RESUMO
Pollen descriptions, based on LM and SEM observations, are provided for the Pentas complex, an African alliance within the Hedyotideae-Spermacoceae alliance, which includes the genera Pentas, Otomeria, Batopedina, Parapentas, and Chamaepentas. The close relationship among these genera is confirmed by pollen morphological data. The observed variation in pollen character states agrees well with the existing genera and subgenera. The combination of small spheroidal pollen grains with narrow, acute endocolpi, and a small apocolpium index distinguishes Batopedina from Otomeria and Pentas. Parapentas differs from Batopedina in having broad endocolpi with vague ends.Two of the three subgenera of Otomeria, Neotomeria and Volubilis, are supported by pollen data. Pollen of the subgenus Otomeria, however, is less differentiated and is similar to pollen of Pentas subgenus Pentas. The exact relationship between the genera Otomeria and Pentas remains unclear, and molecular data are needed to interpret the observed morphological variation. Chamaepentas has pollen that is nearly identical to that of the Pentas subgenus Chamaepentadoides and of the subgenus Megapentas, i.e. large spheroidal pollen grains with three, medium-length colpi and endocolpi with acute ends. Pollen morphology provides additional support for a close affinity between Pentas subgenus Phyllopentas and Pentas subgenus Vignaldiopsis.
RESUMO
The Antwerp database on large subunit ribosomal RNA now contains 607 complete or nearly complete aligned sequences. The alignment incorporates secondary structure information for each sequence. Other information about the sequences, such as literature references, accession numbers and taxonomic information is also available. Information from the database can be downloaded or searched on the rRNA WWW Server at URL http://rrna.uia.ac.be/
Assuntos
Bases de Dados Factuais , RNA Ribossômico/química , Animais , Bélgica , Classificação , Eucariotos/classificação , Eucariotos/genética , Fungos/classificação , Fungos/genética , Armazenamento e Recuperação da Informação , Internet , Conformação de Ácido Nucleico , Plantas/classificação , Plantas/genética , RNA Ribossômico/genética , Alinhamento de SequênciaRESUMO
Over 11 500 complete or nearly complete sequences are now available from the Antwerp database on small subunit ribosomal RNA. All these sequences are aligned with one another on the basis of the adopted secondary structure model, which is corroborated by the observation of compensating substitutions in the alignment. Literature references, accession numbers and taxonomic information are also compiled. The database can be consulted via the World Wide Web at URL http://rrna.uia.ac.be/ssu/
