Neutralization of Acid Droplets on Plant Leaf Surfaces

Sulfuric acid mist exposure of bush bean leaves at a low rate of precipitation suggested that acid on the leaf surface was neutralized by cations leached from leaf tissues and that Ca-S compounds were accumulated on the leaf surface (Kohno, 1994). This report summarizes visual observations of the neutralization process of acid on leaf surfaces as determined by a pH-imaging microscope. Small droplets of sulfuric acid were placed on the adaxial leaf surface and allowed to air dry under laboratory conditions. Droplets (0.1 µl) of sulfuric acid took about 7–8 minutes to dry. Leaf samples were cut at various times after the acid droplets dried. The adaxial leaf surface was placed on the pH-adjusted agar film layer on the pH-imaging sensor of the microscope. Hydrogen ions dispersed into the film layer and resulting pH distributions were visualized as pH distribution patterns. The size of the acidic area generated became smaller with time after the acid was added and allowed to dry. Results indicate that leaves could neutralize the surface acid probably by ion exchange with cations from their surface tissues and could recover from strong temporary acid stress imposed by acid rain or acid fog in a relatively short period of time. Our findings indicate that acidic precipitation at current acidity levels does not pose a direct threat to plants.     

Cell corpse engulfment mediated by C. elegans phosphatidylserine receptor through CED-5 and CED-12

During apoptosis, phosphatidylserine, which is normally restricted to the inner leaflet of the plasma membrane, is exposed on the surface of apoptotic cells and has been suggested to act as an "eat-me" signal to trigger phagocytosis. It is unclear how phagocytes recognize phosphatidylserine. Recently, a putative phosphatidylserine receptor (PSR) was identified and proposed to mediate recognition of phosphatidylserine and phagocytosis. We report that psr-1, the Caenorhabditis elegans homolog of PSR, is important for cell corpse engulfment. In vitro PSR-1 binds preferentially phosphatidylserine or cells with exposed phosphatidylserine. In C. elegans, PSR-1 acts in the same cell corpse engulfment pathway mediated by intracellular signaling molecules CED-2 (homologous to the human CrkII protein), CED-5 (DOCK180), CED-10 (Rac GTPase), and CED-12 (ELMO), possibly through direct interaction with CED-5 and CED-12. Our findings suggest that PSR-1 is likely an upstream receptor for the signaling pathway containing CED-2, CED-5, CED-10, and CED-12 proteins and plays an important role in recognizing phosphatidylserine during phagocytosis.     

Use of batch leaching tests to quantify arsenic release from excavated urban soils with relatively low levels of arsenic

Purpose

In Japan, the excavated soils produced from constructions projects, which contain relatively low levels of arsenic (As), are considered as a potential concern if they could release significant amount of As to the environment. The aim of this study was to investigate the As leaching from excavated alkaline soils and, in particular, the influence of drying methods, pH of extracting solution, and consecutive washing on As leaching from these soils.

Materials and methods

Four excavated alkaline soils obtained from different construction sites in Tokyo, Japan, were used in this study. The soils were pretreated by three drying methods (air-dried, 40 °C-dried, and freeze-dried). Sequential extraction procedure was applied to partition As into five operationally defined chemical fractions. Batch leaching tests (initial pH-controlled leaching test and consecutive washing test) were conducted to investigate the As release under different leaching conditions.

Results and discussion

The As contents in the four soils were 9.22, 79.4, 6.75, and 11.7 mg kg^?1, respectively, and As was primarily associated with the residual phase. Arsenic leaching was strongly dependent on the extracting solution pH values. Strongly acidic extracting solution (pH 2) led to circumneutral leachates and limited As mobility, whereas the strong alkaline-extracting solution (pH 12) greatly enhanced the As release from these soils. The consecutive washing test results revealed a long-term release of As from these excavated soils. The pollution potential indices (PPIs) were successfully used to evaluate the pollution threat of As leaching from excavated soils. In addition, different drying methods resulted in variations in the short- and long-term release of As from these excavated soils.

Conclusions

The results revealed that the soil pretreatment and the leaching conditions should be considered if we want to use batch tests for the contamination assessment of excavated urban soils from construction projects. Different drying methods and single extraction may lead to misestimation of the As pollution level. High extraction efficiency with strong alkaline-extracting solution (pH 12) reveals that it could potentially be used to wash As from excavated alkaline soils.

     

Genotyping of the <Emphasis Type="Italic">SiDREB2</Emphasis> gene in worldwide foxtail millet (<Emphasis Type="Italic">Setaria italica</Emphasis> (L.) P. Beauv.) genetic resources with special attention to Indian landraces

We genotyped Setaria italica Dehydration-responsive element-binding 2 (SiDREB2) gene, which had been reported to be associated with dehydration stress tolerance, in 588 accessions of foxtail millet from various parts of Eurasia and other regions by a dCAPS marker. Of these, 480 accessions were genotyped in ribosomal DNA (rDNA), polyphenol oxidase (PPO) gene and Heading date 1 (HD1) gene in our previous studies, and 108 accessions from India were newly used in this study and genotyped in these genes in addition to the SiDREB2 gene. We compared the geographical distribution of the SiDREB2 genotypes with that of these three genes. Accessions from countries in South Asia including India and Sri Lanka were the most variable in the SiDREB2 gene followed by Korean accessions and Japanese accessions, suggesting that Indian accessions and East Asian accessions are useful as genetic resources for dehydration stress tolerance. This study also showed that although Indian accessions are not so diverse in rDNA and in transposon display markers previously studied, they are diverse in adaptive genes such as SiDREB2, PPO and HD1 genes.     

Effect of Steel Slag to Improve Soil Quality of Tsunami-Impacted Land while Reducing the Risk of Heavy Metal Bioaccumulation

After the tsunami caused by the Great East Japan Earthquake, marine sediment was taken from the sea bottom and deposited over local agricultural fields. The marine sediment already contained an unknown amount of heavy metals, due to anthropogenic activities prior to the tsunami, which might affect plants, animals, and humans. Furthermore, soil salinity in tsunami-inundated land greatly increased. Three different amounts of steel slag were employed as pretreatment agent in order to improve agricultural soil quality. The soil samples treated with 2% of steel slag present a remarkable increase of A. thaliana biomass production with low BCF and TF values for most of the heavy metals. It was concluded that steel slag pretreatment used in the tsunami-inundated agricultural lands produced a noteworthy improvement in soil quality which lead to a positive stimulative effect on plant growth, and the slag addition treatment proved to be a promising treatment that might be used for phytostabilization of slightly contaminated soils.     

Sorafenib inhibits tumor cell growth and angiogenesis in canine transitional cell carcinoma

Canine transitional cell carcinoma (cTCC) is the most common naturally occurring bladder cancer and accounts for 1–2% of canine tumors. The prognosis is poor due to the high rate of invasiveness and metastasis at diagnosis. Sorafenib is a multi-kinase inhibitor that targets rapidly accelerated fibrosarcoma (RAF), vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, VEGFR-3, platelet-derived growth factor receptor-β (PDGFR-β), and KIT. In previous studies, a somatic mutation of B-rapidly accelerated fibrosarcoma (BRAF) and expressions of VEGFR-2 and PDGFR-β were observed in over 80% of patients with cTCC. Therefore, in this study, we investigated the anti-tumor effects of sorafenib on cTCC. Five cTCC cell lines were used in the in vitro experiments. All five cTCC cell lines expressed VEGFR-2 and PDGFR-β and sorafenib showed growth inhibitory effect on cTCC cell lines. Cell cycle arrest at the G0/G1 phase and subsequent apoptosis were observed following sorafenib treatment. In the in vivo experiments, cTCC (Sora) cells were subcutaneously injected into nude mice. Mice were orally administered with sorafenib (30 mg/kg daily) for 14 days. Sorafenib inhibited tumor growth compared to vehicle control. The necrotic area in the tumor tissues was increased in the sorafenib-treated group. Sorafenib also inhibited angiogenesis in the tumor microenvironment. Thus, sorafenib may be potential therapeutic agent for cTCC via its direct anti-tumor effect and inhibition of angiogenesis.     

Relationship between the Lactic Acid Content and Sour Taste of Broiler Broth and the Broth of Choshu-Kurokashiwa—a Japanese Jidori Chicken

The present study aimed to determine whether lactic acid content is associated with the intensity of the sour taste of Choshu-Kurokashiwa broth. Chicken broth was prepared using breast (pectoralis major) and leg (thigh + drumstick) meat of male and female Choshu-Kurokashiwa and broilers. These broths were assessed by a screened and trained panel and analyzed for sour taste substances (lactic, citric, pyruvic, malic, succinic, acetic, phosphoric, aspartic, and glutamic acids) and pH. The sensory sour taste was significantly higher in the Choshu-Kurokashiwa breast broth than in the broiler breast broth (P>0.001), and no significant difference was observed in the leg broths among the breeds (P<0.05). Choshu-Kurokashiwa breast broth had a significantly higher lactic acid content than broiler breast broth (P<0.001). The leg meat broth of male Choshu-Kurokashiwa had a significantly lower lactic acid content than that of female Choshu-Kurokashiwa and broiler leg meat (P<0.01). The sensory sour taste score was significantly and positively correlated with lactic acid content in the breast broth (P<0.001), but not in the leg broth (P<0.1). No other organic acids were detected. Phosphoric acid and glutamic acid contents were higher in broiler broth than in Choshu-Kurokashiwa broth for both breast and leg meat (P<0.001). In the breast broth, the aspartic acid content was not significantly different (P>0.1), and in the leg broth, it was higher in broiler and female Choshu-Kurokashiwa broth than in male Choshu-Kurokashiwa broth (P<0.001). The present study suggests that high lactic acid content contributes to the sour taste of the Choshu-Kurokashiwa breast broth and demonstrated that the lactic acid content is an essential indicator for determining the sour taste of Choshu-Kurokashiwa breast meat.