Methyl linoleate oxidation in the presence of bovine serum albumin   总被引：1，自引：0，他引：1  

Hidalgo FJ  Zamora R 《Journal of agricultural and food chemistry》2002,50(19):5463-5467

The oxidation of methyl linoleate (LMe) in the presence of bovine serum albumin (BSA) was studied to analyze both the processes involved when lipid oxidation occurs in the presence of proteins and the relative progression of the several reactions implicated. The disappearance of LMe, the formation of primary and secondary lipid oxidation products, the loss of essential amino acids, and the production of oxidized lipid/amino acid reaction products (OLAARPs) were studied as a function of incubation time. During the first steps of lipid oxidation, LMe was converted quantitatively to methyl linoleate hydroperoxides, which were very rapidly degraded to either secondary products of lipid oxidation or OLAARPs. No significant differences were identified in the major lipid oxidation products formed in incubations with or without proteins, indicating that mechanisms for formation of these compounds are similar in both cases. In addition, no significant differences were observed between the time-courses of formation of secondary oxidation products and OLAARPs, suggesting that hydroperoxide decomposition and OLAARP formation occur simultaneously when the lipid oxidation process takes place in the presence of proteins. Furthermore, OLAARP formation seems to be an unavoidable process that should be considered as a last step in the lipid peroxidation process.  相似文献   

Antiradical efficiency of Maillard reaction mixtures in a hydrophilic media     

Morales FJ  Babbel MB 《Journal of agricultural and food chemistry》2002,50(10):2788-2792

The Maillard reaction (MR) has a clear impact in food science, nutrition, and medical research. Free radical scavenging capacities of several MR mixtures made from single combinations of glucose or lactose and amino acids (gly, his, lys, trp, met, and cys) were evaluated by using the N,N-dimethyl-p-phenylenediamine radical cation assay. Medium-roasted coffee brew was used as reference of a thermally processed food. A novel approach has been applied in order to get more information about the kinetic behavior of the radical scavenging properties of MR mixtures in a watery environment. Antiradical efficiency (AE) concept has been applied, and it takes into consideration the reaction time, apart from the amount of antioxidant necessary to decrease by 50% the radical initial concentration (EC(50)). Cysteine and histidine reveal as powerful amino acids to exert a high AE in the MR mixtures. No relationship between AE parameter and browning was observed.  相似文献   

Atmospheric science. In search of balance     

Charlson RJ  Valero FP  Seinfeld JH 《Science (New York, N.Y.)》2005,308(5723):806-807

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Wind as a long-distance dispersal vehicle in the Southern Hemisphere     

Muñoz J  Felicísimo AM  Cabezas F  Burgaz AR  Martínez I 《Science (New York, N.Y.)》2004,304(5674):1144-1147

Anisotropic (direction-dependent) long-distance dispersal (LDD) by wind has been invoked to explain the strong floristic affinities shared among landmasses in the Southern Hemisphere. Its contribution has not yet been systematically tested because of the previous lack of global data on winds. We used global winds coverage from the National Aeronautics and Space Administration SeaWinds scatterometer to test whether floristic similarities of Southern Hemisphere moss, liverwort, lichen, and pteridophyte floras conform better with (i) the anisotropic LDD hypothesis, which predicts that connection by "wind highways" increases floristic similarities, or (ii) a direction-independent LDD hypothesis, which predicts that floristic similarities among sites increase with geographic proximity. We found a stronger correlation of floristic similarities with wind connectivity than with geographic proximities, which supports the idea that wind is a dispersal vehicle for many organisms in the Southern Hemisphere.  相似文献   

The forest conversion process: A discussion of the sustainability of predominant land uses associated with frontier expansion in the Amazon     

Francisco J. Pichón 《Agriculture and Human Values》1996,13(1):32-51

One of the most striking features observed throughout tropical agricultural frontiers is the extreme variability in land-use strategies from one farmer to the next. This article analyzes the forest conversion process and predominant land uses associated with smallholder settlement expansion in the Amazon frontier. The discussion seeks to increase understanding of the micro and macro-level forces that propel land-use decisions in the Amazon and offer insights about how farmers' land-use decisions may be altered to bring about forms of resource use that are consistent with the constraints and opportunities of the frontier environment. Recognizing that no frontier area can be truly representative of the Amazon as a whole, this article also introduces some detailed evidence from another Amazon country (Ecuador) within a topic that has been previously dominated by research mainly in Brazil. The analysis suggests that to be effective, any policy or technology-based effort on the part of governments or researchers to alter colonist land-use systems must begin to look systematically at the production systems of agricultural colonist populations already present in frontier environments. This knowledge is essential to understand the social and economic factors affecting present land use and choice of technology. It is also important for understanding factors influencing farmers' demand for more optimal systems of land use that are consistent with varying agroecological potentials, demographic situations, and the management capacity of the farmer.  相似文献   

Structural biology. Force and voltage sensors in one structure     

Bezanilla F  Perozo E 《Science (New York, N.Y.)》2002,298(5598):1562-1563

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Inactivation of the interoceptive insula disrupts drug craving and malaise induced by lithium     

Contreras M  Ceric F  Torrealba F 《Science (New York, N.Y.)》2007,318(5850):655-658

Addiction profoundly alters motivational circuits so that drugs become powerful reinforcers of behavior. The interoceptive system continuously updates homeostatic and emotional information that are important elements in motivational decisions. We tested the idea that interoceptive information is essential in drug craving and in the behavioral signs of malaise. We inactivated the primary interoceptive cortex in amphetamine-experienced rats, which prevented the urge to seek amphetamine in a place preference task. Interoceptive insula inactivation also blunted the signs of malaise induced by acute lithium administration. Drug-seeking and malaise both induced Fos expression, a marker of neuronal activation, in the insula. We conclude that the insular cortex is a key structure in the perception of bodily needs that provides direction to motivated behaviors.  相似文献   

Challenges of modeling ocean basin ecosystems   总被引：1，自引：0，他引：1  

deYoung B  Heath M  Werner F  Chai F  Megrey B  Monfray P 《Science (New York, N.Y.)》2004,304(5676):1463-1466

With increasing pressure for a more ecological approach to marine fisheries and environmental management, there is a growing need to understand and predict changes in marine ecosystems. Biogeochemical and physical oceanographic models are well developed, but extending these further up the food web to include zooplankton and fish is a major challenge. The difficulty arises because organisms at higher trophic levels are longer lived, with important variability in abundance and distribution at basin and decadal scales. Those organisms at higher trophic levels also have complex life histories compared to microbes, further complicating their coupling to lower trophic levels and the physical system. We discuss a strategy that builds on recent advances in modeling and observations and suggest a way forward that includes approaches to coupling across trophic levels and the inclusion of uncertainty.  相似文献   

TDP-43 mutations in familial and sporadic amyotrophic lateral sclerosis   总被引：1，自引：0，他引：1  

Sreedharan J  Blair IP  Tripathi VB  Hu X  Vance C  Rogelj B  Ackerley S  Durnall JC  Williams KL  Buratti E  Baralle F  de Belleroche J  Mitchell JD  Leigh PN  Al-Chalabi A  Miller CC  Nicholson G  Shaw CE 《Science (New York, N.Y.)》2008,319(5870):1668-1672

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disorder characterized pathologically by ubiquitinated TAR DNA binding protein (TDP-43) inclusions. The function of TDP-43 in the nervous system is uncertain, and a mechanistic role in neurodegeneration remains speculative. We identified neighboring mutations in a highly conserved region of TARDBP in sporadic and familial ALS cases. TARDBPM337V segregated with disease within one kindred and a genome-wide scan confirmed that linkage was restricted to chromosome 1p36, which contains the TARDBP locus. Mutant forms of TDP-43 fragmented in vitro more readily than wild type and, in vivo, caused neural apoptosis and developmental delay in the chick embryo. Our evidence suggests a pathophysiological link between TDP-43 and ALS.  相似文献   

Transcription. Proteasome parts at gene promoters     

Ottosen S  Herrera FJ  Triezenberg SJ 《Science (New York, N.Y.)》2002,296(5567):479-481

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