Developmental and functional controls on enrolment in an ancient, extinct arthropod
Developmental and functional controls on enrolment in an ancient, extinct arthropod
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DOI：
10.1098/rspb.2023.0871
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发表时间：
2023-06-14
影响因子：
4.7
通讯作者：
Hughes, Nigel C. C.
中科院分区：
文献类型：
--
作者：
Esteve, Jorge;Hughes, Nigel C. C.
三维模型揭示了模型生物（4.29 亿年前的三叶虫 Aulacopleura koninckii）发育过程中外骨骼参与机制如何变化，以深入了解古代节肢动物的发育。躯干内节段的数量、大小和分配的变化，加上在入组期间需要保持软组织的有效外骨骼屏蔽，使得有必要在成熟生长开始时改变入组方式。在早期的生长阶段，登记呈球形，躯干的腹面与头部的腹面完全吻合。在以后的生长中，如果要保持侧向外骨骼封装，躯干长度比例不允许这种精确的配合，需要替代的非球形登记样式。我们的研究倾向于在以后的生长过程中采取后躯干延伸到头部前部之外的姿势。这种登记的变化适应了成熟树干节数的显着变化模式，众所周知，这是该物种发育的特征。它表明，早期节段发育受到非常精确控制的动物如何能够意识到成熟节段数量的显着变化，这显然与身体挑战、低氧环境中的生活有关。
Three-dimensional models reveal how the mechanics of exoskeletal enrolment changed during the development of a model organism for insights into ancient arthropod development, the 429-million-year-old trilobite Aulacopleura koninckii. Changes in the number, size and allocation of segments within the trunk, coupled with the need to maintain effective exoskeletal shielding of soft tissue during enrolment, necessitated a transition in enrolment style about the onset of mature growth. During an earlier growth phase, enrolment was sphaeroidal, with the venter of the trunk fitting exactly against that of the head. In later growth, if lateral exoskeletal encapsulation was to be maintained trunk length proportions did not permit such exact fitting, requiring an alternative, non-sphaeoridal enrolment style. Our study favours the adoption of a posture in later growth in which the posterior trunk extended beyond the front of the head. This change in enrolment accommodated a pattern of notable variation in the number of mature trunk segments, well known to characterize the development of this species. It suggests how an animal whose early segmental development was remarkably precisely controlled was able to realize the marked variation in mature segment number that was related, apparently, to life in a physically challenging, reduced oxygen setting.