Axoneme-MTs moving on Kinesin-1 bound to a coverslip
Axoneme-MT complexes were assembled with the axoneme fragment (denser region) at the minus end of the complex and the microtubule at the plus ends. The axoneme-MT complexes attach to purified bovine brain Kinesin-1 bound to a glass coverslip and move with the axoneme (minus) ends leading. Because Kinesin-1 is immobilized on the glass surface and the axoneme-MTs are moving on the immobilized motor, movement of the complexes with the axoneme leading shows that Kinesin-1 moves on microtubules towards the plus ends. The sequence shows two axoneme-MTs, both moving with the axoneme leading, and a single microtubule without an axoneme. The sequence has been speeded up by 12.5X real time. For further information regarding Kinesin-1 motility, go to the motility page.
Contributed by Sharyn Endow & Hebok Song
MT translocation and rotation driven by Ncd bound to a coverslip
MTs were grown from the plus ends of axoneme doublet seeds (denser regions), then stabilized by taxol. VE-DIC microscopy was used to record the motility of these doublet-MT complexes bound to Ncd on a coverslip as described by Walker et al. 1990 Nature 347:780-782. The movie shows the motility of two doublet-MT complexes. Ncd moves on the MT lattice towards the minus end since a doublet-MT complex moves in a plus-end direction over the immobilized Ncd on the coverslip. Ncd rotates the MTs clockwise when they are viewed from the axoneme doublet towards the plus ends. This clockwise rotation is best seen by advancing the movie one frame at a time and observing the movement of the minus ends of the curved doublets. During each rotation of the MT, the minus ends of the curved doublets are rotated into the solution and out of the plane of focus at the coverslip surface. Occasionally, as shown by the doublet-MT complex on the right, the curved doublet is unable to rotate across the coverslip surface, but translocation continues without rotation. When rotation is not inhibited, it occurred at a frequency of about 3.3 rotations for every 1 micrometer of forward movement. Time (min:sec) is given in the lower left hand corner of the video frame. The curved doublet on the left is about 2 microns long.
Contributed by Ted Salmon (tsalmon@email.unc.edu)
Wild-type larval locomotion
This is a Drosophila melanogaster third instar larva crawling along normally on the surface of an agar plate. Anterior is to the left where the dark mouth parts are distinguishable in the head. Notice the complex waves of contraction, flowing from posterior to anterior, that propel the larva forward. This locomotion is accomplished by the controlled contraction of layers of muscles attached to the cuticle within each body segment. Controlling this complex pattern of muscle contractions are motor neurons. The cell bodies of larval motor neurons are located in a ventral ganglion in the anterior-most third of the animal. The motor axons extend from the ventral ganglion in segmental nerves to innervate all the body wall musculature.
Khc mutant larval locomotion
This Drosophila melanogaster third instar larva has mutations in both copies of its kinesin heavy chain gene (Khc). (The genotype is Khc6/Df(2R)Jp6). Notice the posterior end of the animal is curved and flips upward. Mutations in Khc cause organelle jams that disrupt fast axonal transport in larval segmental nerves (Hurd and Saxton 1996 Genetics 144:1075-85). An ensuing differential loss of neuron function causes asymmetric muscle contractions in posterior segments that produce these rhythmic upward flips of the tail during crawling.
Contributed by MaryAnn Martin, Daryl Hurd & Bill Saxton
Melanosomes moving on a microtubule carpet in vitro
This sequence shows pigment granules, or melanosomes, from Xenopus melanophores moving on a microtubule carpet in vitro. Melanosomes possess motor proteins capable of transport both towards the plus and minus ends of microtubules. Differential regulation of these motors allows the melanophore either to aggregate its pigment at the center of the cell or disperse its pigment throughout the cytoplasm.
Contributed by Steve Rogers & Volodya Gelfand
Ncd-GFP during mitosis in living embryos
Mitotic spindles in an early embryo of Drosophila decorated with the Ncd microtuble motor protein fused to the green fluorescent protein (GFP) of the jellyfish, Aequorea victoria. The Ncd-GFP fusion protein localizes to spindle microtubules and can be used to follow divisions in live embryos, as seen in the movie sequence. The spindles are in metaphase/anaphase of cycle 9. Click here for further examples of Ncd, both wild type and mutant, fused to GFP and visualized in live embryos.
Contributed by Sharyn Endow
Cartoon animation of kinesin ‘walking’ on a microtubule
Created by Hong Yun Wang
Return to the Kinesin Movie Page.
Copyright 1996-2003. All rights reserved.
Created 5 October 1996 4:00 GMT
Modified 29 October 2004 20:01 GMT
