2,4-D Butoxyethyl Ester Kinetics in Embryos of Xenopus laevis: The Role of the Embryonic Jelly Coat in Reducing Chemical Absorption

2006 ◽  
Vol 52 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Andrea N. Edginton ◽  
Claude Rouleau ◽  
Gerald R. Stephenson ◽  
Herman J. Boermans
Keyword(s):  
Xenopus Laevis ◽  
Chemical Absorption ◽  
Jelly Coat

scholarly journals Imaging patterns of calcium transients during neural induction in Xenopus laevis embryos

2000 ◽  
Vol 113 (19) ◽  
pp. 3519-3529 ◽  
Author(s):  
C. Leclerc ◽  
S.E. Webb ◽  
C. Daguzan ◽  
M. Moreau ◽  
A.L. Miller
Keyword(s):  
Xenopus Laevis ◽  
Calcium Signalling ◽  
Neural Induction ◽  
Calcium Transients ◽  
Free Calcium ◽  
Treated Animal ◽  
Cell Stage ◽  
Subsequent Formation ◽  
Xenopus Laevis Embryos

Through the injection of f-aequorin (a calcium-sensitive bioluminescent reporter) into the dorsal micromeres of 8-cell stage Xenopus laevis embryos, and the use of a Photon Imaging Microscope, distinct patterns of calcium signalling were visualised during the gastrulation period. We present results to show that localised domains of elevated calcium were observed exclusively in the anterior dorsal part of the ectoderm, and that these transients increased in number and amplitude between stages 9 to 11, just prior to the onset of neural induction. During this time, however, no increase in cytosolic free calcium was observed in the ventral ectoderm, mesoderm or endoderm. The origin and role of these dorsal calcium-signalling patterns were also investigated. Calcium transients require the presence of functional L-type voltage-sensitive calcium channels. Inhibition of channel activation from stages 8 to 14 with the specific antagonist R(+)BayK 8644 led to a complete inhibition of the calcium transients during gastrulation and resulted in severe defects in the subsequent formation of the anterior nervous system. BayK treatment also led to a reduction in the expression of Zic3 and geminin in whole embryos, and of NCAM in noggin-treated animal caps. The possible role of calcium transients in regulating developmental gene expression is discussed.

scholarly journals Role of zinc in the control of oocyte maturation in Xenopus laevis

2000 ◽  
Vol 21 (3) ◽  
pp. 165-168 ◽  
Author(s):  
KEN-ICHI WATANABE ◽  
TOSHINOBU TOKUMOTO ◽  
KATSUTOSHI ISHIKAWA
Keyword(s):  
Xenopus Laevis ◽  
Oocyte Maturation

The role of water-regulating mechanisms in the development of the haploid syndrome in Xenopus laevis

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 449-462
Author(s):  
Louie Hamilton ◽  
P. H. Tuft
Keyword(s):  
Xenopus Laevis ◽  
Cell Number ◽  
Gastrula Stage ◽  
Tail Bud ◽  
Volume Changes ◽  
Membrane Area ◽  
Flow Through ◽  
The Difference ◽  
Haploid Embryos

The uptake of water by haploid and diploid sibling embryos of Xenopus laevis has been investigated by measuring the density changes which occur during the development of intact embryos from the blastula to the late tail-bud stage, and of explants from which most of the presumptive endoderm has been removed. The results show that up to the mid-gastrula stage there is no difference between the haploid and diploid embryos; but from then on, whereas the diploid volume increases steadily, the haploid gastrulae undergo a series of cyclical volume changes due to loss of fluid through the blastopore. It is concluded that this is the result of an excessive inflow of water through the haploid ectoderm, because it was found that the volume of haploid ectodermal explants increased much more rapidly than the volume of similar diploid explants. Excess flow through the haploid ectoderm also accounts for other characteristics of the haploid syndrome – microcephaly and lordosis. It is suggested that it is the doubling of the cell number in haploid embryos with the consequent 25% increase in aggregate cell membrane area which accounts for the difference between the uptake of water by the two types of embryos. It is also suggested that changes in the rate of water flow through the ectoderm and endoderm which are thought to account for the accumulation of water in the blastocoel and archenteron in the normal diploid embryo arise in a similar way.

The Effect of Chloroacetophenone on Chick Embryos Cultured in vitro

Development ◽  
1962 ◽  
Vol 10 (3) ◽  
pp. 373-382
Author(s):  
M. S. Lakshmi
Keyword(s):  
Xenopus Laevis ◽  
Average Length ◽  
Primitive Streak ◽  
Poultry Farm ◽  
Chick Embryos ◽  
Normal Process ◽  
Strong Emphasis ◽  
The Brain

Brachet's (1950) strong emphasis on the role of —SH-containing proteins in the process of induction has stimulated a study of the interference in the normal process of morphogenesis of chick embryos by chloroacetophenone, which has been described by Beatty (1951) as a specific and irreversible —SH inhibitor. He studied the effect of chloroacetophenone on the development of embryos of Rana and Triturus employing different concentrations. Deuchar (1957) also studied the action of the same chemical on the embryos of Xenopus laevis and has recorded abnormalities mainly in the brain and the eye. In the present work ω-chloroacetophenone (CAP) commercially known as phenacyl chloride (ω—C6H5.CO.CH2Cl) was employed. The sample used was a B.D.H. product. Fresh fertilized hens' eggs brought from a local poultry farm were incubated at 37·5° C. for 16 to 18 hours to obtain definitive primitive-streak stages (range of length from 1·75 mm. to 2 mm.) or for about 22 hours to obtain head-process stages (average length of the head process alone 0·56 mm.).

Structure of Four Acidic Oligosaccharides from the Jelly Coat Surrounding the Eggs of Xenopus Laevis

2008 ◽  
Vol 231 (2) ◽  
pp. 434-439
Author(s):  
Yves Plancke ◽  
Jean-Michel Wieruszeski ◽  
Catherine Alonso ◽  
Benoni Boilly ◽  
Gérard Strecker
Keyword(s):  
Xenopus Laevis ◽  
Jelly Coat

scholarly journals Embryonic Poly(A)-Binding Protein Stimulates Translation in Germ Cells

2005 ◽  
Vol 25 (5) ◽  
pp. 2060-2071 ◽  
Author(s):  
Gavin S. Wilkie ◽  
Philippe Gautier ◽  
Diane Lawson ◽  
Nicola K. Gray
Keyword(s):  
Xenopus Laevis ◽  
Oocyte Maturation ◽  
Germ Cells ◽  
Binding Protein ◽  
Expression Patterns ◽  
General Role ◽  
Early Embryos ◽  
Relative Divergence

ABSTRACT The function of poly(A)-binding protein 1 (PABP1) in poly(A)-mediated translation has been extensively characterized. Recently, Xenopus laevis oocytes and early embryos were shown to contain a novel poly(A)-binding protein, ePABP, which has not been described in other organisms. ePABP was identified as a protein that binds AU-rich sequences and prevents shortening of poly(A) tails. Here, we show that ePABP is also expressed in X. laevis testis, suggesting a more general role for ePABP in gametogenesis. We find that ePABP is conserved throughout vertebrates and that mouse and X. laevis cells have similar tissue-specific ePABP expression patterns. Furthermore, we directly assess the role of ePABP in translation. We show that ePABP is associated with polysomes and can activate the translation of reporter mRNAs in vivo. Despite its relative divergence from PABP1, we find that ePABP has similar functional domains and can bind to several PABP1 partners, suggesting that they may use similar mechanisms to activate translation. In addition, we find that PABP1 and ePABP can interact, suggesting that these proteins may be bound simultaneously to the same mRNA. Finally, we show that the activity of both PABP1 and ePABP increases during oocyte maturation, when many mRNAs undergo polyadenylation.

scholarly journals Role of the thrombopoietin (TPO)/Mpl system: c-Mpl-like molecule/TPO signaling enhances early hematopoiesis in Xenopus laevis

2002 ◽  
Vol 44 (1) ◽  
pp. 63-75 ◽  
Author(s):  
Minoru Kakeda ◽  
Jun-ichi Kyuno ◽  
Takashi Kato ◽  
Mitsuo Nishikawa ◽  
Makoto Asashima
Keyword(s):  
Xenopus Laevis

Cytochalasin B does not block sperm penetration into denuded starfish oocytes

Zygote ◽  
1994 ◽  
Vol 2 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Keiichiro Kyozuka ◽  
Kenzi Osanai
Keyword(s):  
Plasma Membrane ◽  
Actin Filament ◽  
Cytochalasin B ◽  
Sperm Head ◽  
Asterias Amurensis ◽  
Jelly Coat ◽  
Dense Cytoplasm ◽  
Sperm Penetration ◽  
Vitelline Coat

SummaryDuring fertilisation in starfish oocytes, the fertilisation cone develops temporarily beneath the penetrating sperm. The role of the fertilisation cone in sperm incorporation in the starfish Asterias amurensis was examined using cytochalasin B (CB). CB (2 μM) allowed sperm acrosomal process–egg plasma membrane fusion and egg activation, but inhibited the development of the fertilisation cone containing actin microfilaments. When sperm were added to intact oocytes (with the jelly coat and vitelline coat) in seawater containing CB, the sperm head did not penetrate the fertilisation membrane. Although the acrosomal process fused with egg plasma membrane, the sperm head remained outside the fertilisation membrane. On the other hand, denuded oocytes without the jelly coat and vitelline coat allowed sperm penetration even in the presence of 2 μM CB. Electron microscopy revealed that sperm organelles, including the acrosomal process, nucleus, mitochondrion and tail, were incorporated into the slightly electron-dense cytoplasm, which was similar to the cytoplasm of the fertilisation cone. These results show that the development of the fertilisation cone/actin filament complex is not essential for incorporation of the sperm, since incorporation can occur in denuded oocytes. However, the cone is required for fertilisation of intact oocytes, suggesting that this actin-filament-containing structure is necessary for getting the sperm through the outer egg coats.

scholarly journals Histone H1 is essential for mitotic chromosome architecture and segregation in Xenopus laevis egg extracts

2005 ◽  
Vol 169 (6) ◽  
pp. 859-869 ◽  
Author(s):  
Thomas J. Maresca ◽  
Benjamin S. Freedman ◽  
Rebecca Heald
Keyword(s):  
Xenopus Laevis ◽  
Metaphase Plate ◽  
Histone H1 ◽  
Linker Histone ◽  
Chromosome Architecture ◽  
Linker Histone H1 ◽  
Egg Extracts ◽  
Chromatin Proteins ◽  
And Function

During cell division, condensation and resolution of chromosome arms and the assembly of a functional kinetochore at the centromere of each sister chromatid are essential steps for accurate segregation of the genome by the mitotic spindle, yet the contribution of individual chromatin proteins to these processes is poorly understood. We have investigated the role of embryonic linker histone H1 during mitosis in Xenopus laevis egg extracts. Immunodepletion of histone H1 caused the assembly of aberrant elongated chromosomes that extended off the metaphase plate and outside the perimeter of the spindle. Although functional kinetochores assembled, aligned, and exhibited poleward movement, long and tangled chromosome arms could not be segregated in anaphase. Histone H1 depletion did not significantly affect the recruitment of known structural or functional chromosomal components such as condensins or chromokinesins, suggesting that the loss of H1 affects chromosome architecture directly. Thus, our results indicate that linker histone H1 plays an important role in the structure and function of vertebrate chromosomes in mitosis.

Sign in / Sign up

Export Citation Format

Share Document