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1.
Repeated sequence sets in mitochondrial DNA molecules of root knot nematodes (Meloidogyne): nucleotide sequences, genome location and potential for host-race identification. 总被引:5,自引:0,他引:5 下载免费PDF全文
R Okimoto H M Chamberlin J L Macfarlane D R Wolstenholme 《Nucleic acids research》1991,19(7):1619-1626
Within a 7 kb segment of the mtDNA molecule of the root knot nematode, Meloidogyne javanica, that lacks standard mitochondrial genes, are three sets of strictly tandemly arranged, direct repeat sequences: approximately 36 copies of a 102 ntp sequence that contains a TaqI site; 11 copies of a 63 ntp sequence, and 5 copies of an 8 ntp sequence. The 7 kb repeat-containing segment is bounded by putative tRNAasp and tRNAf-met genes and the arrangement of sequences within this segment is: the tRNAasp gene; a unique 1,528 ntp segment that contains two highly stable hairpin-forming sequences; the 102 ntp repeat set; the 8 ntp repeat set; a unique 1,068 ntp segment; the 63 ntp repeat set; and the tRNAf-met gene. The nucleotide sequences of the 102 ntp copies and the 63 ntp copies have been conserved among the species examined. Data from Southern hybridization experiments indicate that 102 ntp and 63 ntp repeats occur in the mtDNAs of three, two and two races of M.incognita, M.hapla and M.arenaria, respectively. Nucleotide sequences of the M.incognita Race-3 102 ntp repeat were found to be either identical or highly similar to those of the M.javanica 102 ntp repeat. Differences in migration distance and number of 102 ntp repeat-containing bands seen in Southern hybridization autoradiographs of restriction-digested mtDNAs of M.javanica and the different host races of M.incognita, M.hapla and M.arenaria are sufficient to distinguish the different host races of each species. 相似文献
2.
Examination of living spermatid nuclei of Gryllus domesticus has revealed the presence of the same structures, the X chromosome, the round body and the axial core structures, which have been described from electron microscopic observations. The outer ribbons of the axial core structures and the round body are composed of 100 Å fibres indiscernible from and often continuous with the fibres composing the X chromosome. That the outer ribbons of the axial core structures and the round body are chromosomal is further substantiated by the results of cytochemical examinations of formaldehyde fixed material which show that the axial core structures and the round body contain RNA, DNA and basic protein. Neither acetic acid-ethanol nor cold ethanol fixation preserve the round body and the axial core structures suggesting that a protein may be responsible for maintenance of the central core structure. The central core structures are always found in close association with condensed chromatin in regions where the chromosome elements are about 1000 Å apart, suggesting that the relative state of condensation of the chromatin and the spacial relationship between condensed regions may be two of the chief factors concerned in central core formation. Maintainance of the condensed state of the chromatin, however, may in turn depend upon central core integrity.Herrn Prof. J. Seiler zu seinem 80. Geburtstag gewidmet. 相似文献
3.
A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)). 相似文献
4.
Monique Monnerot Michel Solignac David R. Wolstenholme 《Journal of molecular evolution》1990,30(6):500-508
Summary Restriction sites were compared in the mitochondrial DNA (mtDNA) molecules from representatives of two closely related species of fruit flies: nine strains ofDrosophila teissieri and eight strains ofDrosophila yakuba. Nucleotide diversities amongD. teissieri strains and amongD. yakuba strains were 0.07% and 0.03%, respectively, and the nucleotide distance between the species was 0.22%. Also determined was the nucleotide sequence of a 2305-nucleotide pari (ntp) segment of the mtDNA molecule ofD. teissieri that contains the noncoding adenine+thymine (A+T)-rich region (1091 ntp) as well as the genes for the mitochondrial small-subunit rRNA, tRNAf-met, tRNAgln, and tRNAile, and portions of the ND2 and tRNAval genes. This sequence differs from the corresponding segment of theD. yakuba mtDNA by base substitutions at 0.1% and 0.8% of the positions in the coding and noncoding regions, respectively. The higher divergence due to base substitutions in the A+T-rich region is accompanied by a greater number of insertions/deletions than in the coding regions. From alignment of theD. teissieri A+T-rich sequence with those ofD. yakuba andDrosophila virilis, it appears that the 40% of this sequence that lies adjacent to the tRNAile gene has been highly conserved. Divergence between the entireD. teissieri andD. yakuba mtDNA molecules, estimated from the sequences, was 0.3%; this value is close to the value (0.22%) obtained from the restriction analysis, but 10 times lower than the value estimated from published DNA hybridization results. From consideration of the relationships of mitochondrial nucleotide distance and allozyme genetic distance found among seven species of theDrosophila melanogaster subgroup, the mitochondrial nucleotide distance observed forD. teissieri andD. yakuba is anomalously low in relation to the nuclear genetic distance. 相似文献
5.
The nucleotide sequence of a segment of mtDNA from Rattus norvegiens (rat) which contains the genes for tRNAile, tRNAgl and tRNAf-met has been determined. A detailed comparison has been made between this sequence and the corresponding sequences of mouse, human and bovine mtDNAs with regard to the primary and secondary structure of the tRNA genes, the regions connecting the tRNA genes, and the regions flanking the tRNA genes which code for the carboxyl terminus of URF-1 and the amino terminus of URF-2. No differences were found in the nucleotide sequences of the genes for tRNAile, tRNAgln and tRNAf-met in mtDNAs from three different female lines of rats (SASCO-1, SASCO-2 and Wild-UT) that differ by substitutions of 0.8% to 1.8% of their total nucleotides. 相似文献
6.
The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs. 相似文献
7.
Judy M. Goddard Jeffrey N. Masters Suzan S. Jones William D. Ashworth Jr. David R. Wolstenholme 《Chromosoma》1981,82(5):595-609
The mitochondrial DNA (mtDNA) molecules of different albino, domesticated rats (Rattus norvegicus) of the SASCO colony are of two kinds (SASCO-1 and SASCO-2) in regard to their sensitivity at certain sites to a number of restriction enzymes. MtDNA molecules from Utah wild R. norvegicus (Wild-UT) have sensitivities to restriction enzymes which differ at some sites from either SASCO-1 or SASCO-2 mtDNA molecules. Four single nucleotide differences were found among the HindIII F fragments (169 nucleotides) of SASCO-1, SASCO-2, and Wild-UT mtDNAs. Arguments are presented in favor of the interpretation that each variant nucleotide is the third nucleotide of the codon containing it, and that none of the four differences would result in a difference in the respective amino acid translated.Dedicated to Professor W. Beermann on the occasion of his 60th birthday 相似文献
8.
Radio-enzymic assay of oxo steroids by their reduction with the tritiated form of reduced nicotinamide--adenine dinucleotide. 下载免费PDF全文
A method of analysis is proposed based on the enzyme-catalysed transfer of tritium from [3H]NADH to suitable substrates. Its practicability is demonstrated on the examples of oestrone and progesterone with the respective use of the 3 beta, 17 beta- and 3 alpha, 20 beta-hydroxysteroid oxidoreductase. Specificity is tested by application to the analysis of the plasma of pregnant women and measurement of the 3H/14C ratios on purification of the enzymic reduction products. 相似文献
9.
The compulsory dispute settlement regime included in the 1982 Law of the Sea Convention is recognized as one of the most comprehensive in a modern international convention. Yet, in the recent application of this regime, the question has arisen as to whether the procedural prerequisites associated with the LOS Convention's compulsory dispute settlement mechanism are so arduous as to avoid binding and compulsory jurisdiction in most instances. This article addresses that question by examining, in particular, the reasoning of the Southern Bluefin Tuna arbitration tribunal, which found Article 281 of Section 1 of the LOS Convention to bar jurisdiction to the compulsory dispute settlement mechanism prescribed by the Convention, and offers suggestions as to how states might distinguish or overcome the barriers imposed by the Southern Bluefin Tuna tribunal in future cases. 相似文献
10.
Jeremy Howick Felicity L. Bishop Carl Heneghan Jane Wolstenholme Sarah Stevens F. D. Richard Hobbs George Lewith 《PloS one》2013,8(3)