Use of the alkaline comet assay for monitoring genotoxic effects of arsenic in human populations.

The alkaline comet assay has been widely used to determine genotoxicity in human populations exposed to arsenic. The sample sizes of earlier studies were usually small, and inconsistent results were found. Meta-analyses can merge the results of multiple studies of the same type and increase the credibility of the conclusion by increasing the sample size. Thus, to investigate the monitoring effect of alkaline comet assay on genotoxicity for arsenic exposed population, meta-analyses were performed. Thirteen studies were found to meet the inclusion criteria and were included in this study; of them, twelve articles were of medium quality (15-20 points), only one study was of high quality (21-27 points). Meta-analyses showed that the overall estimates of Mean Ratio (MR, defined as the mean value of the response in the exposed group divided by that in the reference group) were 2.81(95 % confidence interval (CI) 1.93-4.10); 2.37(95 % CI, 1.73-3.26), and 1.69(95 %CI, 1.29-2.20) for comet tail length, % tail DNA, and tail moment, respectively. This shows that the level of DNA damage in arsenic exposed population is significantly higher than that in control populations. A meta-analysis of the correlation coefficients showed that the overall estimate was 0.52 (95 %CI, 0.48∼0.56, P<0.05) with all correlation coefficients included, but it changed to 0.24 (95 %CI, 0.17∼0.28, P<0.05) when two abnormal correlation coefficients were excluded, suggesting there was a positive correlation between arsenic load in vivo and DNA damage, but the overall estimate value of coefficients was unstable. Therefore, we conclude that the alkaline comet assay can be used as an effective genotoxic biomonitoring tool for arsenic-exposed populations. However, more and higher-quality studies are still needed to verify its actual application value.

Regulating effect of spraying stage of ethephon on the formation of source-sink in peanut.

To solve the problem of uncoordinated source-sink relationship that limits the increase of peanut yield, we investigated the regulating effects of ethephon on the formation of source-sink in cultivar Shanhua 9 by spraying at 10, 20, and 30 d after anthesis in a field experiment. The results showed that spraying ethephon at 10 d and 20 d after anthesis significantly reduced the number of flowers, pegs and young pods, but increased the number of immature pods and mature pods. Spraying at 30 d after anthesis did not affect the number of flowers, pegs and young pods. Spraying ethephon could improve the leaf area per plant. Spraying at 10 d after anthesis achieved the highest leaf area per plant and the increment amplitude decreased with the delay of spraying stage. Spraying ethephon at 10 d and 20 d after anthesis significantly improved the photosynthetic performance of peanut, whereas spraying at 30 days after anthesis increased the photosynthesis only in the short-term and had no effect at late growth period. In terms of the comprehensive characters of source and sink, spraying ethephon at 20 d after anthesis achieved the most harmonious source-sink relationship, which could promote the transport of photosynthate to pods and increase the economic pods ratio, pod fullness, and the yield. Therefore, spraying ethephon is an effective practice to solve the problems of "more flowers but less pegs" and "more pods but less kernels" in peanut. The optimum spraying stage of ethephon to regulate flowering should be at 20 d after anthesis.

[Effect of row spacing on physiological characteristics and yield of intercropped peanut with wheat.] / å°éº¦è¡Œè·é ç½®å¯¹å¥—ç§èŠ±ç”Ÿç”Ÿç†ç‰¹æ€§å’Œäº§é‡çš„å½±å“.

Using two peanut varieties Shanhua108 (early-maturing variety) and 780-15 (late maturing variety), a field experiment was conducted to investigate the influences of row-spacing of wheat (25 cm, 30 cm, 40 cm+20 cm) and two peanut cropping patterns (intercropped peanut with wheat, summer-sowing peanut) on yield components, photosynthetic characteristics, antioxidant system, and dry matter accumulation and transportation. The results showed that wide spacing form of wheat and wide-narrow row planting pattern increased the pod yield, kernel yield, leaf area index, total dry matter accumulation and photosynthetic capacity, as well as SOD, POD and CAT activities, but decreased the MDA content. There are no obvious differences of wheat yield between the two row-spacing. Intercropping system increased peanut yield compared with summer-sowing peanut, which were much higher for wide-narrow row planting pattern than row spacing of 25 cm or 30 cm. The wide-narrow row planting pattern increased the pod yield and kernel yield by 6.3%, 13.3% and 7.7%, 16.5% for Shanhua108 and 780-15 than those of row spacing of 30 cm, respectively. Wide-narrow row planting could enlarge photosynthetic area, improve the net photosynthetic rate, and increase total dry matter accumulation. Meanwhile, it could alleviate the contradictionbetween the plant individual and group, delay the senescence, and increase peanut yield.

[Responses of winter wheat tillers at different positions to low temperature stress at stem elongation stage and their freezing resistance evaluation].

Taking two winter wheat cultivars Ji' nan 17 and Shannong 8355 as test materials, this paper measured the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and the malondialdehyde (MDA) and soluble protein contents in the functional leaves and sheaths of the tillers at different positions at stem elongation stage under low temperature stress, and then, the freezing resistance of the tillers was comprehensively evaluated by the methods of principal component analysis and cluster analysis. The results showed that under low temperature stress, the SOD, POD, and CAT activities in the functional leaves and sheaths of each tiller at stem elongation stage increased, but the MDA and soluble protein contents increased or decreased to some extent. By using principal component analysis and cluster analysis, the tillers of each cultivar were grouped into three kinds of freezing resistance type. For Ji' nan 17, the main stem, tiller I, and tiller II belonged to high freezing resistance type, the tiller III, tiller IV, and tiller I p belonged to medium freezing resistance type, and the tiller II p belonged to low freezing resistance type. For Shannong 8355, the main stem, tiller I, tiller II, and tiller III belonged to high freezing resistance type, the tiller IV and tiller I p belonged to medium freezing resistance type, and the tiller II p belonged to low freezing resistance type. It was concluded that the freezing resistance of the winter wheat tillers at different positions at stem elongation stage differed, with the lower position tillers being more resistant than the higher position tillers.

[Effects of methamidophos and 17beta-estradiol on the dynamics of experimental population of freshwater rotifer Brachionus calyciflorus].

The study on the dynamics of experimental population of freshwater rotifer Brachionus calyciflorus under exposure of different concentrations of methamidophos (0.01, 0.1, 1.0, 10.0, 100.0, 1000.0 and 10000.0 microg x L(-1)) and 17beta-estradiol (0.001, 0.01, 0.1, 1.0, 10.0, 100.0 and 1000.0 microg x L(-1)) showed that both methamidophos and 17beta-estradiol had significant effects on the mean growth rate of the population, but less affected the mean fertilization rate of mictic females. Methamidophos affected the mean ratio of ovigerous to non-ovigerous females and the mean mictic rate significantly but had less effect on the total resting egg production, while 17beta-estradiol was in adverse. Compared with the controls, both 10.0-10000.0 microg x L(-1) of methamidophos and 100.0 microg x L(-1) of 17beta-estradiol increased the mean population growth rate significantly. 0.1-10000.0 and 10.0 microg x L(-1) of methamidophos decreased significantly the average ratio of ovigerous to non-ovigerous females and the average mictic rate, respectively, and 1000.0 microg x L(-1) of 17beta-estradiol decreased the total resting egg production significantly. Within the range of test concentrations of methamidophos, the relationship between the mean population growth rate (Y, d(-1) and the concentration (X, microg x L(-1) of methamidophos could be described as Y = -2 x 10(-8) X2 + 0.002X + 0.374. The population growth rate could be used to assess the effects of methamidophos on the population dynamics of the rotifer.

An emission inventory of marine vessels in Shanghai in 2003.

We developed an air pollutant emission inventory for marine vessels in the Shanghai Port in 2003. We estimated emissions under cruising and maneuvering conditions based on two categories of vessels: (1) vessels in the Outer Port, which enter the area following notification of the Shanghai Maritime Safety Administration, a division of the Ministry of Communications of P.R. China; and (2) vessels in internal waterways, which enter those waters following notification of the local Port Administration Centers. Vessels in the Outer Port consist of three subcategories: (1) international vessels that are engaged in foreign commerce; (2) domestic vessels traveling along the downstream portion of the Huangpu River; and (3) domestic vessels traveling along the coast. We also estimate emissions from vessels over 1000 DWT operating under hotelling conditions in the Outer Port. In 2003, the total number of calls was approximately 1.3 million, of which 57% is attributed to vessels in internal waterways and 43% to vessels in the Outer Port. Total marine emissions for NOx, SO2, PM, HC, and CO2 in 2003 are estimated to be 58,160, 51,180, 6960, 4560, and 3,012,800 tons, respectively. Emissions are allocated to 1 km x 1 km grid cells for the 129 km x 102 km Shanghai Port study domain.