Variations of Nucleolar Ultrastructure in Relation to Transcriptional Activity During G1 S, and G2 Periods of Microspore Interphase

Risueño, María Carmen; Testillano, P. S.; Sánchez-Pina, M. Amelia

doi:10.1007/978-3-642-73271-3_2

Cited by 10 publications

(8 citation statements)

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“…The detection of two peaks of DNA synthesis by ultrastructural PCNA immunolocalization would indicate the existence of three sub-periods in the microspore S-phase, which has not previously been reported, apart from our previous studies using Feulgen staining (Arquiaga 1985; Risueño et al 1985Risueño et al , 1988Testillano and Risueño 1988;Testillano 1991). The first replicative sub-period (S1) would take place at the beginning of interphase, followed by a longer intermediate sub-period (S2) in which DNA synthesis slows down, and a final one (S3) at the end of interphase.…”

Section: Discussionmentioning

confidence: 86%

“…The microspore nucleus is pushed towards the cell wall, making it divide asymmetrically to produce two unequal cells, one vegetative and the other generative, of the bicellular pollen grain. Therefore, the DNA of the microspore nucleus must duplicate at some time before mitosis, but there are no ultrastructural data related to the timing of replication in the different sub-phases of microsporogenesis and only a few reports on defining periods within microspore interphase (Risueño et al 1988;Testillano and Risueño 1988;Testillano 1991;Fadón 1993). The two cells of the bicellular pollen grain fulfil different roles.…”

Section: Introductionmentioning

confidence: 96%

“…Among these, the microspore interphase is a key step. The haploid microspores, produced by meiosis of the pollen mother cells, undergo a series of transformations and activity periods that can be recognized by specific structural features and constitute cellular markers of developmental stages (Risueño et al 1988; Testillano and Risueño 1988;Testillano 1991;Fadón 1993). These changes during microspore interphase mainly involve the formation of a large cytoplasmic vacuole, which sets a polarity that affects future cell development.…”

Section: Introductionmentioning

confidence: 99%

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Immunoelectron microscopy of PCNA as an efficient marker for studying replication times and sites during pollen development

et al. 2000

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Here we report for the first time the ultrastructural localization of DNA replication sites in the nucleus of plant cells and the timing of replication through the pollen developmental programme by proliferating cell nuclear antigen (PCNA) immunogold labelling. Replication sites were identified by labelling with anti-PCNA antibodies in fibrils of the interchromatin region close to the condensed chromatin, defining a perichromatin subdomain in the interchromatin space where DNA replication takes place. The same nuclear structures are decorated by anti-BrdU (5-bromo-2'-deoxyuridine) immunogold after short pulses of BrdU labelling. Double immunogold labelling for PCNA and DNA show colocalization on these perichromatin structures. PCNA immunoelectron microscopy also allows correlation of replicative activity with the dynamics of chromatin condensation. DNA replication was also monitored at different phases during pollen development by PCNA immunoelectron microscopy, revealing two peaks of DNA synthesis, at the beginning (early tetrad), and the end (late vacuolate), of microspore interphase. High-resolution autoradiography after [3H]thymidine incorporation also showed high replicative activity at the same two periods of microspore interphase. In the bicellular pollen grain, PCNA immunogold labelling revealed that DNA replication in the generative cell starts at an intermediate stage of pollen maturation, whereas the vegetative nucleus does not replicate and is arrested in G1. The use of anti-PCNA antibodies at the ultrastructural level is an easier, faster and more feasible method than the detection of in vivo-incorporated nucleotides, especially in plant systems with long cell cycles. PCNA immunogold labelling is, therefore, proposed as an efficient marker for mapping the sites and timing of replication at the electron microscopy level.

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Section: Discussionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Immunoelectron microscopy of PCNA as an efficient marker for studying replication times and sites during pollen development

et al. 2000

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“…The androspore and vegetative nucleus show a great nucleolar activity, linked to the presence of nucleolar vacuoles (Risueño et al 1988). This feature denotes a high ribosomal and transcriptional RNA synthesis and thus, a high proteinous synthesis.…”

Section: Discussionmentioning

confidence: 99%

Storage substances in the androgametogenesis and mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae)

Santos¹,

Mariath²

1999

Rev. bras. Bot.

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-(Storage substances in the androgametogenesis and mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae)). Storage substances such as starch grains, proteins and lipids were studied during the male gametogenesis and in the mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae). There are two cycles of amylogenesis and amylolyse. The first cycle lasts until the vacuolated stage when the starch is hydrolyzed and amorphous proteins are stored inside the single vacuole. The next cycle begins after mitosis with the formation of the vegetative and generative cells. At this point, the young vegetative cell stores many starch grains that are bigger than in the first cycle. During the maturation of the male gametophyte, the starch is hydrolyzed and it is absent in the mature pollen grain. Small lipid droplets surround the young generative cell after the mitosis of the androspore and are dispersed in the vegetative cytoplasm during its maturity. The relationship between the pollen storage substances and the ontogeny of the layers in the sporoderm, formation of the generative cell, and the male germ unit were discussed.RESUMO -(Substâncias de reserva na androgametogênese e grão de pólen maduro de Ilex paraguariensis St. Hil. (Aquifoliaceae)). A presença de substâncias de reserva na forma de grãos de amido, proteínas e lipídios foi analisada durante a gametogênese masculina em Ilex paraguariensis St.Hil. (Aquifoliaceae). Foram encontrados dois ciclos de amilogênese e amilólise. O primeiro estende-se até a fase de andrósporo vacuolado, quando todo o amido presente é hidrolizado e proteínas, na forma amorfa, são estocadas no interior do único vacúolo do andrósporo. O segundo ciclo inicia a partir da formação das células generativa e vegetativa, sendo que esta última estoca grande quantidade de grãos de amido, maiores que os do primeiro ciclo. Todo o amido é hidrolizado durante a maturação do andrófito e a formação da unidade reprodutiva masculina. Gotas lipídicas circundam a célula generativa durante seu englobamento e estão dispersas no citoplasma vegetativo no andrófito maduro. A síntese e degradação de substâncias de reserva podem estar relacionadas com a formação dos estratos da esporoderme e ontogenia do andrófito binucleado.

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“…Meristematic cells in G1, S, G2, mitosis, and cytokinesis were selected from the sections according to previously described morphological criteria (Seguí-Simarro and Staehelin, 2006aStaehelin, , 2006b; Supplemental Table S1): nuclear to cytoplasmic surface area ratio, which progressively decreases from G1 to G2 (Seguí-Simarro and Staehelin, 2006a); nuclear size, which increases as the nuclear genome replicates at the S phase (Jovtchev et al, 2006); architecture of the nucleolus and its different subdomains (dense fibrillar component, fibrillar centers, granular component, and nucleolar vacuoles), which change during the cell cycle (Risueñ o and Medina, 1986;Risueñ o et al, 1988); and cell wall thickness, which progressively increases after the new cell wall is formed (Risueñ o et al, 1968;Seguí-Simarro and Staehelin, 2006a). A prometaphase cell with a discontinuous nuclear envelope and condensed chromosomes was also selected.…”

Section: Em and Serial Section Reconstructionmentioning

confidence: 99%

The Mitochondrial Cycle of Arabidopsis Shoot Apical Meristem and Leaf Primordium Meristematic Cells Is Defined by a Perinuclear Tentaculate/Cage-Like Mitochondrion

2008

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Plant cells exhibit a high rate of mitochondrial DNA (mtDNA) recombination. This implies that before cytokinesis, the different mitochondrial compartments must fuse to allow for mtDNA intermixing. When and how the conditions for mtDNA intermixing are established are largely unknown. We have investigated the cell cycle-dependent changes in mitochondrial architecture in different Arabidopsis (Arabidopsis thaliana) cell types using confocal microscopy, conventional, and threedimensional electron microscopy techniques. Whereas mitochondria of cells from most plant organs are always small and dispersed, shoot apical and leaf primordial meristematic cells contain small, discrete mitochondria in the cell periphery and one large, mitochondrial mass in the perinuclear region. Serial thin-section reconstructions of high-pressure-frozen shoot apical meristem cells demonstrate that during G1 through S phase, the large, central mitochondrion has a tentaculate morphology and wraps around one nuclear pole. In G2, both types of mitochondria double their volume, and the large mitochondrion extends around the nucleus to establish a second sheet-like domain at the opposite nuclear pole. During mitosis, approximately 60% of the smaller mitochondria fuse with the large mitochondrion, whose volume increases to 80% of the total mitochondrial volume, and reorganizes into a cage-like structure encompassing first the mitotic spindle and then the entire cytokinetic apparatus. During cytokinesis, the cage-like mitochondrion divides into two independent tentacular mitochondria from which new, small mitochondria arise by fission. These cell cycle-dependent changes in mitochondrial architecture explain how these meristematic cells can achieve a high rate of mtDNA recombination and ensure the even partitioning of mitochondria between daughter cells.Mitochondria are the principal source of ATP energy in eukaryotic cells. Although they are often portrayed as static, oval or rod-shaped organelles that sometimes exhibit a branched configuration, studies of living cells carried out over the past 30 years have demonstrated that they are among the most plastic organelles of cells in terms of form and distribution (Calvayrac et al

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Variations of Nucleolar Ultrastructure in Relation to Transcriptional Activity During G1 S, and G2 Periods of Microspore Interphase

Cited by 10 publications

References 11 publications

Immunoelectron microscopy of PCNA as an efficient marker for studying replication times and sites during pollen development

Immunoelectron microscopy of PCNA as an efficient marker for studying replication times and sites during pollen development

Storage substances in the androgametogenesis and mature pollen grain of Ilex paraguariensis St. Hil. (Aquifoliaceae)

The Mitochondrial Cycle of Arabidopsis Shoot Apical Meristem and Leaf Primordium Meristematic Cells Is Defined by a Perinuclear Tentaculate/Cage-Like Mitochondrion

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