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
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Search term: Platypus Embryology
Ken W S Ashwell, Boaz Shulruf Vestibular development in marsupials and monotremes. J. Anat.: 2014, 224(4);447-58 PubMed 24298911
Lutz Langbein, Julia Reichelt, Leopold Eckhart, Silke Praetzel-Wunder, Walter Kittstein, Nikolaus Gassler, Juergen Schweizer New facets of keratin K77: interspecies variations of expression and different intracellular location in embryonic and adult skin of humans and mice. Cell Tissue Res.: 2013, 354(3);793-812 PubMed 24057875
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 PubMed 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 PubMed 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 PubMed 22572119
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
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)
|| A 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.
Platypus ventricular septum
Heart conduction system species comparison: Bird, Monotreme and Placental
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."
|| 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.
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. .
- 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 this study.
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
- ↑ Mikkelsen TS, Wakefield MJ, Aken B, Amemiya CT, Chang JL, Duke S, Garber M, Gentles AJ, Goodstadt L, Heger A, Jurka J, Kamal M, Mauceli E, Searle SM, Sharpe T, Baker ML, Batzer MA, Benos PV, Belov K, Clamp M, Cook A, Cuff J, Das R, Davidow L, Deakin JE, Fazzari MJ, Glass JL, Grabherr M, Greally JM, Gu W, Hore TA, Huttley GA, Kleber M, Jirtle RL, Koina E, Lee JT, Mahony S, Marra MA, Miller RD, Nicholls RD, Oda M, Papenfuss AT, Parra ZE, Pollock DD, Ray DA, Schein JE, Speed TP, Thompson K, VandeBerg JL, Wade CM, Walker JA, Waters PD, Webber C, Weidman JR, Xie X, Zody MC, Graves JA, Ponting CP, Breen M, Samollow PB, Lander ES & Lindblad-Toh K. (2007). Genome of the marsupial Monodelphis domestica reveals innovation in non-coding sequences. Nature , 447, 167-77. PMID: 17495919 DOI.
- ↑ 2.0 2.1 2.2 2.3 Warren WC, Hillier LW, Marshall Graves JA, Birney E, Ponting CP, Grützner F, Belov K, Miller W, Clarke L, Chinwalla AT, Yang SP, Heger A, Locke DP, Miethke P, Waters PD, Veyrunes F, Fulton L, Fulton B, Graves T, Wallis J, Puente XS, López-Otín C, Ordóñez GR, Eichler EE, Chen L, Cheng Z, Deakin JE, Alsop A, Thompson K, Kirby P, Papenfuss AT, Wakefield MJ, Olender T, Lancet D, Huttley GA, Smit AF, Pask A, Temple-Smith P, Batzer MA, Walker JA, Konkel MK, Harris RS, Whittington CM, Wong ES, Gemmell NJ, Buschiazzo E, Vargas Jentzsch IM, Merkel A, Schmitz J, Zemann A, Churakov G, Kriegs JO, Brosius J, Murchison EP, Sachidanandam R, Smith C, Hannon GJ, Tsend-Ayush E, McMillan D, Attenborough R, Rens W, Ferguson-Smith M, Lefèvre CM, Sharp JA, Nicholas KR, Ray DA, Kube M, Reinhardt R, Pringle TH, Taylor J, Jones RC, Nixon B, Dacheux JL, Niwa H, Sekita Y, Huang X, Stark A, Kheradpour P, Kellis M, Flicek P, Chen Y, Webber C, Hardison R, Nelson J, Hallsworth-Pepin K, Delehaunty K, Markovic C, Minx P, Feng Y, Kremitzki C, Mitreva M, Glasscock J, Wylie T, Wohldmann P, Thiru P, Nhan MN, Pohl CS, Smith SM, Hou S, Nefedov M, de Jong PJ, Renfree MB, Mardis ER & Wilson RK. (2008). Genome analysis of the platypus reveals unique signatures of evolution. Nature , 453, 175-83. PMID: 18464734 DOI.
- ↑ Ashwell KW & Hardman CD. (2012). Distinct development of the cerebral cortex in platypus and echidna. Brain Behav. Evol. , 79, 57-72. PMID: 22143038 DOI.
- ↑ Tsend-Ayush E, Lim SL, Pask AJ, Hamdan DD, Renfree MB & Grützner F. (2009). Characterisation of ATRX, DMRT1, DMRT7 and WT1 in the platypus (Ornithorhynchus anatinus). Reprod. Fertil. Dev. , 21, 985-91. PMID: 19874722 DOI.
- ↑ Behringer RR, Eakin GS & Renfree MB. (2006). Mammalian diversity: gametes, embryos and reproduction. Reprod. Fertil. Dev. , 18, 99-107. PMID: 16478607
- ↑ 6.0 6.1 Gruetzner F, Ashley T, Rowell DM & Marshall Graves JA. (2006). How did the platypus get its sex chromosome chain? A comparison of meiotic multiples and sex chromosomes in plants and animals. Chromosoma , 115, 75-88. PMID: 16344965 DOI.
- ↑ Ordoñez GR, Hillier LW, Warren WC, Grützner F, López-Otín C & Puente XS. (2008). Loss of genes implicated in gastric function during platypus evolution. Genome Biol. , 9, R81. PMID: 18482448 DOI.
- ↑ Davies F. (1931). The Conducting System of the Monotreme Heart. J. Anat. , 65, 339-51. PMID: 17104326
- ↑ Edwards CA, Rens W, Clarke O, Mungall AJ, Hore T, Graves JA, Dunham I, Ferguson-Smith AC & Ferguson-Smith MA. (2007). The evolution of imprinting: chromosomal mapping of orthologues of mammalian imprinted domains in monotreme and marsupial mammals. BMC Evol. Biol. , 7, 157. PMID: 17822525 DOI.
N J Gemmell, A Janke, P S Western, J M Watson, S Pääbo, J A Graves Cloning and characterization of the platypus mitochondrial genome. J. Mol. Evol.: 1994, 39(2);200-5 PubMed 7932783
- ↑ McKnight DA & Fisher LW. (2009). Molecular evolution of dentin phosphoprotein among toothed and toothless animals. BMC Evol. Biol. , 9, 299. PMID: 20030824 DOI.
- ↑ Belov K & Hellman L. (2003). Immunoglobulin genetics of Ornithorhynchus anatinus (platypus) and Tachyglossus aculeatus (short-beaked echidna). Comp. Biochem. Physiol., Part A Mol. Integr. Physiol. , 136, 811-9. PMID: 14667846
Hughes RL & Hall LS. (1998). Early development and embryology of the platypus. Philos. Trans. R. Soc. Lond., B, Biol. Sci. , 353, 1101-14. PMID: 9720108 DOI.
Manger PR, Hall LS & Pettigrew JD. (1998). The development of the external features of the platypus (Ornithorhynchus anatinus). Philos. Trans. R. Soc. Lond., B, Biol. Sci. , 353, 1115-25. PMID: 9720109 DOI.
Hughes RL. (1993). Monotreme development with particular reference to the extraembryonic membranes. J. Exp. Zool. , 266, 480-94. PMID: 8371093 DOI.
Ashwell KW & Hardman CD. (2012). Distinct development of the trigeminal sensory nuclei in platypus and echidna. Brain Behav. Evol. , 79, 261-74. PMID: 22722086 DOI.
Warren WC, Hillier LW, Marshall Graves JA, Birney E, Ponting CP, Grützner F, Belov K, Miller W, Clarke L, Chinwalla AT, Yang SP, Heger A, Locke DP, Miethke P, Waters PD, Veyrunes F, Fulton L, Fulton B, Graves T, Wallis J, Puente XS, López-Otín C, Ordóñez GR, Eichler EE, Chen L, Cheng Z, Deakin JE, Alsop A, Thompson K, Kirby P, Papenfuss AT, Wakefield MJ, Olender T, Lancet D, Huttley GA, Smit AF, Pask A, Temple-Smith P, Batzer MA, Walker JA, Konkel MK, Harris RS, Whittington CM, Wong ES, Gemmell NJ, Buschiazzo E, Vargas Jentzsch IM, Merkel A, Schmitz J, Zemann A, Churakov G, Kriegs JO, Brosius J, Murchison EP, Sachidanandam R, Smith C, Hannon GJ, Tsend-Ayush E, McMillan D, Attenborough R, Rens W, Ferguson-Smith M, Lefèvre CM, Sharp JA, Nicholas KR, Ray DA, Kube M, Reinhardt R, Pringle TH, Taylor J, Jones RC, Nixon B, Dacheux JL, Niwa H, Sekita Y, Huang X, Stark A, Kheradpour P, Kellis M, Flicek P, Chen Y, Webber C, Hardison R, Nelson J, Hallsworth-Pepin K, Delehaunty K, Markovic C, Minx P, Feng Y, Kremitzki C, Mitreva M, Glasscock J, Wylie T, Wohldmann P, Thiru P, Nhan MN, Pohl CS, Smith SM, Hou S, Nefedov M, de Jong PJ, Renfree MB, Mardis ER & Wilson RK. (2008). Genome analysis of the platypus reveals unique signatures of evolution. Nature , 453, 175-83. PMID: 18464734 DOI.
Ashwell KW. (2006). Cyto- and chemoarchitecture of the monotreme olfactory tubercle. Brain Behav. Evol. , 67, 85-102. PMID: 16244467 DOI.
Rens W, Grützner F, O'brien PC, Fairclough H, Graves JA & Ferguson-Smith MA. (2004). Resolution and evolution of the duck-billed platypus karyotype with an X1Y1X2Y2X3Y3X4Y4X5Y5 male sex chromosome constitution. Proc. Natl. Acad. Sci. U.S.A. , 101, 16257-61. PMID: 15534209 DOI.
Davies F. (1931). The Conducting System of the Monotreme Heart. J. Anat. , 65, 339-51. PMID: 17104326
- 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 Feb2006 "Platypus development" 303 reference articles of which 5 were reviews.
Search PubMed: Platypus development | monotreme development
Platypus chemosensory receptor gene repertoire
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