The potential of in-situ monitoring of cytotoxic effects of chromium through root-tip assay was studied in a sugarcane cultivar CoLk 8102 (Saccharum spp. hybrid). Sugarcane setts supplied with graded concentrations of chromium (VI), exhibited a reduction of 85.92 and 95.10 % in mean root length at 40 and 80 ppm Cr dosages along with 61.25 and 82.50% reduction in mean root number/node respectively. Mitotic index of root tip cells of treated setts declined and the frequency of aberrant mitotic phases increased pari passu to the increasing chromium concentration. To compare and quantify the effect of graded chromium dosages on frequency of chromosome aberrations vis-à-vis inhibition of mitotic activity, a 'Decretion factor' (D.F.) has been used for the first time. The value of DF increased with the increase in the chromium dosages. The increase in chromosome aberration frequency was low at low chromium dosages (1 or 2 ppm), but the high Cr dosages (40 and 80 ppm), induced sharp reduction in mitotic efficiency of root system along with anomalies in the process of cell division and induced chromosome aberrations in sugarcane root meristem, which in turn affected the over all plant growth. 相似文献
Extensive production and use of organophosphate pesticide in agriculture, has risen concerned about its ecotoxicity and risk assessment of insecticides, which are more important. Therefore, the present investigation was aimed to study the induction of oxidative stress and DNA damage by organophosphate insecticide profenofos (PFF) in freshwater snail Lymnea luteola (L. luteola). The median lethal value (96 h LC50) of PFF was estimated as 1.26 mg/L for L. luteola in a semi-static system and on the basis of LC50 value three concentrations viz., 0.126 (1/10 of LC50, Sublethal I), 0.63 (1/2 of LC50, Sublethal II) and 0.84 mg/L (2/3 of LC50, Sublethal III) were determined. Snails were exposed to above-mentioned concentrations of PFF along with solvent control (acetone) and negative control for 96 h. The haemolymph was collected at 24 and 96 h of after treatment. In heamolymph of PFF exposed snail, lipid peroxide, glutathione reduced glutathione S transferase and superoxide dismutase activities at the tested concentrations significantly differ from those in the control. The genotoxicity induced in hemocytes of treated snails was measured by alkaline single cell gel electrophoresis assay. The data of this experiment demonstrated significantly enhancement of oxidative stress and DNA damage in the treated snails as compared to controls. Also, we observed statistically significant correlations of ROS with DNA damage (% tail DNA) (R2 = 0.9708) for 24 h and DNA damage (R2 = 0.9665) for 96 h.
Results of the current experiment can be useful in risk evaluation of PFF among aquatic organisms. The study confirmed the use of comet assay for in vivo laboratory experiments using freshwater snail for selecting the toxic potential of industrial chemicals and environmental contaminants.
Secondary pest outbreaks occur when the use of a pesticide to reduce densities of an unwanted target pest species triggers subsequent outbreaks of other pest species. Although secondary pest outbreaks are thought to be familiar in agriculture, their rigorous documentation is made difficult by the challenges of performing randomized experiments at suitable scales. Here, we quantify the frequency and monetary cost of secondary pest outbreaks elicited by early-season applications of broad-spectrum insecticides to control the plant bug Lygus spp. (primarily L. hesperus) in cotton grown in the San Joaquin Valley, California, USA. We do so by analyzing pest-control management practices for 969 cotton fields spanning nine years and 11 private ranches. Our analysis uses statistical methods to draw formal causal inferences from nonexperimental data that have become popular in public health and economics, but that are not yet widely known in ecology or agriculture. We find that, in fields that received an early-season broad-spectrum insecticide treatment for Lygus, 20.2% +/- 4.4% (mean +/- SE) of late-season pesticide costs were attributable to secondary pest outbreaks elicited by the early-season insecticide application for Lygus. In 2010 U.S. dollars, this equates to an additional $6.00 +/- $1.30 (mean +/- SE) per acre in management costs. To the extent that secondary pest outbreaks may be driven by eliminating pests' natural enemies, these figures place a lower bound on the monetary value of ecosystem services provided by native communities of arthropod predators and parasitoids in this agricultural system. 相似文献
The association between PON1 (serum paraoxonase) genotype and symptoms of pesticide toxicity was examined in a total of 268 farm workers in Andhra Pradesh, India. Approximately 140 of the farm workers who did not report at least two of the symptoms of chronic toxicity, such as abdominal pain, nausea, dizziness, headache, drowsiness, fatigue, tremors of fingers, numbness, or limb weakness were categorized as controls. The remaining 128 farmers showed 2 or more of the above symptoms. All the farm workers were genotyped for polymorphisms of PON1 gene at amino acid positions 55 (exon 3) and 192 (exon 6). A decrease in the percentage of high-activity genotypes at both L55M and Q192R was observed in the farm workers reporting symptoms of pesticide toxicity. When combined genotype distribution at both exons was analyzed, a marked increase in the percentage of low-activity genotypes LLQQ, LMQQ, MMQQ, and MMQR was also observed in symptomatic farmers compared to controls. Age, working years, smoking, duration of exposure, and alcoholism were not statistically significant when compared to symptoms of chronic toxicity. Our findings suggest that L55M and Q192R gene polymorphisms influence the variable susceptibility of farmers to pesticide; and thus may be considered a useful biomarker of genetic susceptibility in assessing an individual's risk of pesticide exposures. 相似文献
Exploration of heavy metals and organic pollutants, their leaching capacity along with health and environmental risks in contaminated industrial construction and demolition waste (ICDW) within a pesticide manufacturing plant were investigated. A maximum content of 90.8 mg?kg–1 Cd was found present in the wastes, which might originate from phosphorus rocks and industrial sulfuric acid used in pesticide production processes. An average concentration of 979.8 mg?kg–1 dichlorovos and other 11 organophosphorus pesticide were also detected. Relatively high leaching rates of around 4.14‰were obtained from laboratory simulated ICDW using both glacial acetic acid-sodium hydroxide and deionized water. Pesticide pollutants had the strongest tendency to retaining on dry bricks (leaching rate 1.68‰) compared to mortar-coatings, etc. due to their different physical characteristics and octanol-water partioning coefficient. Mobility of pesticide from on-site ICDW by water was spatially correlated to waste types, process sections and human activities, with a flux of leaching rate between 5.9‰ to 27.4%. Risk-based corrective action (RBCA) model was used to simulate the risk of contaminated ICDW debris randomly scattered. Oral and dermal ingestion amount by local workers was 9.8 × 10–3 and 1.9 × 10–2 mg?(kg?d)–1, respectively. Potential leaching risk to aquatic systems exceeded the limit for nearly 75% waste. Environmental and health risk exceedance was found in most ICDW, while the risk value of the most severely contaminated brick waste was 660 times beyond critical level. Implications for waste management involving construction and deconstruction work, waste transferring and regulation supplying were also provided.
Three different karyomorphs with 2n=46, 2n=44 and 2n=42 for Capros aper (L., 1758) (Zeiformes) collected from the Gulf of Lion, near Banyuls-sur-Mer, France, in July 1990 were determined. Karyomorphs were characterized by the same arm number [Fundamental number (FN)=50], suggesting that chromosome variations are due to Robertsonian fusions. In somatic metaphase spreads stained with silver nitrate, nucleolus organizer regions (NORs) consistently occupied a terminal position on the short arms of two small submetacentric chromosomes. Ca. 30% of silver-stained metaphases in each specimen showed NOR chromosomes associated in pairs by their nucleolus organizer regions. 相似文献
Summary 1. Echolocation and foraging behavior of the horseshoe bats Rhinolophus ferrumequinum and R. hipposideros feeding under natural conditions are described. 2. The calls of both species consisted predominantly of a long CF segment, often initiated and terminated by brief FM sweeps of substantial bandwidth. 3. R. hipposideros typically flew close to vegetation, and fed by aerial hawking, gleaning and by pouncing on prey close to the ground. R. hipposideros called with a CF segment close to 112 kHz which is the second harmonic of the vocalization; its calls included low intensity primary harmonics, and had prominent initial and terminal FM sweeps of considerable bandwidth. When searching for prey on the wing it had longer interpulse intervals than R. ferrumequinum, but emitted shorter pulses at a higher repetition rate; overall it had a similar duty cycle to R. ferrumequinum. 4. R. ferrumequinum, calling with a CF segment close to 83 kHz, also used harmonics other than the dominant secondary in its calls, and modified its echolocation according to ecological conditions. This species showed certain parallels with R. rouxi of Asia. It was observed feeding by aerial hawking and by flycatching. When scanning for prey from a perch (perch hunting), calls were of shorter duration, and interpulse intervals were on average longer, than when bats were flying. Mean duty cycle was longer in flight, and the bandwidths and frequency sweep rates of the FM segments in the calls increased in comparison with perched bats. 5. FM information may facilitate determination of target range and the location and nature of obstacles; it may also be involved in the interpretation of echoes and the detection of moving targets among clutter. The rising FM sweep initiating the call in both species when flying (and to a lesser extent perch hunting) in the wild must have a significant adaptive role, and should be considered an essential component of the call; rhinolophids should be termed FM/CF/FM bats.Abbreviations CF
constant frequency
- FM
frequency modulated
- FM1
initial rising frequency sweep
- FM2
terminal falling frequency sweep
- PRR
pulse repetition rate
- SD
standard deviation
- SNR
signal-to-noise ratio 相似文献
The in vitro study was carried out to examine the toxicity of four commercially used pesticides (phorate, mancozeb, chlorpyrifos, and endosulfan) at the recommended dose (1X) and higher field doses (1.5X, 2X, 2.5X, and 3X) on plant growth-promoting activities of Burkholderia sp. strain L2, isolated from pesticide-treated rhizosphere of Lycopersicon esculentum. At the recommended dose, level of toxicity of all the pesticides to phosphate solubilization activity and indole-3-acetic acid (IAA) production was less detrimental as compared to exceeding doses. At maximum dose rate of each pesticide, the percentage decrease in phosphate solubilization and IAA production over control was found in order of chlorpyrifos < mancozeb < endosulfan < phorate. Present study proves that Burkholderia sp. strain L2 could be used as a potential microbial inoculant in the agricultural soil having persistent pesticide residues. 相似文献
A karyotypic analysis was carried out in turbot (Scophthalmus maximus) using conventional banding techniques, fluorochromes and restriction endonucleasebanding. The standard karyotype of turbot is 2n=44 chromosomes, with 48 chromosome arms. Nucleolar organizer regions, which were localized in the short arm of Chromosome Pair No. 3, showed C-and chromomycin A3-positive staining. C-bands were mainly located at the centromeres, but were also present in some interstitial and telomeric locations. No differences were revealed among constitutive heterochromatin bands after treatment of fixed chromosomes with fluorochrome staining and restriction endonucleases. Digestion with DdeI restriction enzyme produced a pattern of interstitial banding which suggested some degree of differentiation along the chromosome arms in turbot. Neither variation in chromosome number of arm number nor polymorphism in nucleolar organizer regions was revealed in the turbot analyzed. 相似文献