Name: Mounting and Image Acquisition of Drosophila Larval Microtubules
Uploaded: 2023-10-20T14:00:00
Description: Watch this Scientific Journal Video about Mounting and Image Acquisition of Drosophila Larval Microtubules at JoVE.com

mounting and image acquisition of drosophila larval microtubules

Viewing Microtubule Networks in Drosophila Neuromuscular Junctions and Muscle Cells

Microtubules (MTs), as one of the structural components of the cytoskeleton, play an important role in diverse biological processes, including cell division, cell growth and motility, intracellular transport, and the maintenance of cell shape. Microtubule dynamics and function are modulated by interactions with other proteins, such as MAP1, MAP2, Tau, Katanin, and Kinesin1,2,3,4,5.
In neurons, microtubules are essential for the development and maintenance of axons and dendrites. Abnormalities in microtubules lead to dysfunction and even the death of neurons. For instance, in the brain of Alzheimer&#39;s patients, Tau protein hyperphosphorylation reduces the stability of the microtubule network, causing neurological irregularities6. Thus, examining microtubule networks will contribute to a comprehension of neurodevelopment and the pathogenesis of neurological diseases.
The neuromuscular junction (NMJ) is the peripheral synapse formed between a motor neuron axon terminal and a muscle fiber, which is an excellent and powerful model system for studying synaptic structure and functions7. Futsch is a protein in Drosophila that is homologous to the microtubule-binding protein MAP1B found in mammals8. It is expressed only in neurons and plays a role in the development of the NMJ&#39;s synaptic buttons8,9. In wild-type, filamentous bundles that run along the center of NMJ processes are visualized by immunostaining with anti-Futsch. When reaching NMJ&#39;s end, this bundle has the ability to either form a loop consisting of microtubules or to lose its filamentous structure, resulting in a diffuse and punctate appearance10. Microtubule loops are associated with paused growth cones, which suggests the microtubule array is stable11. Therefore, we can indirectly determine the stable microtubule development in NMJ by Futsch staining. The large size of muscle cells in Drosophila larva allows for clear visualization of the microtubule network. The factors affecting the stability of the microtubule network can be found by analyzing the density and shape of microtubules. Simultaneously, the microtubule network status of muscle cells can be cross-verified with the result of NMJ to obtain more comprehensive conclusions.
Many protocols have been employed for investigating the network and dynamics of microtubules. However, these researches have often focused on in vitro studies12,13,14,15,16. Alternatively, some in vivo experiments have employed electron microscopy to detect the cytoskeleton17. According to the specific binding of fluorescently labeled antibodies or chemical dyes to proteins or DNA, the methods presented here allow the detection of microtubule networks in NMJ at the level of individual neurons in vivo, with results corroborated by observations in muscle cells. This protocol is simple, stable, and repeatable when combined with the powerful genetic tools available in Drosophila melanogaster, enabling a diverse range of phenotypic examinations and genetic screenings for the role of microtubule network regulatory proteins in the nervous system in vivo.

Author Spotlight: Understanding Microtubule Network in Drosophila Neuromuscular Junctions 

Using Drosophila Larval Neuromuscular Junction and Muscle Cells to Visualize Microtubule Network

Currently, microtubule dynamics are observed indirectly through microtubule-binding proteins such as EB1. Since alphabeta tubulin heterodimers are abundant in the cytoplasm, fold directly, neighboring tubulin heterodimers are lacking the dynamics of microtubule networks in vivo. Our protocol visualizes microtubules in neuromuscular synapses and muscle cells.When combined with the powerful genetic tools available in Drosophila melanogaster, enabling a diverse range of phenotypic examinations and the genetic screening for the role of microtubule network regulatory proteins in the nervous system in vivo. Our research focuses on the relationship between the cytoskeleton and the neurodevelopment, as well as its implications for neurological diseases. We hope to discover the mechanism of neurodevelopment and the parthenogenesis for neurological diseases by highlighting the effect of cytoskeletal regulatory proteins on neurons.

Watch this Scientific Journal Video about Mounting and Image Acquisition of Drosophila Larval Microtubules at JoVE.com

Mounting and Image Acquisition of Drosophila Larval Microtubules

Begin by placing the antibody labeled drosophila larval carcasses in 0.2%PBST on a glass slide. Adjusted under the stereo microscope, ensuring that the inner surface of the larval carcass is facing up. Absorb the excess PBST solution using a wipe.Then delicately add a drop of Anti-Fade mounting medium. Next place a cover slip on the slide covering the dissected larvae slowly and gently, avoiding bubble formation. Secure the cover slip in place by applying fingernail polish around its edges.Store the slide in a dark location to minimize fluorescent attenuation. For image acquisition, use the laser scanning confocal microscope with the 63x Oil immersion objective. Then adjust the wavelength and laser power to fit the requirements of the experiment best.To identify the neuromuscular junctions and capture images of muscle four in segment A three, select a 488 nanometer laser to activate alpha tubulin or Futsch, and 546 nanometers to activate the HRP imaging track. Modify the parameters to achieve a frame size of 1, 024 by 1, 024 pixels, a digital zoom of 1.0, and an imaging interval of 0.8 micrometers. To visualize microtubules in the muscle, capture images of muscle two in the segments A three to A five as it has fewer tracheal branches.Choose a 488 nanometer laser for activating alpha tubulin and a 633 nanometer laser for activating the T3605 imaging track. Adjust the imaging parameters to a frame size of 1, 024 by 1, 024 pixels, a digital zoom of 2.0, and an imaging interval of 0.4 micrometers. Both pre-and post-synaptic microtubule organizations of the neuromuscular junction were labeled with anti-alpha tubulin.Futsch staining reflected the abundance of stable microtubules in the pre-synaptic neurons. Decreased signal intensity of anti-Futsch was observed when microtubules severing protein Katanin 60 was overexpressed in the presynaptic neurons. The staining intensity of the axon trunk was stronger than that of the branches.Katanin 60 mutations resulted in increased microtubule loops. Overexpression of Katanin 60 caused short microtubule fragments within the terminal buttons. Alpha tubulin staining demonstrated a clear network of microtubules around the nucleus.Muscle cells had a significantly increased perinuclear microtubular intensity and exhibited stronger bundles in the Katanin 60 mutant. Overexpression resulted in fragmentation of the microtubule fibers.