The zygotic expression of zebrafish trebf during embryogenesis is restricted to the embryonic shield and its derivatives

2001 ◽  
Vol 211 (8-9) ◽  
pp. 445-448 ◽  
Author(s):  
Liyun Liang ◽  
Ming Li ◽  
Ying Wang ◽  
Chengtian Zhao ◽  
Zhixing Zhao ◽  
...  
Keyword(s):  
Embryonic Shield

Axis-inducing activities and cell fates of the zebrafish organizer

Development ◽  
2000 ◽  
Vol 127 (16) ◽  
pp. 3407-3417 ◽  
Author(s):  
L. Saude ◽  
K. Woolley ◽  
P. Martin ◽  
W. Driever ◽  
D.L. Stemple
Keyword(s):  
Organizer Region ◽  
Complete Removal ◽  
Floor Plate ◽  
Significant Loss ◽  
Cell Fates ◽  
Deep Tissue ◽  
Head Formation ◽  
Prechordal Plate ◽  
Embryonic Shield ◽  
Organizer Activity

We have investigated axis-inducing activities and cellular fates of the zebrafish organizer using a new method of transplantation that allows the transfer of both deep and superficial organizer tissues. Previous studies have demonstrated that the zebrafish embryonic shield possesses classically defined dorsal organizer activity. When we remove the morphologically defined embryonic shield, embryos recover and are completely normal by 24 hours post-fertilization. We find that removal of the morphological shield does not remove all goosecoid- and floating head-expressing cells, suggesting that the morphological shield does not comprise the entire organizer region. Complete removal of the embryonic shield and adjacent marginal tissue, however, leads to a loss of both prechordal plate and notochord. In addition, these embryos are cyclopean, show a significant loss of floor plate and primary motorneurons and display disrupted somite patterning. Motivated by apparent discrepancies in the literature we sought to test the axis-inducing activity of the embryonic shield. A previous study suggested that the shield is capable of only partial axis induction, specifically being unable to induce the most anterior neural tissues. Contrary to this study, we find shields can induce complete secondary axes when transplanted into host ventral germ-ring. In induced secondary axes donor tissue contributes to notochord, prechordal plate and floor plate. When explanted shields are divided into deep and superficial fragments and separately transplanted we find that deep tissue is able to induce the formation of ectopic axes with heads but lacking posterior tissues. We conclude that the deep tissue included in our transplants is important for proper head formation.

Anteroposterior patterning in the zebrafish, Danio rerio: an explant assay reveals inductive and suppressive cell interactions

Development ◽  
1996 ◽  
Vol 122 (6) ◽  
pp. 1873-1883 ◽  
Author(s):  
C.G. Sagerstrom ◽  
Y. Grinblat ◽  
H. Sive
Keyword(s):  
Danio Rerio ◽  
Neural Induction ◽  
Active Role ◽  
Cell Number ◽  
Type I ◽  
Animal Pole ◽  
Anteroposterior Patterning ◽  
Embryonic Shield ◽  
Low Levels ◽  
Neural Markers

We report the first extended culture system for analysing zebrafish (Danio rerio) embryogenesis with which we demonstrate neural induction and anteroposterior patterning. Explants from the animal pole region of blastula embryos ('animal caps') survived for at least two days and increased in cell number. Mesodermal and neural-specific genes were not expressed in cultured animal caps, although low levels of the dorsoanterior marker otx2 were seen. In contrast, we observed strong expression of gta3, a ventral marker and cyt1, a novel type I cytokeratin expressed in the outer enveloping layer. Isolated ‘embryonic shield’, that corresponds to the amphibian organizer and amniote node, went on to express the mesodermal genes gsc and ntl, otx2, the anterior neural marker pax6, and posterior neural markers eng3 and krx20. The expression of these genes defined a precise anteroposterior axis in shield explants. When conjugated to animal caps, the shield frequently induced expression of anterior neural markers. More posterior markers were rarely induced, suggesting that anterior and posterior neural induction are separable events. Mesodermal genes were also seldom activated in animal caps by the shield, demonstrating that neural induction did not require co-induction of mesoderm in the caps. Strikingly, ventral marginal zone explants suppressed the low levels of otx2 in animal caps, indicating that ventral tissues may play an active role in axial patterning. These data suggest that anteroposterior patterning in the zebrafish is a multi-step process.

Developmental rate and allocation of transgenic cells in rabbit chimeric embryos

Zygote ◽  
2008 ◽  
Vol 16 (1) ◽  
pp. 87-91 ◽  
Author(s):  
P. Chrenek ◽  
A.V. Makarevich ◽  
M. Bauer ◽  
R. Jurcik
Keyword(s):  
Developmental Rate ◽  
Blastocyst Stage ◽  
Egfp Expression ◽  
Control Group ◽  
Cell Stage ◽  
Embryonic Shield ◽  
Developmental Capacity ◽  
Transgenic Cells ◽  
Average Total Number ◽  
Rabbit Embryos

SummaryThe objective of this study was to compare developmental capacity of rabbit chimeric embryos and the allocation of the EGFP gene expression to the embryoblast (ICM) or embryonic shield. We produced chimeric embryos (TR<>N) by synchronous transfer of two or three blastomeres at the 16-cell stage from transgenic (TR) into normal host embryos (N) at the same stage. In the control group, two to three non-transgenic blastomeres were used to produce chimeric embryos. The TR embryos were produced by microinjection of EGFP into both pronuclei of fertilized rabbit eggs. The developmental rate and allocation of EGFP-positive cells of the reconstructed chimeric embryos was controlled at blastocyst (96 h PC) and embryonic shield (day 6) stage.All chimeric embryos (120/120, 100%) developed up to blastocyst stage. Using fluorescent microscope, we detected green signal (EGFP expression). In 90 chimeric (TR<>N) embryos (75%). Average total number of cells in chimeric embryos at blastocyst stage was 175 ± 13.10, of which 58 ± 2.76 cells were found in the ICM area. The number of EGFP-positive cells in the ICM area was 24 ± 5.02 (35%). After the transfer of 50 chimeric rabbit embryos at the 16-cell stage, 20 embryos (40%) were flushed from five recipients on day 6 of pregnancy, of which five embryos (25%) were EGFP positive at the embryonic shield stage.Our results demonstrate that transgenic blastomeres in synchronous chimeric embryos reconstructed from TR embryos have an ability to develop and colonize ICM and embryonic shield area.

scholarly journals Six3, a medaka homologue of the Drosophila homeobox gene sine oculis is expressed in the anterior embryonic shield and the developing eye

1998 ◽  
Vol 74 (1-2) ◽  
pp. 159-164 ◽  
Author(s):  
Felix Loosli ◽  
Reinhard W. Köster ◽  
Matthias Carl ◽  
Annette Krone ◽  
Joachim Wittbrodt
Keyword(s):  
Homeobox Gene ◽  
Sine Oculis ◽  
Embryonic Shield

scholarly journals Characterizing the zebrafish organizer: microsurgical analysis at the early-shield stage

Development ◽  
1996 ◽  
Vol 122 (4) ◽  
pp. 1313-1322 ◽  
Author(s):  
J. Shih ◽  
S.E. Fraser
Keyword(s):  
Neural Development ◽  
Neural Induction ◽  
Leading Edge ◽  
Axis Formation ◽  
Embryonic Patterning ◽  
Fish Embryo ◽  
Embryo Patterning ◽  
Embryonic Shield ◽  
Microsurgical Techniques ◽  
Notochord Cells

The appearance of the embryonic shield, a slight thickening at the leading edge of the blastoderm during the formation of the germ ring, is one of the first signs of dorsoventral polarity in the zebrafish embryo. It has been proposed that the shield plays a role in fish embryo patterning similar to that attributed to the amphibian dorsal lip. In a recent study, we fate mapped many of the cells in the region of the forming embryonic shield, and found that neural and mesodermal progenitors are intermingled (Shih, J. and Fraser, S.E. (1995) Development 121, 2755–2765), in contrast to the coherent region of mesodermal progenitors found at the amphibian dorsal lip. Here, we examine the fate and the inductive potential of the embryonic shield to determine if the intermingling reflects a different mode of embryonic patterning than that found in amphibians. Using the microsurgical techniques commonly used in amphibian and avian experimental embryology, we either grafted or deleted the region of the embryonic shield. Homotopic grafting experiments confirmed the fates of cells within the embryonic shield region, showing descendants in the hatching gland, head mesoderm, notochord, somitic mesoderm, endoderm and ventral aspect of the neuraxis. Heterotopic grafting experiments demonstrated that the embryonic shield can organize a second embryonic axis; however, contrary to our expectations based on amphibian research, the graft contributes extensively to the ectopic neuraxis. Microsurgical deletion of the embryonic shield region at the onset of germ ring formation has little effect on neural development: embryos with a well-formed and well-patterned neuraxis develop in the complete absence of notochord cells. While these results show that the embryonic shield is sufficient for ectopic axis formation, they also raise questions concerning the necessity of the shield region for neural induction and embryonic patterning after the formation of the germ ring.

Distribution of Glycogen in the Developing Salmon (Salmo Salar L.)

1947 ◽  
Vol 24 (1-2) ◽  
pp. 123-144
Author(s):  
R. J. DANIEL
Keyword(s):  
Muscle Tissue ◽  
Circulatory System ◽  
Liver Cells ◽  
Yolk Sac ◽  
General Distribution ◽  
Muscle Fibres ◽  
Staining Reaction ◽  
Embryonic Shield ◽  
Strong Staining ◽  
Yolk Sac Cells

1. Quantitative estimations and histological methods have been used to determine the presence and distribution of glycogen in fertilized salmon eggs and subsequent stages of development. 2. A check upon the occurrence of glycogen in each sample was obtained by the use of amylase and the presence of glucose as a result of this technique confirmed, in certain large samples, by the formation of phenylglucosazone crystals. 3. Results of estimations agree with the general distribution of glycogen as shown in histological sections. They differ from those of Hayes & Hollett (1940) who, using water extraction, found no glycogen in stages corresponding to stages I and II and only recorded it as doubtfully present in the yolk-sac. 4. In stages I and II glycogen is concentrated in the blastoderm and perivitelline space. Later the main sources are the muscles, liver and yolk-sac envelope. 5. Glycogen is present in embryonic muscle tissue when fibrils are being laid down (stage III). Subsequently it occurs in both sarcoplasm and muscle fibres. 6. Eight days before hatching (stage V) there is strong staining reaction for glycogen in liver cells, and it is present in all later stages. This glycogen is not obtained from engulfed food or from direct absorption of yolk by liver cells. 7. There is histological evidence that yolk is taken up by the yolk-sac blood vessels after absorption by the yolk-sac cells and dermis. This absorption is accompanied by the appearance of glycogen in these cells and in yolk lying adjacent to them. 8. An increase in amounts of glycogen in both embryo and yolk-sac coincides with a rapid absorption of fat which takes place about 20 days after hatching. 9. The presence of glycogen in blastoderm cells, before the gastrula stage, is similar to the condition in developing Aves and Amphibia. This is true, also, for its appearance early in the formation of muscle tissue. Other similarities are the presence of glycogen in the perivitelline fluid of salmon and Amphibia and the manner of its distribution in the liver of early and late stages of the salmon and chick. 10. There is extra-embryonic glycogen present in the meroblastic eggs of both the salmon and chick. It is concentrated in the embryonic shield of the latter which corresponds, in development, to the glycogen-carrying envelope of the salmon yolk-sac. Accompanying these deposits in both cases is a well-developed circulatory system to assist in the absorption of yolk. 11. The presence of glycogen in the yolk-sac cells of the salmon refutes a suggestion that the embryo receives glucose only by direct diffusion from the yolk. 12. The liver cells and yolk-sac cells overlap in the function of laying down glycogen during development. The latter, therefore, do not form a ‘transitory’ but rather function as a ‘supplementary’ liver, connected with the liver by a venous system until the cells rejoin the true embryo after complete yolk exhaustion.

The development of teratomas from intratesticular grafts of tubal mouse eggs

Development ◽  
1968 ◽  
Vol 20 (3) ◽  
pp. 329-341
Author(s):  
Leroy C. Stevens
Keyword(s):  
Anterior Chamber ◽  
Inbred Mice ◽  
Germ Layers ◽  
Embryonic Tissues ◽  
Embryonic Shield ◽  
Mouse Eggs

Grafts of cleaving tubal ova from non-inbred mice to ectopic sites usually result in growths composed of extra-embryonic but not embryonic tissues (Fawcett, Wisloki & Waldo, 1947; Fawcett, 1950; Jones, 1951; Whitten 1958; Kirby, 1960, 1962a; Billington, 1965; and others). Runner (1947) grafted tubal mouse ova to the anterior chamber of the eye and one developed the three primary germ layers and then regressed, probably because the host and donor were histo-incompatible. This is the only report of an ectopically grafted pre-uterine egg that developed intra-embryonic derivatives. Kirby (1962b, 1965) grafted oviducal segmenting mouse eggs to the kidney and obtained only trophoblast and extra-embryonic membranes. He concluded that a ‘uterine factor’ is necessary for the development of intra-embryonic structures from mouse eggs. Kirby (1965) and Billington (1965) grafted morulae and blastocysts to the testis, and the morulae never gave rise to embryonic shield derivatives.

Early onset of embryonic mortality in sub-fertile families of rainbow trout (Oncorhynchus mykiss)

2005 ◽  
Vol 17 (8) ◽  
pp. 785 ◽  
Author(s):  
J. W. Stoddard ◽  
J. E. Parsons ◽  
J. J. Nagler
Keyword(s):  
Rainbow Trout ◽  
Embryonic Development ◽  
Oncorhynchus Mykiss ◽  
Embryonic Mortality ◽  
Early Embryonic Development ◽  
Single Pair ◽  
Critical Periods ◽  
Embryo Viability ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Embryonic Shield

Survival during early embryonic development is highly variable in oviparous fishes and appears to be related to events associated with the female at the time of ovulation and spawning. The goal of this study was to identify critical periods of mortality associated with early embryonic development in egg batches from female rainbow trout (Oncorhynchus mykiss) that were checked for ovulation every 5–7 days. The experiment was designed to specifically remove post-ovulatory ageing and reduce paternal variability. Embryo viability in 269 single-pair-mated families was systematically tracked at the following five stages: second cleavage (0.5 days post fertilisation (dpf)), elevated blastula (2.5 dpf), embryonic shield (6 dpf), embryonic keel (9 dpf), and retinal pigmentation (19 dpf). At each of the five stages families with embryo viability assessments of <80% were classed as sub-fertile, whereas those with >80% embryo viability were classed as fertile. Embryo viability in sub-fertile families was distinctly reduced at 0.5 dpf, in contrast to fertile families, but remained constant from that point through to 19 dpf. These results suggest that the critical period of early embryonic mortality in sub-fertile families of rainbow trout parallels events that occur at or shortly after fertilisation and is independent of post-ovulatory aging.

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