We thank the U.S. Geological Survey Hammond Bay Biological Station for the use of their research facilities and the staff of U.S. Fish and Wildlife Service and Fisheries and Oceans Canada for providing sea lampreys. This research was supported by grants from the Great Lakes Fishery Commission to Weiming Li and Ke Li.

All methods described here have been approved by the Institutional Animal Care and Use Committee of Michigan State University (AUF# 03/14-054-00 and 02/17-031-00).
1. Collection and Extraction of Sea Lamprey Conditioned Water
<ol>
	<li>Place sexually mature male sea lampreys (15 - 30 animals) in a tank supplied with 250 L of aerated Lake Huron water maintained at 16 - 18&#160;&#176;C.</li>
	<li>Collect the male-conditioned water throughout each night from June to July. 
	Note: Sea lampreys naturally die after spawning. If a fish is nearing this point in its life, replace it with a fresh mature male.</li>
	<li>Extract the conditioned water by solid phase extraction.
	<ol>
		<li>Soak the resin in methanol for 4 h before loading it into a column. Load the resin into the column, then pump 10 L of water through the column to eliminate the organic solvent.</li>
		<li>Pass the conditioned water from the tank holding the fish via the pumping system to the top of the column. The water passes through a bed of 2 kg of moderately polar polymeric ion-exchange resin (e.g., Amberlite XAD-7 HP resin), contained in a series of four 2.5 L-capacity glass columns. Maintain load speeds between 400 and 600 mL/6 min. Elute the metabolites with 10 L of methanol followed immediately by 5 L of acetone. 
		CAUTION: This step uses methanol and acetone. Both are flammable and poisonous. 
		Note: The pooled residual can be stored at -80 &#176;C until further processed.</li>
	</ol>
	</li>
	<li>Reactivate the column after 1 week of enrichment by washing it with water (approximately 10 L).</li>
	<li>Remove the organic solvent (the mixture of methanol and water) and harvest the extract by rotatory evaporation for 5 h under reduced pressure (under 300 mbar) at 40 &#176;C. Concentrate the water residue by freeze dryer lyophilization for 48 h at -20 &#176;C until dry.</li>
</ol>
2. Isolation of Fraction Pools with Chromatography
<ol>
	<li>Soak the silica gel (230 - 400 mesh) in the initial mobile phase for 30 min. Transfer the gel with the solvent (suspension) to a glass column. Open the valve of the column to allow the mobile phase to go through. Allow the silica gel to precipitate and form a silica gel bed.</li>
	<li>Mix the extracts with silica gel (70 - 230 mesh) thoroughly and load them into the liquid chromatography column over the silica gel bed. Elute them with a gradient from 95% CHCl3 (chloroform)/MeOH (methanol) to 100% MeOH, 2.5 L in total volume. Collect the eluent in individual vials (each 10 ml). 
	CAUTION: The chloroform used in this step is a poisonous reagent.</li>
	<li>Guide the pooling of the eluents into 20 fractions by a thin layer chromatography (TLC) analysis.
	<ol>
		<li>Perform the TLC experiment on pre-coated silica gel plates by applying the sample on the starting line and immersing the starting line of the plate in the developing solvents (choose the polarity by the ratio of CHCl3 to methanol from 100 - 0%) in a sealed glass tank.</li>
		<li>Select the ratio of developing solvent to make all the TLC spots with a retention factor (Rf) ranging from 0.3 - 0.8.</li>
		<li>After the developing solvent reaches the end line, take the plate out of the tank, and wait 10 min for the solvent to evaporate.</li>
		<li>Visualize the spots first under UV light at 254 nm and then stain them by spraying them with an acidic methanol solution of 5% anisaldehyde (20 &#956;L) by a chromatography sprayer and heating them at 85 &#176;C for 3 min. 
		Note: The colorful spots on the TLC plate indicate the main component in the fraction.</li>
		<li>Combine the eluent to 20 fractions based on the spot color and the Rf similarity of the main component.</li>
	</ol>
	</li>
	<li>Concentrate the fraction to a residue by rotatory evaporation under reduced pressure (300 mbar according the property of solvents) at 40 &#176;C for approximately 30 min.</li>
</ol>
3. Electro-olfactogram (EOG) Recordings to Identify Odorous Fractions/Compounds
<ol>
	<li>Pull borosilicate glass capillaries (outer diameter: 1.5 mm; inner diameter: 0.86 mm; length: 100 mm) with a micropipette puller with the heater level set to 65.</li>
	<li>Score and cut the opening at the tip of the capillary with a diamond-tipped glass cutter and fill it with molten 0.4% agar in 0.9% saline. The opening at the tip of the capillary should be around 10 &#181;m in diameter.</li>
	<li>Fill the pulled capillary electrodes from steps 3.1 - 3.2 and solid-state electrodes holders pre-fabricated with Ag/AgCl pellets (see Table of Materials) with 3 M KCl using a micropipette. 
	Note: Dislodge any air bubbles in the capillary or the electrode holder.</li>
	<li>Insert the pulled electrodes in the electrode holders.</li>
	<li>Prepare 100 mL of 10-5 M L-arginine in charcoal-filtered water from a 10-2 M L-arginine stock solution in deionized water (stored at 4 &#176;C) in a volumetric flask. Transfer 20 mL of the 10-5 M L-arginine to a glass vial.</li>
	<li>For the concentration-response curve, prepare 10 mL of 10-fold dilutions of the fraction pools from step 2.3 in glass vials. Prepare fresh dilutions daily prior to the experiments and use them within a day. Put the glass vials of the working solutions of L-arginine and the fraction pool dilutions in a recirculating water bath to allow the temperature to equilibrate to 8 &#176;C.</li>
	<li>Anesthetize the lamprey with 3-aminobenzoic acid ethyl ester (MS222; 100 mg/L) and immobilize it with an intramuscular injection of gallamine triethiodide (3 mg/kg of body weight, in 0.9% saline) with a sterile syringe. 
	Note: A sufficient depth of anesthesia is determined by observing no gill motion, an inability to maintain an upright posture, and no suction to the sides of the tank using its oral disk. To minimize any microbial contamination before and during surgery, wear sterile gloves and soak the dissection tools in 70% ethanol (v:v) in deionized water for at least 10 min before use.</li>
	<li>Orient the anesthetized lamprey in a V-shaped stand and wrap it with a wet paper towel to prevent desiccation. 
	Note: Do not obstruct the gill openings.</li>
	<li>Insert a tube of recirculating aerated water containing 50 mg/L of MS222 into the buccal cavity, adjust the flow rate, and ensure that water is exiting via the gill openings to continuously irrigate the gills.</li>
	<li>Use a sterile scalpel and forceps [under the stereoscopic microscope at a 1.25X magnification (see Table of Materials)] to remove a 5 mm2 section of the skin on the surface of the olfactory capsule to expose the olfactory epithelium.</li>
	<li>Flush the odorant delivery tubing with filtered water and connect it to the valve mounted on a micromanipulator. Place the odorant delivery capillary tube into the olfactory epithelium cavity using the micromanipulator to deliver filtered water to the olfactory epithelium to prevent desiccation when not administering odorants.</li>
	<li>Mount the recording and reference electrodes on the micromanipulators. Lower the reference electrode onto the external skin near the naris. Using the stereoscopic microscope (1.25X), lower the recording electrode to barely touch the surface of the olfactory epithelium.</li>
	<li>Transfer the uptake of the odorant delivery tube from the background filtered water to the 10-5 M L-arginine solution.</li>
	<li>Turn on the computer, amplifier (set to DC mode), filter, and digitizer. Using the valve driver software, program the procedure to administer a 4 s single pulse of odorant by checking the box of T1, setting T to 4 s, and checking the box of T2.</li>
	<li>In the data acquisition software (see Table of Materials), set the acquisition mode to a high-speed oscilloscope, click the play icon, and then click Start in the valve driver to trigger the odorant pulse. 
	Note: The data acquisition software automatically records the differential EOG response amplitude for 20 s (3 s before, 4 s during the odorant pulse and 13 s afterward). Use the micromanipulator to maneuver the positions of the recording electrode, reference electrode, or odorant delivery tube to increase the signal-to-noise ratio with a maximum response to the L-arginine standard and a minimal response to the blank control (filtered water). Ground the amplifier by switching the AC-DC amplifier switch to GND while moving the electrodes.</li>
	<li>Start recording the blank control, L-arginine, and then the odorants prepared in step 3.6 from low to high concentrations with a 2 min flush of filtered water between applications.</li>
	<li>After recording responses to all the odorants to be tested, ground the amplifier and carefully retract the electrodes and odorant delivery capillary tube. Following the approved Institutional Animal Care and Use Committee (IACUC) methods, at the termination of the EOG experiment, euthanize the anesthetized lamprey with an overdose of MS222 (1 g/L). 
	Note: Verify successful euthanasia by noting a lack of gill movement and heartbeat for at least 5 min followed by pithing the brain.</li>
	<li>Analyze and plot the data using analysis software. Determine the threshold of detection of the odorants22 to identify odorous fractions that elicit responses greater than the blank water control. The fraction pools that elicit concentration-dependent olfactory responses that are different than the blank water control are then tested in a behavioral assay (step 4).</li>
</ol>
4. Two-choice Maze Behavioral Bioassay to Identify Behaviorally Active Fractions/Compounds
<ol>
	<li>Acclimate the sexually mature female sea lamprey in the release cage in the maze (see Supplementary Figure 1) for 5 min. Maintain the flow rate of the river water in the maze 
	Note: The maze is built from varnished marine grade wood and measures 6.5 m in length and 1.2 m in width with a divider measuring 2.7 m in length to separate the maze into two channels at the upstream end. Water is temporarily diverted into the maze. The water depth should be maintained at 0.19 m and the velocity should be maintained at 0.07 m/s &#177; 0.01.</li>
	<li>Release the sea lamprey and record the cumulative amount of time the lamprey spends in the experimental and control channel each containing river water for 10 min. 
	Note: If the sea lamprey fails to enter the experimental and control channel for at least 10 s during this 10 min period, end the trial, as this is an indication of inactivity or strong side bias.</li>
	<li>Apply the test stimulus (i.e., a putative pheromone at 10-12 M dissolved in 50% methanol/deionized water) to the randomly assigned experimental channel and the vehicle (50% methanol/deionized water) to the control channel using peristaltic pumps at constant rates of 200 mL/min for 5 min. 
	Note: The detection threshold concentration of the test stimulus as determined with the electro-olfactogram recordings should be used as the initial concentration for the behavioral test.</li>
	<li>Apply the test stimulus and the vehicle for an additional 10 min and record the cumulative amount of time the lamprey spends in the experimental and control channel.</li>
	<li>Flush the maze with water for 10 min before the start of the next trial. Repeat steps 4.1 - 4.4 with at least 7 lampreys if sufficient test stimulus is available.</li>
	<li>Calculate an index of preference22 for each trial and evaluate the significance using a Wilcoxon signed-rank test. 
	Note: The index results in a single number that can be either positive or negative. A positive value of the index of preference indicates attraction, whereas a negative value of the index of preference indications repulsion. If the index of preference is significantly different from zero, the fraction is deemed active. 
	<img alt="Equation" src="/files/ftp_upload/58059/58059eq1v2.jpg" /> 
	Here, 
	Bc = the time spent by the test lamprey in the control channel before the odorant application, 
	Be = the time spent in the experimental channel before the odorant application, 
	Ac = the time spent in the control channel after the odorant application, and 
	Ae = the time spent in the experimental channel after the odorant application.</li>
</ol>
5. Chromatographic Isolation of Pure Compounds from Active Fractions
<ol>
	<li>Repeat steps 2.1 - 2.4 with the fraction pools that induce olfactory responses (step 3) and elicit behavioral responses (step 4).</li>
	<li>Further purify the active fractions into compounds with size-exclusion chromatography using a Sephadex LH-20 column.
	<ol>
		<li>Prepare the sample in 0.5 mL in the initial mobile phase [CHCl3-MeOH (1:1) or MeOH 100%], load into the corresponding column a CHCl3-MeOH (1:1) column and then a MeOH (100%) column, and elute them to yield the compounds.</li>
	</ol>
	</li>
</ol>
6. Structure Elucidation of a Pure Compound with Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR)
<ol>
	<li>Dissolve and dilute the purified compound in the initial mobile phase (usually, methanol to water, 1:1, v:v) of high-performance liquid chromatography (HPLC) to form a 10 &#956;L solution of approximately 1 &#956;g/mL.
	<ol>
		<li>Transfer the sample solution to HPLC vials and set them into the autosampler of HPLC. Inject the sample (10 &#956;L) into the electrospray ionization mass spectrometry (ESIMS) and record the high-resolution electrospray ionization mass spectrometry (HRESIMS) spectra using a chromatography mass spectrometer23.</li>
	</ol>
	</li>
	<li>Predict the molecular formula according to the database in the mass spectrometer software (see Table of Materials)24.
	<ol>
		<li>Open the chromatogram of the injected sample and obtain its mass spectrum by selecting the chromatographic peak.</li>
		<li>Input the measured mass to ion (m/z) value (4 decimals) in Elemental composition under the Tool module. Set the tolerance parameter to PPM &#60; 5.</li>
		<li>Adjust the symbol parameters to fit the element composition of the measured molecule. The software produces a prediction of molecular formula based on the single mass analysis.</li>
	</ol>
	</li>
	<li>Select the deuterated solvents (600 &#956;L, CH3OH-d4 or DMSO-d6) according to the protocol25 to dissolve the samples.
	<ol>
		<li>Completely dissolve the sample in the selected deuterated solvents to form a solution with a concentration ranging approximately from 0.1 to 10 mg/mL. Transfer the sample solution into an NMR tube to record the 1D (1H, 13C) and 2D NMR [1H-1H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond correlation (HMBC)] spectra on a 900 MHz NMR spectrometer26.</li>
	</ol>
	</li>
	<li>Place the NMR tube with the sample inside the spinner turbine. Use the depth gauge to ensure the sample height is in the middle of the measuring window. Open the NMR software (see Table of Materials) and click the Lift button to change the sample in the magnet. 
	Note: Hold a hand over the top of the magnet to feel the gas coming from the top of the magnet. At the same time, a whistling sound should be audible.</li>
	<li>Gently place the sample on the air cushion on top of the magnet and push the Lift button again to descend the sample into the NMR magnet. 
	Note: Listen for a &#8220;click&#8221; noise to indicate the sample is in the right position.</li>
	<li>Create a new dataset and load the default parameters recommended by the NMR instrument (see Table of Materials).
	<ol>
		<li>Type &#8220;lock&#8221; to invoke the automatic locking procedure and select the solvent at the prompt page.</li>
		<li>For fine-tuning, in the Manipulate panel, adjust the button in the Unlock model, adjust the cursor on the manipulate panel, and lock the magnet again.</li>
		<li>On the prompt Atma page, adjust the parameter in the manipulate panel to the tuning procedure, which may take a few minutes. Wait until the tuning is completed to proceed.</li>
		<li>Start the automatic shimming routine by typing &#8220;topshim&#8221; in the prompt. Wait until the shimming is completed to proceed.</li>
		<li>Type &#8220;rga&#8221; to set automatic receiving gain adjustments, then type &#8220;d1&#8221; to set the delay between pulses, then type &#8220;zg&#8221; to start the acquisition, and wait until the acquisition finishes.</li>
		<li>Type &#8220;ef&#8221; or &#8220;efp&#8221; to process the data and then type &#8220;apk&#8221; for automatic phasing. Process the data on the NMR processing software.</li>
	</ol>
	</li>
	<li>Elucidate the chemical structure by an interpretation of the NMR data analysis.</li>
	<li>Count the carbon signals in the 13C NMR spectrum. Select the matched molecular formula from the predicted result in high-resolution mass spectrometry (HR-MS).</li>
	<li>Integrate the proton signals in the 1H NMR spectrum and assign the connectivity of the carbon- and proton-based on the signals in the HSQC spectrum.</li>
	<li>Assign the connectivity of the carbon skeleton based on the correlations in the 1H-1H COSY and HMBC spectrum.</li>
	<li>Tentatively assign the chemical structure based on the structure rationale27. Search the tentative structure in the chemical structure databases. Compare the tentative structure with the analogs in references.</li>
	<li>Assign the relative configuration with the Nuclear Overhauser Effect Spectroscopy (NOESY) spectrum. 
	Note: Since the identity properties of enantiomers displayed on spectrometry and spectroscopic methods are identical, the absolute configuration of some compounds, especially those with 2&#8217;-alcohol and 2&#8217;-NH2, has to be determined with a derivatization reaction. After the derivatization reaction, the differences indicated on the spectra facilitate the unequivocal assignment of the absolute configurations of most compounds28.</li>
</ol>
7. EOG and Bioassay to confirm pure compounds are odorous and behaviorally active
<ol>
	<li>Repeat steps 3.1 - 3.5.</li>
	<li>For the concentration-response curve, prepare 10 mL of 10-fold dilutions of the pure compounds from 10-6 M - 10-13 M of a 10-3 M pheromone stock solution in 50% methanol/water stored at -20 &#176;C based on the molecular weight determined in step 6.2. Put the glass vials with the working solutions of L-arginine and the pure compounds in a recirculating water bath to allow the temperature to equilibrate to 8 &#176;C.</li>
	<li>Repeat steps 3.7 - 3.18.</li>
	<li>Repeat steps 4.1 - 4.2.</li>
	<li>Apply the pure compound at the EOG detection threshold concentration to the randomly assigned experimental channel and the vehicle (50% methanol/deionized water) to the control channel using a peristaltic pump at constant rates of 200 mL/min for 5 min.</li>
	<li>Repeat steps 4.4 - 4.6.</li>
</ol>

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J., Pshenichnov, A., Tkachenko, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+&amp;#34;known+unknowns&amp;#34;+utilizing+accurate+mass+data+and+ChemSpider.">Identification of &amp;#34;known unknowns&amp;#34; utilizing accurate mass data and ChemSpider.</a> Journal of the American Society for Mass Spectrometry. 23 (1), 179-185 (2012).</li><li>Beckonert, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolic+profiling,+metabolomic+and+metabonomic+procedures+for+NMR+spectroscopy+of+urine,+plasma,+serum+and+tissue+extracts.">Metabolic profiling, metabolomic and metabonomic procedures for NMR spectroscopy of urine, plasma, serum and tissue extracts.</a> Nature Protocols. 2 (11), 2692 (2007).</li><li>Kaiser, B., Wright, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Draft Bruker XRF Spectroscopy User Guide: Spectral Interpretation and Sources of Interference. , (2008).</li><li>Breitmaier, E., Sinnema, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Structure Elucidation by NMR in Organic Chemistry: A Practical Guide. , (1993).</li><li>Seco, J. M., Quino&#225;, E., Riguera, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+assignment+of+absolute+configuration+by+NMR.">The assignment of absolute configuration by NMR.</a> Chemical Reviews. 104 (1), 17-118 (2004).</li><li>Li, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bile+Salt-like+Dienones+Having+a+Novel+Skeleton+or+a+Rare+Substitution+Pattern+Function+as+Chemical+Cues+in+Adult+Sea+Lamprey.">Bile Salt-like Dienones Having a Novel Skeleton or a Rare Substitution Pattern Function as Chemical Cues in Adult Sea Lamprey.</a> Organic Letters. , (2017).</li><li>Li, K., Buchinger, T. J., Li, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discovery+and+characterization+of+natural+products+that+act+as+pheromones+in+fish.">Discovery and characterization of natural products that act as pheromones in fish.</a> Natural Product Reports. , (2018).</li><li>Yambe, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=L-Kynurenine,+an+amino+acid+identified+as+a+sex+pheromone+in+the+urine+of+ovulated+female+masu+salmon.">L-Kynurenine, an amino acid identified as a sex pheromone in the urine of ovulated female masu salmon.</a> Proceedings of the National Academy of Sciences. 103 (42), 15370-15374 (2006).</li><li>Rasmussen, L., Lee, T. D., Zhang, A., Roelofs, W. L., Daves, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification,+identification,+concentration+and+bioactivity+of+(Z)-7-dodecen-1-yl+acetate:+sex+pheromone+of+the+female+Asian+elephant,+Elephas+maximus.">Purification, identification, concentration and bioactivity of (Z)-7-dodecen-1-yl acetate: sex pheromone of the female Asian elephant, Elephas maximus.</a> Chemical Senses. 22 (4), 417-437 (1997).</li><li>Sorensen, P. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mixture+of+new+sulfated+steroids+functions+as+a+migratory+pheromone+in+the+sea+lamprey.">Mixture of new sulfated steroids functions as a migratory pheromone in the sea lamprey.</a> Nature Chemical Biology. 1 (6), 324-328 (2005).</li><li>Hoye, T. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Details+of+the+structure+determination+of+the+sulfated+steroids+PSDS+and+PADS:+New+components+of+the+sea+lamprey+(Petromyzon+marinus)+migratory+pheromone.">Details of the structure determination of the sulfated steroids PSDS and PADS: New components of the sea lamprey (Petromyzon marinus) migratory pheromone.</a> The Journal of organic chemistry. 72 (20), 7544-7550 (2007).</li><li>Fine, J. M., Sorensen, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+biological+activity+of+the+multi-component+sea+lamprey+migratory+pheromone.">Isolation and biological activity of the multi-component sea lamprey migratory pheromone.</a> Journal of Chemical Ecology. 34 (10), 1259-1267 (2008).</li><li>De Buchinger, T. J., Wang, H., Li, W., Johnson, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+for+a+receiver+bias+underlying+female+preference+for+a+male+mating+pheromone+in+sea+lamprey.">Evidence for a receiver bias underlying female preference for a male mating pheromone in sea lamprey.</a> Proceedings of the Royal Society of London B: Biological Sciences. 280, (2013).</li><li>De Bruyne, M., Baker, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Odor+detection+in+insects:+volatile+codes.">Odor detection in insects: volatile codes.</a> Journal of Chemical Ecology. 34 (7), 882-897 (2008).</li><li>Bradshaw, J., Baker, R., Lisk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separate+orientation+and+releaser+components+in+a+sex+pheromone.">Separate orientation and releaser components in a sex pheromone.</a> Nature. 304 (5923), 265-267 (1983).</li><li>Linn, C., Campbell, M., Roelofs, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pheromone+components+and+active+spaces:+what+do+moths+smell+and+where+do+they+smell+it.">Pheromone components and active spaces: what do moths smell and where do they smell it.</a> Science. 237 (4815), 650-652 (1987).</li></ol>

The authors have nothing to disclose.

Fish live in a chemical world full of compounds yet to be identified. Bioassay-guided fractionation has proven essential to identify and characterize bioactive molecules that mediate many chemical interactions, such as those observed in masu salmon31, Asian elephants32, and sea lampreys33,34,35. Bioassay-guided fractionation is an effective approach to accurately trace and pinpoint...

Pheromones are specific chemical signals released by individuals that aid them in locating food sources, detecting predators, and mediating social interactions of conspecifics1. Pheromone communication in insects has been well studied2; however, the chemical identification and biological function of aquatic vertebrate pheromones have not been studied as extensively. Knowledge of the identity and function of the pheromones released can be applied to facilitate the recovery of threatened species3,4 or control pest species5,6. The application of these techniques necessitates the isolation and characterization of the bioactive pheromone components.
Pheromone identification is a branch of natural product chemistry. Progress in pheromone research has been partially limited due to the nature of the pheromone molecules themselves. Pheromones are often unstable and released in small quantities, and only a few sampling techniques exist to detect minute amounts of volatile7,8 or water-soluble compounds9. Approaches to identify pheromones include 1) a targeted screening of known compounds, 2) metabolomics, and 3) bioassay-guided fractionation. A targeted screening of known compounds tests commercially available metabolic by-products of physiological processes hypothesized to function as pheromones. This approach is limiting because researchers can only test known and available compounds. However, it has resulted in the successful identification of sex hormones in goldfish that function as pheromones10,11,12. Metabolomics is a second pheromone identification approach that distinguishes potential small molecule metabolic products within a biological system13. A comparison of the metabolic profiles of two groups (i.e., an active versus an inactive extract) enables the identification of a potential metabolic profile from which the metabolite is purified, the structure is elucidated, and the bioactivity is confirmed14. Additive or synergistic effects of complex formulations of specific mixtures are more likely to be detected with metabolomics because metabolites are considered together rather than as a series of fractions13. Yet, the implementation of metabolomics relies on the availability of synthetic references because the resulting data do not facilitate the elucidation of novel structures.
Bioassay-guided fractionation is an integrated, iterative approach that spans two fields: chemistry and biology. This approach uses the results of physiological and behavioral bioassays to guide the isolation and identification of an active pheromone compound. A crude extract is fractionated by a chemical property (i.e., molecular size, polarity, etc.) and tested with electro-olfactogram (EOG) recordings and/or in a bioassay. The bioactive components are screened out by repeating these steps of fractionation and EOGs and/or bioassays. The structures of pure active compounds are elucidated by spectrometric and spectroscopic methods, which provide the molecular weight and structural information to produce a template of the compound to be synthesized. Bioassay-guided fractionation can yield diverse metabolites and potentially novel pheromones with unique chemical skeletons that are unlikely to be predicted from the biosynthetic pathways.
Here, we describe the bioassay-guided fractionation protocol used to isolate and characterize the bioactivity of male sea lamprey sex pheromone compounds. The sea lamprey (Petromyzon marinus) is an ideal vertebrate model to study pheromone communication because these fish rely heavily on the olfactory detection of chemical cues to mediate their anadromous life history comprised of three distinct stages: larvae, juvenile, and adult. Sea lamprey larvae burrow into the sediment of freshwater streams, undergo a drastic metamorphosis, and transform into juveniles that migrate to a lake or ocean where they parasitize large host fish. After detaching from the host fish, the adults migrate back into spawning streams, guided by the migratory pheromones released by stream-resident larvae15,16,17,18,19. Mature males ascend to the spawning grounds, release a multi-component sex pheromone to attract mates, intermittently spawn for approximately a week, and then die15,20. The identification of sea lamprey pheromones is important because a modulation of the pheromone communication system is among the options considered to control the invasive sea lampreys in the Laurentian Great Lakes21.

<table><tbody><tr><td>Premium standard wall borosilicate capillaries with filament&amp;nbsp;</td><td>Warner Instruments</td><td>G150F-4</td><td>recording and reference electrode (OD 1.5 mm, ID 0.86 mm)</td></tr><tr><td>Pipette puller instrument</td><td>Narishige</td><td>PC-10</td><td>pulls electrodes for EOGs</td></tr><tr><td>Diamond-tipped glass cutter</td><td>Generic</td><td></td><td>cut tip of electrodes for EOG</td></tr><tr><td>Borosilicate glass capillaries</td><td>World Precision Instruments</td><td>1B150-4</td><td>odorant delivery tube for EOG</td></tr><tr><td>Recording electrode holder E Series straight body with Ag/AgCl pellet for glass capillary OD 1.5 mm</td><td>Warner Instruments</td><td>ESP-M15N</td><td>recording electrode holder</td></tr><tr><td>Reference electrode holder E Series with handle with&amp;nbsp; Ag/AgCl pellet&amp;nbsp; for glass capillary OD 1.5 mm</td><td>Warner Instruments</td><td>E45P-F15NH</td><td>reference electrode holder</td></tr><tr><td>1 mm pin</td><td>Warner Instruments</td><td>WC1-10</td><td>to bridge reference and recording electrode holders</td></tr><tr><td>2 mm pin</td><td>Warner Instruments</td><td>WC2-5</td><td>to bridge reference and recording electrode holders</td></tr><tr><td>Agar</td><td>Sigma</td><td>A1296</td><td>molten agar to fill electrodes</td></tr><tr><td>Potassium chloride (KCl)</td><td>Sigma</td><td>P9333</td><td>3M KCl to fill electrodes and electrode holders</td></tr><tr><td>Micropipette microfil</td><td>World Precision Instruments</td><td>MF28G-5</td><td>to fill electrodes and electrode holders</td></tr><tr><td>L-Arginine</td><td>Sigma</td><td>A5006</td><td>positive control odorant for EOG</td></tr><tr><td>Methanol</td><td>Sigma</td><td>34860</td><td></td></tr><tr><td>Water bath</td><td>Custom made</td><td>N/A</td><td>holds odorants for EOG</td></tr><tr><td>3-aminobenzoic acid ethyl ester (MS222)</td><td>Syndel USA</td><td>Tricaine1G</td><td>EOG anesthetic</td></tr><tr><td>Gallamine triethiodide</td><td>Sigma</td><td>G8134-5G</td><td>EOG paralytic</td></tr><tr><td>1 mL syringe</td><td>BD Biosciences</td><td>301025</td><td>to administer paralytic</td></tr><tr><td>Subcutaneous needle 26G 5/8</td><td>BD Biosciences</td><td>305115</td><td>to administer paralytic</td></tr><tr><td>Roller clamp</td><td>World Precision Instruments</td><td>14043-20</td><td>adjust flow rate of anesthic into lamprey&#039;s mouth</td></tr><tr><td>Sodium chloride (NaCl)</td><td>J.T. Baker</td><td>3624-05</td><td>for preparation of 0.9% saline</td></tr><tr><td>V-shaped plastic stand as specimen stage</td><td>Custom made</td><td>N/A</td><td>holds lamprey during EOG</td></tr><tr><td>Plastic trough</td><td>Custom made</td><td>N/A</td><td>holds V-shaped plastic stand during EOG</td></tr><tr><td>Scalpel Blades - #11</td><td>Fine Science Tools</td><td>10011-00</td><td>for EOG dissection</td></tr><tr><td>Scalpel Handle - #3</td><td>Fine Science Tools</td><td>10003-12</td><td>for EOG dissection</td></tr><tr><td>Straight ultra fine forceps</td><td>Fine Science Tools</td><td>11252-00</td><td>for EOG dissection, Dumont #5SF Forceps</td></tr><tr><td>Curved ultra fine forceps</td><td>Fine Science Tools</td><td>11370-42</td><td>for EOG dissection, Moria MC40B</td></tr><tr><td>Straight pring Scissors</td><td>Fine Science Tools</td><td>15003-08</td><td>for EOG dissection</td></tr><tr><td>Stereomicroscope</td><td>Zeiss</td><td>Discovery V8</td><td>for EOG dissection</td></tr><tr><td>Illuminator light</td><td>Zeiss</td><td>CL 1500 ECO</td><td>for EOG dissection</td></tr><tr><td>Plastic tubing</td><td>Generic</td><td></td><td>to connect re-circulating EOG setup and water baths</td></tr><tr><td>Odorant delivery tubing</td><td>Custom made</td><td>N/A</td><td></td></tr><tr><td>In line filter and gasket set</td><td>Lee Company</td><td>TCFA1201035A</td><td></td></tr><tr><td>Micromanipulators</td><td>Narishige</td><td>MM-3</td><td>to position electrodes and odorant delivery capillary tube</td></tr><tr><td>Magnetic holding devices</td><td>Kanetec</td><td>MB-K</td><td></td></tr><tr><td>Valve driver</td><td>Arduino</td><td>custom made</td><td>to control the opening of the valve for odor stimulation</td></tr><tr><td>Electromagnetic valve</td><td>Lee Company</td><td>LFAA1201618H</td><td>valve for odor stimulation</td></tr><tr><td>NeuroLog AC/DC amplifier</td><td>Digitimer Ltd.</td><td>NL106</td><td>to increase the amplitude of the elictrical signal</td></tr><tr><td>NeuroLog DC pre-amplifier with headstage</td><td>Digitimer Ltd.</td><td>NL102G</td><td>to increase the amplitude of the elictrical signal</td></tr><tr><td>Low-pass 60 Hz filter</td><td>Digitimer Ltd.</td><td>NL125</td><td></td></tr><tr><td>Digitizer</td><td>Molecular Devices LLC</td><td>Axon Digidata 1440A</td><td></td></tr><tr><td>Dell computer (OptiPlex 745) running Axoscope data acquistion software</td><td>Molecular Devices LLC</td><td>AxoScope version 10.4</td><td></td></tr><tr><td>Faraday cage</td><td>Custom made</td><td>N/A</td><td>Electromagnetic noise shielding</td></tr><tr><td>Two-choice maze</td><td>Custom made</td><td>N/A</td><td>waterproofed marine grade plywood covered with plastic liner</td></tr><tr><td>Trash pump</td><td>Honda</td><td>WT30XK4A</td><td>fills maze with water from nearby river</td></tr><tr><td>Peristaltic pump with tubing</td><td>Cole Parmer</td><td>Masterflex 07557-00</td><td>to adminster odorants in maze</td></tr><tr><td>Inverter Generator</td><td>Honda</td><td>EU1000i</td><td>powers perstaltic pump</td></tr><tr><td>Release cage</td><td>Custom made</td><td>N/A</td><td>used to acclimate lamprey in the maze</td></tr><tr><td>Mesh</td><td>Generic</td><td></td><td>used to contain the dimensions of the maze and minimize water turbulance with mesh rollers</td></tr><tr><td>Buckets (5 gallon)</td><td>Generic</td><td></td><td>to mix odorants</td></tr><tr><td>Flow meter</td><td>Marsh-McBirney</td><td>Flo-Mate 2000</td><td>to measure discharge</td></tr><tr><td>XAD 7 HP resin</td><td>Dow chemical</td><td>37380-43-1</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>Methanol</td><td>Sigma</td><td>34860</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>Water bath</td><td>Yamato</td><td>BM 200</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>Freeze dryer</td><td>Labconco</td><td>CentriVap Concentrator</td><td>for extraction of conditioned water</td></tr><tr><td>chloroform</td><td>Sigma</td><td>CX1050</td><td>for isolation of fraction pools</td></tr><tr><td>Silica gel 70-230 mesh</td><td>Sigma</td><td>112926-00-8</td><td>for isolation of fraction pools</td></tr><tr><td>Silica gel 230-400 mesh</td><td>Sigma</td><td>112926-00-8</td><td>for isolation of fraction pools</td></tr><tr><td>Pre-coated silica gel TLC plates</td><td>Sigma</td><td>99571</td><td>for isolation of fraction pools</td></tr><tr><td>anisaldehyde</td><td>Sigma</td><td>A88107</td><td>for isolation of fraction pools</td></tr><tr><td>Sephadex LH-20</td><td>GE Healthcare</td><td>17-0090-01</td><td>for isolation of fraction pools</td></tr><tr><td>Amberlite XAD 7 HP resin</td><td>Sigma</td><td>XAD7HP</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>4, 2.5L capacity glass columns</td><td>Ace Glass Inc.</td><td>5820</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>Acetone</td><td>Sigma</td><td>650501</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>TQ-S TOF LC Mass spectrometer (or equivalent)</td><td>Waters Co.</td><td>N/A</td><td>for structure elucidation</td></tr><tr><td>Binary HPLC pump</td><td>Waters Co.</td><td>1525</td><td>for isolation of fraction pools/compounds</td></tr><tr><td>Agilent NMR spectrometer, 900MHz (or equivalent)</td><td>Agilent</td><td>N/A</td><td>for structure elucidation</td></tr><tr><td>Rotovap drying system</td><td>Buchi</td><td>RII</td><td>for extraction of conditioned water&amp;nbsp;</td></tr><tr><td>UV lamp (254 nm)</td><td>Spectronics Co.</td><td>ENF-240C</td><td>for thin layer chromatography&amp;nbsp;</td></tr></tbody></table>

the identification of sea lamprey pheromones using bioassay-guided fractionation

Bioassay-guided fractionation is an iterative approach that uses the results of physiological and behavioral bioassays to guide the isolation and identification of an active pheromone compound. This method has resulted in the successful characterization of the chemical signals that function as pheromones in a wide range of animal species. Sea lampreys rely on olfaction to detect pheromones that mediate behavioral or physiological responses. We use this knowledge of fish biology to posit functions of putative pheromones and to guide the isolation and identification of active pheromone components. Chromatography is used to extract, concentrate, and separate compounds from the conditioned water. Electro-olfactogram (EOG) recordings are conducted to determine which fractions elicit olfactory responses. Two-choice maze behavioral assays are then used to determine if any of the odorous fractions are also behaviorally active and induce a preference. Spectrometric and spectroscopic methods provide the molecular weight and structural information to assist with the structure elucidation. The bioactivity of the pure compounds is confirmed with EOG and behavioral assays. The behavioral responses observed in the maze should ultimately be validated in a field setting to confirm their function in a natural stream setting. These bioassays play a dual role to 1) guide the fractionation process and 2) confirm and further define the bioactivity of isolated components. Here, we report the representative results of a sea lamprey pheromone identification that exemplify the utility of the bioassay-guided fractionation approach. The identification of sea lamprey pheromones is particularly important because a modulation of its pheromone communication system is among the options considered to control the invasive sea lamprey in the Laurentian Great Lakes. This method can be readily adapted to characterize the chemical communication in a broad array of taxa and shed light on waterborne chemical ecology.

A diagram summarizing the steps described in the protocol of the bioassay-guided fractionation is shown in Figure 1. The protocol involves steps to isolate and characterize the structure, the olfactory potency, and the behavioral activity of 5 putative sea lamprey pheromones (Figure 2). Using the mass spectrometric and NMR data (Figure 3 and Figure 4), the structures of ...

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The Identification of Sea Lamprey Pheromones Using Bioassay-Guided Fractionation

Here, we present a protocol to isolate and characterize the structure, olfactory potency, and behavioral response of putative pheromone compounds of sea lampreys.

Bioassay-guided fractionation is an iterative approach that uses the results of physiological and behavioral bioassays to guide the isolation and ...

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Biochemistry

8.9K Views.  Michigan State University. Here, we present a protocol to isolate and characterize the structure, olfactory potency, and behavioral response of putative pheromone compounds of sea lampreys.

Video: The Identification of Sea Lamprey Pheromones Using Bioassay-Guided Fractionation

A Fish-feeding Laboratory Bioassay to Assess the Antipredatory Activity of Secondary Metabolites from the Tissues of Marine Organisms

Marine chemical ecology is a young discipline, having emerged from the collaboration of natural products chemists and marine ecologists in the 1980s with the goal of examining the ecological functions of secondary metabolites from the tissues of marine organisms. The result has been a progression of protocols that have increasingly refined the ecological relevance of the experimental approach. Here we present the most up-to-date version of a fish-feeding laboratory bioassay that enables investigators to assess the antipredatory activity of secondary metabolites from the tissues of marine organisms. Organic metabolites of all polarities are exhaustively extracted from the tissue of the target organism and reconstituted at natural concentrations in a nutritionally appropriate food matrix. Experimental food pellets are presented to a generalist predator in laboratory feeding assays to assess the antipredatory activity of the extract. The procedure described herein uses the bluehead, Thalassoma bifasciatum, to test the palatability of Caribbean marine invertebrates; however, the design may be readily adapted to other systems. Results obtained using this laboratory assay are an important prelude to field experiments that rely on the feeding responses of a full complement of potential predators. Additionally, this bioassay can be used to direct the isolation of feeding-deterrent metabolites through bioassay-guided fractionation. This feeding bioassay has advanced our understanding of the factors that control the distribution and abundance of marine invertebrates on Caribbean coral reefs and may inform investigations in diverse fields of inquiry, including pharmacology, biotechnology, and evolutionary ecology.

This bioassay employs a model predatory fish to assess the presence of feeding-deterrent metabolites from organic extracts of the tissues of marine organisms at natural concentrations using a nutritionally comparable food matrix.

Marine chemical ecology is a young discipline, having emerged from the collaboration of natural products chemists and marine ecologists in the 1980s with ...

Environment

An Ultra-clean Multilayer Apparatus for Collecting Size Fractionated Marine Plankton and Suspended Particles

The distributions of many trace elements in the ocean are strongly associated with the growth, death, and re-mineralization of marine plankton and those of suspended/sinking particles. Here, we present an all plastic (Polypropylene and Polycarbonate), multi-layer filtration system for collection of suspended particulate matter (SPM) at sea. This ultra-clean sampling device has been designed and developed specifically for trace element studies. Meticulous selection of all non-metallic materials and utilization of an in-line flow-through procedure minimizes any possible metal contamination during sampling. This system has been successfully tested and tweaked for determining trace metals (e.g., Fe, Al, Mn, Cd, Cu, Ni) on particles of varying size in coastal and open ocean waters. Results from the South China Sea at the South East Asia Time-Series (SEATS) station indicate that diurnal variations and spatial distribution of plankton in the euphotic zone can be easily resolved and recognized. Chemical analysis of size-fractionated particles in surface waters of the Taiwan Strait suggests that the larger particles (&#62;153 &#181;m) were mostly biologically derived, while the smaller particles (10 - 63 &#181;m) were mostly composed of inorganic matter. Apart from Cd, the concentrations of metals (Fe, Al, Mn, Cu, Ni) decreased with increasing size.

Plankton and suspended particles play a major role in the biogeochemical cycles in the ocean. Here, we provide an ultra-clean, low stress method for the collection of various sizes of particles and plankton at sea with the capability of handling large volumes of seawater.

The distributions of many trace elements in the ocean are strongly associated with the growth, death, and re-mineralization of marine plankton and those ...

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles

Reptiles signal to conspecifics using lipids in their skin, primarily to enable mate tracking and assessment. The isolation of these lipids has utility in research focused on evolutionary patterns and mechanisms of chemical communication, in addition to understanding the waterproofing role of lipids in the evolution of terrestrial life. In an applied approach, such skin-based cues have potential use for wildlife managers dealing with invasive species. The main steps for quantifying reptile skin lipids in the protocol presented here include extraction, total lipid determination, and fractionation via column chromatography, the latter process resulting in purified eluates of compounds which can then either be analyzed to assign compound identifications (e.g., gas chromatography-mass spectrometry [GC-MS]) and/or used directly in more refined bioassays. Skin lipids can be extracted from living skin, shed skin, or dead whole animals, using nonpolar organic solvents (e.g., hexane, benzene, toluene). Extraction solubilizes the lipids and, then, the solvent can be evaporated to yield a measurable lipid-only extract. Fractionation involves the separation of the total lipid extract into specific eluates via traditional column chromatography. The total lipid extract is first bound to a substrate-based column (e.g., alumina) and, then, individual eluates (&#34;fractions&#34;) of solvent at specific volumes are passed sequentially through the column to elute sets of compounds from the lipid mixture based on common polarity. The fractions progress in polarity at a standardized sequence by increasing the relative amount of polar solvent (e.g., diethyl ether) in nonpolar solvent. In this manuscript, we describe several methods for extracting skin lipids of reptiles and, then, provide a standard protocol for isolating different sets of compounds based on polarity, using traditional column chromatography. Whole lipid extracts or specific fractions can, then, be used in bioassays to determine any biological activity elicited by the compounds therein.

In reptiles, skin lipids from conspecifics are crucial for sexual signaling, with potential use in invasive species management. Here, we describe protocols for extracting skin lipids from shed skin or whole animals, determining and analyzing the total lipid mass, and separating the lipids using fractionation via column chromatography.

Reptiles signal to conspecifics using lipids in their skin, primarily to enable mate tracking and assessment. The isolation of these lipids has utility in ...

Multi-Faceted Mass Spectrometric Investigation of Neuropeptides in Callinectes sapidus

Neuropeptides are signaling molecules that regulate almost all physiological and behavioral processes, such as development, reproduction, food intake, and response to external stressors. Yet, the biochemical mechanisms and full complement of neuropeptides and their functional roles remain poorly understood. Characterization of these endogenous peptides is hindered by the immense diversity within this class of signaling molecules. Additionally, neuropeptides are bioactive at concentrations 100x - 1000x lower than that of neurotransmitters and are prone to enzymatic degradation after synaptic release. Mass spectrometry (MS) is a highly sensitive analytical tool that can identify, quantify, and localize analytes without comprehensive a priori knowledge. It is well-suited for globally profiling neuropeptides and aiding in the discovery of novel peptides. Due to the low abundance and high chemical diversity of this class of peptides, several sample preparation methods, MS acquisition parameters, and data analysis strategies have been adapted from proteomics techniques to allow optimal neuropeptide characterization. Here, methods are described for isolating neuropeptides from complex biological tissues for sequence characterization, quantitation, and localization using liquid chromatography (LC)-MS and matrix-assisted laser desorption/ionization (MALDI)-MS. A protocol for preparing a neuropeptide database from the blue crab, Callinectes sapidus, an organism without comprehensive genomic information, is included. These workflows can be adapted to study other classes of endogenous peptides in different species using a variety of instruments.

Multi-Faceted Mass Spectrometric Investigation of Neuropeptides in Callinectes sapidus

Mass spectrometric characterization of neuropeptides provides sequence, quantitation, and localization information. This optimized workflow is not only useful for neuropeptide studies, but also other endogenous peptides. The protocols provided here describe sample preparation, MS acquisition, MS analysis, and database generation of neuropeptides using LC-ESI-MS, MALDI-MS spotting, and MALDI-MS imaging.

Neuropeptides are signaling molecules that regulate almost all physiological and behavioral processes, such as development, reproduction, food intake, and ...

Chemistry

Analysis of Lipid Signaling in Drosophila Photoreceptors using Mass Spectrometry

The activation of phospholipase C&#946; (PLC&#946;) is an essential step during sensory transduction in Drosophila photoreceptors. PLC&#946; activity results in the hydrolysis of the membrane lipid phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2] leading ultimately to the activation of transient receptor potential (TRP) and TRP like (TRPL) channels. The activity of PLC&#946; also leads subsequently to the generation of many lipid species several of which have been proposed to play a role in TRP and TRPL activation. In addition, several classes of lipids have been proposed to play key roles in organizing the cell biology of photoreceptors to optimize signaling reactions for optimal sensory transduction. Historically, these discoveries have been driven by the ability to isolate Drosophila mutants for enzymes that control the levels of specific lipids and perform analysis of photoreceptor physiology in these mutants. More recently, powerful mass spectrometry methods for isolation and quantitative analysis of lipids with high sensitivity and specificity have been developed. These are particularly suited for use in Drosophila where lipid analysis is now possible from photoreceptors without the need for radionuclide labeling. In this article, the conceptual and practical considerations in the use of lipid mass spectrometry for the robust, sensitive, and accurate quantitative assessment of various signaling lipids in Drosophila photoreceptors are covered. Along with existing methods in molecular genetics and physiological analysis such lipid is likely to enhance the power of photoreceptors as a model system for discoveries in biology.

Analysis of Lipid Signaling in Drosophila Photoreceptors using Mass Spectrometry

The manuscript presents versatile, robust, and sensitive mass spectrometry protocols to identify and quantify several classes of lipids from Drosophila photoreceptors.

The activation of phospholipase C&#946; (PLC&#946;) is an essential step during sensory transduction in Drosophila photoreceptors. PLC&#946; activity ...

Identification of Hemolytic and Phospholipase Activity in Crude Extracts from Sea Anemones by Straightforward Bioassays

Sea anemone venom composition includes polypeptide and non-proteins molecules. Cytolytic components have a high biotechnological and biomedical potential for designing new molecular tools. Sea anemone venom locates in glandular cells from ectoderm and sub-cellular structures called nematocysts, both of which are distributed throughout the sea anemone body. This characteristic implies challenges because the cells and nematocyst must be lysed to release the venom components with other non-toxic molecules. Therefore, first, the venom is derived from a crude extract (mixture of different and diverse molecules and tissue debris). The next step is to detect polypeptides with specific bioactivities. Here, we describe an efficient strategy to obtain the sea anemone crude extract and bioassay to identify the presence of cytolysins. The first step involves inexpensive and straightforward techniques (stirred and freeze-thaw cycle) to release cytolysins. We obtained the highest cytolytic activity and protein (~500 mg of protein from 20 g of dry weight). Next, the polypeptide complexity of the extract was analyzed by SDS-PAGE gel detecting proteins with molecular weights between 10 kDa and 250 kDa. In the hemolytic assay, we used sheep red blood cells and determined HU50 (11.1 &plusmn; 0.3 &#181;g/mL). In contrast, the presence of phospholipases in the crude extract was determined using egg yolk as a substrate in a solid medium with agarose. Overall, this study uses an efficient and inexpensive protocol to prepare the crude extract and applies replicable bioassays to identify cytolysins, molecules with biotechnological and biomedical interests.

Here, we describe a protocol to obtain crude venom extract from sea anemone and detect its hemolytic and phospholipase activity.

Sea anemone venom composition includes polypeptide and non-proteins molecules. Cytolytic components have a high biotechnological and biomedical potential ...

Lethality Bioassay Using Artemia salina L.

Natural products have been used since ancient times to produce medicines. Nowadays, there are plenty of chemotherapeutic drugs obtained from natural sources and used against a plethora of diseases. Unfortunately, most of these compounds often display systemic toxicity and adverse effects. In order to better evaluate the tolerability of selected potentially bioactive samples, brine shrimp (Artemia salina) is generally used as a model in lethality studies. The A. salina test is based on the ability of the studied bioactive compounds to kill the microcrustaceans in their larval stage (nauplii). This method represents a convenient starting point for cytotoxicity studies, as well as for the general toxicity screening of synthetic, semisynthetic, and natural products. It can be considered a simple, quick, and low-cost assay, compared to many other assays (in vitro cells or yeast strains, zebrafish, rodents) generally suitable for the aforementioned purposes; moreover, it can be easily performed even without any specific training. Overall, A. salina assay represents a useful tool for the preliminary toxicity evaluation of selected compounds and the bio-guided fractionation of natural product extracts.

Lethality Bioassay Using Artemia salina L.

This work aims to evaluate and review the Artemia salina lethality bioassay procedure, also identified as brine shrimp lethality assay. This simple and cheap method gives information about the general toxicity (considered as a preliminary toxicity evaluation) of samples, namely, natural products.

Natural products have been used since ancient times to produce medicines. Nowadays, there are plenty of chemotherapeutic drugs obtained from natural ...

Extraction and Quantification of Volatile Sex Pheromone Responses in C. elegans

Volatile Sex Pheromone Extraction and Chemoattraction Assay in Caenorhabditis elegans

Chemical communication is vital in organismal health, reproduction, and overall well-being. Understanding the molecular pathways, neural processes, and computations governing these signals remains an active area of research. The nematode Caenorhabditis elegans provides a powerful model for studying these processes as it produces a volatile sex pheromone. This pheromone is synthesized by virgin females or sperm-depleted hermaphrodites and serves as an attractant for males.
This protocol describes a detailed method for isolating the volatile sex pheromone from several C. elegans strains (WT strain N2, daf-22, and fog-2) and C. remanei. We also provide a protocol for quantifying the male chemotaxis response to the volatile sex pheromone. Our analysis utilizes measurements such as chemotaxis index (C.I.), arrival time (A.T.), and a trajectory plot to compare male responses under various conditions accurately. This method allows for robust comparisons between males of different genetic backgrounds or developmental stages. Furthermore, the experimental setup outlined here is adaptable to investigating other chemoattraction chemicals.

Author Spotlight: Examining Volatile Sex Pheromone Influence on Male C. elegans Behavior

This protocol establishes methods for extracting and quantifying responses to the volatile sex pheromone in C. elegans, providing tools to study chemical communication and navigation trajectory.

Chemical communication is vital in organismal health, reproduction, and overall well-being. Understanding the molecular pathways, neural processes, and ...

Behavior

Electroantennographic Bioassay as a Screening Tool for Host Plant Volatiles

Plant volatiles play an important role in plant-insect interactions. Herbivorous insects use plant volatiles, known as kairomones, to locate their host plant.1,2 When a host plant is an important agronomic commodity feeding damage by insect pests can inflict serious economic losses to growers. Accordingly, kairomones can be used as attractants to lure or confuse these insects and, thus, offer an environmentally friendly alternative to pesticides for insect control.3 Unfortunately, plants can emit a vast number volatiles with varying compositions and ratios of emissions dependent upon the phenology of the commodity or the time of day. This makes identification of biologically active components or blends of volatile components an arduous process. To help identify the bioactive components of host plant volatile emissions we employ the laboratory-based screening bioassay electroantennography (EAG). EAG is an effective tool to evaluate and record electrophysiologically the olfactory responses of an insect via their antennal receptors. The EAG screening process can help reduce the number of volatiles tested to identify promising bioactive components. However, EAG bioassays only provide information about activation of receptors. It does not provide information about the type of insect behavior the compound elicits; which could be as an attractant, repellent or other type of behavioral response. Volatiles eliciting a significant response by EAG, relative to an appropriate positive control, are typically taken on to further testing of behavioral responses of the insect pest. The experimental design presented will detail the methodology employed to screen almond-based host plant volatiles4,5 by measurement of the electrophysiological antennal responses of an adult insect pest navel orangeworm (Amyelois transitella) to single components and simple blends of components via EAG bioassay. The method utilizes two excised antennae placed across a "fork" electrode holder. The protocol demonstrated here presents a rapid, high-throughput standardized method for screening volatiles. Each volatile is at a set, constant amount as to standardize the stimulus level and thus allow antennal responses to be indicative of the relative chemoreceptivity. The negative control helps eliminate the electrophysiological response to both residual solvent and mechanical force of the puff. The positive control (in this instance acetophenone) is a single compound that has elicited a consistent response from male and female navel orangeworm (NOW) moth. An additional semiochemical standard that provides consistent response and is used for bioassay studies with the male NOW moth is (Z,Z)-11,13-hexdecadienal, an aldehyde component from the female-produced sex pheromone.6-8

A method to rapidly screen host plant volatiles by measurement of the electrophysiological response of adult navel orangeworm (Amyelois transitella) antennae to single components and blends via electroantennographic analysis is demonstrated.

Plant volatiles play an important role in plant-insect interactions. Herbivorous insects use plant volatiles, known as kairomones, to locate their host ...

Biology

A New Clarification Method to Visualize Biliary Degeneration During Liver Metamorphosis in Sea Lamprey (Petromyzon marinus)

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian countries, with a reported frequency of 1 in 5,000 in Taiwan. Although much is known about the management of biliary atresia, its pathogenesis is still elusive. The sea lamprey (Petromyzon marinus) provides a unique opportunity to examine the mechanism and progression of biliary degeneration. Sea lamprey develop through three distinct life stages: larval, parasitic, and adult. During the transition from larvae to parasitic juvenile, sea lamprey undergo metamorphosis with dramatic reorganization and remodeling in external morphology and internal organs. In the liver, the entire biliary system is lost, including the gall bladder and the biliary tree. A newly-developed method called &#8220;CLARITY&#8221; was modified to clarify the entire liver and the junction with the intestine in metamorphic sea lamprey. The process of biliary degeneration was visualized and discerned during sea lamprey metamorphosis by using laser scanning confocal microscopy. This method provides a powerful tool to study biliary atresia in a unique animal model.

A New Clarification Method to Visualize Biliary Degeneration During Liver Metamorphosis in Sea Lamprey Petromyzon marinus

Sea lamprey lose the gall bladder and bile ducts during metamorphosis, a process similar to human biliary atresia. A new fixation and clarification method (CLARITY) was modified to visualize the entire biliary tree using laser scanning confocal microscopy. This method provides a powerful tool to study biliary degeneration.

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian ...

The Identification of Sea Lamprey Pheromones Using Bioassay-Guided Fractionation

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A Fish-feeding Laboratory Bioassay to Assess the Antipredatory Activity of Secondary Metabolites from the Tissues of Marine Organisms

An Ultra-clean Multilayer Apparatus for Collecting Size Fractionated Marine Plankton and Suspended Particles

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles

Multi-Faceted Mass Spectrometric Investigation of Neuropeptides in Callinectes sapidus

Analysis of Lipid Signaling in Drosophila Photoreceptors using Mass Spectrometry

Identification of Hemolytic and Phospholipase Activity in Crude Extracts from Sea Anemones by Straightforward Bioassays

Lethality Bioassay Using Artemia salina L.

Volatile Sex Pheromone Extraction and Chemoattraction Assay in Caenorhabditis elegans

Electroantennographic Bioassay as a Screening Tool for Host Plant Volatiles

A New Clarification Method to Visualize Biliary Degeneration During Liver Metamorphosis in Sea Lamprey (Petromyzon marinus)