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 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 Early events during embryogenesis in Zea mays L.

2014 ◽  
Vol 50 (1-2) ◽  
pp. 289-290 ◽  
Author(s):  
A. A. Van Lammeren
Keyword(s):  
Zea Mays ◽  
Structural Changes ◽  
Zea Mays L ◽  
Mature Embryo ◽  
Early Embryogenesis ◽  
Central Cell ◽  
Egg Cell ◽  
Cellular Endosperm ◽  
Well Differentiated

The megagametophyte of <em>Zea mays</em> L. undergoes a series of structural changes after fertilization resulting in a well differentiated mature embryo and cellular endosperm at 480 hours after pollination in greenhouse conditions. In the present work emphasis was laid on the localization of the cytoplasm in the synergids, central cell-endosperm and egg cell-zygote prior to and after fertilization. The observations are discussed in relation to the process of early embryogenesis.

Isolation and microinjection of active sperm nuclei into egg cells and central cells of isolated maize embryo sacs

Zygote ◽  
1994 ◽  
Vol 2 (1) ◽  
pp. 29-35 ◽  
Author(s):  
E. Matthys-Rochon ◽  
R. Mòl ◽  
P. Heizmann ◽  
C. Dumas
Keyword(s):  
Transcriptional Activity ◽  
Pollen Grains ◽  
Central Cell ◽  
Egg Cell ◽  
Percoll Gradient ◽  
Single Male ◽  
Nucleotide Incorporation ◽  
Maize Embryo ◽  
Sperm Nuclei

SummaryArtificial fertilisation was attempted in maize by microinjecting sperm nuclei into the egg cell or central cell of isolated embryo sacs. A protocol for isolation of nuclei from pollen grains was developed and a pure fraction of sperm nuclei was obtained after centrifugation on a Percoll gradient. The in vitro transcriptional activity of the nuclei was tested by incorporation of radioactive UTP into RNA. The level of labelled nucleotide incorporation increased and reached a maximum after between 30 and 40 min in the incubation medium. The embryo sacs were enzymatically isolated and their viability determined by observation of cytoplasmic streaming in the female cells. The embryo sacs were immobilised by embedding in low-melting-point agarose and a single male nucleus was injected with a bevelled microcapillary. The presence of the injected nucleus in the egg or central cell was demonstrated using a cytological approach. This paper presents an alternative method for studying the intimate processes of fertilisation in plants.

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 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.

A High Resolution Cytochemical Study of Nuclear ATPase in Human Spermatozoa

1975 ◽  
Vol 33 ◽  
pp. 594-595
Author(s):  
A. Sosa ◽  
L. Calzada
Keyword(s):  
High Resolution ◽  
Atpase Activity ◽  
Nuclear Membrane ◽  
Human Sperm ◽  
Sperm Nucleus ◽  
Human Spermatozoa ◽  
Cytochemical Study ◽  
Membrane Bound ◽  
Sperm Nuclei ◽  
Interchromatin Space

The dependence of nuclear metabolism on the function of the nuclear membrane is not well understood. Whether or not the function of the nuclear membrane is partial or totally responsible of the repressed template activity of human sperm nucleus has not at present been elucidated. One of the membrane-bound enzymatic activities which is concerned with the mechanisms whereby substances are thought to cross cell membranes is adenosintriphosphatase (ATPase). This prompted its characterization and distribution by high resolution photogrammetry on isolated human sperm nuclei. Isolated human spermatozoa nuclei were obtained as previously described. ATPase activity was demonstrated by the method of Wachstein and Meisel modified by Marchesi and Palade. ATPase activity was identified as dense and irregularly distributed granules confined to the internal leaflet of the nuclear membrane. Within the nucleus the appearance of the reaction product occurs as homogenous and dense precipitates in the interchromatin space.

Role of karyoplasm in the emergence of capacity of egg cytoplasm to induce DNA synthesis in transplanted sperm nuclei

Development ◽  
1976 ◽  
Vol 36 (1) ◽  
pp. 67-72
Author(s):  
M. N. Skoblina
Keyword(s):  
Dna Synthesis ◽  
Sperm Nucleus ◽  
Germinal Vesicles ◽  
Sperm Nuclei

The behaviour of sperm nuclei was studied both in the cytoplasm of intact toad oocytes undergoing maturation and the cytoplasm of oocytes matured without germinal vesicles. The behaviour of the nuclei of pronase-treated sperm injected in the mature egg cytoplasm was shown to be exactly similar to that of the sperm nucleus after fertilization, i.e. they swelled, synthesized DNA, and divided. No changes in such sperm nuclei could be detected in the cytoplasm of the oocytes matured without germinal vesicles.

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.

Mechanisms of displacement of sperm basic nuclear proteins in mammals. An in vitro simulation of post-fertilization results

1982 ◽  
Vol 53 (1) ◽  
pp. 227-244
Author(s):  
T.C. Rodman ◽  
F.H. Pruslin ◽  
V.G. Allfrey
Keyword(s):  
Sperm Nucleus ◽  
Nuclear Proteins ◽  
Mouse Sperm ◽  
Basic Proteins ◽  
Molecular Events ◽  
In Vitro Simulation ◽  
Sperm Nuclei ◽  
Two Parameters

A standardized cytological preparation of mature mouse sperm has been devised to serve as an in vitro system for probing the intra-ooplasmic molecular events of transformation of the fertilizing sperm. Two parameters of the early phase of transformation in vivo are defined at the resolution of the light microscope: deletion of sperm-unique nuclear proteins, detectable by immunofluorescence, and retention of homogeneity of the residual DNA complex, with intact chromatin boundaries detectable by ethidium bromide staining. These studies show that both parameters are conserved when in vitro sperm preparations are treated with NaCl under reducing conditions. The deletion of 2 different classes of the unique basic proteins of mouse sperm nuclei is specified by the NaCl concentration: 0.7 M-NaCl displaces the non-protamine class but not the protamines, while 1 M-NaCl displaces both. On the other hand the effects of treatment with trypsin at various concentrations and intervals are less consistent with the in vivo parameters, indicating fragmentation and displacement, not only of the sperm-unique basic proteins, but also of structural proteins believed to maintain the fundamental cohesive organization of the DNA matrix. These observations suggest that mechanisms other than proteolysis, e.g. localized changes in ionic concentrations, may participate in the post-fertilization displacement of the sperm-unique nuclear proteins in vivo. This study also supports the validity of the in vitro simulation as a model with which to probe the progression of transformation of the sperm nucleus to the zygote pronucleus.

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