Can nuclear aquatic environmental DNA be a genetic marker for the accurate estimation of species abundance?

The Science of Nature - We present the first study that compares phenological variation in parasite load and inflammatory response in a lizard with asynchronous male and female gonadal cycles....     

Causes of decreased reference evapotranspiration and pan evaporation in the Jinghe River catchment, northern China

This study focused on the changes of reference evapotranspiration (ET₀) and pan evaporation (ET_pan) to study the impacts of climate change on the hydrological cycle in the Jinghe River catchment. Based on the Penman–Monteith equation, the ET₀ was calculated. The temporal trend and spatial distribution of ET₀ and E_pan measured with a 20-cm pan were examined at the 14 stations during 1957–2005. The effects of meteorological factors on the variation of ET₀ were determined by analyzing the trends in themselves with comparison between original climate and detrended climate scenarios and then their sensitivity to ET₀. Both the ET₀ and E_pan showed remarkable decreasing trends from 1957 to 2005 and their decreasing rate was 40.9 and 17.7 mm per 10 years, respectively. Trend analysis of meteorological factors exhibited that the reduction in ET₀ and ET_pan was principally caused by both significant decreases in wind speed and sunshine hours. Furthermore, the decreasing trend of ET₀ was mainly dominated by the significant decrease in wind speed with high sensitivity, to a less extent, by the decrease in net radiation. Although relative humidity is one of the most sensitive variables, its effect on ET₀ was negligible because of its temporal constancy. The contribution of wind speed reduction to decreased ET₀ has increased from 50 to 76.1%, but net radiation, by contrast, decreased from 50 to 23.9%.     

Formation of chloroform and carbon tetrachloride in foods treated with sodium hypochlorite

The formation of chloroform and carbon tetrachloride during the treatment of fresh vegetable homogenate with sodium hypochlorite was studied.When a n-hexane extract of the reaction mixture of fresh vegetables and sodium hypochlorite was analysed by gas chromatography, chloroform and carbon tetrachloride were detected, and many unidentified peaks were also observed. The formation conditions of chloroform and carbon tetrachloride were studied. The mechanism of chloroform formation may be different from that of carbon tetrachloride according to the study of pH on the formation of both compounds. The formation of chloroform is much greater than that of carbon tetrachoride.     

Venoms from six species of marine fish: lethal and hemolytic activities and their neutralization by commercial stonefish antivenom

A specimen of the stonefish Synanceja verrucosa was captured in Okinawa in March 1988. Live specimens of the scorpionfish Inimicus japonicus were purchased from the Tokyo Central Wholesale Market in November 1988 and those of four species of zebrafish Pterois lumulata, P. volitans, P. antennata and Dendrochirus zebra from an aquarium in December 1988. Crude venoms were extracted from dorsal spines of the six species. All venoms exhibited lethal activity against mice and hemolytic activity specific for rabbit erythrocytes. The lethal activity (or hemolytic activity) of each venom was very unstable to freezing, lyophilization and heating. Both lethal and hemolytic activities of S. verrucosa venom were remarkably neutralized by the commerical stonefish (Synanceja trachynis) antivenom. This antivenom was also effective, to some extent, in counteracting the other venom activities. The neutralizing capacities of the antivenom were calculated to be 7310 LD₅₀ ml^-1 for S. verrucosa venom and 1 220 to 2 990 LD₅₀ ml^-1 for the other venoms. Results of neutralization tests suggest that venoms from the six species were comparable in terms of antigenecity.     

土壤和沉积物中痕量元素的ICP质谱法测定

人们对环境中污染物 (特别是重金属 )的“安全”水平的关注与日俱增 ,要分析的元素更多 ,浓度更低 ,从而暴露出当前所用分析技术的局限性 ,需要进一步提高分析方法的灵敏度和可分析的元素数量 .尽管ＧＦＡＡＳ (石墨炉原子吸收光谱 )和ＩＣＰ ＯＥＳ (感耦等离子体发射光谱 )仍是环境元素分析中最常用的技术 ,但ＩＣＰ ＭＳ (等离子体质谱 )是具有更高灵敏度的分析技术 ,不久肯定会被普遍接受 .ＨＰ 4 50 0台式ＩＣＰ质谱仪具有实际惯常分析应用所必需的可靠性和易于操作 ,可进行亚ｎｇ·ｍｌ- 1级 (ｐｐｂ)浓度水平的多元素快速分析 .本篇…     

Estimation of 1999-2004 dietary daily intake of PCDDs, PCDFs and dioxin-like PCBs by a total diet study in metropolitan Tokyo, Japan

A study of the dietary intake of dioxins, consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) through foods retailed in the metropolitan Tokyo area from 1999 to 2004 was carried out by the total diet-market basket method on the basis of food classification (14 groups) and the data on food consumption in the Tokyo region obtained from the Japan Nutrition Survey. The daily intake of dioxins per kg of body weight for a 50 kg average adult body was 2.18 pg TEQ/kg/day in 1999, 1.87 pg TEQ/kg/day in 2000, 1.25 pg TEQ/kg/day in 2001, 1.60 pg TEQ/kg/day in 2002 and 2003 and 1.55 pg TEQ/kg/day in 2004, respectively. These amounts were less than the tolerable daily intake (TDI) of 4 pg TEQ/kg/day for dioxins established in Japan. The dioxins taken daily through fish and shellfish (group 10) accounted for more than 50% of sum WHO-TEQs. In addition, more than 90% of the daily intake of dioxins was taken through fish and shellfish (group 10), meat and eggs (group 11), milk and dairy products (group 12). Also, this study clearly showed that the ratio of dioxin-like PCBs in the daily intake of dioxins was increasing yearly because the reduction rate of dioxin-like PCBs was lower than that of PCDDs and PCDFs in foods.     

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Abstract: Since 1979 the gold rush in the Brazilian Amazon has caused serious environmental damage to one of the most complex ecosystems on Earth. Mainly due to the toxicity of mercury to humans, this problem has received wide public attention and prompted many studies. Although these studies have involved sampling of fish, the negative effect of mercury contamination to fish themselves and other wildlife has been largely ignored. To assess the present level of mercury contamination of fish, and its implication for fish and other animals, we collected and examined data on mercury concentration in fish of the Brazilian Amazon, especially for the Tapajós basin, between 1991 and 1996. We conclude that omnivores and piscivores that live nearer to gold mining areas in the Tapajós basin are already at high risk of mercury toxification, especially reproductive failure. Mercury concentrations in these fish are also high enough to have detrimental effects on animals at higher trophic levels. The same conclusion applies to other mercury-contaminated areas in the Brazilian Amazon. Because most Amazonian rivers or their tributaries have favorable conditions for mercury contamination, we can expect the problem to persist in the Amazon for a long time, and the consequences are likely to become more significant in the future. These conclusions have important implications for all tropical rainforests where gold mining operations have caused extensive mercury pollution.     

Determination of PCDD/Fs and dioxin-like PCBs in fish oils for feed ingredients by congener-specific chemical analysis and CALUX bioassay

The present research was intended to determine the suitability of the CALUX assay as a screening method for dioxins in fish oil used as a feed ingredient in Japan. Alteration of TEQ in fish oil according to newly proposed toxic equivalency factors (TEF) is also discussed. In the analysis, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in 41 fish oil samples were determined by using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) and CALUX bioassay. The mean TEQ values derived from 1998 WHO-TEF of PCDD/Fs and DL-PCBs were 2.6 and 9.9 pg g(-1) (ww), respectively. The levels of TEQ derived from the recently re-evaluated 2005 WHO-TEF were slightly lower than those of the former in both groups. Notably, the contribution of mono-ortho DL-PCBs to total 2005 WHO-TEQ was considerably decreased compared to the case of 1998 WHO-TEQ, resulting from the reduction in its TEF values, while the non-ortho DL-PCBs contribution was increased. The mean TEQ determined by CALUX assay for PCDD/Fs was approximately three times higher, whereas DL-PCBs was approximately two times lower than WHO-TEQ determined by HRGC/HRMS; the sum of PCDD/Fs and DL-PCBs was very similar by both methods. The correlation coefficients of TEQ between the CALUX assay and HRGC/HRMS analysis were 0.84, 0.89, and 0.90 for PCDD/Fs, DL-PCBs, and the sum, respectively. These results suggest that the CALUX assay is a very useful method for the screening of dioxin-related compounds in fish oils.     

Accumulation of polychlorinated naphthalenes in domestic animal related samples

Concentrations of polychlorinated naphthalene (PCN) congeners were measured in domestic animal related samples such as feed ingredients, mixed feed and animal fat. Mean concentrations of total PCNs in feed ingredients ranged from 500 to 1500 pg g(-1) lipid wt with a high concentration found in fish meal. Total PCN concentrations were similar among mixed feeds, which ranged from 98 to 110 pg g(-1) lipid wt. The total PCN concentration in chickens was more than twice the amount in pigs. Tetra-CNs were the predominant homologues in all samples. Biomagnification of higher chlorinated PCN congeners, especially penta- and hexa-CNs, was a few fold greater in chickens compared to pigs. The estimated concentrations of 2,3,7,8-tetrachloro dibenzo-p-dioxin equivalents (TEQs) of some selected PCNs in feed ingredients, mixed feeds, chickens and pigs were 0.008 to 0.063, 0.001 to 0.002, 0.033 and 0.011 pg g(-1) lipid wt, respectively. Based on predicted luciferase inducing potency for each PCN congener, the estimated PCN-TEQs in feed ingredients and animal fat were similar to those that were estimated from selected PCNs.