This video demonstrates a detailed protocol for imaging membrane trafficking in transgenic Arabidopsis thaliana leaves using fluorescent proteins. It includes steps for sample preparation, setting up laser excitation, and capturing images and time series data to analyze the localization of ERL1 and MVBs in stomatal lineage cells.

sample preparation and confocal imaging of dual-colored f1 transgenic arabidopsis thaliana

Spatiotemporal Investigation of ERL1 Dynamics via Confocal Imaging

Membrane traffic is a conserved cellular process that distributes membrane components (also known as cargoes), including proteins, lipids, and other biological products, between different organelles within a eukaryotic cell or across the plasma membrane to and from the extracellular space1. This process is facilitated by a collection of membranes and organelles named the endomembrane system, which consists of the nuclear membrane, the endoplasmic reticulum, the Golgi apparatus, the vacuole/lysosomes, the plasma membrane, and multiple endosomes1. The endomembrane system enables the modification, packaging, and transport of membrane components using dynamic vesicles that shuttle between these organelles. Membrane trafficking events are crucial to cell development, growth, and environmental adaptation and, thus, are under stringent and complex regulation2. Currently, multiple approaches in molecular biology, chemical biology, microscopy, and mass spectrometry have been developed and applied to the field of membrane trafficking and have greatly advanced the understanding of the spatiotemporal regulation of the endomembrane system3,4. Molecular biology is used for classical genetic manipulations of the putative players involved in membrane trafficking, such as altering the gene expression of the protein of interest or labeling the protein of interest with certain tags. Tools in chemical biology include the usage of molecules that specifically interfere with the traffic of certain routes4,5. Mass spectrometry is powerful for identifying the components in an organelle that has been mechanically isolated by biochemical approaches3,4. However, membrane traffic is a dynamic, diverse, and complex biological process1. To visualize the membrane trafficking process in live cells under various conditions, light microscopy is an essential tool. Continuous progress has been made in advanced microscope techniques to overcome the challenges in measuring the efficiency, kinetics, and diversity of the events4. Here, this study focuses on the widely adopted methodologies in chemical/pharmacological biology, molecular biology, and microscopy to study membrane trafficking events in a naturally simplified and experimentally accessible system, the stomatal developmental process.
Stomata are micropores on plant aerial surfaces that open and close to facilitate gas exchange between the inner cells and the environment6,7,8. Hence, stomata are essential for photosynthesis and transpiration, two events that are crucial for plant survival and growth. Stomatal development is dynamically adjusted by environmental cues to optimize the plant&#39;s adaptation to the surroundings9. Dating back to studies in 2002, the identification of the receptor protein Too Many Mouths (TMM) opened the door to a new era of investigating the molecular mechanisms of stomatal development in the model plant Arabidopsis thaliana10. After just a few decades, a classical signaling pathway has been identified. From upstream to downstream, this pathway includes a group of secretory peptide ligands in the epidermal patterning factors (EFP) family, several cell-surface leucine-rich-repeat (LRR) receptor kinases in the EREECTA (ER) family, the LRR receptor protein TMM, a MAPK cascade, and several bHLH transcription factors including SPEECHLESS (SPCH), MUTE, FAMA, and SCREAM (SCRM)11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26. Previous work indicates that one of the receptor kinases, ER-LIKE 1 (ERL1), demonstrates active subcellular behaviors upon EPF perception20. ERL2 also dynamically traffics between the plasma membrane and some intracellular organelles27. Blocking the membrane trafficking steps causes abnormal stomatal patterning, resulting in stomatal clusters on the leaf surface28. These results suggest that membrane traffic plays an essential role in stomatal development. This study describes a protocol to spatiotemporally investigate the ERL1 dynamics using protein-protein subcellular co-localization analysis combined with pharmacological treatment using some membrane trafficking inhibitors.

Author Spotlight: Image-Based Methods to Study Membrane Trafficking Events in Stomatal Lineage Cells  

Image-Based Methods to Study Membrane Trafficking Events in Stomatal Lineage Cells

This technique studies the membrane trafficking events in stomatal development, the micropores on plant aerial surface, to facilitate photosynthesis and the transpiration. Various techniques are used to study plant stomatal development. This includes molecular biology, cell biology or microscopy, chemical biology, mass spectrometry, biochemistry, and structural biology.Individual stomata form asynchronously. Each stoma is formed by three transcend cell fate transitions. So collecting enough stomata lineage cells at a particular cell fate is one of the big challenges.Membrane trafficking is essential for cell survival and growth. Stomata lineage cell is no exception. This protocol addresses the commonly used approach to study membrane trafficking events in stomata lineage cells.Plants face challenging environment in the face of climate change. Stomata are passages for plant gas exchange, and are highly flexible to environmental stress for adaptation. We are interested in studying how abiotic stress affects the stomata development by focusing on the membrane trafficking of certain proteins in stomata lineage cells.

Watch this Scientific Journal Video about Sample Preparation and Confocal Imaging of Dual-Colored F1 Transgenic Arabidopsis thaliana at JoVE.com

Sample Preparation and Confocal Imaging of Dual-Colored F1 Transgenic Arabidopsis thaliana   

Sample Preparation and Confocal Imaging of Dual-Colored F1 Transgenic Arabidopsis thaliana

To begin the sample preparation, dissect the true leaf from the pharmacologically treated Arabidopsis thaliana transgenic sample using a sharp razor blade. Place the true leaf on a glass slide in a drop of water with the abaxial side up. Slowly cover the true leaf with a cover slip without air bubbles.For imaging, set up the beam path by selecting a 514-nanometer laser for yellow fluorescent protein, or YFP excitation. Obtain high image quality by using high laser power. Turn on PMT or HYD and define the upper and lower emission band thresholds based on the spectrum for the YFP fluorophore.Set a detection window of 530 to 570 nanometers to collect the YFP signal. for the sequential image of the second color, click on the seek button and add a new channel. In seek two, select a 555-nanometer laser for the red fluorescent protein, or RFP excitation, and set a detection window of 570 to 630 nanometers to collect the RFP signal.Select a 63X, 1.2W core lens on the system for imaging the subcellular membrane traffic activity within stomatal precursor cells. Start the format with an image size of 1024 by 1024 pixels, then optimize it based on the zoom factor and the objective settings for a good resolution. Next, set up the speed of the scan head, starting with a speed of 400 hertz, and optimize this based on the specific situation of the samples.To zoom on a region of interest without changing the objective lens, enter a zoom factor of one and optimize this based on the specific needs of the experiment. The line average refers to the number of times each X line will be scanned to obtain an average result. Start with a 2X line average For imaging the membrane trafficking events and optimize as needed.select the XYT scan mode in the acquisition mode to enable the time series utility. Next, select the waiting period between the time points under time interval. Define the number of frames to be collected by selecting frames.Use the Z-stack scan mode with the maximum intensity projection to collect the three-dimensional information regarding the membrane trafficking event within The entire cell. Then select the XYZ scan mode in acquisition mode and then the Z-stack utility will become accessible. Select the Z wide option.Under the scan mode, define the Z stack's top and bottom images using the begin and end buttons. Next, define the thickness of the Z step by clicking on the Z step size. To process the image, click on the primary process tab in Confocal software.Under the open projects tab on the far left side, select the interested Z-stack file. Then, in the middle tab named process tools, select the projection function. Choose maximum in the dropdown panel of method and click on the apply button.A Z-stack projection image will be generated under the open projects tab. To generate the video from the time series images, click the file tab in Fiji software and open function to open all the time series images one by one in the correct order. Alternatively, drag the images onto image J to open the data in the correct order.Then find the stack function in the image tab and choose images to stack to generate a video. Once done, save the file in the avi format with the desired frame rate. In the true leaf of seven-day-old transgenic plants bearing ERL1 promoter ERL1 YFP, scattered cells were highlighted by the YFP signal where ERL1 YFP labeled the plasma membrane.Multiple punctate signals were also observed, suggesting that ERL1 was also localized to the endosomes. RFP Ara7 highlighted multiple punctate signals in almost all the cells, indicating the multivesicular bodies, or MVBs, in these cells. When RFP Ara7 merged with the ERL1 YFP signal, most punctates overlapped, suggesting that some ERL1 YFP molecules were transported to the MVBs.Time series of true leaves bearing ERL1 YFP and MVB marker protein RFP Ara7 showed that YFP-labeled endosomes moved together with RFP Ara7 within the stomatal lineage cells. It confirmed that ERL1 YFP was localized to the multivesicular bodies.

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Research

JoVE Journal

Biology

68 Görüntüleme.  Rutgers University. Numune hazırlamaya başlamak için, keskin bir tıraş bıçağı kullanarak farmakolojik olarak işlenmiş Arabidopsis thaliana transgenik numunesinden gerçek yaprağı inceleyin. Gerçek yaprağı, abaksiyal tarafı yukarı bakacak şekilde bir damla suya bir cam slayt üzerine yerleştirin. Gerçek yaprağı hava kabarcığı olmayan bir kapak kayma ile yavaşça örtün.Görüntüleme için, sarı floresan proteini veya YFP uyarımı için 514 nanometrelik bir lazer seçerek ış...