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1.
1D-IEF analysis of BoLA class I expression using allo-antisera reveals additional complexity 总被引:1,自引:0,他引:1
The use of the bovine allo-antisera in lymphocyte microcytotoxicity assays suggests that there is a single highly polymorphic class I product expressed by the BoLA system encoded by one locus. In contrast, biochemical techniques, such as 1D-IEF, reveal a complex pattern of bands for BoLA class I molecules from each animal. In order to understand the origins of this heterogeneity bovine allo-antisera were used in the immunoprecipitation step of 1D-IEF and the results compared with those from immunoprecipitation using the monoclonal antibody W6/32. By modifying existing protocols to include Gammabind G a range of bovine allo-antisera were used successfully to immunoprecpitate bovine MHC class I molecules. The results indicate that the bovine allo-antisera do not recognize all molecules previously assigned to BoLA class I serotypes by 1D-IEF. Furthermore, some of the allo-antisera immunoprecipitated molecules are not recognized by W6/32 and vice versa. This suggests that more than one polymorphic locus is expressed from the bovine MHC and that each allo-antiserum recognizes molecules encoded by different loci. Examination of the results also suggests the existence of linkage disequilibrium in the BoLA class I region. 相似文献
2.
For several species of lepidoptera, most of the approximately 350-bp
mitochondrial control-region sequences were determined. Six of these
species are in one genus, Jalmenus; are closely related; and are believed
to have undergone recent rapid speciation. Recent speciation was supported
by the observation of low interspecific sequence divergence. Thus, no
useful phylogeny could be constructed for the genus. Despite a surprising
conservation of control-region length, there was little conservation of
primary sequences either among the three lepidopteran genera or between
lepidoptera and Drosophila. Analysis of secondary structure indicated only
one possible feature in common--inferred stem loops with higher-than-random
folding energies-- although the positions of the structures in different
species were unrelated to regions of primary sequence similarity. We
suggest that the conserved, short length of control regions is related to
the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In
addition, determination of flanking sequences for one Jalmenus species
indicated (i) only weak support for the available model of insect 12S rRNA
structure and (ii) that tRNA translocation is a frequent event in the
evolution of insect mitochondrial genomes.
相似文献
3.
Combined monte carlo and molecular dynamics simulation of fully hydrated dioleyl and palmitoyl-oleyl phosphatidylcholine lipid bilayers 总被引:1,自引:1,他引:0
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We have applied a new equilibration procedure for the atomic level simulation of a hydrated lipid bilayer to hydrated bilayers of dioleyl-phosphatidylcholine (DOPC) and palmitoyl-oleyl phosphatidylcholine (POPC). The procedure consists of alternating molecular dynamics trajectory calculations in a constant surface tension and temperature ensemble with configurational bias Monte Carlo moves to different regions of the configuration space of the bilayer in a constant volume and temperature ensemble. The procedure is applied to bilayers of 128 molecules of POPC with 4628 water molecules, and 128 molecules of DOPC with 4825 water molecules. Progress toward equilibration is almost three times as fast in central processing unit (CPU) time compared with a purely molecular dynamics (MD) simulation. Equilibration is complete, as judged by the lack of energy drift in 200-ps runs of continuous MD. After the equilibrium state was reached, as determined by agreement between the simulation volume per lipid molecule with experiment, continuous MD was run in an ensemble in which the lateral area was restrained to fluctuate about a mean value and a pressure of 1 atm applied normal to the bilayer surface. Three separate continuous MD runs, 200 ps in duration each, separated by 10,000 CBMC steps, were carried out for each system. Properties of the systems were calculated and averaged over the three separate runs. Results of the simulations are presented and compared with experimental data and with other recent simulations of POPC and DOPC. Analysis of the hydration environment in the headgroups supports a mechanism by which unsaturation contributes to reduced transition temperatures. In this view, the relatively horizontal orientation of the unsaturated bond increases the area per lipid, resulting in increased water penetration between the headgroups. As a result the headgroup-headgroup interactions are attenuated and shielded, and this contributes to the lowered transition temperature. 相似文献
4.
Loksum Wong Cameron J Weadick Claire Kuo Belinda SW Chang Vincent Tropepe 《BMC developmental biology》2010,10(1):100
Background
The Dmbx1 gene is important for the development of the midbrain and hindbrain, and mouse gene targeting experiments reveal that this gene is required for mediating postnatal and adult feeding behaviours. A single Dmbx1 gene exists in terrestrial vertebrate genomes, while teleost genomes have at least two paralogs. We compared the loss of function of the zebrafish dmbx1a and dmbx1b genes in order to gain insight into the molecular mechanism by which dmbx1 regulates neurogenesis, and to begin to understand why these duplicate genes have been retained in the zebrafish genome. 相似文献5.
6.
Background
The diversity of visual systems in fish has long been of interest for evolutionary biologists and neurophysiologists, and has recently begun to attract the attention of molecular evolutionary geneticists. Several recent studies on the copy number and genomic organization of visual pigment proteins, the opsins, have revealed an increased opsin diversity in fish relative to most vertebrates, brought about through recent instances of opsin duplication and divergence. However, for the subfamily of opsin genes that mediate vision at the long-wavelength end of the spectrum, the LWS opsins, it appears that most fishes possess only one or two loci, a value comparable to most other vertebrates. Here, we characterize the LWS opsins from cDNA of an individual guppy, Poecilia reticulata, a fish that is known exhibit variation in its long-wavelength sensitive visual system, mate preferences and colour patterns.Results
We identified six LWS opsins expressed within a single individual. Phylogenetic analysis revealed that these opsins descend from duplication events both pre-dating and following the divergence of the guppy lineage from that of the bluefin killifish, Lucania goodei, the closest species for which comparable data exists. Numerous amino acid substitutions exist among these different LWS opsins, many at sites known to be important for visual pigment function, including spectral sensitivity and G-protein activation. Likelihood analyses using codon-based models of evolution reveal significant changes in selective constraint along two of the guppy LWS opsin lineages.Conclusion
The guppy displays an unusually high number of LWS opsins compared to other fish, and to vertebrates in general. Observing both substitutions at functionally important sites and the persistence of lineages across species boundaries suggests that these opsins might have functionally different roles, especially with regard to G-protein activation. The reasons why are currently unknown, but may relate to aspects of the guppy's behavioural ecology, in which both male colour patterns and the female mate preferences for these colour patterns experience strong, highly variable selection pressures.7.
Unusual molecular evolution of an Adh pseudogene in Drosophila 总被引:2,自引:0,他引:2
Sullivan DT; Starmer WT; Curtiss SW; Menotti-Raymond M; Yum J 《Molecular biology and evolution》1994,11(3):443-458
8.
Katayose Y Li M Al-Murrani SW Shenolikar S Damuni Z 《The Journal of biological chemistry》2000,275(13):9209-9214
Recombinant I(1)(PP2A) and I(2)(PP2A) did not affect the activity of the catalytic subunit of protein phosphatase 1 (PP1(C)) with (32)P-labeled myelin basic protein, histone H1, and phosphorylase when assayed in the absence of divalent cations. However, in the presence of Mn(2+), I(1)(PP2A) and I(2)(PP2A) stimulated PP1(C) activity by 15-20-fold with myelin basic protein and histone H1 but not phosphorylase. Half-maximal stimulation occurred at 2 and 4 nM I(1)(PP2A) and I(2)(PP2A), respectively. Moreover, I(1)(PP2A) and I(2)(PP2A) reduced the Mn(2+) requirement by about 30-fold to 10 microM. In contrast, PP1(C) activity was unaffected by I(1)(PP2A) and I(2)(PP2A) in the presence of Co(3+) (0.1 mM), Mg(2+) (2 mM), Ca(2+) (0.5 mM), and Zn(2+) (0.1 mM). Following gel filtration chromatography on Sephacryl S-200 in the presence of Mn(2+), PP1(C) coeluted with I(1)(PP2A) and I(2)(PP2A) in the void volume. However, when I(1)(PP2A) and I(2)(PP2A) or Mn(2+) were omitted, PP1(C) emerged with a V(e)/V(0) of approximately 1.6. The results demonstrate that I(1)(PP2A) and I(2)(PP2A) associate with and modify the substrate specificity of PP1(C) in the presence of physiological concentrations of Mn(2+). A novel role is suggested for I(1)(PP2A) and I(2)(PP2A) in the reciprocal regulation of two major mammalian serine/threonine phosphatases, PP1 and PP2A. 相似文献
9.
10.
Denoeud F Roussel M Noel B Wawrzyniak I Da Silva C Diogon M Viscogliosi E Brochier-Armanet C Couloux A Poulain J Segurens B Anthouard V Texier C Blot N Poirier P Ng GC Tan KS Artiguenave F Jaillon O Aury JM Delbac F Wincker P Vivarès CP El Alaoui H 《Genome biology》2011,12(3):R29