Ancient Phylogenetic Separation between Pacific and Atlantic Cephalochordates as Revealed by Mitochondrial Genome Analysis

Nohara, Masahiro; Nishida, Mutsumi; Manthacitra, Vipoosit; Nishikawa, Teruaki

doi:10.2108/zsj.21.203

Cited by 31 publications

(13 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The expression of the single AmphiBMP2/4 gene is both Bmp2-and Bmp4-like (56). AmphiBMP2/4 genes have been sequenced from Pacific and Atlantic species that diverged 112 million years ago (60). Amphioxus genes are typically highly polymorphic between individuals within a species (61) and between species (60).…”

Section: Resultsmentioning

confidence: 99%

Conservation of Bmp2 Post-transcriptional Regulatory Mechanisms

Fritz

Liu

Jiang

et al. 2004

Journal of Biological Chemistry

View full text Add to dashboard Cite

Bone morphogenetic protein (BMP) orthologs from diverse species like flies and humans are functionally interchangeable and play key roles in fundamental processes such as dorso-ventral axis formation in metazoans. Because both transcriptional and post-transcriptional mechanisms play central roles in modulating developmental protein levels, we have analyzed the 3-untranslated region (3UTR) of the Bmp 2 gene. This 3UTR is unusually long and is alternatively polyadenylated. Mouse, human, and dog mRNAs are 83-87% identical within this region. A 265-nucleotide sequence, conserved between mammals, birds, frogs, and fish, is present in Bmp2 but not Bmp4. The ability of AmphiBMP2/4, a chordate ortholog to Bmp2 and Bmp4, to align with this sequence suggests that its function may have been lost in Bmp4. Activation of reporter genes by the conserved region acts by a post-transcriptional mechanism. Mouse, human, chick, and zebrafish Bmp2 synthetic RNAs decay rapidly in extracts from cells not expressing Bmp2. In contrast, these RNAs are relatively stable in extracts from Bmp2-expressing cells. Thus, Bmp2 RNA half-lives in vitro correlate with natural Bmp2 mRNA levels. The fact that non-murine RNAs interact appropriately with the mouse decay machinery suggests that the function of these cis-regulatory regions has been conserved for 450 million years since the fish and tetrapod lineages diverged. Overall, our results suggest that the Bmp2 3UTR contains essential regulatory elements that act post-transcriptionally.

show abstract

Section: Resultsmentioning

confidence: 99%

Conservation of Bmp2 Post-transcriptional Regulatory Mechanisms

Fritz

Liu

Jiang

et al. 2004

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…This divergence time correlates with the beginning of the drifting of major land masses from the Pangea (i.e., around 200 Myr; Marzoli et al 1999), suggesting that speciation of these two cephalochordates could have been a consequence of this major geological event. Using a similar molecular clock approach with cytochrome oxidase c subunit I (COI) and cytochrome b genes, the divergence time between these two Atlantic species and the Pacific species (B. belcheri and Branchiostoma malayanum) was estimated to be approximately 100 Myr (Nohara et al 2004). These data strongly suggest that the morphological similarity between different amphioxus species worldwide can only be explained by the absence of morphological changes during the last 100-200 Myr.…”

Section: Introductionmentioning

confidence: 98%

“…Thus, amphioxus congeners are favorable to test whether conserved morphologies are due to conserved developmental expression patterns, or rather that there is evidence of genetic piracy, because they are very similar morphologically (Poss and Boschung 1996), apparently diverged tens of millions of years ago (Cañestro et al 2002;Nohara et al 2004), and have been extensively studied by developmental geneticists (Schubert et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Evidence for stasis and not genetic piracy in developmental expression patterns of Branchiostoma lanceolatum and Branchiostoma floridae, two amphioxus species that have evolved independently over the course of 200 Myr

et al. 2008

View full text Add to dashboard Cite

Cephalochordates, the most basal extant group in the phylum Chordata, are represented chiefly by about 20 species of the genus Branchiostoma, commonly called amphioxus or lancelets. In recent years, insights into the evolutionary origin of the vertebrates have been gained from molecular genetic studies during the development of three of these amphioxus species (Branchiostoma floridae in North America, Branchiostoma lanceolatum in Europe, and Branchiostoma belcheri in East Asia). In spite of an estimated divergence time of 100-200 Myr among these species, all three are remarkably similar morphologically, and students of amphioxus have tacitly assumed that such resemblances arise during ontogeny from nearly identical networks of developmental genes. We felt that this assumption needed to be reexamined because instances are known--even in comparisons of closely related species--where characters seeming homologous on the basis of morphology actually develop under the control of conspicuously divergent genetic programs (a phenomenon termed "genetic piracy"). In the present work, we tested the hypothesis that morphological similarities reflect strict conservation of developmentally important genes' expression patterns in order to assess whether the developmental genetics of different amphioxus species show evidence of genetic piracy. To these ends, we cloned 18 genes implicated in different developmental functions in B. lanceolatum and compared their gene expression patterns with the known expression patterns of their orthologous genes in B. floridae. We show that, for the most part, conservation of gene expression parallels that of morphology in these two species. We also identified some differences in gene expression, likely reflecting experimental sensitivity, with the exception of Pax1/9, which may result from true developmental specificities in each amphioxus species. Our results demonstrate that morphological conservation reflects stasis in developmental gene expression patterns and find no evidence for genetic piracy. Thus, different species of amphioxus appear to be very similar, not only morphologically, but also in the genetic programs directing the development of their structural features. Moreover, we provide the first catalogue of gene expression data for the European species, B. lanceolatum.

show abstract

“…Then a linearized tree was constructed for the remaining sequences according to the NJ tree topology. The divergence time (112 Mya) between B. floridae and B. belcheri was used for time calibration (Nohara et al, 2004). It should be noted that the species B. japonicum here and the amphioxus B. becheri referred by Nohara et al (2004Nohara et al ( , 2005 are actually the same species, namely B. japonicum (Xu et al, 2005;Zhang et al, 2006).…”

Section: Evolutionary Analysismentioning

confidence: 99%