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11.
Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae 总被引:10,自引:2,他引:8
Arginine decarboxylase (ADC) is an important enzyme in the production of
putrescine and polyamines in plants. It is encoded by a single or low-copy
nuclear gene that lacks introns in sequences studied to date. The rate of
Adc amino acid sequence evolution is similar to that of ndhF for the
angiosperm family studied. Highly conserved regions provide several target
sites for PCR priming and sequencing and aid in nucleotide and amino acid
sequence alignment across a range of taxonomic levels, while a variable
region provides an increased number of potentially informative characters
relative to ndhF for the taxa surveyed. The utility of the Adc gene in
plant molecular systematic studies is demonstrated by analysis of its
partial nucleotide sequences obtained from 13 representatives of
Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order
Capparales) and 1 from the related order Malvales. Two copies of the Adc
gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied
to data except the basal genus Aethionema. The resulting Adc gene tree
provides robust phylogenetic data regarding relationships within the
complex mustard family, as well as independent support for proposed tribal
realignments based on other molecular data sets such as those from
chloroplast DNA.
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12.
The effects of ammonium in a chemically defined maturation medium on oocyte nuclear maturation and subsequent embryonic development of pigs after in vitro fertilization (IVF) and parthenogenetic activation (PA) were examined. Cumulus–oocyte complexes were matured in Purdue Porcine Medium (PPM) supplemented with 0 mM, 0.02 mM, 0.2 mM, 2 mM, or 20 mM ammonium chloride, or TCM199 with 10% porcine follicle fluid (TCM + pFF; positive control) at 38.7 °C in 7% CO2 in air for 40–44 h. No significant difference (P > 0.05) in nuclear maturation was found between oocytes matured in TCM + pFF or PPM with 0 mM, 0.02 mM and 0.2 mM ammonium chloride. However, nuclear maturation was decreased (P < 0.05) in oocytes matured in PPM with 2 mM or 20 mM ammonium. After IVF, oocytes matured in PPM with 20 mM ammonium resulted in embryos with reduced (P < 0.05) embryonic cleavage and blastocyst development than all other treatment groups. After PA, oocytes matured in PPM with 20 mM ammonium resulted in embryos with lesser (P < 0.05) embryonic cleavage compared to TCM + pFF. However, PA embryos derived from oocytes matured in PPM with both 2 mM and 20 mM ammonium had reduced (P < 0.05) blastocyst development compared with TCM + pFF. These results demonstrate the detrimental effect of ammonium during in vitro oocyte maturation on nuclear progression to metaphase II. Additionally, the presence of ammonium during in vitro maturation negatively influences subsequent embryonic development, although PA embryos appear to be more sensitive to the negative effects of ammonium during oocyte maturation than do IVF embryos. 相似文献
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VLJ Whitehall TD Dumenil DM McKeone CE Bond ML Bettington RL Buttenshaw L Bowdler GW Montgomery LF Wockner BA Leggett 《Epigenetics》2014,9(11):1454-1460
The CpG Island Methylator Phenotype (CIMP) is fundamental to an important subset of colorectal cancer; however, its cause is unknown. CIMP is associated with microsatellite instability but is also found in BRAF mutant microsatellite stable cancers that are associated with poor prognosis. The isocitrate dehydrogenase 1 (IDH1) gene causes CIMP in glioma due to an activating mutation that produces the 2-hydroxyglutarate oncometabolite. We therefore examined IDH1 alteration as a potential cause of CIMP in colorectal cancer. The IDH1 mutational hotspot was screened in 86 CIMP-positive and 80 CIMP-negative cancers. The entire coding sequence was examined in 81 CIMP-positive colorectal cancers. Forty-seven cancers varying by CIMP-status and IDH1 mutation status were examined using Illumina 450K DNA methylation microarrays. The R132C IDH1 mutation was detected in 4/166 cancers. All IDH1 mutations were in CIMP cancers that were BRAF mutant and microsatellite stable (4/45, 8.9%). Unsupervised hierarchical cluster analysis identified an IDH1 mutation-like methylation signature in approximately half of the CIMP-positive cancers. IDH1 mutation appears to cause CIMP in a small proportion of BRAF mutant, microsatellite stable colorectal cancers. This study provides a precedent that a single gene mutation may cause CIMP in colorectal cancer, and that this will be associated with a specific epigenetic signature and clinicopathological features. 相似文献
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Evolution of eutherian cytochrome c oxidase subunit II: heterogeneous rates of protein evolution and altered interaction with cytochrome c 总被引:3,自引:1,他引:2
Cytochrome c oxidase subunit II (COII), encoded by the mitochondrial
genome, exhibits one of the most heterogeneous rates of amino acid
replacement among placental mammals. Moreover, it has been demonstrated
that cytochrome c oxidase has undergone a structural change in higher
primates which has altered its physical interaction with cytochrome c. We
collected a large data set of COII sequences from several orders of mammals
with emphasis on primates, rodents, and artiodactyls. Using phylogenetic
hypotheses based on data independent of the COII gene, we demonstrated that
an increased number of amino acid replacements are concentrated among
higher primates. Incorporating approximate divergence dates derived from
the fossil record, we find that most of the change occurred independently
along the New World monkey lineage and in a rapid burst before apes and Old
World monkeys diverged. There is some evidence that Old World monkeys have
undergone a faster rate of nonsynonymous substitution than have apes. Rates
of substitution at four-fold degenerate sites in primates are relatively
homogeneous, indicating that the rate heterogeneity is restricted to
nondegenerate sites. Excluding the rate acceleration mentioned above,
primates, rodents, and artiodactyls have remarkably similar nonsynonymous
replacement rates. A different pattern is observed for transversions at
four-fold degenerate sites, for which rodents exhibit a higher rate of
replacement than do primates and artiodactyls. Finally, we hypothesize
specific amino acid replacements which may account for much of the
structural difference in cytochrome c oxidase between higher primates and
other mammals.
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20.
Effects of EDTA treatment upon the protein subunit composition and mechanical properties of mammalian single skeletal muscle fibers 总被引:9,自引:0,他引:9
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Considerable interest has been focused on the role of myosin light chain LC(2) in the contraction of vertebrate striated muscle. A study was undertaken to further our investigations (Moss, R.L., G.G. Giulian, and M.L. Greaser, 1981, J. Biol. Chem., 257:8588-8591) of the effects of LC(2) removal upon contraction in skinned fibers from rabbit psoas muscles. Isometric tension and maximum velocity of shortening, V(max), were measured in fiber segments prior to LC(2) removal. The segments were then bathed at 30 degrees C for up to 240 min in a buffer solution containing 20 mM EDTA in order to extract up to 60 percent of the LC(2). Troponin C (TnC) was also partially removed by this procedure. Mechanical measurements were done following the EDTA extraction and the readditions of first TnC and then LC(2) to the segments. The protein subunit compositions of the same fiber segments were determined following each of these procedures by SDS PAGE of small pieces of the fiber. V(max) was found to decrease as the LC(2) content of the fiber segments was reduced by increasing the duration of extraction. EDTA treatment also resulted in substantial reductions in tension due mainly to the loss of TnC, though smaller reductions due to the extraction of LC(2) were also observed. Reversal of the order of recombination of LC(2) and TnC indicated that the reduction in V(max) following EDTA treatment was a specific effect of LC(2) removal. These results strongly suggest that LC(2) may have roles in determining the kinetics and extent of interaction between myosin and actin. 相似文献