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31.
To understand the evolution of duplicate genes, we compared rates of
nucleotide substitution between 17 pairs of nonallelic duplicated genes in
the tetraploid frog Xenopus laevis with rates between the orthologous loci
of human and rodent. For all duplicated X. laevis genes, the number of
synonymous substitutions per site (dS) was greater than the number of
nonsynonymous substitutions per site (dN), indicating that these genes are
subject to purifying selection. There was also a significant positive
correlation (r = 0.915) between dN for the X. laevis genes and dN for the
mammalian genes, suggesting that, at the amino acid level, the X. laevis
genes and the mammalian genes are under similar constraints. Results of
relative-rate tests showed nearly equal rates of nonsynonymous substitution
in each copy of the X. laevis genes; apparently there are similar
constraints on both copies. No correlation was found between dS for the X.
laevis genes and dS for the mammalian genes. There was a significant
positive correlation both between members of pairs of duplicated X. laevis
genes (r = 0.951) and between human and rodent orthologues (r = 0.854) with
respect to third- position G+C content but no such relationship between the
X. laevis genes and either of their mammalian orthologues. The results
indicate that both copies of a duplicate gene can be subject to purifying
selection and thus support the hypothesis of selection against all
genotypes containing a null allele at either of two duplicate loci.
相似文献
32.
Novel 'homeotic' CMS patterns generated in Nicotiana via cybridization with Hyoscyamus and Scopolia 总被引:1,自引:0,他引:1
Zubko Mikhajlo K.; Zubko Elena I.; Patskovsky Yury V.; Khvedynich Olga A.; Fisahn Joachim; Gleba Yury Yu.; Schieder Otto 《Journal of experimental botany》1996,47(8):1101-1110
Cytoplasmic hybrids (cybrids) that contain nuclear genetic materialfrom Nicotiana tabacum and cytoplasms from Hyoscyamus nigeror Scopolia carniolica were constructed by protoplast fusions.Both types of hybrids exhibited cytoplasmic male sterility (CMS).Furthermore, unusual floral morphogenesis marked by greenflowers deprived of corolla and stamens occurred in themajority of the lines. Backcrosses of these plants with wild-typetobacco demonstrated a maternal inheritance of the greenflower trait. After repeated transfer of cytoplasm (donor-recipientfusion) from cytoplasmic hybrid N. tabacum (+H. niger)to albino plastome mutant N. tabacum DSR A15, male sterile tobaccoplants with two types of flowers were recovered (greenflowers and corolla-containing flowers with transformedstamens). RFLP analysis confirmed that N. tabacum (+ H. niger)and N. tabacum (+S. carniollca) as well as their sexual progeniescontained plastids from H. niger and S. carniolica, respectively.Mitochondrial DNA within the hybrids N. tabacum (+H. niger)originated from H. niger, but was obviously altered. Repeatedparasexual transmission, cybrids in the combination of N. tabacum+N.tabacum (+H. niger), reflected similar characteristics. Cybrids,N. tabacum (+S. carniolica) and their sexual progeny, whichresulted after pollination with wild-type tobacco, containeda modified mtDNA generally originating from tobacco. Furtherhistological analysis established the dramatic difference inthe composition of green flowers and flowers ofwild-type tobacco. Therefore, the construction of tobacco cybridswith foreign cytoplasms provides a functional method for thede nova generation of alternative CMS types. Key words: Nicotiana, Hyoscyamus, Scopolia, cybrids, CMS, homeotic patterns 相似文献
33.
Immunochemical identity of peroxisomal enoyl-CoA hydratase with the peroxisome-proliferation -associated 80,000 mol wt polypeptide in rat liver 总被引:6,自引:1,他引:5
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Peroxisome proliferators, which induce proliferation of hepatic peroxisomes, have been shown previously to cause a marked increase in an 80,000 mol wt polypeptide predominantly in the light mitochondrial and microsomal fractions of liver of rodents. We now present evidence to show that this hepatic peroxisome-proliferation-associated polypeptide, referred to as polypeptide PPA-80, is immunochemically identical with the multifunctional peroxisome protein displaying heat-labile enoyl-CoA hydratase activity. This conclusion is based on the following observations: (a) the purified polypeptide PPA-80 and the heat- labile enoyl-CoA hydratase from livers of rats treated with the peroxisome proliferators Wy-14,643 {[4-chloro-6(2,3-xylidino)-2-pyrimidinylthio]acetic acid} exhibit identical minimum molecular weights of approximately 80,000 on SDS polyacrylamide gel electrophoresis; (b) these two proteins are immunochemically identical on the basis of ouchterlony double diffusion, immunotitration, rocket immunoelectrophoresis, and crossed immunoelectrophoresis analysis; and (c) the immunoprecipitates formed by antibodies to polypeptide PPA-80 when dissociated on a sephadex G-200 column yield enoyl-CoA hydratase activity. Whether the polypeptide PPA-80 exhibits the activity of other enzyme(s) of the peroxisomal β-oxidation system such as fatty acyl-CoA oxidase activity or displays immunochemical identity with such enzymes remains to be determined. The availability of antibodies to polypeptide PPA-80 and enoyl-CoA hydratase facilitated immunofluorescent and immunocytochemical localization of the polypeptide PPA- 80 and enoyl-CoA hydratase in the rat liver. The indirect immunofluorescent studies with these antibodies provided direct visual evidence for the marked induction of polypeptide PPA-80 and enoyl-CoA hydratase in the livers of rats treated with Wy-14,643. The present studies also provide immunocytochemical evidence for the localization of polypeptide PPA- 80 and the heat-labile enoyl-CoA hydratase in the peroxisome, but not in the mitochondria, of hepatic parenchymal cells. These studies, therefore, provide morphological evidence for the existence of fatty acyl-CoA oxidizing system in peroxisomes. An increase of polypeptide PPA-80 on SDS polyacrylamide gel electrophoretic analysis of the subcellular fractions of liver of rodents treated with lipid-lowering drugs should serve as a reliable and sensitive indicator of enhanced peroxisomal β- oxidation system. 相似文献
34.
35.
V. A. Sidorov M. K. Zubko A. A. Kuchko I. K. Komarnitsky Y. Y. Gleba 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,74(3):364-368
Summary Leaf mesophyll protoplasts of Solanum pinnatisectum (2n=24) -irradiated at doses of 200 Gy and consequently unable to divide were fused with untreated protoplasts of genomic chlorophyll deficient mutant IvP 841-1 (2n=24) containing the germplasms of S. tuberosum and S. phureja. Two types of plants differing in their pigmentation characteristics were selected. The regenerants of one group were identified as true somatic hybrids by using isozyme analyses of esterase and aspartate aminotransferase. The anthocyanin marker of S. pinnatisectum was phenotypically expressed in these regenerants and could be used as an additional selection trait for hybrid screening in this species combination. The regenerants of the second group were corrected for the gene controlling chlorophyll deficiency but contained species-specific isozymes of the potato cultivar only. Restriction analysis of chloroplast DNA revealed chloroplasts of the S. pinnatisectum type in all but one of the plants tested. The fusion experiments involving -irradiated protoplasts show that this approach in potato reconstruction has the advantage of producing a wide range of genetically novel plants.Dedicated to Prof. H. F. Linskens on his 65th birthday 相似文献
36.
We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment. 相似文献
37.
Sheran HW Law Rudolf SS Wu Patrick KS Ng Richard MK Yu Richard YC Kong 《BMC molecular biology》2006,7(1):15-13
Background
Hypoxia-inducible factors (HIFs) are involved in adaptive and survival responses to hypoxic stress in mammals. In fish, very little is known about the functions of HIFs. 相似文献38.
39.
Jigme M Sethi Augustine MK Choi William J Calhoun Bill T Ameredes 《Respiratory research》2008,9(1):45
Background
Nitric oxide (NO) and carbon monoxide (CO) in exhaled breath are considered obtainable biomarkers of physiologic mechanisms. Therefore, obtaining their measures simply, non-invasively, and repeatedly, is of interest, and was the purpose of the current study.Methods
Expired NO (ENO) and CO (ECO) were measured non-invasively using a gas micro-analyzer on several strains of mice (C57Bl6, IL-10-/-, A/J, MKK3-/-, JNK1-/-, NOS-2-/- and NOS-3-/-) with and without allergic airway inflammation (AI) induced by ovalbumin systemic sensitization and aerosol challenge, compared using independent-sample t-tests between groups, and repeated measures analysis of variance (ANOVA) within groups over time of inflammation induction. ENO and ECO were also measured in C57Bl6 and IL-10-/- mice, ages 8–58 weeks old, the relationship of which was determined by regression analysis. S-methionyl-L-thiocitrulline (SMTC), and tin protoporphyrin (SnPP) were used to inhibit neuronal/constitutive NOS-1 and heme-oxygenase, respectively, and alter NO and CO production, respectively, as assessed by paired t-tests. Methacholine-associated airway responses (AR) were measured by the enhanced pause method, with comparisons by repeated measures ANOVA and post-hoc testing.Results
ENO was significantly elevated in naïve IL-10-/- (9–14 ppb) and NOS-2-/- (16 ppb) mice as compared to others (average: 5–8 ppb), whereas ECO was significantly higher in naïve A/J, NOS-3-/- (3–4 ppm), and MKK3-/- (4–5 ppm) mice, as compared to others (average: 2.5 ppm). As compared to C57Bl6 mice, AR of IL-10-/-, JNK1-/-, NOS-2-/-, and NOS-3-/- mice were decreased, whereas they were greater for A/J and MKK3-/- mice. SMTC significantly decreased ENO by ~30%, but did not change AR in NOS-2-/- mice. SnPP reduced ECO in C57Bl6 and IL-10-/- mice, and increased AR in NOS-2-/- mice. ENO decreased as a function of age in IL-10-/- mice, remaining unchanged in C57Bl6 mice.Conclusion
These results are consistent with the ideas that: 1) ENO is associated with mouse strain and knockout differences in NO production and AR, 2) alterations of ENO and ECO can be measured non-invasively with induction of allergic AI or inhibition of key gas-producing enzymes, and 3) alterations in AR may be dependent on the relative balance of NO and CO in the airway. 相似文献40.
Biomarkers aid the study of osteoarthritis (OA) in a number of different ways. In this article we summarise briefly their
multiple uses and reflect on how the study reported in a previous edition of Arthritis Research & Therapy should promote further investigation of cartilage oligomeric matrix protein (COMP). COMP is foremost among hitherto investigated
biomarkers and is most consistently shown to predict knee OA progression. Precisely what role it plays in OA pathogenesis
remains unclear and elucidating this may be key to defining, and then targeting, the cellular pathways involved in OA. 相似文献