Biology:Kakabekia
| Kakabekia Temporal range: Paleoproterozoic
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| Scientific classification | |
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| Genus: | Kakabekia E.S. Barghoorn & S.A. Tyler, 1965
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| Type species | |
| Kakabekia umbellata Barghoorn & Tyler, 1965
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| Species | |
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Kakabekia is a genus of microorganism. Kakabekia umbellata was first found in the 1.88 billion year old Gunflint Chert, and in 1966, a living member of the genus, Kakabekia barghoorniana was discovered in Wales - it is also found around the world, typically at 1000-2000m elevations. The roughly 2 billion year interval between these species has led some to call it the “oldest living fossil”.[1]
Anatomy
Kakabekia umbellata, as described by Barghoorn and Tyler in 1965 has an umbellate “mantle”, a stalk-like “stipe” and a “bulb” attached to it.[2] Morphology of K. barhoorniana differs; it has a round structure with radial segmentation.[3] They have a (possibly siliceous) ring around this structure.[4] Feulgen-positive material (DNA) was seen in “clots” in K. barghooriniana cytoplasms, placing them in the Prokaryotes.[citation needed]
Distribution
Kakabekia umbellata is known from the Gunflint chert of Canada . K. barghoorniana was first discovered in a soil sample cultured in ammonia from Harlech Castle, Wales in 1968.[5] Further research found K. b. in Iceland and Alaska, as well as other locations in Wales.
Metabolism
Kakabekia has an unusual metabolism. While it has no need for oxygen in its growth, it is not inhibited by it, like Clostridium. This, and the fact that it has some of the oxygen-utilising enzymes, suggest that it is a transition stage of oxygen-utilisation. Kakabekia barghoorni can only be grown in ammonia-rich conditions. This may reflect ancient atmosphere composition.
Ontogeny
Barghoorn and Tyler propose an ontogeny where, starting from a spore, the stipe is grown which then produced the umbellate "mantle".[2] In 1967, Licari and Cloud noted that many fossil "Huroniosporas" (a wastebasket taxon containing spore-like beings) have holes or "apertures" in them, suggesting a detachment point from Kakabekia stipes.[6] However, based on observations of living K. barghoorniana, Siegel et al. came to a very different conclusion. They found that the spore-like bodies would grow into a larger, spherical organism, encircled by the ring described above. Then, divisions form radiating from the center, and a stipe grows and releases a spore. After about 10 days, the organism degenerates and dies (senescence).[3]
References
- ↑ "Biology of the Precambrian Genus Kakabekia: New Observations on Living Kakabekia barghoorniana". Proceedings of the National Academy of Sciences of the United States of America 67 (2): 1005–10. October 1970. doi:10.1073/pnas.67.2.1005. PMID 16591868. Bibcode: 1970PNAS...67.1005S.
- ↑ 2.0 2.1 "Microorganisms from the Gunflint Chert: These structurally preserved Precambrian fossils from Ontario are the most ancient organisms known". Science 147 (3658): 563–75. February 1965. doi:10.1126/science.147.3658.563. PMID 17783259.
- ↑ 3.0 3.1 "Living relative of the microfossil Kakabekia". Science 156 (3779): 1231–4. June 1967. doi:10.1126/science.156.3779.1231. PMID 6025541. Bibcode: 1967Sci...156.1231S.
- ↑ Seckbach, Joseph (2013). Enigmatic Microorganisms and Life in Extreme Environments. Springer Science & Business Media. pp. 91–96. ISBN 978-9401148382.
- ↑ "A Living Organism Morphologically Comparable to the Precambrian Genus Kakabekia". American Journal of Botany 55 (6): 684–687. July 1968. doi:10.2307/2440525.
- ↑ "Reproductive structures and taxonomic affinities of some nannofossils from the gunflint iron formation". Proceedings of the National Academy of Sciences of the United States of America 59 (4): 1053–60. April 1968. doi:10.1073/pnas.59.4.1053. PMID 4870860. Bibcode: 1968PNAS...59.1053L.
External links
Wikidata ☰ Q16976713 entry
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