Frog Development
Introduction
The frog has been historically been used as an amphibian animal model of development due to the ease of observation from the fertilized egg through to tadpole stage. The later metamorphosis of the tadpole to frog has also been studied for hormonal controls and limb development. There have also been many different species used in these developmental studies.
The frog was historically used by many of the early embryology investigators and currently there are many different molecular mechanisms concerning development of the frog. The 2012 Nobel prize in medicine was recently awarded to John Gurdon for his 1960's experiments involving nuclear transplantation with adult nuclei into frog eggs, these studies were the precursor to current research in stem cells.
The African clawed frog (Xenopus laevis) has been used in many embryological and electrophysiological studies as well as the basis of a historic pregnancy test. The advantages of this frog is the fertility cycle can be easliy controlled and the eggs develop entirely independently and easily visible to the investigator. You can see an overview of the frog life cycle with links to specific stages as well as movies of the early process of gastrulation. This animal model has also shown that localization of maternal messenger RNA (eg vegetal and review) appears to play a key role in the development of early embryological patterns.
The Leopard frog (Rana pipiens) in 1952 became the first successful nuclear transfer experiment. Nuclear transfer is an embryological technique, and involves removal of the nucleus from an egg and replacement with the nucleus of another donor cell. This experiment paved the way for what we know today as the field of cloning.[1]
In Australia, the cane toad (Bufo marinus) species was introduced in 1935 to control cane insect pests. It has now itself become an introduced pest and has also been studied/used more in order to try and biologically control. The area which they occupy has continued to expand. This toad has a poisonous secretion that is extremely toxic and should be handled with care at all times.
Some Recent Findings
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Recent References | References
Taxon
Xenopus Laevis
Eukaryotae; mitochondrial eukaryotes; Metazoa; Chordata;Vertebrata; Amphibia; Batrachia; Anura; Mesobatrachia; Pipoidea;Pipidae; Xenopodinae; Xenopus
Rana pipiens
Taxonomy Id: 8404 Preferred common name: northern leopard frog Rank: species
Genetic code: Translation table 1 (Standard) Mitochondrial genetic code: Translation table 2 Lineage( abbreviated ):
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Amphibia; Batrachia; Anura; Neobatrachia; Ranoidea; Ranidae; Raninae; Rana
Frog Life Cycle
Development Timeline
Typical frog development at 18oC from fertilised egg.
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Stages in the Normal Development of Rana pipiens
</gallery> File:Rugh 011.jpg|Stages in the Normal Development of Rana pipiens. File:Rugh 012.jpg|Stages in the Normal Development of Rana pipiens. File:Rugh 013.jpg|Stages in the Normal Development of Rana pipiens. </gallery>
Oocyte Balbiani body
- spherical cytoplasmic region that forms within the oocyte in early oogenesis and then fragments and disperses in late oogenesis.
- membrane-less structure consisting of mitochondria, endoplasmic reticulum (ER), membranous vesicles and lipid droplets.
Xenopus stage I oocytes
- Balbiani body is ∼40 μm in diameter
- contains half a million mitochondria, with different morphology and metabolism from other cytoplasmic mitochondria
- rich in membranous vesicles, and ER cysternae.
- vegetal apex (METRO region) contains germinal granules and localized RNAs
- Xlsirts[7]
- family of interspersed repeat RNAs that contain from 3 to 13 repeat units (each 79 to 81 nucleotides long) flanked by unique sequences.
- homologous to the mammalian Xist gene involved in X chromosome inactivation
- stage 2 oocytes - appears first in the mitochondrial cloud (Balbiani body)
- stage 3 oocytes - translocated as island-like structures to the vegetal cortex coincident with the localization of the germ plasm.
Germ Layers
The following paper cartoons[8] show models of signaling mechanisms that occur during early development of the germ cell layers (ectoderm, mesoderm and endoderm).
Neural
Comparative brain anatomy frog and dog models.
Xenbase
Xenbase is a Xenopus model organism computer database with 4 GB of data in many hundreds of tables that has recently (2012) been updated, as described in the abstract of an NAR article.[9]
- "Xenbase (http://www.xenbase.org) is a model organism database that provides genomic, molecular, cellular and developmental biology content to biomedical researchers working with the frog, Xenopus and Xenopus data to workers using other model organisms. As an amphibian Xenopus serves as a useful evolutionary bridge between invertebrates and more complex vertebrates such as birds and mammals. Xenbase content is collated from a variety of external sources using automated and semi-automated pipelines then processed via a combination of automated and manual annotation. A link-matching system allows for the wide variety of synonyms used to describe biological data on unique features, such as a gene or an anatomical entity, to be used by the database in an equivalent manner. Recent updates to the database include the Xenopus laevis genome, a new Xenopus tropicalis genome build, epigenomic data, collections of RNA and protein sequences associated with genes, more powerful gene expression searches, a community and curated wiki, an extensive set of manually annotated gene expression patterns and a new database module that contains data on over 700 antibodies that are useful for exploring Xenopus cell and developmental biology."
Historic Researchers
Wilhelm Roux (1850 – 1924) | Hans Spemann (1869 - 1941) | John Gurdon (1933 - ) |
A German zoologist and pioneer of experimental embryology. Experimented by pricking and destroying one of the two blastomeres, to obtain half an embryo from the other. | A German embryologist who worked extensively on amphibian development and was the discoverer of the organiser region (or primitive node) the controller of gastrulation. Received the 1935 Nobel Prize in Physiology or Medicine "for his discovery of the organizer effect in embryonic development". | An English embryologist in 1962 used nuclear transplantation and cloning to show that the nucleus of a differentiated somatic cell retains the totipotency necessary to form a whole organism. Received the 2012 Nobel Prize "for the discovery that mature cells can be reprogrammed to become pluripotent". |
References
,
- ↑ <pubmed>16589125</pubmed>| PMC1063586 | PNAS Classic
- ↑ <pubmed>19549299</pubmed>| PMC2706234 | BMC Dev Biol.
- ↑ <pubmed>23184997</pubmed>
- ↑ <pubmed>22195698</pubmed>
- ↑ <pubmed>21042572</pubmed>
- ↑ <pubmed>20110330</pubmed>
- ↑ <pubmed>7505061</pubmed>
- ↑ <pubmed>17925852</pubmed>| PMC1994590 | PLoS ONE
- ↑ <pubmed>23125366 </pubmed>
Books
Rugh, R. The Frog Its Reproduction and Development The Blakiston Company, New York, 1951.
Search Pubmed: frog development | xenopus development
Additional Images
Historic Images |
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Bailey, F.R. and Miller, A.M. (1921). Text-Book of Embryology. Early development of the frog |
External Links
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
- Xenbase A database of information pertaining to the cell and developmental biology of the frog, Xenopus
- Xenopus Laboratory List A database of Labs studying Xenopus
- Xenopus Microarrays
- Xenopus Cell Biology
- The Xenopus Molecular Marker Resource An electronic library of information on embryonic development of the frog, Xenopus laevis | Index page for all Markers | whole mount staining patterns
- Molecular Markers of Development: cement gland XA, XAG, XCG | early mesoderm - BMP2, BMP4, Chordin, goosecoid, Mix,[Marker_pages/organizer/noggin.html noggin], Xbra, Xnr3, Xwnt-8, XVent1 and XVent2 | endothelial - Xl-fli | germ cells - Xpat | heart - cardiac troponin I , XNKX-2.5, XTin1 (XNKX-2.3) | lateral line - tor70, [Marker_pages/CNS/2G9.html 2G9] | muscle - 5A3, 12/101, cardiac actin, XMyf-5, XMyoD | neural crest - Slug, XTwist , xAP2 | notochord - Xnot, tor70 | pronephros - [Marker_pages/pronephros/3G8.html 3G8 ], Wilms' tumor (xWT1), Xlim-1, Xwnt-4 | pronephric duct - 4A6
- Frogs of Greater Brisbane Region (Australia)
- Developmental Biology- Laurie Iten's Serially Sectioned Frog and Chick Embryos
- Developmental Biology- Jeff Hardin's Amphibian Embryology Tutorial
- NIH- Organisms for biomedical research
- Columbia University Kelley Lab - The natural and unnatural histories of xenopus laevis
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Cite this page: Hill, M.A. (2024, June 14) Embryology Frog Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Frog_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G