Comparison of selenomethionine and selenite cycling in freshwater experimental ponds

A comparison of the cycling and fate of ⁷⁵Se in an aquatic ecosystem was investigated when selenite or selenomethionine was introduced as an acute release into two experimental ponds. Biotic and abiotic compartments were periodically sampled to measure ⁷⁵Se concentrations throughout the 318-d experiment. The biotic compartments were periphyton, rooted pondweed (Elodea canadensis), snails (Helisoma sp.), and mosquitofish (Gambusia afflnis). Results show that the uptake rates in the biotic compartments for ⁷⁵Se-selenomethionine were at least an order of magnitude greater than for ⁷⁵Se-selenite. However, elimination rates for respective biotic compartments were similar. Seasonal sediment ⁷⁵Se concentrations in both ponds decreased simultaneously with increases in ⁷⁵Se concentrations within biotic compartments. This suggests that sediment is a secondary source of ⁷⁵Se rather than a sink in some shallow freshwater systems.     

Characterization and extract ability of immobilized 15N from the soil microbial biomass

The microbial biomass of a typical Illinois Mollisol (Flanagan silt loam) was labeled with ¹⁵N, and several extradants were tested to determine their effectiveness in separating the immobilized ¹⁵N from the native soil N. From 3 to 5% of the total N and from 7 to 11% of the tracer N were removed by the milder extradants (i.e. hot water, hot 10mM CaCl₂, hot 5mm NaHCO₃, and cold 10mm NaHCO₃). Acidified permanganate (0.1 m KMnO₄ in 2 m H₂SO₄) and anhydrous formic acid were the most intensive extradants tested; they removed from 10 to 13% of the total N and about 14% of the immobilized ¹⁵N. An inverse relationship was observed between the amount of N extracted and selectivity of the extradants for removing the microbial ¹⁵N, indicating that the milder procedures were more selective in extracting the immobilized ¹⁵N.Distinct differences in the chemical distribution of organic N were observed for the immobilized ¹⁵N and native soil N. Lower proportions of the immobilized ¹⁵N were accounted for as acid-insoluble N and ammonia N (NH₃-N); while higher proportions were found in the amino acid and hydrolyzable unknown (HUN) N fractions.     

Nitrogen forms affect root structure and water uptake in the hybrid poplar

The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a link between form (architecture) and function (water uptake).     

Southern pine beetle regional outbreaks modeled on landscape, climate and infestation history

The southern pine beetle (Dendroctonus frontalis, SPB) is the major insect pest of pine species in the southeastern United States. It attains outbreak population levels sufficient to mass attack host pines across the landscape at scales ranging from a single forest stand to interstate epidemics. This county level analysis selected and examined the best climatic and landscape variables for predicting infestations at regional scales. The analysis showed that, for a given county, the most important factor in predicting outbreaks was that the county was classified as in outbreak status in the previous year. Other important factors included minimum winter temperature and the greatest difference between the average of daily minimums and a subsequent low temperature point, precipitation history either seasonally in the previous year or difference from average over the previous 2 years, the synchronizing effect of seasonal temperatures on beetle populations and the relative percentage of total forest area composed of host species. The statistical models showed that climatic variables are stronger indicators of outbreak likelihood than landscape structure and cover variables. Average climatic conditions were more likely to lead to outbreaks than extreme conditions, supporting the notion of coupling between a native insect and its native host. Still, some extreme events (i.e., periods of very low temperature or very high precipitation) did precede beetle infestation. This analysis suggested that there are predisposing and inciting factors at the large scale but the driving factors leading to individual infestations operate at smaller scales.     

Effect of Kernel Size and Mill Type on Protein,Milling Yield,and Baking Quality of Hard Red Spring Wheat

Optimization of flour yield and quality is important in the milling industry. The objective of this study was to determine the effect of kernel size and mill type on flour yield and end‐use quality. A hard red spring wheat composite sample was segregated, based on kernel size, into large, medium, and small kernels, as well as unsorted kernels. The four fractions were milled in three roller mills: Brabender Quadrumat Jr., Quadrumat Sr., and Bühler MLU‐202 laboratory mills. Large kernels had consistently higher flour yield than small kernels across mills, with the Quadrumat Jr. mill showing the lowest flour yield. Mill type and kernel size significantly affected variation in flour protein molecular weight distribution. When compared with larger kernels, flour milled from the small‐kernel fraction contained a higher gliadin fraction and SDS‐unextractable high‐molecular‐weight polymeric proteins, which had positive correlations with bread loaf volume (r = 0.61, P < 0.05) and mixograph peak time (r = 0.84, P < 0.001). Overall, small kernels could contribute to enhancing flour breadmaking quality while having a detrimental effect on milling yield.     

Nutritional and Quality Traits of Pasta Made from SSIIa Null High‐Amylose Durum Wheat

Food products that are high in fiber and low in glycemic impact are healthier. Amylose is a form of resistant starch that mimics dietary fiber when consumed. A durum wheat (Triticum durum) line was created that lacks starch synthase IIa (SSIIa) activity, a key enzyme in amylopectin biosynthesis, by identifying a null mutation in ssIIa‐B following mutagenesis of a line that has a naturally occurring ssIIa‐A null mutation. Our objective here was to compare seed, milling, pasta, and nutritional characteristics of the SSIIa null line with a wild‐type control line. The SSIIa null line had increased amylose and grain protein with lower individual seed weight and semolina yield. Refined pasta prepared from the SSIIa null semolina absorbed less water, had increased cooking loss, had a shorter cook time, and was considerably firmer even after overcooking compared with the wild‐type line. Color of the SSIIa null cooked and uncooked pasta was diminished in brightness compared with the wild type. Nutritionally, the SSIIa null pasta had increased calories, fiber, fat, resistant starch, ash, and protein compared with the control line, along with reduced total and available carbohydrates. Pasta made from high‐amylose durum wheat provides a significant nutritional benefit along with enhanced end‐product quality via firmer pasta that resists overcooking.     

Meat goat diet supplementation with crude glycerine: Ruminal fermentation metabolism,blood chemistry profile,animal performance and carcass traits

The objective of this experiment was to determine the effects of feeding varying levels of crude glycerine (CG) on dry matter intake (DMI), animal performance, carcass traits and rumen volatile fatty acids (VFA) concentration in meat goats. Twenty-four intact male Boer goats (23.9 ± 1.0 kg initial BW and 4–5 months of age) were randomly assigned to one of four experimental diets (n = 6) containing 30% bermudagrass hay plus 70% concentrate mix with 0, 5, 10 or 15% CG in the diet on an as-fed basis, substituted for the corn portion of the concentrate. Feed offered and refusals were monitored daily for 84 days. Goats were weighed at 28-days interval. Blood and rumen samples were collected on day 84. At the end of the 84-days feeding period, goats were harvested, and carcass characteristics measured. Feed intake, average daily gain (ADG), gain-to-feed ratio (G:F), carcass traits and VFA concentrations were analysed as a completely randomized design. The CG did not influence animal body weight (BW) changes, ADG and G:F ratio but tended to (p = 0.06) decrease DMI. Molar per cent propionic acid increased linearly (p < 0.05) with increasing CG. The acetate: propionate (A:P) ratio decreased (p < 0.05) with increasing amounts of CG in the diet. The CG addition tended to increase (p = 0.09) the longissimus muscle (LM area) in meat goats. In conclusion, CG can replace corn in diet for growing meat goats when fed up to 15% of diet, improving ruminal propionate concentration, but decreasing A:P ratio without affecting animal performance and carcass traits.     

Evaluation of medetomidine-ketamine and dexmedetomidine-ketamine in Chinese water deer (Hydropotes inermis)

ObjectiveTo investigate physiological and sedative/immobilization effects of medetomidine or dexmedetomidine combined with ketamine in free-ranging Chinese water deer (CWD).Study designProspective clinical trial.Animals10 free-ranging adult Chinese water deer (11.0 ± 2.6 kg).MethodsAnimals were darted intramuscularly with 0.08 ± 0.004 mg kg^?1 medetomidine and 3.2 ± 0.2 mg kg^?1 ketamine (MK) or 0.04 ± 0.01 mg kg^?1 dexmedetomidine and 2.9 ± 0.1 mg kg^?1 ketamine (DMK) If the animal was still laterally recumbent after 60 minutes of immobilization, atipamezole was administered intravenously (MK: 0.4 ± 0.02 mg kg^?1, DMK: 0.2 ± 0.03 mg kg^?1). Heart rate (HR) respiratory rate (f_R) and temperature were recorded at 5-minute intervals. Arterial blood was taken 15 and 45 minutes after initial injection. Statistical analysis was performed using Student’s t-test or anova. p < 0.05 was considered significant.ResultsAnimals became recumbent rapidly in both groups. Most had involuntary ear twitches, but there was no response to external stimuli. There were no statistical differences in mean HR (MK: 75 ± 14 beats minute^?1; DMK: 85 ± 21 beats minute^?1), f_R (MK: 51 ± 35 breaths minute^?1; DMK; 36 ± 9 breaths minute^?1), temperature (MK: 38.1 ± 0.7 °C; DMK: 38.4 ± 0.5 °C), blood gas values (MK: PaO₂ 63 ± 6 mmHg, PaCO₂ 49.6 ± 2.6 mmHg, HCO₃^? 30.8 ± 4.5 mmol L^?1; DMK: PaO₂ 77 ± 35 mmHg, PaCO₂ 45.9 ± 11.5 mmHg, HCO₃^? 31.0 ± 4.5 mmol L^?1) and biochemical values between groups but temperature decreased in both groups. All animals needed antagonism of immobilization after 60 minutes. Recovery was quick and uneventful. There were no adverse effects after recovery.Conclusion and clinical relevanceBoth anaesthetic protocols provided satisfactory immobilisation. There was no clear preference for either protocol and both appear suitable for CWD.     

Molecular Detection of Phytophthora ramorum, the Causal Agent of Sudden Oak Death in California, and Two Additional Species Commonly Recovered from Diseased Plant Material

ABSTRACT Sudden oak death is a disease currently devastating forest ecosystems in several coastal areas of California. The pathogen causing this is Phy-tophthora ramorum, although species such as P. nemorosa and P. pseudo-syringae often are recovered from symptomatic plants as well. A molecular marker system was developed based on mitochondrial sequences of the cox I and II genes for detection of Phytophthora spp. in general, and P. ramorum, P. nemorosa, and P. pseudosyringae in particular. The first-round multiplex amplification contained two primer pairs, one for amplification of plant sequences to serve as an internal control to ensure that extracted DNA was of sufficient quality to allow for polymerase chain reaction (PCR) amplification and the other specific for amplification of sequences from Phytophthora spp. The plant primers amplified the desired amplicon size in the 29 plant species tested and did not interfere with amplification by the Phytophthora genus-specific primer pair. Using DNA from purified cultures, the Phytophthora genus-specific primer pair amplified a fragment diagnostic for the genus from all 45 Phytophthora spp. evaluated, although the efficiency of amplification was lower for P. lateralis and P. sojae than for the other species. The genus-specific primer pair did not amplify sequences from the 30 Pythium spp. tested or from 29 plant species, although occasional faint bands were observed for several additional plant species. With the exception of one plant species, the resulting amplicons were smaller than the Phytophthora genus-specific amplicon. The products of the first-round amplification were diluted and amplified with primer pairs nested within the genus-specific amplicon that were specific for either P. ramorum, P. nemorosa, or P. pseudo-syringae. These species-specific primers amplified the target sequence from all isolates of the pathogens under evaluation; for P. ramorum, this included 24 isolates from California, Germany, and the Netherlands. Using purified pathogen DNA, the limit of detection for P. ramorum using this marker system was approximately 2.0 fg of total DNA. However, when this DNA was spiked with DNA from healthy plant tissue extracted with a commercial miniprep procedure, the sensitivity of detection was reduced by 100- to 1,000-fold, depending on the plant species. This marker system was validated with DNA extracted from naturally infected plant samples collected from the field by comparing the sequence of the Phytophthora genus-specific amplicon, morphological identification of cultures recovered from the same lesions and, for P. ramorum, amplification with a previously published rDNA internal transcribed spacer species-specific primer pair. Results were compared and validated with three different brands of thermal cyclers in two different laboratories to provide information about how the described PCR assay performs under different laboratory conditions. The specificity of the Phytophthora genus-specific primers suggests that they will have utility for pathogen detection in other Phytophthora pathosystems.