USDA-ARS Research Project number 6036-22000-028-00D. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the United States Department of Agriculture or the Agriculture Research Service of any product or service to the exclusion of others that may be suitable. Additionally, the University of Florida Biology Department-Lewis and Varina Vaughn Fellowship in Orchid Biology (2017), and a University of Florida Graduate Research Fellowship (2014-2018) provided funding as well. We also thank Cindy Bennington from Stetson University for the orchid plant used during filming of this video.

NOTE: Perfumes or scented lotions and products must not be worn during any of these procedures.
1. Flower selection
NOTE: Flowers used can be either naturally growing in the environment or kept under artificial environmental conditions. Temperature, humidity, and light level during collection can vary based on the specific flower species used, and what type of data is being collected. For example, data has been collected during the day and at night for the same flower to determine if fragrance varies over time of day, and collected from both in situ and greenhouse flowers.
<ol>
	<li>Select a flower that is initially unopened, to standardize sample collection time. This controls for a flower changing fragrance over time.</li>
	<li>Depending on the duration of the blooming time, if possible, wait at least 24 hours after blooming to collect the sample, setting a standard time for all samples.</li>
	<li>If there are multiple blooming flowers on a plant, mark the one that will be used with flagging tape or something similar to ensure repeated sampling of the same flower.</li>
</ol>
2. Material preparation
<ol>
	<li>Use oven bags (approximately 40.5 cm &#215; 44.5 cm) and corrugated PTFE tubing.</li>
	<li>Initially, boil oven bags in water for ~30 min to remove residual plastic compounds. To dry, bake in an oven at 175 &#176;C.</li>
	<li>Once the bags have dried, add a polypropylene bulkhead union to each corner of the closed end of the oven bags. These attachments allow connection of tubes to push charcoal filtered air in and pull fragrance out of the headspace.</li>
	<li>Rinse all bags and tubes with 75% ethanol. Let both air dry after rinsing.</li>
	<li>After the oven bags have dried, bake bags and tubes in an oven at low heat, approximately 74-85 &#176;C for 30 min.</li>
</ol>
3. Volatile collection
NOTE: Sterile neoprene gloves need to be worn throughout this process, as contacting the bag or filter cartridges can contaminate the samples.
<ol>
	<li>Cover the selected flower with a baked oven bag. Cinch the bag together tightly with a plastic zip tie below the flower to prevent unwanted airflow into the bag.</li>
	<li>Attach a tube from the air outlet of the collection equipment and connect it to one of the bulkhead unions on the oven bag.</li>
	<li>On the other bulkhead union, attach a glass filter cartridge containing porous polymer adsorbent.</li>
	<li>Attach a second tube to the collection equipment on the vacuum input. Connect end of the second tube onto the glass volatile collection filter cartridge.</li>
	<li>Turn on both the air pump and vacuum at the same time set at ~0.05 L/min. The headspace around the flower will fill with air, but not become overinflated. The system will pull air from the bag through the filter, trapping the floral volatiles.</li>
	<li>Allow the machine to run for 10 min and then turn off both the air pump and vacuum. 
	NOTE: Flower species that produce/emit a smaller amount of fragrance may need to be sampled for a longer period of time.</li>
	<li>Disassemble the tubes and the glass filter cartridge. Place the filter into a glass vial with a screw-on cap. Once the cap is on, seal the vial with PTFE pipe thread tape.</li>
	<li>Store samples in a freezer until analyzed using GC-MS.</li>
	<li>Repeat this process with a clean oven bag and glass filter, this time with an empty oven bag, to collect a blank air sample as a control. This allows any background volatiles collected to be identified. 
	NOTE: Repeating sample collection needs to be done at approximately the same time each day, as some flowers produce varying fragrance levels over the course of a day.</li>
</ol>
4. GC-MS
<ol>
	<li>Remove the glass filter cartridge from the freezer and place into a GC-MS in the injector port.</li>
	<li>Release headspace volatiles collected on porous polymer adsorbent from the adsorbent by heating in the thermal collection trap (TCT) to 220 &#176;C for 8 min within a flow of helium gas (rate: 1.2 mL/min).</li>
	<li>Collect desorbed compounds in the TCT cold trap unit at -130 &#176;C. The cold trap temperature is regulated by the GC-MS program.</li>
	<li>Flash heat the TCT cold trap unit to inject the compounds into the capillary column of the gas chromatograph to which the TCT cold trap unit was connected. The method for the TCT begins at -20 &#176;C and ends at 150 &#176;C.</li>
	<li>Program the GC-MS to rise from 40 &#176;C to 280 &#176;C at 15 &#176;C/min, with a 5 min hold at 40 &#176;C.</li>
</ol>
5. Data analysis
<ol>
	<li>For identification, compare the mass spectra of the sample to those from mass spectra libraries (NIST and Department of Chemical Ecology, Goteborg University, Sweden11), as well as retention times of the volatiles to times of authentic compound standards12.</li>
	<li>Compare chromatograms of collected volatiles to identify common reoccurring peaks.</li>
	<li>After identifying the peak volatiles, use Pherobase (online database of semiochemicals and pheromones) to determine if they have been previously described in floral fragrances10.</li>
</ol>

<ol>
	<li>Knudsen, J. T., Tollsten, L., Bergstrom, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Floral+scents-+A+checklist+of+volatile+compounds+isolated+by+head-space+techniques.">Floral scents- A checklist of volatile compounds isolated by head-space techniques.</a> Phytochemistry. 33, 253-280 (1993).</li><li>Dudareva, N. A., Pichersky, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biology of floral scent. , (2006).</li><li>Altenburger, R., Matile, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rhythms+of+fragrance+emission+in+flowers.">Rhythms of fragrance emission in flowers.</a> Planta. 174, 242-247 (1988).</li><li>Dodson, C. H., Dressler, R. L., Hills, H. G., Adams, R. M., Williams, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biologically+active+compounds+in+orchid+fragrances.">Biologically active compounds in orchid fragrances.</a> Science. 164, 1243-1249 (1969).</li><li>Theis, N., Raguso, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+pollination+on+floral+fragrance+in+thistles.">The effect of pollination on floral fragrance in thistles.</a> Journal of Chemical Ecology. 31 (11), 2581-2600 (2005).</li><li>Heath, R. R., Manukian, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+evaluation+of+systems+to+collect+volatile+semiochemicals+from+insects+and+plants+using+a+charcoal-infused+medium+for+air+purification.">Development and evaluation of systems to collect volatile semiochemicals from insects and plants using a charcoal-infused medium for air purification.</a> Journal of Chemical Ecology. 18, 1209-1226 (1992).</li><li>Cancino, A., Damon, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+floral+fragrance+components+of+species+of+Encyclia+and+Prosthechea+(Orchidaceae)+from+Soconusco,+southeast+Mexico.">Comparison of floral fragrance components of species of Encyclia and Prosthechea (Orchidaceae) from Soconusco, southeast Mexico.</a> Lankesteriana. 6, 83-139 (2006).</li><li>Cancino, A., Damon, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fragrance+analysis+of+euglossine+bee+pollinated+orchids+from+Soconusco,+south-east+Mexico.">Fragrance analysis of euglossine bee pollinated orchids from Soconusco, south-east Mexico.</a> Plant Species Biology. 22, 129-134 (2007).</li><li>Sadler, J. J., Smith, J. M., Zettler, L. W., Alborn, H. T., Richardson, L. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fragrance+composition+of+Dendrophylax+lindenii+(Orchidaceae)+using+a+novel+technique+applied+in+situ.">Fragrance composition of Dendrophylax lindenii (Orchidaceae) using a novel technique applied in situ.</a> European Journal of Environmental Science. 1, 137-141 (2011).</li><li>Ray, H. A., Stuhl, C. J., Gillett-Kaufman, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Floral+fragrance+analysis+of+Prosthechea+cochleata+(Orchidaceae),+an+endangered+native,+epiphytic+orchid,+in+Florida.">Floral fragrance analysis of Prosthechea cochleata (Orchidaceae), an endangered native, epiphytic orchid, in Florida.</a> Plant Signaling and Behavior. , (2018).</li><li>. National Institute of Standards and Technology. U.S. Department of Commerce Available from: <a target="_blank" href="https://www.nist.gov/">https://www.nist.gov/</a> (2019)</li></ol>

The authors declare no conflicts of interest.

Though this technique is incredibly valuable for its sampling speed and portability, one limitation is using it for epiphytic species, or those growing on trees and not from the ground. In the original study10, one of the flowers sampled was epiphytic. Because the machine is too heavy to hang freely, a stable, elevated base must be made for sampling. Additionally, the machine can either be plugged in to an electrical outlet or battery powered, so if there is prolonged field sampling, there must be...

Flowers typically produce a fragrance used to attract pollinators. These fragrances are made up of many chemical compounds all acting together as a floral blend1,2,3. Without these fragrances, flowers would be less likely to pass on their genetic information using pollinators. Floral fragrance has been documented in many flowering plant families, with Orchidaceae being one of the more common families studied4. To understand the role of floral fragrance in pollination, it is important to nondestructively collect and analyze the chemical compounds being emitted from the flowers at different times of the day and during the several days to weeks the flower blooms are open, as fragrance can vary over time5.
An early protocol for this kind of sampling was developed by Heath and Manukian6. The goal of their sampling methods was to reduce stress on the specimen (e.g., plants, insects) being studied. Earlier papers documented that destructive procedures to the plant were required, such as removing blooming flowers in order to collect the fragrance. More recent floral fragrance publications by Cancino and Damon7,8 used similar methods. This study put the flowers in glass chambers and passed purified air over them; then fragrance compounds from the chamber were absorbed onto porous polymer adsorbents in clear Pasteur pipettes. The fragrances were collected for at least two hours during this study. Sadler et al.9 carried out floral fragrance studies on an epiphytic orchid in south Florida, much like the original study10. Again, this study required the flowers to be sampled for over two hours to collect the fragrance volatiles, with fragrance collected onto the porous polymer adsorbent. The paper here presents a non-destructive method that allows for much quicker sampling, lasting only 10 minutes. Also, instead of using a glass chamber oven baking bags are used, which allow for more flexible movement of the chamber and reduce the chances of damage to the flowers. These bags come in several sizes allowing the option to select the size of bag that will easily fit individual samples without damaging the sample or the surrounding material. The adsorbent used in this study was Tenax Porous Polymer Adsorbent. This differs from Porapak, because the sample can be thermally desorbed onto the GC-MS column for analysis, eliminating the use of a chemical solvent.
The methods in this study provide a way to quickly sample fragrance volatiles produced by flowers and could be used to sample volatiles from other specimens as well, such as insect pheromones, or mushroom volatiles. The reduced time for sampling means there is less stress on the sample and the ability to collect many samples in a short period of time. For example, in Sadler et al.9, the flower was only fragrant at night, so only two or three samples could be collected each night. With the method here, samples could be taken all night at 15-20-minute intervals from the same flower. Additionally, by using bags instead of glass chambers, the headspace can be suspended easier for sampling in the field for in situ collection on endangered or threatened plant species. Using the method presented here, we were able to sample flowers 1.5 to 2 meters above ground. These methods are incredibly useful for fragrance collection in the laboratory and the field, and provides researchers with a sampling technique that is fast and non-destructive to the sample.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Bulkhead Union</td>
			<td>Cole-Palmer</td>
			<td>UX-06390-10</td>
			<td></td>
		</tr>
		<tr>
			<td>FEP tubing</td>
			<td>Cole-Palmer</td>
			<td>UX-06407-60</td>
			<td></td>
		</tr>
		<tr>
			<td>Gas Chromatography</td>
			<td>Hewlett Packard</td>
			<td>6890</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Wool, Silanized</td>
			<td>Sigma-Aldrich</td>
			<td>20411</td>
			<td></td>
		</tr>
		<tr>
			<td>Inlet liner</td>
			<td>Agilent</td>
			<td>5062-3587</td>
			<td></td>
		</tr>
		<tr>
			<td>Mass Spectrometer</td>
			<td>Hewlett Packard</td>
			<td>5973</td>
			<td></td>
		</tr>
		<tr>
			<td>Reynolds oven bag</td>
			<td>Reynolds Consumer Products</td>
			<td>Turkey size</td>
			<td></td>
		</tr>
		<tr>
			<td>Tenax Porous Polymer Adsorbent</td>
			<td>Sigma-Aldrich</td>
			<td>11982</td>
			<td></td>
		</tr>
	</tbody>
</table>

rapid collection of floral fragrance volatiles using a headspace volatile collection technique for gc-ms thermal desorption sampling

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important step to conservation of flowers that are threatened or endangered. Because floral fragrance is critical for attracting pollinators, this method could be used to better understand or even enhance pollination. We present a protocol using a portable charcoal air filter and vacuum to collect floral fragrance volatiles, which are then analyzed by a GC-MS. By using this method, fragrance volatiles can be sampled using a non-destructive method with a machine that is easily transported. This methodology uses a rapid sampling procedure, cutting sampling time down from 2-3 hours to approximately 10 minutes. Using GC-MS, the fragrance compounds can be identified individually, based on authentic standards. The steps used for collecting fragrance and control data are presented, from material setup to collecting the data output.

Representative data from the GC-MS are shown as a chromatogram in Figure 1. In addition to the chromatogram, a data file of results is also provided (Supplementary File 1). This data file provides the retention time for each peak (RT), and an identification of what compound that peak is (Library/ID). Peaks between 10:00 and 15:00 minutes are floral volatiles, due to the molecular weight of the compounds10. The numbers above the peaks signify the reten...

Watch this Scientific Journal Video about Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling at JoVE.com

Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling

Here, we present a protocol for collecting the floral fragrance volatiles from blooming flowers, using a non-destructive sampling procedure.

Fragrances of many flower families have been sampled and the volatiles analyzed. Knowing the compounds that make up the fragrances can be an important ...

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Biochemistry

6.8K Views.  University of Florida. Here, we present a protocol for collecting the floral fragrance volatiles from blooming flowers, using a non-destructive sampling procedure.

Video: Rapid Collection of Floral Fragrance Volatiles using a Headspace Volatile Collection Technique for GC-MS Thermal Desorption Sampling

A Rapid Laser Probing Method Facilitates the Non-invasive and Contact-free Determination of Leaf Thermal Properties

Plants can produce valuable substances such as secondary metabolites and recombinant proteins. The purification of the latter from plant biomass can be streamlined by heat treatment (blanching). A blanching apparatus can be designed more precisely if the thermal properties of the leaves are known in detail, i.e., the specific heat capacity and thermal conductivity. The measurement of these properties is time consuming and labor intensive, and usually requires invasive methods that contact the sample directly. This can reduce the product yield and may be incompatible with containment requirements, e.g., in the context of good manufacturing practice. To address these issues, a non-invasive, contact-free method was developed that determines the specific heat capacity and thermal conductivity of an intact plant leaf in about one minute. The method involves the application of a short laser pulse of defined length and intensity to a small area of the leaf sample, causing a temperature increase that is measured using a near infrared sensor. The temperature increase is combined with known leaf properties (thickness and density) to determine the specific heat capacity. The thermal conductivity is then calculated based on the profile of the subsequent temperature decline, taking thermal radiation and convective heat transfer into account. The associated calculations and critical aspects of sample handling are discussed.

A method was developed to determine the specific heat capacity and thermal conductivity of leaf tissue by non-invasive, contact-free near infrared laser probing, which requires less than 1 min per sample.

Plants can produce valuable substances such as secondary metabolites and recombinant proteins. The purification of the latter from plant biomass can be ...

Mouse Adipose Tissue Collection and Processing for RNA Analysis

Compared to other tissues, white adipose tissue has a considerably less RNA and protein content for downstream applications such as real-time PCR and Western Blot, since it mostly contains lipids. RNA isolation from adipose tissue samples is also challenging as extra steps are required to avoid these lipids. Here, we present a procedure to collect three anatomically different white adipose tissues from mice, to process these samples and perform RNA isolation. We further describe the synthesis of cDNA and gene expression experiments using real-time PCR. The hereby described protocol allows the reduction of contamination from the animal's hair and blood on fat pads as well as cross-contamination between different fat pads during tissue collection. It has also been optimized to ensure adequate quantity and quality of the RNA extracted. This protocol can be widely applied to any mouse model where adipose tissue samples are required for routine experiments such as real-time PCR but is not intended for isolation from primary adipocytes cell culture.

The purpose of this paper is to present a step-by-step procedure to collect different white adipose tissues from mice, process the fat samples and extract RNA.

Compared to other tissues, white adipose tissue has a considerably less RNA and protein content for downstream applications such as real-time PCR and ...

Fully Autonomous Characterization and Data Collection from Crystals of Biological Macromolecules

High-brilliance X-ray beams coupled with automation have&#160;led to the use of synchrotron-based macromolecular X-ray crystallography (MX) beamlines for even the most challenging projects in structural biology. However, most facilities still require the presence of a scientist on site to perform the experiments. A new generation of automated beamlines dedicated to the fully automatic characterization of, and data collection from, crystals of biological macromolecules has recently been developed. These beamlines represent a new tool for structural biologists to screen the results of initial crystallization trials and/or the collection of large numbers of diffraction data sets, without users having to control the beamline themselves. Here we show how to set up an experiment for automatic screening and data collection, how an experiment is performed at the beamline, how the resulting data sets are processed, and how, when possible, the crystal structure of the biological macromolecule is solved.

Here, we describe how to use the automated screening and data collection options available at some synchrotron beamlines. Scientists send cryocooled samples to the synchrotron, and the diffraction properties are screened, the data sets are collected and processed and, where possible, a structure solution is carried out&#8212;all without human intervention.

High-brilliance X-ray beams coupled with automation have&#160;led to the use of synchrotron-based macromolecular X-ray crystallography (MX) beamlines for ...

Fixed Target Serial Data Collection at Diamond Light Source

Serial data collection is a relatively new technique for synchrotron users. A user manual for fixed target data collection at I24, Diamond Light Source is presented with detailed step-by-step instructions, figures, and videos for smooth data collection.

We present a comprehensive guide to fixed target sample preparation, data collection, and data processing for serial synchrotron crystallography at Diamond beamline I24.

Serial data collection is a relatively new technique for synchrotron users. A user manual for fixed target data collection at I24, Diamond Light Source is ...

Profiling Volatile Compounds in Blackcurrant Fruit using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography-Mass Spectrometry

There is an increasing interest in measuring volatile organic compounds (VOCs) emitted by ripe fruits for the purpose of breeding varieties or cultivars with enhanced organoleptic characteristics and thus, to increase consumer acceptance. High-throughput metabolomic platforms have been recently developed to quantify a wide range of metabolites in different plant tissues, including key compounds responsible for fruit taste and aroma quality (volatilomics). A method using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) is described here for the identification and quantification of VOCs emitted by ripe blackcurrant fruits, a berry highly appreciated for its flavor and health benefits.
Ripe fruits of blackcurrant plants (Ribes nigrum) were harvested and directly frozen in liquid nitrogen. After tissue homogenization to produce a fine powder, samples were thawed and immediately mixed with sodium chloride solution. Following centrifugation, the supernatant was transferred into a headspace glass vial containing sodium chloride. VOCs were then extracted using a solid-phase microextraction (SPME) fiber and a gas chromatograph coupled to an ion trap mass spectrometer. Volatile quantification was performed on the resulting ion chromatograms by integrating peak area, using a specific m/z ion for each VOC. Correct VOC annotation was confirmed by comparing retention times and mass spectra of pure commercial standards run under the same conditions as the samples. More than 60 VOCs were identified in ripe blackcurrant fruits grown in contrasting European locations. Among the identified VOCs, key aroma compounds, such as terpenoids and C6 volatiles, can be used as biomarkers for blackcurrant fruit quality. In addition, advantages and disadvantages of the method are discussed, including prospective improvements. Furthermore, the use of controls for batch correction and minimization of drift intensity have been emphasized.

A headspace solid-phase microextraction-gas-chromatography platform is described here for fast, reliable, and semi-automated volatile identification and quantification in ripe blackcurrant fruits. This technique can be used to increase knowledge about fruit aroma and to select cultivars with enhanced flavor for the purpose of breeding.

There is an increasing interest in measuring volatile organic compounds (VOCs) emitted by ripe fruits for the purpose of breeding varieties or cultivars ...

RIBO-seq in Bacteria: a Sample Collection and Library Preparation Protocol for NGS Sequencing

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of this method, in comparison to other approaches, is its ability to monitor translation by precisely mapping the position and number of ribosomes on a mRNA transcript.
In this article, we describe the consecutive stages of sample collection and preparation for RIBO-seq method in bacteria, highlighting the details relevant to the planning and execution of the experiment.
Since the RIBO-seq relies on intact ribosomes and related mRNAs, the key step is rapid inhibition of translation and adequate disintegration of cells. Thus, we suggest filtration and flash-freezing in liquid nitrogen for cell harvesting with an optional pretreatment with chloramphenicol to arrest translation in bacteria. For the disintegration, we propose grinding frozen cells with mortar and pestle in the presence of aluminum oxide to mechanically disrupt the cell wall. In this protocol, sucrose cushion or a sucrose gradient ultracentrifugation for monosome purification is not required. Instead, mRNA separation using polyacrylamide gel electrophoresis (PAGE) followed by the ribosomal footprint excision (28-30 nt band) is applied and provides satisfactory results. This largely simplifies the method as well as reduces the time and equipment requirements for the procedure. For library preparation, we recommend using the commercially available small RNA kit for Illumina sequencing from New England Biolabs, following manufacturer&#39;s guidelines with some degree of optimization.
The resulting cDNA libraries present appropriate quantity and quality required for next generation sequencing (NGS). Sequencing of the libraries prepared according to the described protocol results in 2 to 10 mln uniquely mapped reads per sample providing sufficient data for comprehensive bioinformatic analysis. The protocol we present is quick and relatively easy and can be performed with standard laboratory equipment.

Here we describe the stages of sample collection and preparation for RIBO-seq in bacteria. Sequencing of the libraries prepared according to these guidelines results in sufficient data for comprehensive bioinformatic analysis. The protocol we present is simple, uses standard laboratory equipment and takes seven days from lysis to obtaining libraries.

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of ...

Routine Collection of High-Resolution cryo-EM Datasets Using 200 KV Transmission Electron Microscope

Cryo-electron microscopy (cryo-EM) has been established as a routine method for protein structure determination during the past decade, taking an ever-increasing share of published structural data. Recent advances in TEM technology and automation have boosted both the speed of data collection and quality of acquired images while simultaneously decreasing the required level of expertise for obtaining cryo-EM maps at sub-3 &#197; resolutions. While most of such high-resolution structures have been obtained using state-of-the-art 300 kV cryo-TEM systems, high-resolution structures can be also obtained with 200 kV cryo-TEM systems, especially when equipped with an energy filter. Additionally, automation of microscope alignments and data collection with real-time image quality assessment reduces system complexity and assures optimal microscope settings, resulting in increased yield of high-quality images and overall throughput of data collection. This protocol demonstrates the implementation of recent technological advances and automation features on a 200 kV cryo-transmission electron microscope and shows how to collect data for the reconstruction of 3D maps that are sufficient for de novo atomic model building. We focus on best practices, critical variables, and common issues that must be considered to enable the routine collection of such high-resolution cryo-EM datasets. Particularly the following essential topics are reviewed in detail: i) automation of microscope alignments, ii) selection of suitable areas for data acquisition, iii) optimal optical parameters for high-quality, high-throughput data collection, iv) energy filter tuning for zero-loss imaging, and v) data management and quality assessment. Application of the best practices and improvement of achievable resolution using an energy filter will be demonstrated on the example of apo-ferritin that was reconstructed to 1.6 &#197;, and Thermoplasma acidophilum 20S proteasome reconstructed to 2.1-&#197; resolution using a 200 kV TEM equipped with an energy filter and a direct electron detector.

High-resolution cryo-EM maps of macromolecules can be also achieved by using 200 kV TEM microscopes. This protocol shows the best practices for setting accurate optics alignments, data acquisition schemes, and selection of imaging areas that are all essential for the successful collection of high-resolution datasets using a 200 kV TEM.

Cryo-electron microscopy (cryo-EM) has been established as a routine method for protein structure determination during the past decade, taking an ...

Single-Particle Cryo-EM Data Collection with Stage Tilt using Leginon

Single-particle analysis (SPA) by cryo-electron microscopy (cryo-EM) is now a mainstream technique for high-resolution structural biology. Structure determination by SPA relies upon obtaining multiple distinct views of a macromolecular object vitrified within a thin layer of ice. Ideally, a collection of uniformly distributed random projection orientations would amount to all possible views of the object, giving rise to reconstructions characterized by isotropic directional resolution. However, in reality, many samples suffer from preferentially oriented particles adhering to the air-water interface. This leads to non-uniform angular orientation distributions in the dataset and inhomogeneous Fourier-space sampling in the reconstruction, translating into maps characterized by anisotropic resolution. Tilting the specimen stage provides a generalizable solution to overcoming resolution anisotropy by virtue of improving the uniformity of orientation distributions, and thus the isotropy of Fourier space sampling. The present protocol describes a tilted-stage automated data collection strategy using Leginon, a software for automated image acquisition. The procedure is simple to implement, does not require any additional equipment or software, and is compatible with most standard transmission electron microscopes (TEMs) used for imaging biological macromolecules.

The present protocol describes a generalized and easy-to-implement scheme for tilted single-particle data collection in cryo-EM experiments. Such a procedure is especially useful for obtaining a high-quality EM map for samples suffering from preferential orientation bias due to adherence to the air-water interface.

Single-particle analysis (SPA) by cryo-electron microscopy (cryo-EM) is now a mainstream technique for high-resolution structural biology. Structure ...

Enhancing CO2 Sequestration: A Soil Biota Approach to Boost Mineral Weathering

Design and Construction of an Experimental Setup to Enhance Mineral Weathering through the Activity of Soil Organisms

Enhanced weathering (EW) is an emerging carbon dioxide (CO2) removal technology that can contribute to climate change mitigation. This technology relies on accelerating the natural process of mineral weathering in soils by manipulating the abiotic variables that govern this process, in particular mineral grain size and exposure to acids dissolved in water. EW mainly aims at reducing atmospheric CO2 concentrations by enhancing inorganic carbon sequestration. Until now, knowledge of EW has been mainly gained through experiments that focused on the abiotic variables known for stimulating mineral weathering, thereby neglecting the potential influence of biotic components. While bacteria, fungi, and earthworms are known to increase mineral weathering rates, the use of soil organisms in the context of EW remains underexplored. 
 This protocol describes the design and construction of an experimental setup developed to enhance mineral weathering rates through soil organisms while concurrently controlling abiotic conditions. The setup is designed to maximize weathering rates while maintaining soil organisms' activity. It consists of a large number of columns filled with rock powder and organic material, located in a climate chamber and with water applied via a downflow irrigation system. Columns are placed above a fridge containing jerrycans to collect the leachate. Representative results demonstrate that this setup is suitable to ensure the activity of soil organisms and quantify their effect on inorganic carbon sequestration. Challenges remain in minimizing leachate losses, ensuring homogeneous ventilation through the climate chamber, and avoiding flooding of the columns. With this setup, an innovative and promising approach is proposed to enhance mineral weathering rates through the activity of soil biota and disentangle the effect of biotic and abiotic factors as drivers of EW.

Author Spotlight: Unraveling the Role of Earthworms in Enhancing Mineral Weathering for CO2 Removal 

Here we present the construction and operation of an experimental setup to enhance mineral weathering through the activity of soil organisms while concurrently manipulating abiotic variables known to stimulate weathering. Representative results from the functioning of the setup and sample analyses are discussed together with points for improvement.

Enhanced weathering (EW) is an emerging carbon dioxide (CO2) removal technology that can contribute to climate change mitigation. This technology relies ...

Accelerating Macromolecular Structural Analysis Using Smart Leginon Autoscreen

Cryo-Electron Microscopy Screening Automation Across Multiple Grids Using Smart Leginon

Advancements in cryo-electron microscopy (cryoEM) techniques over the past decade have allowed structural biologists to routinely resolve macromolecular protein complexes to near-atomic resolution. The general workflow of the entire cryoEM pipeline involves iterating between sample preparation, cryoEM grid preparation, and sample/grid screening before moving on to high-resolution data collection. Iterating between sample/grid preparation and screening is typically a major bottleneck for researchers, as every iterative experiment must optimize for sample concentration, buffer conditions, grid material, grid hole size, ice thickness, and protein particle behavior in the ice, amongst other variables. Furthermore, once these variables are satisfactorily determined, grids prepared under identical conditions vary widely in whether they are ready for data collection, so additional screening sessions prior to selecting optimal grids for high-resolution data collection are recommended. This sample/grid preparation and screening process often consumes several dozen grids and days of operator time at the microscope. Furthermore, the screening process is limited to operator/microscope availability and microscope accessibility. Here, we demonstrate how to use Leginon and Smart Leginon Autoscreen to automate the majority of cryoEM grid screening. Autoscreen combines machine learning, computer vision algorithms, and microscope-handling algorithms to remove the need for constant manual operator input. Autoscreen can autonomously load and image grids with multi-scale imaging using an automated specimen-exchange cassette system, resulting in unattended grid screening for an entire cassette. As a result, operator time for screening 12 grids may be reduced to ~10 min with Autoscreen compared to ~6 h using previous methods which are hampered by their inability to account for high variability between grids. This protocol first introduces basic Leginon setup and functionality, then demonstrates Autoscreen functionality step-by-step from the creation of a template session to the end of a 12-grid automated screening session.

Author Spotlight: Enhancing Cryo-Electron Microscopy by Automated Data Collection and Analysis Techniques

Cryo-electron microscopy (cryoEM) multi-grid screening is often a tedious process that demands hours of attention. This protocol shows how to set up a standard Leginon collection and Smart Leginon Autoscreen to automate this process. This protocol can be applied to the majority of cryoEM holey foil grids.

Advancements in cryo-electron microscopy (cryoEM) techniques over the past decade have allowed structural biologists to routinely resolve macromolecular ...