Cambial phenology, wood formation and temperature thresholds in two contrasting years at high altitude in southern Italy

Xylogenesis was monitored during 2003 and 2004 in a timberline environment in southern Italy to assess links between temperature, cambial phenology and wood formation on a short-time scale. Wood microcores were collected weekly from May to October from 10 trees of Pinus leucodermis Ant., histological sections were cut with a rotary microtome and anatomical features of the developing and mature tracheids were observed and measured along the growing tree ring. Spring 2003 was hotter than spring 2004, with temperatures up to 2.6 degrees C above historical means. The hotter conditions resulted in an earlier onset of cambial activity and all differentiation phases of about 20 days, resulting in an increased duration of xylogenesis of about 23 days. Air and stem temperatures at which xylogenesis had a 0.5 probability of being active were calculated with logistic regressions fitted on binary responses. In both years, similar thresholds were estimated with daily mean values of 8.2 and 9.5 degrees C for air and stem temperatures, respectively. The observed convergent responses of cambium phenology to temperature during the two contrasting springs confirm the key role of this environmental factor in determining the onset and duration of wood formation in timberline areas. The intra-annual dynamics of ring-width increase differed between years, with significantly narrower rings formed in 2004 than in 2003. These differences were mainly related to cell size because larger earlywood tracheids were produced in 2003. This study demonstrates the plasticity of tree-ring formation in response to high temperatures as a result of modifications in the onset and duration of differentiation.     

Oxygreen process applied on nongerminated and germinated wheat: role of hydroxamic acids

Wheat samples were taken at different stages of germination characterized by their falling number (which is a relevant indicator of germination) from 400 to 60 s. Each batch was treated by the Oxygreen process, a treatment by ozone, in a closed sequential batch reactor. Leucotriene B4 (LTB 4) was induced by germination, but ozone treatment did not increase this effect. Extract obtained from these wheat batches was applied on human epithelial bronchial cells. Wheat extract from nongerminated wheat did not induce any DNA adduct. More the wheat germination gets underway, more DNA adducts are observed. In contrast, germination did not affect the cell viability. Ozonization of wheat exemplified genotoxic effects only if the wheat was germinated. The implication of hydroxamic acids is discussed. In conclusion, ozonization of wheat, of high milling quality, does not pose any problem.     

Phthalate Fate in the Hydrographic Network of the River Seine Basin (France) Under Contrasted Hydrological Conditions

Water, Air, &; Soil Pollution - This study investigated how forest soil acidification is affected by edge proximity. We measured pH(KCl) and exchangeable K, Ca, Mg and Al concentrations of the...     

Influence of diet on growth,reproduction and lipid and fatty acid composition in the sea cucumber Cucumaria frondosa

The suspension‐feeding sea cucumber Cucumaria frondosa is widely distributed in cold waters and is commercially exploited in the North Atlantic. While the species is considered to have potential for aquaculture, its feeding and reproductive biology differs markedly from that of currently cultivated sea cucumbers. Here, for the first time, the influence of food sources on the condition of C. frondosa was experimentally tested. Individuals were fed with either diatoms or fish eggs for 3 months. Specific growth rate (SGR), organ indices, fecundity, gonad maturity and profiles of lipids and fatty acids (FA) in tissues were compared among treatments and with sea cucumbers collected from the field. Individuals fed with fish eggs showed higher SGR and organ indices than all other treatments. The highest proportion of large oocytes was also found in gonad tubules of females from the fish egg treatment, although individuals fed with diatoms were the only ones in which spontaneous spawning occurred. Moreover, gonad and muscle tissues of sea cucumbers from the fish egg treatment presented the highest levels of lipids and essential FA. In contrast, non‐fed sea cucumbers showed negative SGR, relatively low female fecundity and low concentrations of lipids and FA in tissues. While the fish egg diet presented several obvious benefits, phytoplankton remains an important source of carotenoids, which are vital for vitellogenesis in echinoderms. This indicates that mixed diets rich in lipids, essential FA and carotenoids can be further investigated to optimize growth and reproductive output of this species in captivity.     

Early growth and nutrition of hybrid poplars fertilized at planting in the boreal forest of western Quebec

In order to maximize growth and diagnose nutritional requirements of hybrid poplars (Populus spp.) grown in the boreal forest of western Quebec, the Diagnosis and Recommendation Integrated System (DRIS) was evaluated in conjunction with N:P ratios of trees fertilized at planting. Three hybrid poplar clones (747210; P. balsamifera × trichocarpa, 915005; P. balsamifera × maximowiczii, and 915319; P. maximowiczii × balsamifera) were fertilized with 18 combinations of nitrogen (N), phosphorus (P) and potassium (K). Fertilizers used were granules of ammonium nitrate (34.5-0-0) at 3 levels (0, 20 and 40 g tree⁻¹ of N), triple-superphosphate (0-45-0) at 3 levels (0, 25 and 50 g tree⁻¹ of P), and potassium sulfate (0-0-50) at 2 levels (0, 20 g tree⁻¹ of K). After two growing seasons, P fertilization was the most effective in promoting growth and 25 g tree⁻¹ increased mean stem volume by 41% compared to unfertilized trees. The predictive accuracy of the N:P and DRIS diagnosis methods was generally reliable, however they failed to predict some co-limitations of N and P.     

Estimation of distance related probability of animal movements between holdings and implications for disease spread modeling

Between holding contacts are more common over short distances and this may have implications for the dynamics of disease spread through these contacts. A reliable estimation of how contacts depend on distance is therefore important when modeling livestock diseases. In this study, we have developed a method for analyzing distant dependent contacts and applied it to animal movement data from Sweden. The data were analyzed with two competing models. The first model assumes that contacts arise from a purely distance dependent process. The second is a mixture model and assumes that, in addition, some contacts arise independent of distance. Parameters were estimated with a Bayesian Markov Chain Monte Carlo (MCMC) approach and the model probabilities were compared. We also investigated possible between model differences in predicted contact structures, using a collection of network measures.We found that the mixture model was a much better model for the data analyzed. Also, the network measures showed that the models differed considerably in predictions of contact structures, which is expected to be important for disease spread dynamics. We conclude that a model with contacts being both dependent on, and independent of, distance was preferred for modeling the example animal movement contact data.     

Effect of gentamicin on CD3+ T-lymphocyte proliferation for treatment of equine recurrent uveitis: An in vitro study

Objective

The objective of the study was to determine the effect of gentamicin on CD3+ T-lymphocyte proliferation and cell viability using an in vitro cell culture model as a means of investigating the mechanism of action of low-dose intravitreal gentamicin injection.

Animals Studied

Three adult horses with no evidence of ophthalmic or systemic disease.

Procedure

Peripheral blood lymphocytes were treated with gentamicin at concentrations 37.5 μg/mL, 112.5 μg/mL, 187 μg/mL, 375 μg/mL, or 750 μg/mL then stimulated to proliferate with concanavalin A (ConA). 4′,6-diamidino-2-phenylindole (DAPI) and carboxyfluoroscein succinimidyl ester (CSFE) were used as markers of cell viability and cell proliferation, respectively. Following 5-day culture, live cell counts and CSFE fluorescent intensity data were collected via automated cell count and flow cytometry. The experimental design was duplicated using preservative-free gentamicin and a proprietary brand formulation. Statistical analysis was performed using two-way ANOVA with Tukey's multiple comparison test.

Results

No statistically significant comparisons in CD3+ T-lymphocyte live cell counts and geometric mean fluorescent intensity of CSFE were identified between gentamicin concentrations or formulations.

Conclusions

Gentamicin had no effect on equine peripheral blood CD3+ T-lymphocyte cell viability and proliferation in concentrations ranging from “safe” to “retinotoxic” in relation to intravitreal injection volumes. Low-dose intravitreal gentamicin may not suppress the Th1- and Th17-mediated immune response.     

EVALUATION OF STANDARD MAGNETIC RESONANCE CHARACTERISTICS USED TO DIFFERENTIATE NEOPLASTIC,INFLAMMATORY, AND VASCULAR BRAIN LESIONS IN DOGS

Magnetic resonance (MR) imaging characteristics are commonly used to help predict intracranial disease categories in dogs, however, few large studies have objectively evaluated these characteristics. The purpose of this retrospective study was to evaluate MR characteristics that have been used to differentiate neoplastic, inflammatory, and vascular intracranial diseases in a large, multi‐institutional population of dogs. Medical records from three veterinary teaching hospitals were searched over a 6‐year period for dogs that had diagnostic quality brain MR scans and histologically confirmed intracranial disease. Three examiners who were unaware of histologic diagnosis independently evaluated 19 MR lesion characteristics totaling 57 possible responses. A total of 75 dogs with histologically confirmed intracranial disease were included in analyses: 51 with neoplasia, 18 with inflammatory disease, and six with cerebrovascular disease. Only strong contrast enhancement was more common in neoplasia than other disease categories. A multivariable statistical model suggested that extra‐axial origin, T2‐FLAIR mixed intensity, and defined lesion margins were also predictive of neoplasia. Meningeal enhancement, irregular lesion shape, and multifocal location distinguished inflammatory diseases from the other disease categories. No MR characteristics distinguished vascular lesions and these appeared most similar to neoplasia. These results differed from a previous report describing seven MR characteristics that were predictive of neoplasia in dogs and cats. Findings from the current study indicated that the high performance of MR for diagnosing canine intracranial diseases might be due to evaluator recognition of combinations of MR characteristics vs. relying on any one MR characteristic alone.     

Cotton Leaf Senescence can be Delayed by Nitrophenolate Spray Through Enhanced Antioxidant Defence System

Leaf senescence is an oxidative process, and most of the catabolic processes involved in senescence are propagated irreversibly once initiated. An experiment was conducted to test the hypothesis that nitrophenolates (Atonik, a plant growth regulator) spray can delay the leaf senescence through reduced oxidative damage. Atonik 3.75 g a.i. ha^?1 was sprayed during boll filling stage on cotton, and the senescence process was evaluated by quantifying total chlorophyll contents, photosynthetic rate, Fv/Fm ratio, various reactive oxygen species (ROS) content, antioxidant content and antioxidant enzyme activity from 90 days after sowing (DAS) to 130 DAS. The result indicated that nitrophenolate spray reduced the hydrogen peroxide (H₂O₂), superoxide anion (O₂^?) accumulation, lipid peroxidation (malondialdehyde), lipoxygenase activity and membrane permeability over unsprayed control. The antioxidant enzyme activity (superoxide dismutase, SOD; ascorbate peroxidase, APX; peroxidase, POX; glutathione peroxidase, GSH‐Px) were significantly increased by the nitrophenolate spray. POX (118.1 %) and GSH‐Px (143.3 %) activities were enhanced to a higher level compared to APX (8.5 %) activity at 130 DAS. Enhanced accumulation of ascorbate (144.9 %), phenol (154.7 %) and proline (50 %) was seen in nitrophenolate‐sprayed plants compared with unsprayed control plants at 130 DAS. Ascorbate content is increased by higher dehydroascorbate reductase enzyme activity. Ascorbate was thus able to replenish reducing equivalents to phenoxyl radicals resulting in an increase in phenolic compounds. The increased phenolic acid content may be involved in scavenging the ROS produced during senescence process. The higher level of reduced ascorbate and low level of endogenous H₂O₂ in the leaves may be the prerequisite for delayed leaf senescence in the nitrophenolate‐sprayed plants. Based on the present work, it can be concluded that nitrophenolate‐sprayed plants can postpone the leaf senescence by peroxide/phenolic/ascorbate system which is involved in scavenging the ROS produced during leaf senescence.