Pesticide discharge and water management in a paddy catchment in Japan

Concentrations of several pesticides were monitored in a paddy block and in the Kose river, which drains a paddy catchment in Fukuoka prefecture, Japan. Detailed water management in the block was also monitored to evaluate its effect on the pesticide contamination. The concentrations of applied pesticides in both block irrigation channel and drainage canal increased to tens of μg/L shortly after their applications. The increase in pesticide concentrations was well correlated with the open of irrigation and drainage gates in the pesticide-applied paddy plots only 1–3 days after pesticide application. High concentration of other pesticides, mainly herbicides, was also observed in the inflow irrigation and drainage waters, confirming the popularity of early irrigation and drainage after pesticide application in the area. The requirement of holding water after pesticide application (as a best management practice) issued by the authority was thus not properly followed. In a larger scale of the paddy catchment, the concentration of pesticides also increased significantly to several μg/L in the water of the Kose river shortly after the start of the pesticide application period either in downstream or mid–upstream areas, confirming the effect of current water management to the water quality. More extension and enforcement on water management should be done in order to control pesticide pollution from rice cultivation in Japan.     

Numerical modeling of environmental behavior and fate of tributyltin in a semi-closed bay

The environmental behavior and fate of tributyltin (TBT) in the northern Ariake Sea, resulting from the use of TBT-containing antifouling paints on hulls of ships, pleasure crafts and docking facilities, was assessed by numerical simulations. First, a mathematical model was devised on the basis of a non-steady state equilibrium, one box multi-compartment model consisting of the surface micro-layer, the water column, the mud-layer, and the bottom sediment compartments. The movement of TBT among the four compartments was modeled by resuspension of bottom mud, deposition of suspended sediment, film penetration and water advection in each compartment. Furthermore, a one-dimensional diffusion equation was introduced into the bottom sediment compartment to calculate profile distribution of TBT. The reactivity of TBT considered within the compartments included biological degradation, adsorption to particulate matter and diffusion. Next, the optimal amount of past TBT loads, reflecting the recent observations of TBT concentration in the waters and sediments of the northern Ariake Sea, was searched by a simple genetic algorithm. The relative sensitivity of various model parameters were also determined to identify the more important parameters for estimating the environmental behavior and fate of TBT. Finally, the future status of TBT contamination of the northern Ariake Sea was predicted assuming the discontinued use of TBT-containing antifouling paints. Despite its simple model structure relative to hydraulics, it was concluded that this multi-compartment model adequately estimated the environmental behavior and fate of TBT.     

Comparison of three dielectric moisture sensors for measurement of water in saline sandy soil

The number of sensor types available for measuring soil water content has increased but investigations to compare their performance in saline soils needs clarification. In this study the performance of commercially available, low-cost soil moisture sensors [time domain reflectometry (TDR), PR1 and WET], all measuring changes in the dielectric constant of the soil water, was evaluated under laboratory conditions in a saline sandy soil. The three sensors were also tested in the same sandy soil growing drip irrigated sorghum ( Sorghum bicolor L. cv. Moench) in a greenhouse. Plants were irrigated daily with either saline water (ECw: 9.4 dS/m) or fresh water (0.11 dS/m). The volume of irrigation was equivalent to 100% of the pan evaporation. The results showed that measurement accuracy was strongly dependent on the salinity of the soil. The PR1 sensor overestimated volumetric water content ( θ ) when the salinity level exceeded 4 dS/m [root mean square of the standard error (RMSE) = 0.009 cm³/cm³]. The WET sensor significantly overestimated θ irrespective of the salinity level (RMSE = 0.014 cm³/cm³). The TDR sensor estimated θ with more accuracy (RMSE = 0.007   cm³/cm³) and thus can be considered as more reliable than the other two sensors. The calibrations were strongly affected by the salinity level of the water, so we recommend that calibration equations are modified to take account of salinity.     

A model for the relationship between form-factors for stem volume and those for stem surface area in coniferous species

A model that describes the relationship between the form-factors for stem volume and those for stem surface area in coniferous species is proposed. The model is derived assuming that the stem form of a tree can be expressed by Kunze's equation. The model indicated that the form-factor for stem surface area was directly proportional to the square root of the form-factor for stem surface volume, independent of the stem position. The proposed model expressed the relationship of the form-factors for Japanese cedar (Cryptomeria japonica D. Don) and Japanese cypress (Chamaecyparis obtusa Endl.) trees well. Therefore, the form-factors for stem surface area could be estimated from those for stem volume. No significant difference in the coefficient was found between Japanese cedar and Japanese cypress trees, indicating that the proportional coefficient would be common between the two species. Many studies have shown that the form-factors for stem volume at 0.7 and 0.5 in relative height were, respectively, almost steady at 0.7 and 1.0, independent of species, district, density control, and growth stage. Substituting these universal values into the proposed model, the form-factors for stem surface area at 0.7 and 0.5 in relative height were estimated to be 0.730 and 0.873, respectively. The estimated values of the form-factors for stem surface area would be universal for coniferous species. The proposed model also showed that the breast height form-factor for stem surface area decreased sharply with the increase in total tree height, when the height was less than 10 m. However, after the tree attained the total height of 10 m, the breast height form-factor gradually decreased with the total tree height approaching its asymptotic value of 0.605. In conclusion, the model proposed here can be used to describe the relationship between form-factors for stem volume and those for stem surface area successfully.     

Immunohistochemical evaluation of canine ovarian tumors

Canine ovarian tumors (epithelial tumor, sex-cord stromal tumor, germ cell tumor) classifying into 9 histological types were examined immunohistochemically using placental alkaline phosphatase (PLAP), cytokeratin7 (CK7), desmin, S100, AE1/AE3, inhibin alpha, vimentin, and alfa feto-protein (AFP). The papillary and tubular types observed in epithelial tumors were immunoreactive for desmin and AE1/AE3. The papillary type was also immunoreactive for PLAP and CK7. The solid type, nest type, cord type, palisade type, cystic type and spindle type, which were observed in sex-cord stromal tumors, showed a positive immunoreaction for S100 but little or no positive immunoreaction for inhibin alpha with an exception of positive result in the palisade type. Most of the sex-cord stromal tumors were AE1/AE3-positive except for the palisade type. In the cobblestone type observed in germ cell tumors, only vimentin and AFP were positive. The present study elucidated the detailed histological and immunohistochemical characteristics of canine ovarian tumors.     

Malignant transformation of T-cell large granular lymphocyte leukemia in a dog

An 8-year-old spayed female Golden Retriever was referred to us for evaluation of mild lymphocytosis. The peripheral lymphocytes were comprised of mostly large granular lymphocytes (LGLs), and flow cytometry showed that they were mostly CD3+8+ T lymphocytes. Clonal rearrangement of the T-cell receptor gene was identified in the peripheral blood, and the dog was therefore diagnosed with LGL chronic leukemia. The dog was subclinical without treatment until hospitalization on day 154, at which point the lymphocytes looked like lymphoblasts and the surface markers changed to CD3-8-. This was regarded as malignant transformation from LGL chronic leukemia to the acute type. Sequential chemotherapy was started, but the dog died on day 190. Necropsy revealed tumor cell infiltration into the heart, skin, and brain.     

The perivitelline space-forming capacity of mouse oocytes is associated with meiotic competence

Although mouse oocytes progressively acquire meiotic competence during their growth in the ovaries, only half of full-grown oocytes can accomplish meiosis. Two types of full-grown oocytes have been reported on the basis of their chromatin configuration, the surrounded-nucleolus (SN) type and the non-surrounded-nucleolus (NSN) type. Therefore, full-grown oocytes collected from the ovaries of adult animals comprise a heterogeneous population; some oocytes are meiotically incompetent (NSN-type), and some are competent (SN-type). In the present study, we found that full-grown oocytes could be classified into two groups using the criterion of formation of the perivitelline space (PVS) after culture with 3-isobutyl-1-methylxanthine (IBMX) for 1 h. In oocytes with a PVS, actin-filled processes within zona pellucidae originating from cumulus cells were reduced, while they were rich in oocytes without a PVS, suggesting that a reduction in these processes contributes to PVS formation. PVS formation was highly correlated with meiotic competence and SN-type configuration. The results of this study demonstrate that PVS formation is a useful criterion for easily distinguishing between SN- and NSN-type oocytes, without injury to the cells.     

Immunohistochemical evaluation of canine ovarian cysts

To clarify the immunohistochemical characteristics of canine ovarian cysts, 109 canine ovarian cysts (57 cysts of subsurface epithelial structures: SES, 26 graafian follicle cysts, 12 cystic rete ovarii and 14 cysts difficult to classify morphologically) were examined regarding their lining cells immunohistochemically using antibodies against placental alkaline phosphatase (PLAP), S100, inhibin alpha, desmin and AE1/AE3. Both cysts of SES and cystic rete ovarii had a positive immunoreaction to desmin and AE1/AE3, whereas all cysts all but graafian follicle cysts were negative for inhibin alpha. PLAP-positive immunoreaction was observed only in cysts of SES. Graafian follicle cysts had a positive immunoreaction to inhibin alpha, but were negative for PLAP, desmin and AE1/AE3. Fourteen cysts were difficult to classify morphologically because these cysts had single-squamous lining cells and lacked other morphological characteristics. However, these unclassified cysts were immunohistochemically divided into two groups, including positive and negative cysts, by the reactivity of PLAP. The PLAP-positive cysts were considered large cysts of SES. These results suggest that PLAP was a useful marker for classification of cysts of SES, although cysts originating from SES are not always positive for this antigen.     

Efficiency of PCR-RF-SSCP marker production in Brassica oleracea using Brassica EST sequences

Efficiencies of SCAR, CAPS and PCR-RF-SSCP marker production were investigated using two combinations of breeding lines in Brassica oleracea. Published EST sequences of B. oleracea, Brassica rapa, Brassica napus, and Arabidopsis thaliana and newly determined nucleotide sequences of anther cDNA clones from B. oleracea were used for designing primer pairs to amplify genes. The percentage of primer pairs yielding DNA amplification of a single gene was higher in primer pairs of B. oleracea (91%) than those of B. rapa (56%) and A. thaliana (17%). Single DNA fragments amplified by 9% of the primer pairs showed polymorphism as SCAR markers between a broccoli line and a Chinese kale line by agarose-gel electrophoresis. CAPS analysis showed different band patterns in 32% of the same-sized DNA fragments, and PCR-RF-SSCP analysis revealed DNA polymorphism in 52% of those showing no DNA polymorphism by CAPS. In total, 71% of the single DNA fragments were converted to DNA markers. The frequency of DNA polymorphism between parental lines of a cabbage F₁ hybrid was lower, 5% by SCAR and 12% by CAPS. However PCR-RF-SSCP analysis revealed DNA polymorphism in 21% of the DNA fragments showing no polymorphism by CAPS. These results suggest that PCR-RF-SSCP analysis enables highly efficient DNA marker production for mapping of genes in Brassica using progeny, even progeny of closely related parents. Analysis of selfed seeds of broccoli F₁ cultivars using PCR-RF-SSCP markers indicated that PCR-RF-SSCP analysis is also applicable to seed purity tests.     

Temporal and spatial dynamics of begomovirus disease in tomatoes in central Brazil

Over the last two decades, begomovirus diseases have increased in importance in Brazilian tomato crops. The major management strategy in Brazil is the application of insecticides to control the whitefly vector, but this is often unsuccessful. The objective of this work was to study the spatial and temporal progression of the disease in two processing tomato production areas in Central Brazil. A total of 24 plots (225 plants each) in six fields were evaluated weekly by visual inspection for plants with begomovirus symptoms. The predominant begomovirus in tomato plants with symptoms was Tomato severe rugose virus, and it was also detected in weeds and other crop plants. No correlation between incidence of begomovirus disease and whitefly population was found. The disease progression was rapid, with a slightly aggregated distribution of plants with symptoms. No relevant differences were observed in the temporal and spatial analyses, although an important difference was detected between plots located at the centre (PC) and the edge (PE) of the fields. In the temporal analysis, the begomovirus incidence and area under disease progress curve values were lower in PC than in PE. In the spatial analysis, plants with begomovirus symptoms were more aggregated in PC than in PE. These results suggest that the distribution of plants with symptoms in PC and PE could be a result of three dissemination mechanisms: one random (primary) and two aggregated, a real secondary spread, and a false secondary spread. The implications of these differences on disease management are discussed.