Made available in DSpace on 2014-06-11T19:30:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-08Bitstream added on 2014-06-13T21:01:45Z : No. of bitstreams: 1 coan_ai_dr_rcla.pdf: 17033809 bytes, checksum: 1ae8df7113d96a44c82c828cd54a77c3 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The embryology and the seed development of Eriocaulaceae and Cyperaceae were studied here in order to contribute to the taxonomy and phylogeny of both families. The results given by different genera of Eriocaulaceae allowed us to strengthen the embryological uniformity of the family. The endothecial thickenings of the baseplate-type, the spiraperturate pollen grains, the antipodal cyst closely associated to the hypostase, and the operculated endotestal seeds are synapomorphies of Eriocaulaceae within Poales. The use of the character number of microsporangia of anthers in genera delimitation is not consistent, while those related to the seed coat seem to be more stable in establishing relationships between genera. The overall embryological features pointed out the necessity of a taxonomic revision in Eriocaulaceae, aiming at a more natural classification of its taxa. In Cyperaceae, the embryology and the fruit development were investigated in species of Hypolytrum and Rhynchospora, showing that most of these aspects are also uniform within the family. The endothecial thickenings of the spiral type, the Cyperaceous-type of simultaneous microsporogenesis, the trinucleate pollen grain of the pseudomonad type, the formation of a funicular obturator closely associated with the hypostase of the ovule, the Onagrad-Juncus variation embryogeny, and the fruit of the achene type with silica deposition clearly distinguish this family amongst the other Poales. Hypolytrum differs from Rhynchospora as well as from the other genera of Cyperaceae already studied for the spherical pseudomonads, with reticulate exine and central arrangement in the microsporangia, the micropyle formed by both the integuments, and the conspicuous parietal tissue which indicate its position as a basal group in the family. Moreover, the number and the ...(Complete abstract, click electronic address below).

Orientador: Vera Lúcia Scatena / Banca: Marccus Vinícius da Silva Alves / Banca: Simone de Pádua Teixeira / Banca: Silvia Rodrigues Machado / Banca: Julio Antonio Lombardi / Abstract: The embryology and the seed development of Eriocaulaceae and Cyperaceae were studied here in order to contribute to the taxonomy and phylogeny of both families. The results given by different genera of Eriocaulaceae allowed us to strengthen the embryological uniformity of the family. The endothecial thickenings of the baseplate-type, the spiraperturate pollen grains, the antipodal cyst closely associated to the hypostase, and the operculated endotestal seeds are synapomorphies of Eriocaulaceae within Poales. The use of the character number of microsporangia of anthers in genera delimitation is not consistent, while those related to the seed coat seem to be more stable in establishing relationships between genera. The overall embryological features pointed out the necessity of a taxonomic revision in Eriocaulaceae, aiming at a more natural classification of its taxa. In Cyperaceae, the embryology and the fruit development were investigated in species of Hypolytrum and Rhynchospora, showing that most of these aspects are also uniform within the family. The endothecial thickenings of the spiral type, the Cyperaceous-type of simultaneous microsporogenesis, the trinucleate pollen grain of the pseudomonad type, the formation of a funicular obturator closely associated with the hypostase of the ovule, the Onagrad-Juncus variation embryogeny, and the fruit of the achene type with silica deposition clearly distinguish this family amongst the other Poales. Hypolytrum differs from Rhynchospora as well as from the other genera of Cyperaceae already studied for the spherical pseudomonads, with reticulate exine and central arrangement in the microsporangia, the micropyle formed by both the integuments, and the conspicuous parietal tissue which indicate its position as a basal group in the family. Moreover, the number and the ...(Complete abstract, click electronic address below). / Doutor

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-08-15T17:53:44Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) A_Marques_PhD_thesis_2016_FINAL.pdf: 9324057 bytes, checksum: 92c1de27f6fa947d7e6b3e74ae09a849 (MD5) / Made available in DSpace on 2016-08-15T17:53:46Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) A_Marques_PhD_thesis_2016_FINAL.pdf: 9324057 bytes, checksum: 92c1de27f6fa947d7e6b3e74ae09a849 (MD5) Previous issue date: 2015-02-15 / capes / Cromossomos holocêntricos são caracterizados pela ausência de constrição primária e apresentam normalmente a proteína centromérica CENH3 distribuída ao longo de um eixo em cada cromátide. Embora muitos organismos com cromossomos monocêntricos apresentem sequências de DNA centroméricas específicas e associadas com a CENH3, nenhuma sequência centromérica havia sido identificada em organismos com cromossomos holocêntricos até o momento. Além disso, vários estudos reportam adaptações meióticas em espécies com cromossomos holocêntricos. Sendo observada em alguns casos uma inversão da ordem dos eventos meióticos (meiose invertida ou pós-reducional). Assim, o presente trabalho objetivou estudar a organização centromérica e a meiose de espécies com cromossomos holocêntricos do gênero Rhynchospora (Cyperaceae). Foi realizada uma análise citogenômica da organização e composição dos holocentrômeros de Rhynchospora pubera (2n = 10), sendo reportada a primeira descoberta de sequências centroméricas em espécies com cromossomos holocêntricos. Foi observado que os holocentrômeros de R. pubera são compostos principalmente por arranjos de DNA satélite (Tyba) e retroelementos centroméricos (CRRh) distribuídos pelo genoma. A análise detalhada da sucessão dos eventos meióticos de R. pubera e R. tenuis (2n = 4) reportou uma prófase inicial semelhante a de monocêntricos. No entanto, foi verificado que as cromátides-irmãs separam para polos opostos durante a anáfase I e os homólogos segregam somente durante a meiose II, comprovando uma meiose invertida para ambas as espécies. Curiosamente, durante a meiose de R. pubera foi observado uma organização diferencial dos centrômeros. Ao contrário do observado em mitose, durante meiose não foi observado a formação de holocentrômeros em forma de linha, sendo, na verdade, observado estruturas centroméricas aglomeradas. O restabelecimento de holocentrômeros em forma de linha se deu durante a primeira mitose do pólen. / Holocentric chromosomes are characterized by the absence primary constriction and normally show the centromeric protein CENH3 distributed along the axis of each chromatid. Although many monocentric organisms show centromere-specific DNA sequences associated to CENH3, no centromeric sequences had been identified in any holocentric organism so far. Furthermore, many studies report meiotic adaptations in holocentric species. In some cases is observed an inversion of the order of meiotic events. This type of meiosis has been named of inverted or post-reductional meiosis and would be exclusive of holocentric organisms. Thus, the present work aimed to study the centromere organization and meiosis of holocentric species of the genus Rhynchospora (Cyperaceae). A cytogenomic analysis of the composition and organization of the holocentromeres of Rhynchospora pubera (2n = 10) has been performed, being reported the first centromeric sequences from a holocentric species. It was observed that the holocentromeres of R. pubera are composed mainly by arrays of satellite DNA (Tyba) and centromeric retrotransposons (CRRh) distributed genomewide. The detailed analysis of the succession of meiotic events of R. pubera and R. tenuis (2n = 4) demonstrated an early meiotic prophase similar to that of monocentric. However, it was verified that sister chromatids separate to opposite poles during anaphase I, while homologs only segregate at meiosis II. These results prove the inverted meiosis for both species. Curiously, it was observed during meiosis of R. pubera a differential organization of centromere units. In contrast to the observed in mitosis, during meiosis we did not observed the formation of line-like holocentromeres, being in fact observed the formation of cluster-like holocentromeres. The reestablishment of a line-like holocentromere occurred during the first pollen mitosis.