Output of methylmercury from a Catchment in northern Sweden

The runoff output of methylmercury (MeHg) from the 50 ha Svartberget Catchment in northern Sweden was studied during 1993. These outputs are compared to those from the Gårdsjön Catchment in the southwestern part of Sweden. Although the wet deposition of MeHg is several times higher in southern Sweden the output of MeHg per unit area from the two catchments was comparable (0.12 g /km_* ²yr). Furthermore, the concentration of MeHg (0.4 ng/L) in the Svartberget Catchment was more than twice that from the Gårdsjön Catchment. These results suggest that the contemporary wet deposition of MeHg in itself is not a good indicator of runoff concentration or output per unit area. DOC transport and catchment characteristics such as wetland area, or possibly other forms of contemporary atmospheric deposition may all be more important for explaining MeHg output from the terrestrial ecosystem.     

Metabolism of flupyrazofos in the isolated perfused rat liver

To investigate the hepatic metabolism of the new insecticide flupyrazofos [O,O-diethyl O-(1-phenyl-3-trifluoromethylpyrazol-5-yl) phosphorothioate], isolated rat liver was perfused with flupyrazofos under single-pass conditions. In outflow perfusate and bile, 1-phenyl-3-trifluoromethyl-5-hydroxyprazole (PTMHP), PTMHP-sulfate and PTMHP-glucuronide conjugates were identified as the metabolites of flupyrazofos. However, O,O-diethyl O-(1-phenyl-3-trifluoromethylpyrazol-5-yl) phosphate (flupyrazofos oxon) was not detected. A HPLC method with UV detection was used to investigate the hepatic disposition of flupyrazofos and its metabolite PTMHP. The concentrations of flupyrazofos, PTMHP and PTMHP conjugates in outflow perfusate reached steady-state levels within 20 min after commencing perfusion of 7.3 microM flupyrazofos. At steady state, the mean extraction ratio of flupyrazofos was 0.93 (+/- 0.01) and clearance was 26.1 (+/- 0.2) ml min-1 which nearly approached perfusate flow rate (28 ml min-1). PTMHP accounted for 55.7 (+/- 5.8)% of eliminated flupyrazofos and was recovered as unchanged PTMHP, PTMHP-sulfate and PTMHP-glucuronide in the bile as well as the outflow perfusate.     

Effect of catheter size and injection rate of contrast agent on enhancement and image quality for triple‐phase helical computed tomography of the liver in small dogs

Rapid contrast injection is recommended for triple‐phase helical computed tomography (CT) of the liver. However, a large‐gauge catheter is needed for faster contrast injection and this is not practical for small breed dogs or cats. The purpose of this crossover group study was to evaluate applicability of a lower injection rate with a small‐gauge (G) catheter for triple‐phase hepatic CT in small dogs. Triple‐phase CT images were acquired for six beagle dogs using three protocols: an injection rate of 1.5 ml/s with a 24 G catheter, 3.0 ml/s with a 22 G catheter, and 4.5 ml/s with a 20 G catheter. Enhancement of the aorta, portal vein, and hepatic parenchyma was measured in each phase (arterial, portal, and delayed) and image quality was scored subjectively by two observers. Injection duration, time to scan delay, and time to peak enhancement were also recorded. Contrast injection duration decreased with a higher injection rate (n = 6, P ≤ 0.01), but time to peak enhancement and time to scan delay were not significantly affected by injection rates and catheter sizes. Contrast injection rate did not significantly affect aortic, portal, and hepatic enhancement. In addition, separation between each phase and quality of images was subjectively scored as good regardless of injection rate. Findings from the current study supported using an injection rate of 1.5 ml/s with a catheter size of 24 G for triple‐phase hepatic CT in small dogs (weight < 12 kg).     

Effect of heat treatment on the antioxidant activity of extracts from citrus peels

The effect of heat treatment on the antioxidant activity of extracts from Citrus unshiu peels was evaluated. Citrus peels (CP) (5 g) were placed in Pyrex Petri dishes (8.0 cm diameter) and heat-treated at 50, 100, or 150 degrees C for 10, 20, 30, 40, 50, and 60 min in an electric muffle furnace. After heat treatment, 70% ethanol extract (EE) and water extract (WE) (0.1 g/10 mL) of CP were prepared, and total phenol contents (TPC), radical scavenging activity (RSA), and reducing power of the extracts were determined. The antioxidant activities of CP extracts increased as heating temperature increased. For example, heat treatment of CP at 150 degrees C for 60 min increased the TPC, RSA, and reducing power of EE from 71.8 to 171.0 microM, from 29.64 to 64.25%, and from 0.45 to 0.82, respectively, compared to non-heat-treated control. In the case of WE from CP heat-treated at the same conditions (150 degrees C for 60 min), the TPC, RSA, and reducing power also increased from 84.4 to 204.9 microM, from 15.81 to 58.26%, and from 0.27 to 0.96, respectively. Several low molecular weight phenolic compounds such as 2,3-diacetyl-1-phenylnaphthalene, ferulic acid, p-hydroxybenzaldoxime, 5-hydroxyvaleric acid, 2,3-diacetyl-1-phenylnaphthalene, and vanillic acid were newly formed in the CP heated at 150 degrees C for 30 min. These results indicated that the antioxidant activity of CP extracts was significantly affected by heating temperature and duration of treatment on CP and that the heating process can be used as a tool for increasing the antioxidant activity of CP.     

Sesame oleosin and prepro-2S albumin expressed as a fusion polypeptide in transgenic rice were split, processed and separately assembled into oil bodies and protein bodies

A recombinant polypeptide containing the precursor protein of a sesame storage protein, 2S albumin, fused to the C-terminus of a sesame oleosin was expressed in transgenic rice seeds under the control of a rice glutelin promoter. The recombinant polypeptide of 32 kDa, equivalent to the resultant molecular mass of sesame oleosin (15 kDa) and prepro-2S albumin (17 kDa), was detected in the endoplasmic reticulum fraction of maturing transgenic rice seeds, but not in the purified oil bodies or the soluble extract of transgenic seeds. However, sesame oleosin presumably fused with a 2 kDa C-terminal appendix originating from the signal sequence of prepro-2S albumin, was found in the purified oil bodies, and mature sesame 2S albumin apparently processed into two subunits (9 and 4 kDa) linked by disulfide bonds was detected in extracts of transgenic seeds. Immunogold labeling revealed that the sesame oleosin and 2S albumin were separately located in oil bodies and protein bodies of embryo cells of transgenic rice seeds. While sesame 2S albumin was also detected in protein bodies of endosperm cells of transgenic seeds, the co-expressed sesame oleosin, probably degraded due to the lack of oil bodies in this tissue, and was not detected. The results provide a new technique for introducing two recombinant polypeptides separately into rice oil bodies and protein bodies from one expression construct.     

Effect of Chelated Vanadium Spray on Concentration of Vanadium and Organic Compounds in Tea Shoots

The study aimed to develop vanadium tea products and evaluated the potential of chelated vanadium （V） absorption by tea shoots and effect of vanadium accumulation on tea quality during the first crop season.Chelated V application with three times foliar sprays at 5 days intervals starting from 15 days before plucking showed a significant increase in V content of new young shoots,which was much effective at higher concentration.However,one or two times sprays had no increase in V content regardless of spray concentration compared to non-treated.Despite V accumulation in the treated at 3 to 9 times higher that of than the non-treated plants,there were no significant changes in contents of total amino acids,theanine,caffeine,total polyphenols,crude fiber,and cathechins between the treated and the non-treated.     

Observations on growth, sexual maturity and spawning performance of pond-reared Penaeus merguiensis

This 12‐month preliminary study investigated the development of sexual characters, primary sexual maturity, ovarian maturity and spawning performance of pond‐reared Penaeus merguiensis in relation to culture conditions in south‐east Queensland, Australia. Post‐larvae of P. merguiensis were produced and cultured in two 60‐m³ tanks during the first 14 weeks. Before winter, they were harvested and stocked in three different overwintering facilities: a 200‐m² covered pond, two 60‐m³ outdoor tanks and a 15‐m³ indoor, recirculated tank at a stocking density of 10 individuals m^?2. The development of sexual characters was found to be similar to that reported previously in wild P. merguiensis. Males matured at younger ages and smaller sizes than females. Overall, the average size at primary sexual maturity of pond‐reared P. merguiensis was 23.1 mm carapace length for males (possessed spermatophores) and 29.3 mm for females (being impregnated). Water temperature and the availability of natural food strongly influenced prawn growth, maturity rate and their subsequent spawning performance. Growth, maturity rate and spawning performance of prawns in the covered pond were significantly higher than in the other overwintering facilities. Prawns started mating at 6–7 months, reached full ovarian maturation and spawned as early as about 8 (peaked at 9–11) months from hatching, producing high fecundity and viable larvae. There was a strong relationship (P < 0.001) between prawn size and fecundity. The results of this study suggest a potential for using pond‐reared broodstock P. merguiensis for hatchery production and for domestication or selective breeding programmes.     

Estimating canopy cover from color digital camera image of rice field

Canopy cover (CC) is a good predictor variable for plant growth parameters such as leaf area index and aboveground biomass. A nondestructive, low-cost, and convenient method is presented for estimating CC using digital camera image analysis. CC was estimated by the ratio of plant pixels to total pixels of digital camera image of rice field. To determine the criteria for segmenting the rice plant from variable soil background, three mosaic images for rice plant, flooded/bare soil, and algae-infested background were prepared from digital camera images that were taken in various field conditions. An image analysis program was developed in Visual Basic to extract red, green, and blue (RGB) features from the mosaic images, calculate RGB-based color indices, and compute the minimum segmentation error for separating rice plant from background. When judged by the segmentation error, modified excessive green index (MEGI) showed the highest potential for segmenting rice plant from flooded/bare soil background, followed by normalized green (g) and excessive green index (EGI). At the threshold MEGI value of 0.03, the segmentation error was the lowest as 0.13%. Any single index considered was not satisfactory in segmenting rice plant from algae-infested background. However, a discriminant function of 1.2553EGI + 0.01735G − 0.01474B was successful in segmenting rice plant from flooded/bare soil and algaeinfested background with segmentation errors of 0.34 and 1.17%, respectively. CC for four rice varieties from tillering to booting stage was estimated based on the threshold value of MEGI and discriminant function and also manually using commercial software. Both estimates of CC showed good relationship of r² = 0.94, suggesting that a digital camera could be used efficiently for measuring the CC of rice field.     

Viewpoints on synergising ASEAN academic visibilities through research collaboration and the establishment of an ASEAN Citation Index Database1

This opinion article expresses two key viewpoints regarding the options for Association of South‐East Asian Nations (ASEAN) universities in pursuit of fulfilling the demand for greater research visibility and academic reputation. The first viewpoint outlines the importance of promoting research collaboration among ASEAN researchers and their international peers in increasing the visibility and impact of ASEAN research. The second viewpoint examines the ASEAN research characteristics, the challenges and existing best practices of its journal publishing landscape, the potential role of non‐ASEAN international journals in improving the profile of ASEAN research and explores the needs and benefits of establishing an ASEAN Integrated Journal Publishing Network (IJPN). It is through these combined approaches, we believe, that effective policy change, the standardisation of publishing structure, procedures, and systems to drive journal development, improvement of journal quality, and establishment of a consistent framework for measuring researcher performance will result. This article also includes a proposal for the IJPN structure and implementation plan, and highlights the key benefits of taking a collaborative approach to achieving this common goal.