Year-end Sale % OFF 
Abstract
Oscillatory and sequential processes have been implicated in the spatial patterning of many embryonic tissues. For example, molecular clocks delimit segmental boundaries in vertebrates and insects and mediate lateral root formation in plants, whereas sequential gene activities are involved in the specification of regional identities of insect neuroblasts, vertebrate neural tube, vertebrate limb, and insect and vertebrate body axes. These processes take place in various tissues and organisms, and, hence, raise the question of what common themes and strategies they share. In this article, we review 2 processes that rely on the spatial regulation of periodic and sequential gene activities: segmentation and regionalization of the anterior–posterior (AP) axis of animal body plans. We study these processes in species that belong to 2 different phyla: vertebrates and insects. By contrasting 2 different processes (segmentation and regionalization) in species that belong to 2 distantly related phyla (arthropods and vertebrates), we elucidate the deep logic of patterning by oscillatory and sequential gene activities. Furthermore, in some of these organisms (e.g., the fruit fly Drosophila), a mode of AP patterning has evolved that seems not to overtly rely on oscillations or sequential gene activities, providing an opportunity to study the evolution of pattern formation mechanisms.
Highlights
Segmentation, known as metamerism, refers to the organization of the body into repeating units of similar structure along the anterior–posterior (AP) axis
Segmentation is usually coupled with regionalization, a process in which the animal body plan is divided into several fates, such that different segments along the AP axis of segmented organisms acquire different identities and develop distinct morphological features
Translating a temporal sequence into a spatial pattern seems to be a common strategy in development, as it has been discovered in other developmental processes such as lateral root formation in plants [15,16] and fate specification in insect neuroblasts [17,18,19,20], the vertebrate neural tube [21,22,23], and the vertebrate limb bud [24,25,26,27]
Summary
Segmentation, known as metamerism, refers to the organization of the body into repeating units of similar structure along the anterior–posterior (AP) axis. Segmentation of the AP axis in vertebrates and short-germ insects is achieved rhythmically and sequentially through the oscillatory activity of a set of genes whose expression transverses the AP axis from posterior to anterior, generating wave-like patterns (Figs 1C and 2A).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
