Platypus Development

Introduction

Platypus, 1840 Cyclopaedia

The platypus (Ornithorhynchus anatinus) also called the "duck-billed platypus" together with the 2 echidna groups (short-beaked and long-beaked) are the only 3 surviving genera of the order Monotremata.

The platypus is a unique egg-laying mammal and is not a common animal model of mammalian embryonic development. It lives in freshwater stream systems and is also the only known mammal that produces venom.

The platypus genome has also been recently sequenced 17495919 18464734.

Why platypus? Greek Platus = flat or broad, and pous = foot.

Links: Echidna | Koala | Platypus | Category:Platypus

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Animal Development: Axolotl | Bat | Cat | Chicken | Cow | Dog | Dolphin | Echidna | Fly | Frog | Grasshopper | Guinea Pig | Hamster | Kangaroo | Koala | Lizard | Medaka | Mouse | Pig | Platypus | Rabbit | Rat | Sea Squirt | Sea Urchin | Sheep | Worm | Zebrafish | Life Cycles

Some Recent Findings

Distinct development of the cerebral cortex in platypus and echidna "Both lineages of the modern monotremes have distinctive features in the cerebral cortex, but the developmental mechanisms that produce such different adult cortical architecture remain unknown. Similarly, nothing is known about the differences and/or similarities between monotreme and therian cortical development. We have used material from the Hill embryological collection to try to answer key questions concerning cortical development in monotremes. Our findings indicate that gyrencephaly begins to emerge in the echidna brain shortly before birth (crown-rump length 12.5 mm), whereas the cortex of the platypus remains lissencephalic throughout development." Sex Determination - ATRX, DMRT1, DMRT7 and WT1 "One of the most puzzling aspects of monotreme reproductive biology is how they determine sex in the absence of the SRY gene that triggers testis development in most other mammals. Although monotremes share a XX female/XY male sex chromosome system with other mammals, their sex chromosomes show homology to the chicken Z chromosome, including the DMRT1 gene, which is a dosage-dependent sex determination gene in birds. ... We show that these four genes in the adult platypus have the same expression pattern as in other mammals, suggesting that they have a conserved role in sexual development independent of genomic location." Mammalian Diversity "... Monotremes are remarkable because these mammals are born from eggs laid outside of the mother's body. Marsupial mammals have relatively short gestation periods and give birth to highly altricial young that continue a significant amount of "fetal" development after birth, supported by a highly sophisticated lactation. Less than 10% of mammalian species are monotremes or marsupials, so the great majority of mammals are grouped into the subclass Eutheria, including mouse and human." How did the platypus get its sex chromosome chain? "... Its chromosome complement is no less extraordinary, for it includes a system in which ten sex chromosomes form an extensive meiotic chain in males. Such meiotic multiples are unprecedented in vertebrates but occur sporadically in plant and invertebrate species."

More recent papers

This table shows an automated computer PubMed search using the listed sub-heading term. Therefore the list of references do not reflect any editorial selection of material based on content or relevance. References appear in this list based upon the date of the actual page viewing. References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability. Links: References | Discussion Page | Pubmed Most Recent Search term: Platypus Embryology Kenta Sumiyama, Tsutomu Miyake, Jane Grimwood, Andrew Stuart, Mark Dickson, Jeremy Schmutz, Frank H Ruddle, Richard M Myers, Chris T Amemiya Theria-specific homeodomain and cis-regulatory element evolution of the Dlx3-4 bigene cluster in 12 different mammalian species. J. Exp. Zool. B Mol. Dev. Evol.: 2012, 318(8);639-50 PMID:22951979 Ken W S Ashwell, Craig D Hardman Distinct development of the trigeminal sensory nuclei in platypus and echidna. Brain Behav. Evol.: 2012, 79(4);261-74 PMID:22722086 Ken W S Ashwell Development of the cerebellum in the platypus (Ornithorhynchus anatinus) and short-beaked echidna (Tachyglossus aculeatus). Brain Behav. Evol.: 2012, 79(4);237-51 PMID:22572119 Ken W S Ashwell Development of the hypothalamus and pituitary in platypus (Ornithorhynchus anatinus) and short-beaked echidna (Tachyglossus aculeatus). J. Anat.: 2012, 221(1);9-20 PMID:22512474 Ken W S Ashwell Development of the spinal cord and peripheral nervous system in platypus (Ornithorhynchus anatinus) and short-beaked echidna (Tachyglossus aculeatus). Somatosens Mot Res: 2012, 29(1);13-27 PMID:22401666

Taxon

Ornithorhynchus anatinus Lineage( full ) cellular organisms; Eukaryota; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Prototheria; Monotremata; Ornithorhynchidae; Ornithorhynchus

Development Overview

Platypus mate in July to October, eggs are laid about one month later, eggs hatch and young suckle from their mother, emerging from the burrow in late January to early March.

Gestation is about 2-4 weeks (not exactly known) female lays lays usually 2 (sometimes 3) soft-shelled eggs.

Egg Development after laying, incubation approximately 6 - 10 days.

intrauterine has a major axis (approximately 17mm) and contains neurula-stage (19-20 somite) embryo with prominent trigeminal ganglion (CN 5) primordia. The embryo at this stage is in a period of rapid modelling of the major early organ primordia of the nervous system, cardiovascular system, excretory system, and somite-derived components of the body wall.

after laying five primary brain vesicles, cranial ganglia (CN5, CN7, CN8, CN9, CN10, CN11 and CN12). Alimentary system has an expanded stomach, pancreatic primordia and a gall bladder.

somitogenesis faster than in humans

Just Before Hatching- upturned snout (contains an oscaruncle and a sharp recurved median egg tooth, for shell removal). Forelimbs (pronated with separate digits with claw primordia).

Hatching- forelimbs with clawed digits and hindlimbs are still paddles with digital rays. A prominent yolk-sac navel is present.

Post-Hatching- (external features from day 0 to 6 months old) development of bill and webbing of the forefeet. Many features show similarities to marsupials (though different in both timing and morphology). (Note- exact age of the specimens relies on ages given to specimens at time of collection)

Young- feed on milk from mother and live in a river burrow for 3 - 4 months.

Differences between Platypus and Human- platypus rate of somitogenesis faster and size of early platypus embryonal area is larger, extra-embryonic membranes have unique morphology and function.

(Data/text above modified from (Hughes Hughes RL and Hall LS, 1998; Manger Manger PR, Hall LS, Pettigrew JD, 1998 and other sources)

Gastrointestinal Tract

A recent study has identified differences in the gastrointestinal tract digestive enzymes secreted. Note that in humans parietal cells produce gastric intrinsic factor, but this is produced in the pancreas of monotremes and other mammals.

Cardiovascular

Platypus ventricular septum

Heart conduction system species comparison: Bird, Monotreme and Placental

Genome

The platypus karyotype (2 n = 52) consists of 21 autosomes and 10 sex chromosomes (5X's and 5Y's in male and 5 X-pairs in female).

Emergence of traits along the mammalian lineage.

The platypus mitochondrial genome was sequenced in 1994.

The nuclear genome first draft sequence was released in 2008.

"This monotreme exhibits a fascinating combination of reptilian and mammalian characters. For example, platypuses have a coat of fur adapted to an aquatic lifestyle; platypus females lactate, yet lay eggs; and males are equipped with venom similar to that of reptiles. Analysis of the first monotreme genome aligned these features with genetic innovations. We find that reptile and platypus venom proteins have been co-opted independently from the same gene families; milk protein genes are conserved despite platypuses laying eggs; and immune gene family expansions are directly related to platypus biology."

Genetic Divergence

This graph shows the phylogeny and divergence timescales of mammalian species using the dentin phosphoprotein (DPP) gene sequence comparison. Note the early timescale divergence of the platypus species relative to the other mammalian species.

Sex Chromosomes

The total diploid number of chromosomes is n=52 and in the males ten sex chromosomes form an extensive meiotic chain.

Five male-specific chromosomes (Y chromosomes) and five chromosomes present in one copy in males and two copies in females (X chromosomes) These ten chromosomes form a multivalent chain at male meiosis, adopting an alternating pattern to segregate into XXXXX-bearing and YYYYY-bearing sperm. .

Spermatozoa Development

• monotreme spermatozoa undergo some post-testicular maturational changes
  • acquisition of progressive motility
  • loss of cytoplasmic droplets
  • aggregation of single spermatozoa into bundles during passage through the epididymis
• epididymis of monotremes is not adapted for sperm storage
  • absence of platypus genes for the epididymal-specific proteins
  • most abundant secreted protein in the platypus epididymis is a lipocalin (homologues are the most secreted proteins in the reptilian epididymis).
  • lipocalins are a group of extracellular proteins able to bind lipophiles by enclosure within their structures and minimizing solvent contact.

Information based on

Immune System

For details read the recent article.

• Monotremes have IgM, IgG, IgA and IgE
• do not use IgY
• has multiple Ig heavy chain subclasses
• at least two IgG and two IgA sub-isotypes

References

Reviews

R L Hughes, L S Hall Early development and embryology of the platypus. Philos. Trans. R. Soc. Lond., B, Biol. Sci.: 1998, 353(1372);1101-14 PMID:9720108

P R Manger, L S Hall, J D Pettigrew The development of the external features of the platypus (Ornithorhynchus anatinus). Philos. Trans. R. Soc. Lond., B, Biol. Sci.: 1998, 353(1372);1115-25 PMID:9720109

R L Hughes Monotreme development with particular reference to the extraembryonic membranes. J. Exp. Zool.: 1993, 266(6);480-94 PMID:8371093

Articles

Ken W S Ashwell, Craig D Hardman Distinct development of the trigeminal sensory nuclei in platypus and echidna. Brain Behav. Evol.: 2012, 79(4);261-74 PMID:22722086

Wesley C Warren, LaDeana W Hillier, Jennifer A Marshall Graves, Ewan Birney, Chris P Ponting, Frank Grützner, Katherine Belov, Webb Miller, Laura Clarke, Asif T Chinwalla, Shiaw-Pyng Yang, Andreas Heger, Devin P Locke, Pat Miethke, Paul D Waters, Frédéric Veyrunes, Lucinda Fulton, Bob Fulton, Tina Graves, John Wallis, Xose S Puente, Carlos López-Otín, Gonzalo R Ordóñez, Evan E Eichler, Lin Chen, Ze Cheng, Janine E Deakin, Amber Alsop, Katherine Thompson, Patrick Kirby, Anthony T Papenfuss, Matthew J Wakefield, Tsviya Olender, Doron Lancet, Gavin A Huttley, Arian F A Smit, Andrew Pask, Peter Temple-Smith, Mark A Batzer, Jerilyn A Walker, Miriam K Konkel, Robert S Harris, Camilla M Whittington, Emily S W Wong, Neil J Gemmell, Emmanuel Buschiazzo, Iris M Vargas Jentzsch, Angelika Merkel, Juergen Schmitz, Anja Zemann, Gennady Churakov, Jan Ole Kriegs, Juergen Brosius, Elizabeth P Murchison, Ravi Sachidanandam, Carly Smith, Gregory J Hannon, Enkhjargal Tsend-Ayush, Daniel McMillan, Rosalind Attenborough, Willem Rens, Malcolm Ferguson-Smith, Christophe M Lefèvre, Julie A Sharp, Kevin R Nicholas, David A Ray, Michael Kube, Richard Reinhardt, Thomas H Pringle, James Taylor, Russell C Jones, Brett Nixon, Jean-Louis Dacheux, Hitoshi Niwa, Yoko Sekita, Xiaoqiu Huang, Alexander Stark, Pouya Kheradpour, Manolis Kellis, Paul Flicek, Yuan Chen, Caleb Webber, Ross Hardison, Joanne Nelson, Kym Hallsworth-Pepin, Kim Delehaunty, Chris Markovic, Pat Minx, Yucheng Feng, Colin Kremitzki, Makedonka Mitreva, Jarret Glasscock, Todd Wylie, Patricia Wohldmann, Prathapan Thiru, Michael N Nhan, Craig S Pohl, Scott M Smith, Shunfeng Hou, Mikhail Nefedov, Pieter J de Jong, Marilyn B Renfree, Elaine R Mardis, Richard K Wilson Genome analysis of the platypus reveals unique signatures of evolution. Nature: 2008, 453(7192);175-83 PMID:18464734

Ken W S Ashwell Cyto- and chemoarchitecture of the monotreme olfactory tubercle. Brain Behav. Evol.: 2006, 67(2);85-102 PMID:16244467

Willem Rens, Frank Grützner, Patricia C M O'brien, Helen Fairclough, Jennifer A M Graves, Malcolm A Ferguson-Smith Resolution and evolution of the duck-billed platypus karyotype with an X1Y1X2Y2X3Y3X4Y4X5Y5 male sex chromosome constitution. Proc. Natl. Acad. Sci. U.S.A.: 2004, 101(46);16257-61 PMID:15534209

F Davies The Conducting System of the Monotreme Heart. J. Anat.: 1931, 65(Pt 3);339-51 PMID:17104326

Books

• Platypus: The Extraordinary Story of How a Curious Creature Baffled the World (Hardcover) by Ann Moyal (Amazon Link)
• Platypus (Mondo Animals) (Paperback) by Joan Short, Jack Green, Bettina Bird, Andrew Wichlinski (Illustrator) (Amazon Link)

Search PubMed

Search Feb2006 "Platypus development" 303 reference articles of which 5 were reviews.

Search PubMed: Platypus development | monotreme development

Additional Images

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  Platypus chemosensory receptor gene repertoire

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.

• Australian Platypus Conservancy Platypus Fact File | Platypus Historical Background
• Access Excellence The National Health Museum (USA) Australian Mammals: Evolutionary Development as a Result of Geographic Isolation
• University of Michigan Animal Diversity Web monotremes
• University of California, Davis Leah Krubitzer | Krubitzer Lab
• University of Texas, Austin Digital Morphology Skull images and movies
• NCBI Genome Project Ornithorhynchus anatinus (duck-billed platypus)
• BBC Wildfacts Platypus
• http://www.platypus.org.uk/
• Reproduction, Fertility and Development Volume 21 Number 8 2009 Beyond the Platypus Genome
• Tasmania - Department of Primary Industries, Parks, Water and Environment Platypus: Introduction to an Iconic Mammal

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What Links Here?

Cite this page:

Hill, M.A. (2013) Platypus Development. Retrieved June 18, 2013, from http://php.med.unsw.edu.au/embryology/index.php?title=Platypus_Development

Dr Mark Hill 2013, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G