The degree of determination of the early embryo of Schistocerca gregaria (Forskål) (Orthoptera: Acrididae)

Development ◽  
1971 ◽  
Vol 25 (3) ◽  
pp. 277-299
Author(s):  
S. K. Moloo
Keyword(s):  
Early Development ◽  
Schistocerca Gregaria ◽  
Early Embryo ◽  
Germ Band ◽  
Early Cleavage ◽  
Band Formation ◽  
Zygote Nucleus ◽  
Young Embryo ◽  
Blastoderm Stage

The degree of determination of the young embryo of S. gregaria has been investigated using ligation, thermocautery and centrifugation techniques. From the overall results, it is suggested that the early development of the embryo is mediated by two physiological centres. The formation of the germ rudiment is controlled by an activation centre located in the periplasm round the posterior end of the egg. This centre is already present at the zygote nucleus stage and is essential during the very early cleavage period. The differentiation of the germ band is induced by the activity of a second centre, the differentiation centre, located in the presumptive thorax. It apparently becomes established at least by the late blastoderm stage and its activity continues during the period of germ-band formation. During the late cleavage and early blastoderm stages, the egg is labile and the embryo is therefore able to normalize its development after part or parts of the germinal Anlage have been cauterized, removed or displaced. The differentiation centre completes its functions by the beginning of gastrulation. Thereafter, the embryo is determined. The embryo can regulate its size at least up to the gastrulation stage provided that a certain minimum amount of usable yolk is available. The development of the serosa is not under the control of either centre. This structure seems to be capable of regeneration providing that a part of the extra-embryonic blastoderm remains intact.

Dax, a locust Hox gene related to fushi-tarazu but showing no pair-rule expression

Development ◽  
1994 ◽  
Vol 120 (6) ◽  
pp. 1561-1572 ◽  
Author(s):  
R. Dawes ◽  
I. Dawson ◽  
F. Falciani ◽  
G. Tear ◽  
M. Akam
Keyword(s):  
Schistocerca Gregaria ◽  
Posterior Part ◽  
Homeobox Gene ◽  
Early Embryo ◽  
Neural Precursor Cells ◽  
Germ Band ◽  
Fushi Tarazu ◽  
Hox Gene ◽  
Two Phases ◽  
Pair Rule

We describe an unusual Antennapedia class homeobox gene from the grasshopper Schistocerca gregaria (Orthoptera, African Plague Locust). Its sequence is not sufficiently similar to that of any other insect Hom-Hox gene to identify it unambiguously, but short conserved elements suggest a relationship to the segmentation gene fushi-tarazu, (ftz). We term it Sg Dax (divergent Antennapedia class homeobox gene). Antibodies raised against the protein encoded by this gene reveal two phases of expression during embryogenesis. In the early embryo, it is a marker for the posterior part of the forming embryonic primordium, and subsequently for the posterior part of the growing germ band. In older embryos, it labels a subset of neural precursor cells in each trunk segment, very similar to that defined by the expression of fushi tarazu (ftz) in Drosophila. We suggest that Schistocerca Dax and Drosophila ftz are homologous members of a gene family whose members are diverging relatively rapidly, both in terms of sequence and role in early development.

X-ray Inactivation of Nuclei as a Method for Studying their Function in the Early Development of Fishes

Development ◽  
1959 ◽  
Vol 7 (2) ◽  
pp. 173-192
Author(s):  
A. A. Neyfakh
Keyword(s):  
Ionizing Radiation ◽  
Early Development ◽  
Nuclear Region ◽  
Blastula Stage ◽  
Early Cleavage ◽  
X Ray ◽  
Male Nucleus ◽  
Cleavage Stages ◽  
Heavy Dose

It is generally accepted at present that during cleavage in echinoderms, amphibians, and fishes, the nuclei do not have specific functions in regulating development, their role being at this time restricted to participation in the processes of cleavage (Schechtman & Nishihara, 1955). Eggs devoid of nuclei sometimes begin cleavage which may proceed up to the stage of the late blastula. Extirpation or inactivation of nuclei may be achieved through the separation of the nuclear region of the egg by means of centrifugation (Harvey, 1940); through extirpation of the female nucleus followed by fertilization with sperm inactivated by a heavy dose of radiation (Briggs, Green, & King, 1951); through spontaneous degeneration of the male nucleus during artificial androgenesis (Stauffer, 1945); and by means of other techniques. Exposure of early cleavage stages in amphibians (Mangold & Peters, 1956; Sanides, 1956) and fishes (Neyfakh, 1956a) to heavy doses of ionizing radiation also leads to arrest of development at the late blastula stage.

Interactions between the pair-rule genes runt, hairy, even-skipped and fushi tarazu and the establishment of periodic pattern in the Drosophila embryo

Development ◽  
1988 ◽  
Vol 104 (Supplement) ◽  
pp. 51-60 ◽  
Author(s):  
Philip Ingham ◽  
Peter Gergen
Keyword(s):  
Double Mutant ◽  
Early Embryo ◽  
Drosophila Embryo ◽  
Periodic Pattern ◽  
Fushi Tarazu ◽  
Blastoderm Stage ◽  
Pair Rule

The pair-rule genes of Drosophila play a fundamental role in the generation of periodicity in the early embryo. We have analysed the transcript distributions of runt, hairy, even-skipped and fushi tarazu in single and double mutant ernbryos. The results indicate a complex set of interactions between the genes during the blastoderm stage of embryogenesis.

Biphasic activation of the BMP pathway patterns the Drosophila embryonic dorsal region

Development ◽  
2001 ◽  
Vol 128 (6) ◽  
pp. 965-972 ◽  
Author(s):  
R. Dorfman ◽  
B.Z. Shilo
Keyword(s):  
Inhibitory Activity ◽  
Early Phase ◽  
Drosophila Embryo ◽  
Activation Pattern ◽  
Wild Type ◽  
Germ Band ◽  
Dorsal Region ◽  
Bmp Pathway ◽  
Simultaneous Activation ◽  
Blastoderm Stage

The BMP pathway patterns the dorsal region of the Drosophila embryo. Using an antibody recognizing phosphorylated Mad (pMad), we followed signaling directly. In wild-type embryos, a biphasic activation pattern is observed. At the cellular blastoderm stage high pMad levels are detected only in the dorsal-most cell rows that give rise to amnioserosa. This accumulation of pMad requires the ligand Screw (Scw), the Short gastrulation (Sog) protein, and cleavage of their complex by Tolloid (Tld). When the inhibitory activity of Sog is removed, Mad phosphorylation is expanded. In spite of the uniform expression of Scw, pMad expansion is restricted to the dorsal domain of the embryo where Dpp is expressed. This demonstrates that Mad phosphorylation requires simultaneous activation by Scw and Dpp. Indeed, the early pMad pattern is abolished when either the Scw receptor Saxophone (Sax), the Dpp receptor Thickveins (Tkv), or Dpp are removed. After germ band extension, a uniform accumulation of pMad is observed in the entire dorsal domain of the embryo, with a sharp border at the junction with the neuroectoderm. From this stage onward, activation by Scw is no longer required, and Dpp suffices to induce high levels of pMad. In these subsequent phases pMad accumulates normally in the presence of ectopic Sog, in contrast to the early phase, indicating that Sog is only capable of blocking activation by Scw and not by Dpp.

scholarly journals Genome-wide measurement of spatial expression in patterning mutants of Drosophila melanogaster

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 41 ◽  
Author(s):  
Peter A. Combs ◽  
Michael B. Eisen
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Early Embryo ◽  
Integrated Analysis ◽  
Spatial Patterning ◽  
Maternal Factors ◽  
Genome Wide ◽  
Binding Data ◽  
Complex Dependence ◽  
Blastoderm Stage

Patterning in the Drosophila melanogaster embryo is affected by multiple maternal factors, but the effect of these factors on spatial gene expression has not been systematically analyzed. Here we characterize the effect of the maternal factors Zelda, Hunchback and Bicoid by cryosectioning wildtype and mutant blastoderm stage embryos and sequencing mRNA from each slice. The resulting atlas of spatial gene expression highlights the intersecting roles of these factors in regulating spatial patterns, and serves as a resource for researchers studying spatial patterning in the early embryo. We identify a large number of genes with both expected and unexpected patterning changes, and through integrated analysis of transcription factor binding data identify common themes in genes with complex dependence on these transcription factors.

scholarly journals mRNA Expression and Role of PPARγ and PPARδ in Bovine Preimplantation Embryos Depending on the Quality and Developmental Stage

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2358
Author(s):  
Katarzyna Suwik ◽  
Emilia Sinderewicz ◽  
Dorota Boruszewska ◽  
Ilona Kowalczyk-Zięba ◽  
Joanna Staszkiewicz-Chodor ◽  
...  
Keyword(s):  
Early Development ◽  
Embryo Development ◽  
Embryo Quality ◽  
Early Embryo ◽  
Developmental Competence ◽  
Preimplantation Embryos ◽  
Peroxisome Proliferator ◽  
Early Embryo Development ◽  
Quality Markers

Peroxisome proliferator-activated receptors (PPARs), a nuclear receptors for prostacyclin (PGI2) have been recognized as being essential for early embryo development. The objectives of the present study were to determine if the bovine early- and late-cleaved embryos in different stages of early development express PPARγ and PPARδ. Since embryo developmental competence depends on numerous biological factors, we evaluated if the expression of PPARγ and PPARδ correlate with selected embryo quality markers (SOX2, OCT4, PLAC8, IGF1R) in the in vitro produced embryos at different stages of their development. Developmental rates and embryo quality for early- and late-cleaved embryos were provided according to International Embryo Transfer Society (IETS; developmental stages: 2-, 4-, 16-cell embryo, morula, blastocyst (1—early, 2—developing, 3—expanded, 4—hatched); quality stages: A—high quality, B—moderate quality, C—low quality). We found that bovine embryos expressed mRNA of PPARδ and PPARγ at all stages of early development, independently of their quality. In addition, the expression of PPARδ and PPARγ correlated with the expression of quality markers in bovine blastocysts. Positive correlations were stronger and more frequent in the group of early-cleaved embryos, whereas the negative correlations were typical for the group of late-cleaved embryos. Obtained results and available literature reports may indicate the participation of PGI2, via PPARδ and PPARγ, in the processes related to the early embryo development, through the participation of this factor in the modulation of blastocyst hatching, implantation, and post-implantation development.

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