scholarly journals Cytoplasmic connection of sperm cells to the pollen vegetative cell nucleus: potential roles of the male germ unit revisited

2011 ◽  
Vol 62 (5) ◽  
pp. 1621-1631 ◽  
Author(s):  
A. D. McCue ◽  
M. Cresti ◽  
J. A. Feijo ◽  
R. K. Slotkin
Keyword(s):  
Cell Nucleus ◽  
Vegetative Cell ◽  
Sperm Cells ◽  
Male Germ Unit

scholarly journals Proliferation and cell fate establishment during Arabidopsis male gametogenesis depends on the Retinoblastoma protein

2009 ◽  
Vol 106 (17) ◽  
pp. 7257-7262 ◽  
Author(s):  
Zhong Chen ◽  
Said Hafidh ◽  
Shi Hui Poh ◽  
David Twell ◽  
Frederic Berger
Keyword(s):  
Cell Proliferation ◽  
Germ Cell ◽  
Cell Fate ◽  
Vegetative Cell ◽  
Germ Line ◽  
Sperm Cells ◽  
Cyclin Dependent Kinase ◽  
Rb Protein ◽  
Male Gametogenesis ◽  
Male Germline

The Retinoblastoma (Rb) protein is a conserved repressor of cell proliferation. In animals and plants, deregulation of Rb protein causes hyperproliferation and perturbs cell differentiation to various degrees. However, the primary developmental impact of the loss of Rb protein has remained unclear. In this study we investigated the direct consequences of Rb protein knockout in the Arabidopsis male germline using cytological and molecular markers. The Arabidopsis germ line derives from the unequal division of the microspore, producing a small germ cell and a large terminally differentiated vegetative cell. A single division of the germ cell produces the 2 sperm cells. We observed that the loss of Rb protein does not have a major impact on microspore division but causes limited hyperproliferation of the vegetative cell and, to a lesser degree, of the sperm cells. In addition, cell fate is perturbed in a fraction of Rb-defective vegetative cells. These defects are rescued by preventing cell proliferation arising from down-regulation of cyclin-dependent kinase A1. Our results indicate that hyperproliferation caused by the loss of Rb protein prevents or delays cell determination during plant male gametogenesis, providing further evidence for a direct link between fate determination and cell proliferation.

Development of sperm cells in barley

1975 ◽  
Vol 53 (10) ◽  
pp. 1051-1062 ◽  
Author(s):  
David D. Cass ◽  
Ilana Karas
Keyword(s):  
Cell Membrane ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Grains ◽  
Complete Separation ◽  
Pollen Wall ◽  
Vegetative Nucleus ◽  
Sperm Cells ◽  
Subsequent Stage ◽  
Microspore Stage

Ultrastructural events in barley sperm development were examined from the uninucleate microspore stage to establishment of two mature sperm cells in pollen grains. Microspore mitosis produces a vegetative nucleus and a naked generative cell, both embedded in vegetative cell cytoplasm. The generative cell membrane is enclosed by vegetative cell membrane. The generative cell, at first apparently unattached, becomes attached to the pollen wall and acquires a cell wall by centripetal vesicle accumulation. Wall formation may be complete at the time of generative cell karyokinesis; karyokinesis occurs while the generative cell is attached to the pollen wall. Cytokinesis of the generative cell is delayed. The subsequent stage is a binucleate, attached generative cell with a wall. Generative cell cytokinesis appears to involve formation of a partition between the two sperm nuclei. Eventual complete separation of the sperm cells occurs only after the two-celled derivative of the generative cell detaches from the pollen wall. Final stages in sperm cell separation are considered to result from degradation of the partitioning and surrounding wall, not from furrowing of a naked binucleate generative cell according to previous suggestions. Mature plastids were not observed in the generative cell or the sperms.

Ultrastructure of sperm cells and the male germ unit in pollen tubes ofNicotiana tabacum

PROTOPLASMA ◽  
1989 ◽  
Vol 152 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Hong-Shi Yu ◽  
Shi-Yi Hu ◽  
Cheng Zhu
Keyword(s):  
Pollen Tubes ◽  
Sperm Cells ◽  
Male Germ Unit ◽  
Ofnicotiana Tabacum

Migration of sperm cells during pollen tube elongation in Arabidopsis thaliana: behavior during transport, maturation and upon dissociation of male germ unit associations

Planta ◽  
2010 ◽  
Vol 233 (2) ◽  
pp. 325-332 ◽  
Author(s):  
Lili Ge ◽  
Xiaoping Gou ◽  
Tong Yuan ◽  
Greg W. Strout ◽  
Jin Nakashima ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Sperm Cells ◽  
Male Germ Unit ◽  
Pollen Tube Elongation

scholarly journals Highly expressed maize pollen genes display coordinated expression with neighboring transposable elements and contribute to pollen fitness

2019 ◽  
Author(s):  
Cedar Warman ◽  
Kaushik Panda ◽  
Zuzana Vejlupkova ◽  
Sam Hokin ◽  
Erica Unger-Wallace ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Transposable Elements ◽  
Vegetative Cell ◽  
Sperm Cell ◽  
Transcript Level ◽  
Flowering Plants ◽  
Sperm Cells ◽  
Double Fertilization ◽  
Maize Pollen ◽  
Coordinated Expression

AbstractIn flowering plants, the haploid male gametophyte (pollen) is essential for sperm delivery, double fertilization, and subsequent initiation of seed development. Pollen also undergoes dynamic epigenetic regulation of expression from transposable elements (TEs), but how this process interacts with gene regulation and function is not clearly understood. To identify components of these processes, we quantified transcript levels in four male reproductive stages of maize (tassel primordia, microspores, mature pollen, and isolated sperm cells) via RNA-seq. We found that, in contrast to Arabidopsis TE expression in pollen, TE transcripts in maize accumulate as early as the microspore stage and are also present in sperm cells. Intriguingly, coordinated expression was observed between the most highly expressed protein-coding genes and neighboring TEs, specifically in both mature pollen and sperm cells. To test the hypothesis that such elevated expression correlates with functional relevance, we measured the fitness cost (male-specific transmission defect) of GFP-tagged exon insertion mutations in over 50 genes highly expressed in pollen vegetative cell, sperm cell, or seedling (as a sporophytic control). Insertions in genes highly expressed only in seedling or primarily in sperm cells (with one exception) exhibited no difference from the expected 1:1 transmission ratio. In contrast, insertions in over 20% of vegetative cell genes were associated with significant reductions in fitness, showing a positive correlation of transcript level with non-Mendelian segregation. The gamete expressed2 (gex2) gene was the single sperm cell gene associated with reduced transmission when mutant (<35% for two independent insertions), and also triggered seed defects when crossed as a male, supporting a role for gex2 in double fertilization. Overall, our study demonstrates a developmentally programmed and coordinated transcriptional activation of TEs and genes, and further identifies maize pollen as a model in which transcriptomic data have predictive value for quantitative phenotypes.Author SummaryIn flowering plants, pollen is essential for delivering sperm cells to the egg and central cell for double fertilization, initiating the process of seed development. In plants with abundant pollen like maize, this process can be highly competitive. In an added layer of complexity, growing evidence indicates expression of transposable elements (TEs) is more dynamic in pollen than in other plant tissues. How these elements impact pollen function and gene regulation is not well understood. We used transcriptional profiling to generate a framework for both detailed analysis of TE expression and quantitative assessment of gene function during maize pollen development. TEs are expressed early and persist, many showing coordinate activation with highly-expressed neighboring genes in the pollen vegetative cell and sperm cells. Measuring fitness costs for a set of over 50 mutations indicates a correlation between elevated transcript level and gene function in the vegetative cell. Finally, we establish a role in fertilization for the gamete expressed2 (gex2) gene, identified based on its specific expression in sperm cells. These results highlight maize pollen as a powerful model for investigating the developmental interplay of TEs and genes, as well as for measuring fitness contributions of specific genes.

scholarly journals Intercellular communication in Arabidopsis thaliana pollen discovered via AHG3 transcript movement from the vegetative cell to sperm

2015 ◽  
Vol 112 (43) ◽  
pp. 13378-13383 ◽  
Author(s):  
Hua Jiang ◽  
Jun Yi ◽  
Leonor C. Boavida ◽  
Yuan Chen ◽  
Jörg D. Becker ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Intercellular Communication ◽  
Protein Phosphatase ◽  
Pollen Tube Growth ◽  
Vegetative Cell ◽  
Male Gametophyte ◽  
Pollen Grain ◽  
Sperm Cells ◽  
Coding Region

An Arabidopsis pollen grain (male gametophyte) consists of three cells: the vegetative cell, which forms the pollen tube, and two sperm cells enclosed within the vegetative cell. It is still unclear if there is intercellular communication between the vegetative cell and the sperm cells. Here we show that ABA-hypersensitive germination3 (AHG3), encoding a protein phosphatase, is specifically transcribed in the vegetative cell but predominantly translated in sperm cells. We used a series of deletion constructs and promoter exchanges to document transport of AHG3 transcripts from the vegetative cell to sperm and showed that their transport requires sequences in both the 5′ UTR and the coding region. Thus, in addition its known role in transporting sperm during pollen tube growth, the vegetative cell also contributes transcripts to the sperm cells.

scholarly journals Patterns of DNA synthesis during pollen embryogenesis in henbane.

1977 ◽  
Vol 73 (2) ◽  
pp. 521-526 ◽  
Author(s):  
V Raghavan
Keyword(s):  
Dna Synthesis ◽  
Cell Nucleus ◽  
Vegetative Cell ◽  
Generative Cell ◽  
Pollen Embryogenesis ◽  
Cell Nuclei ◽  
Cell Cycles

Continued DNA synthesis in the generative cell nucleus, followed by mitosis and cytokinesis, results in the formation of pollen embryoids in cultured anthers of H. niger. In contrast, the nucleus of the vegetative cell undergoes no DNA synthesis after it is cut off, or synthesizes DNA only during a limited number of cell cycles. DNA synthetic patterns in the generative and vegetative cell nuclei confirm the ontogeny of embryoids described in this plant.

Ultrastructure of Testicular Spermatozoon of the Fish Oreochromis Niloticus

1988 ◽  
Vol 46 ◽  
pp. 278-279
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Electron Microscope ◽  
Oreochromis Niloticus ◽  
Osmium Tetroxide ◽  
Sperm Cells ◽  
Adult Fish ◽  
Testicular Sperm ◽  
Thin Sections ◽  
Important Fish ◽  
Testicular Spermatozoon ◽  
Diamond Knife

Tilapia, Oreochromis niloticus, is an economically important fish in Saudi Arabia. Elucidation of reproductive biology of this species is necessary for successful breeding program. In this paper we describe fine structure of testicular sperm cells in O, niloticus.Testes from young adult fish were fixed in gluteraldehyde (2%) and osmium tetroxide (1%), both in cacodyl ate buffer. Specimens were processed in the conventional way for electron microscopy and thin sections of tissues (obtained by cutting the blocks with a diamond knife) were stained by ura- nyl acetate and lead citrate. These were examined in a Carl Zeiss electron microscope operated at 40 kV to 60 kV. Sperm cells were obtained from testes by squeezing them in cacodyl ate buffer. They were fixed in gluteraldehyde (2%) in the same buffer, air dried, gold coated and then examined in a Philips scanning electron microscope (SEM) operated at 25kV.The spermatozoon of O. niloticus is consisting of head, midpiece and tail (Fig. 1).

Organization of transcription and pre-mRNA splicing within the mammalian cell nucleus

1995 ◽  
Vol 53 ◽  
pp. 768-769
Author(s):  
D.L. Spector ◽  
S. Huang ◽  
S. Kaurin
Keyword(s):  
Rna Polymerase Ii ◽  
Cell Nucleus ◽  
Functional Organization ◽  
Mrna Splicing ◽  
Splicing Factors ◽  
Interchromatin Granule Clusters ◽  
Interchromatin Granule ◽  
Nuclear Regions ◽  
Relationship Of ◽  
Perichromatin Fibrils

We have been interested in the organization of RNA polymerase II transcription and pre-mRNA splicing within the cell nucleus. Several models have been proposed for the functional organization of RNA within the eukaryotic nucleus and for the relationship of this organization to the distribution of pre-mRNA splicing factors. One model suggests that RNAs which must be spliced are capable of recruiting splicing factors to the sites of transcription from storage and/or reassembly sites. When one examines the organization of splicing factors in the nucleus in comparison to the sites of chromatin it is clear that splicing factors are not localized in coincidence with heterochromatin (Fig. 1). Instead, they are distributed in a speckled pattern which is composed of both perichromatin fibrils and interchromatin granule clusters. The perichromatin fibrils are distributed on the periphery of heterochromatin and on the periphery of interchromatin granule clusters as well as being diffusely distributed throughout the nucleoplasm. These nuclear regions have been previously shown to represent initial sites of incorporation of 3H-uridine.

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