Electrochemical reduction of organohalogen compound by noble metal sintered electrode

1,2,3-Trichlorobenzene (1,2,3-TCB) was used as a model sample of persistent organic pollutants (POPs) which was dechlorinated by a closed electrochemical reduction system under an inert gas atmosphere. The effect of the electrode material was examined in the reaction. Dechlorination yields in different type of cathode electrodes using sintered RuO2 (major)/Pt/PdO, sintered Pt(major)/IrO2/RuO2, sintered RuO2, sintered PdO, sintered Pt, sintered PdO/Pt, sintered Pd/Pt and plain Pd plate were 91%, 81%, 59%, 96%, 53%, 97%, 82% and 70% respectively, at reaction times of 60 or 120 min. The reaction was exothermic after initially starting at room temperature. This electrochemical reduction system was friendly technology for environment using cation exchange membrane, supplying sodium ions from sodium hydroxide solution as anolyte. Trace amounts of dichlorobenzene, as products of stepwise dechlorination, were observed with different pathways, depending on the electrode material. Electrodes with Ru and Pd were selective mainly for meta-position dechlorination, while those with Pt groups selective mainly for ortho-position (o-position) dechlorination. A PdO sintered electrode had an especially high selectivity for meta-position (m-position) dechlorination. The results suggest that dechlorination is an electrocatalytic reduction in this cation supply system.     

Polychlorinated biphenyls in preserved human umbilical cords

Congener-specific PCB analyses were carried out on preserved umbilical cord samples. Total PCB concentrations were higher in the umbilical cords of subjects born in the 1960s and 70s than in those born more recently. Total PCB concentrations in the cords from 3 groups of siblings showed no linear relationships between birth order and total PCB concentration. The congener and homologue compositions of PCBs in the umbilical cords of one group of siblings were similar to those of commercial PCB products.     

TCDD (2,3,7,8-tetrachlorodibenzo-P-dioxin) causes reduction in glucose uptake through glucose transporters on the plasma membrane of the guinea pig adipocyte.

A single dose of 2,3,7,8-TCDD (1 micrograms/kg, i.p. injection) resulted in a significant decrease in cellular 3-O-methyl-[3H]-glucose uptake by guinea pig adipose tissue and pancreas after 24 hours. An in situ tissue culture study in which pieces of adipose tissue were incubated with 10(-8)M TCDD showed a time-dependent decrease in glucose uptake. Reconstitution of adipocyte plasma membrane from tested or control animals into artificial liposomes also resulted in this difference in glucose uptake. Binding of [3H]-cytochalasin B, a specific inhibitor of glucose transporter proteins, was significantly lower in acetone-ether powder preparations of TCDD-treated adipose tissue than from controls, suggesting that the total titer of these proteins is decreased by TCDD. Finally, the relevance of these results to glucose or lipid metabolism was tested. Lipoprotein lipase (LPL) activity of guinea pig adipose tissue was decreased after 8 hours of in situ incubation with TCDD indicating that glucose uptake was depressed at an earlier time point. These findings may contribute to a better understanding of dioxin-induced "wasting syndrome".     

Assessment of the rhizosphere competency and pentachlorophenol-metabolizing activity of a pesticide-degrading strain of Trichoderma harzianum introduced into the root zone of corn seedlings

To develop a dependable approach to introduce laboratory selected, pesticide-degrading microorganisms into soil environments for the purpose of in situ bioremediation, we tested the possibility of utilizing plant rhizospheres as the vehicle. We first established the rhizosphere competency of a strain of the soil fungus Trichoderma harzianum, a biocontrol species well studied by plant pathologists to colonize plant rhizosphere in many parts of the world. The strain we chose, T.h.2023 is resistant to many fungicides, and it has been shown to metabolize several pesticides. Second, we found that it readily metabolized pentachlorophenol (PCP), which is quickly and stochiometrically converted to pentachloroanisole (PCA) in liquid culture. Taking advantage of this specific feature, we have developed a sensitive metabolic marker approach that allowed us to monitor for the continuous presence and activity of this fungal strain in the corn rhizosphere soil in situ over time.     

Analysis of difference in vivo effects of TCDD between c-src +/+ mice, c-src deficient, -/+ and -/- B6, 129-Src(tm 1 sor) mice and their wild-type littermates

Toxicities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were tested on two strains of c-src deficient B6, 129-Src(tm 1 sor) mice, c-src -/+ and c-src -/- and their matched wild-type littermates c-src +/+ mice along with another c-src +/+ mice, from the same genetic lineage, B6, 129-Fos(tm 1 Pa) mice. The most conspicuous effect of c-src deficiency on the toxicity of TCDD appears to be the reduced hepatotoxicity. TCDD-treated c-src deficient mice show only modest degrees of hepatomegaly and triglycerides accumulation as compared to treated wild-type mice.     

Plant origin of Okinawan propolis: honeybee behavior observation and phytochemical analysis

Propolis is a natural resinous product collected by honeybees from certain plants. It has gained popularity as a food and alternative medicine. Poplar and Baccharis are well known as the source plants of European and Brazilian propolis, respectively. However, the propolis from Okinawa, Japan, contains some prenylflavonoids not seen in other regions such as Europe and Brazil, suggesting that the plant origin of Okinawan propolis is a particular plant that grows in Okinawa. To identify the plant origin of Okinawan propolis, we observed the behavior of honeybees as they collected material from plants and caulked it inside the hive. Honeybees scraped resinous material from the surface of plant fruits of Macaranga tanarius and brought it back to their hive to use it as propolis. We collected samples of the plant and propolis, and compared their constituents by high-performance liquid chromatography with a photo-diode array detector. We also compared their 1,1-diphenyl-2-picryl-hydrazyl radical scavenging activity. The chemical constituents and biological activity of the ethanol extracts of the plant did not differ from those of propolis. This indicates directly that the plant origin of Okinawan propolis is M. tanarius. S. K. and J. N. contributed equally to this work.     

Effect of barley chromosome addition on the susceptibility of wheat to feeding by a gall-inducing leafhopper

The maize orange leafhopper Cicadulina bipunctata is distributed widely in tropical and subtropical regions of the Old World and feeds on various Poaceae. The leafhopper is recognized as an important pest of maize in several countries. Adults as well as nymphs of C. bipunctata induce growth stunting and galls characterized by the severe swelling of leaf veins on many cereal crops including wheat, rice, and maize, but do not on barley. To clarify the mechanism of growth stunting and gall induction by C. bipunctata, we used six barley chromosome disomic addition lines of wheat (2H–7H) and investigated the effect of barley (cv. Betzes) chromosome addition on the susceptibility of wheat (cv. Chinese Spring) to feeding by the leafhopper. Feeding by C. bipunctata significantly stunted the growth in 2H, 3H, 4H, and 5H, but did not in 6H and 7H. The degree of gall induction was significantly weaker and severer in 3H and 5H than in Chinese Spring, respectively. These results suggest that barley genes resistant to growth stunting and gall induction exist in 6H and 7H, and 3H, respectively. 5H is considered to be useful for future assays investigating the mechanism of gall induction by this leafhopper because of the high susceptibility to the feeding by C. bipunctata. Significant correlation between the degrees of growth stunting and gall induction was not detected in the six chromosome addition lines and Chinese spring. This implies that these two symptoms are independent phenomena although both are initiated by the feeding of C. bipunctata.