Spatial activity and expression of plasma membrane H+-ATPase in stem xylem of walnut during dormancy and growth resumption

Plasma membrane H+-ATPase (PM H+-ATPase) plays a key role in nutrient transport, stress responses and growth. To evaluate proton motive force differences between apical and basal parts of acrotonic 1-year-old shoots of walnut (Juglans regia L. cv 'Franquette') trees, spatial and seasonal changes in PM H+-ATPase were studied in mature xylem tissues. During both the dormancy and growth resumption periods, and in both the apical and basal parts of the stem, PM H+-ATPase activity showed positive correlations with the amount of immunodetectable protein. In spring, at the time of growth resumption, higher activities and immunoreactivities of PM H+-ATPase were found in the apical part of the stem than in the basal part of the stem. In spring, the decrease in xylem sugar concentration reflected the high sugar uptake rate. Our data suggest that PM H+-ATPase plays a major role in the uptake of carbohydrates from xylem vessels during growth resumption. These results are discussed in the context of the acrotonic tendency of walnut shoots.     

Comparison of Single and Sequential Extraction Procedures for Assessing Metal Leaching from Dredged Coastal Sediments

Potential uses of dredged sediments have raised questions about leaching of contaminants from such material once transported to other locations and exposed to other environments. In order to estimate leachable, i.e. available fractions of chemical elements in such materials, a number of analytical protocols were proposed, of which none is internationally accepted as a standard procedure. As a consequence, comparability of the results obtained by different protocols in various laboratories is difficult to demonstrate. In the present study some commonly used protocols including a leaching test with (i) seawater, following the modified German Standard Method (DIN), (ii) a single extraction with 25% acetic acid, following the method proposed by the United Nations Environment Programme (UNEP), and (iii) a three-step sequential extraction, following both the original and the modified protocols of the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference – BCR), were performed for assessing the availability of lead, zinc, nickel and copper leachable from dredged marine sediments. A comparison of the results obtained by the different protocols indicated that the single extraction with acetic acid is a reliable simplified technique and allows more rapid evaluations of dredged areas of coastal lagoons in the Northern Adriatic. This procedure provides information on the potentially bioavailable portion of metals.     

Suspended-sediment transport in an intensively cultivated watershed in southeastern California

The purpose of this study is to investigate the variation of sediment movement at multiple spatial and two temporal scales of an agricultural watershed in southeastern California where surface runoff is primarily supplied by irrigation. An extensive turbidity and stage monitoring program based on grab sampling using 500-mL plastic bottles and in situ monitoring using both turbidity sensors and pressure transducers was designed to capture the spatial and temporal heterogeneities of suspended-sediment loads. The obtained turbidity values and stages at weekly and 5-min time scales were subsequently converted to suspended-sediment concentrations and water discharges, respectively, using established calibration methods. Weekly data were analyzed using a mass-balance approach to distinguish erosion and deposition processes in drain channels at various spatial scales. Further analysis on weekly data led to an empirical model describing the process of sediment transport at various spatial scales. The model revealed that drain channels at larger spatial scales (i.e. downstream channels) tended to be dominated by weekly net deposition, while those at smaller spatial scales (i.e. upstream channels) were controlled by weekly net erosion. However, analysis of the 5-min data showed that in small-scale drain channels, large amount of sediment was indeed deposited over a short period of one week (about one day). In the rest of the week, low-intensity erosion prevailed. Therefore, sediment transport in the study watershed was generally controlled by deposition, which supports the necessity of on-going drain-channel dredging by Imperial Irrigation District.     

Effects of grain sampling procedures on fusarium mycotoxin assays in wheat grains

Fusarium mycotoxins are increasingly studied agronomically, chemically, and pathologically in the context of food safety, as a means of preventing new major health crises. Reliable mycotoxin techniques and sampling procedures are required for assessment of the effects of different sources of variation on grain mycotoxin content in agronomic experiments. Analyses were performed with the aim of formulating guidelines for grain sampling to increase the reliability of grain mycotoxin measurement in agronomic experiments. Two toxins in wheat samples, deoxynivalenol and nivalenol, were targeted. With a nested linear mixed model, it was estimated that the uncertainty of nivalenol determination was low (+/-15 microg/kg), whereas that for deoxynivalenol determination was higher (+/-38 microg/kg). It was also found that grinding of the grain decreased the variability of the results. Moreover, despite the heterogeneity in grain mycotoxin content across a given field, it was shown that heads can be harvested manually for agronomic experiments provided that sampling is representative (evenly distributed over the entire plot area). Finally, delaying the assay until after harvest was found to affect the results obtained and should therefore be avoided.     

Modelling the advection and diffusion of eggs and larvae of Greenland halibut (Reinhardtius hippoglossoides) in the north-east Arctic

Since the late 1980s there has been considerable uncertainty in recruitment levels of the north‐east Arctic stock of Greenland halibut (Reinhardtius hippoglossoides). The abundance of several year classes, originally considered very low at 0–3 yr age, appeared higher than expected at the age of 6+. This may be due to poor targeting of recruitment surveys of the younger year classes. The present work considers the transport and dispersion of eggs and larvae of Greenland halibut by numerical modelling in order to predict the locations of the initial recruitment grounds. Current fields from a 3D baroclinic hydrodynamic model are fed into a Lagrangian particle‐tracking model developed for the Barents Sea area. The particles are released into the current at the spawning field along the shelf slope from Lofoten to Bear Island (69–75°N). Vertically, the particles can follow a predefined depth‐by‐age curve or be kept at a fixed depth. This model system is used for different years to examine changes in the drift pattern. The results indicate that spawning location, transport depth and inflowing activity to the Barents Sea are important factors influencing the distribution of juveniles.     

Generational growth rate estimates of <Emphasis Type="Italic">Diabrotica virgifera virgifera</Emphasis> populations (Coleoptera: Chrysomelidae)

Modelling population dynamics of the maize pest Diabrotica virgifera virgifera LeConte (western corn rootworm; Coleoptera: Chrysomelidae) requires knowledge on the growth rate (=net reproductive rate) of the species. We investigated the generational (=annual) growth rate of D. v. virgifera in isolated maize fields in southern Hungary and eastern Croatia over several years. The population densities of D. v. virgifera were assessed by absolute counts of emerging adults in 90 gauze cages per study field. Emergence ranged from 1.3 to 30.7 adults per m² in continuous maize field sections, and from 0.3 to 5.1 adults per m² in adjacent first-year maize sections. The annual growth rates of D. v. virgifera ranged from 0.5 to 13, and averaged in close to 4. These experimentally assessed growth rates could complement growth estimates in population dynamic models, particularly those for forecasting the population growth to economic thresholds or for estimating population build-ups after new introductions of this alien species in Europe. As an example, the determined growth rate was used to estimate that the first documented successful introduction of this species into Europe occurred between 1979 and 1984, which is 8–13 years before the detection of this species and its larval damage in maize fields near Belgrade, Serbia, in 1992.     

Diagnosis and surgical management of a fractured atlas in a cat

A 6-month-old male-castrated domestic shorthair cat was presented shortly after being bitten on the neck by a large breed dog. On presentation the cat was non-ambulatory tetraparetic with preserved deep pain perception. Plain radiographs of the neck did not show any abnormalities. Computed tomography was performed and showed a right-sided depressed fracture of the dorsal lamina of the atlas. A partial dorsal laminectomy was performed to alleviate the spinal cord compression. The cat made a full recovery within 12 weeks of surgery.     

Direct and Residual Effect of Sulphur Fertilization on Yield,Uptake and Use Efficiency in Indian Mustard and Succeeding Rice Crop

A field experiment was conducted on Indian mustard (Brassica juncea) with five levels of sulfur (S), 0, 15, 30, 45, and 60 kg S ha^?1 in sub-tropical Inceptisol of Jammu, North India. The residual effect of S on rice crop was evaluated. The seed and stover yield of mustard increased in the linear order up to 60 kg S ha^?1 but significant yield increase was obtained up to 30 S kg ha^?1 which was 21.4 percent higher in comparison to the yield obtained in control. The uptake of S at maturity was significantly affected with all the levels of S application. The seed S uptake increased significantly up to 30 kg S ha^?1 and stover 45 kg S ha^?1. The residual effect of S was convincing in enhancing the rice yield to the tune of 5.3% over control, but was statistically non-significant. The S uptake was also favourably influenced by the residual S which was evidenced through increased S use efficiency. Agronomic and physiological efficiency as well as S recovery were all greatly influenced by direct and residual effect of S. Apparent S recovery was higher at 30 kg S ha^?1 in mustard (12.06%).     

Effects of syringe material and temperature and duration of storage on the stability of equine arterial blood gas variables

OBJECTIVES: To evaluate the consistency of partial pressures (P) of arterial oxygen (aO(2)), arterial carbon dioxide (aCO(2)) and pH measurements in equine carotid arterial blood samples taken into syringes made from three different materials and stored at room temperature or placed in iced water for measurement at three different times. STUDY DESIGN: Prospective observational study over 19 days. ANIMALS: Four clinically normal Thoroughbred or Thoroughbred-cross horses (three geldings, one mare, mean age 6.25 years, range 5-7 years). METHODS: Identical blood samples were taken on two separate occasions from the carotid arteries of the four horses into syringes made of glass, plastic and polypropylene. PaO(2), PaCO(2) and pH determinations were performed on blood from each syringe type at 10, 60 and 120 minutes post-sampling with samples stored at room temperature (approximately 20 degrees C) or in iced water (approximately 0 degrees C). Data were analysed by anova and a split plot model fitting syringe within horse X pair and time within temperature within syringe. RESULTS: Syringe material, storage temperature and time before analysis all had significant effects on PaO(2) (p < 0.001). PaCO(2) was unaffected by syringe material or storage temperature. However, over 120 minutes, storage duration significantly (p = 0.002) affected values. Temperature of storage and duration prior to analysis both significantly affected pH values (p = 0.005 and p < 0.001, respectively), but syringe material did not. Several significant interactions between these variables were noted. CONCLUSIONS: Equine arterial blood gas determination has a different sensitivity to storage conditions compared to other veterinary species. CLINICAL RELEVANCE: For accurate equine arterial blood analysis, PaO(2) samples need to be analysed within 10 minutes or taken into glass syringes, stored on ice and analysed at 2 hours post-sampling. PaCO(2) and pH measurements can be performed on samples stored in glass, plastic or polypropylene syringes at room temperature for up to 1 hour post-sampling.