Showing papers by "Daniel Graf published in 2019"
01 Jan 2019
TL;DR: It is reported that sleep-disordered breathing (including its severe form, obstructive sleep apnea) in children is associated with reduced mandibular cortical width, and this association might be a direct consequence of reduced bone health to sleep- disordered breathing or a reflection that reduced bone formation underlies the development of sleep- Disordered breathing.
Abstract: Introduction:Evidence from the adult population suggests that sleep-disordered breathing (SDB) (i.e., obstructive sleep apnea [OSA]) is negatively associated with bone mineral density. Whether a si...
8 citations
TL;DR: The adult nkx3.2 null zebrafish phenotype is interpreted not as a reversal to an ancestral state, but as convergence due to similar functional requirement of feeding without mobile jaws, which implies that functionally viable morphological patterns are finite, with or without functional jaws.
Abstract: The vertebrate jaw is a versatile feeding apparatus that facilitated explosive diversification. To function, it requires a joint between the upper and lower jaws, so jaw joint defects - such as osteoarthritis or even ankylosis - are often highly disruptive and difficult to study. To describe consequences of jaw-joint dysfunction, we engineered two independent null alleles of a single jaw-joint marker gene, nkx3.2, in zebrafish. These mutations caused zebrafish to become functionally jawless via fusion of the upper and lower jaw cartilages (ankylosis). Despite lacking jaw joints, nkx3.2 mutants survive to adulthood and accommodate this defect by: a) remodeling their skulls; and b) altering their behavior from suction feeding to ram feeding. As a result of remodeling, nkx3.2 mutants developed superficial similarities to the skull shapes observed in two lineages of ancient jawless vertebrates (anaspids and furcacaudiid thelodonts), including: a fixed open gape, reduced snout, and enlarged branchial region. However, no homology exists in individual skull elements between these taxa, and most of the modified elements in the mutant zebrafish occur outside known expression domains of nkx3.2. Therefore, we interpret the adult nkx3.2 phenotype not as a reversal to an ancestral state, but as convergence due to similar functional requirement of feeding without moveable jaws. This remarkable convergence strongly suggests that jaw movements themselves dramatically influence the development of jawed vertebrate skulls, which implies that functionally viable skull morphologies are finite, with or without functional jaws. Because nkx3.2 null zebrafish display prominent joint ankylosis, drastically modified skull shape, and altered feeding behaviors, these mutants provide a unique model with which to investigate mechanisms of skeletal remodeling and joint diseases.
3 citations
TL;DR: In this paper, two independent null alleles of a single jaw-joint marker gene, nkx3.2, in zebrafish were found to become functionally jawless via a fusion between the upper and lower jaw cartilages (ankylosis).
Abstract: The vertebrate jaw is a versatile feeding apparatus that facilitated explosive diversification. Its functions require a joint between the upper and lower jaws, so jaw joint defects — such as osteoarthritis or even ankylosis — are often highly disruptive and difficult to study. To describe consequences of jaw joint dysfunction, we engineered two independent null alleles of a single jaw-joint marker gene, nkx3.2, in zebrafish. The mutations caused the fish to become functionally jawless via a fusion between the upper and lower jaw cartilages (ankylosis). Surviving to adulthood despite lacking jaw joints, nkx3.2 mutants accommodate this defect by: a) remodeling their skulls drastically from juvenile to adult stages; and b) altering their feeding behaviors from suction to ram feeding. As a result of the remodeling, nkx3.2 mutants developed superficial similarities to the skull shapes observed in two lineages of ancient jawless vertebrates (anaspids and furcacaudiform thelodonts), including: a fixed open gape, reduced snout, and enlarged branchial region. However, no homology exists in individual skull elements between these taxa, and most of the modified elements in the mutant zebrafish occur outside known expression domains of nkx3.2. Therefore, we interpret the adult nkx3.2 phenotype not as a reversal to an ancestral state, but as convergence due to similar functional requirement of feeding without mobile jaws. This remarkable convergence underscores jaw joint functions as a powerful constraint during the development of jawed vertebrate skulls, which implies that functionally viable morphological patterns are finite, with or without functional jaws. Because nkx3.2 null zebrafish display prominent joint ankylosis, drastically modified skull shape, and altered feeding behaviors, these mutants provide a unique model with which to investigate mechanisms of skeletal remodeling and joint diseases.