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  • 1
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The taxonomic position and phylogenetic relationships of the Pelobionta, an amitochondriate amoeboflagellate group, are not yet completely settled. To provide more information, we obtained sequences for the large subunit rDNA gene, the gene for translation elongation factor la, and for a large part of the gene encoding translation elongation factor 2 from a representative of this group. Mastigamoeba balamuthi (formerly Phreatamoeba balamuthi). The gene for the large subunit rDNA was unusually large compared to those of other protists, a phenomenon that had previously been observed for the gene encoding the small subunit rDNA. Phylogenetic reconstruction using a maximum likelihood method was performed with these sequences, as well as the gene encoding the small subunit rDNA. When evaluated individually, the M. balamuthi genes for the small and large subunit rDNAs and elongation factor 1α had a most recent common ancestor with either the Mycetozoa (slime molds) or with Entamoeba histolytica. A clade formed by M. balamuthi, E. histolytica, and Mycetozoa was not rejected statistically for any of the sequences. A combined maximum likelihood analysis using 3,935 positions from all molecules suggested that these three taxonomic units form a robust clade. We were unable to resolve the closest group to this clade using the combined analysis. These findings support the notion, which had previously been proposed primarily on cytological evidence, that both M. balamuthi and E. histolytica are closely related to the Mycetozoa and that these three together represent a major eukaryotic lineage.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Blastocystis hominis, a parasite of the human intestine, has recently been positioned within Stramenopiles by the small subunit rRNA phylogeny. To further confirm its phylogenetic position using multiple molecular sequence data, we determined the nucleotide sequences putatively encoding small subunit ribosomal RNA, cytosolic-type 70-kDa heat shock protein, translation elongation factor 2, and the non-catalytic ‘B’ subunit of vacuolar ATPase of B. hominis (HE87–1 strain). Moreover, we determined the translation elongation factor 2 sequence of an apicomplexan parasite, Plasmodium falciparum, that belongs to alveolates. The maximum likelihood analyses of small subunit rRNA and cytosolic-type 70-kDa heat shock protein clearly demonstrated that B. hominis (HE87–1 strain) is positioned within Stramenopiles, being congruent with the previous small subunit rRNA analysis, including the sequences of B. hominis (Nand strain) and a Blastocystis isolate from guinea pig. Although no clear resolution among major eukaryotic groups was obtained by the individual phytogenies based on the four molecules analyzed here, a combined analysis of various molecules, including these, clearly indicated that Blatocystis/stramenopiles are the closest relatives of alveolates.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1442-1984
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Camellia japonica is considered to be pollinated by birds, but to date no studies have clarified the contribution of birds to the seed production and reproductive success of this species. We conducted a pollinator exclusion experiment that showed that fruit set was sixfold greater in flowers visited by birds than in flowers without bird visitation. Field observations revealed that most of the visitations made by birds were of the species Zosterops japonica. Furthermore, the level of fruit set was found to be saturated after only five visitations by Z. japonica. These results demonstrate that Z. japonica is the most effective pollinator of C. japonica. Such a strong relationship between a plant and an omnivorous bird pollinator has rarely been reported in a temperate zone.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1432
    Keywords: Key words: Maximum likelihood — General reversible Markov model — Amino acid substitution — Chloroplast DNA — AA LogDet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Maximum likelihood (ML) phylogenies based on 9,957 amino acid (AA) sites of 45 proteins encoded in the plastid genomes of Cyanophora, a diatom, a rhodophyte (red algae), a euglenophyte, and five land plants are compared with respect to several properties of the data, including between-site rate variation and aberrant amino acid composition in individual species. Neighbor-joining trees from AA LogDet distances and ML analyses are seen to be congruent when site rate variability was taken into account. Four feasible trees are identified in these analyses, one of which is preferred, and one of which is almost excluded by statistical criteria. A transition probability matrix for the general reversible Markov model of amino acid substitutions is estimated from the data, assuming each of these four trees. In all cases, the tree with diatom and rhodophyte as sister taxa was clearly favored. The new transition matrix based on the best tree, called cpREV, takes into account distinct substitution patterns in plastid-encoded proteins and should be useful in future ML inferences using such data. A second rate matrix, called cpREV*, based on a weighted sum of rate matrices from different trees, is also considered.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1432
    Keywords: Key words: Complete mitochondrial DNAs — Mammalian phylogeny — Chiroptera — Flying fox — Monophyly — Divergence time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Complete sequences of mitochondrial DNA (mtDNA) are useful for the reconstruction of phylogenetic trees of mammals and, in particular, for inferring higher-order relationships in mammals. In this study, we determined the complete sequence (16,705 bp) of the mtDNA of a Japanese megabat, the Ryukyu flying fox (Pteropus dasymallus). We analyzed this sequence phylogenetically by comparing it with the complete sequence of mtDNAs of 35 mammals in an effort to reevaluate the enigmatic relationship between Megachiroptera and Microchiroptera and the relationships between them and other mammals. Maximum-likelihood analysis of 12 concatenated mitochondrial proteins from 36 mammals strongly suggested the monophyly of the order Chiroptera and its close relationship to Fereuungulata (Carnivora + Perissodactyla + Cetartiodactyla). We estimated that megabats and microbats diverged approximately 58 MyrBP and discussed the origin and early evolution of Chiroptera based on our findings.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 254 (1975), S. 212-212 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] One of us (M.H.)5 has calculated the potential energy function for the bending of the hydrogen bond O-H-O o o o O-H, using the method of CNDO/2, one of the semi-empirical LCAO MO SCF methods which includes all the valence electrons. We intend to show here that the histograms of Kroon and Kanters3 ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Origins of life and evolution of the biospheres 6 (1975), S. 219-227 
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The entropy of the amino acid sequences coded by DNA is considered as a measure of diversity or variety of proteins, and is taken as a measure of evolution. The DNA or m-RNA sequence is corsidered as a stationary second-order Markov chain composed of four kinds of bases. Because of the biased nature of the genetic code table, increase of entropy of amino acid sequences is possible with biased nucleotide sequence. Thus the biased DNA base composition and the extreme rarity of the base doubletC p G of higher organisms are explained. It is expected that the amino acid composition was highly biased at the days of the origin of the genetic code table, and the more frequent amino acids have tended to get rarer, and the rarer ones more frequent. This tendency is observed in the evolution of hemoglobin, cytochrome C, fibrinopeptide, immunoglobulin and lysozyme, and protein as a whole.
    Type of Medium: Electronic Resource
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