Do corals select zooxanthellae by alternative discharge?

Loss of zooxanthellae (dinoflagellate Symbiodinium) from corals will sometimes lead to mass mortality of corals. To detect and quantify Symbiodinium released from corals, we developed a zooxanthellae “trap” and a quantitative PCR (qPCR) system with Symbiodinium clades A–F-specific primer sets. The trap was attached to a branch or the surface of several wild stony corals, and the water samples within the traps, including released Symbiodinium, were subjected to qPCR. All tested corals released clade C Symbiodinium at estimates of ~5,900 cells h⁻¹ cm⁻² of coral surface. Although all tested Pocillopora eydouxi harboured both clades C and D, some of these colonies released only clade C or released a lesser amount of clade D than that in the tissues. Our Symbiodinium quantification system revealed that wild hermatypic corals constantly release Symbiodinium to the environment. Our result suggests that some corals may discharge certain clades of Symbiodinium alternatively.     

Potential bioremediation of mercury-contaminated substrate using filamentous fungi isolated from forest soil

The use of filamentous fungi in bioremediation of heavy metal contamination has been developed recently. This research aims to observe the capability of filamentous fungi isolated from forest soil for bioremediation of mercury contamination in a substrate. Six fungal strains were selected based on their capability to grow in 25 mg/L Hg2+-contaminated potato dextrose agar plates. Fungal strain KRP1 showed the highest ratio of growth diameter, 0.831, thus was chosen for further observation.Identification based on colony and cell morphology carried out by 18S rRNA analysis gave a 98%match to Aspergillus flavus strain KRP1. The fungal characteristics in mercury(Ⅱ) contamination such as range of optimum pH, optimum temperature and tolerance level were 5.5–7 and 25–35℃ and 100 mg/L respectively. The concentration of mercury in the media affected fungal growth during lag phases. The capability of the fungal strain to remove the mercury(Ⅱ) contaminant was evaluated in 100 mL sterile 10 mg/L Hg2+-contaminated potato dextrose broth media in 250 mL Erlenmeyer flasks inoculated with 108spore/mL fungal spore suspension and incubation at 30℃ for 7 days. The mercury(Ⅱ) utilization was observed for flasks shaken in a 130 r/min orbital shaker(shaken) and nonshaken flasks(static) treatments. Flasks containing contaminated media with no fungal spores were also provided as control. All treatments were done in triplicate. The strain was able to remove 97.50%and 98.73% mercury from shaken and static systems respectively. A. flavus strain KRP1 seems to have potential use in bioremediation of aqueous substrates containing mercury(Ⅱ) through a biosorption mechanism.     

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.     

Evaluation of an electrolysis apparatus for inactivating antineoplastics in clinical wastewater

We recently reported a system for inactivating antineoplastics in which sodium hypochlorite is supplied by the electrolysis of sodium chloride solution. In this study, we designed an electrolysis apparatus for inactivating the cytotoxicity of antineoplastics in clinical wastewater using the system. The apparatus consists of an electrolysis cell with platinum-iridium electrodes, a pool tank, a circulating system for wastewater, a safety system for explosive gas and overflow, and an exhaust duct. The free chlorine concentration increased linearly up to 6500 mg l(-1), and pH also increased to 9.0-10.0 within 2h, when 0.9% sodium chloride solution was electrolyzed. We examined its efficacy with model and clinical wastewaters. The reciprocal of dilution factor for disappearance of cytotoxicity using Molt-4 cells was compared before and after electrolysis. In the model wastewater, that was 9.10 x 10(4) before electrolysis, and 3.56 x 10(2) after 2h of electrolysis. In the clinical wastewater (n=26), that was 6.90 x 10(3)-1.02 x 10(6) before electrolysis, and 1.08 x 10(2)-1.45 x 10(4) after 2h of electrolysis. Poisonous and explosive gases released by the electrolysis were measured; however, they were found to be negligible in terms of safety. The environmental load was evaluated by carbon dioxide generation as an index and it was found that the carbon dioxide generated by the electrolysis method was 1/70 lower than that by the dilution method with tap water. Moreover, the cost of the electrolysis method was 1/170 lower than that of the dilution method. This method was found to be both effective and economically valuable.     

Experimental testing of an annular denuder and filter system to measure gas–particle partitioning of semivolatile bifunctional carbonyls in the atmosphere

An annular denuder and filter-pack system was tested in combination with the use of the in-tube and on-fiber O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA)-derivatization technique to simultaneously sample and measure gaseous and particulate concentrations of semivolatile bifunctional carbonyl compounds in the atmosphere. Ozone was denuded from the sampling air to avoid oxidation and PFBHA was used as the sorbent by coating the sampling denuders and impregnating the filters. The collection efficiency of the system was evaluated under different conditions in photochemical smog chamber experiments and in field samplings of urban and suburban atmospheres. The effects of concentration level, temperature, and humidity on the collection efficiency were assessed. The system showed average collection efficiencies in one denuder from 81% for pyruvic acid and 82% for glyoxylic acid to 87% for hydroxyacetone and dihydroxyacetone. The capacity of the filters to collect the gaseous fraction that cannot be collected in the denuders was also evaluated, and the system allows a correction for this artifact. The application of this method to chamber experiments and field samplings offers an easy-to-apply technique with good results that can be used to evaluate the partition mechanisms of these compounds in the atmosphere.     

Cyst formation of the noxious red tide flagellate Chattonella marina (Raphidophyceae) in culture

Cyst formation of the noxious red tide flagellate Chattonella marina (Raphidophyceae), cultured from a cyst in sediments of Suo-nada, Japan in 1986, was investigated by culture experiments. Nitrogen limitation was effective in inducing cyst formation. After incubation in N-limited medium at 25°C with 10000 lux on a 14 h light, 10 h dark photo-cycle, cultures were subjected to six different light intensities (0 10000 lux) in order to determine effects of light intensity on cyst formation. Cysts were formed under light intensities of 1000 lux or below, but not at 10000 lux. Cysts formed in culture displayed morphological characteristics quite similar to those natural cysts observed in sediments collected from the Inland Sea of Japan. Observations on nucleus, using diaminidinophenylindole (DAPI)-staining and epifluorescence microscopy, indicated that the majority of cysts formed in culture were uninucleate, a few were binucleate. Germination of cysts was observed under adequate conditions for germination (22°C, 3500 lux with a 14 h light, 10 h dark photo-cycle) even after storage at 11°C in the dark for more than 4 mo.     

Assessing the impacts of current and future concentrations of surface ozone on crop yield with meta-analysis

Meta-analysis was conducted to quantitatively assess the effects of rising ozone concentrations ([O₃]) on yield and yield components of major food crops: potato, barley, wheat, rice, bean and soybean in 406 experimental observations. Yield loss of the crops under current and future [O₃] was expressed relative to the yield under base [O₃] (≤26 ppb). With potato, current [O₃] (31–50 ppb) reduced the yield by 5.3%, and it reduced the yield of barley, wheat and rice by 8.9%, 9.7% and 17.5%, respectively. In bean and soybean, the yield losses were 19.0% and 7.7%, respectively. Compared with yield loss at current [O₃], future [O₃] (51–75 ppb) drove a further 10% loss in yield of soybean, wheat and rice, and 20% loss in bean. Mass of individual grain, seed, or tuber was often the major cause of the yield loss at current and future [O₃], whereas other yield components also contributed to the yield loss in some cases. No significant difference was found between the responses in crops grown in pots and those in the ground for any yield parameters. The ameliorating effect of elevated [CO₂] was significant in the yields of wheat and potato, and the individual grain weight in wheat exposed to future [O₃]. These findings confirm the rising [O₃] as a threat to food security for the growing global population in this century.