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21.
Bernardo Celda Clelia Biamonti Maria Jose Arnau Roberto Tejero Gaetano T. Montelione 《Journal of biomolecular NMR》1995,5(2):161-172
Summary A large portion of the 13C resonance assignments for murine epidermal growth factor (mEGF) at pH 3.1 and 28°C has been determined at natural isotope abundance. Sequence-specific 13C assignments are reported for 100% of the assignable C, 96% of the C, 86% of the aromatic and 70% of the remaining peripheral aliphatic resonances of mEGF. A good correlation was observed between experimental and back-calculated C chemical shifts for regions of regular -sheet structure. These assignments also provide the basis for interpreting 1H–13C heteronuclear NOE (HNOE) values in mEGF at natural isotope abundance. Some of the backbone polypeptide segments with high internal mobility, indicated by these 1H–13C HNOE measurements, correlate with locations of residues involved in the putative mEGF-receptor binding site. Using four families of mEGF structures obtained over the last few years, we demonstrate that standard deviations between experimental and back-calculated C values can be used to monitor the refinement of this protein's structure, particularly for -sheet regions. Improved agreement between calculated and observed values of C is correlated with other measures of structure quality, including lowered values of residual constraint violations and more negative values of conformational energy. These results support the view that experimental conformation-dependent chemical shifts, C, can provide a reliable source of information for monitoring the process of protein structure refinement and are potentially useful restraints for driving the refinement.Abbreviations HSQC
heteronuclear single-quantum coherence spectroscopy
- PFG
pulsed-field gradient
- TOCSY
1H-1H total correlation spectroscopy
- EGF
epidermal growth factor
- mEGF
murine EGF
- hEGF
human EGF
- hTGF
human type- transforming growth factor
- DIPSI
spm-locking pulse sequence
- NOE
nuclear Overhauser effect
- HNOE
heteronuclear Overhauser effect 相似文献
22.
Neville J. Pinfield Jesus O. Sanchez-Torres Christopher N. McDermott 《Plant Growth Regulation》1984,2(2):99-109
Swelling of the hypocotyl base induced by 2,4-D in seedlings of marrow was much reduced if GA3 was also present in the incubation medium. At appropriate concentrations kinetin also counteracted this 2,4-D effect, although at higher concentrations appeared to be ineffective. GA3 was also able to overcome the inhibitory effects of 2,4-D on extension growth in the hypocotyl but kinetin was much less effective in this case. None of the treatments employed was able to alleviate the inhibition of radicle extension induced by 2,4-D.Ethephon induced similar responses in the seedlings to those resulting from 2,4-D treatment, while treatment with a mixture of 2,4-D and CoCl2 removed many of these growth abnormalities. These observations are interpreted as indicating that 2,4-D operates at least partly by stimulating the production of ethylene in the tissues. 2,4-D strongly inhibited the accumulation of endogenous gibberellin during the period of seedling development examined, but enhanced cytokinin levels during the later stages of the same period. The possibility of interactions at the biosynthetic level between gibberellins, cytokinins and ethylene and their involvement in the regulation of seedling development are discussed. 相似文献
23.
We assessed the effects of cold and isolation stress on arginine vasopressin (AVP) mRNA in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. Vasopressin mRNA levels were determined by in situ hybridization histochemistry at the cellular level. In posterior magnocellular neurons of the PVN isolation stress for 7 or 14 days increased vasopressin mRNA levels 28 and 29%, respectively, compared to group-housed controls. No significant alterations in vasopressin gene expression were observed in the SON after 7 or 14 days of isolation stress. Scattered magnocellular AVP mRNA-expressing cells of the medial parvocellular PVN showed increases of 19 and 34% after 7 and 14 days of isolation, respectively. We also studied the effect of cold or combined cold and isolation stress on vasopressin gene expression in the PVN and SON. Cold stress for 3 h daily for 4 consecutive days increased AVP mRNA levels in the posterior magnocellular PVN by 15%. Cold-isolated animals showed an increase of 21%. No significant effect on AVP mRNA levels in the SON was observed. In contrast to the posterior magnocellular PVN, cold or cold-isolation stress increased AVP mRNA in magnocellular neurons of the medial parvocellular region of the PVN by 25 and 43%, respectively, relative to control rats. These results suggest that psychological and metabolic stress may be added to the list of stressors that activate the hypothalamo-neurohypophysial system. 相似文献
24.
Soledad Gaitán Elvira Cuenllas Pilar Sancho Juan A. Bueren Concepción Tejero 《Bioscience reports》1992,12(4):281-292
This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. Anin vivo andin vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes. 相似文献
25.
E J Van Zoelen C Henriques de Jesus E de Jonge M Mulder M C Blok J de Gier 《Biochimica et biophysica acta》1978,511(3):335-347
1. The reflection coefficient for the permeation of thiourea through bilayers of phosphatidylcholine is a function of the fatty-acid composition of the lipid molecules. By means of these reflection coefficients an index for membrane fluidity has been given to each of those lipids, relative to that of egg phosphatidylcholine. 2. The maximum number of water molecules that can copermeate with each molecule of solute by means of solute-solvent interaction is a function of the packing of the lipid molecules in the bilayer. This parameter has been used in this paper for characterizing the fluidity of cholesterol-containing membranes and for membranes with their lipids in the gel state. 相似文献
26.
Summary The dryness-induced ultrastructural changes of both myco- and phycobiont of three lichen species (R. geographicum, P. conspersa, andU. pustulata) have been studied over three months and half, period of time. During this time other ecological factors, such as rock substratum, temperature, light and gas interchange were unaltered compared to the natural conditions. A large number of ultrastructural changes were observed in the mycobiont as well as in the phycobiont (Trebouxia) and often, cells showed a highly disorganized morphology. The most important ultrastructural modifications were: 1. pyrenoglobuli of the algae were peripheral, 2. new and unknown structures were observed in the phycobionts of bothR. geographicum andU. pustulata as well as in the mycobiont of the latter species. 相似文献
27.
Clonal descent and microevolution of Neisseria meningitidis during 30 years of epidemic spread 总被引:3,自引:0,他引:3
Giovanna Morelli Burkhard Malorny Kerstin Müller rea Seiler Jian-Fu Wang Jesus del Valle & Mark Achtman 《Molecular microbiology》1997,25(6):1047-1064
Serogroup A meningococci of subgroups III, IV-1 and IV-2 are probably descended from a common ancestor that existed in the nineteenth century. The 10.5 kb sequences spanning five distinct chromosomal loci, encoding cell-surface antigens, a secreted protease or housekeeping genes and intergenic regions, were almost identical in strains of those subgroups isolated in 1966, 1966 and 1917 respectively. During the subsequent two to three decades, all of these loci varied as a result of mutation, translocation or import of DNA from unrelated neisseriae. Thus, microevolution occurs frequently in naturally transformable bacteria. Many variants were isolated only once or within a single geographical location and disappeared thereafter. Other variants achieved genetic fixation within months or a few years. The speed with which sequence variation is either eliminated or fixed may reflect sequential bottlenecks associated with epidemic spread and contrasts with the results of phylogenetic analyses from bacteria that do not cause epidemics. 相似文献
28.
Kalina T. J. Davies Laurel R. Yohe Jesus Almonte Miluska K. R. Snchez Edgardo M. Rengifo Elizabeth R. Dumont Karen E. Sears Liliana M. Dvalos Stephen J. Rossiter 《Molecular ecology》2020,29(10):1839-1859
Changes in behaviour may initiate shifts to new adaptive zones, with physical adaptations for novel environments evolving later. While new mutations are commonly considered engines of adaptive change, sensory evolution enabling access to new resources might also arise from standing genetic diversity, and even gene loss. We examine the relative contribution of molecular adaptations, measured by positive and relaxed selection, acting on eye‐expressed genes associated with shifts to new adaptive zones in ecologically diverse bats from the superfamily Noctilionoidea. Collectively, noctilionoids display remarkable ecological breadth, from highly divergent echolocation to flight strategies linked to specialized insectivory, the parallel evolution of diverse plant‐based diets (e.g., nectar, pollen and fruit) from ancestral insectivory, and—unusually for echolocating bats—often have large, well‐developed eyes. We report contrasting levels of positive selection in genes associated with the development, maintenance and scope of visual function, tracing back to the origins of noctilionoids and Phyllostomidae (the bat family with most dietary diversity), instead of during shifts to novel diets. Generalized plant visiting was not associated with exceptional molecular adaptation, and exploration of these novel niches took place in an ancestral phyllostomid genetic background. In contrast, evidence for positive selection in vision genes was found at subsequent shifts to either nectarivory or frugivory. Thus, neotropical noctilionoids that use visual cues for identifying food and roosts, as well as for orientation, were effectively preadapted, with subsequent molecular adaptations in nectar‐feeding lineages and the subfamily Stenodermatinae of fig‐eating bats fine‐tuning pre‐existing visual adaptations for specialized purposes. 相似文献
29.
Colares Tamiris Gago de Figueiredo Camila Saggioro de Oliveira Jesus Souza Lucienne dos Santos Aline Araujo Giestal-de-Araujo Elizabeth 《Neurochemical research》2021,46(7):1701-1716
Neurochemical Research - Interleukin-2 (IL-2) is a classical pro-inflammatory cytokine known to display neuroprotective roles in the central nervous system including the retina. In the present... 相似文献
30.
James F. Markworth Lemuel A. Brown Eunice Lim Jesus A. CastorMacias Jacqueline Larouche Peter C. D. Macpherson Carol Davis Carlos A. Aguilar Krishna Rao Maddipati Susan V. Brooks 《Aging cell》2021,20(6)
Specialized pro‐resolving mediators actively limit inflammation and support tissue regeneration, but their role in age‐related muscle dysfunction has not been explored. We profiled the mediator lipidome of aging muscle via liquid chromatography‐tandem mass spectrometry and tested whether treatment with the pro‐resolving mediator resolvin D1 (RvD1) could rejuvenate the regenerative ability of aged muscle. Aged mice displayed chronic muscle inflammation and this was associated with a basal deficiency of pro‐resolving mediators 8‐oxo‐RvD1, resolvin E3, and maresin 1, as well as many anti‐inflammatory cytochrome P450‐derived lipid epoxides. Following muscle injury, young and aged mice produced similar amounts of most pro‐inflammatory eicosanoid metabolites of cyclooxygenase (e.g., prostaglandin E2) and 12‐lipoxygenase (e.g., 12‐hydroxy‐eicosatetraenoic acid), but aged mice produced fewer markers of pro‐resolving mediators including the lipoxins (15‐hydroxy‐eicosatetraenoic acid), D‐resolvins/protectins (17‐hydroxy‐docosahexaenoic acid), E‐resolvins (18‐hydroxy‐eicosapentaenoic acid), and maresins (14‐hydroxy‐docosahexaenoic acid). Similar absences of downstream pro‐resolving mediators including lipoxin A4, resolvin D6, protectin D1/DX, and maresin 1 in aged muscle were associated with greater inflammation, impaired myofiber regeneration, and delayed recovery of strength. Daily intraperitoneal injection of RvD1 had minimal impact on intramuscular leukocyte infiltration and myofiber regeneration but suppressed inflammatory cytokine expression, limited fibrosis, and improved recovery of muscle function. We conclude that aging results in deficient local biosynthesis of specialized pro‐resolving mediators in muscle and that immunoresolvents may be attractive novel therapeutics for the treatment of muscular injuries and associated pain in the elderly, due to positive effects on recovery of muscle function without the negative side effects on tissue regeneration of non‐steroidal anti‐inflammatory drugs. 相似文献