(1) These results provide the first demonstration that embryonic neurons supply agrin-like molecules to the synapses they form with embryonic muscle cells.
(2) The stimulation of the expression of agrin-related molecules in these long-term cultures requires the presence of chick embryo extract or fetal calf serum.
(3) Agrin, a protein isolated from the synapse-rich electric organ of Torpedo californica, induces the formation of specializations on myotubes in culture which resemble the post-synaptic apparatus at the vertebrate skeletal neuromuscular junction.
(4) Agrin enriched by immunoaffinity chromatography from the central nervous system induced large numbers of AChR aggregates on cultured myotubes.
(5) We conclude that agrin released by rat motor neurons induced the chick myotubes to aggregate AChRs.
(6) Agrin-induced formation of AChR aggregates was not prevented by inhibition of protein synthesis, consistent with our previous results that agrin-induced accumulation of AChRs occurs by lateral migration.
(7) The rat agrin protein is concentrated at synapses, where it may play a role in development and regeneration.
(8) Immunofluorescence shows that on myotubes incubated with agrin at 4 degrees C, agrin binds in a uniform, finely punctate pattern that correlates poorly with the distribution of AChRs.
(9) By contrast, actin (visualized with fluorescein-phalloidin) and tropomyosin did not show specific associations with agrin-induced AChR clusters.
(10) In the present study we examined the role of extracellular matrix components in agrin-induced differentiation.
(11) Myotubes stimulated with agrin at 37 degrees C for greater than or equal to 2 hr show a coclustering of agrin binding sites and AChRs.
(12) The accumulation of AChE and BuChE into agrin-induced aggregates occurred in the absence of any change in the amount, rate of synthesis, accumulation, and release, or molecular forms of either enzyme.
(13) We also characterized the expression of muscle-derived agrin-like molecules at clusters of AChR.
(14) Here I report that the major agrin-like proteins from the nervous system and other tissues of the chicken are immunochemically and biochemically similar.
(15) Thus, in developing muscle, agrin or a closely related molecule (a) is expressed before AchR clusters are detected; (b) is colocalized with the earliest AchR clusters formed; and (c) can be expressed in muscle and at sites of high AchR density independently of innervation.
(16) These results demonstrate that expression of a single gene encoding agrin confers receptor clustering that is restricted to specific sites of cell-muscle contact.
(17) Other lines of study have provided clues as to how nerve-derived (extracellular) AChR-cluster inducing factors such as agrin might activate 43k-driven postsynaptic membrane specialization.
(18) However, as dorsal and ventral premuscle masses condensed (stage 22-23), mesenchymal immunoreactivity for laminin and agrin-like proteins, but not the proteoglycan, became concentrated in these myogenic regions.
(19) Immunofluorescent staining with an anti-agrin antibody reactive at Rana but not at Xenopus neuromuscular junctions was positive only at cross-species nerve-muscle contacts involving Rana neurons.
(20) Here we present evidence that agrin is highly concentrated in the cell bodies of motor neurons and is transported to axon terminals which is consistent with the agrin hypothesis.
Grin
Definition:
(n.) A snare; a gin.
(v. i.) To show the teeth, as a dog; to snarl.
(v. i.) To set the teeth together and open the lips, or to open the mouth and withdraw the lips from the teeth, so as to show them, as in laughter, scorn, or pain.
(v. t.) To express by grinning.
(n.) The act of closing the teeth and showing them, or of withdrawing the lips and showing the teeth; a hard, forced, or sneering smile.
Example Sentences:
(1) "It is incredibly hard work," she says with a sly grin.
(2) There was nothing accidental about Saffiyah Khan’s easy nonchalance, grinning through the spitting rage of Ian Crossland at the EDL rally in Birmingham city centre at the weekend; Ieshia Evans knew there was more power in calm when she approached the police in Baton Rouge last summer.
(3) Then Obama himself swooped in with a big bear hug around Giffords's tiny frame, grinning widely before climbing to the rostrum for the speech.
(4) Thank you for your encouragement and good wishes,” Ma Jing, the director general of CCTV America, told the president, flanked by a number of grinning American staff.
(5) Who can complain of physical fear, of the nightmare of a baby eating its way out of your abdomen, of the loss of professional autonomy, staring at a stranger's idiotic grin?
(6) I have a self-satisfied grin just thinking about these expressions.
(7) People take pictures of themselves wherever they go, from cathedrals to airports to funerals , always the same face grinning at the camera.
(8) The thing that had me cracking up all night long is, I go through 20 years of everybody screaming to pass the ball,” Bryant said with a grin.
(9) Putin could have been forgiven for allowing himself a wry grin, as another court comprehensively trashed Berezovsky's reputation.
(10) The new No8 allowed a slight grin to creep over his face, seemingly struggling to contain his excitement.
(11) She reminds me of the time David was ridiculed for being photographed grinning inanely with a banana.
(12) Asked about his repeated gestures, grins and smirks towards the victims, she said it brought back memories of seeing him at Srebrenica.
(13) The final seconds of the movie are the most memorable, in which Smokey assures Big Worm he’s going to rehab, before hanging up the phone and lighting a joint with a mischievous grin to the camera.
(14) After Second World War army service, his physique, graceful carriage and radiant grin took him from lift attendant to Broadway and instant movie stardom in The Killers (1946).
(15) "We couldn't believe our eyes," grinned Shamad, recalling the sight of Tunisia's ousted despot, Zine al-Abidine Ben Ali, fleeing a land he had ruled for 23 years.
(16) "I have no idea," Farage barked back with something between a grin and a scowl.
(17) During mimetic actions, such as wrinkling the forehead, closing the eyes, blinking, grinning and blowing out the cheeks, EMG from 16 disk electrodes were concurrently recorded from the frontalis, orbicularis oculi, and orbicularis oris muscles on both sides.
(18) We’ll definitely show that on the day.” There was a twinkle in his eye and a slight grin on his face but Bale, make no mistake, was deadly serious.
(19) For Cohn, a teddy boy at heart, neither came close to the glamour and speed fix of the rapidly receding “golden age” he wrote about with such dash: Elvis’s “great ducktail plume and lopsided grin”, Phil Spector’s “beautiful noise”, and James Brown, “the outlaw, the Stagger Lee of his time”.
(20) There are pictures of firefighters, policemen, soldiers and members of the public, some grinning and holding up placards celebrating Bin Laden's execution.