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71.
Orexin-A and orexin-B orchestrate their diverse central and peripheral effects via two G-protein coupled receptors, OX1R and OX2R, which activate multiple G-proteins. In many tissues, orexins activate extracellular signal-regulated kinase (ERK(1/2)) and p38 mitogen-activated protein kinase (MAPK); however, the mechanism by which OX2R alone mediates MAPK activation is not understood. This study describes the intracellular signalling pathways involved in OX2R-mediated ERK(1/2) and p38 MAPK activation. In HEK-293 cells stably over-expressing recombinant human OX2R, orexin-A/B resulted in a rapid, dose and time dependent increase in activation of ERK(1/2) and p38 MAPK, with maximal activation at 10 min for ERK(1/2) and 30 min for p38 MAPK. Using dominant-negative G-proteins and selective inhibitors of intracellular signalling cascades, we determined that orexin-A and orexin-B induced ERK(1/2) and p38 MAPK activation through multiple G-proteins and different intracellular signalling pathways. ERK(1/2) activation involves Gq/phospholipase C (PLC)/protein kinase C (PKC), Gs/adenylyl cyclase (AC)/cAMP/protein kinase A (PKA) and Gi cascades; however, the Gq/PLC/PKC pathway, as well as PKA is not required for OX2R-mediated p38 MAPK activation. Interestingly, orexin-B-induced ERK(1/2) activation is predominantly mediated through the Gq/PLC/PKC pathway. In conclusion, this is the first comprehensive signalling study of the human OX2R recombinant receptor, showing ERK(1/2) and p38 MAPK activation are regulated by differential signalling pathways in HEK-293 cells, and that the ERK(1/2) activation is severely affected by naturally occurring mutants associated with narcolepsy. Moreover, it is evident that the human OX2R has ligand specific effects, with orexin-B being more potent in this transfected system and this distinct modulation of the MAPKs through OX2R, may translate to the regulation of diverse biological actions of orexins. 相似文献
72.
73.
Background
There are a number of difficulties associated with the study of adaptation. One is a lack of variation in the trait, which is common in adaptations because past selection has removed unfit variants. This lack of variation makes it difficult to determine the relationship between trait variation and fitness. Another difficulty is proving causation in this trait–fitness relationship, because a correlated trait might be the actual adaptation. These difficulties can be ameliorated at least partially by combining studies of natural variation with studies of experimentally manipulated traits and traits whose variance has been augmented by artificial selection.Scope
We review here a number of our studies on the adaptive value of two aspects of anther position in wild radish (Raphanus raphanistrum, Brassicaceae): anther exsertion, i.e. the degree to which anthers protrude from the mouth of the corolla tube, and anther height dimorphism, i.e. the difference in lengths of the filaments between the two short and four long stamens. We have used both functional analyses, in which the response variable is pollen removal, and measurements of selection, in which the response variable is lifetime male fitness estimated by molecular genetic paternity analyses. In these studies we use both the natural variation in populations as well as manipulated variation, the latter through both stamen removal and artificial selection, to re-create the ancestral trait conditions.Conclusions
Our work provides convincing evidence that intermediate anther exsertion values are adaptive, and that this is probably an adaptation to a subset of the pollinator fauna, small bees. The picture for anther height dimorphism is much less clear, as the weight of current evidence suggests that current values of this trait might actually be maladaptive; however, if this is true it is difficult to understand how the dimorphism is maintained across the family Brassicaceae.Key words: Wild radish, Raphanus raphanistrum, adaptation, natural selection, anther position, pollination, pollen removal 相似文献74.
Physiological functions of beneficial elements 总被引:3,自引:0,他引:3
75.
Gordon W Slysz Charles AH Baker Benjamin M Bozsa Anthony Dang Andrew J Percy Melissa Bennett David C Schriemer 《BMC bioinformatics》2009,10(1):162
Background
Hydrogen/deuterium exchange mass spectrometry (H/DX-MS) experiments implemented to characterize protein interaction and protein folding generate large quantities of data. Organizing, processing and visualizing data requires an automated solution, particularly when accommodating new tandem mass spectrometry modes for H/DX measurement. We sought to develop software that offers flexibility in defining workflows so as to support exploratory treatments of H/DX-MS data, with a particular focus on the analysis of very large protein systems and the mining of tandem mass spectrometry data. 相似文献76.
77.
Facilitating the recovery of phenotypically normal transgenic lines in clonal crops: a new strategy illustrated in potato 总被引:1,自引:0,他引:1
Barrell PJ Conner AJ 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,122(6):1171-1177
Transgenic plants frequently exhibit altered phenotypes, unrelated to transgene expression, which are attributed to tissue
culture-induced variation and/or insertional mutagenesis. Distinguishing between these possibilities has been difficult in
clonal crops such as potato, due to their highly heterozygous background and the resulting inherent phenotypic variability
associated with segregation. This study reports the use of transgene integration as a molecular marker to trace the clonal
origin of single cells in tissue culture. Following transformation, multiple shoots have been regenerated from cell colonies
of potato (Solanum tuberosum L.) and Southern analysis used to confirm their derivation from a single transformed cell. Analysis of phenotypic variation
in field trials has demonstrated marked differences between these multiple regeneration events, the origin of which must have
occurred after T-DNA insertion, and consequently during the tissue culture phase. This result unequivocally demonstrates that
somaclonal variation occurs during tissue culture and independent of transgene insertion. Furthermore, the first shoots recovered
do not necessarily exhibit less somaclonal variation, since later regeneration events can give rise to plants that are more
phenotypically normal. Therefore, when developing transgenic lines for genetic improvement of clonal crops, multiple shoots
should be regenerated and evaluated from each transformation event to facilitate the recovery of phenotypically normal transgenic
lines. 相似文献
78.
He GX Thorpe C Walsh D Crow R Chen H Kumar S Varela MF 《Archives of microbiology》2011,193(10):759-765
We cloned a gene, ECL_03329, from the chromosome of Enterobacter cloacae ATCC13047, using a drug-hypersensitive Escherichia coli KAM32 cell as the host. We show here that this gene, designated as emmdR, is responsible for multidrug resistance in E. cloacae. E. coli KAM32 host cells containing the cloned emmdR gene (KAM32/pEMMDR28) showed decreased susceptibilities to benzalkonium chloride, norfloxacin, ciprofloxacin, levofloxacin, ethidium bromide, acriflavine, rhodamine6G, and trimethoprim. emmdR-deficient E. cloacae cells (EcΔemmdR) showed increased susceptibilities to several of the antimicrobial agents tested. EmmdR has twelve predicted transmembrane segments and some shared identity with members of the multidrug and toxic compound extrusion (MATE) family of transporters. Study of the antimicrobial agent efflux activities revealed that EmmdR is an H+-drug antiporter but not a Na+ driven efflux pump. These results indicate that EmmdR is responsible for multidrug resistance and pumps out quinolones from E. cloacae. 相似文献
79.
L. Mike Conner Steven B. Castleberry Anna M. Derrick 《The Journal of wildlife management》2011,75(4):938-944
Control of mid-sized mammalian predators (hereafter, mesopredators) is sometimes advocated in an attempt to reduce their impact on wildlife populations, particularly economically important (i.e., game) or endangered species. However, mesopredators may play a role in regulating small mammal populations; thus, lethal control of mesopredators may have unintended consequences. The hispid cotton rat (Sigmodon hispidus; hereafter, cotton rat) is one of the most common small mammals in the southeastern United States and is an important prey species for several of the region's predators. Within fire-maintained communities, such as the longleaf pine (Pinus palustris) forests of the Coastal Plain, cotton rat populations dramatically, yet temporarily, decline following prescribed fire. To evaluate the effects of mesopredator removal on cotton rat survival and cause-specific mortality, we conducted a large-scale mesopredator exclusion experiment that incorporated a prescribed fire during the winter of study. Between 18 May 2006 and 20 June 2007, we used radio-telemetry to monitor 252 cotton rats (131 in exclosures and 121 in controls) and documented 184 mortalities. During the 37-week period of monitoring prior to the prescribed fire event, weekly survival of cotton rats was greater in mesopredator exclusion plots. During the 19 weeks following the prescribed fire, there were no differences in weekly survival relative to mesopredator treatment, but fire caused a short-term reduction in weekly survival within both exclosures and controls. Of 36 cotton rats monitored on the date of prescribed fire, 18 were depredated within 1 month, 4 emigrated, and 5 were killed by the fire event. Overall, raptors preyed on cotton rats more in exclosures than in controls, but evidence for compensatory predation (raptor-caused morality greater in exclosures than in controls although survival rates were similar between treatments) only occurred following the prescribed fire event. Our results suggest that managing mesopredators may result in a temporary increase in cotton rat survival, but dormant season prescribed fire removes this effect until well into the following growing season. © 2011 The Wildlife Society. 相似文献
80.
Rebecca E. Day Philip Kitchen David S. Owen Charlotte Bland Lindsay Marshall Alex C. Conner Roslyn M. Bill Matthew T. Conner 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014