scholarly journals The RAG transposon is active through the deuterostome evolution and domesticated in jawed vertebrates

2017 ◽  
Vol 69 (6) ◽  
pp. 391-400 ◽  
Author(s):  
Jose Ricardo Morales Poole ◽  
Sheng Feng Huang ◽  
Anlong Xu ◽  
Justine Bayet ◽  
Pierre Pontarotti
Keyword(s):  
Deuterostome Evolution

scholarly journals Sea urchin larvae utilize light for regulating the pyloric opening

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Junko Yaguchi ◽  
Shunsuke Yaguchi
Keyword(s):  
Signaling Pathway ◽  
Digestive Tract ◽  
Sea Urchin ◽  
Visual Information ◽  
Biological Activities ◽  
Regulatory System ◽  
Sister Group ◽  
Animal Evolution ◽  
Deuterostome Evolution ◽  
Visual Systems

Abstract Background Light is essential for various biological activities. In particular, visual information through eyes or eyespots is very important for most of animals, and thus, the functions and developmental mechanisms of visual systems have been well studied to date. In addition, light-dependent non-visual systems expressing photoreceptor Opsins have been used to study the effects of light on diverse animal behaviors. However, it remains unclear how light-dependent systems were acquired and diversified during deuterostome evolution due to an almost complete lack of knowledge on the light-response signaling pathway in Ambulacraria, one of the major groups of deuterostomes and a sister group of chordates. Results Here, we show that sea urchin larvae utilize light for digestive tract activity. We found that photoirradiation of larvae induces pyloric opening even without addition of food stimuli. Micro-surgical and knockdown experiments revealed that this stimulating light is received and mediated by Go(/RGR)-Opsin (Opsin3.2 in sea urchin genomes) cells around the anterior neuroectoderm. Furthermore, we found that the anterior neuroectodermal serotoninergic neurons near Go-Opsin-expressing cells are essential for mediating light stimuli-induced nitric oxide (NO) release at the pylorus. Our results demonstrate that the light>Go-Opsin>serotonin>NO pathway functions in pyloric opening during larval stages. Conclusions The results shown here will lead us to understand how light-dependent systems of pyloric opening functioning via neurotransmitters were acquired and established during animal evolution. Based on the similarity of nervous system patterns and the gut proportions among Ambulacraria, we suggest the light>pyloric opening pathway may be conserved in the clade, although the light signaling pathway has so far not been reported in other members of the group. In light of brain-gut interactions previously found in vertebrates, we speculate that one primitive function of anterior neuroectodermal neurons (brain neurons) may have been to regulate the function of the digestive tract in the common ancestor of deuterostomes. Given that food consumption and nutrient absorption are essential for animals, the acquirement and development of brain-based sophisticated gut regulatory system might have been important for deuterostome evolution.

Deuterostome evolution: early development in the enteropneust hemichordate, Ptychodera flava

2001 ◽  
Vol 3 (6) ◽  
pp. 375-390 ◽  
Author(s):  
Jonathan Q. Henry ◽  
Kunifumi Tagawa ◽  
Mark Q. Martindale
Keyword(s):  
Early Development ◽  
Deuterostome Evolution ◽  
Ptychodera Flava

scholarly journals Cambrian Chordates and Vetulicolians

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 354 ◽  
Author(s):  
McMenamin
Keyword(s):  
Retinoic Acid ◽  
Fossil Record ◽  
Posterior Region ◽  
Early Cambrian ◽  
Anterior Section ◽  
Deuterostome Evolution ◽  
Sudden Appearance ◽  
The Subject ◽  
Range Of Variation

Deuterostomes make a sudden appearance in the fossil record during the early Cambrian. Two bilaterian groups, the chordates and the vetulicolians, are of particular interest for understanding early deuterostome evolution, and the main objective of this review is to examine the Cambrian diversity of these two deuterostome groups. The subject is of particular interest because of the link to vertebrates, and because of the enigmatic nature of vetulicolians. Lagerstätten in China and elsewhere have dramatically improved our understanding of the range of variation in these ancient animals. Cephalochordate and vertebrate body plans are well established at least by Cambrian Series 2. Taken together, roughly a dozen chordate genera and fifteen vetulicolian genera document part of the explosive radiation of deuterostomes at the base of the Cambrian. The advent of deuterostomes near the Cambrian boundary involved both a reversal of gut polarity and potentially a two-sided retinoic acid gradient, with a gradient discontinuity at the midpoint of the organism that is reflected in the sharp division of vetulicolians into anterior and posterior sections. A new vetulicolian (Shenzianyuloma yunnanense nov. gen. nov. sp.) with a laterally flattened, polygonal anterior section provides significant new data regarding vetulicolians. Its unsegmented posterior region (‘tail’) bears a notochord and a gut trace with diverticula, both surrounded by myotome cones.

scholarly journals Conodonts, Calcichordates and the Origin of Vertebrates

Fossil Record ◽  
1998 ◽  
Vol 1 (1) ◽  
pp. 81-91 ◽  
Author(s):  
J. Bergström ◽  
W. W. Naumann ◽  
J. Viehweg ◽  
M. Martí-Mus
Keyword(s):  
Soft Part ◽  
Body Plan ◽  
Burgess Shale ◽  
Life Orientation ◽  
Deuterostome Evolution ◽  
Body Design

Interpretation of early deuterostome evolution and relationships has been hampered by the lack of soft-part preservation in most groups. In addition, a recently revealed upside-down life orientation of vertebrates (the only real notoneuralians) compared to other bilateral animals has been misinterpreted as evidence for a unique body design in all deuterostomes, misleading any search for relatives. Regarding echinoderms, the variety of body plans is confusing. The interpretation of some fossils with echinoderm-type calcite skeletons as “calcichordate” ancestors of chordates, however, involves a hypothetical reconstruction of an unusual body plan and a long series of hypothetical transitions. The number of necessary steps is much lower if cephalochordates (amphioxus or lancelet) are derived directly from hemichordate enteropneusts. “Sensation interpretations” of fossils (Yunnanozoon, Cathaymyrus) from Burgess Shale type deposits have added further confusion. Soft-part preservation of conodont animals, with V-shaped myomeres and a notochord, shows that they were segmented chordates, while probable eyes and teeth suggest that they were already on the vertebrate side. <br><br> Die Interpretation früher Deuterostomia hinsichtlich ihrer Evolution und verwandtschaftlichen Beziehungen ist in den meisten Gruppen durch den Mangel an Weichkörpererhaltung sehr erschwert. Die kürzlich entdeckte Tatsache, daß Vertebraten, d. h. die einzigen echten Notoneuralia, im Gegensatz zu anderen bilateral symmetrischen Organismen eine mit ihrer ursprünglichen Oberseite nach unten gerichtete Lebensstellung einnehmen, hat zu der irrtümlichen Ansicht geführt, daß alle Deuostomia über einen im Tierreich einzigartigen Bauplan verfügen. Diese Interpretation brachte naturgemäß jede Suche nach Verwandtschaftsverhältnissen auf Abwege. <br><br> Hinsichtlich der Echinodermata ist die bauplanmäßige Variation in der Tat verwirrend. Die Interpretation einiger Fossilien mit Echinodermen-ähnlichen Kalzitskeletten als “calcichordate” Vorfahren der Chordata setzt jedoch die hypothetische Rekonstruktion eines ungewöhnlichen Bauplans sowie eine lange Serie hypothetischer Übergänge voraus. Die Anzahl der notwendigen Schritte ist sehr viel geringer. wenn Cephalochordaten (Amphioxus oder das Lanzettfischchen) von hemichordaten Enteropneusta abgeleitet werden. Zusätzliche Verwirrung hat es durch sensationelle Interpretationen von Fossilien, Wie Yunnanozoon und Cathaymyrus aus Burgess-Schiefer-artigen Ablagerungen gegeben. Weichkörpererhaltung von Conodontentieren, die V-förmige Myomere sowie einen Notochord besitzen, zeigen, daß es sich um segmentierte Chordata handelte, während sie die Präsenz möglicher Augenstrukturen und Zähne bereits auf die Seite der Vertebraten stellt. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.19980010106" target="_blank">10.1002/mmng.19980010106</a>

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