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81.
82.
Quantitative analysis of organophosphorus pesticides in freshwater using an optimized firefly luciferase‐based coupled bioluminescent assay
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In this paper, a coupled bioluminescent assay, relying on the coupling of the enzymes acetylcholinesterase, S‐acetyl‐coenzyme A synthetase and firefly luciferase, for the detection and quantitation of organophosphorus pesticides, is presented. Using malathion as a model organophosphorus pesticide, the assay was optimized through statistical experimental design methodology, namely Plackett–Burman and central composite designs. The optimized method requires only 20 μL of sample. The linear range for the assay was 2.5–15 μM of malathion, with limits of detection and quantitation of 1.5 and 5.0 μM, respectively. This simple, fast and robust method allows samples to be analyzed at room temperature and without any pretreatment. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
83.
Snake venoms are cocktails comprising combinations of different proteins, peptides, enzymes and toxins. Snake toxins have
diverse characteristics having different molecular configuration, structure and mode of action. Many toxins derived from snake
venom have distinct pharmacological activities. Venom from Bungarus fasciatus (commonly known as banded krait) is a species of
elapid snake found on the South East Asia and Indian sub-continent, mainly contains neurotoxins. Beta bungartotoxin is the major
fraction of Bungarus venom and particularly act pre-synaptically by obstructing neurotransmitter release. This toxin in other
snake species functionally forms a heterodimer containing two different subunits (A and B). Dimerization of these two chains is a
pre-requisite for the proper functionality of this protein. However, B. fasciatus bungartotoxin contains only B chain and their
structural orientation in yet to be resolved. Therefore, it is of interest to describe the predicted structure model of the toxin for
functional insights. In this work we analyzed the neurotoxic nature, their alignments, secondary and three dimensional structures,
functions, active sites and stability with the help of different bioinformatical tools. A comprehensive analysis of the predicted model
provides approaching to the functional interpretation of its molecular action. 相似文献
84.
Chemotherapy often induces bone growth defects in pediatric cancer patients; yet the underlying cellular mechanisms remain unclear and currently no preventative treatments are available. Using an acute chemotherapy model in young rats with the commonly used antimetabolite methotrexate (MTX), this study investigated damaging effects of five once-daily MTX injections and potential protective effects of supplementary treatment with antidote folinic acid (FA) on cellular activities in the tibial growth plate, metaphysis, and bone marrow. MTX suppressed proliferation and induced apoptosis of chondrocytes, and reduced collagen-II expression and growth plate thickness. It reduced production of primary spongiosa bone, volume of secondary spongiosa bone, and proliferation of metaphyseal osteoblasts, preosteoblasts and bone marrow stromal cells, with the cellular activities being most severely damaged on day 9 and returning to or towards near normal levels by day 14. On the other hand, proliferation of marrow pericytes was increased early after MTX treatment and during repair. FA supplementation significantly suppressed chondrocyte apoptosis, preserved chondrocyte proliferation and expression of collagen-II, and attenuated damaging effects on production of calcified cartilage and primary bone. The supplementation also significantly reduced MTX effects on proliferation of metaphyseal osteoblastic cells and of bone marrow stromal cells, and enhanced pericyte proliferation. These observations suggest that FA supplementation effectively attenuates MTX damage on cellular activities in producing calcified cartilage and primary trabecular bone and on pools of osteoblastic cells and marrow stromal cells, and that it enhances proliferation of mesenchymal progenitor cells during bone/bone marrow recovery. 相似文献
85.
Claire SM Kwan Rafael P Vázquez-Manrique Sung Ly Kshamata Goyal Howard A Baylis 《BMC physiology》2008,8(1):11
Background
Ultradian rhythms, rhythms with a period of less than 24 hours, are a widespread and fundamental aspect of life. The mechanisms underlying the control of such rhythms remain only partially understood. Defecation in C. elegans is a very tightly controlled rhythmic process. Underlying the defecation motor programme is an oscillator which functions in the intestinal cells of the animal. This mechanism includes periodic calcium release and subsequent intercellular calcium waves which in turn regulate the muscle contractions that make up the defecation motor programme. Here we investigate the role of TRPM cation channels in this process. 相似文献86.
The aim of this review is to explore the idea that the glycosaminoglycan sugar heparan sulfate (HS), richly concentrated on the plasma membrane of all animal cells studied so far and a major component of extracellular matrices, is by virtue of its ability to modulate protein gradients and signal transduction, the master regulator of stem cell fate (and thus wound healing). Moreover, the interaction between HS and members of the TGF-beta superfamily is emerging as a central tenet for stem cells. The potential significance of this interaction is best understood by examining both how HS modulates ligand interactions and stability, and how it maintains protein gradients with varying degrees of specificity. Importantly, HS also regulates the activity of numerous antagonists, thus underscoring its importance as a primary regulator of stem cell fate decisions. 相似文献
87.
Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin
lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed
from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and
their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly
treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group
UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August
due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move
to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better
weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the
value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture
infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better
despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments
of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without
dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where
routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed. 相似文献
88.
The agricultural sector, and particularly the horticultural production, has a singular importance in agriculture, considering that it ranks second on agricultural products, nationally and worldwide. Fungal diseases are one of the major causes of vegetable loss during storage, reducing their nutritional value, quality and sale price. Vegetables are usually exposed to diverse treatments with chemical products before storage; as a result, fungal populations develop an increased resistance over time becoming more difficult to control. Because of this, research efforts toward finding more suitable chemicals to control fungal diseases are needed. Natural extracts may be an alternative solve this problem. In the present investigation the fungicidal activity of aqueous and ethanol extracts of Agave scabra was evaluated on the growth of Botrytis cinerea, Mucor sp., Aspergillus niger, Fusarium sp. and Penicillium sp., whose strains were isolated from potato and tomato. To assess their effects, the agar-dilution and agar-well techniques were performed. The ethanol extract was more effective against Botrytis cinerea and Mucor sp. when the agar-well method was used. However, when using the agar-dilution method the ethanol extract of Agave scabra inhibited the growth of Botrytis cinerea, Mucor sp. and Penicillium sp. 相似文献
89.
C Magnoli SM Chiacchiera R Miazzo G Palacio A Angeletti C Hallak A Dalcero 《Mycotoxin Research》2002,18(1):7-22
Feedstuffs used for poultry nutrition in Argentina were analyzed for fungal flora and natural incidence of mycotoxins. Survey
of 120 samples of poultry feeds, taken from May 1998 to April 1999, showed the presence of 15 genera of filamentous fungi.
The predominant genera wereFusarium spp. andPenicillium ssp., isolated in 67.5 % of the samples, followed byAspergillus spp. (57.5 %). Yeast, were significantly isolated from most of the samples. Species identification was carried down for the
toxigenic genera. Fungal total counts of poultry feeds ranged from 2.0 × 103 to 3.0 × 105 CFU g-1 The fungal total counts during two months of sampling, were slightly over the limit value of 1 × 105 CFU g-1, which ensure the hygienic quality of the feed. Potentially toxicogenic species presented moderate mean colony counts. Many
of the fungi isolated from poultry feeds are mycotoxin producers. Fumonisins had the highest incidence, and were found in
97 % of the analyzed samples followed by aflatoxin B1 (46 %), zearalenone (18 %) and deoxynivalenol (6 %). On the co-occurrence of both carcinogenic mycotoxins, all of the FBs
contaminated feed samples were co-contaminated with AFB1. The results show the relevance of the samples screening for viable fungi propagules and the surveillance of their associated
mycotoxins in poultry feeds. 相似文献
90.
Root oil of Ligusticum grayi (Apiaceae) contains numerous irregular sesquiterpenoids. In addition to the known acyclic sesquilavandulol and a sesquilavandulyl aldehyde, two thapsanes, one epithapsane, and 14 sesquiterpenoids representing eight hitherto unknown carbon skeletons were found. These skeletons are: prethapsane, i.e. 1,1,2,3a,7,7-hexamethyloctahydro-1H-indene; isothapsane, i.e. 1,2,3a,6,7,7a-hexamethyloctahydro-1H-indene; ligustigrane, i.e. 1,1,2,7,7,7a-hexamethyloctahydro-1H-indene; isoligustigrane, i.e. 1,1,2,6,7,7a-hexamethyloctahydro-1H-indene; preisothapsane, i.e. 1,1,2,3a,6,7-hexamethyloctahydro-1H-indene; isoprethapsane, i.e. 1,1,2,4,7,7-hexamethyloctahydro-1H-indene; allothapsane, i.e. 1,1,2,3a,7,7a-hexamethyloctahydro-1H-indene; and oshalagrane, i.e. 1,1,2,4,6,6-hexamethylspiro[4.4]nonane.The bicyclic sesquiterpenoids are presumably biosynthesized by head-to-head coupling of geranyl diphosphate and dimethylallyl diphosphate, followed by a cyclization sequence leading to a hydroindane skeleton with six one-carbon substituents. Subsequent rearrangements—primarily methyl migrations—account for the remarkable variety of structures represented in L. grayi root oil. 相似文献