| 2. |
- Igawa, T, et al.
(författare)
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Evolutionary history of the extant amphioxus lineage with shallow-branching diversification
- 2017
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1, s. 1157-
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Tidskriftsartikel (refereegranskat)abstract
- Amphioxus or lancelets have been regarded as a key animal in understanding the origin of vertebrates. However, the evolutionary history within this lineage remains unexplored. As the amphioxus lineage has likely been separated from other chordates for a very long time and displays a marked left-right asymmetry, its evolutionary history is potentially helpful in better understanding chordate and vertebrate origins. We studied the phylogenetic relationships within the extant amphioxus lineage based on mitochondrial genomes incorporating new Asymmetron and Epigonichthys populations, and based on previously reported nuclear transcriptomes. The resulting tree patterns are consistent, showing the Asymmetron clade diverging first, followed by the Epigonichthys and Branchiostoma clades splitting. Divergence time estimates based on nuclear transcriptomes with vertebrate calibrations support a shallow diversification of the extant amphioxus lineage in the Tertiary. These estimates fit well with the closure of seaways between oceans by continental drift, ocean currents, and present geographical distributions, and suggest a long cryptic history from the origin of amphioxus to its most recent diversification. Deduced character polarities based on phylogenetic analyses suggest that the common ancestor of the extant amphioxus existed in a tiny epibenthic state with larva-like appearance of extant amphioxus, likely with ciliate epidermis.
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| 3. |
- Igawa, Y, et al.
(författare)
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Cystometric findings in mice lacking muscarinic M2 or M3 receptors
- 2004
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Ingår i: Journal of Urology. - : Ovid Technologies (Wolters Kluwer Health). - 1527-3792 .- 0022-5347. ; 172:6, Part 1 of 2, s. 2460-2464
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The physiological importance of muscarinic M-3 and M-2 receptors for bladder function was investigated in vivo using mice lacking M-3 or M-2 receptors and littermate WT controls. Materials and Methods: Unanesthetized mice of each sex underwent continuous cystometry before and after administration of atropine (1 mg/kg(-1)). Results: Male M-3 knockout (KO) mice had longer voiding intervals, and larger micturition volumes and bladder capacity than M-2 KO or WT males. There was no significant difference in any cystometric parameters between male M-2 KO and WT mice. In females M-3 KO and M-2 KO mice had longer voiding intervals and larger micturition volumes than WT animals. Atropine had marked inhibitory effects on voiding efficacy in WT and M-2 KO mice but it had no effect on any cystometric parameters in M-3 KO mice. Conclusions: The current results confirm that M-3 receptor is the principal muscarinic receptor subtype responsible for bladder contraction and the role of M-2 receptors is of minor importance. Functional impairments found in M-3 KO mice were milder than those elicited by acute blockade of muscarinic receptors by atropine in WT mice, suggesting that noncholinergic mechanisms can compensate for a chronic loss of M-3 receptors.
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