Dose measurement in small animal radiology: how intense is the influence of distance and position of the investigator in relation to the patient?

Radiation exposure of body parts of persons, needed to restrain small animal during the examination, varies depending on the distance and position in relation to the patient, the region investigated, and the exposure settings applied. The aim of the study was to quantify the effects of these factors on the ambient dose. The dosimeter was positioned with varying distance from the direct beam (from 30 to 150 cm) and on different level above the floor (55 cm, 85 cm, and 150 cm. The study consisted of two parts. In the first part a plastic water tank (thickness: 18 cm) was used as source of scatter radiation. Different exposure settings (77 kVp; 20 - 10 - 5 - 2.5 - 1.25 mAs) were applied. In the second part dose was measured during the examination of the abdomen of a large dog (thickness: 18 cm; 77 kVp, 20 mAs) and of the skull of a cat (thickness: 6 cm; 55 kVp, 20 mAs). At the level of the patient (85 cm above the floor) the dose decline relative to the distance followed a quadratic function. In the series "abdomen-dog" the mean dose values ranged from 51.6 microSv (30 cm distance) to 1.02 microSv (150 cm distance). The corresponding doses for the series "skull-cat" were 0.98 microSv and 0.02 microSv, respectively. Comparably lower doses were measured on the lines along the table, when non-irradiated parts of the body were located between the exposed patient volume and the dosimeter. At 150 cm above the floor higher doses were observed relative to the doses at the level of the table. The following conclusions can be drawn: (1.) Depending on the target volume the ambient dose varies in a wide range. (2.) An increase of the distance of only few centimetres is reducing exposure considerably. Therefore persons should make use of it whenever this is possible. (3.) Persons should stand on the short sides of the table while fixing the patient. (4.) Head and neck are relatively highly exposed. Methods to protect the thyroid gland and the eye lens are indicated. (5.) Since different exposure levels can be applied in digital radiography, the range of dose levels is rather wide. Therefore strict dose discipline (e.g. by use of exposure tables and dose indicators) is necessary to avoid continuing overexposure.     

Vermicomposts and/or Arbuscular Mycorrhizal Fungal Inoculation in Relation to Metal Availability and Biochemical Quality of a Soil Contaminated with Heavy Metals

A greenhouse pot experiment was conducted to investigate how the addition of two vermicomposts (commercial or produced from damaged greenhouse tomatoes) and/or inoculation with arbuscular mycorrhizal (AM) fungi affected availability and extractability of P, K and trace metals and biochemical quality of a soil contaminated with heavy metals. The pots were planted with Trifolium repens L., which was harvested 40?days after germination. Shoot and root dry matter of T. repens increased by the addition of both vermicomposts. P, K, Fe, Mn, Cu and Zn uptake by T. repens increased after vermicompost addition, whereas Ni, Pb and Cd concentrations were below the detection limit of the method used. After harvest, AB-DTPA-extractable Fe, Cu, Zn, Cd and Pb decreased in the organically amended soil, whereas AB-DTPA P, K and Mn increased. The addition of both vermicomposts, particularly which made from damaged tomatoes, boosted dehydrogenase, ??-glucosidase and urease activities in the postharvest soil, implying a higher microbial functional diversity and biochemical quality in this amended soil. Although phosphatase activities were greater in the postharvest soils with higher AB-DTPA-extractable metals, the other enzyme activities were negatively affected. The inoculation of the soils with AM fungi had weak effects on plant growth, as well as on the availability and extractability of metals and enzyme activities compared to non-inoculation.     

Effect of Calcium Foliar Application on the Characteristics of Blueberry Fruit during Storage

ABSTRACT

Effect of calcium (Ca) foliar application on blueberry fruit characteristics during storage was investigated. Calcium applications began 28 d after flowering, two levels (3.9 g Ca^{2 +} and 39 g Ca^{2 +}) and a control without calcium were used (0.0; 3.0, and 30 mL L^?1). The fruits were harvested on day 103 and were stored for 56 d at 2 ± 1°C. At harvest time the fruits had a significant statistical different concentration, which were maintained until the last day of storage. The fruit from the 30 mL L^?1 treatment was the highest. The lowest texture levels are found with the treatment without calcium, which shows a statistically significant change from storage day 29. The LMP percentage did not varied in the fruit from the treatment with 30 mL L^?1, but did in the fruit without calcium. Hunter L, b, and the index chromes were influenced by the applied calcium levels, significantly greater at 30 mL L^?1; and by the time of storage in the fruits with treatment of 30 mL L^?1.     

Effect of Foliar Application of Calcium on the Quality of Blueberry Fruits

Effect of foliar application of calcium (0.78 g, 4.68 g, and 7.8 g Ca^{2 +}) in pre-harvest, at three different growing conditions (tunnel, mesh, and ambient), on texture and pectin in blueberries (Vaccinium corymbosum) was studied. Calcium contents in leaves as well in fruits were different (P ≤ 0.05), affected by growing conditions and time. Differences (P ≤ 0.05) in calcium content were found in tunnel cultivar fruit, during the period to cell expansion toward harvest, at calcium foliar level of 5 mL per L (7.8 g). Fruit texture was significantly higher at the beginning of the cell expansion period in the tunnel cultivar fruit, and a linear correlation between calcium concentration and texture was established. Increment in low methoxyl pectin (LMP) was influenced by growing conditions, and was different (P ≤ 0.05) for tunnel cultivar fruit. A good correlation between LMP and calcium content was obtained with the high dose of calcium (5 mL per L).     

Assessing daily egestion rates in earthworms: using fungal spores as a natural soil marker to estimate gut transit time

Earthworms have an important role in ‘bioturbation’—the mixing of soil due to biological processes. Quantification of earthworm bioturbation relies on estimating earthworm egestion rates which in turn depend on two parameters: the gut content of the worms and the gut transit time (GTT). Gut content can be determined relatively easily, but determining GTT is problematic. The present study aimed at estimating daily soil egestion rates of Aporrectodea caliginosa and Lumbricus terrestris, refining the most common approach for estimating GTT by using fungal spores as natural markers in ingested soil. This approach avoids the use of artificial markers that may adversely affect the earthworms. Gut transit time was estimated by tracking the passage of marked soil through the gut by the appearance of the spores in the egested faeces. Gut transit time was estimated to be 9.6?±?0.3 h for A. caliginosa and 11.6?±?0.5 h for L. terrestris. Gut content averaged 465?±?40(± standard error (SE))?mg dw g^?1 dw worm for A. caliginosa and 265?±?80 mg dw g^?1 dw worm for L. terrestris. From these values, daily egestion rates of 1.16 and 0.66 g dw faeces g^?1 dw worm d^?1 were calculated for A. caliginosa and L. terrestris, respectively. Both values compare well to literature values for each species. The presented method for GTT estimation is inexpensive, rapid and easy to evaluate, with spores being a good alternative to existing markers.     

Effects of GH gene polymorphism and sex on carcass traits and fatty acid compositions in Japanese Black cattle

To investigate the effects of bovine growth hormone (bGH) gene polymorphism on carcass traits and fatty acid compositions in Japanese Black cattle caused by nucleotide substitution of CTG (allele A)/GTG (allele B) at codon 127 and of ACG (allele A and B)/ATG (allele C) at codon 172 of bGH, GH genotypes of 135 cattle were determined using allele specific-multiplex polymerase chain reaction (PCR). Allele A gave greater rib thickness and lower melting point of fat (MP) while allele B gave higher C18:1% ( P  < 0.05). Allele C gave higher C18:1, monounsaturated fatty acid (MUFA), unsaturated fatty acid (USFA) percentages ( P  < 0.05). It also gave lower saturated fatty acid (SFA) percentages, higher MUFA/SFA and USFA/SFA ratios, and lower MP ( P  < 0.05). Interactions of sex and GH alleles were analyzed. In heifers, allele A gave higher carcass weight, daily carcass gain, rib eye area, rib thickness, subcutaneous fat thickness, and BMS while allele B gave greater rib eye area and rib thickness ( P  < 0.05). Allele C gave higher C18:1 ( P  < 0.01), MUFA ( P  < 0.01), USFA percentages ( P  < 0.05) and MUFA/SFA and USFA/SFA ratios ( P  < 0.01), and lower C16:0 and SFA percentages ( P  < 0.05) and MP ( P  < 0.01). GH gene polymorphism affected carcass traits and fatty acid compositions although the effects were more pronounced in heifers.     

Quantifying spatiotemporal drivers of environmental heterogeneity in Kruger National Park,South Africa

Context

Environmental heterogeneity is considered an important mechanism of biodiversity. How environmental heterogeneity is characterised by the compositional, structural and functional variation of biotic and abiotic components is a central research theme in conservation.

Objectives

We explore how environmental heterogeneity relates to the underlying physical landscape template and how that relationship changes over space and time. We examine how, in some areas, environmental heterogeneity may also be driven by dynamic ecological processes, and how this relates to patterns of plant species richness.

Method

We use local geographically weighted regression to spatially partition environmental heterogeneity, measured as Landsat spectral variance, into the portion explained by stable physical landscape properties (R²) and the portion unexplained (1?R²) which we term landscape complexity. We explore how this relationship varies spatially and temporally as a function of dynamic ecological processes such as rainfall and season in Kruger National Park, as well as plant species richness at landscape scales.

Results

The significance and direction of relationships varied over space and time and as a function of rainfall and season. R² values generally decreased in higher rainfall summer months and revealed patterns describing the importance of known stable factors relative to unknown dynamic factors. Landscape complexity (1?R²) explained over 70 % of variation in species richness.

Conclusions

Rainfall and seasonality are important drivers of environmental heterogeneity. The spatial arrangement and magnitude of model agreement helped disentangle the relative influence of the physical landscape template on environmental heterogeneity. Given the high correlation with species richness, landscape complexity provides complementary guidance to biodiversity research and monitoring prioritization.

     

Spatial and temporal variations in soil respiration in relation to stand structure and soil parameters in an unmanaged beech forest

Soil CO2 efflux (soil respiration) plays a crucial role in the global carbon cycle and efflux rates may be strongly altered by climate change. We investigated the spatial patterns of soil respiration rates in 144 measurement locations in a 0.5-ha plot and the temporal patterns along a 300-m transect in the 0.5-ha plot. Measurements were made in an unmanaged, highly heterogeneous beech forest during 2000 and 2001. We investigated the effects of soil, roots and forest stand structure on soil respiration, and we also assessed the stability of these spatial patterns over time. Soil temperature alone explained between 68 and 95% of the temporal variation in soil respiration; however, pronounced spatial scatter of respiration rates was not explained by soil temperature. The observed spatial patterns stayed remarkably stable throughout the growing season and over 2 years. The most important structural parameter of the stand was the mean diameter at breast height of trees within a distance of 4 m of the measurement locations (m-dbh4), which explained 10-19% of the variation in soil respiration throughout the growing season. Among the soil chemical parameters, carbon content (bulk as well as dissolved) and magnesium content explained 62% of the spatial variation in soil respiration. The final best model combining soil, root and stand structural parameters (fine root biomass, soil carbon content, m-dbh4 and soil water content) explained 79% of the variation in soil respiration, illustrating the importance of both biotic and abiotic factors.     

Expression of putative expansin genes in phylloxera (Daktulosphaira vitifoliae Fitch) induced root galls of Vitis spp.

Grape phylloxera (Daktulosphaira vitifoliae Fitch) is a serious global pest in viticulture. The insects are sedentary feeders and require a gall to feed and reproduce. The insects induce their feeding site within the meristematic zone of the root tip, where they stay attached, feeding both intra- and intercellularly, and causing damage by reducing plant vigour. Several changes in cell structure and composition, including increased cell division and tissue swelling close to the feeding site, cause an organoid gall called a nodosity to develop. Because alpha expansin genes are involved in cell enlargement and cell wall loosening in many plant tissues it may be anticipated that they are also involved in nodosity formation. To identify expansin genes in Vitis vinifera cv. Pinot noir, we mined for orthologues genes in a comparative analysis. Eleven putative expansin genes were identified and shown to be present in the rootstock Teleki 5C (V. berlandieri Planch. x V. riparia Michx.) using specific PCR followed by DNA sequencing. Expression analysis of young and mature nodosities and uninfested root tips were conducted via quantitative real time PCR (qRT-PCR). Up-regulation was measured for three putative expansin genes (VvEXPA15, -A17 and partly -A20) or down-regulation for three other putative genes (VvEXPA7, -A12, -A20) in nodosities. The present study clearly shows the involvement of putative expansin genes in the phylloxera–root interaction.