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| Subacius,Sandra Maria Rodrigues; Guimarães,Romeu Cardoso. |
| Evolution of metazoan 5S rRNA sequences was analyzed through base composition and types, location and frequency of clustered bases. Characters from sequences of protostomes did not show regular trends as compared with paleontology dating or organism complexity. Trends of increasing G and C, stronger in G clusters, and decreasing A and U, were detected in deuterostomes, in parallel with evolution of complexity. The multifunctional domain 71-104 was highlighted among conserved stretches. Clusters of C were typical of helices. Those of G were longer, extending from helices into loops or related to bulges, which is suggestive of functional significance. Deuterostomian trends were installed early in the lineage and reached full development in aquatic organisms,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ribosomal RNA; Evolution; Repetitive sites; Deuterostomes; Protostomes. |
| Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572002000300006 |
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| Biggelaar, J.A.M. van den; Edsinger-Gonzales, E.; Schram, F.R.. |
| Recent discoveries in the field of developmental genetics have lead to the resurrection of the old idea, first proposed in the early 19th century, that the dorso-ventral axis of deuterostomes, such as vertebrates, has been inverted during the course of evolution from that noted in protostomes, i.e., what in deuterostomes is dorsal, is in protostomes ventral. However, while attractive in its simplicity, such a suggestion ignores the real events of embryogenesis. During the onset of gastrulation in deuterostomes as well as in protostomes a blastopore is formed with exactly the same embryonic, antero-posterior/dorso-ventral polarity. Subsequent differences in the patterns or morphogenetic movement in gastrulation result in a spatial inversion of this... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Amphistomy; Axis inversion; Deuterostomes; Spiral cleavage; Protostomes; Gastrulation. |
| Ano: 2002 |
URL: http://www.repository.naturalis.nl/record/534350 |
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