Retention of fish-like odontode overgrowth in Permian tetrapod dentition supports outside-in theory of tooth origins

Teeth are often thought of as structures that line the margins of the mouth; however, tooth-like structures called odontodes are commonly found on the dermal bones of many Palaeozoic vertebrates including early jawless fishes. ‘Odontode’ is a generalized term for all tooth-like dentine structures that have homologous tissues and development. This definition includes true teeth and the odontodes of early ‘fishes’, which have been recently examined to gain new insights into the still unresolved origin of teeth. Two leading hypotheses are frequently referenced in this debate: the ‘outside-in’ hypothesis, which posits that dermal odontodes evolutionarily migrate into the oral cavity, and the ‘inside-out’ hypothesis, which posits that teeth originated in the oropharyngeal cavity and then moved outwards into the oral cavity. Here, we show that, unlike the well-known one-to-one replacement patterns of marginal dentition, the palatal dentition of the early Permian tetrapods, including the dissorophoid amphibian Cacops and the early reptile Captorhinus , is overgrown by a new layer of bone to which the newest teeth are then attached. This same overgrowth pattern has been well documented in dermal and oral odontodes (i.e. teeth) of early fishes . We propose that this pattern represents the primitive condition for vertebrates and may even predate the origin of jaws. Therefore, this pattern crosses the fish–tetrapod transition, and the retention of this ancestral pattern in the palatal dentition of early terrestrial tetrapods provides strong support for the ‘outside-in’ hypothesis of tooth origins.

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The clavobranchialis musculature in sarcopterygian fishes, and contribution to osteichthyan feeding and respiration

Contributions to Zoology ◽

10.1163/18759866-07201002 ◽

2003 ◽

Vol 72 (1) ◽

pp. 17-37 ◽

Cited By ~ 5

Author(s):

Zerina Johanson

Keyword(s):

Oral Cavity ◽

Negative Pressure ◽

Ventral Surface ◽

Pectoral Girdle ◽

Gill Chamber ◽

Bony Fishes ◽

Oropharyngeal Cavity ◽

Actinopterygian Fishes ◽

Negative Pressures

Various fossil lungfish taxa preserve distinct depressions on the smooth postbranchial lamina of the dermal pectoral girdle. These depressions are largely unknown in other sarcopterygian fishes, but are present in the rhizodont sarcopterygian Strepsodus. Comparisons with extant actinopterygian fishes suggest these depressions mark the point of origin for the clavobranchialis musculature, extending anterodorsally into the gill chamber to insert on the ventral surface of the ceratobranchial(s). Studios examining feeding and respiratory mechanisms of bony fishes (Osteichthyes) have emphasised the role of mandibular depression in generating negative pressures within the oral cavity to draw in water/air/food via suction. However, phylogenetically basal actinopterygians, fossil lungfish and other fossil sarcopterygians (such as Strepsodus) lack the apomorphies that increase suction among bony fishes. In these taxa the clavobranchialis muscles may serve to augment this negative pressure by retracting the ceratobranchials and increasing the size of the oral/ oropharyngeal cavity. A comparable action is performed by the chondrichthyan coracobranchiales muscles, particularly during feeding, and the function of these ventral gill arch muscles is likely to be a synapomorphy of jawed vertebrates (Gnathostomata). This musculature is absent from jawless vertebrates such as the Osteostraci.

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Progressive Oxidation of Selected Particles of Carbon Black: Further Evidence for a New Microstructural Model

Rubber Chemistry and Technology ◽

10.5254/1.3544829 ◽

1966 ◽

Vol 39 (1) ◽

pp. 1-13 ◽

Cited By ~ 73

Author(s):

F. A. Heckman ◽

D. F. Harling

Keyword(s):

Particle Size ◽

Carbon Black ◽

Electron Micrographs ◽

Strong Support ◽

Electron Micrography ◽

Microstructural Model ◽

A New Technique ◽

Inside Out ◽

Individual Particles ◽

Oxidative Attack

Abstract A new technique is described for following the effects of successive increments of oxidative attack upon the same particles of carbon black. Oxidation was carried out under controlled conditions outside of the microscope, followed by electron micrography of selected grid areas. Electron micrographs show that normal thermal and furnace blacks generally oxidize from the inside out, forming capsules of unchanged external dimensions. Differences in rate of oxidation of individual particles are observed with thermal blacks; these rates are, however, independent of particle size. In agreement with earlier evidence, graphitized thermal blacks oxidize from the outside in. Strong support is given for a new “concentric crystallite” model of carbon black microstructure. On the basis of this model, slippage of rubber molecules on the surface of carbon black can be readily understood.

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Observational evidence for an inside-out substorm onset scenario

Annales Geophysicae ◽

10.5194/angeo-27-2129-2009 ◽

2009 ◽

Vol 27 (5) ◽

pp. 2129-2140 ◽

Cited By ~ 64

Author(s):

M. G. Henderson

Keyword(s):

Neutral Line ◽

Strong Support ◽

Linear Increase ◽

Substorm Onset ◽

Linear Growth Rate ◽

Two Phase ◽

Particle Injection ◽

Expansion Phase ◽

The North ◽

Inside Out

Abstract. We present observations which provide strong support for a substorm expansion phase onset scenario in which a localized inner magnetospheric instability developed first and was later followed by the development of a Near Earth Neutral Line (NENL) farther down-tail. Specifically, we find that the onset began as a localized brightening of an intensified growth phase arc which developed as a periodic series of arc-aligned (i.e. azimuthally arrayed) bright spots. As the disturbance grew, it evolved into vortical structures that propagated poleward and eventually morphed into an east-west aligned arc system at the poleward edge of the auroral substorm bulge. The evolution of the auroral intensity is consistent with an exponential growth with an e-folding time of around 188 s (corresponding to a linear growth rate, γ of 5.33×10−3 s−1). During the initial breakup, no obvious distortions of auroral forms to the north were observed. However, during the expansion phase, intensifications of the poleward boundary of the expanding bulge were observed together with the equatorward ejection of auroral streamers into the bulge. A strong particle injection was observed at geosynchronous orbit, but was delayed by several minutes relative to onset. Ground magnetometer data also shows a two phase development of mid-latitude positive H-bays, with a quasi-linear increase in H between the onset and the injection. We conclude that this event provides strong evidence in favor of the so-called "inside-out" substorm onset scenario in which the near Earth region activates first followed at a later time by the formation of a near-to-mid tail substorm X-line. The ballooning instability is discussed as a likely mechanism for the initial onset.

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Amyloid β-peptide and Alzheimer's disease

Essays in Biochemistry ◽

10.1042/bse0560099 ◽

2014 ◽

Vol 56 ◽

pp. 99-110 ◽

Cited By ~ 15

Author(s):

David Allsop ◽

Jennifer Mayes

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Senile Plaques ◽

Strong Support ◽

Amyloid Β ◽

Amyloid Β Peptide ◽

Amyloid Cascade Hypothesis ◽

Sequence Of Events ◽

Aβ Amyloid ◽

Amyloid Cascade

One of the hallmarks of AD (Alzheimer's disease) is the formation of senile plaques in the brain, which contain fibrils composed of Aβ (amyloid β-peptide). According to the ‘amyloid cascade’ hypothesis, the aggregation of Aβ initiates a sequence of events leading to the formation of neurofibrillary tangles, neurodegeneration, and on to the main symptom of dementia. However, emphasis has now shifted away from fibrillar forms of Aβ and towards smaller and more soluble ‘oligomers’ as the main culprit in AD. The present chapter commences with a brief introduction to the disease and its current treatment, and then focuses on the formation of Aβ from the APP (amyloid precursor protein), the genetics of early-onset AD, which has provided strong support for the amyloid cascade hypothesis, and then on the development of new drugs aimed at reducing the load of cerebral Aβ, which is still the main hope for providing a more effective treatment for AD in the future.

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A Support Program

Language Speech and Hearing Services in Schools ◽

10.1044/0161-1461.2502.112 ◽

1994 ◽

Vol 25 (2) ◽

pp. 112-114 ◽

Cited By ~ 3

Author(s):

Henna Grunblatt ◽

Lisa Daar

Keyword(s):

Hearing Aids ◽

School Counselor ◽

Support Program ◽

Educational Audiology ◽

Part Program ◽

One To One

A program for providing information to children who are deaf about their deafness and addressing common concerns about deafness is detailed. Developed by a school audiologist and the school counselor, this two-part program is geared for children from 3 years to 15 years of age. The first part is an educational audiology program consisting of varied informational classes conducted by the audiologist. Five topics are addressed in this part of the program, including basic audiology, hearing aids, FM systems, audiograms, and student concerns. The second part of the program consists of individualized counseling. This involves both one-to-one counseling sessions between a student and the school counselor, as well as conjoint sessions conducted—with the student’s permission—by both the audiologist and the school counselor.

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Oral and Oropharyngeal Sensory Function in Adults With Chronic Obstructive Pulmonary Disease

American Journal of Speech-Language Pathology ◽

10.1044/2019_ajslp-19-00095 ◽

2020 ◽

Vol 29 (2) ◽

pp. 864-872

Author(s):

Fernanda Borowsky da Rosa ◽

Adriane Schmidt Pasqualoto ◽

Catriona M. Steele ◽

Renata Mancopes

Keyword(s):

Chronic Obstructive Pulmonary Disease ◽

Oral Cavity ◽

Pulmonary Disease ◽

Thermal Sensation ◽

Sensory Function ◽

Control Group ◽

Chronic Obstructive ◽

Obstructive Pulmonary Disease ◽

Age Related ◽

Copd Patients

Introduction The oral cavity and pharynx have a rich sensory system composed of specialized receptors. The integrity of oropharyngeal sensation is thought to be fundamental for safe and efficient swallowing. Chronic obstructive pulmonary disease (COPD) patients are at risk for oropharyngeal sensory impairment due to frequent use of inhaled medications and comorbidities including gastroesophageal reflux disease. Objective This study aimed to describe and compare oral and oropharyngeal sensory function measured using noninstrumental clinical methods in adults with COPD and healthy controls. Method Participants included 27 adults (18 men, nine women) with a diagnosis of COPD and a mean age of 66.56 years ( SD = 8.68). The control group comprised 11 healthy adults (five men, six women) with a mean age of 60.09 years ( SD = 11.57). Spirometry measures confirmed reduced functional expiratory volumes (% predicted) in the COPD patients compared to the control participants. All participants completed a case history interview and underwent clinical evaluation of oral and oropharyngeal sensation by a speech-language pathologist. The sensory evaluation explored the detection of tactile and temperature stimuli delivered by cotton swab to six locations in the oral cavity and two in the oropharynx as well as identification of the taste of stimuli administered in 5-ml boluses to the mouth. Analyses explored the frequencies of accurate responses regarding stimulus location, temperature and taste between groups, and between age groups (“≤ 65 years” and “> 65 years”) within the COPD cohort. Results We found significantly higher frequencies of reported use of inhaled medications ( p < .001) and xerostomia ( p = .003) in the COPD cohort. Oral cavity thermal sensation ( p = .009) was reduced in the COPD participants, and a significant age-related decline in gustatory sensation was found in the COPD group ( p = .018). Conclusion This study found that most of the measures of oral and oropharyngeal sensation remained intact in the COPD group. Oral thermal sensation was impaired in individuals with COPD, and reduced gustatory sensation was observed in the older COPD participants. Possible links between these results and the use of inhaled medication by individuals with COPD are discussed.

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