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Embriologia e desenvolvimento de frutos e sementes de Eriocaulaceae e Cyperaceae (Poales)Coan, Alessandra Ike [UNESP] 08 December 2006 (has links) (PDF)
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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).
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Embriologia e desenvolvimento de frutos e sementes de Eriocaulaceae e Cyperaceae (Poales) /Coan, Alessandra Ike. January 2006 (has links)
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
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Estrutura centromérica e adaptações meióticas em espécies holocêntricas do gênero rhynchospora (cyperaceae)SILVA, André Seco Marques da 15 February 2016 (has links)
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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.
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