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51.
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52.
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
53.
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
54.
The biotin repressor is an allosterically regulated, site-specific DNA-binding protein. Binding of the small ligand bio-5′-AMP activates repressor dimerization, which is a prerequisite to DNA binding. Multiple disorder-to-order transitions, some of which are known to be important for the functional allosteric response, occur in the vicinity of the ligand-binding site concomitant with effector binding to the repressor monomer. In this work, the extent to which these local changes are coupled to additional changes in the structure/dynamics of the repressor was investigated using hydrogen/deuterium exchange coupled to mass spectrometry. Measurements were performed on the apo-protein and on complexes of the protein bound to four different effectors that elicit a range of thermodynamic responses in the repressor. Global exchange measurements indicate that binding of any effector to the intact protein is accompanied by protection from exchange. Mass spectrometric analysis of pepsin-cleavage products generated from the exchanged complexes reveals that the protection is distributed throughout the protein. Furthermore, the magnitude of the level of protection in each peptide from hydrogen/deuterium exchange correlates with the magnitude of the functional allosteric response elicited by a ligand. These results indicate that local structural changes in the binding site that occur concomitant with effector binding nucleate global dampening of dynamics. Moreover, the magnitude of dampening of repressor dynamics tracks with the magnitude of the functional response to effector binding. 相似文献
55.
Background
The transglutaminase activated factor XIII (FXIIIa) acts to strengthen pathological fibrin clots and to slow their dissolution, in part by crosslinking active α2-antiplasmin (α2AP) to fibrin. We previously reported that a yeast-derived recombinant fusion protein comprising α2AP residues 13-42 linked to human serum albumin (HSA) weakened in vitro clots but failed to become specifically incorporated into in vivo clots. In this study, our aims were to improve both the stability and clot localization of the HSA fusion protein by replacing α2AP residues 13-42 with shorter sequences recognized more effectively by FXIIIa.Results
Expression plasmids were prepared encoding recombinant HSA with the following N-terminal 23 residue extensions: H6NQEQVSPLTLLAG4Y (designated XL1); H6DQMMLPWAVTLG4Y (XL2); H6WQHKIDLPYNGAG4Y (XL3); and their 17 residue non-His-tagged equivalents (XL4, XL5, and XL6). The HSA moiety of XL4- to XL6-HSA proteins was C-terminally His-tagged. All chimerae were efficiently secreted from transformed Pichia pastoris yeast except XL3-HSA, and following nickel chelate affinity purification were found to be intact by amino acid sequencing, as was an N-terminally His-tagged version of α2AP(13-42)-HSA. Of the proteins tested, XL5-HSA was cross-linked to biotin pentylamine (BPA) most rapidly by FXIIIa, and was the most effective competitor of α2AP crosslinking not only to BPA but also to plasma fibrin clots. In the mouse ferric chloride vena cava thrombosis model, radiolabeled XL5-HSA was retained in the clot to a greater extent than recombinant HSA. In the rabbit jugular vein stasis thrombosis model, XL5-HSA was also retained in the clot, in a urea-insensitive manner indicative of crosslinking to fibrin, to a greater extent than recombinant HSA.Conclusions
Fusion protein XL5-HSA (DQMMLPWAVTLG4Y-HSAH6) was found to be more active as a substrate for FXIIIa-mediated transamidation than seven other candidate fusion proteins in vitro. The improved stability and reactivity of this chimeric protein was further evidenced by its incorporation into in vivo clots formed in thrombosis models in both mice and rabbits. 相似文献56.
Sahar Behzad Antoni Sureda Davide Barreca Seyed Fazel Nabavi Luca Rastrelli Seyed Mohammad Nabavi 《Phytochemistry Reviews》2017,16(3):527-533
Dihydrochalcones are a class of secondary metabolites, whose demand in biological and pharmacological applications is rapidly growing. Phloretin is one of the best known and abundant dihydrochalcone characterized by the presence of 2,6-dihydroxyacetophenone pharmacophore. It is a versatile molecule with anticancer, antiosteoclastogenic, antifungal, antiviral, anti-inflammatory, antibacterial and estrogenic activities and able to increase the fluidity of biological membranes and penetration of administered drugs. In this review we have performed a critical evaluation of available literature as far as phloretin beneficial effects and activation/block of intracellular signal cascade are of concern. In addition, we supply useful information on its chemical properties, sources and bioavailability. 相似文献
57.
58.
59.
S Avidon SM Marr TA Bellingan KJ Esler OLF Weyl 《African Journal of Aquatic Science》2018,43(3):313-318
We evaluated the impact of non-native rainbow trout Oncorhynchus mykiss on a population of endemic Cedarberg ghost frog Heleophryne depressa in the upper Krom River (Olifants-Doring River Catchment, Cape Fold Ecoregion). We compared H. depressa abundance (using kick-sampling and underwater video analysis) and environmental conditions between sites above and below a waterfall that marks the upper distribution limit of O. mykiss. Heleophryne depressa abundance was significantly greater above the waterfall than that below it, and, because there was no significant difference in measured environmental variables, O. mykiss presence is identified as the most likely explanation for the observed decrease in H. depressa abundance. 相似文献
60.
B. Abtahi H. Nabavi V. Jafari-Shamushaki R. Gorbani A. O. Kasumyan 《Journal of Ichthyology》2018,58(2):248-254
The present paper studies the effects of sublethal concentrations of two neurotoxic insecticides (diazinon and endosulfan, duration of exposure 48 h) on the taste attractiveness of L-histidine (0.1 M), L-cysteine (0.1 M), and L-asparagine acid (0.01 M) for juvenile Persian sturgeon Acipenser persicus. The study revealed different effects of diazinon and endosulfan on the extraoral and intraoral taste reception in fish. The taste responses determined by the extraoral taste system (frequency of grasping of 50 food pellets for 5 min of trial) following exposure to endosulfan are the same as in the intact specimens. The exposure to diazinon leads to two to fourfold increase in the number of grasping the pellets, while the amino acids become tasteattractive as opposed to the intact specimens. Both insecticides affect the taste responses controlled by the intraoral taste reception. The insecticide-related pathology is expressed either as a sharp (tens of times) decrease in the absolute and relative consumption of all types of pellets or as full rejection of the pellets after their grasping. Furthermore, the intraoral taste properties of amino acids remain the same as in the intact fish. 相似文献