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21.
Restriction-map variation associated with the G6PD polymorphism in natural populations of Drosophila melanogaster 总被引:10,自引:0,他引:10
Restriction-map variation was studied in 126 copies of the G6pd region in X
chromosome lines of Drosophila melanogaster from North America, Europe, and
Africa. Special attention was focused on the distribution of variation
relative to the geographically variable polymorphism for two
electrophoretic variants. Nucleotide heterozygosity as determined by eight
six-cutter restriction enzymes for the 13-kb region is estimated, on the
basis of the worldwide sample, to be 0.065%, which is the lowest value
reported for any comparable region in the D. melanogaster genome.
Significant linkage disequilibrium between electrophoretic alleles and
restriction-site variation is observed for several sites. In contrast to
published studies of other genetic regions, there are large insertions that
reach significant frequencies and are found across considerable geographic
distances. There is a clustering of this variation inside the first large
intervening sequence of the G6PD gene.
相似文献
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Aartjan JW te Velthuis Jeroen F Admiraal Christoph P Bagowski 《BMC evolutionary biology》2007,7(1):129
Background
Development, differentiation and physiology of metazoans all depend on cell to cell communication and subsequent intracellular signal transduction. Often, these processes are orchestrated via sites of specialized cell-cell contact and involve receptors, adhesion molecules and scaffolding proteins. Several of these scaffolding proteins important for synaptic and cellular junctions belong to the large family of membrane-associated guanylate kinases (MAGUK). In order to elucidate the origin and the evolutionary history of the MAGUKs we investigated full-length cDNA, EST and genomic sequences of species in major phyla. 相似文献24.
Swart I Jahng JW Overton JM Houpt TA 《American journal of physiology. Regulatory, integrative and comparative physiology》2002,283(5):R1020-R1026
Food deprivation (FD) increases hypothalamic neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNA levels and decreases proopiomelanocortin (POMC) mRNA levels; refeeding restores these levels. We determined the time course of changes in hypothalamic NPY, AGRP, and POMC mRNA levels on refeeding after 24 h FD in C57BL mice by in situ hybridization. After 24 h deprivation, mice were refed with either chow or a palatable mash containing no calories or were injected with murine leptin (100 microg) without food. Mice were perfused 2 or 6 h after treatment. Food deprivation increased hypothalamic NPY mRNA (108 +/- 6%) and AGRP mRNA (78 +/- 7%) and decreased hypothalamic POMC mRNA (-15 +/- 1%). Refeeding for 6 h, but not 2 h, was sufficient to reduce (but not restore) NPY mRNA, did not affect AGRP mRNA, and restored POMC mRNA levels to ad libitum control levels. Intake of the noncaloric mash had no effect on mRNA levels, and leptin administration after deprivation (at a dose sufficient to reduce refeeding in FD mice) was not sufficient to affect mRNA levels. These results suggest that gradual postabsorptive events subsequent to refeeding are required for the restoration of peptide mRNA to baseline levels after food deprivation in mice. 相似文献
25.
26.
The growth and division of mitochondria during the cell cycle was investigated by a morphometric analysis of electron micrographs of synchronized HeLa cells. The ratio of total outer membrane contour length to cytoplasmic area did not vary significantly during the cell cycle, implying a continuous growth of the mitochondrial outer membrane. The mean fraction of cytoplasmic area occupied by mitochondrial profiles was likewise found to remain constant, indicating that the increase in total mitochondrial volume per cell occurs continuously during interphase, in such a way that the mitochondrial complement occupies a constant fraction( approximately 10-11(percent)) of the volume of the cytoplasm. The mean area, outer membrane contour length, and axis ratio of the mitochondrial profiles also did not vary appreciably during the cell cycle; furthermore, the close similarity of the frequency distributions of these parameters for the six experimental time-points suggested a stable mitochondrial shape distribution. The constancy of both the mean mitochondrial profile area and the number of mitochondrial profiles per unit of cytoplasmic area was interpreted to indicate the continuous division of mitochondria at the level of the cell population. Furthermore, no evidence was found for the occurrence of synchronous mitochondrial growth and division within individual cells. Thus, it appears that, in HeLa cells, there is no fixed temporal relationship between the growth and division of mitochondria and the events of the cell cycle. A number of statistical methods were developed for the purpose of making numerical estimates of certain three-dimensional cellular and mitochondrial parameters. Mean cellular and cytoplasmic volumes were calculated for the six time-points; both exhibited a nonlinear, approx. twofold increase. A comparison of the axis ratio distributions of the mitochondrial profiles with theoretical distributions expected from random sectioning of bodies of various three-dimensional shapes allowed the derivation of an "average" mitochondrial shape. This, in turn, permitted calculations to be made which expressed the two-dimensional results in three-dimensional terms. Thus, the estimated values for the number of mitochondria per unit of cytoplasmic volume and for the mean mitochondrial volume were found to remain constant during the cell cycle, while the estimated number of mitochondria per cell increase approx. twofold in an essentially continuous manner. 相似文献
27.
Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important. 相似文献
28.
Pei-Li Yao Meng-Feng Tsai Yi-Chen Lin Chien-Hsun Wang Wei-Yu Liao Jeremy JW Chen Pan-Chyr Yang 《Respiratory research》2005,6(1):89
Background
Theophylline has been used widely as a bronchodilator for the treatment of bronchial asthma and has been suggested to modulate immune response. While the importance of macrophages in asthma has been reappraised and emphasized, their significance has not been well investigated. We conducted a genome-wide profiling of the gene expressions of macrophages in response to theophylline.Methods
Microarray technology was used to profile the gene expression patterns of macrophages modulated by theophylline. Northern blot and real-time quantitative RT-PCR were also used to validate the microarray data, while Western blot and ELISA were used to measure the levels of IL-13 and LTC4.Results
We identified dozens of genes in macrophages that were dose-dependently down- or up-regulated by theophylline. These included genes related to inflammation, cytokines, signaling transduction, cell adhesion and motility, cell cycle regulators, and metabolism. We observed that IL-13, a central mediator of airway inflammation, was dramatically suppressed by theophylline. Real-time quantitative RT-PCR and ELISA analyses also confirmed these results, without respect to PMA-treated THP-1 cells or isolated human alveolar macrophages. Theophylline, rolipram, etazolate, db-cAMP and forskolin suppressed both IL-13 mRNA expression (~25%, 2.73%, 8.12%, 5.28%, and 18.41%, respectively) and protein secretion (<10% production) in macrophages. These agents also effectively suppressed LTC4 expression.Conclusion
Our results suggest that the suppression of IL-13 by theophylline may be through cAMP mediation and may decrease LTC4 production. This study supports the role of theophylline as a signal regulator of inflammation, and that down regulation of IL-13 by theophylline may have beneficial effects in inflammatory airway diseases. 相似文献29.
Tran-Hung?Thuan Deok-Jin?Jahng Jin-Young?Jung Dong-Jin?Kim Won-Kyoung?Kim Young-Joo?Park Ji-Eun?Kim Dae-Hee?AhnEmail author 《Biotechnology and Bioprocess Engineering》2004,9(5):345-351
We investigated the anaerobic ammonium oxidation (anammox) reaction in a labscale upflow anaerobic sludge blanket (UASB) reactor.
Our aim was to detect and enrich the organisms responsible for the anammox reaction using a synthetic medium that contained
low concentrations of substrates (ammonium and nitrite). The reactor was inoculated with granular sludge collected from a
full-scale anaerobic digestor used for treating brewery wastewater. The experiment was performed during 260 days under conditions
of constant ammonium concentration (50 mg NH4/+-N/L) and different nitrite concentrations (50∼150 mg NO2-N/L). After 200 days, anammox activity was observed in the system. The microorganisms involved in this anammox reaction were
identified as CandidatusB. Anammoxidans andK. Stuttgartiensis using fluorescencein situ hybridization (FISH) method. 相似文献
30.
Aldair JW Pinto Maria M Figueiredo Fabiana L Silva Trycia Martins Marilene SM Michalick Washington L Tafuri Wagner L Tafuri 《Acta veterinaria Scandinavica》2011,53(1):1-8