Crawling movement in eukaryotic cells requires coordination of leading-edge protrusion with cell body retraction [1-3]. Protrusion is driven by actin polymerization along the leading edge [4]. The mechanism of retraction is less clear; myosin contractility may be involved in some cells [5] but is not essential in others [6-9]. In Ascaris sperm, protrusion and retraction are powered by the major...

Src tyrosine kinases have been implicated in axonal growth and guidance; however, the underlying cellular mechanisms are not well understood. Specifically, it is unclear which aspects of actin organization and dynamics are regulated by Src in neuronal growth cones. Here, we investigated the function of Src2 and one of its substrates, cortactin, in lamellipodia and filopodia of Aplysia growth co...

Introduction: Patients with dental Class II bialveolar protrusion are generally treated by extracting the four first premolars or two first and two second premolars, and retracting the anterior teeth. This case report describes the treatment of an adult patient with bialveolar protrusion, a Class II canine and molar relationship, and lip protrusion. Methods: In this patient, the maxillary right...

The aims of this study were to investigate how the Peer Assessment Rating (PAR index) predicts the perceived need for orthodontic treatment of mandibular protrusion in Japanese subjects, and to elucidate whether the perceived need for treatment was affected by the raters' orthodontic expertise. The subjects were 110 dental students and 32 orthodontists. We showed them casts of 10 untreated mand...

Cells propel themselves along a substrate by organizing structures at the leading edge called lamellipodia that contain the actin network, myosin, integrin, and other proteins. In this article, we describe a quantitative model that couples the response of stretch-sensitive proteins in the lamellipodia to the dynamics of the actin cytoskeleton, therefore allowing the cell to respond to different...

Cells polarize to a single front and rear to achieve rapid actin-based motility, but the mechanisms preventing the formation of multiple fronts are unclear. We developed embryonic zebrafish keratocytes as a model system for investigating establishment of a single axis. We observed that, although keratocytes from 2 d postfertilization (dpf) embryos resembled canonical fan-shaped keratocytes, ker...

Cell migration involves many steps, including membrane protrusion and the development of new adhesions. Here we have investigated whether there is a link between actin polymerization and integrin engagement. In response to signals that trigger membrane protrusion, the actin-related protein (Arp)2/3 complex transiently binds to vinculin, an integrin-associated protein. The interaction is regulat...

We have pioneered an in vitro pseudopod-generation model wherein suspended tumor cells are stimulated to form pseudopods into glass micropipettes in response to soluble collagen type IV (CIV). Pertussis toxin and removing intracellular calcium were found previously to be inhibitory to that process. We now extend those observations to dissect the roles of transmembrane calcium influx and circula...

Using data automatically acquired by microinterferometry from large numbers of chick fibroblasts, we have detected rapid microfluctuations in the rates of protrusion and retraction of the cell margin which were strongly suppressed by colcemid, nocodazole and taxol. Fluctuations in the rate of retraction of the margin were about twice as powerful as fluctuations in the rate of protrusion. High-f...

Tongue-hold swallow (THS) is a therapeutic maneuver used to increase the posterior pharyngeal wall motion during swallowing. This maneuver has also been reported to result in increased activation of the suprahyoid muscles. The hypothesis of this study was that the degree of suprahyoid muscle activation would depend on the tongue protrusion-length. The aim of this study was to investigate the ac...