scholarly journals An F-Actin Mega-Cable Is Associated With the Migration of the Sperm Nucleus During the Fertilization of the Polarity-Inverted Central Cell of Agave inaequidens

2021 ◽  
Vol 12 ◽  
Author(s):  
Alejandra G. González-Gutiérrez ◽  
Antonia Gutiérrez-Mora ◽  
Jorge Verdín ◽  
Benjamín Rodríguez-Garay
Keyword(s):  
Cell Nucleus ◽  
Short Range ◽  
Sperm Nucleus ◽  
Central Cell ◽  
Actin Dynamics ◽  
Egg Cell ◽  
Double Fertilization ◽  
Long Distance ◽  
Actin Cables ◽  
In Transit

Asparagaceae’s large embryo sacs display a central cell nucleus polarized toward the chalaza, which means the sperm nucleus that fuses with it during double fertilization migrates an atypical long distance before karyogamy. Because of the size and inverted polarity of the central cell in Asparagaceae, we hypothesize that the second fertilization process is supported by an F-actin machinery different from the short-range F-actin structures observed in Arabidopsis and other plant models. Here, we analyzed the F-actin dynamics of Agave inaequidens, a classical Asparagaceae, before, during, and after the central cell fertilization. Several parallel F-actin cables, spanning from the central cell nucleus to the micropylar pole, and enclosing the vacuole, were observed. As fertilization progressed, a thick F-actin mega-cable traversing the vacuole appeared, connecting the central cell nucleus with the micropylar pole near the egg cell. This mega-cable wrapped the sperm nucleus in transit to fuse with the central cell nucleus. Once karyogamy finished, and the endosperm started to develop, the mega-cable disassembled, but new F-actin structures formed. These observations suggest that Asparagaceae, and probably other plant species with similar embryo sacs, evolved an F-actin machinery specifically adapted to support the migration of the fertilizing sperm nucleus within a large-sized and polarity-inverted central cell.

scholarly journals An F-actin mega-cable supports the migration of the sperm nucleus during the fertilization of the polarity-inverted central cell of Agave inaequidens

2021 ◽  
Author(s):  
Alejandra G Gonzalez-Gutierrez ◽  
Antonia Gutierrez-Mora ◽  
Jorge Verdin ◽  
Benjamin Rodriguez-Garay
Keyword(s):  
Cell Nucleus ◽  
Sperm Nucleus ◽  
Endosperm Development ◽  
Central Cell ◽  
Actin Dynamics ◽  
Egg Cell ◽  
Double Fertilization ◽  
Long Distance ◽  
Actin Cables ◽  
In Transit

Asparagaceae's large embryo sacs display a central cell nucleus polarized toward the chalaza, which means the sperm nucleus that fuses it during double fertilization migrates a long distance before karyogamy. Because of the size and inverted polarity of the central cell in Asparagaceae, we hypothesize that the second fertilization process is supported by F-actin structures different from the short-range aster-like ones observed in Arabidopsis. Here, we analyzed the F-actin dynamics of Agave inaequidens, a typical Asparagaceae, before, during, and after central cell fertilization. Several parallel F-actin cables emerging from the nucleus within the central cell, enclosing the vacuole, and reaching the micropylar pole were observed. As fertilization progressed, a thick F-actin mega-cable traversing the vacuole appeared, connecting the central cell nucleus with the micropylar pole near the egg cell. This mega-cable wrapped the sperm nucleus in transit to fuse the central cell one. Once karyogamy finished, the mega-cable disassembled, but new F-actin structures formed during the endosperm development. These observations suggest that Asparagaceae, and probably other plant species with similar embryo sacs, evolved an F-actin machinery specifically adapted to support the migration of the fertilizing sperm nucleus within a large-sized and polarity-inverted central cell.

scholarly journals Cytochemical study of the embryo sac of Nicotiana tabacum L.

2014 ◽  
Vol 50 (1-2) ◽  
pp. 121-125
Author(s):  
V. P. Babbikova ◽  
O. A. Khvendynich ◽  
L. S. Serdyuk
Keyword(s):  
Cell Nucleus ◽  
Mitotic Cycle ◽  
Cell Formation ◽  
Embryo Sac ◽  
Central Cell ◽  
Egg Cell ◽  
Cell Nuclei ◽  
Cytochemical Study ◽  
Male Gametes ◽  
S Period

The mitotic cycle in the egg cell and physico-chemical state of chromatin in the egg cell and central cell of the tobacco embryo sac were studied. It was revealed that during egg cell formation a change in the mitotic cycle kinetics takes place, it consists in prolongation of the S-period as compared with that of somatic cells and G1 - period as compared with that of male gametes. Egg cell and central cell nuclei differ in chromatin structure. Condensed chromatin dominates in the egg cell nucleus, diffuse chromatin in the central cell nucleus, but both show only weak metabolic activity.

scholarly journals Polyspermy Block in the Central Cell During Double Fertilization of Arabidopsis thaliana

2021 ◽  
Vol 11 ◽  
Author(s):  
Shiori Nagahara ◽  
Hidenori Takeuchi ◽  
Tetsuya Higashiyama
Keyword(s):  
Arabidopsis Thaliana ◽  
Sperm Cell ◽  
Central Cell ◽  
Egg Cell ◽  
Sperm Cells ◽  
Potential Contribution ◽  
Double Fertilization ◽  
Male Gametes ◽  
One To One ◽  
The One

During double fertilization in angiosperms, two male gametes (sperm cells), are released from a pollen tube into the receptive region between two female gametes; the egg cell and the central cell of the ovule. The sperm cells fertilize the egg cell and the central cell in a one-to-one manner to yield a zygote and an endosperm, respectively. The one-to-one distribution of the sperm cells to the two female gametes is strictly regulated, possibly via communication among the four gametes. Polyspermy block is the mechanism by which fertilized female gametes prevent fertilization by a secondary sperm cell, and has been suggested to operate in the egg cell rather than the central cell. However, whether the central cell also has the ability to avoid polyspermy during double fertilization remains unclear. Here, we assessed the one-to-one fertilization mechanism of the central cell by laser irradiation of the female gametes and live cell imaging of the fertilization process in Arabidopsis thaliana. We successfully disrupted an egg cell within the ovules by irradiation using a femtosecond pulse laser. In the egg-disrupted ovules, the central cell predominantly showed single fertilization by one sperm cell, suggesting that neither the egg cell nor its fusion with one sperm cell is necessary for one-to-one fertilization (i.e., monospermy) of the central cell. In addition, using tetraspore mutants possessing multiple sperm cell pairs in one pollen, we demonstrated that normal double fertilization was observed even when excess sperm cells were released into the receptive region between the female gametes. In ovules accepting four sperm cells, the egg cell never fused with more than one sperm cell, whereas half of the central cells fused with more than one sperm cell (i.e., polyspermy) even 1 h later. Our results suggest that the central cell can block polyspermy during double fertilization, although the central cell is more permissive to polyspermy than the egg cell. The potential contribution of polyspermy block by the central cell is discussed in terms of how it is involved in the one-to-one distribution of the sperm cells to two distinct female gametes.

scholarly journals Relation of the male gametes with embryo sec cells. The hypothesis of double fertilization

2014 ◽  
Vol 50 (1-2) ◽  
pp. 173-175 ◽  
Author(s):  
N. S. Belayeva
Keyword(s):  
Membrane Damage ◽  
Sperm Nucleus ◽  
Central Nucleus ◽  
Egg Cell ◽  
Double Fertilization ◽  
Cell Membrane Damage ◽  
Male Gametes ◽  
Egg Membrane ◽  
A Cell ◽  
A Current

The sperms one after another get out of synergids. The front sperm gets the first into the egg cell attraction zone and then the sperm comes into contact with egg membrane. At this moment Attraction ceases and the second sperm is led by a current of cytoplasma to the central nucleus. In the egg cell the sperm nucleus is led to the nucleus by cytoplasmic current too. After fertilization the character of cytoplasmic motion changes, because of a cell membrane damage. The presence of the sperm in the female nuclei may also serve as a regulating factor.

Endosperm development in Zea mays; implication of gametic imprinting and paternal excess in regulation of transfer layer development

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3089-3097 ◽  
Author(s):  
W. L. Charlton ◽  
C. L. Keen ◽  
C. Merriman ◽  
P. Lynch ◽  
A. J. Greenland ◽  
...  
Keyword(s):  
Zea Mays ◽  
Sperm Nucleus ◽  
Endosperm Development ◽  
Central Cell ◽  
Egg Cell ◽  
Cell Nuclei ◽  
Transfer Layer ◽  
Sperm Nuclei ◽  
Gametic Imprinting ◽  
Layer Development

Fertilisation in maize (Zea mays), in common with most angiosperms, involves two fusion events: one of the two sperm nuclei unites with the egg cell nucleus, while the other sperm nucleus fuses with the two central cell nuclei giving rise to the triploid endosperm. Since deviation from this nuclear ratio (2:1 maternal/paternal) in the endosperm can result in abortion, it has been suggested that the genomes of the sperm and/or central cell are differentially imprinted during sexual development. By crossing a normal diploid maize line as female with its autotetraploid counterpart, an unbalanced genomic ratio (2:2 maternal/paternal) is created in the endosperm which often results in the eventual abortion of the tissue. Detailed structural comparison of these aberrant endosperms with normal endosperms reveals that the formation of the transfer cell layer, a tissue formed some 8 days after pollination and responsible for the transport of nutrients into the endosperm, is almost completely suppressed under conditions of paternal genomic excess. The first structural analysis of the development of this tissue in normal and aberrant endosperms is reported, and the implications of regulating the formation of such a tissue by gametically imprinted genes are discussed in the light of current theories on the consequences of genomic imbalance on early embryonic development.

scholarly journals Transcriptional repression specifies the central cell for double fertilization

2020 ◽  
Vol 117 (11) ◽  
pp. 6231-6236 ◽  
Author(s):  
Meng-Xia Zhang ◽  
Shan-Shan Zhu ◽  
Yong-Chao Xu ◽  
Ya-Long Guo ◽  
Wei-Cai Yang ◽  
...  
Keyword(s):  
Cell Fate ◽  
Transcriptional Repression ◽  
Female Gametophyte ◽  
Embryo Sac ◽  
Central Cell ◽  
Egg Cell ◽  
Accessory Cell ◽  
Double Fertilization ◽  
Genetic Rescue ◽  
Key Innovation

Double fertilization is a key innovation for the evolutionary success of angiosperms by which the two fertilized female gametes, the egg cell and central cell, generate the embryo and endosperm, respectively. The female gametophyte (embryo sac) enclosed in the sporophyte is derived from a one-celled haploid cell lineage. It undergoes successive events of mitotic divisions, cellularization, and cell specification to give rise to the mature embryo sac, which contains the two female gametes accompanied by two types of accessory cells, namely synergids and antipodals. How the cell fate of the central cell is specified has long been equivocal and is further complicated by the structural diversity of female gametophyte across plant taxa. Here, MADS-box protein AGL80 was verified as a transcriptional repressor that directly suppresses the expression of accessory cell-specific genes to specify the central cell. Further genetic rescue and phylogenetic assay of the AGL80 orthologs revealed a possible conserved mechanism in the Brassicaceae family. Results from this study provide insight into the molecular determination of the second female gamete cell in Brassicaceae.

scholarly journals Overcoming Pre-Fertilization Barriers in Intertribal Crosses between Anemone coronaria L. and Ranunculus asiaticus L.

Horticulturae ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 529
Author(s):  
Emmy Dhooghe ◽  
Dirk Reheul ◽  
Marie-Christine Van Labeke
Keyword(s):  
Pollen Tube ◽  
Seed Set ◽  
Sperm Nucleus ◽  
Tube Length ◽  
Egg Cell ◽  
Dichlorophenoxyacetic Acid ◽  
Style Length ◽  
Ranunculus Asiaticus ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Pollen Tube Length

Hybridization in flowering plants depends, in the first place, on the delivery of pollen to a receptive stigma and the subsequent growth of pollen tubes through the style to the ovary, where the sperm nucleus of the pollen grain can ultimately fertilize the egg cell. However, reproductive failure is often observed in distant crosses and is caused by pre- and/or post-zygotic barriers. In this study, the reproductive pre-fertilization barriers of intertribal crosses between Anemone coronaria L. and Ranunculus asiaticus L., both belonging to the Ranunculaceae, were investigated. Despite the incongruity of intertribal crosses between A. coronaria and R. asiaticus having been of low intensity at the stigmatic level, interstylar obstructions of the pollen tube growth occurred, which confirmed the presence of pre-fertilization barriers. We show that these barriers could be partially bypassed by combining pollination with a stigma treatment. More specifically, a significantly higher ratio of the pollen tube length to the total style length and a better seed set were observed when the stigma was treated with the auxin 2,4-dichlorophenoxyacetic acid (2,4-D, 1 mg.mL−1) together with the cytokinin kinetin (KIN, 0.5 mg.mL−1) 24 h after pollination, irrespective of the cross direction. More specifically, the stigma treatments with any form of auxin (combined or not combined with cytokinin) resulted in a full seed set, assuming an apomictic fruit set, because no pollination was needed to obtain these seeds.

scholarly journals Installasi Base Transceiver Station (BTS) untuk Jaringan Node B pada Operator Hutchison 3 Indonesia (H3I)

2015 ◽  
Vol 11 (1) ◽  
pp. 78
Author(s):  
Uzma Septima ◽  
Lince Markis
Keyword(s):  
Receive Signal ◽  
Network Operator ◽  
Long Distance ◽  
New Process ◽  
Station Base ◽  
Communication Links ◽  
Distance Communication ◽  
Base Transceiver Station ◽  
In Transit ◽  
Made In

Base Transceiver Station is a device used to connect mobile-phone or smartphone in order to make long-distance communication, although in doing the movement or in transit from one place to another. Installation Base Transceiver Station for Network Node B At the operator Hutchison 3 Indonesia is done to make the operator Hutchison 3 Indonesia signal received by the phone for the better and not dashed when the user performs long-distance communication links with conditions in performing the movement or in the course of one place to another. Methods beginning the process of physical installation of Base Transceiver Station for Node B network in the operator Hutchison 3 Indonesia and order all the Base Transceiver Station can live well after the battery is connected to a rectifier and the required accuracy when performing the installation Base Transceiver Station. Furthermore, the integration process or Commissioning of the Base Transceiver Station for Node B network operator Hutchison 3 Indonesia on this in order to actively and After Commissioning obtained Receive Signal Level sectoral antennas of -59 dBm which can emit a signal as far as 7 km to 8 km , after the new process or Pointing connection between this new Base Transceiver Station Base Transceiver Station with preexisting and Pointing between Siak new Base Transceiver Station Base Transceiver Station Perawang with Perawang Students who have a distance of 5 km Receive Signal level of -32.4 dBm made in accordance with a budget link provided operator Hutchison 3 Indonesia is -30 dBm to -40 dBm.

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