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Khandavilli Sharada Bharathi P. Salimath H. Shekar Shetty N. Gopalakrishna K. Karanth 《Pest management science》1992,35(4):315-319
In rice seedlings, the organochlorine insecticide hexachlorocyclohexane (HCH) and its four major isomers—α,β, γ, and δ—have been shown to elicit their phytotoxic action by interacting with indol-3-ylacetic acid (IAA)-regulated growth and Ca2+-ATPase activity. When rice seedlings were grown in the presence of 0.34 mM HCH, seedling vigour was reduced to 33% of the control. A similar effect was observed when seedlings were grown in the presence of the γ and δ isomers, but not with the α and δ isomers of HCH. This reduced vigour could be restored by treating the seedlings with 100 nM IAA, suggesting that HCH and its isomers (γ and δ) limit either IAA synthesis or action or both. In a microsomal fraction from rice seedlings grown in the presence of either HCH or its isomers, the calmodulin-regulated Ca2+-ATPase activity was inhibited as follows: technical HCH = 46%, α isomer = 80%, β isomer = 72%, γ isomer = 65% and δ isomer = 62% of the control value, respectively. TLC analysis suggested that the various isomers of HCH are metabolised by the plant, except for the δ isotner, which accumulated. This isomer, along with the degraded products of other isomers, may be responsible for the phytotoxic action of HCH. 相似文献
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Impact of Endocrine‐Disrupting Chemicals on Reproductive Function in Zebrafish (Danio rerio) 
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下载免费PDF全文 The prevalence of endocrine‐disrupting chemicals (EDCs) in the aquatic environment has been associated with the wide detection of alterations in the development and physiology of vertebrates. Zebrafish, as a model species, has been extensively used in toxicological research. In this review, we focus on recent published evidence of the harmful effects of EDCs on reproductive function in zebrafish, including skewed sex ratio, immature gonads, diminished sexual behaviour, decreased sperm count, reduced spawning and fertilization. These impairments mostly result from disruption to sex‐steroid hormones induced by endocrine disruptors. We also discuss other effects of exposure to EDCs. In EDC exposure research, despite incomplete assessments of altered gonad histopathology and sexual behaviour, these present potential effective biomarkers or pathways for evaluating the reproductive function in zebrafish on EDC exposure. To date, the pernicious effects of some EDCs on the reproductive performance in laboratory zebrafish are well understood; however, similar alterations remain for further determination in wild‐type fish and more kinds of EDCs. More studies should be performed under established scientific regulatory criteria to investigate the impact of EDCs on reproduction in zebrafish. Moreover, further research is required to explain the definite mechanism of sexual differentiation, which helps in understanding the shift of sexual phenotype with EDC exposure. 相似文献
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RD Jolly JJ Hopwood NR Marshall KS Jenkins DJ Thompson KE Dittmer 《New Zealand veterinary journal》2013,61(3):183-188
Abstract AIM: To investigate and characterise an inborn error of metabolism in a dog with skeletal and ocular abnormalities. METHODS: A 2.5-year-old small male Miniature Poodle-like dog was presented with gross joint laxity and bilateral corneal opacities. Clinical examination was augmented by routine haematology, serum chemistry, radiographs, pathology, enzymology and molecular genetic studies. Euthanasia was requested when the dog was 3 years of age because of progressively decreasing quality of life. RESULTS: Radiology revealed generalised epiphyseal dysplasia, malformed vertebral bodies, luxation/subluxation of appendicular and lumbosacral joints with hypoplasia of the odontoid process and hyoid apparatus. These clinical and radiographic findings, together with a positive urinary Berry spot test for mucopolysaccharides, and metachromatic granules in leucocytes, were indicative of a mucopolysaccharidosis (MPS), a lysosomal storage disease. Histological lesions included vacuolation of stromal cells of the cornea, fibroblasts, chondrocytes, macrophages and renal cells. The brain was essentially normal except for moderate secondary Wallerian-type degeneration in motor and sensory tracts of the hind brain. Dermatan sulphate-uria was present and enzymology revealed negligible activity of N-acetylgalactosamine-4-sulphatase, also known as arylsulphatase B, in cultured fibroblasts and liver tissue. A novel homozygous 22 base pair (bp) deletion in exon 1 of this enzyme's gene was identified (c.103_124del), which caused aframe-shift and subsequent premature stop codon. The “Wisdom pure breed-mixed breed” test reported the dog as a cross between a Miniature and Toy Poodle. CONCLUSIONS: The clinicopathological features are similar to those of MPS type VI as previously described in dogs, cats and other species, and this clinical diagnosis was confirmed by enzymology and molecular genetic studies. This is an autosomal recessively inherited lysosomal storage disease. CLINICAL RELEVANCE: The prevalence of MPS VI in Miniature or Toy Poodles in New Zealand and elsewhere is currently unknown. Due to the congenital nature of the disorder, malformed pups may be subject to euthanasia without investigation and the potential genetic problem in the breed may not be fully recognised. The establishment of a molecular genetic test now permits screening for this mutation as a basis to an informed breeding policy. 相似文献
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Measurements of the equation of state of deuterium at the fluid insulator-metal transition 总被引：1，自引：0，他引：1
GW Collins Da Silva LB P Celliers DM Gold ME Foord RJ Wallace A Ng SV Weber KS Budil R Cauble 《Science (New York, N.Y.)》1998,281(5380):1178-1181
A high-intensity laser was used to shock-compress liquid deuterium to pressures from 22 to 340 gigapascals. In this regime deuterium is predicted to transform from an insulating molecular fluid to an atomic metallic fluid. Shock densities and pressures, determined by radiography, revealed an increase in compressibility near 100 gigapascals indicative of such a transition. Velocity interferometry measurements, obtained by reflecting a laser probe directly off the shock front in flight, demonstrated that deuterium shocked above 55 gigapascals has an electrical conductivity characteristic of a liquid metal and independently confirmed the radiography. 相似文献
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KS Johnson JH Thywissen NH Dekker KK Berggren AP Chu R Younkin M Prentiss 《Science (New York, N.Y.)》1998,280(5369):1583-1586
The spatially dependent de-excitation of a beam of metastable argon atoms, traveling through an optical standing wave, produced a periodic array of localized metastable atoms with position and momentum spreads approaching the limit stated by the Heisenberg uncertainty principle. Silicon and silicon dioxide substrates placed in the path of the atom beam were patterned by the metastable atoms. The de-excitation of metastable atoms upon collision with the surface promoted the deposition of a carbonaceous film from a vapor-phase hydrocarbon precursor. The resulting patterns were imaged both directly and after chemical etching. Thus, quantum-mechanical steady-state atom distributions can be used for sub-0.1-micrometer lithography. 相似文献
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N.G.K. Karanth S.G. Bhat C.S. Vaidyanathan V.N. Vasantharajan 《Pesticide biochemistry and physiology》1976,6(1):20-29
p-Dimethylaminobenzenediazo sodium sulfonate (DABDS)-reductase catalyzing the conversion of DABDS to N,N-dimethyl-p-phenylenediamine was purified to homogeneity from the cell-free extracts of Pseudomonas fragi Bk9, crystallized, and its properties studied. The homogeneity of the enzyme was ascertained by gel electrophoresis and immunodiffusion studies. The molecular weight of the enzyme as determined by the gel filtration method was found to be approximately 87,000. The enzyme was optimally active at pH 7 and 45°C, with an activation energy of 2.5 kcal/mol. NADH, NADPH, and GSH could not function as cofactors, while the enzyme required dithiothreitol as an electron donor. From the Lineweaver-Burk plots, the Km values were calculated to be 0.90 and 3.53 mM for DABDS and dithiothreitol, respectively. The enzyme did not show any requirement for metal ions and was inhibited to varying degrees by different sulfhydryl reagents. 相似文献
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Hunting is one of the greatest conservation challenges facing tropical wildlife. Wildlife in Indian tropical forests are vulnerable to hunting, although data on hunting impacts from the region are limited. We use a meta-analysis of 143 hunting studies from India to identify the species and geographic regions most at risk, and to assess their legal protection. We found evidence of hunting in 114 mammal species, with larger-bodied mammals being particularly vulnerable. Although 75% of all studies focused on mammals, few actually quantified hunting impacts. Further, among studies of all terrestrial vertebrates where hunting was mentioned, only 6% focused exclusively on hunting. With further research, we expect that the suite of species known to be exploited by hunters will increase. We conclude that the Eastern Himalaya and Indo-Myanmar biodiversity-hotspot complex is particularly vulnerable to hunting. Quantitative studies of hunting impacts are urgently needed across India, especially in this biodiversity-hotspot complex. 相似文献
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The effect of the fungicide Dexon (p-dimethylaminobenzenediazo sodium sulfonate) on CO2 production from soil amended or not with organic matter, was studied for 60 days. Dexon was found to retard the breakdown of glucose and paddy straw added to soil. Inhibition of CO2 production occurred during the early stages of glucose decomposition and in the case of straw throughout the period of study. Dehydrogenase activity in the soil was also found to be reduced by this fungicide. Total organic carbon content increased when straw was added to soil in the presence of Dexon. On the other hand, addition of Dexon alone to soil caused a decrease in the amount of organic carbon. Its effect on nitrogen content of the soil was marginal. Dexon had almost completely disappeared from the soil by 60 days. 相似文献