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81.
82.
Conserved sequence motifs, alignment, and secondary structure for the third domain of animal 12S rRNA 总被引:17,自引:3,他引:14
Hickson RE; Simon C; Cooper A; Spicer GS; Sullivan J; Penny D 《Molecular biology and evolution》1996,13(1):150-169
Secondary structure models are an important step for aligning sequences,
understanding probabilities of nucleotide substitutions, and evaluating the
reliability of phylogenetic reconstructions. A set of conserved sequence
motifs is derived from comparative sequence analysis of 184 invertebrate
and vertebrate taxa (including many taxa from the same genera, families,
and orders) with reference to a secondary structure model for domain III of
animal mitochondrial small subunit (12S) ribosomal RNA. A template is
presented to assist with secondary structure drawing. Our model is similar
to previous models but is more specific to mitochondrial DNA, fitting both
invertebrate and vertebrate groups, including taxa with markedly different
nucleotide compositions. The second half of the domain III sequence can be
difficult to align precisely, even when secondary structure information is
considered. This is especially true for comparisons of anciently diverged
taxa, but well-conserved motifs assist in determining biologically
meaningful alignments. Patterns of conservation and variability in both
paired and unpaired regions make differential phylogenetic weighting in
terms of "stems" and "loops" unsatisfactory. We emphasize looking carefully
at the sequence data before and during analyses, and advocate the use of
conserved motifs and other secondary structure information for assessing
sequencing fidelity.
相似文献
83.
Evolutionary dynamics of tandem repeats in the mitochondrial DNA control region of the minnow Cyprinella spiloptera 总被引:3,自引:0,他引:3
Length variation due to tandem repeats is now recognized as a common
feature of animal mitochondrial DNA; however, the evolutionary dynamics of
repeated sequences are not well understood. Using phylogenetic analysis,
predictions of three models of repeat evolution were tested for arrays of
260-bp repeats in the cyprinid fish Cyprinella spiloptera. Variation at
different nucleotide positions in individual repeats supported different
models of repeat evolution. One set of characters included several
nucleotide variants found in all copies from a limited number of
individuals, while the other set included an 8- bp deletion found in a
limited number of copies in all individuals. The deletion and an associated
nucleotide change appear to be the result of a deterministic, rather than
stochastic, mutation process. Parallel origins of repeat arrays in
different mitochondrial lineages, possibly coupled with a homogenization
mechanism, best explain the distribution of nucleotide variation.
相似文献
84.
Ixodes (Pholeoixodes) hexagonus, an efficient vector of Borrelia burgdorferi in the laboratory 总被引:2,自引:0,他引:2
LISE GERN LINA N. TOUTOUNGI CHANG MIN HU RE AESCHLIMANN 《Medical and veterinary entomology》1991,5(4):431-435
Borrelia burgdorferi Johnson et al. was first isolated from the midgut of Ixodes dammini Spielman et al. in the U.S.A. and from the midgut of I.ricinus (L.) in Europe. I.ricinus was considered to be the only tick vector of this borrelia, in Europe, until I.hexagonus Leach, the hedgehog tick, was found to harbour spirochaetes. This paper reports an evaluation of the vector competence of I.hexagonus for the spirochaete B.burgdorferi. Transovarial and trans-stadial survival were demonstrated and the spirochaete was transmitted to laboratory mice via the bites of trans-stadially infected I.hexagonus females. 相似文献
85.
LESLIE G. UNDERHILL PETER A. BARTLETT LUKAS BAUMANN ROBERT J.M. CRAWFORD BRUCE M. DYER RE GILDENHUYS DEON C. NEL TERENCE B. OATLEY MEREDITH THORNTON LEISHA UPFOLD ANTHONY J. WILLIAMS PHILIP A. WHITTINGTON ANTON C. WOLFAARDT 《Ibis》1999,141(1):29-37
The bulk ore carrier Apollo Sea sank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersus were oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay. 相似文献
86.
87.
CengizTURE ElifSALKURT 《植物学报(英文版)》2005,47(6):660-667
Airborne pollen grains in the atmosphere of Bozuyuk were investigated over a 2 yr period from 2000 to 2001 using a Durham sampler. A total number of pollen grains of 5 170 pollen grains belonging to 32 taxa were identified and recorded along with some unidentified pollen grains. Of all the pollen grains, 78.66% were arboreal, 19.20% were non-arboreal, and 2.12% were unidentified. The majority of pollen grains investigated were Pinus, Platanus, Quercus, Cupressaceae, Poaceae, Fagus, Salix, Rosaceae, Urticaceae, Asteraceae, and Chenopodiaceae. The maximum number of pollen grains was recorded in May. 相似文献
88.
SOLENN LE CADRE MARIE‐CATHERINE BOISSELIER‐DUBAYLE JOSIE LAMBOURDIRE NATHALIE MACHON JACQUES MORET SARAH SAMADI 《Molecular ecology resources》2005,5(2):358-360
Aconitum napellus is a perennial European Ranunculaceae that is currently decreasing in France. Six polymorphic microsatellite markers were characterized to study the polymorphism among individuals sampled from six populations in France. The total number of alleles per locus varied from two to four. Mean observed heterozygosities at each microsatellite locus ranged from 0.05 to 0.19. This set of microsatellites offers an efficient tool for more detailed investigations on population genetic structure of a rare species that can reproduce both sexually and by vegetative spread. 相似文献
89.
90.