共查询到20条相似文献,搜索用时 31 毫秒
1.
Mitochondrial small-subunit (19S) rDNA sequences were obtained from 10 angiosperms to further characterize sequence divergence
levels and structural variation in this molecule. These sequences were derived from seven holoparasitic (nonphotosynthetic)
angiosperms as well as three photosynthetic plants. 19S rRNA is composed of a conservative core region (ca. 1450 nucleotides)
as well as two variable regions (V1 and V7). In pairwise comparisons of photosynthetic angiosperms to Glycine, the core 19S rDNA sequences differed by less than 1.4%, thus supporting the observation that variation in mitochondrial rDNA
is 3–4 times lower than seen in protein coding and rDNA genes of other subcellular organelles. Sequences representing four
distinct lineages of nonasterid holoparasites showed significantly increased numbers of substitutions in their core 19S rDNA
sequences (2.3–7.6%), thus paralleling previous findings that showed accelerated rates in nuclear (18S) and plastid (16S)
rDNA from the same plants. Relative rate tests confirmed the accelerated nucleotide substitution rates in the holoparasites
whereas rates in nonparasitic plants were not significantly increased. Among comparisons of both parasitic and nonparasitic
plants, transversions outnumbered transitions, in many cases more than two to one. The core 19S rRNA is conserved in sequence
and structure among all nonparasitic angiosperms whereas 19S rRNA from members of holoparasitic Balanophoraceae have unique
extensions to the V5 and V6 variable domains. Substitution and insertion/deletion mutations characterized the V1 and V7 regions
of the nonasterid holoparasites. The V7 sequence of one holoparasite (Scybalium) contained repeat motifs. The cause of substitution rate increases in the holoparasites does not appear to be a result of
RNA editing, hence the underlying molecular mechanism remains to be fully documented.
Received: 18 May 1997 / Accepted: 11 July 1997 相似文献
2.
Complete chloroplast 23S rRNA and psbA genes from five peridinin-containing dinoflagellates (Heterocapsa pygmaea, Heterocapsa niei, Heterocapsa rotun-data, Amphidinium carterae, and Protoceratium reticulatum) were amplified by PCR and sequenced; partial sequences were obtained from Thoracosphaera heimii and Scrippsiella trochoidea. Comparison with chloroplast 23S rRNA and psbA genes of other organisms shows that dinoflagellate chloroplast genes are the most divergent and rapidly evolving of all.
Quartet puzzling, maximum likelihood, maximum parsimony, neighbor joining, and LogDet trees were constructed. Intersite rate
variation and invariant sites were allowed for with quartet puzzling and neighbor joining. All psbA and 23S rRNA trees showed peridinin-containing dinoflagellate chloroplasts as monophyletic. In psbA trees they are related to those of chromists and red algae. In 23S rRNA trees, dinoflagellates are always the sisters of
Sporozoa (apicomplexans); maximum likelihood analysis of Heterocapsa triquetra 16S rRNA also groups the dinoflagellate and sporozoan sequences, but the other methods were inconsistent. Thus, dinoflagellate
chloroplasts may actually be related to sporozoan plastids, but the possibility of reproducible long-branch artifacts cannot
be strongly ruled out. The results for all three genes fit the idea that dinoflagellate chloroplasts originated from red algae
by a secondary endosymbiosis, possibly the same one as for chromists and Sporozoa. The marked disagreement between 16S rRNA
trees using different phylogenetic algorithms indicates that this is a rather poor molecule for elucidating overall chloroplast
phylogeny. We discuss possible reasons why both plastid and mitochondrial genomes of alveolates (Dinozoa, Sporozoa and Ciliophora)
have ultra-rapid substitution rates and a proneness to unique genomic rearrangements.
Received: 27 December 1999 / Accepted: 24 March 2000 相似文献
3.
4.
Ana I. Antón Antonio J. Martínez-Murcia Francisco Rodríguez-Valera 《Journal of molecular evolution》1998,47(1):62-72
The ribosomal RNA multigene family in Escherichia coli comprises seven rrn operons of similar, but not identical, sequence. Four operons (rrnC, B, G, and E) contain genes in the 16S–23S intergenic spacer region (ISR) for tRNAGlu-2 and three (rrnA, D, and H) contain genes for tRNAIle-1 and tRNAAla-1B. To increase our understanding of their molecular evolution, we have determined the ISR sequence of the seven operons in
a set of 12 strains from the ECOR collection. Each operon was specifically amplified using polymerase chain reaction primers
designed from genes or open reading frames located upstream of the 16S rRNA genes in E. coli K12. With a single exception (ECOR 40), ISRs containing one or two tRNA genes were found at the same respective loci as those
of strain K12. Intercistronic heterogeneity already found in K12 was representative of most variation among the strains studied
and the location of polymorphic sites was the same. Dispersed nucleotide substitutions were very few but 21 variable sites
were found grouped in a stem-loop, although the secondary structure was conserved. Some regions were found in which a stretch
of nucleotides was substituted in block by one alternative, apparently unrelated, sequence (as illustrated by the known putative
insertion of rsl in K12). Except for substitutions of different sizes and insertions/deletions found in the ISR, the pattern of nucleotide
variation is very similar to that found for the 16S rRNA gene in E. coli. Strains K12 and ECOR 40 showed the highest intercistronic heterogeneity. Most strains showed a strong tendency to homogenization.
Concerted evolution could explain the notorious conservation of this region that is supposed to have low functional restrictions.
Received: 31 July 1997 / Accepted: 17 October 1997 相似文献
5.
Horizontal transfer of genes coding for the photosynthetic reaction centers of purple bacteria 总被引:11,自引:0,他引:11
Kenji V. P. Nagashima Akira Hiraishi Keizo Shimada Katsumi Matsuura 《Journal of molecular evolution》1997,45(2):131-136
Phylogenetic trees were drawn and analyzed based on the nucleotide sequences of the 1.5-kb gene fragment coding for the L
and M subunits of the photochemical reaction center of various purple photosynthetic bacteria. These trees are mostly consistent
with phylogenetic trees based on 16S rRNA and soluble cytochrome c, but differ in some significant details. This inconsistency implies horizontal transfer of the genes that code for the photosynthetic
apparatus in purple bacteria. Possibilities of similar transfers of photosynthesis genes during the evolution of photosynthesis
are discussed especially for the establishment of oxygenic photosynthesis.
Received: 8 July 1996 / Accepted: 12 March 1997 相似文献
6.
Although molecular phylogenetic studies of cyanobacteria on the basis of the 16S rRNA gene sequence have been reported, the
topologies were unstable, especially in the inner branchings. Our analysis of 16S rRNA gene phylogeny by the maximum-likelihood
and neighbor-joining methods combined with rate homogeneous and heterogeneous models revealed seven major evolutionary lineages
of the cyanobacteria, including prochlorophycean organisms. These seven lineages are always stable on any combination of these
methods and models, fundamentally corresponding to phylogenetic relationships based on other genes, e.g., psbA, rbcL, rnpB, rpoC, and tufA. Moreover, although known genotypic and phenotypic characters sometimes appear paralleled in independent lineages, many characters
are not contradictory within each group. Therefore we propose seven evolutionary groups as a working hypothesis for successive
taxonomic reconstruction. New 16S rRNA sequences of five unicellular cyanobacterial strains, PCC 7001, PCC 7003, PCC 73109,
PCC 7117, and PCC 7335 of Synechococcus sp., were determined in this study. Although all these strains have been assigned to ``marine clusters B and C,' they were
separated into three lineages. This suggests that the organisms classified in the genus Synechococcus evolved diversely and should be reclassified in several independent taxonomic units. Moreover, Synechococcus strains and filamentous cyanobacteria make a monophyletic group supported by a comparatively high statistical confidence
value (80 to 100%) in each of the two independent lineages; therefore, these monophylies probably reflect the convergent evolution
of a multicellular organization.
Received: 3 September 1998 / Accepted: 30 November 1998 相似文献
7.
Yuji Inagaki Yasuko Hayashi-Ishimaru Megumi Ehara Ikuo Igarashi Takeshi Ohama 《Journal of molecular evolution》1997,45(3):295-300
The chloroplasts of euglenophytes and dinoflagellates have been suggested to be the vestiges of endosymbiotic algae acquired
during the process of evolution. However, the evolutionary positions of these organisms are still inconclusive, and they have
been tentatively classified as both algae and protozoa. A representative gene of the mitochondrial genome, cytochrome oxidase
subunit I (coxI), was chosen and sequenced to clarify the phylogenetic positions of four dinoflagellates, two euglenophytes and one apicomplexan
protist. This is the first report of mitochondrial DNA sequences for dinoflagellates and euglenophytes. Our COXI tree shows clearly that dinoflagellates are closely linked to apicomplexan parasites but not with algae. Euglenophytes and
algae appear to be only remotely related, with euglenophytes sharing a possible evolutionary link with kinetoplastids. The
COXI tree is in general agreement with the tree based on the nuclear encoded small subunit of ribosomal RNA (SSU rRNA) genes,
but conflicts with that based on plastid genes. These results support the interpretation that chloroplasts present in euglenophytes
and dinoflagellates were captured from algae through endosymbioses, while their mitochondria were inherited from the host
cell. We suggest that dinoflagellates and euglenophytes were originally heterotrophic protists and that their chloroplasts
are remnants of endosymbiotic algae.
Received: 24 March 1997 / Accepted: 21 April 1997 相似文献
8.
A Phylogenetic Assessment of the Eukaryotic Light-Harvesting Antenna Proteins, with Implications for Plastid Evolution 总被引:1,自引:0,他引:1
D.G. Durnford J.A. Deane S. Tan G.I. McFadden E. Gantt B.R. Green 《Journal of molecular evolution》1999,48(1):59-68
The light-harvesting complexes (LHCs) are a superfamily of chlorophyll-binding proteins present in all photosynthetic eukaryotes.
The Lhc genes are nuclear-encoded, yet the pigment–protein complexes are localized to the thylakoid membrane and provide a marker
to follow the evolutionary paths of plastids with different pigmentation. The LHCs are divided into the chlorophyll a/b-binding proteins of the green algae, euglenoids, and higher plants and the chlorophyll a/c-binding proteins of various algal taxa. This work examines the phylogenetic position of the LHCs from three additional taxa:
the rhodophytes, the cryptophytes, and the chlorarachniophytes. Phylogenetic analysis of the LHC sequences provides strong
statistical support for the clustering of the rhodophyte and cryptomonad LHC sequences within the chlorophyll a/c-binding protein lineage, which includes the fucoxanthin–chlorophyll proteins (FCP) of the heterokonts and the intrinsic peridinin–chlorophyll
proteins (iPCP) of the dinoflagellates. These associations suggest that plastids from the heterokonts, haptophytes, cryptomonads,
and the dinoflagellate, Amphidinium, evolved from a red algal-like ancestor. The Chlorarachnion LHC is part of the chlorophyll a/b-binding protein assemblage, consistent with pigmentation, providing further evidence that its plastid evolved from a green
algal secondary endosymbiosis. The Chlorarachnion LHC sequences cluster with the green algal LHCs that are predominantly associated with photosystem II (LHCII). This suggests
that the green algal endosymbiont that evolved into the Chlorarachnion plastid was acquired following the emergence of distinct LHCI and LHCII complexes.
Received: 25 February 1998 / Accepted: 13 May 1998 相似文献
9.
Photosynthetic eukaryotes can, according to features of their chloroplasts, be divided into two major groups: the red and
the green lineage of plastid evolution. To extend the knowledge about the evolution of the red lineage we have sequenced and
analyzed the chloroplast genome (cp-genome) of Cyanidium caldarium RK1, a unicellular red alga (AF022186). The analysis revealed that this genome shows several unusual structural features,
such as a hypothetical hairpin structure in a gene-free region and absence of large repeat units. We provide evidence that
this structural organization of the cp-genome of C. caldarium may be that of the most ancient cp-genome so far described. We also compared the cp-genome of C. caldarium to the other known cp-genomes of the red lineage. The cp-genome of C. caldarium cannot be readily aligned with that of Porphyra purpurea, a multicellular red alga, or Guillardia theta due to a displacement of a region of the cp-genome. The phylogenetic tree reveals that the secondary endosymbiosis, through
which G. theta evolved, took place after the separation of the ancestors of C. caldarium and P. purpurea.
We found several genes unique to the cp-genome of C. caldarium. Five of them seem to be involved in the building of bacterial cell envelopes and may be responsible for the thermotolerance
of the chloroplast of this alga. Two additional genes may play a role in stabilizing the photosynthetic machinery against
salt stress and detoxification of the chloroplast. Thus, these genes may be unique to the cp-genome of C. caldarium and may be required for the endurance of the extreme living conditions of this alga.
Received: 3 June 2000 / Accepted: 18 July 2000 相似文献
10.
M.K. Tan 《Journal of molecular evolution》1997,44(6):637-645
Studies of the distribution of the three group I introns (intron A, intron T, and intron AT) in the 26S rDNA of Gaeumannomyces graminis had suggested that they were transferred to a common ancestor of G. graminis var. avenae and var. tritici after it had branched off from var. graminis. Intron AT and intron A exhibited vertical inheritance and coevolved in concert with their hosts. Intron loss could occur
after its acquisition. Loss of any one of the three introns could occur in var. tritici whereas only loss of intron T had been found in the majority of var. avenae isolates. The existence of isolates of var. tritici and var. avenae with three introns suggested that intron loss could be reversed by intron acquisition and that the whole process is a dynamic
one. This process of intron acquisition and intron loss reached different equilibrium points for different varieties and subgroups,
which explained the irregular distribution of these introns in G. graminis. Each of the three group I introns was more closely related to other intron sequences that share the same insertion point
in the 26S rDNA than to each other. These introns in distantly related organisms appeared to have a common ancestry. This
system had provided a good model for studies on both the lateral transfer and common ancestry of group I introns in the 26S
rRNA genes.
Received: 17 May 1996 / Accepted: 14 January 1997 相似文献
11.
Satoshi Yamagishi Masanao Honda Kazuhiro Eguchi Russel Thorstrom 《Journal of molecular evolution》2001,53(1):39-46
Phylogenetic relationships of the family Vangidae and representatives of several other passeriform families were inferred
from 882 base positions of mitochondrial DNA sequences of 12S and 16S rRNA genes. Results indicated the monophyly of the Vangidae,
which includes the genus Tylas, hitherto often placed in the family Pycnonotidae. Our results also revealed the Malagasy endemic Newtonia, a genus never previously assigned to the Vangidae, to be a member of this family. These results suggest the occurrence of
an extensive in situ radiation of this family within Madagascar, and that the extant high diversity of this family is not the result of multiple
colonizations from outside. The extremely high morphological and ecological diversification of the family seems to have been
enhanced through the use and ultimate occupancy of vacant niches in this island.
Received: 8 September 2000 / Accepted: 13 February 2001 相似文献
12.
D. Hepperle H. Nozaki S. Hohenberger V.A.R. Huss E. Morita L. Krienitz 《Journal of molecular evolution》1998,47(4):420-430
Four genera of the Phacotaceae (Phacotus, Pteromonas, Wislouchiella, Dysmorphococcus), a family of loricated green algal flagellates within the Volvocales, were investigated by means of transmission electron
microscopy and analysis of the nuclear encoded small-subunit ribosomal RNA (18S rRNA) genes and the plastid-encoded rbcL genes.
Additionally, the 18S rDNA of Haematococcus pluvialis and the rbcL sequences of Chlorogonium elongatum, C. euchlorum, Dunaliella parva, Chloromonas serbinowii, Chlamydomonas radiata, and C. tetragama were determined. Analysis of ultrastructural data justified the separation of the Phacotaceae into two groups. Phacotus, Pteromonas, and Wislouchiella generally shared the following characters: egg-shaped protoplasts, a single pyrenoid with planar thylakoid double-lamellae,
three-layered lorica, flagellar channels as part of the central lorica layer, mitochondria located in the central cytoplasm,
lorica development that occurs in mucilaginous zoosporangia that are to be lysed, and no acid-resistant cell walls. Dysmorphococcus was clearly different in each of the characters mentioned. Direct comparison of sequences of Phacotus lenticularis, Pteromonas sp., Pteromonas protracta, and Wislouchiella planctonica revealed DNA sequence homologies of ≥98.0% within the 18S gene and 93.9% within the rbcL gene. D. globosus was quite different from these species, with a maximum of 92.9% homology in the 18S rRNA and ≤86.6% in the rbcL gene. It
showed major similarities to the 18S rDNA of Dunaliella salina, with 95.3%, and to the rbcL sequence of Chlamydomonas tetragama, with 90.3% sequence homology. Additionally, the Phacotaceae sensu stricto exclusively shared 10 (rbcL: 4) characters which were present neither in other Chlamydomonadales nor in Dysmorphococcus globosus. Different phylogenetic analysis methods confirmed the hypothesis that the Phacotaceae are polyphyletic. The Phacotaceae sensu stricto form a stable cluster with affinities to the Dunaliellaes and possibly Haematococcus pluvialis. Dysmorphococcus globosus represented an independent lineage that is possibly related to Chlamydomonas moewusii and C. tetragama.
Received: 9 June 1997 / Accepted: 17 October 1997 相似文献
13.
A 2550-bp portion of the mitochondrial genome of a Demosponge, genus Tetilla, was amplified from whole genomic DNA extract and sequenced. The sequence was found to code for the 3′ end of the 16S rRNA
gene, cytochrome c oxidase subunit II, a lysine tRNA, ATPase subunit 8, and a 5′ portion of ATPase subunit 6. The Porifera cluster distinctly
within the eumetazoan radiation, as a sister group to the Cnidaria. Also, the mitochondrial genetic code of this sponge is
likely identical to that found in the Cnidaria. Both the full COII DNA and protein sequences and a portion of the 16S rRNA
gene were found to possess a striking similarity to published Cnidarian mtDNA sequences, allying the Porifera more closely
to the Cnidaria than to any other metazoan phylum. The gene arrangement, COII—tRNALys—ATP8—ATP6, is observed in many Eumetazoan phyla and is apparently ancestral in the metazoa.
Received: 24 November 1997 / Accepted: 14 September 1998 相似文献
14.
Miyuki Noro Ryuichi Masuda Irena A. Dubrovo Michihiro C. Yoshida Makoto Kato 《Journal of molecular evolution》1998,46(3):314-326
Complete sequences of cytochrome b (1,137 bases) and 12S ribosomal RNA (961 bases) genes in mitochondrial DNA were successfully determined from the woolly mammoth
(Mammuthus primigenius), African elephant (Loxodonta africana), and Asian elephant (Elephas maximus). From these sequence data, phylogenetic relationships among three genera were examined. Molecular phylogenetic trees reconstructed
by the neighbor-joining and the maximum parsimony methods provided an identical topology both for cytochrome b and 12S rRNA genes. These results support the ``Mammuthus-Loxodonta' clade, which is contrary to some previous morphological reports that Mammuthus is more closely related to Elephas than to Loxodonta.
Received: 8 April 1997 / Accepted: 23 July 1997 相似文献
15.
To identify conserved features in the rapidly diverging portions of a well-conserved locus, completely sequenced in Plasmodium falciparum and Plasmodium berghei, a computational method based on recurrence analysis was exploited. At the level of the genomic sequence, in both species,
introns and intergenic sequences—though subject to rapid diversification—do not drift without constraints, but rather coevolve,
in the sense that they maintain not only an AT-rich base composition, but also a consistent use of recurring (AT)
n
tracts. One of the two genes present in the conserved locus encodes a protein that exhibits blocks of high similarity to
the first enzyme in glutathione biosynthesis (γ-glutamylcysteine synthetase) but bears long low-complexity insertions, absent
in other organisms. From an analysis of the aminoacid sequence, different constraints appear to act on the borders and on
the central part of the insertions. Albeit maintaining a strong bias toward hydrophylic residues, central portions diverge
more rapidly than borders, through point mutation and differential presence of entire tracts.
Received: 20 September 1999 / Accepted: 9 February 2000 相似文献
16.
We inferred the incidence of nucleotide conversions in the COI and 16S rRNA mitochondrial genes of members of the Symphyta
and basal Apocrita (Hymenoptera). Character-state reconstructions in both genes suggested that conversions between A and T
(AT transversions) occurred much more frequently than any other type of change, although we cannot wholly discount an underlying
transition bias. Parsimony analysis of COI nucleotide characters did not recover phylogeny; e.g., neither the Tenthredinoidea
nor Apocrita were recovered as monophyletic. However, analysis of COI amino acid characters did recover these relationships,
as well as others based on fossil and morphological evidence. Analysis of 16S rRNA characters also recovered these relationships
providing conversions between A and T were down-weighted. Analysis of the combined data sets gave relatively strong support
for various relationships, suggesting that both data sets supported similar topographies. These data sets, both separately
and combined, suggested that the phytophagous Siricidae were more closely related to the predominantly parasitic Apocrita
than were the ectoparasitic Orussoidea. This suggests that the wasp parasitic lifestyle did not have a single origin, unless
the Siricidae have more recently reverted to phytophagy. Alternatively, parasitism evolved twice independently, once in the
Orussoidea and again in the Apocrita. The latter scenario is supported by the observation that the evolution of parasitism
was accompanied by a tendency for the larvae to develop inside plant tissues. Adaptations that accompanied the movement of
wasps into a confined, wood-boring habitat may have preadapted them to becoming ectoparasitic.
Received: 27 March 1996 / Accepted: 2 August 1996 相似文献
17.
Geneviàve Pont-Kingdon Norichika A. Okada Jane L. Macfarlane C. Timothy Beagley Cristi D. Watkins-Sims Thomas Cavalier-Smith G. Desmond Clark-Walker David R. Wolstenholme 《Journal of molecular evolution》1998,46(4):419-431
The nucleotide sequences of two segments of 6,737 ntp and 258 ntp of the 18.4-kb circular mitochondrial (mt) DNA molecule
of the soft coral Sarcophyton glaucum (phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Alcyonacea) have been determined. The larger segment contains
the 3′ 191 ntp of the gene for subunit 1 of the respiratory chain NADH dehydrogenase (ND1), complete genes for cytochrome
b (Cyt b), ND6, ND3, ND4L, and a bacterial MutS homologue (MSH), and the 5′ terminal 1,124 ntp of the gene for the large subunit rRNA (l-rRNA). These genes are arranged in the order given
and all are transcribed from the same strand of the molecule. The smaller segment contains the 3′ terminal 134 ntp of the
ND4 gene and a complete tRNAf-Met gene, and these genes are transcribed in opposite directions. As in the hexacorallian anthozoan, Metridium senile, the mt-genetic code of S. glaucum is near standard: that is, in contrast to the situation in mt-genetic codes of other invertebrate phyla, AGA and AGG specify
arginine, and ATA specifies isoleucine. However, as appears to be universal for metazoan mt-genetic codes, TGA specifies tryptophan
rather than termination. Also, as in M. senile the mt-tRNAf-Met gene has primary and secondary structural features resembling those of Escherichia coli initiator tRNA, including standard dihydrouridine and TψC loop sequences, and a mismatched nucleotide pair at the top of
the amino-acyl stem. The presence of a mutS gene homologue, which has not been reported to occur in any other known mtDNA, suggests that there is mismatch repair activity
in S. glaucum mitochondria. In support of this, phylogenetic analysis of MutS family protein sequences indicates that the S. glaucum mtMSH protein is more closely related to the nuclear DNA-encoded mitochondrial mismatch repair protein (MSH1) of the yeast
Saccharomyces cerevisiae than to eukaryotic homologues involved in nuclear function, or to bacterial homologues. Regarding the possible origin of
the S. glaucum mtMSH gene, the phylogenetic analysis results, together with comparative base composition considerations, and the absence of an
MSH gene in any other known mtDNA best support the hypothesis that S. glaucum mtDNA acquired the mtMSH gene from nuclear DNA early in the evolution of octocorals. The presence of mismatch repair activity in S. glaucum mitochondria might be expected to influence the rate of evolution of this organism's mtDNA.
Received: 13 January 1997 / Accepted: 23 September 1997 相似文献
18.
The complete nucleotide sequence of the mitochondrial genome was determined for a conger eel, Conger myriaster (Elopomorpha: Anguilliformes), using a PCR-based approach that employs a long PCR technique and many fish-versatile primers.
Although the genome [18,705 base pairs (bp)] contained the same set of 37 mitochondrial genes [two ribosomal RNA (rRNA), 22
transfer RNA (tRNA), and 13 protein-coding genes] as found in other vertebrates, the gene order differed from that recorded
for any other vertebrates. In typical vertebrates, the ND6, tRNAGlu, and tRNAPro genes are located between the ND5 gene and the control region, whereas the former three genes, in C. myriaster, have been translocated to a position between the control region and the tRNAPhe gene that are contiguously located at the 5′ end of the 12S rRNA gene in typical vertebrates. This gene order is similar
to the recently reported gene order in four lineages of birds in that the latter lack the ND6, tRNAGlu, and tRNAPro genes between the ND5 gene and the control region; however, the relative position of the tRNAPro to the ND6–tRNAGlu genes in C. myriaster was different from that in the four birds, which presumably resulted from different patterns of tandem duplication of gene
regions followed by gene deletions in two distantly related groups of organisms. Sequencing of the ND5–cyt b region in 11 other anguilliform species, representing 11 families, plus one outgroup species, revealed that the same gene
order as C. myriaster was shared by another 4 families, belonging to the suborder Congroidei. Although the novel gene orders of four lineages of
birds were indicated to have multiple independent origins, phylogenetic analyses using nucleotide sequences from the mitochondrial
12S rRNA and cyt b genes suggested that the novel gene orders of the five anguilliform families had originated in a single ancestral species.
Received: 13 July 2000 / Accepted: 30 November 2000 相似文献
19.
The Origin of Chlorarachniophyte Plastids, as Inferred from Phylogenetic Comparisons of Amino Acid Sequences of EF-Tu 总被引:4,自引:0,他引:4
Ken-ichiro Ishida Ying Cao Masami Hasegawa Norihiro Okada Yoshiaki Hara 《Journal of molecular evolution》1997,45(6):682-687
A molecular phylogenetic analysis of elongation factor Tu (EF-Tu) proteins from plastids was performed in an attempt to identify
the origin of chlorarachniophyte plastids, which are considered to have evolved from the endosymbiont of a photosynthetic
eukaryote. Partial sequences of the genes for plastid EF-Tu proteins (1,080–1,089 bp) were determined for three algae that
contain chlorophyll b, namely, Gymnochlora stellata (Chlorarachniophyceae), Bryopsis maxima (Ulvophyceae), and Pyramimonas disomata (Prasinophyceae). The deduced amino acid sequences were used to construct phylogenetic trees of the plastid and bacterial
EF-Tu proteins by the maximum likelihood, the maximum parsimony, and the neighbor joining methods.
The trees obtained in the present analysis suggest that all plastids that contain chlorophyll b are monophyletic and that the chlorarachniophyte plastids are closely related to those of the Ulvophyceae. The phylogenetic
trees also suggest that euglenophyte plastids are closely related to prasinophycean plastids. The results indicate that the
chlorarachniophyte plastids evolved from a green algal endosymbiont that was closely related to the Ulvophyceae and that at
least two secondary endosymbiotic events have occurred in the lineage of algae with plastids that contain chlorophyll b.
Received: 10 March 1997 / Accepted: 28 July 1997 相似文献
20.
Birgitta M.H. Winnepenninckx David G. Reid Thierry Backeljau 《Journal of molecular evolution》1998,47(5):586-596
In the past, 18S rRNA sequences have proved to be very useful for tracing ancient divergences but were rarely used for resolving
more recent ones. Moreover, it was suggested that the molecule does not contain useful information to resolve divergences
which took place during less than 40 Myr. The present paper takes littorinid phylogeny as a case study to reevaluate the utility
of the molecule for resolving recent divergences. Two data sets for nine species of the snail family Littorinidae were analyzed,
both separately and combined. One data set comprised 7 new complete 18S rRNA sequences aligned with 2 published littorinid
sequences; the other comprised 12 morphological, 1 biochemical, and 2 18S rRNA secondary structure characters. On the basis
of its ability to confirm generally accepted relationships and the congruence of results derived from the different data sets,
it is concluded that 18S rRNA sequences do contain information to resolve ``rapid' cladogenetic events, provided that they
occurred in the not too distant past. 18S rRNA sequences yielded support for (1) the branching order (L. littorea, (L. obtusata, (L. saxatilis, L. compressa))) and (2) the basal position of L. striata in the Littorina clade.
Received: 6 February 1998 / Accepted: 20 March 1998 相似文献