Kangaroo Development

From Embryology

Introduction

Red-necked wallaby

Macropodid marsupial have short five digit forelimbs and large four digit hindlimbs specially adapted for hopping. The hindlimb digits differ from mammals by a missing digit 1, fused digits 2 and 3 and an elongated digit 4.

Some Recent Findings

  • The tammar wallaby genome and transcriptome A cross-journal collection of articles from the tammar wallaby genome and transcriptome sequencing project. BMC Genomics
  • Desert hedgehog is a mammal-specific gene expressed during testicular and ovarian development in a marsupial.[1] "These data suggest that there is a highly conserved role for DHH signalling in the differentiation and function of the mammalian testis and that DHH may be necessary for marsupial ovarian development. The receptors PTCH1 and PTCH2 are highly conserved mediators of hedgehog signalling in both the developing and adult marsupial gonads. Together these findings indicate DHH is an essential therian mammal-specific morphogen in gonadal development and gametogenesis."
  • Developmental origins of precocial forelimbs in marsupial neonates[2] "We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development. The genome has been sequenced to 2x coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements."

Taxon

Taxonomy ID: 9322

Genbank common name: kangaroo

Inherited blast name: marsupials

Rank: species

Genetic code: Translation table 1 (Standard)

Mitochondrial genetic code: Translation table 2 (Vertebrate Mitochondrial)

Lineage ( full )

cellular organisms; Eukaryota; Opisthokonta; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Theria; Metatheria; Diprotodontia; Macropodidae; Macropus

Links: Taxonomy Browser Macropus

Development Overview

  • short pregnancy period
  • pregnancy can be maternally delayed (diapause) at blastocyst stage
  • born in altricial (underdeveloped) state
  • development continues attached to a teat in the pouch
  • during pouch period growth controlled by milk composition changes
  • immune system, thyroid and thermoregulation develops after birth

Genome

Tammar wallaby karyotype.jpg

The tammar wallaby karyotype (2 n = 16) consists of 7 autosomes and the two sex chromosomes.[3]

References

  1. <pubmed>22132805 </pubmed>
  2. <pubmed>21854559</pubmed>Genome Biol.
  3. <pubmed>17822525</pubmed>| BMC Evol Biol.

Reviews

<pubmed>18805821</pubmed>


Articles

<pubmed>21672208</pubmed> <pubmed>21540568</pubmed> <pubmed>18431054</pubmed> <pubmed>18322362</pubmed> <pubmed>18069991</pubmed> <pubmed>4791592</pubmed>

Books

  • Life of Marsupials by Hugh Tyndale-Biscoe Publisher: CSIRO Publishing (2005).
  • Kangaroo - A Portrait of an Extraordinary Marsupial by Stephen Jackson and Karl Vernes Publisher: Allen & Unwin (2010).

Search PubMed

Search PubMed: Kangaroo development | Macropus eugenii | marsupial development

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Cite this page: Hill, M.A. (2021, January 24) Embryology Kangaroo Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Kangaroo_Development

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© Dr Mark Hill 2021, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G