Fine Structure of Four-Nucleate Stages and the Central Cell of Lilium Regale Embryo Sac

1967 ◽  
Vol 157 (5) ◽  
pp. 365-371
Author(s):  
E. Mikulska ◽  
B. Rodkiewicz
Keyword(s):  
Fine Structure ◽  
Embryo Sac ◽  
Central Cell ◽  
Lilium Regale

Development of a Heat-Inducible Gene Expression System Using Female Gametophytes of Arabidopsis thaliana

2019 ◽  
Vol 60 (11) ◽  
pp. 2564-2572 ◽  
Author(s):  
Dukhyun Hwang ◽  
Satomi Wada ◽  
Azusa Takahashi ◽  
Hiroko Urawa ◽  
Yasuhiro Kamei ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Expression System ◽  
Embryo Sac ◽  
Gene Induction ◽  
Central Cell ◽  
Egg Cell ◽  
Dominant Negative Mutant ◽  
Nucleate Cell ◽  
Recombination System ◽  
Induction System

Abstract Female gametophyte (FG) is crucial for reproduction in flowering plants. Arabidopsis thaliana produces Polygonum-type FGs, which consist of an egg cell, two synergid cells, three antipodal cells and a central cell. Egg cell and central cell are the two female gametes that give rise to the embryo and surrounding endosperm, respectively, after fertilization. During the development of a FG, a single megaspore produced by meiosis undergoes three rounds of mitosis to produce an eight-nucleate cell. A seven-celled FG is formed after cellularization. The central cell initially contains two polar nuclei that fuse during female gametogenesis to form the secondary nucleus. In this study, we developed a gene induction system for analyzing the functions of various genes in developing Arabidopsis FGs. This system allows transgene expression in developing FGs using the heat-inducible Cre-loxP recombination system and FG-specific embryo sac 2 (ES2) promoter. Efficient gene induction was achieved in FGs by incubating flower buds and isolated pistils at 35�C for short periods of time (1–5 min). Gene induction was also induced in developing FGs by heat treatment of isolated ovules using the infrared laser-evoked gene operator (IR-LEGO) system. Expression of a dominant-negative mutant of Sad1/UNC84 (SUN) proteins in developing FGs using the gene induction system developed in this study caused defects in polar nuclear fusion, indicating the roles of SUN proteins in this process. This strategy represents a new tool for analyzing the functions of genes in FG development and FG functions.

Fine Structure of a Developing Embryo Sac of Lilium candidum

1965 ◽  
Vol 155 (4) ◽  
pp. 586-595
Author(s):  
E. Mikulska ◽  
B. Rodkiewicz
Keyword(s):  
Fine Structure ◽  
Embryo Sac

scholarly journals Embryo sac haustorium in Dryas octopetala L. (Rosaceae)

2014 ◽  
Vol 56 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Romana Czapik
Keyword(s):  
Embryo Sac ◽  
First Record ◽  
Central Cell ◽  
Characteristic Shape ◽  
Dense Cytoplasm ◽  
Dryas Octopetala ◽  
Tatra Mts

The embryo sac haustorium found in <em>Dryas octopetala</em> L. from the Tatra Mts is the first record of its occurrence in <em>Rosaceae</em>. At the eight-nucleate stage of the embryo sac, the antipodal end of the central cell began to grow into a narrow caecum filled with dense cytoplasm and elongated in the chalazal direction leaving the three antipodals in situ. The haustorium enlarged and lost its characteristic shape after the period of fertilization. Finally, the embryo sac occupied almost the whole length of the ovule. Situated at its chalazal end there was either dense cytoplasm with a group of endosperm nuclei or dense, grainy cytoplasm only, if fertilization had not taken place.

Ultrastructure of the developing embryo sac of sunflower (Helianthus annuus) before and after fertilization

1991 ◽  
Vol 69 (1) ◽  
pp. 191-202 ◽  
Author(s):  
Hua Yan ◽  
Hong-Yuan Yang ◽  
William A. Jensen
Keyword(s):  
Plasma Membrane ◽  
Helianthus Annuus ◽  
Embryo Sac ◽  
Active Role ◽  
Central Cell ◽  
Wall Material ◽  
Young Embryo ◽  
Before And After ◽  
Membrane Contact ◽  
Female Germ Unit

The ultrastructure of the embryo sac of the sunflower (Helianthus annuus) was investigated before and after fertilization. In the young embryo sac, walls were observed that completely surrounded the egg, synergids, and the central cell. However, as maturation continued, the extent of the wall changed. By the time the embryo was mature, the chalazal portion of the walls of the egg and synergids had disappeared so these cells have a plasma membrane to plasma membrane contact. This is also true for the central cell, which has plasma membrane contact with the egg and synergids. However, the chalazal and lateral walls of the central cell become considerably thicker at this time. Before the entry of the pollen tube, the synergid that is located toward the placenta degenerates. After fertilization, a wall forms over the chalazal portion of the zygote and the persistent synergid. The endosperm appears to play an active role in this process, contributing substantial amounts of wall material. However, the wall covering the chalazal portion of the zygote is not complete by the time the zygote divides. In the proembryo, ribosome density increases and lipid bodies decrease in number. The suspensory cell has autophagic vacuoles that encircle some of the organelles. Our results support the concept that the egg, synergids, and central cell form a single functional unit, the female germ unit. Key words: sunflower, ultrastructure, embryo sac, female germ unit.

Cytoskeletal organisation and modification during pollen tube arrival, gamete delivery and fertilisation in Plumbago zeylanica

Zygote ◽  
1993 ◽  
Vol 1 (2) ◽  
pp. 143-154 ◽  
Author(s):  
Bing-Quan Huang ◽  
Elisabeth S. Pierson ◽  
Scott D. Russell ◽  
Antonio Tiezzi ◽  
Mauro Cresti
Keyword(s):  
Pollen Tube ◽  
Embryo Sac ◽  
Central Cell ◽  
Egg Cell ◽  
Target Cells ◽  
Sperm Cells ◽  
Plumbago Zeylanica ◽  
Rhodamine Phalloidin ◽  
Male Gametes ◽  
Pollen Tube Penetration

The cytoskeletal organisation of the isolated embryo sac and egg cells of Plumbago zeylanica was examined before, during and after pollen tube penetration into the embryo sac to determine the potential involvement of microtubules and actin filaments in fertilisation. Material was singly and triply stained using Hoechst 33258 to localise DNA, fluorescein isothiocyanate (FITC)-labelled anti- α-tubulin to detect microtubules and rhodamine-phalloidin to visualise F-actin. Microtubules in the unfertilised egg cell are longitudinally aligned in the micropylar and mid-lateral areas, aggregating into bundles near the filiform apparatus. In the perinuclear cytoplasm of the egg cell, microtubules become more or less randomly aligned. F-actin bundles form a longitudinally aligned mesh in the chalazal cytoplasm of the egg cell. In the central cell, microtubules and F-actin are distributed along transvacuolar strands and are also evident in the perinuclear region and at the periphery of the cell. During pollen tube penetration, sparse microtubule bundles near the pathway of the pollen tube may form an apparent microtubular ‘conduit’ surrounding the male gametes at the delivery site. Actin aggregates become organised near the pathway of the pollen tube and at the delivery site of the sperm cells. Subsequently, actin aggregates form a ‘corona’ structure in the intercellular region between the egg and central cell where gametic fusion occurs. The corona may have a role in maintaining the close proximity of the egg and central cell and helping the two sperm cells move and bind to their target cells. The cytoskeleton may also be involved in causing the two nuclei of the egg and central cell to approach one another at the site of gametic fusion and transporting the two sperm nuclei into alignment with their respective female nucleus. The cytoskeleton is reorganised during early embryogenesis.

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