We thank the W.M. Keck Bioimaging Laboratory for use of their video microscopy work station. This study was supported by NSF grant IBN-0615435.

<ol>
	<li>Ward, G. E., Brokaw, C. J., Garbers, D. L., Vacquier, V. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemotaxis+of+Arbacia+punctulata+spermatozoa+to+resact,+a+peptide+from+the+egg+jelly+layer.">Chemotaxis of Arbacia punctulata spermatozoa to resact, a peptide from the egg jelly layer.</a> J. Cell Biol. 101, 2324-2329 (1985).</li><li>Olivera, R. G., Tomasi, L., Rovasio, R. A., Giojalas, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+velocity+and+induction+of+chemotactic+response+in+mouse+spermatozoa+by+follicular+and+oviductal+fluids.">Increased velocity and induction of chemotactic response in mouse spermatozoa by follicular and oviductal fluids.</a> J. Reprod. Fertil. 115, 23-27 (1999).</li><li>Fabro, G., Rovasio, R. A., Civalero, S., Frenkel, A., Caplan, S. R., Eisenbach, M., Giojalas, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemotaxis+of+capacitated+rabbit+spermatozoa+to+follicular+fluid+revealed+by+a+novel+directionality-based+assay.">Chemotaxis of capacitated rabbit spermatozoa to follicular fluid revealed by a novel directionality-based assay.</a> Biol. Reprod. 67, 1565-1571 (2002).</li><li>Sugiyama, H., Burnett, L., Xiang, X., Olson, J., Willis, S., Miao, A., Akema, T., Bieber, A. L., Chandler, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+multimer+formation+of+allurin,+a+sperm+chemoattractant+from+Xenopus+laevis+egg+jelly.">Purification and multimer formation of allurin, a sperm chemoattractant from Xenopus laevis egg jelly.</a> Mol. Reprod. 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R., Eisenbach, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+chemotaxis+when+the+fraction+of+responsive+cells+is+small--application+to+mammalian+sperm+guidance.">Analysis of chemotaxis when the fraction of responsive cells is small--application to mammalian sperm guidance.</a> Int. J. Dev. Biol. 52, 481-487 (2008).</li><li>B&#246;hmer, M., Van, Q., Weyand, I., Hagen, V., Beyermann, M., Matsumoto, M., Hoshi, M., Hildebrand, E., Kaupp, U. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ca2++spikes+in+the+flagellum+control+chemotactic+behavior+of+sperm.">Ca2+ spikes in the flagellum control chemotactic behavior of sperm.</a> EMBO J. 24, 2741-2752 (2005).</li><li>Shiba, K., Baba, S. A., Inoue, T., Yoshida, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ca2++bursts+occur+around+a+local+minimal+concentration+of+attractant+and+trigger+sperm+chemotactic+response.">Ca2+ bursts occur around a local minimal concentration of attractant and trigger sperm chemotactic response.</a> Proc. Natl. Acad. Sci. U.S.A. 105, 19312-19317 (2008).</li><li>Burnett, L. A., Sugiyama, H., Bieber, A. L., Chandler, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Egg+jelly+proteins+stimulate+directed+motility+in+Xenopus+laevis+sperm.">Egg jelly proteins stimulate directed motility in Xenopus laevis sperm.</a> Mol. Reprod. Dev. 78, 450-462 (2011).</li><li>Abaigar, T., Barbero, J., Holt, W. 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Chem. 286, 17311-17325 (2011).</li><li>Tholl, N., Naqvi, S., McLaughlin, E., Boyles, S., Bieber, A. L., Chandler, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Swimming+of+Xenopus+laevis+sperm+exhibits+multiple+gears+and+its+duration+is+extended+by+egg+jelly+constituents.">Swimming of Xenopus laevis sperm exhibits multiple gears and its duration is extended by egg jelly constituents.</a> Biol. Bull. 220, 174-185 (2011).</li><li>Eisenbach, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sperm+chemotaxis.">Sperm chemotaxis.</a> Rev. Reprod. 4, 56-66 (1999).</li><li>Riffell, J. A., Zimmer, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sex+and+flow:+the+consequences+of+fluid+shear+for+sperm-egg+interactions.">Sex and flow: the consequences of fluid shear for sperm-egg interactions.</a> J. Exp. Biol. 210, 3644-3660 (2007).</li><li>Corkidi, G., Taboada, B., Wood, C. D., Guerrero, A., Darszon, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracking+sperm+in+three-dimensions.">Tracking sperm in three-dimensions.</a> Biochem. Biophys. Res. Commun. 373, 125-129 (2008).</li><li>Himes, J. E., Riffell, J. A., Zimmer, C. A., Zimmer, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sperm+chemotaxis+as+revealed+with+live+and+synthetic+eggs.">Sperm chemotaxis as revealed with live and synthetic eggs.</a> Biol Bull. 220, 1-5 (2011).</li><li>Sun, F., Giojolas, L. C., Rovasio, R. A., Tur-Kaspa, I., Sanchez, R., Eisenbach, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lack+of+species-specificity+in+mammalian+sperm+chemotaxis.">Lack of species-specificity in mammalian sperm chemotaxis.</a> Dev. Biol. 255, 423-427 (2003).</li><li>Guidobaldi, H. A., Teves, M. E., U&#241;ates, D. R., Anastas&#237;a, A., Giojalas, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progesterone+from+the+cumulus+cells+is+the+sperm+chemoattractant+secreted+by+the+rabbit+oocyte+cumulus+complex.">Progesterone from the cumulus cells is the sperm chemoattractant secreted by the rabbit oocyte cumulus complex.</a> PLoS One. 3, e3040-e3040 (2008).</li><li>Oren-Benaroya, R., Orvieto, R., Gakamsky, A., Pinchasov, M., Eisenbach, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+sperm+chemoattractant+secreted+from+human+cumulus+cells+is+progesterone.">The sperm chemoattractant secreted from human cumulus cells is progesterone.</a> Hum. Reprod. 23, 2339-2345 (2008).</li><li>Teves, M. E., Guidobaldi, H. A., U&#241;ates, D. R., Sanchez, R., Miska, W., Publicover, S. J., Morales Garcia, A. A., Giojalas, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanism+for+human+sperm+chemotaxis+mediated+by+progesterone.">Molecular mechanism for human sperm chemotaxis mediated by progesterone.</a> PLoS One. 4, 8211-82 (2009).</li><li>Blengini, C. S., Teves, M. E., Uñates, D. R., Guidobaldi, H. A., Gatica, L. V., Giojalas, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+sperm+pattern+of+movement+during+chemotactic+re-orientation+towards+a+progesterone+source.">Human sperm pattern of movement during chemotactic re-orientation towards a progesterone source.</a> Asian J. Androl. 13, 769-773 (2011).</li><li>Strünker, T., Goodwin, N., Brenker, C., Kashikar, N. D., Weyand, I., Seifert, R., Kaupp, U. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+CatSper+channel+mediates+progesterone-induced+Ca2++influx+in+human+sperm.">The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm.</a> Nature. 471, 382-386 (2011).</li><li>Lishko, P. V., Botchkina, I. L., Kirichok, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progesterone+activates+the+principal+Ca2++channel+of+human+sperm.">Progesterone activates the principal Ca2+ channel of human sperm.</a> Nature. 471, 387-391 (2011).</li><li>Boyden, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+chemotactic+effect+of+mixtures+of+antibody+and+antigen+on+polymorphonuclear+leucocytes.">The chemotactic effect of mixtures of antibody and antigen on polymorphonuclear leucocytes.</a> J. Exp. Med. 115, 453-465 (1962).</li><li>Zigmond, S. H., Lauffenburger, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assays+of+leukocyte+chemotaxis.">Assays of leukocyte chemotaxis.</a> Annu. Rev. Med. 37, 149-155 (1986).</li><li>Villanueva-Diaz, C., Vadillo-Ortega, F., Kably-Ambe, A., Diaz-Pérez, M. A., Krivitzky, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evidence+that+human+follicular+fluid+contains+a+chemoattractant+for+spermatozoa.">Evidence that human follicular fluid contains a chemoattractant for spermatozoa.</a> Fertil. Steril. 54, 1180-1182 (1990).</li><li>Villanueva-Diaz, C., Arizs-Martinez, J., Bermejo-Martinez, L., Vadillo-Ortega, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progesterone+induces+human+sperm+chemotaxis.">Progesterone induces human sperm chemotaxis.</a> Fertil. Steril. 64, 1183-1188 (1995).</li><li>Olson, J., Xiang, X., Ziegert, T., Kittleson, A., Rawls, A., Bieber, A., Chandler, D. E. A. l. l. u. r. i. n. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=a+21+kD+sperm+chemoattractant+from+Xenopus+egg+jelly,+is+homologous+to+mammalian+sperm-binding+proteins.">a 21 kD sperm chemoattractant from Xenopus egg jelly, is homologous to mammalian sperm-binding proteins.</a> Proc. Natl. Acad. Sci. U.S.A. 98, 11205-11210 (2001).</li></ol>

No conflicts of interest declared.

Chemotaxis of cells moving by either amoeboid movement or flagella-powered swimming is found in many biological contexts and study of this phenomenon requires the availability of practical and reliable assays. Some examples of the phenomenon, such as attraction of sperm to a sea urchin egg or gathering of slime mold cells to form a fruiting body, have immediate visual impact. Quantitation of this phenomenon has been undertaken in a variety of ways as described by Eisenbach18. These assays include use of chemoa...

<table border="1">
 <tbody>
 <tr>
 <td>Name of Item</td>
 <td>Company</td>
 <td>Catalogue Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>24-well plates</td>
 <td>Becton-Dickenson</td>
 <td>35/1147</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>12 mm outer diameter inserts with 12 &mu;m pore membrane</td>
 <td>Millipore</td>
 <td>PIXP01250</td>
 <td>We previously used Costar-Corning transwell plate #3403 -now discontinued</td>
 </tr>
 <tr>
 <td>Zigmond chamber</td>
 <td>Neuroprobe</td>
 <td>Z02</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Silicone oil</td>
 <td>General Electric</td>
 <td>SF1154</td>
 <td>Equivalent to Dow Corning 550 Fluid</td>
 </tr>
 <tr>
 <td>Image J software</td>
 <td>Wayne Rasband, Research Services Branch, National Institute of Mental Health</td>
 <td>Free download at 
 http://rsbweb.nih.gov/ij</td>
 <td>Java program that runs on Windows, Linux and Mac</td>
 </tr>
 <tr>
 <td>MtrackJ software</td>
 <td>Erik Meijering/ 
 Imagescience/ 
 <a href="http://www.bigr.nl/">Biomedical Imaging Group</a>, Erasmus MC - University Medical Center Rotterdam</td>
 <td>Free download at <a href="http://www.imagescience.org/meijering/software/mtrackj/">http://www.imagescience.org/meijering/software/mtrackj/</a></td>
 <td>Java program that runs on Windows, Linux and Mac</td>
 </tr>
 <tr>
 <td>Virtual Dub software</td>
 <td><a href="http://www.virtualdub.org/gpl.html">GNU General Public Licensed</a> software</td>
 <td>Free download via <a href="http://www.virtualdub.org/index.html">http://www.virtualdub.org/index.html</a></td>
 <td>Setup instructions at the Image J website under plugins; for Windows only</td>
 </tr>
 <tr>
 <td>cellSens software</td>
 <td>Olympus</td>
 <td>See website: <a href="http://www.olympusamerica.com/seg_section/product.asp?product=1070">http://www.olympusamerica.com/seg_section/product.asp?product=1070</a></td>
 <td>Controls and acquires images from a variety of cameras. Also has image processing capability</td>
 </tr>
 </tbody>
</table>

two types of assays for detecting frog sperm chemoattraction

Sperm chemoattraction in invertebrates can be sufficiently robust that one can place a pipette containing the attractive peptide into a sperm suspension and microscopically visualize sperm accumulation around the pipette1. Sperm chemoattraction in vertebrates such as frogs, rodents and humans is more difficult to detect and requires quantitative assays. Such assays are of two major types - assays that quantitate sperm movement to a source of chemoattractant, so-called sperm accumulation assays, and assays that actually track the swimming trajectories of individual sperm.
Sperm accumulation assays are relatively rapid allowing tens or hundreds of assays to be done in a single day, thereby allowing dose response curves and time courses to be carried out relatively rapidly. These types of assays have been used extensively to characterize many well established chemoattraction systems - for example, neutrophil chemotaxis to bacterial peptides and sperm chemotaxis to follicular fluid. Sperm tracking assays can be more labor intensive but offer additional data on how chemoattractancts actually alter the swimming paths that sperm take. This type of assay is needed to demonstrate the orientation of sperm movement relative to the chemoattrractant gradient axis and to visualize characteristic turns or changes in orientation that bring the sperm closer to the egg.
Here we describe methods used for each of these two types of assays. The sperm accumulation assay utilized is called a "two-chamber" assay. Amphibian sperm are placed in a tissue culture plate insert with a polycarbonate filter floor having 12 &mu;m diameter pores. Inserts with sperm are placed into tissue culture plate wells containing buffer and a chemoatttractant carefully pipetted into the bottom well where the floor meets the wall (see Fig. 1). After incubation, the top insert containing the sperm reservoir is carefully removed, and sperm in the bottom chamber that have passed through the membrane are removed, pelleted and then counted by hemocytometer or flow cytometer.
The sperm tracking assay utilizes a Zigmond chamber originally developed for observing neutrophil chemotaxis and modified for observation of sperm by Giojalas and coworkers2,3. The chamber consists of a thick glass slide into which two vertical troughs have been machined. These are separated by a 1 mm wide observation platform. After application of a cover glass, sperm are loaded into one trough, the chemoattractant agent into the other and movement of individual sperm visualized by video microscopy. Video footage is then analyzed using software to identify two-dimensional cell movements in the x-y plane as a function of time (xyt data sets) that form the trajectory of each sperm.

Watch this Scientific Journal Video about Two Types of Assays for Detecting Frog Sperm Chemoattraction at JoVE.com

Two Types of Assays for Detecting Frog Sperm Chemoattraction

Eggs and the extracellular coatings around eggs frequently release peptides, proteins and small molecules that communicate with sperm to guide them to the egg thereby promoting fertilization. Using frog sperm we describe and compare two classes of assays used to detect sperm chemoattraction &#x2013; sperm accumulation assays and sperm tracking assays.

Sperm chemoattraction in invertebrates can be sufficiently robust that one can place a pipette containing the attractive peptide into a sperm suspension ...

two-types-of-assays-for-detecting-frog-sperm-chemoattraction

Research

JoVE Journal

Biology

19.0K Views.  University of Illinois, Urbana-Champaign. Eggs and the extracellular coatings around eggs frequently release peptides, proteins and small molecules that communicate with sperm to guide them to the egg thereby promoting fertilization. Using frog sperm we describe and compare two classes of assays used to detect sperm chemoattraction – sperm accumulation assays and sperm tracking assays.

Video: Two Types of Assays for Detecting Frog Sperm Chemoattraction

Harvesting Sperm and Artificial Insemination of Mice

Rodents of the genus Peromyscus (deer mice) are the most prevalent native North American mammals. Peromyscus species are used in a wide range of research including toxicology, epidemiology, ecology, behavioral, and genetic studies. Here they provide a useful model for demonstrations of artificial insemination. 

Methods similar to those displayed here have previously been used in several deer mouse studies, yet no detailed protocol has been published. Here we demonstrate the basic method of artificial insemination. This method entails extracting the testes from the rodent, then isolating the sperm from the epididymis and vas deferens. The mature sperm, now in a milk mixture, are placed in the female&#x2019;s reproductive tract at the time of ovulation. Fertilization is counted as day 0 for timing of embryo development. Embryos can then be retrieved at the desired time-point and manipulated.

Artificial insemination can be used in a variety of rodent species where exact embryo timing is crucial or hard to obtain. This technique is vital for species or strains (including most Peromyscus) which may not mate immediately and/or where mating is hard to assess. In addition, artificial insemination provides exact timing for embryo development either in mapping developmental progress and/or transgenic work. Reduced numbers of animals can be used since fertilization is guaranteed. This method has been vital to furthering the Peromyscus system, and will hopefully benefit others as well.

This protocol demonstrates methods for extracting sperm from the testes of males and then inseminating female mice. This procedure is useful when precise time is needed in developmental studies as well as transgenic work.

Rodents of the genus Peromyscus (deer mice) are the most prevalent native North American mammals.  Peromyscus species are used in a wide range of research ...

Neurocircuit Assays for Seizures in Epilepsy Mutants of Drosophila

Drosophila melanogaster is a useful tool for studying seizure like activity. A variety of mutants in which seizures can be induced through either physical shock or electrical stimulation is available for study of various aspects of seizure activity and behavior. All flies, including wild-type, will undergo seizure-like activity if stimulated at a high enough voltage. Seizure like activity is an all-or-nothing response and each genotype has a specific seizure threshold. The seizure threshold of a specific genotype of fly can be altered either by treatment with a drug or by genetic suppression or enhancement. The threshold is easily measured by electrophysiology. Seizure-like activity can be induced via high frequency electrical stimulation delivered directly to the brain and recorded through the dorsal longitudinal muscles (DLMs) in the thorax. The DLMs are innervated by part of the giant fiber system. Starting with low voltage, high frequency stimulation, and subsequently raising the voltage in small increments, the seizure threshold for a single fly can be measured.

Neurocircuit Assays for Seizures in Epilepsy Mutants of Drosophila

Using high frequency electrical stimulation, seizure-like activity can be induced in Drosophila. This activity is easily recorded from the giant fiber system.

Drosophila melanogaster is a useful tool for studying seizure like activity. A variety of mutants in which seizures can be induced through either physical ...

Techniques for Imaging Ca2+ Signaling in Human Sperm

Fluorescence microscopy of cells loaded with fluorescent, Ca2+-sensitive dyes is used for measurement of spatial and temporal aspects of Ca2+ signaling in live cells. Here we describe the method used in our laboratories for loading suspensions of human sperm with Ca2+-reporting dyes and measuring the fluorescence signal during physiological stimulation. Motile cells are isolated by direct swim-up and incubated under capacitating conditions for 0-24 h, depending upon the experiment. The cell-permeant AM (acetoxy methyl ester) ester form of the Ca2+-reporting dye is then added to a cell aliquot and a period of 1 h is allowed for loading of the dye into the cytoplasm. We use visible wavelength dyes to minimize photo-damage to the cells, but this means that ratiometric recording is not possible. Advantages and disadvantages of this approach are discussed. During the loading period cells are introduced into an imaging chamber and allowed to adhere to a poly-D-lysine coated coverslip. At the end of the loading period excess dye and loose cells are removed by connection of the chamber to the perfusion apparatus. The chamber is perfused continuously, stimuli and modified salines are then added to the perfusion header. Experiments are recorded by time-lapse acquisition of fluorescence images and analyzed in detail offline, by manually drawing regions of interest. Data are normalized to pre-stimulus levels such that, for each cell (or part of a cell), a graph showing the Ca2+ response as % change in fluorescence is obtained.

Techniques for Imaging Ca2+ Signaling in Human Sperm

Stimulus-evoked [Ca2+]i signals of individual human sperm are assessed. Motile cells are loaded with Ca2+-sensitive fluorescent dye (AM-ester method) and immobilised in a perfusable chamber. Cells are imaged by time-lapse fluorescence microscopy and stimulated via the perfusing medium. Responses of single cells (or regions) are analysed offline using Excel.

Fluorescence microscopy of cells loaded with fluorescent, Ca2+-sensitive dyes is used for measurement of spatial and temporal aspects of Ca2+ signaling in ...

Analysis of Schwann-astrocyte Interactions Using In Vitro Assays

Schwann cells are one of the commonly used cells in repair strategies following spinal cord injuries. Schwann cells are capable of supporting axonal regeneration and sprouting by secreting growth factors 1,2 and providing growth promoting adhesion molecules 3 and extracellular matrix molecules 4. In addition they myelinate the demyelinated axons at the site of injury 5.
However following transplantation, Schwann cells do not migrate from the site of implant and do not intermingle with the host astrocytes 6,7. This results in formation of a sharp boundary between the Schwann cells and astrocytes, creating an obstacle for growing axons trying to exit the graft back into the host tissue proximally and distally. Astrocytes in contact with Schwann cells also undergo hypertrophy and up-regulate the inhibitory molecules 8-13.
In vitro assays have been used to model Schwann cell-astrocyte interactions and have been important in understanding the mechanism underlying the cellular behaviour.
These in vitro assays include boundary assay, where a co-culture is made using two different cells with each cell type occupying different territories with only a small gap separating the two cell fronts. As the cells divide and migrate, the two cellular fronts get closer to each other and finally collide. This allows the behaviour of the two cellular populations to be analyzed at the boundary. Another variation of the same technique is to mix the two cellular populations in culture and over time the two cell types segregate with Schwann cells clumped together as islands in between astrocytes together creating multiple Schwann-astrocyte boundaries.
The second assay used in studying the interaction of two cell types is the migration assay where cellular movement can be tracked on the surface of the other cell type monolayer 14,15. This assay is commonly known as inverted coverslip assay. Schwann cells are cultured on small glass fragments and they are inverted face down onto the surface of astrocyte monolayers and migration is assessed from the edge of coverslip.
Both assays have been instrumental in studying the underlying mechanisms involved in the cellular exclusion and boundary formation. Some of the molecules identified using these techniques include N-Cadherins 15, Chondroitin Sulphate proteoglycans(CSPGs) 16,17, FGF/Heparin 18, Eph/Ephrins19.
This article intends to describe boundary assay and migration assay in stepwise fashion and elucidate the possible technical problems that might occur.

Analysis of Schwann-astrocyte Interactions Using In Vitro Assays

This article intends to describe in stepwise fashion the commonly used in vitro assays used in studying Schwann cell-asrtocyte interactions.

Schwann cells are one of the commonly used cells in repair strategies following spinal cord injuries. Schwann cells are capable of supporting axonal ...

Extraction of Tissue Antigens for Functional Assays

Many of the antigen targets of adaptive immune response, recognized by B and T cells, have not been defined 1. This is particularly true in autoimmune diseases and cancer2. Our aim is to investigate the antigens recognized by human T cells in the autoimmune disease type 1 diabetes 1,3,4,5. To analyze human T-cell responses against tissue where the antigens recognized by T cells are not identified we developed a method to extract protein antigens from human tissue in a format that is compatible with functional assays 6. Previously, T-cell responses to unpurified tissue extracts could not be measured because the extraction methods yield a lysate that contained detergents that were toxic to human peripheral blood mononuclear cells. Here we describe a protocol for extracting proteins from human tissues in a format that is not toxic to human T cells. The tissue is homogenized in a mixture of butan-1-ol, acetonitrile and water (BAW). The protein concentration in the tissue extract is measured and a known mass of protein is aliquoted into tubes. After extraction, the organic solvents are removed by lyophilization. Lyophilized tissue extracts can be stored until required. For use in assays of immune function, a suspension of immune cells, in appropriate culture media, can be added directly to the lyophilized extract. Cytokine production and proliferation by PBMC, in response to extracts prepared using this method, were readily measured. Hence, our method allows the rapid preparation of human tissue lysates that can be used as a source of antigens in the analysis of T-cell responses. We suggest that this method will facilitate the analysis of adaptive immune responses to tissues in transplantation, cancer and autoimmunity.

A simple protocol for preparing extracts of human tissue to be used as a source of antigens in functional T-cell assays is described. This method allows T-cell responses to tissue-derived antigens to be measured in vitro.

Many of the antigen targets of adaptive immune response, recognized by B and T cells, have not been defined 1. This is particularly true in autoimmune ...

Assessing Differences in Sperm Competitive Ability in Drosophila

Competition among conspecific males for fertilizing the ova is one of the mechanisms of sexual selection, i.e. selection that operates on maximizing the number of successful mating events rather than on maximizing survival and viability 1. Sperm competition represents the competition between males after copulating with the same female 2, in which their sperm are coincidental in time and space. This phenomenon has been reported in multiple species of plants and animals 3. For example, wild-caught D. melanogaster females usually contain sperm from 2-3 males 4. The sperm are stored in specialized organs with limited storage capacity, which might lead to the direct competition of the sperm from different males 2,5.
Comparing sperm competitive ability of different males of interest (experimental male types) has been performed through controlled double-mating experiments in the laboratory 6,7. Briefly, a single female is exposed to two different males consecutively, one experimental male and one cross-mating reference male. The same mating scheme is then followed using other experimental male types thus facilitating the indirect comparison of the competitive ability of their sperm through a common reference. The fraction of individuals fathered by the experimental and reference males is identified using markers, which allows one to estimate sperm competitive ability using simple mathematical expressions 7,8. In addition, sperm competitive ability can be estimated in two different scenarios depending on whether the experimental male is second or first to mate (offense and defense assay, respectively) 9, which is assumed to be reflective of different competence attributes.
Here, we describe an approach that helps to interrogate the role of different genetic factors that putatively underlie the phenomenon of sperm competitive ability in D. melanogaster.

Assessing Differences in Sperm Competitive Ability in Drosophila

Differential sperm competitive ability among Drosophila males with distinct genotypes can be ascertained through double-mating experiments. Each of these experiments involves one of the males of interest and a reference male. Readily identifiable markers in the progeny allow inference of the fraction of individuals fathered by each male.

Competition among conspecific males for fertilizing the ova is one of the mechanisms of sexual selection, i.e. selection that operates on maximizing the ...

Viability Assays for Cells in Culture

Manual cell counts on a microscope are a sensitive means of assessing cellular viability but are time-consuming and therefore expensive. Computerized viability assays are expensive in terms of equipment but can be faster and more objective than manual cell counts. The present report describes the use of three such viability assays. Two of these assays are infrared and one is luminescent. Both infrared assays rely on a 16&#160;bit Odyssey Imager. One infrared assay uses the DRAQ5 stain for nuclei combined with the Sapphire stain for cytosol and is visualized in the 700 nm channel. The other infrared assay, an In-Cell Western, uses antibodies against cytoskeletal proteins (&#945;-tubulin or microtubule associated protein 2) and labels them in the 800 nm channel. The third viability assay is a commonly used luminescent assay for ATP, but we use a quarter of the recommended volume to save on cost. These measurements are all linear and correlate with the number of cells plated, but vary in sensitivity. All three assays circumvent time-consuming microscopy and sample the entire well, thereby reducing sampling error. Finally, all of the assays can easily be completed within one day of the end of the experiment, allowing greater numbers of experiments to be performed within short timeframes. However, they all rely on the assumption that cell numbers remain in proportion to signal strength after treatments, an assumption that is sometimes not met, especially for cellular ATP. Furthermore, if cells increase or decrease in size after treatment, this might affect signal strength without affecting cell number. We conclude that all viability assays, including manual counts, suffer from a number of caveats, but that computerized viability assays are well worth the initial investment. Using all three assays together yields a comprehensive view of cellular structure and function.

Therapeutic compounds are often first examined in vitro with viability assays. Blind cell counts by a human observer can be highly sensitive to small changes in cell number but do not assess function. Computerized viability assays, as described here, can assess both structure and function in an objective manner.

Manual cell counts on a microscope are a sensitive means of assessing cellular viability but are time-consuming and therefore expensive. Computerized ...

Development of an Insert Co-culture System of Two Cellular Types in the Absence of Cell-Cell Contact

The role of secreted soluble factors in the modification of cellular responses is a recurrent theme in the study of all tissues and systems. In an attempt to make straightforward the very complex relationships between the several cellular subtypes that compose multicellular organisms, in vitro techniques have been developed to help researchers acquire a detailed understanding of single cell populations. One of these techniques uses inserts with a permeable membrane allowing secreted soluble factors to diffuse. Thus, a population of cells grown in inserts can be co-cultured in a well or dish containing a different cell type for evaluating cellular changes following paracrine signaling in the absence of cell-cell contact. Such insert co-culture systems offer various advantages over other co-culture techniques, namely bidirectional signaling, conserved cell polarity and population-specific detection of cellular changes. In addition to being utilized in the field of inflammation, cancer, angiogenesis and differentiation, these co-culture systems are of prime importance in the study of the intricate relationships that exist between the different cellular subtypes present in the central nervous system, particularly in the context of neuroinflammation. This article offers general methodological guidelines in order to set up an experiment in order to evaluating cellular changes mediated by secreted soluble factors using an insert co-culture system. Moreover, a specific protocol to measure the neuroinflammatory effects of cytokines secreted by lipopolysaccharide-activated N9 microglia on neuronal PC12 cells will be detailed, offering a concrete understanding of insert co-culture methodology.

In multicellular organisms, secreted soluble factors elicit responses from different cell types as a result of paracrine signaling. Insert co-culture systems offer a simple way to assess the changes mediated by secreted soluble factors in the absence of cell-cell contact.

The role of secreted soluble factors in the modification of cellular responses is a recurrent theme in the study of all tissues and systems. In an attempt ...

Fish Sperm Assessment Using Software and Cooling Devices

For gamete quality evaluation, there are innovative, rapid, and quantitative techniques that can provide useful data for aquaculture. Computerized systems for sperm analysis were developed to measure several parameters and one of the most commonly measured is the sperm motility.
Initially, this computer technology was designed for mammalian species, although it can also be used for fish sperm analysis. Fish have specific features that can affect sperm assessment such as a short motility time after activation and, in some cases, adaptation to lower temperatures. Thus, it is necessary to modify both software and hardware components to make motility analysis more efficient for fish sperm analysis. For mammalian sperm, the heating plate is used to maintain optimal temperatures of spermatozoa. However, for some fish species, it is advantageous to use a lower temperature to prolong the duration of motility, since the sperm remain active for less than 2 min. Therefore, cooling devices are necessary to refrigerate samples at constant temperature over the time of analysis, including on the optical microscope. This protocol describes the analysis of fish sperm motility using software for sperm analysis and new cooling devices to optimize the results.

The present protocol describes a procedure of fish sperm assessment using computer-assisted sperm analysis and cooling devices. The software gives a rapid, accurate and quantitative analysis of fish sperm quality based on spermatozoa motility, which can be a useful tool in aquaculture to improve reproduction success.

For gamete quality evaluation, there are innovative, rapid, and quantitative techniques that can provide useful data for aquaculture. Computerized systems ...

Sperm Collection of Differential Quality Using Density Gradient Centrifugation

In sexual reproduction, a male gamete or sperm cell fuses with a female gamete to bring about fertilization. However, a large number of sperm cells with fertilizing ability are required to interact with a female gamete to ensure fertilization. As such, the fertilizing ability of individual sperm cells is critical for successful reproduction. Density gradient centrifugation has been utilized for several decades as a reproducible, fast, efficient, effective and extremely adaptable method to collect only high-quality sperm to be used in assisted reproductive technology. The protocols we described herein focus on the utilization of the discontinuous Percoll density gradient centrifugation (PDGC) technique to isolate three distinct populations of rooster sperm by their quality. We were able to collect low-, medium- and high-quality sperm. We also describe reproducible protocols that entail determining fertility potential of sperm by assessing their viability, mobility and penetrability. Collection of sperm by their quality using PDGC technique would be useful to accurately and thoroughly characterize sperm with differential fertility potential.

In this paper, we aim to describe the performance of the density gradient centrifugation technique and its application in sperm physiology research.

In sexual reproduction, a male gamete or sperm cell fuses with a female gamete to bring about fertilization. However, a large number of sperm cells with ...