P253L113 and P205L145, respectively. The experiments were carried out in the laboratory facilities. Fish growth, the intermediary metabolites (total sugar, lactate, pyruvate, ammonia, protein, fatty acids, triacylglycerols, amino acids and glycogen), and the enzyme activities of lactate dehydrogenase, malate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were assayed. Fish from treatments P350L49 and P301L81 depicted the best growth. Increase in glycolytic, glycogenolytic and lipolytic activities in liver was observed following dietary lipid increase. In fish fed with high lipid levels, the energetic demand was supplied by enhancement of muscular glycogenesis and lipolysis. The plasma metabolic profile reflected the blood function on metabolites delivery to tissues underlining biochemical adaptations because of changes in the feeding. In conclusion, the increase in dietary lipid plus protein decrease resulted in (i) reduction in fish growth, (ii) augment of liver glycolysis and glycogenolysis (iii) increase in muscular glycogenesis and (iv) predominance of lipolytic metabolism.     

Effect of masking organoleptic properties of fat on diet self‐selection by the sparid Diplodus puntazzo

Fish are able to select a balanced diet according to their nutritional needs by choosing among incomplete feeds or even pure macronutrients. However, the relevance of both the organoleptic properties of diet and the postingestive signals that they produce remains unclear. Thus, sharpsnout seabream were allowed to select between diets containing different edible oils with their organoleptic properties masked by using gelatine capsules. Fish were fed capsules of two different colours so that they could associate the capsule colour with its corresponding postingestive effect. The longitudinal experiment included a first phase during which the fish were adapted to consuming the gelatine capsules. In a second phase, the fish were challenged with two different encapsulated diets: one comprising a complete diet containing fish oil and the other a fat‐free diet. Sharpsnout seabream showed a preference for the fish oil capsules (3.8 ± 1.1 g kg^?1 body weight (BW), 66.8% of total intake) over the fat‐free capsules, showing that they were able to associate the colour of the capsule with their nutritional content through postingestive signals. After that, the fish were challenged to select between the capsules containing the fish oil diet and capsules containing a vegetable oil (linseed or soybean), in which case they showed no preference between diets (2.4 ± 0.3: 2.1 ± 0.5 g kg^?1 BW of fish oil versus linseed oil capsules and 2.2 ± 0.2: 1.8 ± 0.6 g kg^?1 BW of fish oil versus soybean oil capsules), indicating that the fatty acid composition of the different oils was not sufficient to affect dietary selection through postingestive signals. So, in conclusion, when orosensorial information from food is absent, the fish are able to select between diets at a macronutrient level by using postingestive information. However, this information is not sufficient for distinguishing between diets that differ in the type of oil used.