Wayfinding with a GPS-based mobile navigation system: A comparison with maps and direct experience

This study examined the effectiveness of a Global Positioning System (GPS)-based mobile navigation system in comparison to paper maps and direct experience of routes, by focusing on the user's wayfinding behavior and acquired spatial knowledge. Based on information received from one of these three media, participants walked six routes finding the way to goals. Results showed that GPS users traveled longer distances and made more stops during the walk than map users and direct-experience participants. Also, GPS users traveled more slowly, made larger direction errors, drew sketch maps with poorer topological accuracy, and rated wayfinding tasks as more difficult than direct-experience participants. Characteristics of navigation with these three learning media and possible reasons for the ineffectiveness of the GPS-based navigation system are discussed.     

Overexpression of NADH oxidase gene from Deinococcus geothermalis in Escherichia coli

When using stable enzyme genes from a thermophile to create a biosensor in Escherichia coli, it is vital that these genes be overexpressed in order to provide a sufficient supply of enzymes. In this study, overexpression of the NADH oxidase (Nox) gene from the thermophile Deinococcus geothermalis was successfully achieved with the aim of creating a stable biosensor active at room temperatures. To do so, modification of 10 nucleotides, GAAATTAACT, upstream of the start codon of the Nox gene was necessary.     

Overexpression of NADH oxidase gene from Deinococcus geothermalis in Escherichia coli

When using stable enzyme genes from a thermophile to create a biosensor in Escherichia coli, it is vital that these genes be overexpressed in order to provide a sufficient supply of enzymes. In this study, overexpression of the NADH oxidase (Nox) gene from the thermophile Deinococcus geothermalis was successfully achieved with the aim of creating a stable biosensor active at room temperatures. To do so, modification of 10 nucleotides, GAAATTAACT, upstream of the start codon of the Nox gene was necessary.     

Natural attenuation is enhanced in previously contaminated and coniferous forest soils

Purpose  

Prevalence of organic pollutants or their natural analogs in soil is often assumed to lead to adaptation in the bacterial community, which results in enhanced bioremediation if the soil is later contaminated. In this study, the effects of soil type and contamination history on diesel oil degradation and bacterial adaptation were studied.     

Layer of organic pine forest soil on top of chlorophenol-contaminated mineral soil enhances contaminant degradation

Chlorophenols, like many other synthetic compounds, are persistent problem in industrial areas. These compounds are easily degraded in certain natural environments where the top soil is organic. Some studies suggest that mineral soil contaminated with organic compounds is rapidly remediated if it is mixed with organic soil. We hypothesized that organic soil with a high degradation capacity even on top of the contaminated mineral soil enhances degradation of recalcitrant chlorophenols in the mineral soil below. We first compared chlorophenol degradation in different soils by spiking pristine and pentachlorophenol-contaminated soils with 2,4,6-trichlorophenol in 10-L buckets. In other experiments, we covered contaminated mineral soil with organic pine forest soil. We also monitored in situ degradation on an old sawmill site where mineral soil was either left intact or covered with organic pine forest soil. 2,4,6-Trichlorophenol was rapidly degraded in organic pine forest soil, but the degradation was slower in other soils. If a thin layer of the pine forest humus was added on top of mineral sawmill soil, the original chlorophenol concentrations (high, ca. 70 μg g^?1, or moderate, ca. 20 μg g^?1) in sawmill soil decreased by >40 % in 24 days. No degradation was noticed if the mineral soil was kept bare or if the covering humus soil layer was sterilized beforehand. Our results suggest that covering mineral soil with an organic soil layer is an efficient way to remediate recalcitrant chlorophenol contamination in mineral soils. The results of the field experiment are promising.     

Changes in TcpA gene frequency explain 2,4,6-trichlorophenol degradation in mesocosms

Soils are often polluted by chlorophenols in timber production areas in the northern hemisphere. The tcpA gene encodes the first step of 2,4,6-trichlorophenol (246-TCP) degradation. We tested tcpA gene frequency in three natural pristine soils with different 246-TCP degradation capacity. Gene tcpA frequency increased more in spiked than non-spiked 10-L pails containing coniferous humus soil with high degradation capacity, in contrast to soils where degradation was slower. As the soil in each mesocosm originated from a spatially separate field plot, changes in tcpA gene frequency affected 246-TCP degradation over a range of soil origins. This indicates that the abundance of and changes in tcpA gene frequency could be utilized in estimating the efficacy of natural attenuation and biostimulation treatments in controlled conditions.     

Early life history of tropical Anguilla leptocephali in the western Pacific Ocean

In order to examine the early life-history characteristics of tropical eels, otolith microstructure and microchemistry were examined in leptocephali of Anguilla bicolor pacifica (27.6-54.1 mm TL, n=20) and A. marmorata (22.0-47.3 mm TL, n=8) collected during a cruise in the western Pacific. A. bicolor pacifica occurred between 10°N and 15°N in the west and between 5°S and 10°N farther to the east. A. marmorata also occurred in two different latitudinal ranges in the Northern (15-16°N) and Southern Hemispheres (3-15°S) of the western Pacific. The increment widths in the otoliths of these leptocephali increased between the hatch check (0 days) and about an age of 30 days in both species, and then gradually decreased toward the otolith edge. Otolith Sr:Ca ratios showed a gradual increase from the otolith center to the edge. The ages of A. bicolor pacifica and A. marmorata leptocephali ranged from 40 to 128 days and from 38 to 99 days, respectively. Growth rates of A. bicolor pacifica and A. marmorata leptocephali ranged from 0.33 to 0.71 mm day^-1 and from 0.45 to 0.63 mm day^-1, respectively. These leptocephali had estimated growth rates that were spread out throughout most of the reported range of growth rates of the leptocephali of the temperate species, the Japanese eel and the Atlantic eels. Differences in the spatial distribution in relation to current systems, and the age and size compositions of the leptocephali of A. bicolor pacifica and A. marmorata suggested different spawning locations for these two species.     

Heritable pheromone blend variation in a local population of the butterbur borer moth Ostrinia zaguliaevi (Lepidoptera: Crambidae)

Summary. In a local population of Ostrinia zaguliaevi Mutuura & Munroe (Lepidoptera: Crambidae), extensive variation was found in the blend ratio of three sex pheromone components, (Z)-9-tetradecenyl acetate (Z9-14:OAc, 10.2-63.8%), (Z)-11-tetradecenyl acetate (Z11-14:OAc, 32.2-86.8%), and (E)-11-tetradecenyl acetate (E11-14:OAc, 2.1-11.9%). The variation was observed over a three-year period (2002-2004). Mother-daughter regression analyses have shown that although the heritability of the minor component E11-14:OAc was not significant, the heritability of the proportions of Z9-14:OAc and Z11-14:OAc were substantial (0.5–0.6). In artificial selection experiments, the mean % Z9-14:OAc in the sex pheromone changed significantly within three generations (37% in the control line, 48 and 52% for two lines selected for increase, and 23 and 30% for two lines selected for decrease). Despite these changes, the amounts of fatty acyl pheromone precursors, (Z)-9-, (Z)-11- and (E)-11-tetradecenoate, in the pheromone gland were not significantly affected by the selection. Taken together, variation in the pheromone blend of O. zaguliaevi is likely to be attributable to a few genes involved in the reduction or acetylation of fatty acyl pheromone precursors, the last two steps in pheromone biosynthesis.     

Female sex pheromone of Ostrinia orientalis – throwing a light on the relationship between O. orientalis and the European corn borer, O. nubilalis

Summary. The sex pheromone of Ostrinia orientalis (Lepidoptera: Crambidae) was analyzed by gas chromatography–electroantennographic detection (GC–EAD), GC–mass spectrometry and a series of bioassays. Three EAD-active compounds were detected in the female sex pheromone gland extract, and identified as tetradecyl acetate (14:OAc), (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (E)-11-tetradecenyl acetate (E11-14:OAc). The titers (ratio) of 14:OAc, Z11-14:OAc and E11-14:OAc in 3-day-old virgin females were 0.49 ng (10), 4.86 ng (98) and 0.10 ng (2), respectively. In a wind-tunnel bioassay, the 98:2 blend of Z11- and E11-14:OAc, but not Z11-14:OAc alone, elicited the same male behavioral responses as virgin females and crude gland extracts. 14:OAc was inactive by itself, and did not show any synergistic effect on the binary blend. Field trapping experiments also confirmed the attractiveness of the binary blend to O. orientalis males. Based on these results, we concluded that the sex pheromone of O. orientalis is a 98:2 mixture of Z11-14:OAc and E11-14:OAc. This sex pheromone is very similar to that of the Z-type European corn borer, O. nubilalis. The present finding raises the question of whether O. orientalis , which is indistinguishable from O. nubilalis based on external morphology, is a biologically distinct species independent from O. nubilalis.     

Mutagenicity of polyaromatic hydrocarbons by chemical models for cytochrome P450 in Ames assay

DNA damage is an important step in carcinogenesis. The Ames assay is a short-term screening of carcinogens that induce DNA damage. Most carcinogens require enzymatic activation through oxidation by cytochrome P450 (CYP450) in the presence of S9 mix. A combination of iron (Fe)(III) porphyrin and an oxidant is also able to oxidize compounds as an alternative metabolic pathway to CYP450. Previously it was reported that a chemical model containing a water-soluble 5,10,15,20-tetrakis(1-methylpyridinium4-yl)porphyrinatoiron(III) chloride (4-MPy) and tert-butyl hydroperoxide (t-BuOOH) activated aromatic amines and amides. In this study, a chemical model composed of an Fe porphyrin, water-insoluble 5,10,15,20-tetrakis(pentafluorophenyl)porphyrinatoiron(III) chloride (F₅P) or water-soluble 4-MPy was optimized with an oxidant – t-BuOOH, magnesium monoperoxyphthalate (MPPT), or iodosylbenzene (PhIO). Subsequently the mutagenicity of benzo[a]pyrene (B[a]P) and chrysene in Salmonella typhimurium TA strains was compared. B[a]P was activated by a combination of F₅P or 4-MPy plus MPPT or PhIO in S. typhimurium TA1538. The B[a]P-induced mutagenicity with F₅P plus oxidant was higher than 4-MPy plus oxidant. Mutagenicity of chrysene, a tetracyclic aromatic hydrocarbon, was not detected in the presence of F₅P/PhIO in S. typhimurium TA98, but was activated in the presence of F₅P/MPPT. The F₅P/MPPT activated other polyaromatic hydrocarbons (PAH) in the S. typhimurium TA98 assay including dibenz[a,c]anthracene, dibenz[a,h]anthracene, 3-methylcholanthrene, and benzo[a]anthracene. The results indicated that the F₅P/MPPT was the most efficient model for detecting PAH-induced mutagenicity in the Ames assay.