Koala Development: Difference between revisions
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[[File:Koala.jpg|thumb|Adult Koala]] | [[File:Koala.jpg|thumb|Adult Koala]] | ||
The koala (''Phascolarctos cinereus'') is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae. | The {{koala}} (''Phascolarctos cinereus'') is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae. | ||
(Greek, ''phaskolos'' = "pouch" and ''arktos'' = "bear"; Latin, ''cinereus'' = "ash-coloured") | (Greek, ''phaskolos'' = "pouch" and ''arktos'' = "bear"; Latin, ''cinereus'' = "ash-coloured") | ||
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* '''Characterisation of the immune compounds in koala milk using a combined transcriptomic and proteomic approach''' | * '''Characterisation of the immune compounds in koala milk using a combined transcriptomic and proteomic approach'''{{#pmid:27713568|PMID27713568}} "Production of milk is a key characteristic of mammals, but the features of lactation vary greatly between monotreme, marsupial and eutherian mammals. Marsupials have a short gestation followed by a long lactation period, and milk constituents vary greatly across lactation. Marsupials are born immunologically naïve and rely on their mother's milk for immunological protection. Koalas (Phascolarctos cinereus) are an iconic Australian species that are increasingly threatened by disease. Here we use a mammary transcriptome, two milk proteomes and the koala genome to comprehensively characterise the protein components of koala milk across lactation, with a focus on immune constituents. The most abundant proteins were well-characterised milk proteins, including β-lactoglobulin and lactotransferrin. In the mammary transcriptome, 851 immune transcripts were expressed, including immunoglobulins and complement components. We identified many abundant antimicrobial peptides, as well as novel proteins with potential antimicrobial roles. We discovered that marsupial VELP is an ortholog of eutherian Glycam1, and likely has an antimicrobial function in milk. We also identified highly-abundant koala endogenous-retrovirus sequences, identifying a potential transmission route from mother to young." | ||
* '''Developmental origins of precocial forelimbs in marsupial neonates'''<ref><pubmed>21098569</pubmed></ref> "Marsupial mammals are born in an embryonic state, as compared with their eutherian counterparts, yet certain features are accelerated. The most conspicuous of these features are the precocial forelimbs, which the newborns use to climb unaided from the opening of the birth canal to the teat. The developmental mechanisms that produce this acceleration are unknown. Here we show that heterochronic and heterotopic changes early in limb development contribute to forelimb acceleration. Using Tbx5 and Tbx4 as fore- and hindlimb field markers, respectively, we have found that, compared with mouse, both limb fields arise notably early during opossum development." | * '''Developmental origins of precocial forelimbs in marsupial neonates'''<ref><pubmed>21098569</pubmed></ref> "Marsupial mammals are born in an embryonic state, as compared with their eutherian counterparts, yet certain features are accelerated. The most conspicuous of these features are the precocial forelimbs, which the newborns use to climb unaided from the opening of the birth canal to the teat. The developmental mechanisms that produce this acceleration are unknown. Here we show that heterochronic and heterotopic changes early in limb development contribute to forelimb acceleration. Using Tbx5 and Tbx4 as fore- and hindlimb field markers, respectively, we have found that, compared with mouse, both limb fields arise notably early during opossum development." |
Revision as of 12:09, 5 May 2018
Embryology - 21 May 2024 Expand to Translate |
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Introduction
The koala (Phascolarctos cinereus) is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae.
(Greek, phaskolos = "pouch" and arktos = "bear"; Latin, cinereus = "ash-coloured")
Australian Animal: echidna | kangaroo | koala | platypus | possum | Category:Echidna | Category:Kangaroo | Category:Koala | Category:Platypus | Category:Possum | Category:Marsupial | Category:Monotreme | Development Timetable | K12 | |||||
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Some Recent Findings
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More recent papers |
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Koala Embryology <pubmed limit=5>Koala Embryology</pubmed> |
Taxon
Taxonomy ID: 38626
Genbank common name: koala 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; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Theria; Metatheria; Diprotodontia; Phascolarctidae; Phascolarctos
Development Overview
- Adults - females reach maturity at 2 to 3 years of age, males at about 3 years of age.[5]
- Joey - a single young produced each year for about 12 years.
- Gestation - approximately 35 days, born under-developed (hairless, blind, and earless). There is a report of extended gestation.[6]
- Birth - joey about 6 mm long crawls into the the mother's downward-facing pouch.
- Pouch Development - joey remain in the pouch for about 6 months attached to one of the two available teats and feeding on milk, complete development.
- Outside of the pouch - joey then begins to explore and to consume small quantities of the mother’s "pap" (thought to come from the mother's cecum) in order to inoculate its gut with the microbes necessary to digest eucalypt leaves.
- Joey will remain with its mother for about another 6 months, riding on her back, and feeding on both milk and eucalypt leaves until weaning is complete at about 12 months of age.
System Development
The marsupial neonate at birth has a variation between the degree of development of different systems.[7]
- well-developed - digestive, respiratory and circulatory system.
- not well-developed - retains fetal excretory system with a fully functional mesonephric kidney and undifferentiated gonads and genitalia.
Oocyte
Ovarian Follicle Development
The following data is from a histological study of ovaries from adult female koalas.[8]
- primordial follicles - have a small primary oocyte surrounded by a few squamous epithelial cells
- primary follicles - have a single layer of cuboidal granulosa cells around the oocyte.
- secondary follicles - have two or more layers of granulosa cells but no antrum
- tertiary follicles (Graafian) - have many layers of granulosa cells surrounding a follicular fluid-filled antrum of variable size.
- oocytes about 140 µm in diameter (range 110–162 µm: n = 5 individuals) surrounded by a zona pellucida (ZP) about 8 µm thick, which is twice as thick as most other marsupial species.
Marsupial eggs are enclosed by a series of layers:[9]
- zona pellucida, three zona proteins (ZPA, ZPB, ZPC)
- an additional extracellular matrix coat that lines the zona pellucida also occurs in some species.
- mucoid coat
- outer shell coat.
- Links: Oocyte Development
Spermatozoa
The spermatozoa head is hook-shaped with the most of the acrosomal contents lying within a nuclear concavity. Spermatozoa nuclei show a range of morphologies and a tendency to swell after cryopreservation procedures.[10]
- Links: Spermatozoa Development
References
- ↑ Morris KM, O'Meally D, Zaw T, Song X, Gillett A, Molloy MP, Polkinghorne A & Belov K. (2016). Characterisation of the immune compounds in koala milk using a combined transcriptomic and proteomic approach. Sci Rep , 6, 35011. PMID: 27713568 DOI.
- ↑ <pubmed>21098569</pubmed>
- ↑ <pubmed>20591325</pubmed>
- ↑ <pubmed>18950846</pubmed>
- ↑ <pubmed>9543340</pubmed>
- ↑ <pubmed>11943495</pubmed>
- ↑ <pubmed>11999321</pubmed>
- ↑ <pubmed>16928207</pubmed>
- ↑ <pubmed>10729728</pubmed>
- ↑ <pubmed>17609294</pubmed>
Reviews
<pubmed></pubmed> <pubmed>25091911</pubmed> <pubmed>8371091</pubmed>
Articles
<pubmed>16928207</pubmed> <pubmed>11943495</pubmed> <pubmed>11303907</pubmed>
Books
Search PubMed
Note searches using the term "Koala" will also find papers that refer to the KOALA Birth Cohort Study, a European study not related to the Australian animal.
Search PubMed: Phascolarctos cinereus | Koala development | marsupial development
External Links
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Cite this page: Hill, M.A. (2024, May 21) Embryology Koala Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Koala_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G