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991.
Taste, smell, and chemical irritation (so-called trigeminal sensation) combine in our daily experience to produce the supramodal sensation of flavor, are processed by partly overlapping neural mechanisms, and show functional interconnectivity in experiments. Given their collaboration in flavor formation and the well-established connections between these senses, it is plausible that polymodal detection mechanisms might contribute to individual differences in measured sensitivity. One would expect the existence of a general chemosensory sensitivity factor to result in associations among taste, smell, and trigeminal stimulation thresholds. Measures of 5 detection thresholds from all the chemical senses were assessed in the same group of young healthy subjects (n=57). An unbiased principal components analysis (PCA) yielded a 2-component solution. Component 1, on which taste thresholds loaded strongly, accounted for 29.4% of the total variance. Component 2, on which the odor and trigeminal lateralization thresholds loaded strongly, accounted for 26.9% of the total variance. A subsequent PCA restricted to a 3-component solution cleanly separated the 3 sensory modalities and accounted for 75% of the total variance. Thus, though there may be a common underlying factor that determines some individual differences in odor and trigeminal lateralization thresholds, a general chemical sensitivity that spans chemosensory modalities seems unlikely. 相似文献
992.
Lindop R Arentz G Thurgood LA Reed JH Jackson MW Gordon TP 《Immunology and cell biology》2012,90(3):304-309
Ro/SSA and La/SSB comprise a linked set of autoantigens that are clinically important members of the extractable nuclear antigen family and key translational biomarkers for lupus and primary Sj?gren's syndrome. Autoantibodies directed against the Ro60 and La polypeptide components of the Ro/La ribonucleoprotein complex, and the structurally unrelated Ro52 protein, mediate tissue damage in the neonatal lupus syndrome, a model of passively acquired autoimmunity in humans in which the most serious manifestation is congenital heart block (CHB). Recent studies have concentrated on two distinct pathogenic mechanisms by which maternal anti-Ro/La autoantibodies can cause CHB: by forming immune complexes with apoptotic cells in developing fetal heart; and/or by acting as functional autoantibodies that cross-react with and inhibit calcium channels. Although the precise role of the individual autoantibodies is yet to be settled, maternal anti-Ro60 and anti-Ro52 remain the most likely culprits. This article will discuss the molecular pathways that culminate in the development of CHB, including the recent discovery of β2 glycoprotein I as a protective factor, and present a proteomic approach based on direct mass spectrometric sequencing, which may give a more representative snapshot of the idiotype repertoire of these autoantibodies than genomic-based technologies. 相似文献
993.
Federico L Ren H Mueller PA Wu T Liu S Popovic J Blalock EM Sunkara M Ovaa H Albers HM Mills GB Morris AJ Smyth SS 《Molecular endocrinology (Baltimore, Md.)》2012,26(5):786-797
Brown adipose tissue is a thermogenic organ that dissipates stored energy as heat to maintain body temperature. This process may also provide protection from development of diet-induced obesity. We report that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, whereas potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibit reduced expression of brown adipose tissue-related genes in peripheral white adipose tissue and accumulate significantly more fat than wild-type controls when fed a high-fat diet. Our results indicate that ATX and its product LPA are physiologically relevant negative regulators of brown fat adipogenesis and are consistent with a model in which a decrease in mature peripheral brown adipose tissue results in increased susceptibility to diet-induced obesity in mice. 相似文献
994.
We propose a new physical mechanism of cortical rotation generation in one-cell embryos of amphibians based on a phase transition in the ensemble of microtubules localized to the cortical region of the cell interior. Microtubules, protein polymers formed from tubulin heterodimers, are highly negatively charged, which results in strong electrostatic interactions over tens of nanometers, even in the presence of counterions that partially screen electrostatic interactions. A simplified model that offers a plausible representation of these effects is based on the Ising Hamiltonian, which has been robustly applied to explain a wide range of order-disorder transitions in physics, chemistry and other sciences. An Ising model phase transition, especially with the supercooperative flow alignment effect of global rotation of the cortex, provides an alternative to models of cortical rotation based on microtubule polymerization or motor molecules. Insofar as there is any reality to the concept that microtubules are involved in consciousness, we propose that cortical rotation in the one-cell embryo is a better place to look for the purported microtubule entanglement or coherence properties than the adult brain. 相似文献
995.
This paper reports the results of computer modeling of microtubules that end up in the cortical region of a one-cell amphibian embryo, prior to the first cell division. Microtubules are modeled as initially randomly oriented semi-flexible rods, represented by several lines of point-masses interacting with one another like masses on springs with longitudinal and transverse stiffness. They are also considered to be space-filling rods floating in a viscous fluid (cytoplasm) experiencing drag forces and buoyancy from the fluid under a variable gravity field to test gravitational effects. Their randomly distributed interactions with the surrounding spherical container (the cell membrane) have a statistical nonzero average that creates a torque causing a rotational displacement between the cytoplasm and the rigid cortex. The simulation has been done for zero and normal gravity and it validates the observation that cortical rotation occurs in microgravity as well as on Earth. The speed of rotation depends on gravity, but is still substantial in microgravity. 相似文献
996.
Mice, rats, and nearly all mammals and birds are classified as homeothermic, meaning that their core temperature is regulated at a constant level over a relatively wide range of ambient temperatures. In one sense, this homeothermic designation has been confirmed by the advent of radiotelemetry and other techniques that allow for the remote monitoring of awake, unrestrained animals in laboratory or natural settings. This technology confirmed that, when averaged over many hours, core temperature of mammals is regulated at a nearly constant level. On the other hand, telemetric sampling in relatively small mammals such as mice and rats also revealed that their core temperature often varies markedly from hour to hour. In other words, the mouse could be defined as a homeotherm only when core temperature is averaged over a relatively long period. Many researchers ascribe equal homeothermic capabilities to mice and other small rodents as they do to humans. Such an assumption could lead to errors in extrapolating physiological, pharmacological, and toxicological findings from experimental test species to humans. 相似文献
997.
Ingmar Bürstel Elisabeth Siebert Gordon Winter Philipp Hummel Ingo Zebger B?rbel Friedrich Oliver Lenz 《The Journal of biological chemistry》2012,287(46):38845-38853
Hydrogen-cycling [NiFe] hydrogenases harbor a dinuclear catalytic center composed of nickel and iron ions, which are coordinated by four cysteine residues. Three unusual diatomic ligands in the form of two cyanides (CN−) and one carbon monoxide (CO) are bound to the iron and apparently account for the complexity of the cofactor assembly process, which involves the function of at least six auxiliary proteins, designated HypA, -B, -C, -D, -E, and -F. It has been demonstrated previously that the HypC, -D, -E, and -F proteins participate in cyanide synthesis and transfer. Here, we show by infrared spectroscopic analysis that the purified HypCD complexes from Ralstonia eutropha and Escherichia coli carry in addition to both cyanides the CO ligand. We present experimental evidence that in vivo the attachment of the CN− ligands is a prerequisite for subsequent CO binding. With the aid of genetic engineering and subsequent mutant analysis, the functional role of conserved cysteine residues in HypD from R. eutropha was investigated. Our results demonstrate that the HypCD complex serves as a scaffold for the assembly of the Fe(CN)2(CO) entity of [NiFe] hydrogenase. 相似文献
998.
The southern house mosquito, Culex quinquefasciatus Say, is a competent vector of human disease and an important target of mosquito abatement programs. However, these management programs have been compromised by development of insecticide resistance. In the current study, susceptibilities to naled and resmethrin, two adulticides used in mosquito abatement, were monitored using a topical and contact bioassay, respectively, in five field- collected populations of C. quinquefasciatus (MARC, HOOD1, HOOD2, MINLOVE, and THIB). Frequencies of resistance, measured as survival after treatment with discriminating concentrations (i.e., sufficient to kill > 90% of a reference susceptible strain) were high (88.0-96.8%) in all field collections treated with naled, but were variable (3.3-94.2%) with resmethrin. In addition, esterase activities in mosquitoes from these collections were quantified using alpha-naphthyl acetate and ranged from 1.08 to 3.39 micromol alpha-naphthol produced min(-1) mg prot(-1). Heightened activities were associated with decreased insecticide susceptibility in HOOD1, THIB, and MINLOVE but not HOOD2. Esterases were visualized using native polyacrylamide gel electrophoresis, and intra- and interstrain differences in banding patterns were detected. In addition, esterases from MINLOVE mosquitoes were more numerous and intensely staining when compared with those from a laboratory-susceptible strain. Finally, naled synergized the toxicity of resmethrin in populations with decreased insecticide susceptibility and increased esterase activity by 2.5-(MINLOVE) to three-fold (THIB). Results from this study will allow management strategies for populations of C. quinquefasciatus to be optimized, and provide a foundation for further studies exploring use of esterase inhibitors as synergists of pyrethroid toxicity. 相似文献
999.
Gordon SP López-Sepulcre A Reznick DN 《Evolution; international journal of organic evolution》2012,66(3):912-918
Evolutionary theory predicts that the sex linkage of sexually selected traits can influence the direction and rate of evolutionary change, and also itself be subject to selection. Theory abounds on how sex-specific selection, mate choice, or other phenomena should favor different types of sex-linked inheritance, yet evidence in nature remains limited. Here, we use hormone assays in Trinidadian guppies to explore the extent to which linkage of male coloration differs among populations adapted to varying predation regimes. Results show there is consistently higher degree of X- and autosomal linkage in body coloration among populations adapted to low-predation environments. More strikingly, analyses of an introduced population of guppies from a high- to a low-predation environment suggest that this difference can change in 50 years or less. 相似文献
1000.
Perera OP Snodgrass GL Allen KC Jackson RE Becnel JJ O'Leary PF Luttrell RG 《Journal of invertebrate pathology》2012,109(1):11-19
The complete genome sequence of a single-stranded RNA virus infecting the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), was identified by sequencing cDNA prepared from insects collected from the Mississippi Delta. The 9655 nucleotide positive-sense single-stranded RNA genome of the L. lineolaris single-stranded RNA virus (LyLV-1) contained a single open reading frame of 8958 nucleotides encoding a 2986 amino acid genome polypeptide. The open reading frame was flanked by untranslated regions of 603 and 69 nucleotides at the 5'- and 3'- ends of the genome, respectively. Database searches and homology based modeling was used to identify four capsid proteins (VP1-VP4), helicase/AAA-ATPase, cysteine protease (C3P), protease 2A, and the RNA-directed RNA polymerase (RdRp). In addition, a region with weak similarity to the eukaryotic structural maintenance of chromosome (SMC) domain was identified near the amino-terminal of the polyprotein and adjacent to the VP1 domain. The amino acid sequence of LyLV-1 was approximately 44.4% similar to that of sacbrood virus (SBV) of the honey bee. The genomic organization of both viruses showed remarkable similarity with the exception of highly divergent amino acid regions flanking fairly conserved structural and non-structural polypeptide regions. High similarity to the SBV genome and similarities in the genome organization and amino acid sequence with the viruses of the family Iflaviridae suggested that LyLV-1 was a novel member of this family. Virus particles were 39 nm in diameter and appeared to transmit vertically via eggs. Although this virus may only cause covert infections under normal conditions, the potential for using this virus in biological control of L. lineolaris is discussed. 相似文献