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951.
Previous studies have reported that triclosan (TCS) could possess an androgenic activity. We aimed to investigate the effects of TCS on gonadal differentiation and development in the frog Pelophylax nigromaculatus, a sensitive amphibian species to androgenic chemicals. P. nigromaculatus tadpoles at stage 24 were exposed to TCS (3, 30, and 300 nmol/L) to stage 46 in a semi-static exposure system. At the end of exposure, gonadal morphology and histology, sex ratio and gonadal expression of sex-biased genes were examined in P. nigromaculatus. In each TCS treatment group, we found several individuals whose gonads exhibited morphological and/or histological abnormalities. Gonadal histological abnormalities were characterized by few oocytes and many somatic cells. Although the percentage of the individuals with abnormal gonads was low (7.8%) among all animals treated with TCS, statistical test revealed the sex ratios in the 3 and 300 nmol/L TCS treatment groups were significantly different from the solvent control. In the 30 nmol/L TCS treatment group, abnormal gonads were also observed, although the sex ratio was not changed compared with the solvent control, which was possibly due to the smaller sample size in this group. In all the TCS treatment groups, the sex ratios were not obviously male-biased, but the expression levels of some sex-biased genes were significantly altered by TCS. Altogether, our results suggest that TCS, even at environmentally relevant concentrations, could disrupt gonadal differentiation and development in P. nigromaculatus, but we are not sure whether the disrupting effects were associated with masculinization or feminization. 相似文献
952.
953.
In vivo activity of cholinesterase (ChE) in Daphnia magna was measured at di erent time points during 21-day exposure to triazophos
and chlorpyrifos ranging from 0.05 to 2.50 g/L and 0.01 to 2.00 g/L, respectively. For exposure to triazophos, ChE was induced up
to 176.5% at 1.5 g/L and day 10 when measured by acetylthiocholine (ATCh), whereas it was induced up to 174.2% at 0.5 g/L
and day 10 when measured by butyrylthiocholine (BTCh). For exposure to chlorpyrifos, ChE was induced up to 134.0% and 160.5%
when measured by ATCh and BTCh, respectively, with both maximal inductions detected at 0.1 g/L and day 8. Obvious induction
in terms of ChE activity was also detected in daphnia removed from exposures 24 hr after their birth and kept in a recovery culture
for 21 days. Results indicated that the enzyme displayed symptoms of hormesis, a characteristic featured by conversion from low-dose
stimulation to high-dose inhibition. In spite of that, no promotion in terms of reproduction rate and body size was detected at any tested
concentrations regardless of whether the daphnia were collected at end of the 21-day exposure or at end of a 21-day recovery culture.
This suggested that induction of ChE caused by anticholinesterases had nothing to do with the prosperity of the daphnia population. 相似文献
954.
A biological safety evaluation on reclaimed water reused as scenic water using a bioassay battery 总被引:1,自引:0,他引:1
An assessment method based on three toxicity tests (algae growth inhibition, daphnia immobilization and larval fish toxicity) was used to screen the biological safety of reclaimed water which was reused as sole replenishment for scenic water system in a park (SOF Park) in northern China. A total of 24 water samples were collected from six sites of water system in the SOF Park in four different seasons. The results indicated that: (1) the reclaimed water directly discharged from a reclamation treatment plant near the SOF Park as influent of park had relatively low biological safety (all samples were ranked as C or D); (2) the biological safety of reclaimed water was improved greatly with the ecological reclamation treatment processes composing of artificial wetland system and followed oxidation pond system; (3) the biological safety of reclaimed water in the main lake of SOF Park kept at a health status during different seasons (all samples were ranked as A); (4) there was some certain correlation (R2 = 0.5737) between the sum of toxicity scores and dissolved organic carbon for the studied water samples. It was concluded that the assessment method was reliable to screen the safety of reclaimed water reused as scenic water, and the reclaimed water with further ecological purification processes such as artificial wetland and oxidation pond system can be safely reused as scenic water in park. 相似文献
955.
956.
Tan K Radloff SE Li JJ Hepburn HR Yang MX Zhang LJ Neumann P 《Die Naturwissenschaften》2007,94(6):469-472
The vespine wasps, Vespa velutina, specialise in hawking honeybee foragers returning to their nests. We studied their behaviour in China using native Apis cerana and introduced A. mellifera colonies. When the wasps are hawking, A. cerana recruits threefold more guard bees to stave off predation than A. mellifera. The former also utilises wing shimmering as a visual pattern disruption mechanism, which is not shown by A. mellifera. A. cerana foragers halve the time of normal flight needed to dart into the nest entrance, while A. mellifera actually slows down in sashaying flight manoeuvres. V. velutina preferentially hawks A. mellifera foragers when both A. mellifera and A. cerana occur in the same apiary. The pace of wasp-hawking was highest in mid-summer but the frequency of hawking wasps was three
times higher at A. mellifera colonies than at the A. cerana colonies. The wasps were taking A. mellifera foragers at a frequency eightfold greater than A. cerana foragers. The final hawking success rates of the wasps were about three times higher for A. mellifera foragers than for A. cerana. The relative success of native A. cerana over European A. mellifera in thwarting predation by the wasp V. velutina is interpreted as the result of co-evolution between the Asian wasp and honeybee, respectively. 相似文献
957.
958.
惠州市农业土壤中邻苯二甲酸酯(PAEs)含量的分布特征 总被引:4,自引:0,他引:4
用气相色谱法(GC-FID)对地处珠三角地区的惠州市49个农业土壤样品中的16种PAEs化合物进行了测定。结果表明,PAEs的检出率高达100%,其中土壤中PAEs含量范围为183.48~2 037.56 ug/kg,平均600.42 ug/kg,以DnBP、BEHP和DEHP等为主。在3种主要利用类型土壤中,∑PAEs含量高低排序为菜地水田果园。与美国土壤PAEs控制标准相比,惠州土壤中的DnBP、DMP和DEP含量超标,其中DnBP的超标率达85.71%。总体上惠州市农业土壤已受到一定程度的PAEs污染,但同其它地区相比处于较低水平。 相似文献
959.
960.
广东佛山市某工业园内污水处理厂采用混凝/生物接触氧化工艺对牛仔服装洗水废水进行集中处理,进水水量30 000 m3/d,水质ρ(COD)=411 mg/L、ρ(BOD5)=147 mg/L、ρ(SS)=313 mg/L、色度为239倍、pH=7~9,出水相应指标分别为ρ(COD)=53 mg/L、ρ(BOD5)=16 mg/L、ρ(SS)=32 mg/L、色度为8倍、pH为7.5,达到广东省地方标准DB 44/26—2001《水污染物排放限制》第二时段中的一级标准。此工艺具有工程投资少、运行稳定、处理效果好、成本低等优点。 相似文献