A new method for evaluating symplastic cadmium absorption in the roots of Solanum melongena using enriched isotopes 113Cd and 114Cd

Radioisotope techniques are well known as methods for evaluating symplastic ion absorption in roots. In the present study, a new method for evaluating symplastic cadmium (Cd) absorption in plant roots was developed using the enriched isotopes ¹¹³Cd and ¹¹⁴Cd. Seedlings of Solanum melongena were exposed to an enriched isotope solution of ¹¹³Cd at 25°C for 30 min. The roots were excised from each seedling and were then immersed in a cold buffer solution without Cd at 2°C for 120 min to suppress the metabolic activity of the roots. Finally, the roots were treated with a cold buffer solution containing enriched stable isotope ¹¹⁴Cd at 2°C for 120 min, whereby the apoplastically bound ¹¹³Cd was desorbed. We tested the validity of our method for evaluating symplastic Cd in roots compared with the conventional method based on differences in the amount of Cd absorbed at 2°C and 25°C using unlabeled Cd. There was no difference in the symplastic Cd content of the roots between the two methods. These results indicate that it is possible to evaluate the symplastic Cd content in roots using the enriched isotopes ¹¹³Cd and ¹¹⁴Cd.     

Effect of soil air volume change on CH4 consumption in brown forest soil

The relationship between soil air volume and CH₄ consumption in brown forest soils was investigated. The CH₄ consumption was negatively affected when the soil air volume decreased in experiments carried out bothin situ and in the laboratory. A strong dependence of the CH₄ consumption on the soil air volume was found in the laboratory experiment. These results indicate the possibility that the soil air volume is the primary rate-limiting factor for the CH₄ consumption in forest soil. Thus our work suggests that the other factors by which CH₄ consumption might be affected should be examined under the same air volume condition in the soil. To obtain accurate data, we need to be careful not to change the air volume by trampling or disturbing during the measurement of the natural methane fluxin situ.     

The pharmacological effects of the anesthetic alfaxalone after intramuscular administration to dogs

The pharmacological effects of the anesthetic alfaxalone were evaluated after intramuscular (IM) administration to 6 healthy beagle dogs. The dogs received three IM doses each of alfaxalone at increasing dose rates of 5 mg/kg (IM5), 7.5 mg/kg (IM7.5) and 10 mg/kg (IM10) every other day. Anesthetic effect was subjectively evaluated by using an ordinal scoring system to determine the degree of neuro-depression and the quality of anesthetic induction and recovery from anesthesia. Cardiorespiratory variables were measured using noninvasive methods. Alfaxalone administered IM produced dose-dependent neuro-depression and lateral recumbency (i.e., 36 ± 28 min, 87 ± 26 min and 115 ± 29 min after the IM5, IM7.5 and IM10 treatments, respectively). The endotracheal tube was tolerated in all dogs for 46 ± 20 and 58 ± 21 min after the IM7.5 and IM10 treatments, respectively. It was not possible to place endotracheal tubes in 5 of the 6 dogs after the IM5 treatment. Most cardiorespiratory variables remained within clinically acceptable ranges, but hypoxemia was observed by pulse oximetry for 5 to 10 min in 2 dogs receiving the IM10 treatment. Dose-dependent decreases in rectal temperature, respiratory rate and arterial blood pressure also occurred. The quality of recovery was considered satisfactory in all dogs receiving each treatment; all the dog exhibited transient muscular tremors and staggering gait. In conclusion, IM alfaxalone produced a dose-dependent anesthetic effect with relatively mild cardiorespiratory depression in dogs. However, hypoxemia may occur at higher IM doses of alfaxalone.     

Central venous blood gas and acid-base status in conscious dogs and cats

To determine the reference level of central venous oxygen saturation (ScvO₂) and clinical efficacy of central venous blood gas analysis, partial pressures of oxygen and carbon dioxide, pH, oxygen saturation, base excess (B.E.) and HCO₃ concentration were compared between simultaneously obtained central venous and arterial blood samples from conscious healthy 6 dogs and 5 cats. Comparisons between arteriovenous samples were performed by a paired t-test and Bland-Altman analysis. Between arteriovenous samples, B.E. showed good agreement, but there were significant differences in other parameters in the dogs, and no good agreement was detected in cats. The ScvO₂ in dogs and cats were 82.3 ± 3.5 and 62.4 ± 13.5%, respectively. Central venous blood gas analysis is indispensable, especially in cats.     

Synthesis of haptens for development of antibodies to alkylphenols and evaluation and optimization of a selected antibody for ELISA development

The development of an enzyme-linked immunosorbent assay (ELISA) based on polyclonal antibodies for a class of endocrine disrupting compounds, 4-nonylphenol, is described. The parent molecule was derivatized at the ortho position of the free phenolic hydroxyl group to obtain the hapten, NP1, and it was conjugated with keyhole limpet hemocyanin, which was used as an immunogen. Four antisera were generated and screened against three coating antigens. The most sensitive ELISA from the screening tests (antiserum NP03As, 1/1000, and coating antigen NP1-BSA, 1 microg/mL) was further optimized and characterized. The influence of various physicochemical factors (organic solvent, pH, ion strength) was investigated. Methanol as the additive organic solvent was found to be the best organic solvent for the ELISA, with optimal sensitivity observed at a concentration of 5%. The ELISA parameters were changed at more acidic or basic pH values, whereas higher ionic strengths strongly suppressed the I(50) value and the maximum absorbance. The most sensitive ELISA for 4-nonylphenol exhibited an I(50) value of 38.6 +/- 5.5 microg/L, with a dynamic range from 12 to 350 microg/L, and the lower limit of detection was 7.7 +/- 1.3 microg/L. The optimized ELISA displayed no significant cross-reaction against the parent compounds, nonylphenol ethoxylates, degradation products, carboxylates, and bisphenol A, except in 4-octylphenol.     

Evaluation and validation of a commercially available enzyme-linked immunosorbent assay for the neonicotinoid insecticide imidacloprid in agricultural samples

The performance of a commercially available microtiter plate ELISA kit for the determination of the neonicotinoid insecticide imidacloprid was evaluated for sensitivity, selectivity, influence of organic solvent used for extraction procedure, matrix interference originated from agricultural sample, accuracy, and method comparison with conventional HPLC analysis. The limit of detection for the kit (0.1 or 0.5 ng/mL) was determined. The working range (1-39 ng/mL) experimentally calculated on the basis of a criterion, which is determined as the range from I(20) to I(80), was comparable to that established by the manufacturer (1-50 ng/mL). The linearity of the standard curve based on the kit-assembled standard solutions agreed with the one based on the self-made standard solutions. Specificity studies indicate that the imidacloprid monoclonal antibody can readily distinguish the target compound from other structurally related neonicotinoid analogues and some metabolites, with the exception of clothianidin, the cross-reactivity of which was approximately 12%. To extract imidacloprid from an agricultural sample (apple) as simply and rapidly as possible, some extraction methods were examined. Consequently, the extraction method with hand-shaking for 5 min was the best among the examined methods. For the analysis of imidacloprid in apple samples, it was extracted directly with methanol and the extracts were diluted 10-fold (100-fold in the well) with water prior to ELISA analysis. No significant matrix interference was observed with the dilution factor. Recoveries of imidacloprid from fortified apple samples ranged from 87.7 to 112.0%. The results obtained with the ELISA kit correlated well with those by the reference method (conventional HPLC analysis) for apple samples (r > 0.998). These findings strongly indicate that the ELISA kit may be employed routinely for an on-site imidacloprid residue analysis of apple samples.     

Methane emissions from stems of Fraxinus mandshurica var. japonica trees in a floodplain forest

We measured methane (CH₄) emissions from the stem surfaces of mature Fraxinus mandshurica var. japonica trees in a floodplain forest. Flux measurements were conducted almost monthly from May to October 2005, and positive CH₄ fluxes were detected throughout the study period, including the leafless season. The mean CH₄ flux was 176 and 97 μg CH₄ m⁻² h⁻¹ at the lower (15 cm above the ground) and upper (70 cm above the ground) stem positions, respectively. The CH₄ concentration was lower in soil gas than in ambient air to a depth of at least 40 cm. One possible source of CH₄ emitted from the stems might be the dissolved CH₄ in groundwater; maximum concentrations were 10,000 times higher than atmospheric CH₄ concentrations. Our results suggest that CH₄ transport from the submerged soil layer to the atmosphere may occur through internal air spaces in tree bodies.     

Chemical Characteristics and Acid Buffering Capacity of Surface Soils in Japanese Forests

To determine the geological distribution of acid buffering capacity and exchangeable Al of forest soils in Japan, surface soils under forest vegetation were collected nationwide from a total of 1,034 sites. Generally, surface soils in Japanese forests are mostly acidic and low in both exchangeable cation content and exchangeable Al. The median of soil pH(H₂O), total exchangeable cations, and exchangeable Al are 5.1, 76 mmol₍₊₎Kg^?1, and 19.6 mmol₍₊₎kg^?1, respectively. Acid buffering capacities of selected soils were determined using a soil column, which was comparable to the capacity that resulted from cation exchanges with protons. Soils with high buffering capacity and low exchangeable Al are widely distributed in Japan, and overlap with the areas of Andisol distribution. Volcanogenic materials seem to mask soil characteristics derived from underlying geology even though they are not Andisols. However, central to western Honshu Island, Shikoku Island, and northern Kyushu Island showed weak acid buffering capacities with high exchangeable Al potential in surface soils.     

Effects of intravenous diazepam or microdose medetomidine on propofol-induced sedation in dogs

This crossover study tested the hypothesis that both diazepam and microdose medetomidine would comparably reduce the amount of propofol required to induce sedation. Four different medications, namely high-dose diazepam (0.4 mg/kg intravenously [IV]), low-dose diazepam (0.2 mg/kg IV), medetomidine (1 mug/kg IV), and placebo (0.5 mL physiological saline IV) were followed by propofol (8 mg/kg IV) titrated to a point where intubation could be performed. The effects of medetomidine were comparable to the effects of high-dose diazepam and significantly better than the effects of low-dose diazepam or placebo. Dogs in all treatment groups had transient hypoxemia, and induction and recovery qualities were similar.