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41.
The effects of mispair and nonpair correction in hybrid DNA on base ratios (G + C content) and total amounts of DNA 总被引:1,自引:0,他引:1
Base ratios and total DNA amounts can vary substantially between and within
higher taxa and genera, and even within species. Gene conversion is one of
several mechanisms that could cause such changes. For base substitutions,
disparity in conversion direction is accompanied by an equivalent disparity
in base ratio at the heterozygous site. Disparity in the direction of gene
conversion at meiosis is common and can be extreme. For transitions (which
give purine [R]/pyrimidine [Y] mispairs) and for transversions giving
unlike R/R and Y/Y mispairs in hybrid DNA, this disparity could give slow
but systematic changes in G + C percentage. For transversions giving like
R/R and Y/Y mispairs, it could change AT/TA and CG/GC ratios. From the
extent of correction direction disparity, one can deduce properties of
repair enzymes, such as the ability (1) to excise preferentially the purine
from one mispair and the pyrimidine from the other for two different R/Y
mispairs from a single heterozygous site and (2) to excise one base
preferentially from unlike R/R or Y/Y mispairs. Frame-shifts usually show
strong disparity in conversion direction, with preferential cutting of the
nonlooped or the looped-out strand of the nonpair in heterozygous h-DNA.
The opposite directions of disparity for frame-shifts and their intragenic
suppressors as Ascobolus suggest that repair enzymes have a strong,
systematic bias as to which strand is cut. The conversion spectra of
mutations induced with different mutagens suggest that the nonlooped strand
is preferentially cut, so that base additions generally convert to mutant
and deletions generally convert to wild-type forms. Especially in
nonfunctional or noncoding DNA, this could cause a general increase in DNA
amounts. Conversion disparity, selection, mutation, and other processes
interact, affecting rates of change in base ratios and total DNA.
相似文献
42.
M Matsuda A Tazumi S Kagawa T Sekizuka O Murayama JE Moore BC Millar 《BMC veterinary research》2006,2(1):1-4
Background
At present, six accessible sequences of 16S rDNA from Taylorella equigenitalis (T. equigenitalis) are available, whose sequence differences occur at a few nucleotide positions. Thus it is important to determine these sequences from additional strains in other countries, if possible, in order to clarify any anomalies regarding 16S rDNA sequence heterogeneity. Here, we clone and sequence the approximate full-length 16S rDNA from additional strains of T. equigenitalis isolated in Japan, Australia and France and compare these sequences to the existing published sequences.Results
Clarification of any anomalies regarding 16S rDNA sequence heterogeneity of T. equigenitalis was carried out. When cloning, sequencing and comparison of the approximate full-length 16S rDNA from 17 strains of T. equigenitalis isolated in Japan, Australia and France, nucleotide sequence differences were demonstrated at the six loci in the 1,469 nucleotide sequence. Moreover, 12 polymorphic sites occurred among 23 sequences of the 16S rDNA, including the six reference sequences.Conclusion
High sequence similarity (99.5% or more) was observed throughout, except from nucleotide positions 138 to 501 where substitutions and deletions were noted. 相似文献43.
Impact of Extraction Methods on the Detectable Protein Complement of Metaproteomic Analyses of Marine Sediments 下载免费PDF全文
Lars Wöhlbrand Christoph Feenders Jessica Nachbaur Holger Freund Bert Engelen Heinz Wilkes Hans‐Jürgen Brumsack Ralf Rabus 《Proteomics》2017,17(22)
Metaproteomic analysis targets proteins, the catalytic entities in the habitat, thereby providing direct insights into the metabolic activity of the community studied. A major challenge still remaining for metaproteomics is the effective and comprehensive extraction of proteins from environmental samples, due to their high complexity with respect to organismic diversity and abundance range. Moreover, in certain habitats, the inherent matrix may interfere with protein extraction. In recent years, several studies reported different protein extraction methods for soils known for their complex geochemistry, but only three analyzed marine sediments that generally comprise different though similarly complex geochemistry. In this study, the impact of four different extraction methods was investigated for coastal North Sea and deep sea Pacific Ocean sediments. The extraction methods comprised (i) phenol, (ii) SDS, (iii) a mixture of SDS and phenol, and (iv) urea and thiourea. Prior to extraction, a cell and protein standard (CPS) was added to the sediment samples to trace recovery of proteins from different subcellular locations as well as dissolved BSA. While each extraction method detected distinct peptide complements, SDS‐phenol extraction generally achieved highest protein yield and most comprehensive CPS protein identification. Application of two different methods was shown to further improve proteome coverage. 相似文献
44.
Sofie De Cooman Nathalie De Mey Bram BC Dewulf Rik Carette Thierry Deloof Maurice Sosnowski Andre M De Wolf Jan FA Hendrickx 《BMC anesthesiology》2008,8(1):1-6
Background
Current analgesics have drawbacks such as delays in acquisition, lag-times for effect, and side effects. We recently presented a preliminary report of a new analgesic method involving a two-minute sciatic nerve press, which resulted in immediate short-term relief of pain associated with dental and renal diseases. The present study investigated whether this technique was effective for pain associated with other disease types, and whether the relief was effective for up to one hour.Methods
This randomized, placebo-controlled, parallel-group trial was conducted in four hospitals in Anhui Province, China. Patients with pain were sequentially recruited by participating physicians during clinic visits, and 135 patients aged 15 – 80 years were enrolled. Dental disease patients included those with acute pulpitis and periapical abscesses. Renal disease patients included those with kidney infections and/or stones. Tumor patients included those with nose, breast, stomach and liver cancers, while Emergency Room patients had various pathologies. Patients were randomly assigned to receive a "sciatic nerve press" in which pressure was applied simultaneously to the sciatic nerves at the back of both thighs, or a "placebo press" in which pressure was applied to a parallel region on the front of the thighs. Each fist applied a pressure of 11 – 20 kg for 2 minutes. Patients rated their level of pain before and after the procedure.Results
The "sciatic nerve press" produced immediate relief of pain in all patient groups. Emergency patients reported a 43.5% reduction in pain (p < 0.001). Significant pain relief for dental, renal and tumor patients lasted for 60 minutes (p < 0.001). The peak pain relief occurred at the 10 – 20th minutes, and the relief decreased 47% by the 60th minutes.Conclusion
Two minutes of pressure on both sciatic nerves produced immediate significant short-term conduction analgesia. This technique is a convenient, safe and powerful method for the short-term treatment of clinical pain associated with a diverse range of pathologies.Trial registration
Current Controlled Trials ACTRN012606000439549 相似文献45.
Mark C. Wilkes Kevin Jung Britney E. Lee Mallika Saxena Ryan S. Sathianathen Jacqueline D. Mercado Cristina Perez Johan Flygare Anupama Narla Bertil Glader Kathleen M. Sakamoto 《The Journal of biological chemistry》2021,297(3)
Nemo-like kinase (NLK) is a member of the mitogen-activated protein kinase family of kinases and shares a highly conserved kinase domain with other mitogen-activated protein kinase family members. The activation of NLK contributes to the pathogenesis of Diamond–Blackfan anemia (DBA), reducing c-myb expression and mechanistic target of rapamycin activity, and is therefore a potential therapeutic target. Unlike other anemias, the hematopoietic effects of DBA are largely restricted to the erythroid lineage. Mutations in ribosomal genes induce ribosomal insufficiency and reduced protein translation, dramatically impacting early erythropoiesis in the bone marrow of patients with DBA. We sought to identify compounds that suppress NLK and increases erythropoiesis in ribosomal insufficiency. We report that the active component of ginseng, ginsenoside Rb1, suppresses NLK expression and improves erythropoiesis in in vitro models of DBA. Ginsenoside Rb1–mediated suppression of NLK occurs through the upregulation of miR-208, which binds to the 3′-UTR of NLK mRNA and targets it for degradation. We also compare ginsenoside Rb1–mediated upregulation of miR-208 with metformin-mediated upregulation of miR-26. We conclude that targeting NLK expression through miRNA binding of the unique 3′-UTR is a viable alternative to the challenges of developing small-molecule inhibitors to target the highly conserved kinase domain of this specific kinase. 相似文献
46.
47.
48.
Shaham Beg Rohan Bareja Kentaro Ohara Kenneth Wha Eng David C. Wilkes David J. Pisapia Wael Al Zoughbi Sarah Kudman Wei Zhang Rema Rao Jyothi Manohar Troy Kane Michael Sigouros Jenny Zhaoying Xiang Francesca Khani Brian D. Robinson Bishoy M. Faltas Cora N. Sternberg Andrea Sboner Himisha Beltran Olivier Elemento Juan Miguel Mosquera 《Translational oncology》2021,14(1)
49.
Peter W. Schiller Ralf Schmidt Grazyna Weltrowska Irena Berezowska Thi M.-D. Nguyen Sébastien Dupuis Nga N. Chung Carole Lemieux Brian C. Wilkes Katharine A. Carpenter 《Letters in Peptide Science》1998,5(2-3):209-214
Novel conformationally constrained opioid peptide analogs with antagonist, mixed agonist/ antagonist or agonist properties were developed. TIP(P)-related antagonists showed unprecedented antagonist potency and receptor selectivity, and may have potential for use in analgesia in combination with agonists. A definitive model of their receptor-bound conformation was developed. Three prototype mixed agonist/ antagonists were discovered. They represent the only known compounds with this pharmacological profile and, as expected, one of them was shown to be a potent analgesic and to produce no dependence and less tolerance than morphine. Novel dipeptide derivatives turned out to be potent and selective agonists. Because of their low molecular weight and lipophilic character, these compounds may cross the blood-brain barrier and, thus, may have potential as centrally acting analgesics. 相似文献
50.
Chapman J Miles PD Ofrecio JM Neels JG Yu JG Resnik JL Wilkes J Talukdar S Thapar D Johnson K Sears DD 《PloS one》2010,5(11):e13959