A New and Simple Technique for the Isolation of Plasma Membrane Lipids from Root-Tips

It has been suggested that plasma membrane (PM) lipids play a major role in aluminum (Al) tolerance; however, no direct investigations have been carried out using PM lipids from root-tips. Here we report a new technique for PM isolation as an alternative to the laborious two-polymer phase partitioning method that is commonly applied, as follows: 1) separation of protoplasts from 1-cm root-tip portions by enzymatic digestion, 2) attachment of the purified protoplasts to glass plates coated with polylysine, 3) preparation of PM ghosts by successive burst of the attached protoplasts using three separate buffer solutions (25 mM PIPES, 5 mM EDTA, and 2 mM MgCl₂, at pH 7.0) with slow stirring for 60 s. The PMs were confirmed to be devoid of organelle membranes by fluorescence microscopy, thin layer chromatography (TLC) and western blot analysis. The PM lipids obtained were found to be useful for studies on their differential permeability and lipid composition between lines of triticale or cultivars of maize under Al stress.     

UV-B irradiation retards chlorophyll degradation in lime (Citrus latifolia Tan.) fruit

Peel yellowing is a major postharvest problem of lime fruit. Research was conducted to control peel yellowing by UV-B irradiation. Mature green lime fruit were irradiated with UV-B doses at 0 (control), 8.8, and 13.2 kJ m^?2 and then stored at 25 °C in darkness. UV-B treatment at 8.8 kJ m^?2 efficiently delayed the decrease of chlorophyll content. A high level of chlorophyllide a accumulated in mature green fruit and then gradually decreased with the progress of peel yellowing. The chlorophyllide a level was higher in 8.8 kJ m^?2 UV-B-treated fruit than it was in the controls. The pheophorbide a level declined in lime fruit treated with 8.8 kJ m^?2 UV-B, especially during the development of yellowing. In addition, the pheophytin a level increased by 8.8 kJ m^?2 UV-B treatment at the late period of storage. We concluded that UV-B treatment effectively suppressed chlorophyll degradation in mature green lime during storage, which suggests that UV-B irradiation is a usable method for prolonging the postharvest life of lime fruit.     

Mitochondrial Targeting in an Anti-Austerity Approach Involving Bioactive Metabolites Isolated from the Marine-Derived Fungus Aspergillus sp.

The tumor microenvironment is a nutrient-deficient region that alters the cancer cell phenotype to aggravate cancer pathology. The ability of cancer cells to tolerate nutrient starvation is referred to as austerity. Compounds that preferentially target cancer cells growing under nutrient-deficient conditions are being employed in anti-austerity approaches in anticancer drug discovery. Therefore, in this study, we investigated physcion (1) and 2-(2′,3-epoxy-1′,3′,5′-heptatrienyl)-6-hydroxy-5-(3-methyl-2-butenyl) benzaldehyde (2) obtained from a culture extract of the marine-derived fungus Aspergillus species (sp.), which were isolated from an unidentified marine sponge, as anti-austerity agents. The chemical structures of 1 and 2 were determined via spectroscopic analysis and comparison with authentic spectral data. Compounds 1 and 2 exhibited selective cytotoxicity against human pancreatic carcinoma PANC-1 cells cultured under glucose-deficient conditions, with IC₅₀ values of 6.0 and 1.7 µM, respectively. Compound 2 showed higher selective growth-inhibitory activity (505-fold higher) under glucose-deficient conditions than under general culture conditions. Further analysis of the mechanism underlying the anti-austerity activity of compounds 1 and 2 against glucose-starved PANC-1 cells suggested that they inhibited the mitochondrial electron transport chain.     

Experimental study on the influence of dissolved organic matter in water and redox state of bottom sediment on water quality dynamics under anaerobic conditions in an organically polluted water body

To understand aquatic environmental deterioration due to the anoxic state in an organically polluted water body, water quality dynamics under anaerobic conditions were examined through beaker-scale water quality monitoring. This study focused on the dynamic properties of NO₃–N, NH₄–N, PO₄–P, and sulfide from the biochemical reactions point of view, and based on anaerobic respiration activities, such as denitrification, iron reduction, and sulfate reduction. The specific aims of this study were to quantitatively estimate the impacts of the oxidative/reductive state of the sediment surface and the high/low concentrations of dissolved organic matter on the dynamic properties of water quality under anaerobic conditions. The beaker-scale water quality monitoring was carried out through continuous measurements of dissolved oxygen and oxidation–reduction potential (ORP), as well as periodic observations of water quality parameters for six cases that are composed from combinations of three experimental conditions: (1) concentration of dissolved organic carbon (DOC); (2) redox state of the sediment; and (3) concentration of NO₃–N. As a result, the temporal changes in ORP under anaerobic conditions exhibited a five-step process of decline without these conditions. Also, high DOC concentrations and oxidative states of the bottom mud accelerated the release of PO₄–P and sulfide generation through promoting biological iron reduction and sulfate reduction, because these conditions increase respiratory substrates for anaerobic microorganisms, such as iron and sulfate-reducing bacteria. It was concluded that our results would provide important information about the mechanisms of aqueous environmental deterioration due to organic pollution in closed water bodies.     

A case report of a renal mixed epithelial and stromal tumor in a heterozygous S1P2 receptor deficient mouse

We report a case of mixed epithelial and stromal tumor of the kidney (MESTK) in a 32-week-old heterozygous sphingosine 1-phosphate-2 (S1P2) receptor deficient female mouse. A white solid mass replacing the left kidney was observed at the left retroperitoneal wall. Histologically, the tumor mass consisted of dimorphic cellular components of epithelial and stromal cells. Epithelial cells formed various sized irregular-shaped tubular structures resembling renal tubules surrounded by stromal cells. Immunohistochemically, epithelial cells were positive for cytokeratin, while stromal cells showed positive immunoreactivity with alpha-smooth muscle actin as well as vimentin. Based on the morphological and immunohistochemical findings, this tumor was diagnosed as a MESTK.     

Estimation of water quality dynamics under long-term anoxic state in organically polluted reservoir by field observations and improved ecosystem model

In closed water bodies with significant organic pollution, anoxification due to thermal stratification leads to the elution of nitrogen and phosphorus from the bottom sediment and the generation of sulfide, resulting in further degradation of the water environment. This study focuses on the water quality dynamics in an organically polluted reservoir exhibiting long-term anoxification using two approaches: (1) field observations of seasonal changes in vertical profiles of dissolved oxygen, nitrogen, phosphorus, and sulfide and (2) construction of a water quality prediction model based on an ecosystem model incorporated with anaerobic biochemical processes. Iron and sulfate reduction occurred simultaneously because nitrate–nitrogen was reduced by denitrifying bacteria after the anoxification, and iron reduction became the main factor of the increase in ammonium–nitrogen and phosphate–phosphorus. The redox state of the bottom sediment surface, when anoxification began to occur, greatly affected the water quality dynamics caused by gradual reductive reactions under anaerobic conditions. Furthermore, the calculation accuracy of ammonium–nitrogen, phosphate–phosphorus, and sulfide was highly improved by modifying the conventional model based on the field observations. The characteristics of water quality under anaerobic conditions were sufficiently reflected in the upgraded ecosystem model. The proposed water quality prediction model could be used to quantitatively estimate the water environment dynamics in organically polluted water bodies. The model could be developed further in the future to solve the problems caused by long-term anoxification.     

Participatory system for water management in the Toyogawa Irrigation Project, Japan

In principle, participatory irrigation management (PIM) means the involvement of irrigation users in all aspects at all levels of irrigation management. In practice, all over the world efforts are being made to realize the principles. However, in the execution of PIM, role sharing between farmers and government is a serious problem, and thus a clear method and ideas are needed to improve PIM. In particular, a broad discussion of role sharing is demanded. This article illustrates how the Japanese way of role sharing in PIM is realized based on the case of the Toyogawa Irrigation Project. Organizationally, the project is jointly managed by five entities, including both the public sector and the farmers’ organizations. These entities have clearly divided their functional roles, with the ultimate decision power in all aspects of irrigation management given to organized farmers. The power is realized either directly or through the land improvement districts’ representative system depending on the levels of the irrigation system. The public entity provides coordination support to create a transparent forum of discussion together with scientific information for farmers’ understanding and decision making. The participatory institutional line-up of this project enables the upland areas that suffered periodically from water deficits.     

Optimal gate operation of a main drainage canal in a flat,low-lying,agricultural area using a tank model

Chiyoda basin is located in Saga Prefecture in Kyushu Island, Japan, and lies next to the tidal compartment of the Chikugo River to which the excess water in the basin is drained away. Chiyoda basin has a total area of about 1,100 ha and is a typical flat and low-lying paddy-cultivated area. The main problem in this basin is the appropriate operation of drainage structures during and after flood events in order to minimize the inundation damages for crop yield and to fulfill the irrigation requirement in the irrigation period. This paper presents a mathematical model of a drainage system in Chiyoda basin for calculating the flood inundation and optimizing the operation of gates in a main drainage canal. First, the algorithm of gate operation was simulated and the drainage model was then evaluated by comparing the simulated water levels with those observed during an actual rainfall event. The results show that the observed and simulated water levels are in good agreement, indicating that the proposed model is applicable for drainage and inundation analyses in flat, low-lying paddy-cultivated areas. Second, the optimization of gate operation was investigated by trial and error method using a stochastic rainfall time series with a return period of 30 years and the tidal conditions of spring and neap tides in the Chikugo River. Comparing a total inundation time, a total inundation area and maximum inundation depth in the paddy tanks at the upstream and the downstream ends, it was concluded that the present operation based on the gate operators’ experience was almost the optimal one, and the sooner start of opening operation and the later start of closing operation within the operationality of check gates were recommended to minimize the inundation damage. The present operation could be able to minimize the total inundation time, the total inundation area and the maximum inundation depths in paddy tanks and to meet fully both the drainage and the irrigation requirements.     

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.