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941.
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Taurine (Tau), calcium (Ca+2) and opiates each produce antinociception when injected i.t. in mice. This study was initiated to determine whether there is a common mechanism underlying their antinociceptive effects. Using the abdominal stretch assay, the antinociceptive effects of both Tau (12 nmol) and Ca+2 (72 nmol) were antagonized by i.t. TAG (4.4 nmol), a Tau antagonist, but not by i.p. injection of the opiate antagonist naloxone (5 mg/kg). The antinociceptive effects of Tau and Ca+2 correlated with their ability to inhibit the intensity of caudally-directed biting and scratching behaviors produced by i.t. NMDA or kainic acid. The inhibitory effects of both Tau and Ca+2 on the biting and scratching behaviors behaviors induced by substance P or excitatory amino acids were reversed by TAG, suggesting a common mediation by Tau. These data indicate that the antinociceptive effects of both Tau and Ca+2 appear to be mediated, at least in part, by Tau but not by the release of endogenous opioid compounds. In addition, inhibition of chemical irritant-induced nociception may be produced by a simple blockade of excitatory amino acid activity. 相似文献
945.
Prevention of SV40 virus tumorigenesis by irradiated, disrupted and iododeoxyuridine treated tumor cell antigens 总被引:1,自引:0,他引:1
946.
alpha 1-Proteinase inhibitors (alpha 1-PIs) are members of the serpin
superfamily of proteinase inhibitors, and are important in the maintenance
of homeostasis in a wide variety of animal taxa. Previous studies have
shown that in mice (genus Mus), evolution of alpha 1-PIs is characterized
by gene amplification, region-specific concerted evolution, and rapid
accumulation of amino acid substitutions. The latter occurs primarily in
the reactive center, which is the region of the alpha 1-PI molecule that
determines the inhibitor's specificity for target proteinases. The P1
residue within the reactive center, which is methionine in so-called
orthodox alpha 1-PIs and an amino acid other than methionine in unorthodox
alpha 1-PIs, is a primary determinant of inhibitor specificity. In the
present study, we find that the expression of mRNAs encoding unorthodox
alpha 1-PIs is polymorphic within Mus species, i.e., among individuals or
inbred strains. This is in striking contrast to mRNAs that encode orthodox
alpha 1-PIs, whose concentrations are relatively invariant. The
intraspecies variations in mRNA expression represent polymorphisms in the
structure of the alpha 1- PI gene family. The results, taken together with
previously described aspects of alpha 1-PI evolution, indicate that the
dissimilar levels of polymorphism exhibited by orthodox and unorthodox
alpha 1-PIs, which likely have distinct physiological functions, may
reflect different levels of selective constraint. The significance of this
finding to the evolution of gene families is discussed.
相似文献
947.
Amber Carmon Matthew Larson Marta Wayne Ross MacIntyre 《Journal of molecular evolution》2010,70(3):260-265
The PIGSFEAST (PF) exon of the Drosophila dumpy gene is undergoing concerted evolution by the process of unequal crossing over. We have developed a long-range PCR-based
assay to amplify the approximately 12 kb long exon which contains variable numbers of 303 or 306 nt long repeats in a tandem
array. We applied this procedure to mutation accumulation lines of Drosophila melanogaster established by M. Wayne and L. Higgins. Nine new repeat length variants were found in these lines allowing us to measure
the rate of unequal crossing over in the PF exon. The rate, which for several reasons is an underestimate, is 7.05 × 10−4 exchanges per generation. 相似文献
948.
Jennifer K. Olson John Aschoff Alice Goble Shawn Larson Joseph K. Gaydos 《Marine Mammal Science》2020,36(4):1083-1096
Spatial analyses of marine mammal stranding data can be used to identify stranding patterns and improve surveillance and monitoring. Using ArcGIS and SaTScan, we analyzed 12 years (2002–2014) of dead beachcast marine mammals from San Juan County, Washington, to better understand patterns of carcass deposition. We plotted the locations for 631 dead marine mammals and aggregated strandings into 1,000 m segments of shoreline. “Hot spots” included beach segments with significantly higher carcass deposition according to the Getis-Ord Gi* statistic in ArcGIS or beach segments that were encompassed by significant spatial clusters using the discrete Poisson model in SatTScan. We identified 52 hot spots for harbor seals (Phoca vitulina) in ArcGIS and 62 hot spots in SaTScan with 81% agreement between methods. Carcass deposition showed a strong relationship with locations having high proximity to public pedestrian access points, suggesting increased reporting effort in those areas. Stranding frequency was also higher on beach segments with longer fetch and nearly level or gentle slopes. Beaches with these geomorphic characteristics, especially those without high proximity to public access, would be ideal locations to actively survey to improve high quality carcass collection during times of high expected mortality and limited resources. 相似文献
949.
950.
Protein crystallography is the predominately used technique for the determination of the three-dimensional structures of proteins and other macromolecules. In this article, the methodology utilized for the measurement and analysis of the diffraction data from crystals is briefly reviewed. As examples of both the usefulness and difficulties of this technique, the determination of the structures of several photosynthetic pigment–protein complexes is described, namely, the reaction center from purple bacteria, photosystem I and photosystem II from cyanobacteria, the light-harvesting complex II from purple bacteria, and the FMO protein from green bacteria. 相似文献