Left–right asymmetry of the gnathostome skull: Its evolutionary, developmental, and functional aspects

Abstract

Summary: Much of the gnathostome (jawed vertebrate) evolutionary radiation was dependent on the ability to sense and interpret the environment and subsequently act upon this information through utilization of a specialized mode of feeding involving the jaws. While the gnathostome skull, reflective of the vertebrate ba€ uplan, typically is bilaterally symmetric with right (dextral) and left (sinistral) halves essentially representing mirror images along the midline, both adaptive and abnormal asymmetries have appeared. Herein we provide a basic primer on studies of the asymmetric development of the gnathostome skull, touching briefly on asymmetry as a field of study, then describing the nature of cranial development and finally underscoring evolutionary and functional aspects of left-right asymmetric cephalic development. genesis 52:515-527, 2014. V C 2014 Wiley Periodicals, Inc.

Methodology for Morphometric Analysis of Modern Human Contralateral Premolars

“…The connection between dental FA and overall health is contested, as other studies have not found any biological meaningful correlation with morbidity [20]. Asymmetry is not only manifested in structures either belonging to the object or matching type of symmetry but may also present itself in the midsagittal plan such as a spina nasalis anterior deviation or an asymmetric sagittal skull suture resulting in bulging away from the midline [21].…”

A comprehensive overview of the developmental basis and adaptive significance of a textbook polymorphism: head asymmetry in the cichlid fish Perissodus microlepis

“…Examples of this kind of polymorphism are seen in some occurrences of bilateral asymmetries (e.g., Palmer, 2009;Schilthuizen, 2013). Here, left and right individuals differ from a typically bilateral symmetric organism, a pattern that has repeatedly emerged in both vertebrates and invertebrates and is thought to be adaptive (Ludwig, 1932;Palmer, 2004Palmer, , 2009Compagnucci et al, 2014;Palmer, 2016, e.g., Lucky et al,. 2012Tobo et al, 2012;Matsui et al, 2013;Kurvers et al, 2017).…”

Primary Cilia as a Possible Link between Left-Right Asymmetry and Neurodevelopmental Diseases

“…The genes involved in vertebrate left-right asymmetry establishment may also participate in the lateralization of certain brain regions in Danio rerio [ 21 ] and dogfish [ 23 ], and eye migration to the side in flatfishes Paralichthys olivaceus and Verasper variegatus [ 47 ]. Asymmetric expression of Nodal-cascade proteins in the brain of developing flatfishes has been correlated with the neuronal architecture associated with the alteration of the position of the eyes and orbits [ 48 ]. Since cilia are involved in visceral left-right asymmetry in mammals and some other vertebrates, and disturbances in expression of the cilia genes can lead to abnormal left-right asymmetry (e.g., in primary ciliary dyskinesia), we aimed to test the idea that the functions of cilia do affect brain lateralization, and that disturbances of the ciliary structure and function would cause neurodevelopmental diseases.…”